arm64: dts: rockchip: add power button support for Firefly-RK3399

This commit adds power button support for the Firefly-RK3399.
Signed-off-by: NShohei Maruyama <cheat.sc.linux@outlook.com>
Signed-off-by: NHeiko Stuebner <heiko@sntech.de>

arch/arm64/boot/dts/rockchip/rk3399-firefly.dts

@@ -4,6 +4,7 @@
  */
 
 /dts-v1/;
+#include <dt-bindings/input/linux-event-codes.h>
 #include <dt-bindings/pwm/pwm.h>
 #include "rk3399.dtsi"
 #include "rk3399-opp.dtsi"
@@ -72,6 +73,21 @@
 		regulator-max-microvolt = <12000000>;
 	};
 
+	gpio-keys {
+		compatible = "gpio-keys";
+		autorepeat;
+		pinctrl-names = "default";
+		pinctrl-0 = <&pwrbtn>;
+
+		power {
+			debounce-interval = <100>;
+			gpios = <&gpio0 RK_PA5 GPIO_ACTIVE_LOW>;
+			label = "GPIO Key Power";
+			linux,code = <KEY_POWER>;
+			wakeup-source;
+		};
+	};
+
 	rt5640-sound {
 		compatible = "simple-audio-card";
 		simple-audio-card,name = "rockchip,rt5640-codec";