How to set GPIO initial setting for i.MX8M Mini.

[tan-k]

Hi,

We use custom board using i.MX8M Mini.
And we try to change OS based on Linux for i.MX (Linux 5.4.70_2.3.0).
We have some additional GPIO for output and input.
Could you please let us know how to set these direction in kernel?
We need to change device tree? Could you please show example?
Also, we need to get and set the value of GPIO in user space.

Any help would be appreciated.

Thank you.

Best regards,

[igorpadykov · Accepted solution]

Hi TANAKA

>Could you please let us know how to set these direction in kernel?
>We need to change device tree? Could you please show example?

not possible to set direction and set the value of GPIO in device tree, one can

set them in uboot, example:

https://source.codeaurora.org/external/imx/uboot-imx/tree/board/freescale/imx8mm_evk/spl.c?h=imx_v20...

https://source.codeaurora.org/external/imx/uboot-imx/tree/include/asm-generic/gpio.h?h=imx_v2020.04_...

>Also, we need to get and set the value of GPIO in user space.

one can look at example

https://variwiki.com/index.php?title=MX8M_GPIO&release=RELEASE_HARDKNOTT_V1.0_DART-MX8M-MINI

Best regards
igor

[tan-k]

Hi,

Thank you for your reply.
We referred to your URL and could set GPIO in uboot.
Also, we could set and get the value GPIO via /sys/class/gpio.

Best regards,