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94
bsp_howto/ada95_interrupt.rst
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@ -1,81 +1,75 @@
.. comment SPDX-License-Identifier: CC-BY-SA-4.0
.. COMMENT: COPYRIGHT (c) 1988-2008.
.. COMMENT: On-Line Applications Research Corporation (OAR).
.. COMMENT: All rights reserved.
Ada95 Interrupt Support
#######################
Introduction
============
This chapter describes what is required to enable Ada interrupt
and error exception handling when using GNAT over RTEMS.
This chapter describes what is required to enable Ada interrupt and error
exception handling when using GNAT over RTEMS.
The GNAT Ada95 interrupt support RTEMS was developed by
Jiri Gaisler <jgais@ws.estec.esa.nl> who also wrote this
chapter.
The GNAT Ada95 interrupt support RTEMS was developed by Jiri Gaisler
<jgais@ws.estec.esa.nl> who also wrote this chapter.
Mapping Interrupts to POSIX Signals
===================================
In Ada95, interrupts can be attached with the interrupt_attach pragma.
For most systems, the gnat run-time will use POSIX signal to implement
the interrupt handling, mapping one signal per interrupt. For interrupts
to be propagated to the attached Ada handler, the corresponding signal
must be raised when the interrupt occurs.
In Ada95, interrupts can be attached with the interrupt_attach pragma. For
most systems, the gnat run-time will use POSIX signal to implement the
interrupt handling, mapping one signal per interrupt. For interrupts to be
propagated to the attached Ada handler, the corresponding signal must be raised
when the interrupt occurs.
The same mechanism is used to generate Ada error exceptions.
Three error exceptions are defined: program, constraint and storage
error. These are generated by raising the predefined signals: SIGILL,
SIGFPE and SIGSEGV. These signals should be raised when a spurious
or erroneous trap occurs.
The same mechanism is used to generate Ada error exceptions. Three error
exceptions are defined: program, constraint and storage error. These are
generated by raising the predefined signals: SIGILL, SIGFPE and SIGSEGV. These
signals should be raised when a spurious or erroneous trap occurs.
To enable gnat interrupt and error exception support for a particular
BSP, the following has to be done:
To enable gnat interrupt and error exception support for a particular BSP, the
following has to be done:
# Write an interrupt/trap handler that will raise the corresponding
signal depending on the interrupt/trap number.
- Write an interrupt/trap handler that will raise the corresponding signal
depending on the interrupt/trap number.
# Install the interrupt handler for all interrupts/traps that will be
handled by gnat (including spurious).
- Install the interrupt handler for all interrupts/traps that will be handled
by gnat (including spurious).
# At startup, gnat calls ``__gnat_install_handler()``. The BSP
must provide this function which installs the interrupt/trap handlers.
- At startup, gnat calls ``__gnat_install_handler()``. The BSP must provide
this function which installs the interrupt/trap handlers.
Which CPU-interrupt will generate which signal is implementation
defined. There are 32 POSIX signals (1 - 32), and all except the
three error signals (SIGILL, SIGFPE and SIGSEGV) can be used. I
would suggest to use the upper 16 (17 - 32) which do not
have an assigned POSIX name.
Which CPU-interrupt will generate which signal is implementation defined. There
are 32 POSIX signals (1 - 32), and all except the three error signals (SIGILL,
SIGFPE and SIGSEGV) can be used. I would suggest to use the upper 16 (17 - 32)
which do not have an assigned POSIX name.
Note that the pragma interrupt_attach will only bind a signal
to a particular Ada handler - it will not unmask the
interrupt or do any other things to enable it. This have to be
done separately, typically by writing various device register.
Note that the pragma interrupt_attach will only bind a signal to a particular
Ada handler - it will not unmask the interrupt or do any other things to enable
it. This have to be done separately, typically by writing various device
register.
Example Ada95 Interrupt Program
===============================
An example program (``irq_test``) is included in the
Ada examples package to show how interrupts can be handled
in Ada95. Note that generation of the test interrupt
(``irqforce.c``) is BSP specific and must be edited.
An example program (``irq_test``) is included in the Ada examples package to
show how interrupts can be handled in Ada95. Note that generation of the test
interrupt (``irqforce.c``) is BSP specific and must be edited.
NOTE: The ``irq_test`` example was written for the SPARC/ERC32
BSP.
.. note::
The ``irq_test`` example was written for the SPARC/ERC32 BSP.
Version Requirements
====================
With RTEMS 4.0, a patch was required to psignal.c in RTEMS
sources (to correct a bug associated to the default action of
signals 15-32). The SPARC/ERC32 RTEMS BSP includes the``gnatsupp`` subdirectory that can be used as an example
With RTEMS 4.0, a patch was required to psignal.c in RTEMS sources (to correct
a bug associated to the default action of signals 15-32). The SPARC/ERC32
RTEMS BSP includes the``gnatsupp`` subdirectory that can be used as an example
for other BSPs.
With GNAT 3.11p, a patch is required for ``a-init.c`` to invoke
the BSP specific routine that installs the exception handlers.
.. COMMENT: COPYRIGHT (c) 1988-2008.
.. COMMENT: On-Line Applications Research Corporation (OAR).
.. COMMENT: All rights reserved.
With GNAT 3.11p, a patch is required for ``a-init.c`` to invoke the BSP
specific routine that installs the exception handlers.

170
bsp_howto/analog.rst
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@ -1,12 +1,15 @@
.. comment SPDX-License-Identifier: CC-BY-SA-4.0
.. COMMENT: COPYRIGHT (c) 1988-2002.
.. COMMENT: On-Line Applications Research Corporation (OAR).
.. COMMENT: All rights reserved.
Analog Driver
#############
The Analog driver is responsible for providing an
interface to Digital to Analog Converters (DACs) and
Analog to Digital Converters (ADCs). The capabilities provided
by this class of device driver are:
The Analog driver is responsible for providing an interface to Digital to
Analog Converters (DACs) and Analog to Digital Converters (ADCs). The
capabilities provided by this class of device driver are:
- Initialize an Analog Board
@ -22,64 +25,61 @@ by this class of device driver are:
- Reinitialize DACS
Most analog devices are found on I/O cards that support multiple
DACs or ADCs on a single card.
Most analog devices are found on I/O cards that support multiple DACs or ADCs
on a single card.
There are currently no analog device drivers included in the
RTEMS source tree. The information provided in this chapter
is based on drivers developed for applications using RTEMS.
It is hoped that this driver model information can form the
basis for a standard analog driver model that can be supported
in future RTEMS distribution.
There are currently no analog device drivers included in the RTEMS source tree.
The information provided in this chapter is based on drivers developed for
applications using RTEMS. It is hoped that this driver model information can
form the basis for a standard analog driver model that can be supported in
future RTEMS distribution.
Major and Minor Numbers
=======================
The *major* number of a device driver is its index in the
RTEMS Device Address Table.
The ``major`` number of a device driver is its index in the RTEMS Device
Address Table.
A *minor* number is associated with each device instance
managed by a particular device driver. An RTEMS minor number
is an ``unsigned32`` entity. Convention calls for
dividing the bits in the minor number down into categories
A ``minor`` number is associated with each device instance managed by a
particular device driver. An RTEMS minor number is an ``unsigned32`` entity.
Convention calls for dividing the bits in the minor number down into categories
like the following:
- *board* - indicates the board a particular device is located on
- ``board`` - indicates the board a particular device is located on
- *port* - indicates the particular device on a board.
- ``port`` - indicates the particular device on a board.
From the above, it should be clear that a single device driver
can support multiple copies of the same board in a single system.
The minor number is used to distinguish the devices.
From the above, it should be clear that a single device driver can support
multiple copies of the same board in a single system. The minor number is used
to distinguish the devices.
Analog Driver Configuration
===========================
There is not a standard analog driver configuration table but some
fields are common across different drivers. The analog driver
configuration table is typically an array of structures with each
structure containing the information for a particular board.
The following is a list of the type of information normally required
to configure an analog board:
There is not a standard analog driver configuration table but some fields are
common across different drivers. The analog driver configuration table is
typically an array of structures with each structure containing the information
for a particular board. The following is a list of the type of information
normally required to configure an analog board:
*board_offset*
``board_offset``
is the base address of a board.
*DAC_initial_values*
is an array of the voltages that should be written to each DAC
during initialization. This allows the driver to start the board
in a known state.
``DAC_initial_values``
is an array of the voltages that should be written to each DAC during
initialization. This allows the driver to start the board in a known
state.
Initialize an Analog Board
==========================
At system initialization, the analog driver's initialization entry point
will be invoked. As part of initialization, the driver will perform
whatever board initialization is required and then set all
outputs to their configured initial state.
At system initialization, the analog driver's initialization entry point will
be invoked. As part of initialization, the driver will perform whatever board
initialization is required and then set all outputs to their configured initial
state.
The analog driver may register a device name for each DAC and ADC in
the system.
The analog driver may register a device name for each DAC and ADC in the
system.
Open a Particular Analog
========================
@ -88,8 +88,8 @@ This is the driver open call. Usually this call does nothing other than
validate the minor number.
With some drivers, it may be necessary to allocate memory when a particular
device is opened. If that is the case, then this is often the place
to do this operation.
device is opened. If that is the case, then this is often the place to do this
operation.
Close a Particular Analog
=========================
@ -97,77 +97,69 @@ Close a Particular Analog
This is the driver close call. Usually this call does nothing.
With some drivers, it may be necessary to allocate memory when a particular
device is opened. If that is the case, then this is the place
where that memory should be deallocated.
device is opened. If that is the case, then this is the place where that
memory should be deallocated.
Read from a Particular Analog
=============================
This corresponds to the driver read call. After validating the minor
number and arguments, this call reads the indicated device. Most analog
devices store the last value written to a DAC. Since DACs are output
only devices, saving the last written value gives the appearance that
DACs can be read from also. If the device is an ADC, then it is sampled.
This corresponds to the driver read call. After validating the minor number
and arguments, this call reads the indicated device. Most analog devices store
the last value written to a DAC. Since DACs are output only devices, saving
the last written value gives the appearance that DACs can be read from also.
If the device is an ADC, then it is sampled.
*NOTE:* Many boards have multiple analog inputs but only one ADC. On
these boards, it will be necessary to provide some type of mutual exclusion
during reads. On these boards, there is a MUX which must be switched
before sampling the ADC. After the MUX is switched, the driver must
delay some short period of time (usually microseconds) before the
signal is stable and can be sampled. To make matters worse, some ADCs
cannot respond to wide voltage swings in a single sample. On these
ADCs, one must do two samples when the voltage swing is too large.
On a practical basis, this means that the driver usually ends up
double sampling the ADC on these systems.
.. note::
The value returned is a single precision floating point number
representing the voltage read. This value is stored in the``argument_block`` passed in to the call. By returning the
voltage, the caller is freed from having to know the number of
bits in the analog and board dependent conversion algorithm.
Many boards have multiple analog inputs but only one ADC. On these boards,
it will be necessary to provide some type of mutual exclusion during reads.
On these boards, there is a MUX which must be switched before sampling the
ADC. After the MUX is switched, the driver must delay some short period of
time (usually microseconds) before the signal is stable and can be sampled.
To make matters worse, some ADCs cannot respond to wide voltage swings in a
single sample. On these ADCs, one must do two samples when the voltage
swing is too large. On a practical basis, this means that the driver
usually ends up double sampling the ADC on these systems.
The value returned is a single precision floating point number representing the
voltage read. This value is stored in the ``argument_block`` passed in to the
call. By returning the voltage, the caller is freed from having to know the
number of bits in the analog and board dependent conversion algorithm.
Write to a Particular Analog
============================
This corresponds to the driver write call. After validating the minor
number and arguments, this call writes the indicated device. If the
specified device is an ADC, then an error is usually returned.
This corresponds to the driver write call. After validating the minor number
and arguments, this call writes the indicated device. If the specified device
is an ADC, then an error is usually returned.
The value written is a single precision floating point number
representing the voltage to be written to the specified DAC.
This value is stored in the ``argument_block`` passed in to the
call. By passing the voltage to the device driver, the caller is
freed from having to know the number of bits in the analog
and board dependent conversion algorithm.
The value written is a single precision floating point number representing the
voltage to be written to the specified DAC. This value is stored in the
``argument_block`` passed in to the call. By passing the voltage to the device
driver, the caller is freed from having to know the number of bits in the
analog and board dependent conversion algorithm.
Reset DACs
==========
This is one of the IOCTL functions supported by the I/O control
device driver entry point. When this IOCTL function is invoked,
all of the DACs are written to 0.0 volts.
This is one of the IOCTL functions supported by the I/O control device driver
entry point. When this IOCTL function is invoked, all of the DACs are written
to 0.0 volts.
Reinitialize DACS
=================
This is one of the IOCTL functions supported by the I/O control
device driver entry point. When this IOCTL function is invoked,
all of the DACs are written with the initial value configured
for this device.
This is one of the IOCTL functions supported by the I/O control device driver
entry point. When this IOCTL function is invoked, all of the DACs are written
with the initial value configured for this device.
Get Last Written Values
=======================
This is one of the IOCTL functions supported by the I/O control
device driver entry point. When this IOCTL function is invoked,
the following information is returned to the caller:
This is one of the IOCTL functions supported by the I/O control device driver
entry point. When this IOCTL function is invoked, the following information is
returned to the caller:
- last value written to the specified DAC
- timestamp of when the last write was performed
.. COMMENT: COPYRIGHT (c) 1988-2002.
.. COMMENT: On-Line Applications Research Corporation (OAR).
.. COMMENT: All rights reserved.

165
bsp_howto/ata.rst
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@ -1,5 +1,9 @@
.. comment SPDX-License-Identifier: CC-BY-SA-4.0
.. COMMENT: COPYRIGHT (c) 1988-2002.
.. COMMENT: On-Line Applications Research Corporation (OAR).
.. COMMENT: All rights reserved.
ATA Driver
##########
@ -11,10 +15,10 @@ ATA device - physical device attached to an IDE controller
Introduction
============
ATA driver provides generic interface to an ATA device. ATA driver is
hardware independent implementation of ATA standard defined in working draft
"AT Attachment Interface with Extensions (ATA-2)" X3T10/0948D revision 4c,
March 18, 1996. ATA Driver based on IDE Controller Driver and may be used for
ATA driver provides generic interface to an ATA device. ATA driver is hardware
independent implementation of ATA standard defined in working draft "AT
Attachment Interface with Extensions (ATA-2)" X3T10/0948D revision 4c, March
18, 1996. ATA Driver based on IDE Controller Driver and may be used for
computer systems with single IDE controller and with multiple as well. Although
current implementation has several restrictions detailed below ATA driver
architecture allows easily extend the driver. Current restrictions are:
@ -24,34 +28,39 @@ architecture allows easily extend the driver. Current restrictions are:
- Only PIO mode is supported but both poll and interrupt driven
The reference implementation for ATA driver can be found in``cpukit/libblock/src/ata.c``.
The reference implementation for ATA driver can be found in
``cpukit/libblock/src/ata.c``.
Initialization
==============
The ``ata_initialize`` routine is responsible for ATA driver
initialization. The main goal of the initialization is to detect and
register in the system all ATA devices attached to IDE controllers
successfully initialized by the IDE Controller driver.
initialization. The main goal of the initialization is to detect and register
in the system all ATA devices attached to IDE controllers successfully
initialized by the IDE Controller driver.
In the implementation of the driver, the following actions are performed:
.. code:: c
.. code-block:: c
rtems_device_driver ata_initialize(
rtems_device_major_number major,
rtems_device_minor_number minor,
void \*arg
void *arg
)
{
initialize internal ATA driver data structure
for each IDE controller successfully initialized by the IDE Controller
driver
for each IDE controller successfully initialized by the IDE Controller driver
if the controller is interrupt driven
set up interrupt handler
obtain information about ATA devices attached to the controller
with help of EXECUTE DEVICE DIAGNOSTIC command
for each ATA device detected on the controller
obtain device parameters with help of DEVICE IDENTIFY command
register new ATA device as new block device in the system
}
@ -61,17 +70,19 @@ multitasking environment during the driver initialization.
Detected ATA devices are registered in the system as physical block devices
(see libblock library description). Device names are formed based on IDE
controller minor number device is attached to and device number on the
controller (0 - Master, 1 - Slave). In current implementation 64 minor
numbers are reserved for each ATA device which allows to support up to 63
logical partitions per device.
.. code:: c
controller (0 - Master, 1 - Slave). In current implementation 64 minor numbers
are reserved for each ATA device which allows to support up to 63 logical
partitions per device.
================ ============= =========== ================
controller minor device number device name ata device minor
================ ============= =========== ================
0 0 hda 0
0 1 hdb 64
1 0 hdc 128
1 1 hdd 172
... ... ...
... ... ... ...
================ ============= =========== ================
ATA Driver Architecture
=======================
@ -79,102 +90,92 @@ ATA Driver Architecture
ATA Driver Main Internal Data Structures
----------------------------------------
ATA driver works with ATA requests. ATA request is described by the
following structure:
.. code:: c
ATA driver works with ATA requests. ATA request is described by the following
structure:
/* ATA request \*/
.. code-block:: c
/* ATA request */
typedef struct ata_req_s {
Chain_Node link; /* link in requests chain \*/
char type; /* request type \*/
ata_registers_t regs; /* ATA command \*/
uint32_t cnt; /* Number of sectors to be exchanged \*/
uint32_t cbuf; /* number of current buffer from breq in use \*/
uint32_t pos; /* current position in 'cbuf' \*/
blkdev_request \*breq; /* blkdev_request which corresponds to the
* ata request
\*/
Chain_Node link; /* link in requests chain */
char type; /* request type */
ata_registers_t regs; /* ATA command */
uint32_t cnt; /* Number of sectors to be exchanged */
uint32_t cbuf; /* number of current buffer from breq in use */
uint32_t pos; /* current position in 'cbuf' */
blkdev_request *breq; /* blkdev_request which corresponds to the ata request */
rtems_id sema; /* semaphore which is used if synchronous
* processing of the ata request is required
\*/
rtems_status_code status; /* status of ata request processing \*/
int error; /* error code \*/
* processing of the ata request is required */
rtems_status_code status; /* status of ata request processing */
int error; /* error code */
} ata_req_t;
ATA driver supports separate ATA requests queues for each IDE
controller (one queue per controller). The following structure contains
information about controller's queue and devices attached to the controller:
.. code:: c
ATA driver supports separate ATA requests queues for each IDE controller (one
queue per controller). The following structure contains information about
controller's queue and devices attached to the controller:
.. code-block:: c
/*
* This structure describes controller state, devices configuration on the
* controller and chain of ATA requests to the controller.
\*/
*/
typedef struct ata_ide_ctrl_s {
bool present; /* controller state \*/
ata_dev_t device[2]; /* ata devices description \*/
Chain_Control reqs; /* requests chain \*/
bool present; /* controller state */
ata_dev_t device[2]; /* ata devices description */
Chain_Control reqs; /* requests chain */
} ata_ide_ctrl_t;
Driver uses array of the structures indexed by the controllers minor
number.
Driver uses array of the structures indexed by the controllers minor number.
The following structure allows to map an ATA device to the pair (IDE
controller minor number device is attached to, device number
on the controller):
.. code:: c
The following structure allows to map an ATA device to the pair (IDE controller
minor number device is attached to, device number on the controller):
.. code-block:: c
/*
* Mapping of rtems ATA devices to the following pairs:
* (IDE controller number served the device, device number on the controller)
\*/
*/
typedef struct ata_ide_dev_s {
int ctrl_minor;/* minor number of IDE controller serves rtems ATA device \*/
int device; /* device number on IDE controller (0 or 1) \*/
int ctrl_minor;/* minor number of IDE controller serves rtems ATA device */
int device; /* device number on IDE controller (0 or 1) */
} ata_ide_dev_t;
Driver uses array of the structures indexed by the ATA devices minor
number.
Driver uses array of the structures indexed by the ATA devices minor number.
ATA driver defines the following internal events:
.. code:: c
/* ATA driver events \*/
.. code-block:: c
/* ATA driver events */
typedef enum ata_msg_type_s {
ATA_MSG_GEN_EVT = 1, /* general event \*/
ATA_MSG_SUCCESS_EVT, /* success event \*/
ATA_MSG_ERROR_EVT, /* error event \*/
ATA_MSG_PROCESS_NEXT_EVT /* process next ata request event \*/
ATA_MSG_GEN_EVT = 1, /* general event */
ATA_MSG_SUCCESS_EVT, /* success event */
ATA_MSG_ERROR_EVT, /* error event */
ATA_MSG_PROCESS_NEXT_EVT /* process next ata request event */
} ata_msg_type_t;
Brief ATA Driver Core Overview
------------------------------
All ATA driver functionality is available via ATA driver ioctl. Current
implementation supports only two ioctls: BLKIO_REQUEST and
ATAIO_SET_MULTIPLE_MODE. Each ATA driver ioctl() call generates an
ATA request which is appended to the appropriate controller queue depending
on ATA device the request belongs to. If appended request is single request in
the controller's queue then ATA driver event is generated.
implementation supports only two ioctls: ``BLKIO_REQUEST`` and
``ATAIO_SET_MULTIPLE_MODE``. Each ATA driver ``ioctl()`` call generates an ATA
request which is appended to the appropriate controller queue depending on ATA
device the request belongs to. If appended request is single request in the
controller's queue then ATA driver event is generated.
ATA driver task which manages queue of ATA driver events is core of ATA
driver. In current driver version queue of ATA driver events implemented
as RTEMS message queue. Each message contains event type, IDE controller
minor number on which event happened and error if an error occurred. Events
may be generated either by ATA driver ioctl call or by ATA driver task itself.
Each time ATA driver task receives an event it gets controller minor number
from event, takes first ATA request from controller queue and processes it
depending on request and event types. An ATA request processing may also
includes sending of several events. If ATA request processing is finished
the ATA request is removed from the controller queue. Note, that in current
implementation maximum one event per controller may be queued at any moment
of the time.
driver. In current driver version queue of ATA driver events implemented as
RTEMS message queue. Each message contains event type, IDE controller minor
number on which event happened and error if an error occurred. Events may be
generated either by ATA driver ioctl call or by ATA driver task itself. Each
time ATA driver task receives an event it gets controller minor number from
event, takes first ATA request from controller queue and processes it depending
on request and event types. An ATA request processing may also includes sending
of several events. If ATA request processing is finished the ATA request is
removed from the controller queue. Note, that in current implementation maximum
one event per controller may be queued at any moment of the time.
(This part seems not very clear, hope I rewrite it soon)
.. COMMENT: COPYRIGHT (c) 1988-2002.
.. COMMENT: On-Line Applications Research Corporation (OAR).
.. COMMENT: All rights reserved.

156
bsp_howto/clock.rst
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@ -1,5 +1,9 @@
.. comment SPDX-License-Identifier: CC-BY-SA-4.0
.. COMMENT: COPYRIGHT (c) 1988-2002.
.. COMMENT: On-Line Applications Research Corporation (OAR).
.. COMMENT: All rights reserved.
Clock Driver
############
@ -9,14 +13,16 @@ Introduction
The purpose of the clock driver is to provide two services for the operating
system.
- A steady time basis to the kernel, so that the RTEMS primitives that need
a clock tick work properly. See the *Clock Manager* chapter of the*RTEMS Application C User's Guide* for more details.
- A steady time basis to the kernel, so that the RTEMS primitives that need a
clock tick work properly. See the *Clock Manager* chapter of the *RTEMS
Application C User's Guide* for more details.
- An optional time counter to generate timestamps of the uptime and wall
clock time.
- An optional time counter to generate timestamps of the uptime and wall clock
time.
The clock driver is usually located in the :file:`clock` directory of the BSP.
Clock drivers should use the :dfn:`Clock Driver Shell` available via the:file:`clockdrv_shell.h` include file.
Clock drivers should use the :dfn:`Clock Driver Shell` available via the
:file:`clockdrv_shell.h` include file.
Clock Driver Shell
==================
@ -29,12 +35,13 @@ then the clock driver is registered and should provide its services to the
operating system. A hardware specific clock driver must provide some
functions, defines and macros for the :dfn:`Clock Driver Shell` which are
explained here step by step. A clock driver file looks in general like this.
.. code:: c
.. code-block:: c
/*
* A section with functions, defines and macros to provide hardware specific
* functions for the Clock Driver Shell.
\*/
*/
#include "../../../shared/clockdrv_shell.h"
Initialization
@ -45,9 +52,9 @@ must be selected.
- The most basic clock driver provides only a periodic interrupt service
routine which calls ``rtems_clock_tick()``. The interval is determined by
the application configuration via ``#define
CONFIGURE_MICROSECONDS_PER_TICK`` and can be obtained via``rtems_configuration_get_microseconds_per_tick()``. The timestamp
resolution is limited to the clock tick interval.
the application configuration via ``#define CONFIGURE_MICROSECONDS_PER_TICK``
and can be obtained via ``rtems_configuration_get_microseconds_per_tick()``.
The timestamp resolution is limited to the clock tick interval.
- In case the hardware lacks support for a free running counter, then the
module used for the clock tick may provide support for timestamps with a
@ -60,34 +67,42 @@ must be selected.
Clock Tick Only Variant
~~~~~~~~~~~~~~~~~~~~~~~
.. code:: c
.. code-block:: c
static void some_support_initialize_hardware( void )
{
/* Initialize hardware \*/
/* Initialize hardware */
}
#define Clock_driver_support_initialize_hardware() \\
#define Clock_driver_support_initialize_hardware() \
some_support_initialize_hardware()
/* Indicate that this clock driver lacks a proper timecounter in hardware \*/
/* Indicate that this clock driver lacks a proper timecounter in hardware */
#define CLOCK_DRIVER_USE_DUMMY_TIMECOUNTER
#include "../../../shared/clockdrv_shell.h"
Simple Timecounter Variant
~~~~~~~~~~~~~~~~~~~~~~~~~~
.. code:: c
.. code-block:: c
#include <rtems/timecounter.h>
static rtems_timecounter_simple some_tc;
static uint32_t some_tc_get( rtems_timecounter_simple \*tc )
static uint32_t some_tc_get( rtems_timecounter_simple *tc )
{
return some.counter;
}
static bool some_tc_is_pending( rtems_timecounter_simple \*tc )
static bool some_tc_is_pending( rtems_timecounter_simple *tc )
{
return some.is_pending;
}
static uint32_t some_tc_get_timecount( struct timecounter \*tc )
static uint32_t some_tc_get_timecount( struct timecounter *tc )
{
return rtems_timecounter_simple_downcounter_get(
tc,
@ -95,17 +110,20 @@ Simple Timecounter Variant
some_tc_is_pending
);
}
static void some_tc_tick( void )
{
rtems_timecounter_simple_downcounter_tick( &some_tc, some_tc_get );
}
static void some_support_initialize_hardware( void )
{
uint32_t frequency = 123456;
uint64_t us_per_tick = rtems_configuration_get_microseconds_per_tick();
uint32_t timecounter_ticks_per_clock_tick =
( frequency * us_per_tick ) / 1000000;
/* Initialize hardware \*/
/* Initialize hardware */
rtems_timecounter_simple_install(
&some_tc,
frequency,
@ -113,10 +131,12 @@ Simple Timecounter Variant
some_tc_get_timecount
);
}
#define Clock_driver_support_initialize_hardware() \\
#define Clock_driver_support_initialize_hardware() \
some_support_initialize_hardware()
#define Clock_driver_timecounter_tick() \\
#define Clock_driver_timecounter_tick() \
some_tc_tick()
#include "../../../shared/clockdrv_shell.h"
Timecounter Variant
@ -126,42 +146,52 @@ This variant is preferred since it is the most efficient and yields the most
accurate timestamps. It is also mandatory on SMP configurations to obtain
valid timestamps. The hardware must provide a periodic interrupt to service
the clock tick and a free running counter for the timecounter. The free
running counter must have a power of two period. The ``tc_counter_mask``
must be initialized to the free running counter period minus one, e.g. for a
32-bit counter this is 0xffffffff. The ``tc_get_timecount`` function must
return the current counter value (the counter values must increase, so if the
counter counts down, a conversion is necessary). Use``RTEMS_TIMECOUNTER_QUALITY_CLOCK_DRIVER`` for the ``tc_quality``. Set``tc_frequency`` to the frequency of the free running counter in Hz. All
other fields of the ``struct timecounter`` must be zero initialized.
Install the initialized timecounter via ``rtems_timecounter_install()``.
.. code:: c
running counter must have a power of two period. The ``tc_counter_mask`` must
be initialized to the free running counter period minus one, e.g. for a 32-bit
counter this is 0xffffffff. The ``tc_get_timecount`` function must return the
current counter value (the counter values must increase, so if the counter
counts down, a conversion is necessary). Use
``RTEMS_TIMECOUNTER_QUALITY_CLOCK_DRIVER`` for the ``tc_quality``. Set
``tc_frequency`` to the frequency of the free running counter in Hz. All other
fields of the ``struct timecounter`` must be zero initialized. Install the
initialized timecounter via ``rtems_timecounter_install()``.
.. code-block:: c
#include <rtems/timecounter.h>
static struct timecounter some_tc;
static uint32_t some_tc_get_timecount( struct timecounter \*tc )
static uint32_t some_tc_get_timecount( struct timecounter *tc )
{
some.free_running_counter;
}
static void some_support_initialize_hardware( void )
{
uint64_t us_per_tick = rtems_configuration_get_microseconds_per_tick();
uint32_t frequency = 123456;
/*
* The multiplication must be done in 64-bit arithmetic to avoid an integer
* overflow on targets with a high enough counter frequency.
\*/
*/
uint32_t interval = (uint32_t) ( ( frequency * us_per_tick ) / 1000000 );
/*
* Initialize hardware and set up a periodic interrupt for the configuration
* based interval.
\*/
*/
some_tc.tc_get_timecount = some_tc_get_timecount;
some_tc.tc_counter_mask = 0xffffffff;
some_tc.tc_frequency = frequency;
some_tc.tc_quality = RTEMS_TIMECOUNTER_QUALITY_CLOCK_DRIVER;
rtems_timecounter_install( &some_tc );
}
#define Clock_driver_support_initialize_hardware() \\
#define Clock_driver_support_initialize_hardware() \
some_support_initialize_hardware()
#include "../../../shared/clockdrv_shell.h"
Install Clock Tick Interrupt Service Routine
@ -169,10 +199,12 @@ Install Clock Tick Interrupt Service Routine
The clock driver must provide a function to install the clock tick interrupt
service routine via ``Clock_driver_support_install_isr()``.
.. code:: c
.. code-block:: c
#include <bsp/irq.h>
#include <bsp/fatal.h>
static void some_support_install_isr( rtems_interrupt_handler isr )
{
rtems_status_code sc;
@ -187,39 +219,50 @@ service routine via ``Clock_driver_support_install_isr()``.
bsp_fatal( SOME_FATAL_IRQ_INSTALL );
}
}
#define Clock_driver_support_install_isr( isr, old ) \\
#define Clock_driver_support_install_isr( isr, old ) \
some_support_install_isr( isr )
#include "../../../shared/clockdrv_shell.h"
Support At Tick
---------------
The hardware specific support at tick is specified by``Clock_driver_support_at_tick()``.
.. code:: c
The hardware specific support at tick is specified by
``Clock_driver_support_at_tick()``.
.. code-block:: c
static void some_support_at_tick( void )
{
/* Clear interrupt \*/
/* Clear interrupt */
}
#define Clock_driver_support_at_tick() \\
#define Clock_driver_support_at_tick() \
some_support_at_tick()
#include "../../../shared/clockdrv_shell.h"
System Shutdown Support
-----------------------
The :dfn:`Clock Driver Shell` provides the routine ``Clock_exit()`` that is
scheduled to be run during system shutdown via the ``atexit()`` routine.
The hardware specific shutdown support is specified by``Clock_driver_support_shutdown_hardware()`` which is used by``Clock_exit()``. It should disable the clock tick source if it was
enabled. This can be used to prevent clock ticks after the system is shutdown.
.. code:: c
scheduled to be run during system shutdown via the ``atexit()`` routine. The
hardware specific shutdown support is specified by
``Clock_driver_support_shutdown_hardware()`` which is used by ``Clock_exit()``.
It should disable the clock tick source if it was enabled. This can be used to
prevent clock ticks after the system is shutdown.
.. code-block:: c
static void some_support_shutdown_hardware( void )
{
/* Shutdown hardware \*/
/* Shutdown hardware */
}
#define Clock_driver_support_shutdown_hardware() \\
#define Clock_driver_support_shutdown_hardware() \
some_support_shutdown_hardware()
#include "../../../shared/clockdrv_shell.h"
Multiple Clock Driver Ticks Per Clock Tick
@ -228,14 +271,17 @@ Multiple Clock Driver Ticks Per Clock Tick
In case the hardware needs more than one clock driver tick per clock tick (e.g.
due to a limited range of the hardware timer), then this can be specified with
the optional ``#define CLOCK_DRIVER_ISRS_PER_TICK`` and ``#define
CLOCK_DRIVER_ISRS_PER_TICK_VALUE`` defines. This is currently used only for x86
and it hopefully remains that way.
.. code:: c
CLOCK_DRIVER_ISRS_PER_TICK_VALUE`` defines. This is currently used only for
x86 and it hopefully remains that way.
/* Enable multiple clock driver ticks per clock tick \*/
.. code-block:: c
/* Enable multiple clock driver ticks per clock tick */
#define CLOCK_DRIVER_ISRS_PER_TICK 1
/* Specifiy the clock driver ticks per clock tick value \*/
/* Specifiy the clock driver ticks per clock tick value */
#define CLOCK_DRIVER_ISRS_PER_TICK_VALUE 123
#include "../../../shared/clockdrv_shell.h"
Clock Driver Ticks Counter
@ -245,13 +291,7 @@ The :dfn:`Clock Driver Shell` provide a global variable that is simply a count
of the number of clock driver interrupt service routines that have occurred.
This information is valuable when debugging a system. This variable is
declared as follows:
.. code:: c
.. code-block:: c
volatile uint32_t Clock_driver_ticks;
.. COMMENT: COPYRIGHT (c) 1988-2002.
.. COMMENT: On-Line Applications Research Corporation (OAR).
.. COMMENT: All rights reserved.

