Specifying wakeup capability for devices
============================================

Any device nodes
----------------
Nodes that describe devices which have wakeup capability may contain a
"wakeup-source" boolean property.

If the device is marked as a wakeup-source, interrupt wake capability depends
on the device specific "interrupt-names" property. If no interrupts are labeled
as wake capable, then it is up to the device to determine which interrupts can
wake the system.

However if a device has a dedicated interrupt as the wakeup source, then it
needs to specify/identify it using a device specific interrupt name. In such
cases only that interrupt can be used as a wakeup interrupt.

While various legacy interrupt names exist, new devices should use "wakeup" as
the canonical interrupt name.

List of legacy properties and respective binding document
---------------------------------------------------------

1. "gpio-key,wakeup"		Documentation/devicetree/bindings/input/gpio-keys{,-polled}.txt
2. "has-tpo"			Documentation/devicetree/bindings/rtc/rtc-opal.txt
3. "linux,wakeup"		Documentation/devicetree/bindings/input/gpio-matrix-keypad.yaml
				Documentation/devicetree/bindings/mfd/tc3589x.txt
				Documentation/devicetree/bindings/input/touchscreen/ti,ads7843.yaml
4. "linux,keypad-wakeup"	Documentation/devicetree/bindings/input/qcom,pm8921-keypad.yaml
5. "linux,input-wakeup"		Documentation/devicetree/bindings/input/samsung,s3c6410-keypad.yaml
6. "nvidia,wakeup-source"	Documentation/devicetree/bindings/input/nvidia,tegra20-kbc.txt

Examples
--------

1. With "wakeup" interrupt name

	device@10000 {
		compatible	= "vendor,device-id";
		reg		= <0x10000 0x1000>;
		interrupts	= <0 19 4>, <0 21 4>, <0 22 4>;
		interrupt-names	= "ack", "err", "wakeup";
		wakeup-source;
	};

2. Without "wakeup" interrupt name

	embedded-controller {
		compatible = "google,cros-ec-i2c";
		reg = <0x1e>;
		interrupts = <6 0>;
		interrupt-parent = <&gpx1>;
		pinctrl-names = "default";
		pinctrl-0 = <&ec_irq>;
		wakeup-source;
	};

3. Without interrupts

	gpio_keys {
		compatible = "gpio-keys";
		#address-cells = <1>;
		#size-cells = <0>;

		button@1 {
			debounce-interval = <50>;
			wakeup-source;
			linux,code = <116>;
			label = "POWER";
			gpios = <&iofpga_gpio0 0 0x4>;
		};
		[....]
	};
