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user/bsp/imxrt: Information for custom FDT

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Update #4180
This commit is contained in:
Christian Mauderer 2020-12-14 11:22:39 +01:00
parent 171bbe096f
commit 2cf3076320
1 changed files with 38 additions and 8 deletions
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46
user/bsps/arm/imxrt.rst
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@ -78,17 +78,47 @@ look at the `i.MX RT1050 Processor Reference Manual, Rev. 4, 12/2019` chapter
FDT
---
The BSP used a FDT based initialization. The FDT is linked into the application.
The BSP uses a FDT based initialization. The FDT is linked into the application.
You can find the default FDT used in the BSP in
`bsps/arm/imxrt/dts/imxrt1050-evkb.dts`. To use your own FDT compile it and
convert it into a C file with (replace `YOUR.dts` and simmilar with your FDT
source names)::
`bsps/arm/imxrt/dts/imxrt1050-evkb.dts`. The FDT is split up into two parts. The
core part is put into an `dtsi` file and is installed together with normal
headers into `${PREFIX}/arm-rtems6/imxrt1052/lib/include`. You can use that to
create your own device tree based on that. Basically use something like::
/dts-v1/;
#include <imxrt/imxrt1050-pinfunc.h>
#include <imxrt/imxrt1050.dtsi>
&lpuart1 {
pinctrl-0 = <&pinctrl_lpuart1>;
status = "okay";
};
&chosen {
stdout-path = &lpuart1;
};
/* put your further devices here */
&iomuxc {
pinctrl_lpuart1: lpuart1grp {
fsl,pins = <
IMXRT_PAD_GPIO_AD_B0_12__LPUART1_TX 0x8
IMXRT_PAD_GPIO_AD_B0_13__LPUART1_RX 0x13000
>;
};
/* put your further pinctrl groups here */
};
You can then convert your FDT into a C file with (replace `YOUR.dts` and similar
with your FDT source names)::
sh> export BSP_DIR="${RTEMS_SRC_DIR}/bsps/arm/imxrt/"
sh> arm-rtems6-cpp -P -x assembler-with-cpp \
-I "${BSP_DIR}/include/" \
-include "YOUR.dts" /dev/null | \
dtc -@ -O dtb -o "YOUR.dtb" -b 0 -p 1024
-I ${PREFIX}/arm-rtems6/imxrt1052/lib/include \
-include "YOUR.dts" /dev/null | \
dtc -@ -O dtb -o "YOUR.dtb" -b 0 -p 1024
sh> rtems-bin2c -C -N imxrt_dtb "YOUR.dtb" "YOUR.c"
Make sure that your new c file is compiled and linked into the application.