9
bsp_howto/conf.py
View File

@ -3,10 +3,11 @@ sys.path.append(os.path.abspath('../common/'))
from conf import *
version = '1.0'
release = '5.0'
version = '4.11.0'
release = '4.11.0'
project = "RTEMS BSP and Device Driver Development Guide"
latex_documents = [
('index', 'bsp_howto.tex', u'RTEMS BSP Howto Documentation', u'RTEMS Documentation Project', 'manual'),
('index', 'bsp_howto.tex', u'RTEMS BSP and Device Driver Development Guide', u'RTEMS Documentation Project', 'manual'),
]

375
bsp_howto/console.rst
View File

@ -1,51 +1,53 @@
.. comment SPDX-License-Identifier: CC-BY-SA-4.0
.. COMMENT: COPYRIGHT (c) 1988-2002.
.. COMMENT: On-Line Applications Research Corporation (OAR).
.. COMMENT: All rights reserved.
Console Driver
##############
Introduction
============
This chapter describes the operation of a console driver using
the RTEMS POSIX Termios support. Traditionally RTEMS has referred
to all serial device drivers as console device drivers. A
console driver can be used to do raw data processing in addition
to the "normal" standard input and output device functions required
of a console.
This chapter describes the operation of a console driver using the RTEMS POSIX
Termios support. Traditionally RTEMS has referred to all serial device drivers
as console device drivers. A console driver can be used to do raw data
processing in addition to the "normal" standard input and output device
functions required of a console.
The serial driver may be called as the consequence of a C Library
call such as ``printf`` or ``scanf`` or directly via the``read`` or ``write`` system calls.
The serial driver may be called as the consequence of a C Library call such as
``printf`` or ``scanf`` or directly via the``read`` or ``write`` system calls.
There are two main functioning modes:
- console: formatted input/output, with special characters (end of
line, tabulations, etc.) recognition and processing,
- console: formatted input/output, with special characters (end of line,
tabulations, etc.) recognition and processing,
- raw: permits raw data processing.
One may think that two serial drivers are needed to handle these two types
of data, but Termios permits having only one driver.
One may think that two serial drivers are needed to handle these two types of
data, but Termios permits having only one driver.
Termios
=======
Termios is a standard for terminal management, included in the POSIX
1003.1b standard. As part of the POSIX and Open Group Single UNIX
Specification, is commonly provided on UNIX implementations. The
Open Group has the termios portion of the POSIX standard online
at http://opengroup.org/onlinepubs/007908775/xbd/termios.html.
The requirements for the ``<termios.h>`` file are also provided
and are at http://opengroup.org/onlinepubs/007908775/xsh/termios.h.html.
Termios is a standard for terminal management, included in the POSIX 1003.1b
standard. As part of the POSIX and Open Group Single UNIX Specification, is
commonly provided on UNIX implementations. The Open Group has the termios
portion of the POSIX standard online at
http://opengroup.org/onlinepubs/007908775/xbd/termios.html. The requirements
for the ``<termios.h>`` file are also provided and are at
http://opengroup.org/onlinepubs/007908775/xsh/termios.h.html.
Having RTEMS support for Termios is beneficial because:
- from the user's side because it provides standard primitive operations
to access the terminal and change configuration settings. These operations
are the same under UNIX and RTEMS.
- from the user's side because it provides standard primitive operations to
access the terminal and change configuration settings. These operations are
the same under UNIX and RTEMS.
- from the BSP developer's side because it frees the
developer from dealing with buffer states and mutual exclusions on them.
Early RTEMS console device drivers also did their own special
character processing.
- from the BSP developer's side because it frees the developer from dealing
with buffer states and mutual exclusions on them. Early RTEMS console device
drivers also did their own special character processing.
- it is part of an internationally recognized standard.
@ -55,13 +57,11 @@ Termios support includes:
- raw and console handling,
- blocking or non-blocking characters receive, with or without
Timeout.
- blocking or non-blocking characters receive, with or without Timeout.
At this time, RTEMS documentation does not include a thorough discussion
of the Termios functionality. For more information on Termios,
type ``man termios`` on a Unix box or point a web browser
athttp://www.freebsd.org/cgi/man.cgi.
At this time, RTEMS documentation does not include a thorough discussion of the
Termios functionality. For more information on Termios, type ``man termios``
on a Unix box or point a web browser athttp://www.freebsd.org/cgi/man.cgi.
Driver Functioning Modes
========================
@ -75,37 +75,34 @@ Asynchronous Receiver-Transmitter, i.e. the serial chip):
- task driven mode
In polled mode, the processor blocks on sending/receiving characters.
This mode is not the most efficient way to utilize the UART. But
polled mode is usually necessary when one wants to print an
error message in the event of a fatal error such as a fatal error
in the BSP. This is also the simplest mode to
program. Polled mode is generally preferred if the serial port is
to be used primarily as a debug console. In a simple polled driver,
the software will continuously check the status of the UART when
it is reading or writing to the UART. Termios improves on this
by delaying the caller for 1 clock tick between successive checks
of the UART on a read operation.
In polled mode, the processor blocks on sending/receiving characters. This
mode is not the most efficient way to utilize the UART. But polled mode is
usually necessary when one wants to print an error message in the event of a
fatal error such as a fatal error in the BSP. This is also the simplest mode
to program. Polled mode is generally preferred if the serial port is to be
used primarily as a debug console. In a simple polled driver, the software
will continuously check the status of the UART when it is reading or writing to
the UART. Termios improves on this by delaying the caller for 1 clock tick
between successive checks of the UART on a read operation.
In interrupt driven mode, the processor does not block on sending/receiving
characters. Data is buffered between the interrupt service routine
and application code. Two buffers are used to insulate the application
from the relative slowness of the serial device. One of the buffers is
used for incoming characters, while the other is used for outgoing characters.
characters. Data is buffered between the interrupt service routine and
application code. Two buffers are used to insulate the application from the
relative slowness of the serial device. One of the buffers is used for
incoming characters, while the other is used for outgoing characters.
An interrupt is raised when a character is received by the UART.
The interrupt subroutine places the incoming character at the end
of the input buffer. When an application asks for input,
the characters at the front of the buffer are returned.
An interrupt is raised when a character is received by the UART. The interrupt
subroutine places the incoming character at the end of the input buffer. When
an application asks for input, the characters at the front of the buffer are
returned.
When the application prints to the serial device, the outgoing characters
are placed at the end of the output buffer. The driver will place
one or more characters in the UART (the exact number depends on the UART)
An interrupt will be raised when all the characters have been transmitted.
The interrupt service routine has to send the characters
remaining in the output buffer the same way. When the transmitting side
of the UART is idle, it is typically necessary to prime the transmitter
before the first interrupt will occur.
When the application prints to the serial device, the outgoing characters are
placed at the end of the output buffer. The driver will place one or more
characters in the UART (the exact number depends on the UART) An interrupt will
be raised when all the characters have been transmitted. The interrupt service
routine has to send the characters remaining in the output buffer the same way.
When the transmitting side of the UART is idle, it is typically necessary to
prime the transmitter before the first interrupt will occur.
The task driven mode is similar to interrupt driven mode, but the actual data
processing is done in dedicated tasks instead of interrupt routines.
@ -113,16 +110,17 @@ processing is done in dedicated tasks instead of interrupt routines.
Serial Driver Functioning Overview
==================================
The following Figure shows how a Termios driven serial driver works:
Figure not included in ASCII version
The following Figure shows how a Termios driven serial driver works: Figure not
included in ASCII version
The following list describes the basic flow.
- the application programmer uses standard C library call (printf,
scanf, read, write, etc.),
- the application programmer uses standard C library call (printf, scanf, read,
write, etc.),
- C library (ctx.g. RedHat (formerly Cygnus) Newlib) calls
the RTEMS system call interface. This code can be found in the:file:`cpukit/libcsupport/src` directory.
- C library (ctx.g. RedHat (formerly Cygnus) Newlib) calls the RTEMS system
call interface. This code can be found in the:file:`cpukit/libcsupport/src`
directory.
- Glue code calls the serial driver entry routines.
@ -133,31 +131,30 @@ The low-level driver API changed between RTEMS 4.10 and RTEMS 4.11. The legacy
callback API is still supported, but its use is discouraged. The following
functions are deprecated:
- ``rtems_termios_open()`` - use ``rtems_termios_device_open()`` in
combination with ``rtems_termios_device_install()`` instead.
- ``rtems_termios_open()`` - use ``rtems_termios_device_open()`` in combination
with ``rtems_termios_device_install()`` instead.
- ``rtems_termios_close()`` - use ``rtems_termios_device_close()``
instead.
- ``rtems_termios_close()`` - use ``rtems_termios_device_close()`` instead.
This manual describes the new API. A new console driver should consist of
three parts.
# The basic console driver functions using the Termios support. Add this
the BSPs Makefile.am:
- The basic console driver functions using the Termios support. Add this the
BSPs Makefile.am:
.. code:: c
.. code-block:: makefile
[...]
libbsp_a_SOURCES += ../../shared/console-termios.c
\[...]
[...]
# A general serial module specific low-level driver providing the handler
table for the Termios ``rtems_termios_device_install()`` function. This
low-level driver could be used for more than one BSP.
- A general serial module specific low-level driver providing the handler table
for the Termios ``rtems_termios_device_install()`` function. This low-level
driver could be used for more than one BSP.
# A BSP specific initialization routine ``console_initialize()``, that
calls ``rtems_termios_device_install()`` providing a low-level driver
context for each installed device.
- A BSP specific initialization routine ``console_initialize()``, that calls
``rtems_termios_device_install()`` providing a low-level driver context for
each installed device.
You need to provide a device handler structure for the Termios device
interface. The functions are described later in this chapter. The first open
@ -167,9 +164,11 @@ case one is available or minus one otherwise.
If you want to use polled IO it should look like the following. Termios must
be told the addresses of the handler that are to be used for simple character
IO, i.e. pointers to the ``my_driver_poll_read()`` and``my_driver_poll_write()`` functions described later in `Termios and Polled IO`_.
IO, i.e. pointers to the ``my_driver_poll_read()`` and
``my_driver_poll_write()`` functions described later in `Termios and Polled
IO`_.
.. code:: c
.. code-block:: c
const rtems_termios_handler my_driver_handler_polled = {
.first_open = my_driver_first_open,
@ -187,9 +186,10 @@ functioning is quite different in this mode. There is no device driver read
handler to be passed to Termios. Indeed a ``console_read()`` call returns the
contents of Termios input buffer. This buffer is filled in the driver
interrupt subroutine, see also `Termios and Interrupt Driven IO`_. The driver
is responsible for providing a pointer to the``my_driver_interrupt_write()`` function.
is responsible for providing a pointer to the``my_driver_interrupt_write()``
function.
.. code:: c
.. code-block:: c
const rtems_termios_handler my_driver_handler_interrupt = {
.first_open = my_driver_first_open,
@ -203,19 +203,23 @@ is responsible for providing a pointer to the``my_driver_interrupt_write()`` fun
.mode = TERMIOS_IRQ_DRIVEN
};
You can also provide hander for remote transmission control. This
is not covered in this manual, so they are set to ``NULL`` in the above
examples.
You can also provide hander for remote transmission control. This is not
covered in this manual, so they are set to ``NULL`` in the above examples.
The low-level driver should provide a data structure for its device context.
The initialization routine must provide a context for each installed device via``rtems_termios_device_install()``. For simplicity of the console
initialization example the device name is also present. Her is an example header file.
.. code:: c
The initialization routine must provide a context for each installed device via
``rtems_termios_device_install()``. For simplicity of the console
initialization example the device name is also present. Here is an example
header file.
.. code-block:: c
#ifndef MY_DRIVER_H
#define MY_DRIVER_H
#include <rtems/termiostypes.h>
#include <some-chip-header.h>
/* Low-level driver specific data structure \*/
typedef struct {
rtems_termios_device_context base;
@ -223,10 +227,11 @@ initialization example the device name is also present. Her is an example heade
volatile module_register_block \*regs;
/* More stuff \*/
} my_driver_context;
extern const rtems_termios_handler my_driver_handler_polled;
extern const rtems_termios_handler my_driver_handler_interrupt;
#endif /* MY_DRIVER_H \*/
#endif /* MY_DRIVER_H \*/
Termios and Polled IO
---------------------
@ -236,17 +241,18 @@ Termios for simple character IO.
The ``my_driver_poll_write()`` routine is responsible for writing ``n``
characters from ``buf`` to the serial device specified by ``tty``.
.. code:: c
.. code-block:: c
static void my_driver_poll_write(
rtems_termios_device_context \*base,
const char \*buf,
rtems_termios_device_context *base,
const char *buf,
size_t n
)
{
my_driver_context \*ctx = (my_driver_context \*) base;
my_driver_context *ctx = (my_driver_context *) base;
size_t i;
/* Write \*/
/* Write */
for (i = 0; i < n; ++i) {
my_driver_write_char(ctx, buf[i]);
}
@ -255,17 +261,18 @@ characters from ``buf`` to the serial device specified by ``tty``.
The ``my_driver_poll_read`` routine is responsible for reading a single
character from the serial device specified by ``tty``. If no character is
available, then the routine should return minus one.
.. code:: c
static int my_driver_poll_read(rtems_termios_device_context \*base)
.. code-block:: c
static int my_driver_poll_read(rtems_termios_device_context *base)
{
my_driver_context \*ctx = (my_driver_context \*) base;
/* Check if a character is available \*/
my_driver_context *ctx = (my_driver_context *) base;
/* Check if a character is available */
if (my_driver_can_read_char(ctx)) {
/* Return the character \*/
/* Return the character */
return my_driver_read_char(ctx);
} else {
/* Return an error status \*/
/* Return an error status */
return -1;
}
}
@ -285,65 +292,70 @@ transmitter is ready for another character.
In the simplest case, the ``my_driver_interrupt_handler()`` will have to check
the status of the UART and determine what caused the interrupt. The following
describes the operation of an ``my_driver_interrupt_handler`` which has to
do this:
.. code:: c
describes the operation of an ``my_driver_interrupt_handler`` which has to do
this:
.. code-block:: c
static void my_driver_interrupt_handler(
rtems_vector_number vector,
void \*arg
void *arg
)
{
rtems_termios_tty \*tty = arg;
my_driver_context \*ctx = rtems_termios_get_device_context(tty);
rtems_termios_tty *tty = arg;
my_driver_context *ctx = rtems_termios_get_device_context(tty);
char buf[N];
size_t n;
/*
* Check if we have received something. The function reads the
* received characters from the device and stores them in the
* buffer. It returns the number of read characters.
\*/
*/
n = my_driver_read_received_chars(ctx, buf, N);
if (n > 0) {
/* Hand the data over to the Termios infrastructure \*/
/* Hand the data over to the Termios infrastructure */
rtems_termios_enqueue_raw_characters(tty, buf, n);
}
/*
* Check if we have something transmitted. The functions returns
* the number of transmitted characters since the last write to the
* device.
\*/
*/
n = my_driver_transmitted_chars(ctx);
if (n > 0) {
/*
* Notify Termios that we have transmitted some characters. It
* will call now the interrupt write function if more characters
* are ready for transmission.
\*/
*/
rtems_termios_dequeue_characters(tty, n);
}
}
The ``my_driver_interrupt_write()`` function is responsible for telling the
device that the ``n`` characters at ``buf`` are to be transmitted. It
the value ``n`` is zero to indicate that no more characters are to send.
The driver can disable the transmit interrupts now. This routine is invoked
either from task context with disabled interrupts to start a new transmission
process with exactly one character in case of an idle output state or from the
device that the ``n`` characters at ``buf`` are to be transmitted. It the
value ``n`` is zero to indicate that no more characters are to send. The
driver can disable the transmit interrupts now. This routine is invoked either
from task context with disabled interrupts to start a new transmission process
with exactly one character in case of an idle output state or from the
interrupt handler to refill the transmitter. If the routine is invoked to
start the transmit process the output state will become busy and Termios starts
to fill the output buffer. If the transmit interrupt arises before Termios was
able to fill the transmit buffer you will end up with one interrupt per
character.
.. code:: c
.. code-block:: c
static void my_driver_interrupt_write(
rtems_termios_device_context \*base,
const char \*buf,
rtems_termios_device_context *base,
const char *buf,
size_t n
)
{
my_driver_context \*ctx = (my_driver_context \*) base;
my_driver_context *ctx = (my_driver_context *) base;
/*
* Tell the device to transmit some characters from buf (less than
* or equal to n). When the device is finished it should raise an
@ -351,12 +363,12 @@ character.
* characters have been transmitted and this may trigger this write
* function again. You may have to store the number of outstanding
* characters in the device data structure.
\*/
*/
/*
* Termios will set n to zero to indicate that the transmitter is
* now inactive. The output buffer is empty in this case. The
* driver may disable the transmit interrupts now.
\*/
*/
}
Initialization
@ -366,44 +378,50 @@ The BSP specific driver initialization is called once during the RTEMS
initialization process.
The ``console_initialize()`` function may look like this:
.. code:: c
.. code-block:: c
#include <my-driver.h>
#include <rtems/console.h>
#include <bsp.h>
#include <bsp/fatal.h>
static my_driver_context driver_context_table[M] = { /* Some values \*/ };
static my_driver_context driver_context_table[M] = { /* Some values */ };
rtems_device_driver console_initialize(
rtems_device_major_number major,
rtems_device_minor_number minor,
void \*arg
void *arg
)
{
rtems_status_code sc;
#ifdef SOME_BSP_USE_INTERRUPTS
const rtems_termios_handler \*handler = &my_driver_handler_interrupt;
const rtems_termios_handler *handler = &my_driver_handler_interrupt;
#else
const rtems_termios_handler \*handler = &my_driver_handler_polled;
const rtems_termios_handler *handler = &my_driver_handler_polled;
#endif
/*
* Initialize the Termios infrastructure. If Termios has already
* been initialized by another device driver, then this call will
* have no effect.
\*/
*/
rtems_termios_initialize();
/* Initialize each device \*/
/* Initialize each device */
for (
minor = 0;
minor < RTEMS_ARRAY_SIZE(driver_context_table);
++minor
) {
my_driver_context \*ctx = &driver_context_table[minor];
my_driver_context *ctx = &driver_context_table[minor];
/*
* Install this device in the file system and Termios. In order
* to use the console (i.e. being able to do printf, scanf etc.
* on stdin, stdout and stderr), one device must be registered as
* "/dev/console" (CONSOLE_DEVICE_NAME).
\*/
*/
sc = rtems_termios_device_install(
ctx->device_name,
major,
@ -416,58 +434,68 @@ The ``console_initialize()`` function may look like this:
bsp_fatal(SOME_BSP_FATAL_CONSOLE_DEVICE_INSTALL);
}
}
return RTEMS_SUCCESSFUL;
}
Opening a serial device
-----------------------
The ``console_open()`` function provided by :file:`console-termios.c` is
called whenever a serial device is opened. The device registered as``"/dev/console"`` (``CONSOLE_DEVICE_NAME``) is opened automatically
during RTEMS initialization. For instance, if UART channel 2 is registered as``"/dev/tty1"``, the ``console_open()`` entry point will be called as the
The ``console_open()`` function provided by :file:`console-termios.c` is called
whenever a serial device is opened. The device registered as
``"/dev/console"`` (``CONSOLE_DEVICE_NAME``) is opened automatically during
RTEMS initialization. For instance, if UART channel 2 is registered as
``"/dev/tty1"``, the ``console_open()`` entry point will be called as the
result of an ``fopen("/dev/tty1", mode)`` in the application.
During the first open of the device Termios will call the``my_driver_first_open()`` handler.
.. code:: c
During the first open of the device Termios will call the
``my_driver_first_open()`` handler.
.. code-block:: c
static bool my_driver_first_open(
rtems_termios_tty \*tty,
rtems_termios_device_context \*base,
struct termios \*term,
rtems_libio_open_close_args_t \*args
rtems_termios_tty *tty,
rtems_termios_device_context *base,
struct termios *term,
rtems_libio_open_close_args_t *args
)
{
my_driver_context \*ctx = (my_driver_context \*) base;
my_driver_context *ctx = (my_driver_context *) base;
rtems_status_code sc;
bool ok;
/*
* You may add some initialization code here.
\*/
*/
/*
* Sets the initial baud rate. This should be set to the value of
* the boot loader. This function accepts only exact Termios baud
* values.
\*/
*/
sc = rtems_termios_set_initial_baud(tty, MY_DRIVER_BAUD_RATE);
if (sc != RTEMS_SUCCESSFUL) {
/* Not a valid Termios baud \*/
/* Not a valid Termios baud */
}
/*
* Alternatively you can set the best baud.
\*/
*/
rtems_termios_set_best_baud(term, MY_DRIVER_BAUD_RATE);
/*
* To propagate the initial Termios attributes to the device use
* this.
\*/
*/
ok = my_driver_set_attributes(base, term);
if (!ok) {
/* This is bad \*/
/* This is bad */
}
/*
* Return true to indicate a successful set attributes, and false
* otherwise.
\*/
*/
return true;
}
@ -480,18 +508,20 @@ driver close entry point.
Termios will call the ``my_driver_last_close()`` handler if the last close
happens on the device.
.. code:: c
.. code-block:: c
static void my_driver_last_close(
rtems_termios_tty \*tty,
rtems_termios_device_context \*base,
rtems_libio_open_close_args_t \*args
rtems_termios_tty *tty,
rtems_termios_device_context *base,
rtems_libio_open_close_args_t *args
)
{
my_driver_context \*ctx = (my_driver_context \*) base;
my_driver_context *ctx = (my_driver_context *) base;
/*
* The driver may do some cleanup here.
\*/
*/
}
Reading Characters from a Serial Device
@ -511,44 +541,39 @@ device driver write entry point.
Changing Serial Line Parameters
-------------------------------
The ``console_control()`` provided by :file:`console-termios.c` is invoked
when the line parameters for a particular serial device are to be changed.
This entry point corresponds to the device driver IO control entry point.
The ``console_control()`` provided by :file:`console-termios.c` is invoked when
the line parameters for a particular serial device are to be changed. This
entry point corresponds to the device driver IO control entry point.
The application writer is able to control the serial line configuration with
Termios calls (such as the ``ioctl()`` command, see the Termios
documentation for more details). If the driver is to support dynamic
configuration, then it must have the ``console_control()`` piece of code.
Basically ``ioctl()`` commands call ``console_control()`` with the serial
line configuration in a Termios defined data structure.
Termios calls (such as the ``ioctl()`` command, see the Termios documentation
for more details). If the driver is to support dynamic configuration, then it
must have the ``console_control()`` piece of code. Basically ``ioctl()``
commands call ``console_control()`` with the serial line configuration in a
Termios defined data structure.
The driver is responsible for reinitializing the device with the correct
settings. For this purpose Termios calls the ``my_driver_set_attributes()``
handler.
.. code:: c
.. code-block:: c
static bool my_driver_set_attributes(
rtems_termios_device_context \*base,
const struct termios \*term
rtems_termios_device_context *base,
const struct termios *term
)
{
my_driver_context \*ctx = (my_driver_context \*) base;
my_driver_context *ctx = (my_driver_context *) base;
/*
* Inspect the termios data structure and configure the device
* appropriately. The driver should only be concerned with the
* parts of the structure that specify hardware setting for the
* communications channel such as baud, character size, etc.
\*/
*/
/*
* Return true to indicate a successful set attributes, and false
* otherwise.
\*/
*/
return true;
}
.. COMMENT: COPYRIGHT (c) 1988-2002.
.. COMMENT: On-Line Applications Research Corporation (OAR).
.. COMMENT: All rights reserved.

