https://github.com/patsaoglou/mys-6ulx-iot-spidev-dts
Modified device tree for the MYS-6ULX-IOT dev board based on the IMX6ULL to enable SPIDEV
https://github.com/patsaoglou/mys-6ulx-iot-spidev-dts
device-tree embedded-linux imx6 linux spi spidev
Last synced: 3 months ago
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Modified device tree for the MYS-6ULX-IOT dev board based on the IMX6ULL to enable SPIDEV
- Host: GitHub
- URL: https://github.com/patsaoglou/mys-6ulx-iot-spidev-dts
- Owner: patsaoglou
- License: mit
- Created: 2025-03-30T11:27:40.000Z (6 months ago)
- Default Branch: main
- Last Pushed: 2025-03-30T11:41:36.000Z (6 months ago)
- Last Synced: 2025-07-01T07:07:21.706Z (3 months ago)
- Topics: device-tree, embedded-linux, imx6, linux, spi, spidev
- Homepage:
- Size: 13.7 KB
- Stars: 1
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# MYS-6ULX-IOT modified device trees
In this repository I share modified device tree from the preconfigured Linux source provided by MYIR Tech for the MYS-6ULX-IOT iMX6ULL based board to enable the SPI bus in order to use userspace SPIDEV under /dev/spidev0.*. I also disable some unnecessary stuff i don't use.
## Prerequisites
1. **Preconfigured Linux source:** available SDK provided by MYIR Tech under https://d.myirtech.com/MYS-6ULX/ - Sources
2. **SPI related linux drivers:** spi plattform related drivers for the IMX6 soc and spidev related stuff should be enabled within menuconfig and compiled as a module or built-in
## Compiling DTS
1. Navigate to the linux source root directory
2. Under the terminal run to preprocess the DTS:
```shell
cpp -nostdinc -I include -I arch -undef -x assembler-with-cpp arch/arm/boot/dts mys-6ull-14x14-gpmi-weim.dts mys-6ull-14x14-gpmi-weim.dts.preprocessed
```
3. Run to get the device tree blob:
```shell
dtc -I dts -O dtb -p 0x1000 mys-6ull-14x14-gpmi-weim.dts.preprocessed -o mys-6ull-14x14-gpmi-weim-modified.dtb
```
## Updating DTB under U-BOOT
1. Copy the modified DTB into the boot partition (in my config I boot from sdcard and the bootloader is running from the nand flash)
2. Set DTB environment variable, base address and load it to the bootloader:
```u-boot
setenv fdt_file mys-6ull-14x14-gpmi-weim-modified.dtb
setenv fdt_addr_r 0x83000000
load mmc 0:1 ${fdt_addr_r} ${fdt_file}
```
3. If you don't want to change anything else save u-boot configuration and you can boot:
```u-boot
saveenv
boot
```
4. Complete reconfiguration of the bootloader:
```u-boot
setenv fdt_file mys-6ull-14x14-gpmi-weim-modified.dtb
setenv fdt_addr_r 0x83000000
load mmc 0:1 ${fdt_addr_r} ${fdt_file}
load mmc 0:1 ${loadaddr} zImage
bootz ${loadaddr} - ${fdt_addr_r}
setenv bootcmd 'load mmc 0:1 ${loadaddr} zImage; load mmc 0:1 ${fdt_addr_r} ${fdt_file}; bootz ${loadaddr} - ${fdt_addr_r}'
saveenv
```
## Enabling SPI bus
- Setting 2 chipselect pins
- compatible is set to "rohm,dh2228fv" instead of "spidev" so there is no stack trace error at boot (dmesg)
- pin cs set to active logic 0 - as typical too
```dts
&ecspi1 {
fsl,spi-num-chipselects = <2>;
cs-gpios = <&gpio4 26 0>, <&gpio4 24 0>;
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_ecspi1 &pinctrl_ecspi1_cs>;
status = "okay";
spidev@0 {
compatible = "rohm,dh2228fv";
spi-max-frequency = <8000000>;
reg = <0>;
};
spidev@1 {
compatible = "rohm,dh2228fv";
spi-max-frequency = <8000000>;
reg = <1>;
};
};
```
## Assigning pins
```dts
pinctrl_ecspi1: ecspi1grp {
fsl,pins = <
MX6UL_PAD_CSI_DATA07__ECSPI1_MISO 0x100b1
MX6UL_PAD_CSI_DATA06__ECSPI1_MOSI 0x100b1
MX6UL_PAD_CSI_DATA04__ECSPI1_SCLK 0x100b1
>;
};
pinctrl_ecspi1_cs: ecspi1cs {
fsl,pins = <
MX6UL_PAD_CSI_DATA05__GPIO4_IO26 0x80000000 //CS0
MX6UL_PAD_CSI_DATA03__GPIO4_IO24 0x80000000 //CS1
>;
};
```
## Resources
Resolve stack trace: https://yurovsky.github.io/2016/10/07/spidev-linux-devices.html
Resolve dts compilation error with typical command: https://stackoverflow.com/questions/50658326/device-tree-compiler-not-recognizes-c-syntax-for-include-files
## Disclaimer
All other necessary files for the board were supplied by MYIR Tech SDK and I share the
modification to be available as a resource. Wish i had that when i did it.
Use it at your own responsibility.
If any mistakes let me know.