This patch adds the documentation for the devicetree bindings to set
the volume levels.
Signed-off-by: Frieder Schrempf <frieder.schrempf@xxxxxxxxx>
---
Changes in v2:
- split into 3 separate patches
- make volume properties optional
.../devicetree/bindings/input/pwm-beeper.txt | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
diff --git a/Documentation/devicetree/bindings/input/pwm-beeper.txt b/Documentation/devicetree/bindings/input/pwm-beeper.txt
index be332ae..6d8ba4e 100644
--- a/Documentation/devicetree/bindings/input/pwm-beeper.txt
+++ b/Documentation/devicetree/bindings/input/pwm-beeper.txt
@@ -5,3 +5,25 @@ Registers a PWM device as beeper.
Required properties:
- compatible: should be "pwm-beeper"
- pwms: phandle to the physical PWM device
+
+Optional properties:
+- volume-levels: Array of distinct volume levels. These need to be in the
+ range of 0 to 500, while 0 means 0% duty cycle (mute) and 500 means
+ 50% duty cycle (max volume).
+ Please note that the actual volume of most beepers is highly
+ non-linear, which means that low volume levels are probably somewhere
+ in the range of 1 to 30 (0.1-3% duty cycle).
+- default-volume-level: the default volume level (index into the
+ array defined by the "volume-levels" property)
+
+The volume level can be set via sysfs under /sys/class/input/inputX/volume.
+The maximum volume level index can be read from /sys/class/input/inputX/max_volume_level.
+
+Example:
+
+ pwm-beeper {
+ compatible = "pwm-beeper";
+ pwms = <&pwm4 0 5000>;
+ volume-levels = <0 8 20 40 500>;
+ default-volume-level = <4>;
+ };
--
1.9.1
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