187
bsp_howto/discrete.rst
View File

@ -3,9 +3,8 @@
Discrete Driver
###############
The Discrete driver is responsible for providing an
interface to Discrete Input/Outputs. The capabilities provided
by this class of device driver are:
The Discrete driver is responsible for providing an interface to Discrete
Input/Outputs. The capabilities provided by this class of device driver are:
- Initialize a Discrete I/O Board
@ -21,76 +20,73 @@ by this class of device driver are:
- Reinitialize DACS
Most discrete I/O devices are found on I/O cards that support many
bits of discrete I/O on a single card. This driver model is centered
on the notion of reading bitfields from the card.
Most discrete I/O devices are found on I/O cards that support many bits of
discrete I/O on a single card. This driver model is centered on the notion of
reading bitfields from the card.
There are currently no discrete I/O device drivers included in the
RTEMS source tree. The information provided in this chapter
is based on drivers developed for applications using RTEMS.
It is hoped that this driver model information can form the
discrete I/O driver model that can be supported in future RTEMS
There are currently no discrete I/O device drivers included in the RTEMS source
tree. The information provided in this chapter is based on drivers developed
for applications using RTEMS. It is hoped that this driver model information
can form the discrete I/O driver model that can be supported in future RTEMS
distribution.
Major and Minor Numbers
=======================
The *major* number of a device driver is its index in the
RTEMS Device Address Table.
The ``major`` number of a device driver is its index in the RTEMS Device
Address Table.
A *minor* number is associated with each device instance
managed by a particular device driver. An RTEMS minor number
is an ``unsigned32`` entity. Convention calls for
dividing the bits in the minor number down into categories
that specify a particular bitfield. This results in categories
like the following:
A ``minor`` number is associated with each device instance managed by a
particular device driver. An RTEMS minor number is an ``unsigned32`` entity.
Convention calls for dividing the bits in the minor number down into categories
that specify a particular bitfield. This results in categories like the
following:
- *board* - indicates the board a particular bitfield is located on
- ``board`` - indicates the board a particular bitfield is located on
- *word* - indicates the particular word of discrete bits the
bitfield is located within
- ``word`` - indicates the particular word of discrete bits the bitfield is
located within
- *start* - indicates the starting bit of the bitfield
- ``start`` - indicates the starting bit of the bitfield
- *width* - indicates the width of the bitfield
- ``width`` - indicates the width of the bitfield
From the above, it should be clear that a single device driver
can support multiple copies of the same board in a single system.
The minor number is used to distinguish the devices.
From the above, it should be clear that a single device driver can support
multiple copies of the same board in a single system. The minor number is used
to distinguish the devices.
By providing a way to easily access a particular bitfield from
the device driver, the application is insulated with knowing how
to mask fields in and out of a discrete I/O.
By providing a way to easily access a particular bitfield from the device
driver, the application is insulated with knowing how to mask fields in and out
of a discrete I/O.
Discrete I/O Driver Configuration
=================================
There is not a standard discrete I/O driver configuration table but some
fields are common across different drivers. The discrete I/O driver
configuration table is typically an array of structures with each
structure containing the information for a particular board.
The following is a list of the type of information normally required
to configure an discrete I/O board:
There is not a standard discrete I/O driver configuration table but some fields
are common across different drivers. The discrete I/O driver configuration
table is typically an array of structures with each structure containing the
information for a particular board. The following is a list of the type of
information normally required to configure an discrete I/O board:
*board_offset*
``board_offset``
is the base address of a board.
*relay_initial_values*
is an array of the values that should be written to each output
word on the board during initialization. This allows the driver
to start with the board's output in a known state.
``relay_initial_values``
is an array of the values that should be written to each output word on the
board during initialization. This allows the driver to start with the
board's output in a known state.
Initialize a Discrete I/O Board
===============================
At system initialization, the discrete I/O driver's initialization entry point
will be invoked. As part of initialization, the driver will perform
whatever board initializatin is required and then set all
outputs to their configured initial state.
will be invoked. As part of initialization, the driver will perform whatever
board initializatin is required and then set all outputs to their configured
initial state.
The discrete I/O driver may register a device name for bitfields of
particular interest to the system. Normally this will be restricted
to the names of each word and, if the driver supports it, an "all words".
The discrete I/O driver may register a device name for bitfields of particular
interest to the system. Normally this will be restricted to the names of each
word and, if the driver supports it, an "all words".
Open a Particular Discrete Bitfield
===================================
@ -99,8 +95,8 @@ This is the driver open call. Usually this call does nothing other than
validate the minor number.
With some drivers, it may be necessary to allocate memory when a particular
device is opened. If that is the case, then this is often the place
to do this operation.
device is opened. If that is the case, then this is often the place to do this
operation.
Close a Particular Discrete Bitfield
====================================
@ -108,82 +104,87 @@ Close a Particular Discrete Bitfield
This is the driver close call. Usually this call does nothing.
With some drivers, it may be necessary to allocate memory when a particular
device is opened. If that is the case, then this is the place
where that memory should be deallocated.
device is opened. If that is the case, then this is the place where that
memory should be deallocated.
Read from a Particular Discrete Bitfield
========================================
This corresponds to the driver read call. After validating the minor
number and arguments, this call reads the indicated bitfield. A
discrete I/O devices may have to store the last value written to
a discrete output. If the bitfield is output only, saving the last
written value gives the appearance that it can be read from also.
If the bitfield is input, then it is sampled.
This corresponds to the driver read call. After validating the minor number
and arguments, this call reads the indicated bitfield. A discrete I/O devices
may have to store the last value written to a discrete output. If the bitfield
is output only, saving the last written value gives the appearance that it can
be read from also. If the bitfield is input, then it is sampled.
*NOTE:* Many discrete inputs have a tendency to bounce. The application
may have to take account for bounces.
.. note::
The value returned is an ``unsigned32`` number
representing the bitfield read. This value is stored in the``argument_block`` passed in to the call.
Many discrete inputs have a tendency to bounce. The application may have to
take account for bounces.
*NOTE:* Some discrete I/O drivers have a special minor number
used to access all discrete I/O bits on the board. If this special
minor is used, then the area pointed to by ``argument_block`` must
be the correct size.
The value returned is an ``unsigned32`` number representing the bitfield read.
This value is stored in the ``argument_block`` passed in to the call.
.. note::
Some discrete I/O drivers have a special minor number used to access all
discrete I/O bits on the board. If this special minor is used, then the
area pointed to by ``argument_block`` must be the correct size.
Write to a Particular Discrete Bitfield
=======================================
This corresponds to the driver write call. After validating the minor
number and arguments, this call writes the indicated device. If the
specified device is an ADC, then an error is usually returned.
This corresponds to the driver write call. After validating the minor number
and arguments, this call writes the indicated device. If the specified device
is an ADC, then an error is usually returned.
The value written is an ``unsigned32`` number
representing the value to be written to the specified
bitfield. This value is stored in the``argument_block`` passed in to the call.
The value written is an ``unsigned32`` number representing the value to be
written to the specified bitfield. This value is stored in the
``argument_block`` passed in to the call.
*NOTE:* Some discrete I/O drivers have a special minor number
used to access all discrete I/O bits on the board. If this special
minor is used, then the area pointed to by ``argument_block`` must
be the correct size.
.. note::
Some discrete I/O drivers have a special minor number used to access all
discrete I/O bits on the board. If this special minor is used, then the
area pointed to by ``argument_block`` must be the correct size.
Disable Discrete Outputs
========================
This is one of the IOCTL functions supported by the I/O control
device driver entry point. When this IOCTL function is invoked,
the discrete outputs are disabled.
This is one of the IOCTL functions supported by the I/O control device driver
entry point. When this IOCTL function is invoked, the discrete outputs are
disabled.
*NOTE:* It may not be possible to disable/enable discrete output on all
discrete I/O boards.
.. note::
It may not be possible to disable/enable discrete output on all discrete I/O
boards.
Enable Discrete Outputs
=======================
This is one of the IOCTL functions supported by the I/O control
device driver entry point. When this IOCTL function is invoked,
the discrete outputs are enabled.
This is one of the IOCTL functions supported by the I/O control device driver
entry point. When this IOCTL function is invoked, the discrete outputs are
enabled.
*NOTE:* It may not be possible to disable/enable discrete output on all
discrete I/O boards.
.. note::
It may not be possible to disable/enable discrete output on all discrete
I/O boards.
Reinitialize Outputs
====================
This is one of the IOCTL functions supported by the I/O control
device driver entry point. When this IOCTL function is invoked,
the discrete outputs are rewritten with the configured initial
output values.
This is one of the IOCTL functions supported by the I/O control device driver
entry point. When this IOCTL function is invoked, the discrete outputs are
rewritten with the configured initial output values.
Get Last Written Values
=======================
This is one of the IOCTL functions supported by the I/O control
device driver entry point. When this IOCTL function is invoked,
the following information is returned to the caller:
This is one of the IOCTL functions supported by the I/O control device driver
entry point. When this IOCTL function is invoked, the following information is
returned to the caller:
- last value written to the specified output word
- timestamp of when the last write was performed

187
bsp_howto/frame_buffer.rst
View File

@ -1,29 +1,40 @@
.. comment SPDX-License-Identifier: CC-BY-SA-4.0
.. COMMENT: COPYRIGHT (c) 1988-2002.
.. COMMENT: On-Line Applications Research Corporation (OAR).
.. COMMENT: All rights reserved.
Frame Buffer Driver
###################
In this chapter, we present the basic functionality implemented by a
frame buffer driver: ``frame_buffer_initialize()``, ``frame_buffer_open()``,``frame_buffer_close()``, ``frame_buffer_read()``, ``frame_buffer_write()``
and ``frame_buffer_control()``.
In this chapter, we present the basic functionality implemented by a frame
buffer driver:
- ``frame_buffer_initialize()``
- ``frame_buffer_open()``
- ``frame_buffer_close()``
- ``frame_buffer_read()``
- ``frame_buffer_write()``
- ``frame_buffer_control()``
Introduction
============
The purpose of the frame buffer driver is to provide an abstraction for
graphics hardware.
By using the frame buffer interface, an application can display graphics
without knowing anything about the low-level details of interfacing to a
particular graphics adapter. The parameters governing the mapping of
memory to displayed pixels (planar or linear, bit depth, etc) is still
implementation-specific, but device-independent methods are provided to
graphics hardware. By using the frame buffer interface, an application can
display graphics without knowing anything about the low-level details of
interfacing to a particular graphics adapter. The parameters governing the
mapping of memory to displayed pixels (planar or linear, bit depth, etc) is
still implementation-specific, but device-independent methods are provided to
determine and potentially modify these parameters.
The frame buffer driver is commonly located in the ``console``
directory of the BSP and registered by the name */dev/fb0*.
Additional frame buffers (if available) are named */dev/fb1*,*/dev/fb2*, etc.
The frame buffer driver is commonly located in the ``console`` directory of the
BSP and registered by the name :file:`/dev/fb0`. Additional frame buffers (if
available) are named :file:`/dev/fb1*,*/dev/fb2`, etc.
To work with the frame buffer, the following operation sequence is used:``open()``, ``ioctls()`` to get the frame buffer info, ``read()`` and/or``write()``, and ``close()``.
To work with the frame buffer, the following operation sequence is
used:``open()``, ``ioctls()`` to get the frame buffer info, ``read()``
and/or ``write()``, and ``close()``.
Driver Function Overview
========================
@ -32,66 +43,74 @@ Initialization
--------------
The driver initialization is called once during the RTEMS initialization
process and returns RTEMS_SUCCESSFUL when the device driver is successfully
initialized. During the initialization, a name is assigned to the frame
buffer device. If the graphics hardware supports console text output,
as is the case with the pc386 VGA hardware, initialization into graphics
mode may be deferred until the device is ``open()`` ed.
process and returns ``RTEMS_SUCCESSFUL`` when the device driver is successfully
initialized. During the initialization, a name is assigned to the frame buffer
device. If the graphics hardware supports console text output, as is the case
with the pc386 VGA hardware, initialization into graphics mode may be deferred
until the device is ``open()`` ed.
The ``frame_buffer_initialize()`` function may look like this:
.. code:: c
.. code-block:: c
rtems_device_driver frame_buffer_initialize(
rtems_device_major_number major,
rtems_device_minor_number minor,
void \*arg)
void *arg)
{
rtems_status_code status;
printk( "frame buffer driver initializing..\\n" );
printk( "frame buffer driver initializing..\n" );
/*
* Register the device
\*/
*/
status = rtems_io_register_name("/dev/fb0", major, 0);
if (status != RTEMS_SUCCESSFUL)
{
printk("Error registering frame buffer device!\\n");
printk("Error registering frame buffer device!\n");
rtems_fatal_error_occurred( status );
}
/*
* graphics hardware initialization goes here for non-console
* devices
\*/
*/
return RTEMS_SUCCESSFUL;
}
Opening the Frame Buffer Device
-------------------------------
The ``frame_buffer_open()`` function is called whenever a frame buffer device is opened.
If the frame buffer is registered as "/dev/fb0", the ``frame_buffer_open`` entry point
will be called as the result of an ``open("/dev/fb0", mode)`` in the application.
The ``frame_buffer_open()`` function is called whenever a frame buffer device
is opened. If the frame buffer is registered as :file:`/dev/fb0`, the
``frame_buffer_open`` entry point will be called as the result of an
``open("/dev/fb0", mode)`` in the application.
Thread safety of the frame buffer driver is implementation-dependent.
The VGA driver shown below uses a mutex to prevent multiple open()
operations of the frame buffer device.
Thread safety of the frame buffer driver is implementation-dependent. The VGA
driver shown below uses a mutex to prevent multiple open() operations of the
frame buffer device.
The ``frame_buffer_open()`` function returns RTEMS_SUCCESSFUL when the device driver
is successfully opened, and RTEMS_UNSATISFIED if the device is already open:
.. code:: c
The ``frame_buffer_open()`` function returns ``RTEMS_SUCCESSFUL`` when the
device driver is successfully opened, and ``RTEMS_UNSATISFIED`` if the device
is already open:
.. code-block:: c
rtems_device_driver frame_buffer_close(
rtems_device_major_number major,
rtems_device_minor_number minor,
void \*arg
void *arg
)
{
if (pthread_mutex_unlock(&mutex) == 0) {
/* restore previous state. for VGA this means return to text mode.
* leave out if graphics hardware has been initialized in
* frame_buffer_initialize() \*/
* frame_buffer_initialize()
*/
ega_hwterm();
printk( "FBVGA close called.\\n" );
printk( "FBVGA close called.\n" );
return RTEMS_SUCCESSFUL;
}
return RTEMS_UNSATISFIED;
@ -103,82 +122,92 @@ hardware-specific initialization.
Closing the Frame Buffer Device
-------------------------------
The ``frame_buffer_close()`` is invoked when the frame buffer device
is closed. It frees up any resources allocated in``frame_buffer_open()``, and should restore previous hardware state.
The entry point corresponds to the device driver close entry point.
The ``frame_buffer_close()`` is invoked when the frame buffer device is closed.
It frees up any resources allocated in ``frame_buffer_open()``, and should
restore previous hardware state. The entry point corresponds to the device
driver close entry point.
Returns RTEMS_SUCCESSFUL when the device driver is successfully closed:
.. code:: c
Returns ``RTEMS_SUCCESSFUL`` when the device driver is successfully closed:
.. code-block:: c
rtems_device_driver frame_buffer_close(
rtems_device_major_number major,
rtems_device_minor_number minor,
void \*arg)
void *arg)
{
pthread_mutex_unlock(&mutex);
/* TODO check mutex return value, RTEMS_UNSATISFIED if it failed. we
* don't want to unconditionally call ega_hwterm()... \*/
* don't want to unconditionally call ega_hwterm()... */
/* restore previous state. for VGA this means return to text mode.
* leave out if graphics hardware has been initialized in
* frame_buffer_initialize() \*/
* frame_buffer_initialize() */
ega_hwterm();
printk( "frame buffer close called.\\n" );
printk( "frame buffer close called.\n" );
return RTEMS_SUCCESSFUL;
}
Reading from the Frame Buffer Device
------------------------------------
The ``frame_buffer_read()`` is invoked from a ``read()`` operation
on the frame buffer device.
Read functions should allow normal and partial reading at the end of frame buffer memory.
This method returns RTEMS_SUCCESSFUL when the device is successfully read from:
.. code:: c
The ``frame_buffer_read()`` is invoked from a ``read()`` operation on the frame
buffer device. Read functions should allow normal and partial reading at the
end of frame buffer memory. This method returns ``RTEMS_SUCCESSFUL`` when the
device is successfully read from:
.. code-block:: c
rtems_device_driver frame_buffer_read(
rtems_device_major_number major,
rtems_device_minor_number minor,
void \*arg
void *arg
)
{
rtems_libio_rw_args_t \*rw_args = (rtems_libio_rw_args_t \*)arg;
rw_args->bytes_moved = ((rw_args->offset + rw_args->count) > fb_fix.smem_len ) ? (fb_fix.smem_len - rw_args->offset) : rw_args->count;
memcpy(rw_args->buffer, (const void \*) (fb_fix.smem_start + rw_args->offset), rw_args->bytes_moved);
rtems_libio_rw_args_t *rw_args = (rtems_libio_rw_args_t *)arg;
rw_args->bytes_moved = ((rw_args->offset + rw_args->count) > fb_fix.smem_len ) ?
(fb_fix.smem_len - rw_args->offset) : rw_args->count;
memcpy(rw_args->buffer,
(const void *) (fb_fix.smem_start + rw_args->offset),
rw_args->bytes_moved);
return RTEMS_SUCCESSFUL;
}
Writing to the Frame Buffer Device
----------------------------------
The ``frame_buffer_write()`` is invoked from a ``write()``
operation on the frame buffer device.
The frame buffer write function is similar to the read function, and
should handle similar cases involving partial writes.
The ``frame_buffer_write()`` is invoked from a ``write()`` operation on the
frame buffer device. The frame buffer write function is similar to the read
function, and should handle similar cases involving partial writes.
This method returns RTEMS_SUCCESSFUL when the device is successfully
This method returns ``RTEMS_SUCCESSFUL`` when the device is successfully
written to:
.. code:: c
.. code-block:: c
rtems_device_driver frame_buffer_write(
rtems_device_major_number major,
rtems_device_minor_number minor,
void \*arg
void *arg
)
{
rtems_libio_rw_args_t \*rw_args = (rtems_libio_rw_args_t \*)arg;
rw_args->bytes_moved = ((rw_args->offset + rw_args->count) > fb_fix.smem_len ) ? (fb_fix.smem_len - rw_args->offset) : rw_args->count;
memcpy( (void \*) (fb_fix.smem_start + rw_args->offset), rw_args->buffer, rw_args->bytes_moved);
rtems_libio_rw_args_t *rw_args = (rtems_libio_rw_args_t *)arg;
rw_args->bytes_moved = ((rw_args->offset + rw_args->count) > fb_fix.smem_len ) ?
(fb_fix.smem_len - rw_args->offset) : rw_args->count;
memcpy((void *) (fb_fix.smem_start + rw_args->offset),
rw_args->buffer,
rw_args->bytes_moved);
return RTEMS_SUCCESSFUL;
}
Frame Buffer IO Control
-----------------------
The frame buffer driver allows several ioctls, partially compatible with
the Linux kernel,
to obtain information about the hardware.
The frame buffer driver allows several ioctls, partially compatible with the
Linux kernel, to obtain information about the hardware.
All ``ioctl()`` operations on the frame buffer device invoke``frame_buffer_control()``.
All ``ioctl()`` operations on the frame buffer device invoke
``frame_buffer_control()``.
Ioctls supported:
@ -186,16 +215,18 @@ Ioctls supported:
- ioctl to set and get palette.
.. code:: c
.. code-block:: c
rtems_device_driver frame_buffer_control(
rtems_device_major_number major,
rtems_device_minor_number minor,
void \*arg
void *arg
)
{
rtems_libio_ioctl_args_t \*args = arg;
printk( "FBVGA ioctl called, cmd=%x\\n", args->command );
rtems_libio_ioctl_args_t *args = arg;
printk( "FBVGA ioctl called, cmd=%x\n", args->command );
switch( args->command ) {
case FBIOGET_FSCREENINFO:
args->ioctl_return = get_fix_screen_info( ( struct fb_fix_screeninfo * ) args->buffer );
@ -217,15 +248,9 @@ Ioctls supported:
args->ioctl_return = 0;
break;
}
return RTEMS_SUCCESSFUL;
}
See ``rtems/fb.h`` for more information on the list of ioctls and
data structures they work with.
.. COMMENT: COPYRIGHT (c) 1988-2002.
.. COMMENT: On-Line Applications Research Corporation (OAR).
.. COMMENT: All rights reserved.
See ``rtems/fb.h`` for more information on the list of ioctls and data
structures they work with.

114
bsp_howto/ide_controller.rst
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@ -1,14 +1,17 @@
.. comment SPDX-License-Identifier: CC-BY-SA-4.0
.. COMMENT: COPYRIGHT (c) 1988-2002.
.. COMMENT: On-Line Applications Research Corporation (OAR).
.. COMMENT: All rights reserved.
IDE Controller Driver
#####################
Introduction
============
The IDE Controller driver is responsible for providing an
interface to an IDE Controller. The capabilities provided by this
driver are:
The IDE Controller driver is responsible for providing an interface to an IDE
Controller. The capabilities provided by this driver are:
- Read IDE Controller register
@ -18,35 +21,37 @@ driver are:
- Write data block through IDE Controller Data Register
The reference implementation for an IDE Controller driver can
be found in ``$RTEMS_SRC_ROOT/c/src/libchip/ide``. This driver
is based on the libchip concept and allows to work with any of the IDE
Controller chips simply by appropriate configuration of BSP. Drivers for a
particular IDE Controller chips locate in the following directories: drivers
for well-known IDE Controller chips locate into``$RTEMS_SRC_ROOT/c/src/libchip/ide``, drivers for IDE Controller chips
integrated with CPU locate into``$RTEMS_SRC_ROOT/c/src/lib/libcpu/myCPU`` and
drivers for custom IDE Controller chips (for example, implemented on FPGA)
locate into ``$RTEMS_SRC_ROOT/c/src/lib/libbsp/myBSP``.
There is a README file in these directories for each supported
IDE Controller chip. Each of these README explains how to configure a BSP
for that particular IDE Controller chip.
The reference implementation for an IDE Controller driver can be found in
``$RTEMS_SRC_ROOT/c/src/libchip/ide``. This driver is based on the libchip
concept and allows to work with any of the IDE Controller chips simply by
appropriate configuration of BSP. Drivers for a particular IDE Controller chips
locate in the following directories: drivers for well-known IDE Controller
chips locate into ``$RTEMS_SRC_ROOT/c/src/libchip/ide``, drivers for IDE
Controller chips integrated with CPU locate into
``$RTEMS_SRC_ROOT/c/src/lib/libcpu/myCPU`` and drivers for custom IDE
Controller chips (for example, implemented on FPGA) locate into
``$RTEMS_SRC_ROOT/c/src/lib/libbsp/myBSP``. There is a README file in these
directories for each supported IDE Controller chip. Each of these README
explains how to configure a BSP for that particular IDE Controller chip.
Initialization
==============
IDE Controller chips used by a BSP are statically configured into``IDE_Controller_Table``. The ``ide_controller_initialize`` routine is
IDE Controller chips used by a BSP are statically configured into
``IDE_Controller_Table``. The ``ide_controller_initialize`` routine is
responsible for initialization of all configured IDE controller chips.
Initialization order of the chips based on the order the chips are defined in
the ``IDE_Controller_Table``.
The following actions are performed by the IDE Controller driver
initialization routine:
.. code:: c
The following actions are performed by the IDE Controller driver initialization
routine:
.. code-block:: c
rtems_device_driver ide_controller_initialize(
rtems_device_major_number major,
rtems_device_minor_number minor_arg,
void \*arg
void *arg
)
{
for each IDE Controller chip configured in IDE_Controller_Table
@ -62,13 +67,18 @@ Read IDE Controller Register
The ``ide_controller_read_register`` routine reads the content of the IDE
Controller chip register. IDE Controller chip is selected via the minor
number. This routine is not allowed to be called from an application.
.. code:: c
void ide_controller_read_register(rtems_device_minor_number minor,
unsigned32 reg, unsigned32 \*value)
.. code-block:: c
void ide_controller_read_register(
rtems_device_minor_number minor,
unsigned32 reg,
unsigned32 *value
)
{
get IDE Controller chip configuration information from
IDE_Controller_Table by minor number
invoke read register routine for the chip
}
@ -78,65 +88,69 @@ Write IDE Controller Register
The ``ide_controller_write_register`` routine writes IDE Controller chip
register with specified value. IDE Controller chip is selected via the minor
number. This routine is not allowed to be called from an application.
.. code:: c
void ide_controller_write_register(rtems_device_minor_number minor,
unsigned32 reg, unsigned32 value)
.. code-block:: c
void ide_controller_write_register(
rtems_device_minor_number minor,
unsigned32 reg,
unsigned32 value
)
{
get IDE Controller chip configuration information from
IDE_Controller_Table by minor number
invoke write register routine for the chip
}
Read Data Block Through IDE Controller Data Register
====================================================
The ``ide_controller_read_data_block`` provides multiple consequent read
of the IDE Controller Data Register. IDE Controller chip is selected via the
minor number. The same functionality may be achieved via separate multiple
calls of ``ide_controller_read_register`` routine but``ide_controller_read_data_block`` allows to escape functions call
overhead. This routine is not allowed to be called from an application.
.. code:: c
The ``ide_controller_read_data_block`` provides multiple consequent read of the
IDE Controller Data Register. IDE Controller chip is selected via the minor
number. The same functionality may be achieved via separate multiple calls of
``ide_controller_read_register`` routine but ``ide_controller_read_data_block``
allows to escape functions call overhead. This routine is not allowed to be
called from an application.
.. code-block:: c
void ide_controller_read_data_block(
rtems_device_minor_number minor,
unsigned16 block_size,
blkdev_sg_buffer \*bufs,
uint32_t \*cbuf,
uint32_t \*pos
blkdev_sg_buffer *bufs,
uint32_t *cbuf,
uint32_t *pos
)
{
get IDE Controller chip configuration information from
IDE_Controller_Table by minor number
invoke read data block routine for the chip
}
Write Data Block Through IDE Controller Data Register
=====================================================
The ``ide_controller_write_data_block`` provides multiple consequent write
into the IDE Controller Data Register. IDE Controller chip is selected via the
minor number. The same functionality may be achieved via separate multiple
calls of ``ide_controller_write_register`` routine but``ide_controller_write_data_block`` allows to escape functions call
The ``ide_controller_write_data_block`` provides multiple consequent write into
the IDE Controller Data Register. IDE Controller chip is selected via the minor
number. The same functionality may be achieved via separate multiple calls of
``ide_controller_write_register`` routine but
``ide_controller_write_data_block`` allows to escape functions call
overhead. This routine is not allowed to be called from an application.
.. code:: c
.. code-block:: c
void ide_controller_write_data_block(
rtems_device_minor_number minor,
unsigned16 block_size,
blkdev_sg_buffer \*bufs,
uint32_t \*cbuf,
uint32_t \*pos
blkdev_sg_buffer *bufs,
uint32_t *cbuf,
uint32_t *pos
)
{
get IDE Controller chip configuration information from
IDE_Controller_Table by minor number
invoke write data block routine for the chip
}
.. COMMENT: COPYRIGHT (c) 1988-2002.
.. COMMENT: On-Line Applications Research Corporation (OAR).
.. COMMENT: All rights reserved.

