How to access GPIO through SYSFS? How to re-assign the direction and use of GPIO from the user space?

ARM Boards & Solutions i.MX 8
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  • Using Linux 6.6.23, with Hardware G40M i.MX8MP OSM SBC “imx8mp-iwg40m-osm.dtsi” - this dts is specifically for i.MX8MP OSM SBC. Note: It is not a generic dts.
  • Please refer Software User Guide, section Device tree source desciption for detailed explanation on each dts and dtb files.
  • All the GPIOs mentioned is dts are configured for specific interfaces according to our Hardware design. Once any GPIO is configured in dts for any interfaces, it cannot be accessed in user space by the user.
  • All the GPIOs which can be accessed by the user in userspace is mentioned in node “pinctrl_expansion_gpio” in dts “arch/arm64/boot/dts/freescale/imx8mp-iwg40s-prgjj.dts”
  • If any GPIO wants to be accessed from userspace, follow below points:
    1. Configure the required GPIOs in node “pinctrl_expansion_gpio” in dts “arch/arm64/boot/dts/freescale/imx8mp-iwg40s-prgjj.dts”
    2. Any PAD/GPIOs cannot be configured twice - ex: same GPIO PAD cannot be configured for any interfaces and in “pinctrl_expansion_gpio”- this will create the conflict and GPIO will not work as expected.
    3. Make sure to remove any duplicate GPIO configuration in dts
  • Once the GPIO is configured in dts node “pinctrl_expansion_gpio”, same GPIO can be accessed in userspace using sysfs command. Refer Software User Guide, section GPIO sysfs Test for detailed explanation.

For further inquiries, please get in touch with mktg@iwave-global.com

Please find the detailed G40M product information in the below link,