Devicetree overlay for simple GPIO

[Lorozco]

It seems like there are lots of questions regarding simple GPIOs and devicetree, but I can't quite find something that describes my problem:

I am using the nrf52840dk, and I successfully created an overlay file to read/write to an I2C device, but I am having trouble adding a simple GPIO pin to my overlay file.

First, I tried adding the following to my overlay file:

columnswitchint: column_switch_input

    {

             compatible = "gpio-keys";

            gpios = <&gpio0 2 GPIO_ACTIVE_LOW>;

            label = "Column Switch Input Signal";

    };

When I try to build, I get the error "Property not mentioned in "/" ".  

Next, I tried declaring the pin like the 'buttons' definition in the .dts file for the blinky example:

sample_gpio_signals

{

    compatible = "gpio-keys";

    columnswitchint: column_switch_input

    {

           

            gpios = <&gpio0 2 GPIO_ACTIVE_LOW>;

            label = "Column Switch Interrupt Signal";

    };

};

This results in the error "Node column_switch_input should have "compatible" property".

Finally, I tried moving the compatible property down into the node:

sample_gpio_signals

{

    columnswitchint: column_switch_input

    {

   

            compatible = "gpio-keys";

            gpios = <&gpio0 2 GPIO_ACTIVE_LOW>;

            label = "Column Switch Interrupt Signal";

    };

};

And this results in the error "Property not mentioned in "gpio-keys".  Obviously 'gpios' is one of the only two properties declared in gpio-keys, so I'm stuck.

What am I missing here?  

[Lorozco]

..and I apologize in advance for the terrible formatting!