53
bsp_howto/index.rst
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@ -4,41 +4,41 @@
BSP and Device Driver Development Guide
=======================================
COPYRIGHT (c) 1988 - 2015.
BSP and Device Driver Development Guide
---------------------------------------
On-Line Applications Research Corporation (OAR).
| COPYRIGHT (c) 1988 - 2015.
| On-Line Applications Research Corporation (OAR).
The authors have used their best efforts in preparing
this material. These efforts include the development, research,
and testing of the theories and programs to determine their
effectiveness. No warranty of any kind, expressed or implied,
with regard to the software or the material contained in this
document is provided. No liability arising out of the
application or use of any product described in this document is
assumed. The authors reserve the right to revise this material
and to make changes from time to time in the content hereof
without obligation to notify anyone of such revision or changes.
The authors have used their best efforts in preparing this material. These
efforts include the development, research, and testing of the theories and
programs to determine their effectiveness. No warranty of any kind, expressed
or implied, with regard to the software or the material contained in this
document is provided. No liability arising out of the application or use of
any product described in this document is assumed. The authors reserve the
right to revise this material and to make changes from time to time in the
content hereof without obligation to notify anyone of such revision or changes.
The RTEMS Project is hosted at http://www.rtems.org. Any
inquiries concerning RTEMS, its related support components, or its
documentation should be directed to the Community Project hosted athttp://www.rtems.org.
The RTEMS Project is hosted at http://www.rtems.org. Any inquiries concerning
RTEMS, its related support components, or its documentation should be directed
to the Community Project hosted at http://www.rtems.org.
Any inquiries for commercial services including training, support, custom
development, application development assistance should be directed tohttp://www.rtems.com.
Table of Contents
-----------------
.. toctree::
preface
.. topic:: RTEMS Online Resources
================ =============================
Home https://www.rtems.org/
Developers https://devel.rtems.org/
Documentation https://docs.rtems.org/
Bug Reporting https://devel.rtems.org/query
Mailing Lists https://lists.rtems.org/
Git Repositories https://git.rtems.org/
================ =============================
.. toctree::
:maxdepth: 3
:numbered:
preface
target_dependant_files
makefiles
linker_script
@ -59,8 +59,5 @@ Table of Contents
discrete
command
* :ref:`genindex`
* :ref:`search`

427
bsp_howto/initilization_code.rst
View File

@ -1,5 +1,9 @@
.. comment SPDX-License-Identifier: CC-BY-SA-4.0
.. COMMENT: COPYRIGHT (c) 1988-2008.
.. COMMENT: On-Line Applications Research Corporation (OAR).
.. COMMENT: All rights reserved.
Initialization Code
###################
@ -7,87 +11,85 @@ Introduction
============
The initialization code is the first piece of code executed when there's a
reset/reboot. Its purpose is to initialize the board for the application.
This chapter contains a narrative description of the initialization
process followed by a description of each of the files and routines
commonly found in the BSP related to initialization. The remainder of
this chapter covers special issues which require attention such
as interrupt vector table and chip select initialization.
reset/reboot. Its purpose is to initialize the board for the application. This
chapter contains a narrative description of the initialization process followed
by a description of each of the files and routines commonly found in the BSP
related to initialization. The remainder of this chapter covers special issues
which require attention such as interrupt vector table and chip select
initialization.
Most of the examples in this chapter will be based on the SPARC/ERC32 and
m68k/gen68340 BSP initialization code. Like most BSPs, the initialization
for these BSP is divided into two subdirectories under the BSP source
directory. The BSP source code for these BSPs is in the following
directories:
m68k/gen68340 BSP initialization code. Like most BSPs, the initialization for
these BSP is divided into two subdirectories under the BSP source directory.
The BSP source code for these BSPs is in the following directories:
.. code:: c
c/src/lib/libbsp/m68k/gen68340
c/src/lib/libbsp/sparc/erc32
Both BSPs contain startup code written in assembly language and C.
The gen68340 BSP has its early initialization start code in the``start340`` subdirectory and its C startup code in the ``startup``
directory. In the ``start340`` directory are two source files.
The file ``startfor340only.s`` is the simpler of these files as it only
has initialization code for a MC68340 board. The file ``start340.s``
contains initialization for a 68349 based board as well.
Both BSPs contain startup code written in assembly language and C. The
gen68340 BSP has its early initialization start code in the ``start340``
subdirectory and its C startup code in the ``startup`` directory. In the
``start340`` directory are two source files. The file ``startfor340only.s`` is
the simpler of these files as it only has initialization code for a MC68340
board. The file ``start340.s`` contains initialization for a 68349 based board
as well.
Similarly, the ERC32 BSP has startup code written in assembly language and C.
However, this BSP shares this code with other SPARC BSPs. Thus the
``Makefile.am`` explicitly references the following files for this
functionality.
Similarly, the ERC32 BSP has startup code written in assembly language
and C. However, this BSP shares this code with other SPARC BSPs.
Thus the ``Makefile.am`` explicitly references the following files
for this functionality.
.. code:: c
../../sparc/shared/start.S
*NOTE:* In most BSPs, the directory named ``start340`` in the
gen68340 BSP would be simply named ``start`` or start followed by a
BSP designation.
.. note::
In most BSPs, the directory named ``start340`` in the gen68340 BSP would be
simply named ``start`` or start followed by a BSP designation.
Required Global Variables
=========================
Although not strictly part of initialization, there are a few global
variables assumed to exist by reusable device drivers. These global
variables should only defined by the BSP when using one of these device
drivers.
Although not strictly part of initialization, there are a few global variables
assumed to exist by reusable device drivers. These global variables should
only defined by the BSP when using one of these device drivers.
The BSP author probably should be aware of the ``Configuration``
Table structure generated by ``<rtems/confdefs.h>`` during debug but
should not explicitly reference it in the source code. There are helper
routines provided by RTEMS to access individual fields.
The BSP author probably should be aware of the ``Configuration`` Table
structure generated by ``<rtems/confdefs.h>`` during debug but should not
explicitly reference it in the source code. There are helper routines provided
by RTEMS to access individual fields.
In older RTEMS versions, the BSP included a number of required global
variables. We have made every attempt to eliminate these in the interest
of simplicity.
variables. We have made every attempt to eliminate these in the interest of
simplicity.
Board Initialization
====================
This section describes the steps an application goes through from the
time the first BSP code is executed until the first application task
executes. The following figure illustrates the program flow during
this sequence:
This section describes the steps an application goes through from the time the
first BSP code is executed until the first application task executes.
IMAGE NOT AVAILABLE IN ASCII VERSION
The initialization flows from assembly language start code to the shared
``bootcard.c`` framework then through the C Library, RTEMS, device driver
initialization phases, and the context switch to the first application task.
After this, the application executes until it calls ``exit``,
``rtems_shutdown_executive``, or some other normal termination initiating
routine and a fatal system state is reached. The optional
``bsp_fatal_extension`` initial extension can perform BSP specific system
termination.
The above figure illustrates the flow from assembly language start code
to the shared ``bootcard.c`` framework then through the C Library,
RTEMS, device driver initialization phases, and the context switch
to the first application task. After this, the application executes
until it calls ``exit``, ``rtems_shutdown_executive``, or some
other normal termination initiating routine and a fatal system state is
reached. The optional ``bsp_fatal_extension`` initial extension can perform
BSP specific system termination.
The routines invoked during this will be discussed and their location
in the RTEMS source tree pointed out as we discuss each.
The routines invoked during this will be discussed and their location in the
RTEMS source tree pointed out as we discuss each.
Start Code - Assembly Language Initialization
---------------------------------------------
The assembly language code in the directory ``start`` is the first part
of the application to execute. It is responsible for initializing the
processor and board enough to execute the rest of the BSP. This includes:
The assembly language code in the directory ``start`` is the first part of the
application to execute. It is responsible for initializing the processor and
board enough to execute the rest of the BSP. This includes:
- initializing the stack
@ -97,29 +99,29 @@ processor and board enough to execute the rest of the BSP. This includes:
- copy the initialized data from ROM to RAM
The general rule of thumb is that the start code in assembly should
do the minimum necessary to allow C code to execute to complete the
initialization sequence.
The general rule of thumb is that the start code in assembly should do the
minimum necessary to allow C code to execute to complete the initialization
sequence.
The initial assembly language start code completes its execution by
invoking the shared routine ``boot_card()``.
The initial assembly language start code completes its execution by invoking
the shared routine ``boot_card()``.
The label (symbolic name) associated with the starting address of the
program is typically called ``start``. The start object file is the
first object file linked into the program image so it is ensured that
the start code is at offset 0 in the ``.text`` section. It is the
responsibility of the linker script in conjunction with the compiler
specifications file to put the start code in the correct location in
the application image.
The label (symbolic name) associated with the starting address of the program
is typically called ``start``. The start object file is the first object file
linked into the program image so it is ensured that the start code is at offset
0 in the ``.text`` section. It is the responsibility of the linker script in
conjunction with the compiler specifications file to put the start code in the
correct location in the application image.
boot_card() - Boot the Card
---------------------------
The ``boot_card()`` is the first C code invoked. This file is the
core component in the RTEMS BSP Initialization Framework and provides
the proper sequencing of initialization steps for the BSP, RTEMS and
device drivers. All BSPs use the same shared version of ``boot_card()``
which is located in the following file:
The ``boot_card()`` is the first C code invoked. This file is the core
component in the RTEMS BSP Initialization Framework and provides the proper
sequencing of initialization steps for the BSP, RTEMS and device drivers. All
BSPs use the same shared version of ``boot_card()`` which is located in the
following file:
.. code:: c
c/src/lib/libbsp/shared/bootcard.c
@ -131,33 +133,38 @@ The ``boot_card()`` routine performs the following functions:
- It sets the command line argument variables
for later use by the application.
- It invokes the BSP specific routine ``bsp_work_area_initialize()``
which is supposed to initialize the RTEMS Workspace and the C Program Heap.
Usually the default implementation in``c/src/lib/libbsp/shared/bspgetworkarea.c`` should be sufficient. Custom
implementations can use ``bsp_work_area_initialize_default()`` or``bsp_work_area_initialize_with_table()`` available as inline functions from``#include <bsp/bootcard.h>``.
- It invokes the BSP specific routine ``bsp_work_area_initialize()`` which is
supposed to initialize the RTEMS Workspace and the C Program Heap. Usually
the default implementation in ``c/src/lib/libbsp/shared/bspgetworkarea.c``
should be sufficient. Custom implementations can use
``bsp_work_area_initialize_default()`` or
``bsp_work_area_initialize_with_table()`` available as inline functions
from``#include <bsp/bootcard.h>``.
- It invokes the BSP specific routine ``bsp_start()`` which is
written in C and thus able to perform more advanced initialization.
Often MMU, bus and interrupt controller initialization occurs here. Since the
RTEMS Workspace and the C Program Heap was already initialized by``bsp_work_area_initialize()``, this routine may use ``malloc()``, etc.
- It invokes the BSP specific routine ``bsp_start()`` which is written in C and
thus able to perform more advanced initialization. Often MMU, bus and
interrupt controller initialization occurs here. Since the RTEMS Workspace
and the C Program Heap was already initialized by
``bsp_work_area_initialize()``, this routine may use ``malloc()``, etc.
- It invokes the RTEMS directive``rtems_initialize_data_structures()`` to initialize the RTEMS
executive to a state where objects can be created but tasking is not
enabled.
- It invokes the RTEMS directive ``rtems_initialize_data_structures()`` to
initialize the RTEMS executive to a state where objects can be created but
tasking is not enabled.
- It invokes the BSP specific routine ``bsp_libc_init()`` to initialize
the C Library. Usually the default implementation in``c/src/lib/libbsp/shared/bsplibc.c`` should be sufficient.
- It invokes the BSP specific routine ``bsp_libc_init()`` to initialize the C
Library. Usually the default implementation in
``c/src/lib/libbsp/shared/bsplibc.c`` should be sufficient.
- It invokes the RTEMS directive``rtems_initialize_before_drivers()`` to initialize the MPCI Server
thread in a multiprocessor configuration and execute API specific
extensions.
- It invokes the RTEMS directive ``rtems_initialize_before_drivers()`` to
initialize the MPCI Server thread in a multiprocessor configuration and
execute API specific extensions.
- It invokes the BSP specific routine ``bsp_predriver_hook``. For
most BSPs, the implementation of this routine does nothing.
- It invokes the BSP specific routine ``bsp_predriver_hook``. For most BSPs,
the implementation of this routine does nothing.
- It invokes the RTEMS directive``rtems_initialize_device_drivers()`` to initialize the statically
configured set of device drivers in the order they were specified in
the Configuration Table.
- It invokes the RTEMS directive ``rtems_initialize_device_drivers()`` to
initialize the statically configured set of device drivers in the order they
were specified in the Configuration Table.
- It invokes the BSP specific routine ``bsp_postdriver_hook``. For
most BSPs, the implementation of this routine does nothing. However, some
@ -166,19 +173,19 @@ The ``boot_card()`` routine performs the following functions:
for the BSP to insert BSP specific code into the initialization sequence.
- It invokes the RTEMS directive ``rtems_initialize_start_multitasking()``
which initiates multitasking and performs a context switch to the
first user application task and may enable interrupts as a side-effect of
that context switch. The context switch saves the executing context. The
application runs now. The directive rtems_shutdown_executive() will return
to the saved context. The exit() function will use this directive.
After a return to the saved context a fatal system state is reached. The
fatal source is RTEMS_FATAL_SOURCE_EXIT with a fatal code set to the value
passed to rtems_shutdown_executive().
The enabling of interrupts during the first context switch is often the source
for fatal errors during BSP development because the BSP did not clear and/or
disable all interrupt sources and a spurious interrupt will occur.
When in the context of the first task but before its body has been
entered, any C++ Global Constructors will be invoked.
which initiates multitasking and performs a context switch to the first user
application task and may enable interrupts as a side-effect of that context
switch. The context switch saves the executing context. The application
runs now. The directive ``rtems_shutdown_executive()`` will return to the
saved context. The ``exit()`` function will use this directive. After a
return to the saved context a fatal system state is reached. The fatal
source is ``RTEMS_FATAL_SOURCE_EXIT`` with a fatal code set to the value
passed to rtems_shutdown_executive(). The enabling of interrupts during the
first context switch is often the source for fatal errors during BSP
development because the BSP did not clear and/or disable all interrupt
sources and a spurious interrupt will occur. When in the context of the
first task but before its body has been entered, any C++ Global Constructors
will be invoked.
That's it. We just went through the entire sequence.
@ -189,15 +196,18 @@ This is the first BSP specific C routine to execute during system
initialization. It must initialize the support for allocating memory from the
C Program Heap and RTEMS Workspace commonly referred to as the work areas.
Many BSPs place the work areas at the end of RAM although this is certainly not
a requirement. Usually the default implementation in:file:`c/src/lib/libbsp/shared/bspgetworkarea.c` should be sufficient. Custom
implementations can use ``bsp_work_area_initialize_default()`` or``bsp_work_area_initialize_with_table()`` available as inline functions from``#include <bsp/bootcard.h>``.
a requirement. Usually the default implementation
in:file:`c/src/lib/libbsp/shared/bspgetworkarea.c` should be sufficient.
Custom implementations can use ``bsp_work_area_initialize_default()``
or``bsp_work_area_initialize_with_table()`` available as inline functions from
``#include <bsp/bootcard.h>``.
bsp_start() - BSP Specific Initialization
-----------------------------------------
This is the second BSP specific C routine to execute during system
initialization. It is called right after ``bsp_work_area_initialize()``.
The ``bsp_start()`` routine often performs required fundamental hardware
initialization. It is called right after ``bsp_work_area_initialize()``. The
``bsp_start()`` routine often performs required fundamental hardware
initialization such as setting bus controller registers that do not have a
direct impact on whether or not C code can execute. The interrupt controllers
are usually initialized here. The source code for this routine is usually
@ -206,52 +216,56 @@ It is not allowed to create any operating system objects, e.g. RTEMS
semaphores.
After completing execution, this routine returns to the ``boot_card()``
routine. In case of errors, the initialization should be terminated via``bsp_fatal()``.
routine. In case of errors, the initialization should be terminated via
``bsp_fatal()``.
bsp_predriver_hook() - BSP Specific Predriver Hook
--------------------------------------------------
The ``bsp_predriver_hook()`` method is the BSP specific routine that is
invoked immediately before the the device drivers are initialized. RTEMS
initialization is complete but interrupts and tasking are disabled.
The ``bsp_predriver_hook()`` method is the BSP specific routine that is invoked
immediately before the the device drivers are initialized. RTEMS initialization
is complete but interrupts and tasking are disabled.
The BSP may use the shared version of this routine which is empty.
Most BSPs do not provide a specific implementation of this callback.
The BSP may use the shared version of this routine which is empty. Most BSPs
do not provide a specific implementation of this callback.
Device Driver Initialization
----------------------------
At this point in the initialization sequence, the initialization
routines for all of the device drivers specified in the Device
Driver Table are invoked. The initialization routines are invoked
in the order they appear in the Device Driver Table.
At this point in the initialization sequence, the initialization routines for
all of the device drivers specified in the Device Driver Table are invoked.
The initialization routines are invoked in the order they appear in the Device
Driver Table.
The Driver Address Table is part of the RTEMS Configuration Table. It
defines device drivers entry points (initialization, open, close, read,
write, and control). For more information about this table, please
refer to the *Configuring a System* chapter in the*RTEMS Application C User's Guide*.
The Driver Address Table is part of the RTEMS Configuration Table. It defines
device drivers entry points (initialization, open, close, read, write, and
control). For more information about this table, please refer to the
*Configuring a System* chapter in the *RTEMS Application C User's Guide*.
The RTEMS initialization procedure calls the initialization function for
every driver defined in the RTEMS Configuration Table (this allows
one to include only the drivers needed by the application).
The RTEMS initialization procedure calls the initialization function for every
driver defined in the RTEMS Configuration Table (this allows one to include
only the drivers needed by the application).
All these primitives have a major and a minor number as arguments:
- the major number refers to the driver type,
- the minor number is used to control two peripherals with the same
driver (for instance, we define only one major number for the serial
driver, but two minor numbers for channel A and B if there are two
channels in the UART).
- the minor number is used to control two peripherals with the same driver (for
instance, we define only one major number for the serial driver, but two
minor numbers for channel A and B if there are two channels in the UART).
RTEMS Postdriver Callback
-------------------------
The ``bsp_postdriver_hook()`` BSP specific routine is invoked
immediately after the the device drivers and MPCI are initialized.
Interrupts and tasking are disabled.
The ``bsp_postdriver_hook()`` BSP specific routine is invoked immediately after
the the device drivers and MPCI are initialized. Interrupts and tasking are
disabled.
Most BSPs use the shared implementation of this routine which is responsible
for opening the device ``/dev/console`` for standard input, output and error if
the application has configured the Console Device Driver. This file is located
at:
Most BSPs use the shared implementation of this routine which is responsible for opening the device ``/dev/console`` for standard input, output and error if the application has configured the Console Device Driver. This file is located at:
.. code:: c
c/src/lib/libbsp/shared/bsppost.c
@ -259,121 +273,110 @@ Most BSPs use the shared implementation of this routine which is responsible for
The Interrupt Vector Table
==========================
The Interrupt Vector Table is called different things on different
processor families but the basic functionality is the same. Each
entry in the Table corresponds to the handler routine for a particular
interrupt source. When an interrupt from that source occurs, the
specified handler routine is invoked. Some context information is
saved by the processor automatically when this happens. RTEMS saves
enough context information so that an interrupt service routine
can be implemented in a high level language.
The Interrupt Vector Table is called different things on different processor
families but the basic functionality is the same. Each entry in the Table
corresponds to the handler routine for a particular interrupt source. When an
interrupt from that source occurs, the specified handler routine is invoked.
Some context information is saved by the processor automatically when this
happens. RTEMS saves enough context information so that an interrupt service
routine can be implemented in a high level language.
On some processors, the Interrupt Vector Table is at a fixed address. If
this address is in RAM, then usually the BSP only has to initialize
it to contain pointers to default handlers. If the table is in ROM,
then the application developer will have to take special steps to
fill in the table.
On some processors, the Interrupt Vector Table is at a fixed address. If this
address is in RAM, then usually the BSP only has to initialize it to contain
pointers to default handlers. If the table is in ROM, then the application
developer will have to take special steps to fill in the table.
If the base address of the Interrupt Vector Table can be dynamically
changed to an arbitrary address, then the RTEMS port to that processor
family will usually allocate its own table and install it. For example,
on some members of the Motorola MC68xxx family, the Vector Base Register
(``vbr``) contains this base address.
If the base address of the Interrupt Vector Table can be dynamically changed to
an arbitrary address, then the RTEMS port to that processor family will usually
allocate its own table and install it. For example, on some members of the
Motorola MC68xxx family, the Vector Base Register (``vbr``) contains this base
address.
Interrupt Vector Table on the gen68340 BSP
------------------------------------------
The gen68340 BSP provides a default Interrupt Vector Table in the
file ``$BSP_ROOT/start340/start340.s``. After the ``entry``
label is the definition of space reserved for the table of
interrupts vectors. This space is assigned the symbolic name
of ``__uhoh`` in the ``gen68340`` BSP.
The gen68340 BSP provides a default Interrupt Vector Table in the file
``$BSP_ROOT/start340/start340.s``. After the ``entry`` label is the definition
of space reserved for the table of interrupts vectors. This space is assigned
the symbolic name of ``__uhoh`` in the ``gen68340`` BSP.
At ``__uhoh`` label is the default interrupt handler routine. This
routine is only called when an unexpected interrupts is raised. One can
add their own routine there (in that case there's a call to a routine -
$BSP_ROOT/startup/dumpanic.c - that prints which address caused the
interrupt and the contents of the registers, stack, etc.), but this should
not return.
At ``__uhoh`` label is the default interrupt handler routine. This routine is
only called when an unexpected interrupts is raised. One can add their own
routine there (in that case there's a call to a routine -
$BSP_ROOT/startup/dumpanic.c - that prints which address caused the interrupt
and the contents of the registers, stack, etc.), but this should not return.
Chip Select Initialization
==========================
When the microprocessor accesses a memory area, address decoding is
handled by an address decoder, so that the microprocessor knows which
memory chip(s) to access. The following figure illustrates this:
When the microprocessor accesses a memory area, address decoding is handled by
an address decoder, so that the microprocessor knows which memory chip(s) to
access. The following figure illustrates this:
.. code:: c
.. code::
+-------------------+
------------| |
------------| \|------------
------------| Address \|------------
------------| Decoder \|------------
------------| \|------------
------------| |------------
------------| Address |------------
------------| Decoder |------------
------------| |------------
------------| |
+-------------------+
CPU Bus Chip Select
The Chip Select registers must be programmed such that they match
the ``linkcmds`` settings. In the gen68340 BSP, ROM and RAM
addresses can be found in both the ``linkcmds`` and initialization
code, but this is not a great way to do this. It is better to
define addresses in the linker script.
The Chip Select registers must be programmed such that they match the
``linkcmds`` settings. In the gen68340 BSP, ROM and RAM addresses can be found
in both the ``linkcmds`` and initialization code, but this is not a great way
to do this. It is better to define addresses in the linker script.
Integrated Processor Registers Initialization
=============================================
The CPUs used in many embedded systems are highly complex devices
with multiple peripherals on the CPU itself. For these devices,
there are always some specific integrated processor registers
that must be initialized. Refer to the processors' manuals for
details on these registers and be VERY careful programming them.
The CPUs used in many embedded systems are highly complex devices with multiple
peripherals on the CPU itself. For these devices, there are always some
specific integrated processor registers that must be initialized. Refer to the
processors' manuals for details on these registers and be VERY careful
programming them.
Data Section Recopy
===================
The next initialization part can be found in``$BSP340_ROOT/start340/init68340.c``. First the Interrupt
Vector Table is copied into RAM, then the data section recopy is initiated
(_CopyDataClearBSSAndStart in ``$BSP340_ROOT/start340/startfor340only.s``).
The next initialization part can be found in
``$BSP340_ROOT/start340/init68340.c``. First the Interrupt Vector Table is
copied into RAM, then the data section recopy is initiated
(``_CopyDataClearBSSAndStart`` in ``$BSP340_ROOT/start340/startfor340only.s``).
This code performs the following actions:
- copies the .data section from ROM to its location reserved in RAM
(see `Initialized Data`_ for more details about this copy),
- copies the .data section from ROM to its location reserved in RAM (see
`Initialized Data`_ for more details about this copy),
- clear ``.bss`` section (all the non-initialized
data will take value 0).
- clear ``.bss`` section (all the non-initialized data will take value 0).
The RTEMS Configuration Table
=============================
The RTEMS configuration table contains the maximum number of objects RTEMS
can handle during the application (e.g. maximum number of tasks,
semaphores, etc.). It's used to allocate the size for the RTEMS inner data
structures.
The RTEMS configuration table contains the maximum number of objects RTEMS can
handle during the application (e.g. maximum number of tasks, semaphores,
etc.). It's used to allocate the size for the RTEMS inner data structures.
The RTEMS configuration table is application dependent, which means that
one has to provide one per application. It is usually defined by defining
macros and including the header file ``<rtems/confdefs.h>``. In simple
applications such as the tests provided with RTEMS, it is commonly found
in the main module of the application. For more complex applications,
it may be in a file by itself.
The RTEMS configuration table is application dependent, which means that one
has to provide one per application. It is usually defined by defining macros
and including the header file ``<rtems/confdefs.h>``. In simple applications
such as the tests provided with RTEMS, it is commonly found in the main module
of the application. For more complex applications, it may be in a file by
itself.
The header file ``<rtems/confdefs.h>`` defines a constant table
named ``Configuration``. With RTEMS 4.8 and older, it was accepted
practice for the BSP to copy this table into a modifiable copy named``BSP_Configuration``. This copy of the table was modified to define
the base address of the RTEMS Executive Workspace as well as to reflect
any BSP and device driver requirements not automatically handled by the
application. In 4.9 and newer, we have eliminated the BSP copies of the
configuration tables and are making efforts to make the configuration
information generated by ``<rtems/confdefs.h>`` constant and read only.
For more information on the RTEMS Configuration Table, refer to the*RTEMS Application C User's Guide*.
.. COMMENT: COPYRIGHT (c) 1988-2008.
.. COMMENT: On-Line Applications Research Corporation (OAR).
.. COMMENT: All rights reserved.
The header file ``<rtems/confdefs.h>`` defines a constant table named
``Configuration``. With RTEMS 4.8 and older, it was accepted practice for the
BSP to copy this table into a modifiable copy named ``BSP_Configuration``.
This copy of the table was modified to define the base address of the RTEMS
Executive Workspace as well as to reflect any BSP and device driver
requirements not automatically handled by the application. In 4.9 and newer,
we have eliminated the BSP copies of the configuration tables and are making
efforts to make the configuration information generated by
``<rtems/confdefs.h>`` constant and read only.
For more information on the RTEMS Configuration Table, refer to the *RTEMS
Application C User's Guide*.

