Add documentation for ADC keys
Signed-off-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxxxxxxxxx>
---
Cc: Rob Herring <robh+dt@xxxxxxxxxx>
Cc: devicetree@xxxxxxxxxxxxxxx
.../devicetree/bindings/input/adc-keys.txt | 49 ++++++++++++++++++++++
1 file changed, 49 insertions(+)
create mode 100644 Documentation/devicetree/bindings/input/adc-keys.txt
diff --git a/Documentation/devicetree/bindings/input/adc-keys.txt b/Documentation/devicetree/bindings/input/adc-keys.txt
new file mode 100644
index 000000000000..0b92ebb4ac21
--- /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-mvolt: Voltage at which all the keys are considered up.
+
+Optional properties:
+ - 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-mvolt: 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-mvolt = <2000>;
+
+ button@1500 {
+ label = "Volume Up";
+ linux,code = <KEY_VOLUMEUP>;
+ press-threshold-mvolt = <1500>;
+ };
+
+ button@1000 {
+ label = "Volume Down";
+ linux,code = <KEY_VOLUMEDOWN>;
+ press-threshold-mvolt = <1000>;
+ };
+
+ button@500 {
+ label = "Enter";
+ linux,code = <KEY_ENTER>;
+ press-threshold-mvolt = <500>;
+ };
+ };
+
--
2.8.1
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