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user/bsps/arm/beagle: Update i2c initialization instructions

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The new i2c driver in the beagle BSP uses FDT based initialization.
This updates the documentation of the BSP about the same.
This commit is contained in:
G S Niteesh Babu 2021-04-11 00:45:25 +05:30 committed by Christian Mauderer
parent f6f3fdcd09
commit 2ce0fe2b8e
1 changed files with 28 additions and 13 deletions
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41
user/bsps/arm/beagle.rst
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@ -67,23 +67,38 @@ Add the following to a file named uEnv.txt:
I2C Driver
----------
The Beagle has the `i2c-0` device registered at initialization. For registering
`i2c-1` and `i2c-2` ``bbb_register_i2c_1()`` and
``bbb_register_i2c_2()`` wrapper functions are respectively used.
The Beagle i2c initialization is based on the device tree. To initialize a i2c
device, the user has to enable the respective node in the device tree using
overlays.
For registering an I2C device with a custom path (say `/dev/i2c-3`) the
function ``am335x_i2c_bus_register()`` has to be used.
For registering an I2C device with a custom path (say `/dev/i2c-eeprom`) an
overlay has to be provided. The overlay must add an additional attribute
`rtems,path` with the custom path as value to the respective i2c node.
The function prototype is given below:
For example,
.. code-block:: C
.. code-block::
/dts-v1/;
int am335x_i2c_bus_register(
const char *bus_path,
uintptr_t register_base,
uint32_t input_clock,
rtems_vector_number irq
);
/ {
compatible = "ti,am335x-bone-black", "ti,am335x-bone", "ti,am33xx";
fragment@0 {
target = <0xffffffff>;
__overlay__ {
compatible = "rtems,bsp-i2c", "ti,omap4-i2c";
status = "okay";
rtems,path = "/dev/i2c-eeprom";
};
};
__fixups__ {
i2c0 = "/fragment@0:target:0";
};
};
The above example registers a custom path `/dev/i2c-eeprom` for i2c0.
SPI Driver
----------