295
bsp_howto/linker_script.rst
View File

@ -1,5 +1,10 @@
.. comment SPDX-License-Identifier: CC-BY-SA-4.0
.. COMMENT: COPYRIGHT (c) 1988-2011.
.. COMMENT: On-Line Applications Research Corporation (OAR).
.. COMMENT: All rights reserved.
Linker Script
#############
@ -7,27 +12,25 @@ What is a "linkcmds" file?
==========================
The ``linkcmds`` file is a script which is passed to the linker at linking
time. This file describes the memory configuration of the board as needed
to link the program. Specifically it specifies where the code and data
for the application will reside in memory.
time. This file describes the memory configuration of the board as needed to
link the program. Specifically it specifies where the code and data for the
application will reside in memory.
The format of the linker script is defined by the GNU Loader ``ld``
which is included as a component of the GNU Binary Utilities. If you
are using GNU/Linux, then you probably have the documentation installed
already and are using these same tools configured for *native* use.
Please visit the Binutils project http://sourceware.org/binutils/
if you need more information.
The format of the linker script is defined by the GNU Loader ``ld`` which is
included as a component of the GNU Binary Utilities. If you are using
GNU/Linux, then you probably have the documentation installed already and are
using these same tools configured for *native* use. Please visit the Binutils
project http://sourceware.org/binutils/ if you need more information.
Program Sections
================
An embedded systems programmer must be much more aware of the
placement of their executable image in memory than the average
applications programmer. A program destined to be embedded as well
as the target system have some specific properties that must be
taken into account. Embedded machines often mean average performances
and small memory usage. It is the memory usage that concerns us
when examining the linker command file.
An embedded systems programmer must be much more aware of the placement of
their executable image in memory than the average applications programmer. A
program destined to be embedded as well as the target system have some specific
properties that must be taken into account. Embedded machines often mean
average performances and small memory usage. It is the memory usage that
concerns us when examining the linker command file.
Two types of memories have to be distinguished:
@ -35,90 +38,88 @@ Two types of memories have to be distinguished:
- ROM - non-volatile but read only
Even though RAM and ROM can be found in every personal computer,
one generally doesn't care about them. In a personal computer,
a program is nearly always stored on disk and executed in RAM. Things
are a bit different for embedded targets: the target will execute the
program each time it is rebooted or switched on. The application
program is stored in non-volatile memory such as ROM, PROM, EEPROM,
or Flash. On the other hand, data processing occurs in RAM.
Even though RAM and ROM can be found in every personal computer, one generally
doesn't care about them. In a personal computer, a program is nearly always
stored on disk and executed in RAM. Things are a bit different for embedded
targets: the target will execute the program each time it is rebooted or
switched on. The application program is stored in non-volatile memory such as
ROM, PROM, EEPROM, or Flash. On the other hand, data processing occurs in RAM.
This leads us to the structure of an embedded program. In rough terms,
an embedded program is made of sections. It is the responsibility of
the application programmer to place these sections in the appropriate
place in target memory. To make this clearer, if using the COFF
object file format on the Motorola m68k family of microprocessors,
the following sections will be present:
This leads us to the structure of an embedded program. In rough terms, an
embedded program is made of sections. It is the responsibility of the
application programmer to place these sections in the appropriate place in
target memory. To make this clearer, if using the COFF object file format on
the Motorola m68k family of microprocessors, the following sections will be
present:
- *code (``.text``) section*:
is the program's code and it should not be modified.
This section may be placed in ROM.
- code (``.text``) section:
is the program's code and it should not be modified. This section may be
placed in ROM.
- *non-initialized data (``.bss``) section*:
- non-initialized data (``.bss``) section:
holds uninitialized variables of the program. It can stay in RAM.
- *initialized data (``.data``) section*:
holds the initialized program data which may be modified during the
program's life. This means they have to be in RAM.
On the other hand, these variables must be set to predefined values, and
those predefined values have to be stored in ROM.
- initialized data (``.data``) section:
holds the initialized program data which may be modified during the program's
life. This means they have to be in RAM. On the other hand, these variables
must be set to predefined values, and those predefined values have to be
stored in ROM.
*NOTE:* Many programs and support libraries unknowingly assume that the``.bss`` section and, possibly, the application heap are initialized
to zero at program start. This is not required by the ISO/ANSI C Standard
but is such a common requirement that most BSPs do this.
.. note::
That brings us up to the notion of the image of an executable: it consists
of the set of the sections that together constitute the application.
Many programs and support libraries unknowingly assume that the ``.bss``
section and, possibly, the application heap are initialized to zero at
program start. This is not required by the ISO/ANSI C Standard but is such
a common requirement that most BSPs do this.
That brings us up to the notion of the image of an executable: it consists of
the set of the sections that together constitute the application.
Image of an Executable
======================
As a program executable has many sections (note that the user can define
their own, and that compilers define theirs without any notice), one has to
specify the placement of each section as well as the type of memory
(RAM or ROM) the sections will be placed into.
For instance, a program compiled for a Personal Computer will see all the
sections to go to RAM, while a program destined to be embedded will see
some of his sections going into the ROM.
As a program executable has many sections (note that the user can define their
own, and that compilers define theirs without any notice), one has to specify
the placement of each section as well as the type of memory (RAM or ROM) the
sections will be placed into. For instance, a program compiled for a Personal
Computer will see all the sections to go to RAM, while a program destined to be
embedded will see some of his sections going into the ROM.
The connection between a section and where that section is loaded into
memory is made at link time. One has to let the linker know where
the different sections are to be placed once they are in memory.
The connection between a section and where that section is loaded into memory
is made at link time. One has to let the linker know where the different
sections are to be placed once they are in memory.
The following example shows a simple layout of program sections. With
some object formats, there are many more sections but the basic
layout is conceptually similar.
.. code:: c
The following example shows a simple layout of program sections. With some
object formats, there are many more sections but the basic layout is
conceptually similar.
+-----------------+-------------+
| .text | RAM or ROM |
+-----------------+-------------+
| .data | RAM |
+-----------------+-------------+
| .bss | RAM |
+-----------------+-------------+
============ =============
.text RAM or ROM
.data RAM
.bss RAM
============ =============
Example Linker Command Script
=============================
The GNU linker has a command language to specify the image format. This
command language can be quite complicated but most of what is required
can be learned by careful examination of a well-documented example.
The following is a heavily commented version of the linker script
used with the the ``gen68340`` BSP This file can be found at
$BSP340_ROOT/startup/linkcmds.
command language can be quite complicated but most of what is required can be
learned by careful examination of a well-documented example. The following is
a heavily commented version of the linker script used with the the ``gen68340``
BSP This file can be found at $BSP340_ROOT/startup/linkcmds.
.. code:: c
/*
* Specify that the output is to be coff-m68k regardless of what the
* native object format is.
\*/
*/
OUTPUT_FORMAT(coff-m68k)
/*
* Set the amount of RAM on the target board.
*
* NOTE: The default may be overridden by passing an argument to ld.
\*/
*/
RamSize = DEFINED(RamSize) ? RamSize : 4M;
/*
* Set the amount of RAM to be used for the application heap. Objects
@ -134,7 +135,7 @@ $BSP340_ROOT/startup/linkcmds.
*
* NOTE 3: The GNAT/RTEMS run-time requires additional memory in
* the Heap.
\*/
*/
HeapSize = DEFINED(HeapSize) ? HeapSize : 0x10000;
/*
* Set the size of the starting stack used during BSP initialization
@ -142,7 +143,7 @@ $BSP340_ROOT/startup/linkcmds.
* by RTEMS are used.
*
* NOTE: The default may be overridden by passing an argument to ld.
\*/
*/
StackSize = DEFINED(StackSize) ? StackSize : 0x1000;
/*
* Starting addresses and length of RAM and ROM.
@ -150,7 +151,7 @@ $BSP340_ROOT/startup/linkcmds.
* The addresses must be valid addresses on the board. The
* Chip Selects should be initialized such that the code addresses
* are valid.
\*/
*/
MEMORY {
ram : ORIGIN = 0x10000000, LENGTH = 4M
rom : ORIGIN = 0x01000000, LENGTH = 4M
@ -158,7 +159,7 @@ $BSP340_ROOT/startup/linkcmds.
/*
* This is for the network driver. See the Networking documentation
* for more details.
\*/
*/
ETHERNET_ADDRESS =
DEFINED(ETHERNET_ADDRESS) ? ETHERNET_ADDRESS : 0xDEAD12;
/*
@ -170,73 +171,73 @@ $BSP340_ROOT/startup/linkcmds.
* ensure that the variable is accessible from C code with a
* single underscore. Some object formats automatically add
* a leading underscore to all C global symbols.
\*/
*/
SECTIONS {
/*
* Make the RomBase variable available to the application.
\*/
*/
_RamSize = RamSize;
__RamSize = RamSize;
/*
* Boot PROM - Set the RomBase variable to the start of the ROM.
\*/
*/
rom : {
_RomBase = .;
__RomBase = .;
} >rom
/*
* Dynamic RAM - set the RamBase variable to the start of the RAM.
\*/
*/
ram : {
_RamBase = .;
__RamBase = .;
} >ram
/*
* Text (code) goes into ROM
\*/
*/
.text : {
/*
* Create a symbol for each object (.o).
\*/
*/
CREATE_OBJECT_SYMBOLS
/*
* Put all the object files code sections here.
\*/
\*(.text)
. = ALIGN (16); /* go to a 16-byte boundary \*/
*/
*(.text)
. = ALIGN (16); /* go to a 16-byte boundary */
/*
* C++ constructors and destructors
*
* NOTE: See the CROSSGCC mailing-list FAQ for
* more details about the "\[......]".
\*/
*/
__CTOR_LIST__ = .;
\[......]
[......]
__DTOR_END__ = .;
/*
* Declares where the .text section ends.
\*/
*/
etext = .;
_etext = .;
} >rom
/*
* Exception Handler Frame section
\*/
*/
.eh_fram : {
. = ALIGN (16);
\*(.eh_fram)
*(.eh_fram)
} >ram
/*
* GCC Exception section
\*/
*/
.gcc_exc : {
. = ALIGN (16);
\*(.gcc_exc)
*(.gcc_exc)
} >ram
/*
* Special variable to let application get to the dual-ported
* memory.
\*/
*/
dpram : {
m340 = .;
_m340 = .;
@ -244,47 +245,47 @@ $BSP340_ROOT/startup/linkcmds.
} >ram
/*
* Initialized Data section goes in RAM
\*/
*/
.data : {
copy_start = .;
\*(.data)
*(.data)
. = ALIGN (16);
_edata = .;
copy_end = .;
} >ram
/*
* Uninitialized Data section goes in ROM
\*/
*/
.bss : {
/*
* M68K specific: Reserve some room for the Vector Table
* (256 vectors of 4 bytes).
\*/
*/
M68Kvec = .;
_M68Kvec = .;
. += (256 * 4);
/*
* Start of memory to zero out at initialization time.
\*/
*/
clear_start = .;
/*
* Put all the object files uninitialized data sections
* here.
\*/
\*(.bss)
\*(COMMON)
*/
*(.bss)
*(COMMON)
. = ALIGN (16);
_end = .;
/*
* Start of the Application Heap
\*/
*/
_HeapStart = .;
__HeapStart = .;
. += HeapSize;
/*
* The Starting Stack goes after the Application Heap.
* M68K stack grows down so start at high address.
\*/
*/
. += StackSize;
. = ALIGN (16);
stack_init = .;
@ -293,76 +294,66 @@ $BSP340_ROOT/startup/linkcmds.
* The RTEMS Executive Workspace goes here. RTEMS
* allocates tasks, stacks, semaphores, etc. from this
* memory.
\*/
*/
_WorkspaceBase = .;
__WorkspaceBase = .;
} >ram
}
Initialized Data
================
Now there's a problem with the initialized data: the ``.data`` section
has to be in RAM as this data may be modified during the program execution.
But how will the values be initialized at boot time?
Now there's a problem with the initialized data: the ``.data`` section has to
be in RAM as this data may be modified during the program execution. But how
will the values be initialized at boot time?
One approach is to place the entire program image in RAM and reload
the image in its entirety each time the program is run. This is fine
for use in a debug environment where a high-speed connection is available
between the development host computer and the target. But even in this
environment, it is cumbersome.
One approach is to place the entire program image in RAM and reload the image
in its entirety each time the program is run. This is fine for use in a debug
environment where a high-speed connection is available between the development
host computer and the target. But even in this environment, it is cumbersome.
The solution is to place a copy of the initialized data in a separate
area of memory and copy it into the proper location each time the
program is started. It is common practice to place a copy of the initialized ``.data`` section at the end of the code (``.text``) section
in ROM when building a PROM image. The GNU tool ``objcopy``
can be used for this purpose.
The solution is to place a copy of the initialized data in a separate area of
memory and copy it into the proper location each time the program is started.
It is common practice to place a copy of the initialized ``.data`` section at
the end of the code (``.text``) section in ROM when building a PROM image. The
GNU tool ``objcopy`` can be used for this purpose.
The following figure illustrates the steps a linked program goes through
to become a downloadable image.
+--------------+------+--------------------------+--------------------+
| .data (RAM) | | .data (RAM) | |
+--------------+ +--------------------------+ |
| .bss (RAM) | | .bss (RAM) | |
+--------------+ +--------------------------+--------------------+
| .text (ROM) | | .text (ROM) | .text |
+--------------+------+---------+----------+-----+--------------------+
| copy of .data (ROM) | | copy of .data | |
+---------------------+---------+----------------+--------------------+
| Step 1 | Step 2 | Step 3 |
+---------------------+--------------------------+--------------------+
+--------------+-----+--------------------+--------------------------+
| .data RAM | | .data RAM | |
+--------------+ +--------------------+ |
| .bss RAM | | .bss RAM | |
+--------------+ +--------------------+-----+--------------------+
| .text ROM | | .text ROM | | .text |
+--------------+-----+---------+----------+-----+--------------------+
| copy of .data ROM | | copy of .data | |
+--------------------+---------+----------------+--------------------+
| Step 1 |Step 2 Step 3 |
+--------------------+--------------------------+--------------------+
In Step 1, the program is linked together using the BSP linker script.
In Step 2, a copy is made of the ``.data`` section and placed
after the ``.text`` section so it can be placed in PROM. This step
is done after the linking time. There is an example
of doing this in the file $RTEMS_ROOT/make/custom/gen68340.cfg:
.. code:: c
In Step 2, a copy is made of the ``.data`` section and placed after the
``.text`` section so it can be placed in PROM. This step is done after the
linking time. There is an example of doing this in the file
$RTEMS_ROOT/make/custom/gen68340.cfg:
.. code-block:: shell
# make a PROM image using objcopy
m68k-rtems-objcopy \\
--adjust-section-vma .data= \\
\`m68k-rtems-objdump --section-headers \\
$(basename $@).exe \\
| awk '\[...]` \\
m68k-rtems-objcopy --adjust-section-vma \
.data=`m68k-rtems-objdump --section-headers $(basename $@).exe | awk '[...]'` \
$(basename $@).exe
NOTE: The address of the "copy of ``.data`` section" is
created by extracting the last address in the ``.text``
section with an ``awk`` script. The details of how
this is done are not relevant.
.. note::
Step 3 shows the final executable image as it logically appears in
the target's non-volatile program memory. The board initialization
code will copy the ""copy of ``.data`` section" (which are stored in
ROM) to their reserved location in RAM.
.. COMMENT: COPYRIGHT (c) 1988-2011.
.. COMMENT: On-Line Applications Research Corporation (OAR).
.. COMMENT: All rights reserved.
The address of the "copy of ``.data`` section" is created by extracting the
last address in the ``.text`` section with an ``awk`` script. The details
of how this is done are not relevant.
Step 3 shows the final executable image as it logically appears in the target's
non-volatile program memory. The board initialization code will copy the
""copy of ``.data`` section" (which are stored in ROM) to their reserved
location in RAM.

254
bsp_howto/makefiles.rst
View File

@ -1,169 +1,169 @@
.. comment SPDX-License-Identifier: CC-BY-SA-4.0
.. COMMENT: COPYRIGHT (c) 1988-2002.
.. COMMENT: On-Line Applications Research Corporation (OAR).
.. COMMENT: All rights reserved.
Makefiles
#########
This chapter discusses the Makefiles associated with a BSP. It does not
describe the process of configuring, building, and installing RTEMS.
This chapter will not provide detailed information about this process.
Nonetheless, it is important to remember that the general process consists
of four phases as shown here:
describe the process of configuring, building, and installing RTEMS. This
chapter will not provide detailed information about this process. Nonetheless,
it is important to remember that the general process consists of four phases as
shown here:
- .. code:: c
- ``bootstrap``
bootstrap
- ``configure``
- .. code:: c
- ``build``
configure
- ``install``
- .. code:: c
During the bootstrap phase, you are using the ``configure.ac`` and
``Makefile.am`` files as input to GNU autoconf and automake to generate a
variety of files. This is done by running the ``bootstrap`` script found at
the top of the RTEMS source tree.
build
During the configure phase, a number of files are generated. These generated
files are tailored for the specific host/target combination by the configure
script. This set of files includes the Makefiles used to actually compile and
install RTEMS.
- .. code:: c
During the build phase, the source files are compiled into object files and
libraries are built.
install
During the bootstrap phase, you are using the ``configure.ac`` and``Makefile.am`` files as input to GNU autoconf and automake to
generate a variety of files. This is done by running the ``bootstrap``
script found at the top of the RTEMS source tree.
During the configure phase, a number of files are generated. These
generated files are tailored for the specific host/target combination
by the configure script. This set of files includes the Makefiles used
to actually compile and install RTEMS.
During the build phase, the source files are compiled into object files
and libraries are built.
During the install phase, the libraries, header files, and other support
files are copied to the BSP specific installation point. After installation
is successfully completed, the files generated by the configure and build
phases may be removed.
During the install phase, the libraries, header files, and other support files
are copied to the BSP specific installation point. After installation is
successfully completed, the files generated by the configure and build phases
may be removed.
Makefiles Used During The BSP Building Process
==============================================
RTEMS uses the *GNU automake* and *GNU autoconf* automatic
configuration package. Consequently, there are a number of
automatically generated files in each directory in the RTEMS
source tree. The ``bootstrap`` script found in the top level
directory of the RTEMS source tree is executed to produce the
automatically generated files. That script must be run from
a directory with a ``configure.ac`` file in it. The ``bootstrap``
command is usually invoked in one of the following manners:
RTEMS uses the *GNU automake* and *GNU autoconf* automatic configuration
package. Consequently, there are a number of automatically generated files in
each directory in the RTEMS source tree. The ``bootstrap`` script found in the
top level directory of the RTEMS source tree is executed to produce the
automatically generated files. That script must be run from a directory with a
``configure.ac`` file in it. The ``bootstrap`` command is usually invoked in
one of the following manners:
- ``bootstrap`` to regenerate all files that are generated by
autoconf and automake.
- ``bootstrap -c`` to remove all files generated by autoconf and
- ``bootstrap`` to regenerate all files that are generated by autoconf and
automake.
- ``bootstrap -c`` to remove all files generated by autoconf and automake.
- ``bootstrap -p`` to regenerate ``preinstall.am`` files.
There is a file named ``Makefile.am`` in each directory of
a BSP. This file is used by *automake* to produce the file named``Makefile.in`` which is also found in each directory of a BSP.
When modifying a ``Makefile.am``, you can probably find examples of
anything you need to do in one of the BSPs.
There is a file named ``Makefile.am`` in each directory of a BSP. This file is
used by *automake* to produce the file named ``Makefile.in`` which is also
found in each directory of a BSP. When modifying a ``Makefile.am``, you can
probably find examples of anything you need to do in one of the BSPs.
The configure process specializes the ``Makefile.in`` files at the time that RTEMS
is configured for a specific development host and target. Makefiles
are automatically generated from the ``Makefile.in`` files. It is
necessary for the BSP developer to provide the ``Makefile.am``
files and generate the ``Makefile.in`` files. Most of the
time, it is possible to copy the ``Makefile.am`` from another
similar directory and edit it.
The configure process specializes the ``Makefile.in`` files at the time that
RTEMS is configured for a specific development host and target. Makefiles are
automatically generated from the ``Makefile.in`` files. It is necessary for
the BSP developer to provide the ``Makefile.am`` files and generate the
``Makefile.in`` files. Most of the time, it is possible to copy the
``Makefile.am`` from another similar directory and edit it.
The ``Makefile`` files generated are processed when configuring
and building RTEMS for a given BSP.
The ``Makefile`` files generated are processed when configuring and building
RTEMS for a given BSP.
The BSP developer is responsible for generating ``Makefile.am``
files which properly build all the files associated with their BSP.
Most BSPs will only have a single ``Makefile.am`` which details
the set of source files to build to compose the BSP support library
along with the set of include files that are to be installed.
The BSP developer is responsible for generating ``Makefile.am`` files which
properly build all the files associated with their BSP. Most BSPs will only
have a single ``Makefile.am`` which details the set of source files to build to
compose the BSP support library along with the set of include files that are to
be installed.
This single ``Makefile.am`` at the top of the BSP tree specifies
the set of header files to install. This fragment from the SPARC/ERC32
BSP results in four header files being installed.
.. code:: c
This single ``Makefile.am`` at the top of the BSP tree specifies the set of
header files to install. This fragment from the SPARC/ERC32 BSP results in
four header files being installed.
.. code-block:: makefile
include_HEADERS = include/bsp.h
include_HEADERS += include/tm27.h
include_HEADERS += include/erc32.h
include_HEADERS += include/coverhd.h
When adding new include files, you will be adding to the set of``include_HEADERS``. When you finish editing the ``Makefile.am``
file, do not forget to run ``bootstrap -p`` to regenerate the``preinstall.am``.
When adding new include files, you will be adding to the set of
``include_HEADERS``. When you finish editing the ``Makefile.am`` file, do not
forget to run ``bootstrap -p`` to regenerate the ``preinstall.am``.
The ``Makefile.am`` also specifies which source files to build.
By convention, logical components within the BSP each assign their
source files to a unique variable. These variables which define
the source files are collected into a single variable which instructs
the GNU autotools that we are building ``libbsp.a``. This fragment
from the SPARC/ERC32 BSP shows how the startup related, miscellaneous
support code, and the console device driver source is managed
in the ``Makefile.am``.
.. code:: c
The ``Makefile.am`` also specifies which source files to build. By convention,
logical components within the BSP each assign their source files to a unique
variable. These variables which define the source files are collected into a
single variable which instructs the GNU autotools that we are building
``libbsp.a``. This fragment from the SPARC/ERC32 BSP shows how the startup
related, miscellaneous support code, and the console device driver source is
managed in the ``Makefile.am``.
startup_SOURCES = ../../sparc/shared/bspclean.c ../../shared/bsplibc.c \\
../../shared/bsppredriverhook.c \\
../../shared/bsppost.c ../../sparc/shared/bspstart.c \\
../../shared/bootcard.c ../../shared/sbrk.c startup/setvec.c \\
.. code-block:: makefile
startup_SOURCES = ../../sparc/shared/bspclean.c ../../shared/bsplibc.c \
../../shared/bsppredriverhook.c \
../../shared/bsppost.c ../../sparc/shared/bspstart.c \
../../shared/bootcard.c ../../shared/sbrk.c startup/setvec.c \
startup/spurious.c startup/erc32mec.c startup/boardinit.S
clock_SOURCES = clock/ckinit.c
...
noinst_LIBRARIES = libbsp.a
libbsp_a_SOURCES = $(startup_SOURCES) $(console_SOURCES) ...
When adding new files to an existing directory, do not forget to add
the new files to the list of files to be built in the corresponding``XXX_SOURCES`` variable in the ``Makefile.am`` and run``bootstrap``.
When adding new files to an existing directory, do not forget to add the new
files to the list of files to be built in the corresponding ``XXX_SOURCES``
variable in the ``Makefile.am`` and run``bootstrap``.
Some BSPs use code that is built in ``libcpu``. If you BSP does
this, then you will need to make sure the objects are pulled into your
BSP library. The following from the SPARC/ERC32 BSP pulls in the cache,
register window management and system call support code from the directory
corresponding to its ``RTEMS_CPU`` model.
.. code:: c
Some BSPs use code that is built in ``libcpu``. If you BSP does this, then you
will need to make sure the objects are pulled into your BSP library. The
following from the SPARC/ERC32 BSP pulls in the cache, register window
management and system call support code from the directory corresponding to its
``RTEMS_CPU`` model.
libbsp_a_LIBADD = ../../../libcpu/@RTEMS_CPU@/cache.rel \\
../../../libcpu/@RTEMS_CPU@/reg_win.rel \\
.. code-block:: makefile
libbsp_a_LIBADD = ../../../libcpu/@RTEMS_CPU@/cache.rel \
../../../libcpu/@RTEMS_CPU@/reg_win.rel \
../../../libcpu/@RTEMS_CPU@/syscall.rel
*NOTE:* The ``Makefile.am`` files are ONLY processed by``bootstrap`` and the resulting ``Makefile.in`` files are only
processed during the configure process of a RTEMS build. Therefore,
when developing a BSP and adding a new file to a ``Makefile.am``,
the already generated ``Makefile`` will not automatically
include the new references unless you configured RTEMS with the``--enable-maintainer-mode`` option. Otherwise, the new file not
being be taken into account!
.. note:
The ``Makefile.am`` files are ONLY processed by ``bootstrap`` and the resulting
``Makefile.in`` files are only processed during the configure process of a
RTEMS build. Therefore, when developing a BSP and adding a new file to a
``Makefile.am``, the already generated ``Makefile`` will not automatically
include the new references unless you configured RTEMS with the
``--enable-maintainer-mode`` option. Otherwise, the new file will not being be
taken into account!
Creating a New BSP Make Customization File
==========================================
When building a BSP or an application using that BSP, it is necessary
to tailor the compilation arguments to account for compiler flags, use
custom linker scripts, include the RTEMS libraries, etc.. The BSP
must be built using this information. Later, once the BSP is installed
with the toolset, this same information must be used when building the
application. So a BSP must include a build configuration file. The
configuration file is ``make/custom/BSP.cfg``.
When building a BSP or an application using that BSP, it is necessary to tailor
the compilation arguments to account for compiler flags, use custom linker
scripts, include the RTEMS libraries, etc.. The BSP must be built using this
information. Later, once the BSP is installed with the toolset, this same
information must be used when building the application. So a BSP must include
a build configuration file. The configuration file is ``make/custom/BSP.cfg``.
The configuration file is taken into account when building one's
application using the RTEMS template Makefiles (``make/templates``).
These application template Makefiles have been included with the
RTEMS source distribution since the early 1990's. However there is
a desire in the RTEMS user community to move all provided examples to
GNU autoconf. They are included in the 4.9 release series and used for
all examples provided with RTEMS. There is no definite time table for
obsoleting them. You are free to use these but be warned they have
fallen out of favor with many in the RTEMS community and may disappear
in the future.
The configuration file is taken into account when building one's application
using the RTEMS template Makefiles (``make/templates``). These application
template Makefiles have been included with the RTEMS source distribution since
the early 1990's. However there is a desire in the RTEMS user community to
move all provided examples to GNU autoconf. They are included in the 4.9
release series and used for all examples provided with RTEMS. There is no
definite time table for obsoleting them. You are free to use these but be
warned they have fallen out of favor with many in the RTEMS community and may
disappear in the future.
The following is a slightly shortened version of the make customization
file for the gen68340 BSP. The original source for this file can be
found in the ``make/custom`` directory.
.. code:: c
The following is a slightly shortened version of the make customization file
for the gen68340 BSP. The original source for this file can be found in the
``make/custom`` directory.
.. code-block:: makefile
# The RTEMS CPU Family and Model
RTEMS_CPU=m68k
@ -177,20 +177,12 @@ found in the ``make/custom`` directory.
# optimize flag: typically -O2
CFLAGS_OPTIMIZE_V = -O2 -g -fomit-frame-pointer
The make customization files have generally grown simpler and simpler
with each RTEMS release. Beginning in the 4.9 release series, the rules
for linking an RTEMS application are shared by all BSPs. Only BSPs which
need to perform a transformation from linked ELF file to a downloadable
format have any additional actions for program link time. In 4.8 and
older, every BSP specified the "make executable" or ``make-exe``
rule and duplicated the same actions.
It is generally easier to copy a ``make/custom`` file from a
BSP similar to the one being developed.
.. COMMENT: COPYRIGHT (c) 1988-2002.
.. COMMENT: On-Line Applications Research Corporation (OAR).
.. COMMENT: All rights reserved.
The make customization files have generally grown simpler and simpler with each
RTEMS release. Beginning in the 4.9 release series, the rules for linking an
RTEMS application are shared by all BSPs. Only BSPs which need to perform a
transformation from linked ELF file to a downloadable format have any
additional actions for program link time. In 4.8 and older, every BSP specified
the "make executable" or ``make-exe`` rule and duplicated the same actions.
It is generally easier to copy a ``make/custom`` file from a BSP similar to the
one being developed.

