[PATCH v8 4/5] dt-bindings: input: pwm-beeper: add volume

[Manuel Traut <manuel.traut@mt.com>]

Adds an array of supported volume levels and a default volume level.

Signed-off-by: Manuel Traut <manuel.traut@mt.com>
---
 .../devicetree/bindings/input/pwm-beeper.yaml | 20 +++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/Documentation/devicetree/bindings/input/pwm-beeper.yaml b/Documentation/devicetree/bindings/input/pwm-beeper.yaml
index 351df83d5cbe..f1f9283ca855 100644
--- a/Documentation/devicetree/bindings/input/pwm-beeper.yaml
+++ b/Documentation/devicetree/bindings/input/pwm-beeper.yaml
@@ -26,6 +26,24 @@ properties:
   beeper-hz:
     description: bell frequency in Hz
 
+  volume-levels:
+    description: >
+      Array of PWM duty cycle values that correspond to
+      linear 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).
+    $ref: /schemas/types.yaml#/definitions/uint32-array
+
+  default-volume-level:
+    description: >
+      The default volume level (index into the array defined
+      by the "volume-levels" property).
+    $ref: /schemas/types.yaml#/definitions/uint32
+
 required:
   - compatible
   - pwms
@@ -45,4 +63,6 @@ examples:
       compatible = "pwm-beeper";
       pwms = <&pwm0>;
       amp-supply = <&beeper_amp>;
+      volume-levels = <0 8 20 40 500>;
+      default-volume-level = <4>;
     };
-- 
2.39.0