Reconfigure Power Button to GPIO input

[djrichter]

Hello,
Is it possible to reconfigure the PowerButton (sleep/wake Pin 240 / Jetson Nano) to be a general purpose IO? If so, how best to accomplish this?

Thank you

[JerryChang]

hello djrichter,

this pin is by default configured as GPIO already.
as you can see, it’s defined in the device tree as following,

        gpio-keys {
                power {
                        label = "Power";
                        gpios = <&gpio TEGRA_GPIO(X, 5) GPIO_ACTIVE_LOW>;
                        linux,code = <KEY_POWER>;

[djrichter]

Sorry for being not more specific. How can I access the gpio value similar to the other gpio’s?
export 189 > /sys/class/gpio/export
“write error: Device or resource buys”
cat /sys/class/gpio/gpio189/value

[JerryChang]

hello djrichter,

this GPIO pin is already occupied as power key.
you may need to revise the device tree to reconfigure this pin.

[djrichter]

Looking at the Nvidia PinMux spreadsheet, the Sleep/Wake/pin 240/Button Power pin has 2 possible options: “GPIO3_PX.05” or “unused”. Other pins have multiple options. With GPIO3_PX.05 selected, the pin behavior is power button.

From the stand point, “I don’t know what I don’t know”, can you be more specific?

[JerryChang]

hello djrichter,

do you have an alternative way to power-on the target?
if yes, you’ll need to remove those gpio-keys device tree definitions, then you should able to toggle PX.05 as GPIO.