402
bsp_howto/miscellanous_support.rst
View File

@ -1,70 +1,73 @@
.. comment SPDX-License-Identifier: CC-BY-SA-4.0
.. COMMENT: COPYRIGHT (c) 1988-2002.
.. COMMENT: On-Line Applications Research Corporation (OAR).
.. COMMENT: All rights reserved.
Miscellaneous Support Files
###########################
GCC Compiler Specifications File
================================
The file ``bsp_specs`` defines the start files and libraries
that are always used with this BSP. The format of this file
is admittedly cryptic and this document will make no attempt
to explain it completely. Below is the ``bsp_specs``
file from the PowerPC psim BSP:
.. code:: c
The file ``bsp_specs`` defines the start files and libraries that are always
used with this BSP. The format of this file is admittedly cryptic and this
document will make no attempt to explain it completely. Below is the
``bsp_specs`` file from the PowerPC psim BSP:
.. code-block:: c
%rename endfile old_endfile
%rename startfile old_startfile
%rename link old_link
\*startfile:
%{!qrtems: %(old_startfile)} \\
*startfile:
%{!qrtems: %(old_startfile)} \
%{!nostdlib: %{qrtems: ecrti%O%s rtems_crti%O%s crtbegin.o%s start.o%s}}
\*link:
*link:
%{!qrtems: %(old_link)} %{qrtems: -Qy -dp -Bstatic -e _start -u __vectors}
\*endfile:
*endfile:
%{!qrtems: %(old_endfile)} %{qrtems: crtend.o%s ecrtn.o%s}
The first section of this file renames the built-in definition of
some specification variables so they can be augmented without
embedded their original definition. The subsequent sections
specify what behavior is expected when the ``-qrtems`` option is specified.
The first section of this file renames the built-in definition of some
specification variables so they can be augmented without embedded their
original definition. The subsequent sections specify what behavior is expected
when the ``-qrtems`` option is specified.
The ``*startfile`` section specifies that the BSP specific file``start.o`` will be used instead of ``crt0.o``. In addition,
various EABI support files (``ecrti.o`` etc.) will be linked in with
the executable.
The ``*startfile`` section specifies that the BSP specific file ``start.o``
will be used instead of ``crt0.o``. In addition, various EABI support files
(``ecrti.o`` etc.) will be linked in with the executable.
The ``*link`` section adds some arguments to the linker when it is
invoked by GCC to link an application for this BSP.
The ``*link`` section adds some arguments to the linker when it is invoked by
GCC to link an application for this BSP.
The format of this file is specific to the GNU Compiler Suite. The
argument used to override and extend the compiler built-in specifications
is available in all recent GCC versions. The ``-specs`` option is
present in all ``egcs`` distributions and ``gcc`` distributions
starting with version 2.8.0.
The format of this file is specific to the GNU Compiler Suite. The argument
used to override and extend the compiler built-in specifications is available
in all recent GCC versions. The ``-specs`` option is present in all ``egcs``
distributions and ``gcc`` distributions starting with version 2.8.0.
README Files
============
Most BSPs provide one or more ``README`` files. Generally, there
is a ``README`` file at the top of the BSP source. This file
describes the board and its hardware configuration, provides vendor
information, local configuration information, information on downloading
code to the board, debugging, etc.. The intent of this
file is to help someone begin to use the BSP faster.
Most BSPs provide one or more ``README`` files. Generally, there is a
``README`` file at the top of the BSP source. This file describes the board
and its hardware configuration, provides vendor information, local
configuration information, information on downloading code to the board,
debugging, etc.. The intent of this file is to help someone begin to use the
BSP faster.
A ``README`` file in a BSP subdirectory typically explains something
about the contents of that subdirectory in greater detail. For example,
it may list the documentation available for a particular peripheral
controller and how to obtain that documentation. It may also explain some
particularly cryptic part of the software in that directory or provide
rationale on the implementation.
A ``README`` file in a BSP subdirectory typically explains something about the
contents of that subdirectory in greater detail. For example, it may list the
documentation available for a particular peripheral controller and how to
obtain that documentation. It may also explain some particularly cryptic part
of the software in that directory or provide rationale on the implementation.
times
=====
This file contains the results of the RTEMS Timing Test Suite. It is
in a standard format so that results from one BSP can be easily compared
with those of another target board.
This file contains the results of the RTEMS Timing Test Suite. It is in a
standard format so that results from one BSP can be easily compared with those
of another target board.
If a BSP supports multiple variants, then there may be multiple ``times``
files. Usually these are named ``times.VARIANTn``.
@ -72,75 +75,74 @@ files. Usually these are named ``times.VARIANTn``.
Tools Subdirectory
==================
Some BSPs provide additional tools that aid in using the target board.
These tools run on the development host and are built as part of building
the BSP. Most common is a script to automate running the RTEMS Test Suites
on the BSP. Examples of this include:
Some BSPs provide additional tools that aid in using the target board. These
tools run on the development host and are built as part of building the BSP.
Most common is a script to automate running the RTEMS Test Suites on the BSP.
Examples of this include:
- ``powerpc/psim`` includes scripts to ease use of the simulator
- ``m68k/mvme162`` includes a utility to download across the
VMEbus into target memory if the host is a VMEbus board in the same
chasis.
- ``m68k/mvme162`` includes a utility to download across the VMEbus into target
memory if the host is a VMEbus board in the same chasis.
bsp.h Include File
==================
The file ``include/bsp.h`` contains prototypes and definitions
specific to this board. Every BSP is required to provide a ``bsp.h``.
The best approach to writing a ``bsp.h`` is copying an existing one
as a starting point.
The file ``include/bsp.h`` contains prototypes and definitions specific to this
board. Every BSP is required to provide a ``bsp.h``. The best approach to
writing a ``bsp.h`` is copying an existing one as a starting point.
Many ``bsp.h`` files provide prototypes of variables defined
in the linker script (``linkcmds``).
Many ``bsp.h`` files provide prototypes of variables defined in the linker
script (``linkcmds``).
tm27.h Include File
===================
The ``tm27`` test from the RTEMS Timing Test Suite is designed to measure the length of time required to vector to and return from an interrupt handler. This test requires some help from the BSP to know how to cause and manipulate the interrupt source used for this measurement. The following is a list of these:
The ``tm27`` test from the RTEMS Timing Test Suite is designed to measure the
length of time required to vector to and return from an interrupt handler. This
test requires some help from the BSP to know how to cause and manipulate the
interrupt source used for this measurement. The following is a list of these:
- ``MUST_WAIT_FOR_INTERRUPT`` - modifies behavior of ``tm27``.
- ``Install_tm27_vector`` - installs the interrupt service
routine for the Interrupt Benchmark Test (``tm27``).
- ``Install_tm27_vector`` - installs the interrupt service routine for the
Interrupt Benchmark Test (``tm27``).
- ``Cause_tm27_intr`` - generates the interrupt source
used in the Interrupt Benchmark Test (``tm27``).
- ``Cause_tm27_intr`` - generates the interrupt source used in the Interrupt
Benchmark Test (``tm27``).
- ``Clear_tm27_intr`` - clears the interrupt source
used in the Interrupt Benchmark Test (``tm27``).
- ``Clear_tm27_intr`` - clears the interrupt source used in the Interrupt
Benchmark Test (``tm27``).
- ``Lower_tm27_intr`` - lowers the interrupt mask so the
interrupt source used in the Interrupt Benchmark Test (``tm27``)
can generate a nested interrupt.
- ``Lower_tm27_intr`` - lowers the interrupt mask so the interrupt source used
in the Interrupt Benchmark Test (``tm27``) can generate a nested interrupt.
All members of the Timing Test Suite are designed to run *WITHOUT*
the Clock Device Driver installed. This increases the predictability
of the tests' execution as well as avoids occassionally including the
overhead of a clock tick interrupt in the time reported. Because of
this it is sometimes possible to use the clock tick interrupt source
as the source of this test interrupt. On other architectures, it is
possible to directly force an interrupt to occur.
All members of the Timing Test Suite are designed to run *WITHOUT* the Clock
Device Driver installed. This increases the predictability of the tests'
execution as well as avoids occassionally including the overhead of a clock
tick interrupt in the time reported. Because of this it is sometimes possible
to use the clock tick interrupt source as the source of this test interrupt.
On other architectures, it is possible to directly force an interrupt to occur.
Calling Overhead File
=====================
The file ``include/coverhd.h`` contains the overhead associated
with invoking each directive. This overhead consists of the execution
time required to package the parameters as well as to execute the "jump to
subroutine" and "return from subroutine" sequence. The intent of this
file is to help separate the calling overhead from the actual execution
time of a directive. This file is only used by the tests in the
RTEMS Timing Test Suite.
The file ``include/coverhd.h`` contains the overhead associated with invoking
each directive. This overhead consists of the execution time required to
package the parameters as well as to execute the "jump to subroutine" and
"return from subroutine" sequence. The intent of this file is to help separate
the calling overhead from the actual execution time of a directive. This file
is only used by the tests in the RTEMS Timing Test Suite.
The numbers in this file are obtained by running the "Timer Overhead"``tmoverhd`` test. The numbers in this file may be 0 and no
overhead is subtracted from the directive execution times reported by
the Timing Suite.
The numbers in this file are obtained by running the "Timer
Overhead"``tmoverhd`` test. The numbers in this file may be 0 and no overhead
is subtracted from the directive execution times reported by the Timing Suite.
There is a shared implementation of ``coverhd.h`` which sets all of the
overhead constants to 0. On faster processors, this is usually the best
alternative for the BSP as the calling overhead is extremely small. This file
is located at:
There is a shared implementation of ``coverhd.h`` which sets all of
the overhead constants to 0. On faster processors, this is usually the
best alternative for the BSP as the calling overhead is extremely small.
This file is located at:
.. code:: c
c/src/lib/libbsp/shared/include/coverhd.h
@ -148,20 +150,28 @@ This file is located at:
sbrk() Implementation
=====================
Although nearly all BSPs give all possible memory to the C Program Heap
at initialization, it is possible for a BSP to configure the initial
size of the heap small and let it grow on demand. If the BSP wants
to dynamically extend the heap used by the C Library memory allocation
routines (i.e. ``malloc`` family), then the``sbrk`` routine must
be functional. The following is the prototype for this routine:
Although nearly all BSPs give all possible memory to the C Program Heap at
initialization, it is possible for a BSP to configure the initial size of the
heap small and let it grow on demand. If the BSP wants to dynamically extend
the heap used by the C Library memory allocation routines (i.e. ``malloc``
family), then the``sbrk`` routine must be functional. The following is the
prototype for this routine:
.. code:: c
void * sbrk(size_t increment)
The ``increment`` amount is based upon the ``sbrk_amount``
parameter passed to the ``bsp_libc_init`` during system initialization... index:: CONFIGURE_MALLOC_BSP_SUPPORTS_SBRK
The ``increment`` amount is based upon the ``sbrk_amount`` parameter passed to
the ``bsp_libc_init`` during system initialization.
If your BSP does not want to support dynamic heap extension, then you do not have to do anything special. However, if you want to support ``sbrk``, you must provide an implementation of this method and define ``CONFIGURE_MALLOC_BSP_SUPPORTS_SBRK`` in ``bsp.h``. This informs ``rtems/confdefs.h`` to configure the Malloc Family Extensions which support ``sbrk``.
.. index:: CONFIGURE_MALLOC_BSP_SUPPORTS_SBRK
If your BSP does not want to support dynamic heap extension, then you do not
have to do anything special. However, if you want to support ``sbrk``, you
must provide an implementation of this method and define
``CONFIGURE_MALLOC_BSP_SUPPORTS_SBRK`` in ``bsp.h``. This informs
``rtems/confdefs.h`` to configure the Malloc Family Extensions which support
``sbrk``.
bsp_fatal_extension() - Cleanup the Hardware
============================================
@ -170,81 +180,83 @@ The ``bsp_fatal_extension()`` is an optional BSP specific initial extension
invoked once a fatal system state is reached. Most of the BSPs use the same
shared version of ``bsp_fatal_extension()`` that does nothing or performs a
system reset. This implementation is located in the following file:
.. code:: c
c/src/lib/libbsp/shared/bspclean.c
The ``bsp_fatal_extension()`` routine can be used to return to a ROM
monitor, insure that interrupt sources are disabled, etc.. This routine is the
last place to ensure a clean shutdown of the hardware. The fatal source,
internal error indicator, and the fatal code arguments are available to
evaluate the fatal condition. All of the non-fatal shutdown sequences
ultimately pass their exit status to ``rtems_shutdown_executive`` and this
is what is passed to this routine in case the fatal source is
RTEMS_FATAL_SOURCE_EXIT.
The ``bsp_fatal_extension()`` routine can be used to return to a ROM monitor,
insure that interrupt sources are disabled, etc.. This routine is the last
place to ensure a clean shutdown of the hardware. The fatal source, internal
error indicator, and the fatal code arguments are available to evaluate the
fatal condition. All of the non-fatal shutdown sequences ultimately pass their
exit status to ``rtems_shutdown_executive`` and this is what is passed to this
routine in case the fatal source is ``RTEMS_FATAL_SOURCE_EXIT``.
On some BSPs, it prints a message indicating that the application
completed execution and waits for the user to press a key before
resetting the board. The PowerPC/gen83xx and PowerPC/gen5200 BSPs do
this when they are built to support the FreeScale evaluation boards.
This is convenient when using the boards in a development environment
and may be disabled for production use.
On some BSPs, it prints a message indicating that the application completed
execution and waits for the user to press a key before resetting the board.
The PowerPC/gen83xx and PowerPC/gen5200 BSPs do this when they are built to
support the FreeScale evaluation boards. This is convenient when using the
boards in a development environment and may be disabled for production use.
Configuration Macros
====================
Each BSP can define macros in bsp.h which alter some of the the default configuration parameters in ``rtems/confdefs.h``. This section describes those macros:
Each BSP can define macros in bsp.h which alter some of the the default
configuration parameters in ``rtems/confdefs.h``. This section describes those
macros:
- .. index:: CONFIGURE_MALLOC_BSP_SUPPORTS_SBRK
.. index:: CONFIGURE_MALLOC_BSP_SUPPORTS_SBRK
``CONFIGURE_MALLOC_BSP_SUPPORTS_SBRK`` must be defined if the
BSP has proper support for ``sbrk``. This is discussed in more detail
in the previous section.
- ``CONFIGURE_MALLOC_BSP_SUPPORTS_SBRK`` must be defined if the BSP has proper
support for ``sbrk``. This is discussed in more detail in the previous
section.
- .. index:: BSP_IDLE_TASK_BODY
.. index:: BSP_IDLE_TASK_BODY
``BSP_IDLE_TASK_BODY`` may be defined to the entry point of a
BSP specific IDLE thread implementation. This may be overridden if the
application provides its own IDLE task implementation.
- ``BSP_IDLE_TASK_BODY`` may be defined to the entry point of a BSP specific
IDLE thread implementation. This may be overridden if the application
provides its own IDLE task implementation.
- .. index:: BSP_IDLE_TASK_STACK_SIZE
.. index:: BSP_IDLE_TASK_STACK_SIZE
``BSP_IDLE_TASK_STACK_SIZE`` may be defined to the desired
default stack size for the IDLE task as recommended when using this BSP.
- ``BSP_IDLE_TASK_STACK_SIZE`` may be defined to the desired default stack size
for the IDLE task as recommended when using this BSP.
- .. index:: BSP_INTERRUPT_STACK_SIZE
.. index:: BSP_INTERRUPT_STACK_SIZE
``BSP_INTERRUPT_STACK_SIZE`` may be defined to the desired default interrupt stack size as recommended when using this BSP. This is sometimes required when the BSP developer has knowledge of stack intensive interrupt handlers.
- ``BSP_INTERRUPT_STACK_SIZE`` may be defined to the desired default interrupt
stack size as recommended when using this BSP. This is sometimes required
when the BSP developer has knowledge of stack intensive interrupt handlers.
- .. index:: BSP_ZERO_WORKSPACE_AUTOMATICALLY
.. index:: BSP_ZERO_WORKSPACE_AUTOMATICALLY
``BSP_ZERO_WORKSPACE_AUTOMATICALLY`` is defined when the BSP
requires that RTEMS zero out the RTEMS C Program Heap at initialization.
If the memory is already zeroed out by a test sequence or boot ROM,
then the boot time can be reduced by not zeroing memory twice.
- ``BSP_ZERO_WORKSPACE_AUTOMATICALLY`` is defined when the BSP requires that
RTEMS zero out the RTEMS C Program Heap at initialization. If the memory is
already zeroed out by a test sequence or boot ROM, then the boot time can be
reduced by not zeroing memory twice.
- .. index:: BSP_DEFAULT_UNIFIED_WORK_AREAS
.. index:: BSP_DEFAULT_UNIFIED_WORK_AREAS
``BSP_DEFAULT_UNIFIED_WORK_AREAS`` is defined when the BSP
recommends that the unified work areas configuration should always
be used. This is desirable when the BSP is known to always have very
little RAM and thus saving memory by any means is desirable.
- ``BSP_DEFAULT_UNIFIED_WORK_AREAS`` is defined when the BSP recommends that
the unified work areas configuration should always be used. This is
desirable when the BSP is known to always have very little RAM and thus
saving memory by any means is desirable.
set_vector() - Install an Interrupt Vector
==========================================
On targets with Simple Vectored Interrupts, the BSP must provide
an implementation of the ``set_vector`` routine. This routine is
responsible for installing an interrupt vector. It invokes the support
routines necessary to install an interrupt handler as either a "raw"
or an RTEMS interrupt handler. Raw handlers bypass the RTEMS interrupt
structure and are responsible for saving and restoring all their own
registers. Raw handlers are useful for handling traps, debug vectors,
etc..
On targets with Simple Vectored Interrupts, the BSP must provide an
implementation of the ``set_vector`` routine. This routine is responsible for
installing an interrupt vector. It invokes the support routines necessary to
install an interrupt handler as either a "raw" or an RTEMS interrupt handler.
Raw handlers bypass the RTEMS interrupt structure and are responsible for
saving and restoring all their own registers. Raw handlers are useful for
handling traps, debug vectors, etc.
The ``set_vector`` routine is a central place to perform interrupt
controller manipulation and encapsulate that information. It is usually
implemented as follows:
The ``set_vector`` routine is a central place to perform interrupt controller
manipulation and encapsulate that information. It is usually implemented as
follows:
.. code:: c
@ -258,95 +270,95 @@ implemented as follows:
install the raw vector
else
use rtems_interrupt_catch to install the vector
perform any interrupt controller necessary to unmask
the interrupt source
perform any interrupt controller necessary to unmask the interrupt source
return the previous handler
}
*NOTE:* The i386, PowerPC and ARM ports use a Programmable
Interrupt Controller model which does not require the BSP to implement``set_vector``. BSPs for these architectures must provide a different
set of support routines.
.. note::
The i386, PowerPC and ARM ports use a Programmable Interrupt Controller
model which does not require the BSP to implement ``set_vector``. BSPs for
these architectures must provide a different set of support routines.
Interrupt Delay Profiling
=========================
The RTEMS profiling needs support by the BSP for the interrupt delay times. In
case profiling is enabled via the RTEMS build configuration option``--enable-profiling`` (in this case the pre-processor symbol``RTEMS_PROFILING`` is defined) a BSP may provide data for the interrupt
delay times. The BSP can feed interrupt delay times with the``_Profiling_Update_max_interrupt_delay()`` function
(``#include <rtems/score/profiling.h>``). For an example please have a look
at ``c/src/lib/libbsp/sparc/leon3/clock/ckinit.c``.
case profiling is enabled via the RTEMS build configuration option
``--enable-profiling`` (in this case the pre-processor symbol
``RTEMS_PROFILING`` is defined) a BSP may provide data for the interrupt delay
times. The BSP can feed interrupt delay times with the
``_Profiling_Update_max_interrupt_delay()`` function (``#include
<rtems/score/profiling.h>``). For an example please have a look at
``c/src/lib/libbsp/sparc/leon3/clock/ckinit.c``.
Programmable Interrupt Controller API
=====================================
A BSP can use the PIC API to install Interrupt Service Routines through
a set of generic methods. In order to do so, the header files
libbsp/shared/include/irq-generic.h and libbsp/shared/include/irq-info.h
A BSP can use the PIC API to install Interrupt Service Routines through a set
of generic methods. In order to do so, the header files
libbsp/shared/include/irq-generic.h and ``libbsp/shared/include/irq-info.h``
must be included by the bsp specific irq.h file present in the include/
directory. The irq.h acts as a BSP interrupt support configuration file which
is used to define some important MACROS. It contains the declarations for
any required global functions like bsp_interrupt_dispatch(). Thus later on,
every call to the PIC interface requires including <bsp/irq.h>
is used to define some important MACROS. It contains the declarations for any
required global functions like bsp_interrupt_dispatch(). Thus later on, every
call to the PIC interface requires including ``<bsp/irq.h>``
The generic interrupt handler table is intitalized by invoking the``bsp_interrupt_initialize()`` method from bsp_start() in the bspstart.c
file which sets up this table to store the ISR addresses, whose size is based
on the definition of macros, BSP_INTERRUPT_VECTOR_MIN & BSP_INTERRUPT_VECTOR_MAX
in include/bsp.h
The generic interrupt handler table is intitalized by invoking the
``bsp_interrupt_initialize()`` method from bsp_start() in the bspstart.c file
which sets up this table to store the ISR addresses, whose size is based on the
definition of macros, ``BSP_INTERRUPT_VECTOR_MIN`` and
``BSP_INTERRUPT_VECTOR_MAX`` in include/bsp.h
For the generic handler table to properly function, some bsp specific code is
required, that should be present in irq/irq.c . The bsp-specific functions required
to be writen by the BSP developer are :
required, that should be present in ``irq/irq.c``. The bsp-specific functions
required to be writen by the BSP developer are :
- .. index:: bsp_interrupt_facility_initialize()
.. index:: bsp_interrupt_facility_initialize()
``bsp_interrupt_facility_initialize()`` contains bsp specific interrupt
- ``bsp_interrupt_facility_initialize()`` contains bsp specific interrupt
initialization code(Clear Pending interrupts by modifying registers, etc.).
This method is called from bsp_interrupt_initialize() internally while setting up
the table.
This method is called from ``bsp_interrupt_initialize()`` internally while
setting up the table.
- .. index:: bsp_interrupt_handler_default()
.. index:: bsp_interrupt_handler_default()
``bsp_interrupt_handler_default()`` acts as a fallback handler when
no ISR address has been provided corresponding to a vector in the table.
- ``bsp_interrupt_handler_default()`` acts as a fallback handler when no ISR
address has been provided corresponding to a vector in the table.
- .. index:: bsp_interrupt_dispatch()
.. index:: bsp_interrupt_dispatch()
``bsp_interrupt_dispatch()`` service the ISR by handling
any bsp specific code & calling the generic method bsp_interrupt_handler_dispatch()
which in turn services the interrupt by running the ISR after looking it up in
the table. It acts as an entry to the interrupt switchboard, since the bsp
- ``bsp_interrupt_dispatch()`` service the ISR by handling any bsp specific
code & calling the generic method ``bsp_interrupt_handler_dispatch()`` which
in turn services the interrupt by running the ISR after looking it up in the
table. It acts as an entry to the interrupt switchboard, since the bsp
branches to this function at the time of occurrence of an interrupt.
- .. index:: bsp_interrupt_vector_enable()
.. index:: bsp_interrupt_vector_enable()
``bsp_interrupt_vector_enable()`` enables interrupts and is called in
- ``bsp_interrupt_vector_enable()`` enables interrupts and is called in
irq-generic.c while setting up the table.
- .. index:: bsp_interrupt_vector_disable()
.. index:: bsp_interrupt_vector_disable()
``bsp_interrupt_vector_disable()`` disables interrupts and is called in
- ``bsp_interrupt_vector_disable()`` disables interrupts and is called in
irq-generic.c while setting up the table & during other important parts.
An interrupt handler is installed or removed with the help of the following functions :
.. code:: c
rtems_status_code rtems_interrupt_handler_install( /* returns status code \*/
rtems_vector_number vector, /* interrupt vector \*/
const char \*info, /* custom identification text \*/
rtems_option options, /* Type of Interrupt \*/
rtems_interrupt_handler handler, /* interrupt handler \*/
void \*arg /* parameter to be passed to handler at the time of invocation \*/
rtems_status_code rtems_interrupt_handler_install( /* returns status code */
rtems_vector_number vector, /* interrupt vector */
const char *info, /* custom identification text */
rtems_option options, /* Type of Interrupt */
rtems_interrupt_handler handler, /* interrupt handler */
void *arg /* parameter to be passed
to handler at the time of
invocation */
)
rtems_status_code rtems_interrupt_handler_remove( /* returns status code \*/
rtems_vector_number vector, /* interrupt vector \*/
rtems_interrupt_handler handler, /* interrupt handler \*/
void \*arg /* parameter to be passed to handler \*/
rtems_status_code rtems_interrupt_handler_remove( /* returns status code */
rtems_vector_number vector, /* interrupt vector */
rtems_interrupt_handler handler, /* interrupt handler */
void *arg /* parameter to be passed to handler */
)
.. COMMENT: COPYRIGHT (c) 1988-2002.
.. COMMENT: On-Line Applications Research Corporation (OAR).
.. COMMENT: All rights reserved.

370
bsp_howto/networking.rst
View File

@ -1,185 +1,183 @@
.. comment SPDX-License-Identifier: CC-BY-SA-4.0
.. COMMENT: COPYRIGHT (c) 1988-2002.
.. COMMENT: On-Line Applications Research Corporation (OAR).
.. COMMENT: All rights reserved.
Networking Driver
#################
Introduction
============
This chapter is intended to provide an introduction to the
procedure for writing RTEMS network device drivers.
The example code is taken from the 'Generic 68360' network device
driver. The source code for this driver is located in the``c/src/lib/libbsp/m68k/gen68360/network`` directory in the RTEMS
source code distribution. Having a copy of this driver at
hand when reading the following notes will help significantly.
This chapter is intended to provide an introduction to the procedure for
writing RTEMS network device drivers. The example code is taken from the
'Generic 68360' network device driver. The source code for this driver is
located in the ``c/src/lib/libbsp/m68k/gen68360/network`` directory in the
RTEMS source code distribution. Having a copy of this driver at hand when
reading the following notes will help significantly.
.. sidebar:: *Legacy Networking Stack*
This docuemntation is for the legacy FreeBSD networking stack in the RTEMS
source tree.
Learn about the network device
==============================
Before starting to write the network driver become completely
familiar with the programmer's view of the device.
The following points list some of the details of the
device that must be understood before a driver can be written.
Before starting to write the network driver become completely familiar with the
programmer's view of the device. The following points list some of the details
of the device that must be understood before a driver can be written.
- Does the device use DMA to transfer packets to and from
memory or does the processor have to
copy packets to and from memory on the device?
- Does the device use DMA to transfer packets to and from memory or does the
processor have to copy packets to and from memory on the device?
- If the device uses DMA, is it capable of forming a single
outgoing packet from multiple fragments scattered in separate
memory buffers?
- If the device uses DMA, is it capable of forming a single outgoing packet
from multiple fragments scattered in separate memory buffers?
- If the device uses DMA, is it capable of chaining multiple
outgoing packets, or does each outgoing packet require
intervention by the driver?
- If the device uses DMA, is it capable of chaining multiple outgoing packets,
or does each outgoing packet require intervention by the driver?
- Does the device automatically pad short frames to the minimum
64 bytes or does the driver have to supply the padding?
- Does the device automatically pad short frames to the minimum 64 bytes or
does the driver have to supply the padding?
- Does the device automatically retry a transmission on detection
of a collision?
- Does the device automatically retry a transmission on detection of a
collision?
- If the device uses DMA, is it capable of buffering multiple
packets to memory, or does the receiver have to be restarted
after the arrival of each packet?
- If the device uses DMA, is it capable of buffering multiple packets to
memory, or does the receiver have to be restarted after the arrival of each
packet?
- How are packets that are too short, too long, or received with
CRC errors handled? Does the device automatically continue
reception or does the driver have to intervene?
- How are packets that are too short, too long, or received with CRC errors
handled? Does the device automatically continue reception or does the driver
have to intervene?
- How is the device Ethernet address set? How is the device
programmed to accept or reject broadcast and multicast packets?
- How is the device Ethernet address set? How is the device programmed to
accept or reject broadcast and multicast packets?
- What interrupts does the device generate? Does it generate an
interrupt for each incoming packet, or only for packets received
without error? Does it generate an interrupt for each packet
transmitted, or only when the transmit queue is empty? What
happens when a transmit error is detected?
- What interrupts does the device generate? Does it generate an interrupt for
each incoming packet, or only for packets received without error? Does it
generate an interrupt for each packet transmitted, or only when the transmit
queue is empty? What happens when a transmit error is detected?
In addition, some controllers have specific questions regarding
board specific configuration. For example, the SONIC Ethernet
controller has a very configurable data bus interface. It can
even be configured for sixteen and thirty-two bit data buses. This
type of information should be obtained from the board vendor.
In addition, some controllers have specific questions regarding board specific
configuration. For example, the SONIC Ethernet controller has a very
configurable data bus interface. It can even be configured for sixteen and
thirty-two bit data buses. This type of information should be obtained from
the board vendor.
Understand the network scheduling conventions
=============================================
When writing code for the driver transmit and receive tasks,
take care to follow the network scheduling conventions. All tasks
which are associated with networking share various
data structures and resources. To ensure the consistency
of these structures the tasks
execute only when they hold the network semaphore (``rtems_bsdnet_semaphore``).
The transmit and receive tasks must abide by this protocol. Be very
careful to avoid 'deadly embraces' with the other network tasks.
A number of routines are provided to make it easier for the network
driver code to conform to the network task scheduling conventions.
When writing code for the driver transmit and receive tasks, take care to
follow the network scheduling conventions. All tasks which are associated with
networking share various data structures and resources. To ensure the
consistency of these structures the tasks execute only when they hold the
network semaphore (``rtems_bsdnet_semaphore``). The transmit and receive tasks
must abide by this protocol. Be very careful to avoid 'deadly embraces' with
the other network tasks. A number of routines are provided to make it easier
for the network driver code to conform to the network task scheduling
conventions.
- ``void rtems_bsdnet_semaphore_release(void)``
This function releases the network semaphore.
The network driver tasks must call this function immediately before
making any blocking RTEMS request.
This function releases the network semaphore. The network driver tasks must
call this function immediately before making any blocking RTEMS request.
- ``void rtems_bsdnet_semaphore_obtain(void)``
This function obtains the network semaphore.
If a network driver task has released the network semaphore to allow other
network-related tasks to run while the task blocks, then this function must
be called to reobtain the semaphore immediately after the return from the
blocking RTEMS request.
This function obtains the network semaphore. If a network driver task has
released the network semaphore to allow other network-related tasks to run
while the task blocks, then this function must be called to reobtain the
semaphore immediately after the return from the blocking RTEMS request.
- ``rtems_bsdnet_event_receive(rtems_event_set, rtems_option, rtems_interval, rtems_event_set \*)``
The network driver task should call this function when it wishes to wait
for an event. This function releases the network semaphore,
calls ``rtems_event_receive`` to wait for the specified event
or events and reobtains the semaphore.
The value returned is the value returned by the ``rtems_event_receive``.
- ``rtems_bsdnet_event_receive(rtems_event_set, rtems_option, rtems_interval,
rtems_event_set *)``
The network driver task should call this function when it wishes to wait for
an event. This function releases the network semaphore, calls
``rtems_event_receive`` to wait for the specified event or events and
reobtains the semaphore. The value returned is the value returned by the
``rtems_event_receive``.
Network Driver Makefile
=======================
Network drivers are considered part of the BSD network package and as such
are to be compiled with the appropriate flags. This can be accomplished by
adding ``-D__INSIDE_RTEMS_BSD_TCPIP_STACK__`` to the ``command line``.
If the driver is inside the RTEMS source tree or is built using the
RTEMS application Makefiles, then adding the following line accomplishes
this:
Network drivers are considered part of the BSD network package and as such are
to be compiled with the appropriate flags. This can be accomplished by adding
``-D__INSIDE_RTEMS_BSD_TCPIP_STACK__`` to the ``command line``. If the driver
is inside the RTEMS source tree or is built using the RTEMS application
Makefiles, then adding the following line accomplishes this:
.. code:: c
.. code-block:: makefile
DEFINES += -D__INSIDE_RTEMS_BSD_TCPIP_STACK__
This is equivalent to the following list of definitions. Early versions
of the RTEMS BSD network stack required that all of these be defined.
This is equivalent to the following list of definitions. Early versions of the
RTEMS BSD network stack required that all of these be defined.
.. code:: c
.. code-block:: makefile
-D_COMPILING_BSD_KERNEL_ -DKERNEL -DINET -DNFS \\
-DDIAGNOSTIC -DBOOTP_COMPAT
-D_COMPILING_BSD_KERNEL_ -DKERNEL -DINET -DNFS -DDIAGNOSTIC -DBOOTP_COMPAT
Defining these macros tells the network header files that the driver
is to be compiled with extended visibility into the network stack. This
is in sharp contrast to applications that simply use the network stack.
Applications do not require this level of visibility and should stick
to the portable application level API.
Defining these macros tells the network header files that the driver is to be
compiled with extended visibility into the network stack. This is in sharp
contrast to applications that simply use the network stack. Applications do
not require this level of visibility and should stick to the portable
application level API.
As a direct result of being logically internal to the network stack,
network drivers use the BSD memory allocation routines This means,
for example, that malloc takes three arguments. See the SONIC
device driver (``c/src/lib/libchip/network/sonic.c``) for an example
of this. Because of this, network drivers should not include``<stdlib.h>``. Doing so will result in conflicting definitions
of ``malloc()``.
As a direct result of being logically internal to the network stack, network
drivers use the BSD memory allocation routines This means, for example, that
malloc takes three arguments. See the SONIC device driver
(``c/src/lib/libchip/network/sonic.c``) for an example of this. Because of
this, network drivers should not include ``<stdlib.h>``. Doing so will result
in conflicting definitions of ``malloc()``.
*Application level* code including network servers such as the FTP
daemon are *not* part of the BSD kernel network code and should not be
compiled with the BSD network flags. They should include``<stdlib.h>`` and not define the network stack visibility
macros.
*Application level* code including network servers such as the FTP daemon are
*not* part of the BSD kernel network code and should not be compiled with the
BSD network flags. They should include ``<stdlib.h>`` and not define the
network stack visibility macros.
Write the Driver Attach Function
================================
The driver attach function is responsible for configuring the driver
and making the connection between the network stack
and the driver.
The driver attach function is responsible for configuring the driver and making
the connection between the network stack and the driver.
Driver attach functions take a pointer to an``rtems_bsdnet_ifconfig`` structure as their only argument.
and set the driver parameters based on the
values in this structure. If an entry in the configuration
structure is zero the attach function chooses an
appropriate default value for that parameter.
Driver attach functions take a pointer to an ``rtems_bsdnet_ifconfig``
structure as their only argument. and set the driver parameters based on the
values in this structure. If an entry in the configuration structure is zero
the attach function chooses an appropriate default value for that parameter.
The driver should then set up several fields in the ifnet structure
in the device-dependent data structure supplied and maintained by the driver:
The driver should then set up several fields in the ifnet structure in the
device-dependent data structure supplied and maintained by the driver:
``ifp->if_softc``
Pointer to the device-dependent data. The first entry
in the device-dependent data structure must be an ``arpcom``
structure.
Pointer to the device-dependent data. The first entry in the
device-dependent data structure must be an ``arpcom`` structure.
``ifp->if_name``
The name of the device. The network stack uses this string
and the device number for device name lookups. The device name should
be obtained from the ``name`` entry in the configuration structure.
The name of the device. The network stack uses this string and the device
number for device name lookups. The device name should be obtained from
the ``name`` entry in the configuration structure.
``ifp->if_unit``
The device number. The network stack uses this number and the
device name for device name lookups. For example, if``ifp->if_name`` is '``scc``' and ``ifp->if_unit`` is '``1``',
the full device name would be '``scc1``'. The unit number should be
obtained from the 'name' entry in the configuration structure.
The device number. The network stack uses this number and the device name
for device name lookups. For example, if ``ifp->if_name`` is ``scc`` and
``ifp->if_unit`` is ``1``, the full device name would be ``scc1``. The
unit number should be obtained from the ``name`` entry in the configuration
structure.
``ifp->if_mtu``
The maximum transmission unit for the device. For Ethernet
devices this value should almost always be 1500.
The maximum transmission unit for the device. For Ethernet devices this
value should almost always be 1500.
``ifp->if_flags``
The device flags. Ethernet devices should set the flags
to ``IFF_BROADCAST|IFF_SIMPLEX``, indicating that the
device can broadcast packets to multiple destinations
and does not receive and transmit at the same time.
The device flags. Ethernet devices should set the flags to
``IFF_BROADCAST|IFF_SIMPLEX``, indicating that the device can broadcast
packets to multiple destinations and does not receive and transmit at the
same time.
``ifp->if_snd.ifq_maxlen``
The maximum length of the queue of packets waiting to be
sent to the driver. This is normally set to ``ifqmaxlen``.
The maximum length of the queue of packets waiting to be sent to the
driver. This is normally set to ``ifqmaxlen``.
``ifp->if_init``
The address of the driver initialization function.
@ -191,91 +189,92 @@ in the device-dependent data structure supplied and maintained by the driver:
The address of the driver ioctl function.
``ifp->if_output``
The address of the output function. Ethernet devices
should set this to ``ether_output``.
The address of the output function. Ethernet devices should set this to
``ether_output``.
RTEMS provides a function to parse the driver name in the
configuration structure into a device name and unit number.
.. code:: c
RTEMS provides a function to parse the driver name in the configuration
structure into a device name and unit number.
.. code-block:: c
int rtems_bsdnet_parse_driver_name (
const struct rtems_bsdnet_ifconfig \*config,
char \**namep
const struct rtems_bsdnet_ifconfig *config,
char **namep
);
The function takes two arguments; a pointer to the configuration
structure and a pointer to a pointer to a character. The function
parses the configuration name entry, allocates memory for the driver
name, places the driver name in this memory, sets the second argument
to point to the name and returns the unit number.
On error, a message is printed and -1 is returned.
The function takes two arguments; a pointer to the configuration structure and
a pointer to a pointer to a character. The function parses the configuration
name entry, allocates memory for the driver name, places the driver name in
this memory, sets the second argument to point to the name and returns the unit
number. On error, a message is printed and ``-1`` is returned.
Once the attach function has set up the above entries it must link the
driver data structure onto the list of devices by
calling ``if_attach``. Ethernet devices should then
call ``ether_ifattach``. Both functions take a pointer to the
device's ``ifnet`` structure as their only argument.
Once the attach function has set up the above entries it must link the driver
data structure onto the list of devices by calling ``if_attach``. Ethernet
devices should then call ``ether_ifattach``. Both functions take a pointer to
the device's ``ifnet`` structure as their only argument.
The attach function should return a non-zero value to indicate that
the driver has been successfully configured and attached.
The attach function should return a non-zero value to indicate that the driver
has been successfully configured and attached.
Write the Driver Start Function.
================================
This function is called each time the network stack wants to start the
transmitter. This occures whenever the network stack adds a packet
to a device's send queue and the ``IFF_OACTIVE`` bit in the
device's ``if_flags`` is not set.
transmitter. This occures whenever the network stack adds a packet to a
device's send queue and the ``IFF_OACTIVE`` bit in the device's ``if_flags`` is
not set.
For many devices this function need only set the ``IFF_OACTIVE`` bit in the``if_flags`` and send an event to the transmit task
indicating that a packet is in the driver transmit queue.
For many devices this function need only set the ``IFF_OACTIVE`` bit in the
``if_flags`` and send an event to the transmit task indicating that a packet is
in the driver transmit queue.
Write the Driver Initialization Function.
=========================================
This function should initialize the device, attach to interrupt handler,
and start the driver transmit and receive tasks. The function
.. code:: c
This function should initialize the device, attach to interrupt handler, and
start the driver transmit and receive tasks. The function:
rtems_id
rtems_bsdnet_newproc (char \*name,
.. code-block:: c
rtems_id rtems_bsdnet_newproc(
char *name,
int stacksize,
void(\*entry)(void \*),
void \*arg);
void (*entry)(void *),
void *arg
);
should be used to start the driver tasks.
Note that the network stack may call the driver initialization function more
than once.
Make sure multiple versions of the receive and transmit tasks are not accidentally
started.
than once. Make sure multiple versions of the receive and transmit tasks are
not accidentally started.
Write the Driver Transmit Task
==============================
This task is reponsible for removing packets from the driver send queue and sending them to the device. The task should block waiting for an event from the
driver start function indicating that packets are waiting to be transmitted.
When the transmit task has drained the driver send queue the task should clear
the ``IFF_OACTIVE`` bit in ``if_flags`` and block until another outgoing
packet is queued.
This task is reponsible for removing packets from the driver send queue and
sending them to the device. The task should block waiting for an event from
the driver start function indicating that packets are waiting to be
transmitted. When the transmit task has drained the driver send queue the task
should clear the ``IFF_OACTIVE`` bit in ``if_flags`` and block until another
outgoing packet is queued.
Write the Driver Receive Task
=============================
This task should block until a packet arrives from the device. If the
device is an Ethernet interface the function ``ether_input`` should be called
to forward the packet to the network stack. The arguments to ``ether_input``
are a pointer to the interface data structure, a pointer to the ethernet
header and a pointer to an mbuf containing the packet itself.
This task should block until a packet arrives from the device. If the device
is an Ethernet interface the function ``ether_input`` should be called to
forward the packet to the network stack. The arguments to ``ether_input`` are
a pointer to the interface data structure, a pointer to the ethernet header and
a pointer to an mbuf containing the packet itself.
Write the Driver Interrupt Handler
==================================
A typical interrupt handler will do nothing more than the hardware
manipulation required to acknowledge the interrupt and send an RTEMS event
to wake up the driver receive or transmit task waiting for the event.
Network interface interrupt handlers must not make any calls to other
network routines.
A typical interrupt handler will do nothing more than the hardware manipulation
required to acknowledge the interrupt and send an RTEMS event to wake up the
driver receive or transmit task waiting for the event. Network interface
interrupt handlers must not make any calls to other network routines.
Write the Driver IOCTL Function
===============================
@ -283,44 +282,29 @@ Write the Driver IOCTL Function
This function handles ioctl requests directed at the device. The ioctl
commands which must be handled are:
``SIOCGIFADDR``
``SIOCSIFADDR``
If the device is an Ethernet interface these
commands should be passed on to ``ether_ioctl``.
``SIOCGIFADDR``, ``SIOCSIFADDR``
If the device is an Ethernet interface these commands should be passed on
to ``ether_ioctl``.
``SIOCSIFFLAGS``
This command should be used to start or stop the device,
depending on the state of the interface ``IFF_UP`` and``IFF_RUNNING`` bits in ``if_flags``:
This command should be used to start or stop the device, depending on the
state of the interface ``IFF_UP`` and``IFF_RUNNING`` bits in ``if_flags``:
``IFF_RUNNING``
Stop the device.
``IFF_UP``
Start the device.
``IFF_UP|IFF_RUNNING``
Stop then start the device.
``0``
Do nothing.
Write the Driver Statistic-Printing Function
============================================
This function should print the values of any statistic/diagnostic
counters the network driver may use. The driver ioctl function should call
the statistic-printing function when the ioctl command is``SIO_RTEMS_SHOW_STATS``.
.. COMMENT: COPYRIGHT (c) 1988-2002.
.. COMMENT: On-Line Applications Research Corporation (OAR).
.. COMMENT: All rights reserved.
This function should print the values of any statistic/diagnostic counters the
network driver may use. The driver ioctl function should call the
statistic-printing function when the ioctl command is ``SIO_RTEMS_SHOW_STATS``.

