arm64: tegra: Add gpio-keys nodes for Smaug

Add gpio-keys nodes for the volumn controls, lid switch, tablet mode and
power button.
Signed-off-by: NRhyland Klein <rklein@nvidia.com>
Reviewed-by: NAndrew Bresticker <abrestic@chromium.org>
[treding@nvidia.com: use symbolic names for input types and codes]
[treding@nvidia.com: use wakeup-source instead of gpio-key,wakeup]
Signed-off-by: NThierry Reding <treding@nvidia.com>

arch/arm64/boot/dts/nvidia/tegra210-smaug.dts

 /dts-v1/;
 
+#include <dt-bindings/input/input.h>
+
 #include "tegra210.dtsi"
 
 / {
@@ -76,6 +78,47 @@
 		};
 	};
 
+	gpio-keys {
+		compatible = "gpio-keys";
+		gpio-keys,name = "gpio-keys";
+
+		power {
+			label = "Power";
+			gpios = <&gpio TEGRA_GPIO(X, 5) GPIO_ACTIVE_LOW>;
+			linux,code = <KEY_POWER>;
+			debounce-interval = <30>;
+			wakeup-source;
+		};
+
+		lid {
+			label = "Lid";
+			gpios = <&gpio TEGRA_GPIO(B, 4) GPIO_ACTIVE_LOW>;
+			linux,input-type = <EV_SW>;
+			linux,code = <SW_LID>;
+			wakeup-source;
+		};
+
+		tablet_mode {
+			label = "Tablet Mode";
+			gpios = <&gpio TEGRA_GPIO(Z, 2) GPIO_ACTIVE_HIGH>;
+			linux,input-type = <EV_SW>;
+			linux,code = <SW_TABLET_MODE>;
+			wakeup-source;
+		};
+
+		volume_down {
+			label = "Volume Down";
+			gpios = <&gpio TEGRA_GPIO(X, 7) GPIO_ACTIVE_LOW>;
+			linux,code = <KEY_VOLUMEDOWN>;
+		};
+
+		volume_up {
+			label = "Volume Up";
+			gpios = <&gpio TEGRA_GPIO(M, 4) GPIO_ACTIVE_LOW>;
+			linux,code = <KEY_VOLUMEUP>;
+		};
+	};
+
 	psci {
 		compatible = "arm,psci-1.0";
 		method = "smc";