gpio-key-overlay.dts

// Definitions for gpio-key module
/dts-v1/;
/plugin/;

/ {
	compatible = "brcm,bcm2708";

	fragment@0 {
		// Configure the gpio pin controller
		target = <&gpio>;
		__overlay__ {
			pin_state: button_pins@0 {
				brcm,pins = <3>; // gpio number
				brcm,function = <0>; // 0 = input, 1 = output
				brcm,pull = <2>; // 0 = none, 1 = pull down, 2 = pull up
			};
		};
	};
	fragment@1 {
		target-path = "/";
		__overlay__ {
			button: button@0 {
				compatible = "gpio-keys";
				pinctrl-names = "default";
				pinctrl-0 = <&pin_state>;
				status = "okay";

				key: key {
					linux,code = <116>;
					gpios = <&gpio 3 1>;
					label = "KEY_POWER";
				};
			};
		};
	};

	__overrides__ {
		gpio =       <&key>,"gpios:4",
		             <&button>,"reg:0",
		             <&pin_state>,"brcm,pins:0",
		             <&pin_state>,"reg:0";
		label =      <&key>,"label";
		keycode =    <&key>,"linux,code:0";
		gpio_pull =  <&pin_state>,"brcm,pull:0";
		active_low = <&key>,"gpios:8";
	};

};