Documentation/devicetree/bindings/input/adc-keys.txt

   1 ADC attached resistor ladder buttons
   2 ------------------------------------
   3
   4 Required properties:
   5  - compatible: "adc-keys"
   6  - io-channels: Phandle to an ADC channel
   7  - io-channel-names = "buttons";
   8  - keyup-threshold-microvolt: Voltage at which all the keys are considered up.
   9
  10 Optional properties:
  11         - poll-interval: Poll interval time in milliseconds
  12         - autorepeat: Boolean, Enable auto repeat feature of Linux input
  13           subsystem.
  14
  15 Each button (key) is represented as a sub-node of "adc-keys":
  16
  17 Required subnode-properties:
  18         - label: Descriptive name of the key.
  19         - linux,code: Keycode to emit.
  20         - press-threshold-microvolt: Voltage ADC input when this key is pressed.
  21
  22 Example:
  23
  24 #include <dt-bindings/input/input.h>
  25
  26         adc-keys {
  27                 compatible = "adc-keys";
  28                 io-channels = <&lradc 0>;
  29                 io-channel-names = "buttons";
  30                 keyup-threshold-microvolt = <2000000>;
  31
  32                 button-up {
  33                         label = "Volume Up";
  34                         linux,code = <KEY_VOLUMEUP>;
  35                         press-threshold-microvolt = <1500000>;
  36                 };
  37
  38                 button-down {
  39                         label = "Volume Down";
  40                         linux,code = <KEY_VOLUMEDOWN>;
  41                         press-threshold-microvolt = <1000000>;
  42                 };
  43
  44                 button-enter {
  45                         label = "Enter";
  46                         linux,code = <KEY_ENTER>;
  47                         press-threshold-microvolt = <500000>;
  48                 };
  49         };