211
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@ -1,12 +1,16 @@
.. comment SPDX-License-Identifier: CC-BY-SA-4.0
.. COMMENT: Written by Eric Norum
.. COMMENT: COPYRIGHT (c) 1988-2002.
.. COMMENT: On-Line Applications Research Corporation (OAR).
.. COMMENT: All rights reserved.
Non-Volatile Memory Driver
##########################
The Non-Volatile driver is responsible for providing an
interface to various types of non-volatile memory. These
types of memory include, but are not limited to, Flash, EEPROM,
and battery backed RAM. The capabilities provided
The Non-Volatile driver is responsible for providing an interface to various
types of non-volatile memory. These types of memory include, but are not
limited to, Flash, EEPROM, and battery backed RAM. The capabilities provided
by this class of device driver are:
- Initialize the Non-Volatile Memory Driver
@ -23,72 +27,66 @@ by this class of device driver are:
- Erase the Non-Volatile Memory Area
There is currently only one non-volatile device driver included in the
RTEMS source tree. The information provided in this chapter
is based on drivers developed for applications using RTEMS.
It is hoped that this driver model information can form the
basis for a standard non-volatile memory driver model that
can be supported in future RTEMS distribution.
There is currently only one non-volatile device driver included in the RTEMS
source tree. The information provided in this chapter is based on drivers
developed for applications using RTEMS. It is hoped that this driver model
information can form the basis for a standard non-volatile memory driver model
that can be supported in future RTEMS distribution.
Major and Minor Numbers
=======================
The *major* number of a device driver is its index in the
RTEMS Device Address Table.
The ``major`` number of a device driver is its index in the RTEMS Device
Address Table.
A *minor* number is associated with each device instance
managed by a particular device driver. An RTEMS minor number
is an ``unsigned32`` entity. Convention calls
dividing the bits in the minor number down into categories
that specify an area of non-volatile memory and a partition
with that area. This results in categories
like the following:
A ``minor`` number is associated with each device instance managed by a
particular device driver. An RTEMS minor number is an ``unsigned32`` entity.
Convention calls dividing the bits in the minor number down into categories
that specify an area of non-volatile memory and a partition with that area.
This results in categories like the following:
- *area* - indicates a block of non-volatile memory
- ``area`` - indicates a block of non-volatile memory
- *partition* - indicates a particular address range with an area
- ``partition`` - indicates a particular address range with an area
From the above, it should be clear that a single device driver
can support multiple types of non-volatile memory in a single system.
The minor number is used to distinguish the types of memory and
blocks of memory used for different purposes.
From the above, it should be clear that a single device driver can support
multiple types of non-volatile memory in a single system. The minor number is
used to distinguish the types of memory and blocks of memory used for different
purposes.
Non-Volatile Memory Driver Configuration
========================================
There is not a standard non-volatile driver configuration table but some
fields are common across different drivers. The non-volatile memory driver
configuration table is typically an array of structures with each
structure containing the information for a particular area of
non-volatile memory.
The following is a list of the type of information normally required
to configure each area of non-volatile memory.
There is not a standard non-volatile driver configuration table but some fields
are common across different drivers. The non-volatile memory driver
configuration table is typically an array of structures with each structure
containing the information for a particular area of non-volatile memory. The
following is a list of the type of information normally required to configure
each area of non-volatile memory.
*memory_type*
``memory_type``
is the type of memory device in this area. Choices are battery backed RAM,
EEPROM, Flash, or an optional user-supplied type. If the user-supplied type
is configured, then the user is responsible for providing a set of
EEPROM, Flash, or an optional user-supplied type. If the user-supplied
type is configured, then the user is responsible for providing a set of
routines to program the memory.
*memory*
``memory``
is the base address of this memory area.
*attributes*
is a pointer to a memory type specific attribute block. Some of
the fields commonly contained in this memory type specific attribute
structure area:
*use_protection_algorithm*
``attributes``
is a pointer to a memory type specific attribute block. Some of the fields
commonly contained in this memory type specific attribute structure area:
``use_protection_algorithm``
is set to TRUE to indicate that the protection (i.e. locking) algorithm
should be used for this area of non-volatile memory. A particular
type of non-volatile memory may not have a protection algorithm.
*access*
should be used for this area of non-volatile memory. A particular type
of non-volatile memory may not have a protection algorithm.
``access``
is an enumerated type to indicate the organization of the memory
devices in this memory area. The following is a list of the
access types supported by the current driver implementation:
devices in this memory area. The following is a list of the access
types supported by the current driver implementation:
- simple unsigned8
- simple unsigned16
- simple unsigned32
@ -100,53 +98,48 @@ to configure each area of non-volatile memory.
- single unsigned8 at offset 2 in an unsigned32
- single unsigned8 at offset 3 in an unsigned32
*depth*
``depth``
is the depth of the progamming FIFO on this particular chip. Some
chips, particularly EEPROMs, have the same programming algorithm but
vary in the depth of the amount of data that can be programmed in a single
block.
vary in the depth of the amount of data that can be programmed in a
single block.
*number_of_partitions*
``number_of_partitions``
is the number of logical partitions within this area.
*Partitions*
``Partitions``
is the address of the table that contains an entry to describe each
partition in this area. Fields within each element of this
table are defined as follows:
*offset*
partition in this area. Fields within each element of this table are
defined as follows:
``offset``
is the offset of this partition from the base address of this area.
*length*
``length``
is the length of this partition.
By dividing an area of memory into multiple partitions, it is possible
to easily divide the non-volatile memory for different purposes.
By dividing an area of memory into multiple partitions, it is possible to
easily divide the non-volatile memory for different purposes.
Initialize the Non-Volatile Memory Driver
=========================================
At system initialization, the non-volatile memory driver's
initialization entry point will be invoked. As part of
initialization, the driver will perform
At system initialization, the non-volatile memory driver's initialization entry
point will be invoked. As part of initialization, the driver will perform
whatever initializatin is required on each non-volatile memory area.
The discrete I/O driver may register device names for memory
partitions of particular interest to the system. Normally this
will be restricted to the device "/dev/nv_memory" to indicate
the entire device driver.
The discrete I/O driver may register device names for memory partitions of
particular interest to the system. Normally this will be restricted to the
device "/dev/nv_memory" to indicate the entire device driver.
Disable Read and Write Handlers
===============================
Depending on the target's non-volatile memory configuration, it may be
possible to write to a status register and make the memory area completely
inaccessible. This is target dependent and beyond the standard capabilities
of any memory type. The user has the optional capability to provide
handlers to disable and enable access to a partiticular memory area.
Depending on the target's non-volatile memory configuration, it may be possible
to write to a status register and make the memory area completely inaccessible.
This is target dependent and beyond the standard capabilities of any memory
type. The user has the optional capability to provide handlers to disable and
enable access to a partiticular memory area.
Open a Particular Memory Partition
==================================
@ -155,8 +148,8 @@ This is the driver open call. Usually this call does nothing other than
validate the minor number.
With some drivers, it may be necessary to allocate memory when a particular
device is opened. If that is the case, then this is often the place
to do this operation.
device is opened. If that is the case, then this is often the place to do this
operation.
Close a Particular Memory Partition
===================================
@ -164,30 +157,29 @@ Close a Particular Memory Partition
This is the driver close call. Usually this call does nothing.
With some drivers, it may be necessary to allocate memory when a particular
device is opened. If that is the case, then this is the place
where that memory should be deallocated.
device is opened. If that is the case, then this is the place where that
memory should be deallocated.
Read from a Particular Memory Partition
=======================================
This corresponds to the driver read call. After validating the minor
number and arguments, this call enables reads from the specified
memory area by invoking the user supplied "enable reads handler"
and then reads the indicated memory area. When
invoked the ``argument_block`` is actually a pointer to the following
structure type:
.. code:: c
This corresponds to the driver read call. After validating the minor number
and arguments, this call enables reads from the specified memory area by
invoking the user supplied "enable reads handler" and then reads the indicated
memory area. When invoked the ``argument_block`` is actually a pointer to the
following structure type:
.. code-block:: c
typedef struct {
uint32_t offset;
void \*buffer;
void *buffer;
uint32_t length;
uint32_t status;
} Non_volatile_memory_Driver_arguments;
The driver reads ``length`` bytes starting at ``offset`` into
the partition and places them at ``buffer``. The result is returned
in ``status``.
The driver reads ``length`` bytes starting at ``offset`` into the partition and
places them at ``buffer``. The result is returned in ``status``.
After the read operation is complete, the user supplied "disable reads handler"
is invoked to protect the memory area again.
@ -195,40 +187,31 @@ is invoked to protect the memory area again.
Write to a Particular Memory Partition
======================================
This corresponds to the driver write call. After validating the minor
number and arguments, this call enables writes to the specified
memory area by invoking the "enable writes handler", then unprotecting
the memory area, and finally actually writing to the indicated memory
area. When invoked the ``argument_block`` is actually a pointer to
the following structure type:
.. code:: c
This corresponds to the driver write call. After validating the minor number
and arguments, this call enables writes to the specified memory area by
invoking the "enable writes handler", then unprotecting the memory area, and
finally actually writing to the indicated memory area. When invoked the
``argument_block`` is actually a pointer to the following structure type:
.. code-block:: c
typedef struct {
uint32_t offset;
void \*buffer;
void *buffer;
uint32_t length;
uint32_t status;
} Non_volatile_memory_Driver_arguments;
The driver writes ``length`` bytes from ``buffer`` and
writes them to the non-volatile memory starting at ``offset`` into
the partition. The result is returned in ``status``.
The driver writes ``length`` bytes from ``buffer`` and writes them to the
non-volatile memory starting at ``offset`` into the partition. The result is
returned in ``status``.
After the write operation is complete, the "disable writes handler"
is invoked to protect the memory area again.
After the write operation is complete, the "disable writes handler" is invoked
to protect the memory area again.
Erase the Non-Volatile Memory Area
==================================
This is one of the IOCTL functions supported by the I/O control
device driver entry point. When this IOCTL function is invoked,
the specified area of non-volatile memory is erased.
.. COMMENT: Written by Eric Norum
.. COMMENT: COPYRIGHT (c) 1988-2002.
.. COMMENT: On-Line Applications Research Corporation (OAR).
.. COMMENT: All rights reserved.
This is one of the IOCTL functions supported by the I/O control device driver
entry point. When this IOCTL function is invoked, the specified area of
non-volatile memory is erased.

24
bsp_howto/preface.rst
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@ -1,13 +1,17 @@
.. comment SPDX-License-Identifier: CC-BY-SA-4.0
.. COMMENT: COPYRIGHT (c) 1988-2002.
.. COMMENT: On-Line Applications Research Corporation (OAR).
.. COMMENT: All rights reserved.
Introduction
############
Before reading this documentation, it is strongly advised to read the
RTEMS Development Environment Guide to get acquainted with the RTEMS
directory structure. This document describes how to do a RTEMS Board
Support Package, i.e. how to port RTEMS on a new target board. Discussions
are provided for the following topics:
Before reading this documentation, it is strongly advised to read the RTEMS
Development Environment Guide to get acquainted with the RTEMS directory
structure. This document describes how to do a RTEMS Board Support Package,
i.e. how to port RTEMS on a new target board. Discussions are provided for the
following topics:
- RTEMS Board Support Package Organization
@ -15,7 +19,8 @@ are provided for the following topics:
- Board Initialization Sequence
- Device Drivers Including:
- Device Drivers:
- Console Driver
- Clock Driver
- Timer Driver
@ -51,10 +56,3 @@ So in this guide we will try to point out good examples from other BSPs.
Our goal is for you to be able to reuse as much code as possible and
write as little board specific code as possible.
.. COMMENT: COPYRIGHT (c) 1988-2002.
.. COMMENT: On-Line Applications Research Corporation (OAR).
.. COMMENT: All rights reserved.

157
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@ -1,14 +1,17 @@
.. comment SPDX-License-Identifier: CC-BY-SA-4.0
.. COMMENT: COPYRIGHT (c) 1988-2002.
.. COMMENT: On-Line Applications Research Corporation (OAR).
.. COMMENT: All rights reserved.
Real-Time Clock Driver
######################
Introduction
============
The Real-Time Clock (*RTC*) driver is responsible for providing an
interface to an *RTC* device. \[NOTE: In this chapter, the abbreviation*TOD* is used for *Time of Day*.] The capabilities provided by this
driver are:
The Real-Time Clock (*RTC*) driver is responsible for providing an interface to
an *RTC* device. The capabilities provided by this driver are:
- Set the RTC TOD to RTEMS TOD
@ -20,47 +23,53 @@ driver are:
- Get the Difference Between the RTEMS and RTC TOD
The reference implementation for a real-time clock driver can
be found in ``c/src/lib/libbsp/shared/tod.c``. This driver
is based on the libchip concept and can be easily configured
to work with any of the RTC chips supported by the RTC
chip drivers in the directory ``c/src/lib/lib/libchip/rtc``.
There is a README file in this directory for each supported
RTC chip. Each of these README explains how to configure the
shared libchip implementation of the RTC driver for that particular
RTC chip.
.. note::
In this chapter, the abbreviation `TOD` is used for *Time of Day*.
The reference implementation for a real-time clock driver can be found in
``c/src/lib/libbsp/shared/tod.c``. This driver is based on the libchip concept
and can be easily configured to work with any of the RTC chips supported by the
RTC chip drivers in the directory ``c/src/lib/lib/libchip/rtc``. There is a
README file in this directory for each supported RTC chip. Each of these
README explains how to configure the shared libchip implementation of the RTC
driver for that particular RTC chip.
The DY-4 DMV177 BSP used the shared libchip implementation of the RTC driver.
There were no DMV177 specific configuration routines. A BSP could use
configuration routines to dynamically determine what type of real-time clock is
on a particular board. This would be useful for a BSP supporting multiple
board models. The relevant ports of the DMV177's ``RTC_Table`` configuration
table is below:
The DY-4 DMV177 BSP used the shared libchip implementation of the RTC
driver. There were no DMV177 specific configuration routines. A BSP
could use configuration routines to dynamically determine what type
of real-time clock is on a particular board. This would be useful for
a BSP supporting multiple board models. The relevant ports of
the DMV177's ``RTC_Table`` configuration table is below:
.. code:: c
#include <bsp.h>
#include <libchip/rtc.h>
#include <libchip/icm7170.h>
bool dmv177_icm7170_probe(int minor);
rtc_tbl RTC_Table[] = {
{ "/dev/rtc0", /* sDeviceName \*/
RTC_ICM7170, /* deviceType \*/
&icm7170_fns, /* pDeviceFns \*/
dmv177_icm7170_probe, /* deviceProbe \*/
(void \*) ICM7170_AT_1_MHZ, /* pDeviceParams \*/
DMV170_RTC_ADDRESS, /* ulCtrlPort1 \*/
0, /* ulDataPort \*/
icm7170_get_register_8, /* getRegister \*/
icm7170_set_register_8, /* setRegister \*/
{ "/dev/rtc0", /* sDeviceName */
RTC_ICM7170, /* deviceType */
&icm7170_fns, /* pDeviceFns */
dmv177_icm7170_probe, /* deviceProbe */
(void *) ICM7170_AT_1_MHZ, /* pDeviceParams */
DMV170_RTC_ADDRESS, /* ulCtrlPort1 */
0, /* ulDataPort */
icm7170_get_register_8, /* getRegister */
icm7170_set_register_8, /* setRegister */
}
};
unsigned long RTC_Count = (sizeof(RTC_Table)/sizeof(rtc_tbl));
rtems_device_minor_number RTC_Minor;
bool dmv177_icm7170_probe(int minor)
{
volatile unsigned16 \*card_resource_reg;
card_resource_reg = (volatile unsigned16 \*) DMV170_CARD_RESORCE_REG;
if ( (\*card_resource_reg & DMV170_RTC_INST_MASK) == DMV170_RTC_INSTALLED )
volatile unsigned16 *card_resource_reg;
card_resource_reg = (volatile unsigned16 *) DMV170_CARD_RESORCE_REG;
if ( (*card_resource_reg & DMV170_RTC_INST_MASK) == DMV170_RTC_INSTALLED )
return TRUE;
return FALSE;
}
@ -68,23 +77,23 @@ the DMV177's ``RTC_Table`` configuration table is below:
Initialization
==============
The ``rtc_initialize`` routine is responsible for initializing the
RTC chip so it can be used. The shared libchip implementation of this
driver supports multiple RTCs and bases its initialization order on
the order the chips are defined in the ``RTC_Table``. Each chip
defined in the table may or may not be present on this particular board.
It is the responsibility of the ``deviceProbe`` to indicate the
presence of a particular RTC chip. The first RTC found to be present
is considered the preferred RTC.
The ``rtc_initialize`` routine is responsible for initializing the RTC chip so
it can be used. The shared libchip implementation of this driver supports
multiple RTCs and bases its initialization order on the order the chips are
defined in the ``RTC_Table``. Each chip defined in the table may or may not be
present on this particular board. It is the responsibility of the
``deviceProbe`` to indicate the presence of a particular RTC chip. The first
RTC found to be present is considered the preferred RTC.
In the shared libchip based implementation
of the driver, the following actions are performed:
.. code:: c
In the shared libchip based implementation of the driver, the following actions
are performed:
.. code-block:: c
rtems_device_driver rtc_initialize(
rtems_device_major_number major,
rtems_device_minor_number minor_arg,
void \*arg
void *arg
)
{
for each RTC configured in RTC_Table
@ -92,39 +101,42 @@ of the driver, the following actions are performed:
set RTC_Minor to this device
set RTC_Present to TRUE
break out of this loop
if RTC_Present is not TRUE
return RTEMS_INVALID_NUMBER to indicate that no RTC is present
register this minor number as the "/dev/rtc"
perform the deviceInitialize routine for the preferred RTC chip
for RTCs past this one in the RTC_Table
if the deviceProbe for this RTC indicates it is present
perform the deviceInitialize routine for this RTC chip
register the configured name for this RTC
}
The ``deviceProbe`` routine returns TRUE if the device
configured by this entry in the ``RTC_Table`` is present.
This configuration scheme allows one to support multiple versions
of the same board with a single BSP. For example, if the first
generation of a board had Vendor A's RTC chip and the second
generation had Vendor B's RTC chip, RTC_Table could contain
information for both. The ``deviceProbe`` configured
for Vendor A's RTC chip would need to return TRUE if the
board was a first generation one. The ``deviceProbe``
routines are very board dependent and must be provided by
the BSP.
The ``deviceProbe`` routine returns TRUE if the device configured by this entry
in the ``RTC_Table`` is present. This configuration scheme allows one to
support multiple versions of the same board with a single BSP. For example, if
the first generation of a board had Vendor A's RTC chip and the second
generation had Vendor B's RTC chip, RTC_Table could contain information for
both. The ``deviceProbe`` configured for Vendor A's RTC chip would need to
return TRUE if the board was a first generation one. The ``deviceProbe``
routines are very board dependent and must be provided by the BSP.
setRealTimeToRTEMS
==================
The ``setRealTimeToRTEMS`` routine sets the current RTEMS TOD to that
of the preferred RTC.
.. code:: c
.. code-block:: c
void setRealTimeToRTEMS(void)
{
if no RTCs are present
return
invoke the deviceGetTime routine for the preferred RTC
set the RTEMS TOD using rtems_clock_set
}
@ -134,12 +146,14 @@ setRealTimeFromRTEMS
The ``setRealTimeFromRTEMS`` routine sets the preferred RTC TOD to the
current RTEMS TOD.
.. code:: c
.. code-block:: c
void setRealTimeFromRTEMS(void)
{
if no RTCs are present
return
obtain the RTEMS TOD using rtems_clock_get
invoke the deviceSetTime routine for the preferred RTC
}
@ -147,52 +161,51 @@ current RTEMS TOD.
getRealTime
===========
The ``getRealTime`` returns the preferred RTC TOD to the
caller.
.. code:: c
The ``getRealTime`` returns the preferred RTC TOD to the caller.
void getRealTime( rtems_time_of_day \*tod )
.. code-block:: c
void getRealTime( rtems_time_of_day *tod )
{
if no RTCs are present
return
invoke the deviceGetTime routine for the preferred RTC
}
setRealTime
===========
The ``setRealTime`` routine sets the preferred RTC TOD to the
TOD specified by the caller.
.. code:: c
The ``setRealTime`` routine sets the preferred RTC TOD to the TOD specified by
the caller.
void setRealTime( rtems_time_of_day \*tod )
.. code-block:: c
void setRealTime( rtems_time_of_day *tod )
{
if no RTCs are present
return
invoke the deviceSetTime routine for the preferred RTC
}
checkRealTime
=============
The ``checkRealTime`` routine returns the number of seconds
difference between the RTC TOD and the current RTEMS TOD.
The ``checkRealTime`` routine returns the number of seconds difference between
the RTC TOD and the current RTEMS TOD.
.. code:: c
int checkRealTime( void )
{
if no RTCs are present
return -1
obtain the RTEMS TOD using rtems_clock_get
get the TOD from the preferred RTC using the deviceGetTime routine
convert the RTEMS TOD to seconds
convert the RTC TOD to seconds
return the RTEMS TOD in seconds - RTC TOD in seconds
}
.. COMMENT: COPYRIGHT (c) 1988-2002.
.. COMMENT: On-Line Applications Research Corporation (OAR).
.. COMMENT: All rights reserved.

