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

// This overlay sets up an input device that generates KEY_POWER events
// when a given GPIO pin changes. It defaults to using GPIO3, which can
// also be used to wake up (start) the Rpi again after shutdown.
// Raspberry Pi 1 Model B rev 1 can be wake up only by GPIO1 pin, so for
// these boards change default GPIO pin to 1 via gpio_pin parameter. Since
// wakeup is active-low, this defaults to active-low with a pullup
// enabled, but all of this can be changed using overlay parameters (but
// note that GPIO3 has an external pullup on at least some boards).

/ {
	compatible = "brcm,bcm2835";

	fragment@0 {
		// Configure the gpio pin controller
		target = <&gpio>;
		__overlay__ {
			// Define a pinctrl state, that sets up the gpio
			// as an input with a pullup enabled. This does
			// not take effect by itself, only when referenced
			// by a "pinctrl client", as is done below. See:
			//   https://www.kernel.org/doc/Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt
			//   https://www.kernel.org/doc/Documentation/devicetree/bindings/pinctrl/brcm,bcm2835-gpio.txt
			pin_state: shutdown_button_pins@3 {
				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 {
		// Add a new device to the /soc devicetree node
		target-path = "/soc";
		__overlay__ {
			shutdown_button: shutdown_button@3 {
				// Let the gpio-keys driver handle this device. See:
				// https://www.kernel.org/doc/Documentation/devicetree/bindings/input/gpio-keys.txt
				compatible = "gpio-keys";

				// Declare a single pinctrl state (referencing the one declared above) and name it
				// default, so it is activated automatically.
				pinctrl-names = "default";
				pinctrl-0 = <&pin_state>;

				// Enable this device
				status = "okay";

				// Define a single key, called "shutdown" that monitors the gpio and sends KEY_POWER
				// (keycode 116, see
				// https://github.com/torvalds/linux/blob/v4.12/include/uapi/linux/input-event-codes.h#L190)
				button: shutdown {
					label = "shutdown";
					linux,code = <116>; // KEY_POWER
					gpios = <&gpio 3 1>;
					debounce-interval = <100>; // ms
				};
			};
		};
	};

	// This defines parameters that can be specified when loading
	// the overlay. Each foo = line specifies one parameter, named
	// foo. The rest of the specification gives properties where the
	// parameter value is inserted into (changing the values above
	// or adding new ones).
	__overrides__ {
		// Allow overriding the GPIO number.
		gpio_pin = <&button>,"gpios:4",
			   <&shutdown_button>,"reg:0",
			   <&pin_state>,"reg:0",
		           <&pin_state>,"brcm,pins:0";

		// Allow changing the internal pullup/down state. 0 = none, 1 = pulldown, 2 = pullup
		// Note that GPIO3 and GPIO2 are the I2c pins and have an external pullup (at least
		// on some boards). Same applies for GPIO1 on Raspberry Pi 1 Model B rev 1.
		gpio_pull = <&pin_state>,"brcm,pull:0";

		// Allow setting the active_low flag. 0 = active high, 1 = active low
		active_low = <&button>,"gpios:8";
		debounce = <&button>,"debounce-interval:0";
	};

};