diff options
| author | Alexandre Belloni <alexandre.belloni@free-electrons.com> | 2016-08-30 05:57:06 +0300 |
|---|---|---|
| committer | Dmitry Torokhov <dmitry.torokhov@gmail.com> | 2016-08-30 06:00:58 +0300 |
| commit | 680772647d96ed853d20f837a2726151f24d8b20 (patch) | |
| tree | 79e7d495a74ca81775e13c6b5b1b4756baff67b6 /Documentation/devicetree/bindings/input | |
| parent | f959cd8c0eafe2bdaa9d0ec3e3da3b9451ad38aa (diff) | |
| download | linux-680772647d96ed853d20f837a2726151f24d8b20.tar.xz | |
Input: add ADC resistor ladder driver
A common way of multiplexing buttons on a single input in cheap devices is
to use a resistor ladder on an ADC. This driver supports that configuration
by polling an ADC channel provided by IIO.
Acked-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Diffstat (limited to 'Documentation/devicetree/bindings/input')
| -rw-r--r-- | Documentation/devicetree/bindings/input/adc-keys.txt | 49 |
1 files changed, 49 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/input/adc-keys.txt b/Documentation/devicetree/bindings/input/adc-keys.txt new file mode 100644 index 000000000000..e551814629b4 --- /dev/null +++ b/Documentation/devicetree/bindings/input/adc-keys.txt @@ -0,0 +1,49 @@ +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 at 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 ADC input when this key is pressed. + +Example: + +#include <dt-bindings/input/input.h> + + adc-keys { + compatible = "adc-keys"; + io-channels = <&lradc 0>; + io-channel-names = "buttons"; + keyup-threshold-microvolt = <2000000>; + + button-up { + label = "Volume Up"; + linux,code = <KEY_VOLUMEUP>; + press-threshold-microvolt = <1500000>; + }; + + button-down { + label = "Volume Down"; + linux,code = <KEY_VOLUMEDOWN>; + press-threshold-microvolt = <1000000>; + }; + + button-enter { + label = "Enter"; + linux,code = <KEY_ENTER>; + press-threshold-microvolt = <500000>; + }; + }; |