+ROCKCHIP ADC attached resistor ladder buttons
+------------------------------------
+
+Required properties:
+ - compatible: "rockchip,key"
+ - io-channels: Phandle to an ADC channel
+
+Each button (key) is represented as a sub-node of "rockchip,key":
+
+Required subnode-properties:
+ - label: Descriptive name of the key.
+ - linux,code: Keycode to emit.
+ - rockchip,adc_value:: Voltage ADC input when this key is pressed.
+
+Example:
+
+#include <dt-bindings/input/input.h>
+
+ rk_key: rockchip-key {
+ compatible = "rockchip,key";
+ status = "okay";
+
+ io-channels = <&saradc 1>;
+
+ vol-up-key {
+ linux,code = <115>;
+ label = "volume up";
+ rockchip,adc_value = <1>;
+ };
+
+ vol-down-key {
+ linux,code = <114>;
+ label = "volume down";
+ rockchip,adc_value = <170>;
+ };
+
+ power-key {
+ gpios = <&gpio0 5 GPIO_ACTIVE_LOW>;
+ linux,code = <116>;
+ pinctrl-names = "default";
+ pinctrl-0 = <&pwrbtn>;
+ label = "power";
+ gpio-key,wakeup;
+ };
+
+ menu-key {
+ linux,code = <59>;
+ label = "menu";
+ rockchip,adc_value = <355>;
+ };
+
+ home-key {
+ linux,code = <102>;
+ label = "home";
+ rockchip,adc_value = <746>;
+ };
+
+ back-key {
+ linux,code = <158>;
+ label = "back";
+ rockchip,adc_value = <560>;
+ };
+
+ camera-key {
+ linux,code = <212>;
+ label = "camera";
+ rockchip,adc_value = <450>;
+ };
+ };