mirror of
https://github.com/AsahiLinux/u-boot
synced 2024-12-21 02:33:07 +00:00
68 lines
2 KiB
Text
68 lines
2 KiB
Text
|
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 <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>;
|
||
|
|
};
|
||
|
|
};
|
||
|
|
|
||
|
|
+--------------------------------+------------------------+
|
||
|
|
| 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 |
|
||
|
|
+--------------------------------+------------------------+
|