226
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@ -1,86 +1,85 @@
.. comment SPDX-License-Identifier: CC-BY-SA-4.0
.. COMMENT: COPYRIGHT (c) 1988-2009.
.. COMMENT: On-Line Applications Research Corporation (OAR).
.. COMMENT: All rights reserved.
Shared Memory Support Driver
############################
The Shared Memory Support Driver is responsible for providing glue
routines and configuration information required by the Shared
Memory Multiprocessor Communications Interface (MPCI). The
Shared Memory Support Driver tailors the portable Shared
Memory Driver to a particular target platform.
The Shared Memory Support Driver is responsible for providing glue routines and
configuration information required by the Shared Memory Multiprocessor
Communications Interface (MPCI). The Shared Memory Support Driver tailors the
portable Shared Memory Driver to a particular target platform.
This driver is only required in shared memory multiprocessing
systems that use the RTEMS mulitprocessing support. For more
information on RTEMS multiprocessing capabilities and the
MPCI, refer to the *Multiprocessing Manager* chapter
of the *RTEMS Application C User's Guide*.
This driver is only required in shared memory multiprocessing systems that use
the RTEMS mulitprocessing support. For more information on RTEMS
multiprocessing capabilities and the MPCI, refer to the *Multiprocessing
Manager* chapter of the *RTEMS Application C User's Guide*.
Shared Memory Configuration Table
=================================
The Shared Memory Configuration Table is defined in the following
structure:
.. code:: c
The Shared Memory Configuration Table is defined in the following structure:
.. code-block:: c
typedef volatile uint32_t vol_u32;
typedef struct {
vol_u32 \*address; /* write here for interrupt \*/
vol_u32 value; /* this value causes interrupt \*/
vol_u32 length; /* for this length (0,1,2,4) \*/
vol_u32 *address; /* write here for interrupt */
vol_u32 value; /* this value causes interrupt */
vol_u32 length; /* for this length (0,1,2,4) */
} Shm_Interrupt_information;
struct shm_config_info {
vol_u32 \*base; /* base address of SHM \*/
vol_u32 length; /* length (in bytes) of SHM \*/
vol_u32 format; /* SHM is big or little endian \*/
vol_u32 (\*convert)(); /* neutral conversion routine \*/
vol_u32 poll_intr; /* POLLED or INTR driven mode \*/
void (\*cause_intr)( uint32_t );
Shm_Interrupt_information Intr; /* cause intr information \*/
vol_u32 *base; /* base address of SHM */
vol_u32 length; /* length (in bytes) of SHM */
vol_u32 format; /* SHM is big or little endian */
vol_u32 (*convert)(); /* neutral conversion routine */
vol_u32 poll_intr; /* POLLED or INTR driven mode */
void (*cause_intr)( uint32_t );
Shm_Interrupt_information Intr; /* cause intr information */
};
typedef struct shm_config_info shm_config_table;
where the fields are defined as follows:
*base*
is the base address of the shared memory buffer used to pass
messages between the nodes in the system.
``base``
is the base address of the shared memory buffer used to pass messages
between the nodes in the system.
*length*
is the length (in bytes) of the shared memory buffer used to pass
messages between the nodes in the system.
``length``
is the length (in bytes) of the shared memory buffer used to pass messages
between the nodes in the system.
*format*
is either SHM_BIG or SHM_LITTLE to indicate that the neutral format
of the shared memory area is big or little endian. The format
of the memory should be chosen to match most of the inter-node traffic.
``format``
is either ``SHM_BIG`` or ``SHM_LITTLE`` to indicate that the neutral format
of the shared memory area is big or little endian. The format of the
memory should be chosen to match most of the inter-node traffic.
*convert*
is the address of a routine which converts from native format to
neutral format. Ideally, the neutral format is the same as the
native format so this routine is quite simple.
``convert``
is the address of a routine which converts from native format to neutral
format. Ideally, the neutral format is the same as the native format so
this routine is quite simple.
*poll_intr*
is either INTR_MODE or POLLED_MODE to indicate how the node will be
``poll_intr``, ``cause_intr``
is either ``INTR_MODE`` or ``POLLED_MODE`` to indicate how the node will be
informed of incoming messages.
*cause_intr*
*Intr*
``Intr``
is the information required to cause an interrupt on a node. This
structure contains the following fields:
*address*
is the address to write at to cause an interrupt on that node.
For a polled node, this should be NULL.
*value*
``address``
is the address to write at to cause an interrupt on that node. For a
polled node, this should be NULL.
``value``
is the value to write to cause an interrupt.
*length*
``length``
is the length of the entity to write on the node to cause an interrupt.
This can be 0 to indicate polled operation, 1 to write a byte, 2 to
write a sixteen-bit entity, and 4 to write a thirty-two bit entity.
@ -91,16 +90,16 @@ Primitives
Convert Address
---------------
The ``Shm_Convert_address`` is responsible for converting an address
of an entity in the shared memory area into the address that should be
used from this node. Most targets will simply return the address
passed to this routine. However, some target boards will have a special
window onto the shared memory. For example, some VMEbus boards have
special address windows to access addresses that are normally reserved
in the CPU's address space.
.. code:: c
The ``Shm_Convert_address`` is responsible for converting an address of an
entity in the shared memory area into the address that should be used from this
node. Most targets will simply return the address passed to this routine.
However, some target boards will have a special window onto the shared memory.
For example, some VMEbus boards have special address windows to access
addresses that are normally reserved in the CPU's address space.
void \*Shm_Convert_address( void \*address )
.. code-block:: c
void *Shm_Convert_address( void *address )
{
return the local address version of this bus address
}
@ -108,13 +107,14 @@ in the CPU's address space.
Get Configuration
-----------------
The ``Shm_Get_configuration`` routine is responsible for filling in the
Shared Memory Configuration Table passed to it.
.. code:: c
The ``Shm_Get_configuration`` routine is responsible for filling in the Shared
Memory Configuration Table passed to it.
.. code-block:: c
void Shm_Get_configuration(
uint32_t localnode,
shm_config_table \**shmcfg
shm_config_table **shmcfg
)
{
fill in the Shared Memory Configuration Table
@ -123,53 +123,54 @@ Shared Memory Configuration Table passed to it.
Locking Primitives
------------------
This is a collection of routines that are invoked by the portable
part of the Shared Memory Driver to manage locks in the shared
memory buffer area. Accesses to the shared memory must be
atomic. Two nodes in a multiprocessor system must not be manipulating
the shared data structures simultaneously. The locking primitives
are used to insure this.
This is a collection of routines that are invoked by the portable part of the
Shared Memory Driver to manage locks in the shared memory buffer area.
Accesses to the shared memory must be atomic. Two nodes in a multiprocessor
system must not be manipulating the shared data structures simultaneously. The
locking primitives are used to insure this.
To avoid deadlock, local processor interrupts should be disabled the entire
time the locked queue is locked.
The locking primitives operate on the lock``field`` of the ``Shm_Locked_queue_Control``
data structure. This structure is defined as follows:
.. code:: c
The locking primitives operate on the lock ``field`` of the
``Shm_Locked_queue_Control`` data structure. This structure is defined as
follows:
.. code-block:: c
typedef struct {
vol_u32 lock; /* lock field for this queue \*/
vol_u32 front; /* first envelope on queue \*/
vol_u32 rear; /* last envelope on queue \*/
vol_u32 owner; /* receiving (i.e. owning) node \*/
vol_u32 lock; /* lock field for this queue */
vol_u32 front; /* first envelope on queue */
vol_u32 rear; /* last envelope on queue */
vol_u32 owner; /* receiving (i.e. owning) node */
} Shm_Locked_queue_Control;
where each field is defined as follows:
*lock*
is the lock field. Every node in the system must agree on how this
field will be used. Many processor families provide an atomic
"test and set" instruction that is used to manage this field.
``lock``
is the lock field. Every node in the system must agree on how this field
will be used. Many processor families provide an atomic "test and set"
instruction that is used to manage this field.
*front*
``front``
is the index of the first message on this locked queue.
*rear*
``rear``
is the index of the last message on this locked queue.
*owner*
``owner``
is the node number of the node that currently has this structure locked.
Initializing a Shared Lock
~~~~~~~~~~~~~~~~~~~~~~~~~~
The ``Shm_Initialize_lock`` routine is responsible for
initializing the lock field. This routines usually is implemented
as follows:
.. code:: c
The ``Shm_Initialize_lock`` routine is responsible for initializing the lock
field. This routines usually is implemented as follows:
.. code-block:: c
void Shm_Initialize_lock(
Shm_Locked_queue_Control \*lq_cb
Shm_Locked_queue_Control *lq_cb
)
{
lq_cb->lock = LQ_UNLOCKED;
@ -178,21 +179,21 @@ as follows:
Acquiring a Shared Lock
~~~~~~~~~~~~~~~~~~~~~~~
The ``Shm_Lock`` routine is responsible for
acquiring the lock field. Interrupts should be
disabled while that lock is acquired. If the lock
is currently unavailble, then the locking routine
should delay a few microseconds to allow the other
node to release the lock. Doing this reduces bus contention
The ``Shm_Lock`` routine is responsible for acquiring the lock field.
Interrupts should be disabled while that lock is acquired. If the lock is
currently unavailble, then the locking routine should delay a few microseconds
to allow the other node to release the lock. Doing this reduces bus contention
for the lock. This routines usually is implemented as follows:
.. code:: c
.. code-block:: c
void Shm_Lock(
Shm_Locked_queue_Control \*lq_cb
Shm_Locked_queue_Control *lq_cb
)
{
disable processor interrupts
set Shm_isrstat to previous interrupt disable level
while ( TRUE ) {
atomically attempt to acquire the lock
if the lock was acquired
@ -204,13 +205,14 @@ for the lock. This routines usually is implemented as follows:
Releasing a Shared Lock
~~~~~~~~~~~~~~~~~~~~~~~
The ``Shm_Unlock`` routine is responsible for
releasing the lock field and reenabling processor
interrupts. This routines usually is implemented as follows:
.. code:: c
The ``Shm_Unlock`` routine is responsible for releasing the lock field and
reenabling processor interrupts. This routines usually is implemented as
follows:
.. code-block:: c
void Shm_Unlock(
Shm_Locked_queue_Control \*lq_cb
Shm_Locked_queue_Control *lq_cb
)
{
set the lock to the unlocked value
@ -222,16 +224,15 @@ interrupts. This routines usually is implemented as follows:
Installing the MPCI ISR
=======================
The ``Shm_setvec`` is invoked by the portable portion
of the shared memory to install the interrupt service routine
that is invoked when an incoming message is announced. Some
target boards support an interprocessor interrupt or mailbox
scheme and this is where the ISR for that interrupt would be
installed.
The ``Shm_setvec`` is invoked by the portable portion of the shared memory to
install the interrupt service routine that is invoked when an incoming message
is announced. Some target boards support an interprocessor interrupt or
mailbox scheme and this is where the ISR for that interrupt would be installed.
On an interrupt driven node, this routine would be implemented
as follows:
.. code:: c
.. code-block:: c
void Shm_setvec( void )
{
@ -239,10 +240,3 @@ as follows:
}
On a polled node, this routine would be empty.
.. COMMENT: COPYRIGHT (c) 1988-2009.
.. COMMENT: On-Line Applications Research Corporation (OAR).
.. COMMENT: All rights reserved.

259
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@ -1,14 +1,18 @@
.. comment SPDX-License-Identifier: CC-BY-SA-4.0
.. COMMENT: COPYRIGHT (c) 1988-2008.
.. COMMENT: On-Line Applications Research Corporation (OAR).
.. COMMENT: All rights reserved.
Target Dependent Files
######################
RTEMS has a multi-layered approach to portability. This is done to
maximize the amount of software that can be reused. Much of the
RTEMS source code can be reused on all RTEMS platforms. Other parts
of the executive are specific to hardware in some sense.
RTEMS classifies target dependent code based upon its dependencies
into one of the following categories.
RTEMS has a multi-layered approach to portability. This is done to maximize the
amount of software that can be reused. Much of the RTEMS source code can be
reused on all RTEMS platforms. Other parts of the executive are specific to
hardware in some sense. RTEMS classifies target dependent code based upon its
dependencies into one of the following categories.
- CPU dependent
@ -19,70 +23,68 @@ into one of the following categories.
CPU Dependent
=============
This class of code includes the foundation
routines for the executive proper such as the context switch and
the interrupt subroutine implementations. Sources for the supported
processor families can be found in ``cpukit/score/cpu``.
A good starting point for a new family of processors is the``no_cpu`` directory, which holds both prototypes and
descriptions of each needed CPU dependent function.
This class of code includes the foundation routines for the executive proper
such as the context switch and the interrupt subroutine implementations.
Sources for the supported processor families can be found in
``cpukit/score/cpu``. A good starting point for a new family of processors is
the ``no_cpu`` directory, which holds both prototypes and descriptions of each
needed CPU dependent function.
CPU dependent code is further subcategorized if the implementation is
dependent on a particular CPU model. For example, the MC68000 and MC68020
processors are both members of the m68k CPU family but there are significant
differences between these CPU models which RTEMS must take into account.
CPU dependent code is further subcategorized if the implementation is dependent
on a particular CPU model. For example, the MC68000 and MC68020 processors are
both members of the m68k CPU family but there are significant differences
between these CPU models which RTEMS must take into account.
The source code found in the ``cpukit/score/cpu`` is required to
only depend upon the CPU model variations that GCC distinguishes
for the purposes of multilib'ing. Multilib is the term the GNU
community uses to refer to building a single library source multiple
times with different compiler options so the binary code generated
is compatible. As an example, from GCC's perspective, many PowerPC
CPU models are just a PPC603e. Remember that GCC only cares about
the CPU code itself and need not be aware of any peripherals. In
the embedded community, we are exposed to thousands of CPU models
which are all based upon only a relative small number of CPU cores.
The source code found in the ``cpukit/score/cpu`` is required to only depend
upon the CPU model variations that GCC distinguishes for the purposes of
multilib'ing. Multilib is the term the GNU community uses to refer to building
a single library source multiple times with different compiler options so the
binary code generated is compatible. As an example, from GCC's perspective,
many PowerPC CPU models are just a PPC603e. Remember that GCC only cares about
the CPU code itself and need not be aware of any peripherals. In the embedded
community, we are exposed to thousands of CPU models which are all based upon
only a relative small number of CPU cores.
Similarly for the SPARC/ERC32 BSP, the ``RTEMS_CPU`` is specified as``erc32`` which is the name of the CPU model and BSP for this SPARC V7
system on chip. But the multilib variant used is actually ``v7``
which indicates the ERC32 CPU core is a SPARC V7.
Similarly for the SPARC/ERC32 BSP, the ``RTEMS_CPU`` is specified as ``erc32``
which is the name of the CPU model and BSP for this SPARC V7 system on chip.
But the multilib variant used is actually ``v7`` which indicates the ERC32 CPU
core is a SPARC V7.
Board Dependent
===============
This class of code provides the most specific glue between RTEMS and
a particular board. This code is represented by the Board Support Packages
and associated Device Drivers. Sources for the BSPs included in the
RTEMS distribution are located in the directory ``c/src/lib/libbsp``.
The BSP source directory is further subdivided based on the CPU family
and BSP.
This class of code provides the most specific glue between RTEMS and a
particular board. This code is represented by the Board Support Packages and
associated Device Drivers. Sources for the BSPs included in the RTEMS
distribution are located in the directory ``c/src/lib/libbsp``. The BSP source
directory is further subdivided based on the CPU family and BSP.
Some BSPs may support multiple board models within a single board family.
This is necessary when the board supports multiple variants on a
single base board. For example, the Motorola MVME162 board family has a
fairly large number of variations based upon the particular CPU model
and the peripherals actually placed on the board.
Some BSPs may support multiple board models within a single board family. This
is necessary when the board supports multiple variants on a single base board.
For example, the Motorola MVME162 board family has a fairly large number of
variations based upon the particular CPU model and the peripherals actually
placed on the board.
Peripheral Dependent
====================
This class of code provides a reusable library of peripheral device
drivers which can be tailored easily to a particular board. The
libchip library is a collection of reusable software objects that
correspond to standard controllers. Just as the hardware engineer
chooses a standard controller when designing a board, the goal of
this library is to let the software engineer do the same thing.
This class of code provides a reusable library of peripheral device drivers
which can be tailored easily to a particular board. The libchip library is a
collection of reusable software objects that correspond to standard
controllers. Just as the hardware engineer chooses a standard controller when
designing a board, the goal of this library is to let the software engineer do
the same thing.
The source code for the reusable peripheral driver library may be found
in the directory ``c/src/lib/libchip``. The source code is further
divided based upon the class of hardware. Example classes include serial
communications controllers, real-time clocks, non-volatile memory, and
network controllers.
The source code for the reusable peripheral driver library may be found in the
directory ``c/src/lib/libchip``. The source code is further divided based upon
the class of hardware. Example classes include serial communications
controllers, real-time clocks, non-volatile memory, and network controllers.
Questions to Ask
================
When evaluating what is required to support RTEMS applications on
a particular target board, the following questions should be asked:
When evaluating what is required to support RTEMS applications on a particular
target board, the following questions should be asked:
- Does a BSP for this board exist?
@ -90,46 +92,47 @@ a particular target board, the following questions should be asked:
- Is the board's CPU supported?
If there is already a BSP for the board, then things may already be ready
to start developing application software. All that remains is to verify
that the existing BSP provides device drivers for all the peripherals
on the board that the application will be using. For example, the application
in question may require that the board's Ethernet controller be used and
the existing BSP may not support this.
If there is already a BSP for the board, then things may already be ready to
start developing application software. All that remains is to verify that the
existing BSP provides device drivers for all the peripherals on the board that
the application will be using. For example, the application in question may
require that the board's Ethernet controller be used and the existing BSP may
not support this.
If the BSP does not exist and the board's CPU model is supported, then
examine the reusable chip library and existing BSPs for a close match.
Other BSPs and libchip provide starting points for the development
of a new BSP. It is often possible to copy existing components in
the reusable chip library or device drivers from BSPs from different
CPU families as the starting point for a new device driver.
This will help reduce the development effort required.
If the BSP does not exist and the board's CPU model is supported, then examine
the reusable chip library and existing BSPs for a close match. Other BSPs and
libchip provide starting points for the development of a new BSP. It is often
possible to copy existing components in the reusable chip library or device
drivers from BSPs from different CPU families as the starting point for a new
device driver. This will help reduce the development effort required.
If the board's CPU family is supported but the particular CPU model on
that board is not, then the RTEMS port to that CPU family will have to
be augmented. After this is done, development of the new BSP can proceed.
If the board's CPU family is supported but the particular CPU model on that
board is not, then the RTEMS port to that CPU family will have to be augmented.
After this is done, development of the new BSP can proceed.
Otherwise both CPU dependent code and the BSP will have to be written.
This type of development often requires specialized skills. If
you need help in making these modifications to RTEMS, please
consider using one of the RTEMS Service Providers. The current
list of these is at http://www.rtems.org/support.html.
This type of development often requires specialized skills and there are people
in the community who provide those services. If you need help in making these
modifications to RTEMS try a search in a search engine with something like
"rtems support". The RTEMS Project encourages users to use support services
however we do not endorse any providers.
CPU Dependent Executive Files
=============================
The CPU dependent files in the RTEMS executive source code are found
in the following directory:
The CPU dependent files in the RTEMS executive source code are found in the
following directory:
.. code:: c
cpukit/score/cpu/*CPU*
cpukit/score/cpu/<CPU>
where *CPU* is replaced with the CPU family name.
where <CPU> is replaced with the CPU family name.
Within each CPU dependent directory inside the executive proper is a
file named ``*CPU*.h`` which contains information about each of the
supported CPU models within that family.
Within each CPU dependent directory inside the executive proper is a file named
``<CPU>.h`` which contains information about each of the supported CPU models
within that family.
CPU Dependent Support Files
===========================
@ -142,93 +145,85 @@ This class of code may be found in the following directory:
.. code:: c
c/src/lib/libcpu/*CPU*
c/src/lib/libcpu/<CPU>
CPU model dependent support code is found in the following directory:
.. code:: c
c/src/lib/libcpu/*CPU*/*CPU_MODEL*
c/src/lib/libcpu/<CPU>/<CPU_MODEL>
*CPU_MODEL* may be a specific CPU model name or a name indicating a CPU
core or a set of related CPU models. The file ``configure.ac`` in each ``c/src/lib/libcpu/*CPU*`` directory contains the logic which enables
the appropriate subdirectories for the specific CPU model your BSP has.
<CPU_MODEL> may be a specific CPU model name or a name indicating a CPU core or
a set of related CPU models. The file ``configure.ac`` in each
``c/src/lib/libcpu/<CPU>`` directory contains the logic which enables the
appropriate subdirectories for the specific CPU model your BSP has.
Board Support Package Structure
===============================
The BSPs are all under the ``c/src/lib/libbsp`` directory. Below this
directory, there is a subdirectory for each CPU family. Each BSP
is found under the subdirectory for the appropriate processor
family (m68k, powerpc, etc.). In addition, there is source code
available which may be shared across all BSPs regardless of
the CPU family or just across BSPs within a single CPU family. This
results in a BSP using the following directories:
directory, there is a subdirectory for each CPU family. Each BSP is found
under the subdirectory for the appropriate processor family (arm, powerpc,
sparc, etc.). In addition, there is source code available which may be shared
across all BSPs regardless of the CPU family or just across BSPs within a
single CPU family. This results in a BSP using the following directories:
.. code:: c
c/src/lib/libbsp/shared
c/src/lib/libbsp/*CPU*/shared
c/src/lib/libbsp/*CPU*/*BSP*
c/src/lib/libbsp/<CPU>/shared
c/src/lib/libbsp/<CPU>/<BSP>
Under each BSP specific directory, there is a collection of
subdirectories. For commonly provided functionality, the BSPs
follow a convention on subdirectory naming. The following list
describes the commonly found subdirectories under each BSP.
Under each BSP specific directory, there is a collection of subdirectories.
For commonly provided functionality, the BSPs follow a convention on
subdirectory naming. The following list describes the commonly found
subdirectories under each BSP.
- *console*:
is technically the serial driver for the BSP rather
than just a console driver, it deals with the board
UARTs (i.e. serial devices).
- ``console``:
is technically the serial driver for the BSP rather than just a console
driver, it deals with the board UARTs (i.e. serial devices).
- *clock*:
- ``clock``:
support for the clock tick - a regular time basis to the kernel.
- *timer*:
- ``timer``:
support of timer devices.
- *rtc* or ``tod``:
- ``rtc`` or ``tod``:
support for the hardware real-time clock.
- *nvmem*:
- ``nvmem``:
support for non-volatile memory such as EEPROM or Flash.
- *network*:
- ``network``:
the Ethernet driver.
- *shmsupp*:
- ``shmsupp``:
support of shared memory driver MPCI layer in a multiprocessor system,
- *include*:
- ``include``:
include files for this BSP.
- *gnatsupp*:
BSP specific support for the GNU Ada run-time. Each BSP that wishes
to have the possibility to map faults or exceptions into Ada language
exceptions or hardware interrupts into Ada interrupt tasks must provide
this support.
- ``gnatsupp``:
BSP specific support for the GNU Ada run-time. Each BSP that wishes to have
the possibility to map faults or exceptions into Ada language exceptions or
hardware interrupts into Ada interrupt tasks must provide this support.
There may be other directories in the BSP tree and the name should
be indicative of the functionality of the code within that directory.
There may be other directories in the BSP tree and the name should be
indicative of the functionality of the code within that directory.
The build order of the BSP is determined by the Makefile structure.
This structure is discussed in more detail in the `Makefiles`_
chapter.
The build order of the BSP is determined by the Makefile structure. This
structure is discussed in more detail in the `Makefiles`_ chapter.
.. sidebar:
This manual refers to the gen68340 BSP for numerous concrete examples. You
should have a copy of the gen68340 BSP available while reading this piece of
documentation. This BSP is located in the following directory:
*NOTE:* This manual refers to the gen68340 BSP for numerous concrete
examples. You should have a copy of the gen68340 BSP available while
reading this piece of documentation. This BSP is located in the
following directory:
.. code:: c
c/src/lib/libbsp/m68k/gen68340
Later in this document, the $BSP340_ROOT label will be used
to refer to this directory.
.. COMMENT: COPYRIGHT (c) 1988-2008.
.. COMMENT: On-Line Applications Research Corporation (OAR).
.. COMMENT: All rights reserved.
Later in this document, the $BSP340_ROOT label will be used to refer to this
directory.

100
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@ -1,35 +1,38 @@
.. comment SPDX-License-Identifier: CC-BY-SA-4.0
.. COMMENT: COPYRIGHT (c) 1988-2002.
.. COMMENT: On-Line Applications Research Corporation (OAR).
.. COMMENT: All rights reserved.
Timer Driver
############
The timer driver is primarily used by the RTEMS Timing Tests.
This driver provides as accurate a benchmark timer as possible.
It typically reports its time in microseconds, CPU cycles, or
bus cycles. This information can be very useful for determining
precisely what pieces of code require optimization and to measure the
impact of specific minor changes.
The timer driver is primarily used by the RTEMS Timing Tests. This driver
provides as accurate a benchmark timer as possible. It typically reports its
time in microseconds, CPU cycles, or bus cycles. This information can be very
useful for determining precisely what pieces of code require optimization and
to measure the impact of specific minor changes.
The gen68340 BSP also uses the Timer Driver to support a high performance
mode of the on-CPU UART.
The gen68340 BSP also uses the Timer Driver to support a high performance mode
of the on-CPU UART.
Benchmark Timer
===============
The RTEMS Timing Test Suite requires a benchmark timer. The
RTEMS Timing Test Suite is very helpful for determining
the performance of target hardware and comparing its performance
to that of other RTEMS targets.
The RTEMS Timing Test Suite requires a benchmark timer. The RTEMS Timing Test
Suite is very helpful for determining the performance of target hardware and
comparing its performance to that of other RTEMS targets.
This section describes the routines which are assumed to exist by
the RTEMS Timing Test Suite. The names used are *EXACTLY* what
is used in the RTEMS Timing Test Suite so follow the naming convention.
This section describes the routines which are assumed to exist by the RTEMS
Timing Test Suite. The names used are *EXACTLY* what is used in the RTEMS
Timing Test Suite so follow the naming convention.
benchmark_timer_initialize
--------------------------
Initialize the timer source.
.. code:: c
.. code-block:: c
void benchmark_timer_initialize(void)
{
@ -39,10 +42,11 @@ Initialize the timer source.
Read_timer
----------
The ``benchmark_timer_read`` routine returns the number of benchmark
time units (typically microseconds) that have elapsed since the last
call to ``benchmark_timer_initialize``.
.. code:: c
The ``benchmark_timer_read`` routine returns the number of benchmark time units
(typically microseconds) that have elapsed since the last call to
``benchmark_timer_initialize``.
.. code-block:: c
benchmark_timer_t benchmark_timer_read(void)
{
@ -52,23 +56,23 @@ call to ``benchmark_timer_initialize``.
return the stop time
}
Many implementations of this routine subtract the overhead required
to initialize and read the benchmark timer. This makes the times reported
more accurate.
Many implementations of this routine subtract the overhead required to
initialize and read the benchmark timer. This makes the times reported more
accurate.
Some implementations report 0 if the harware timer value change is
sufficiently small. This is intended to indicate that the execution time
is below the resolution of the timer.
Some implementations report 0 if the harware timer value change is sufficiently
small. This is intended to indicate that the execution time is below the
resolution of the timer.
benchmark_timer_disable_subtracting_average_overhead
----------------------------------------------------
This routine is invoked by the "Check Timer" (``tmck``) test in the
RTEMS Timing Test Suite. It makes the ``benchmark_timer_read``
routine NOT subtract the overhead required
to initialize and read the benchmark timer. This is used
by the ``tmoverhd`` test to determine the overhead
required to initialize and read the timer.
This routine is invoked by the "Check Timer" (``tmck``) test in the RTEMS
Timing Test Suite. It makes the ``benchmark_timer_read`` routine NOT subtract
the overhead required to initialize and read the benchmark timer. This is used
by the ``tmoverhd`` test to determine the overhead required to initialize and
read the timer.
.. code:: c
void benchmark_timer_disable_subtracting_average_overhead(bool find_flag)
@ -76,31 +80,23 @@ required to initialize and read the timer.
disable the subtract overhead feature
}
The ``benchmark_timer_find_average_overhead`` variable is used to
indicate the state of the "subtract overhead feature".
The ``benchmark_timer_find_average_overhead`` variable is used to indicate the
state of the "subtract overhead feature".
gen68340 UART FIFO Full Mode
============================
The gen68340 BSP is an example of the use of the timer to support the UART
input FIFO full mode (FIFO means First In First Out and roughly means
buffer). This mode consists in the UART raising an interrupt when n
characters have been received (*n* is the UART's FIFO length). It results
in a lower interrupt processing time, but the problem is that a scanf
primitive will block on a receipt of less than *n* characters. The solution
is to set a timer that will check whether there are some characters
waiting in the UART's input FIFO. The delay time has to be set carefully
otherwise high rates will be broken:
buffer). This mode consists in the UART raising an interrupt when n characters
have been received (*n* is the UART's FIFO length). It results in a lower
interrupt processing time, but the problem is that a scanf primitive will block
on a receipt of less than *n* characters. The solution is to set a timer that
will check whether there are some characters waiting in the UART's input
FIFO. The delay time has to be set carefully otherwise high rates will be
broken:
- if no character was received last time the interrupt subroutine was
entered, set a long delay,
- otherwise set the delay to the delay needed for *n* characters
receipt.
.. COMMENT: COPYRIGHT (c) 1988-2002.
.. COMMENT: On-Line Applications Research Corporation (OAR).
.. COMMENT: All rights reserved.
- if no character was received last time the interrupt subroutine was entered,
set a long delay,
- otherwise set the delay to the delay needed for ``n`` characters receipt.