ADC attached resistor ladder buttons ------------------------------------ Required properties: - compatible: "adc-keys" - io-channels: Phandle to an ADC channel - io-channel-names = "buttons"; - keyup-threshold-microvolt: Voltage above or equal to which all the keys are considered up. Optional properties: - poll-interval: Poll interval time in milliseconds - autorepeat: Boolean, Enable auto repeat feature of Linux input subsystem. Each button (key) is represented as a sub-node of "adc-keys": Required subnode-properties: - label: Descriptive name of the key. - linux,code: Keycode to emit. - press-threshold-microvolt: voltage above or equal to which this key is considered pressed. No two values of press-threshold-microvolt may be the same. All values of press-threshold-microvolt must be less than keyup-threshold-microvolt. Example: #include adc-keys { compatible = "adc-keys"; io-channels = <&lradc 0>; io-channel-names = "buttons"; keyup-threshold-microvolt = <2000000>; button-up { label = "Volume Up"; linux,code = ; press-threshold-microvolt = <1500000>; }; button-down { label = "Volume Down"; linux,code = ; press-threshold-microvolt = <1000000>; }; button-enter { label = "Enter"; linux,code = ; press-threshold-microvolt = <500000>; }; }; +--------------------------------+------------------------+ | 2.000.000 <= value | no key pressed | +--------------------------------+------------------------+ | 1.500.000 <= value < 2.000.000 | KEY_VOLUMEUP pressed | +--------------------------------+------------------------+ | 1.000.000 <= value < 1.500.000 | KEY_VOLUMEDOWN pressed | +--------------------------------+------------------------+ | 500.000 <= value < 1.000.000 | KEY_ENTER pressed | +--------------------------------+------------------------+ | value < 500.000 | no key pressed | +--------------------------------+------------------------+