Add DT binding document for PWM controlled vibrator devices.

Signed-off-by: Sebastian Reichel <sebastian.reic...@collabora.co.uk>
---
 .../devicetree/bindings/input/pwm-vibrator.txt     | 66 ++++++++++++++++++++++
 1 file changed, 66 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/input/pwm-vibrator.txt

diff --git a/Documentation/devicetree/bindings/input/pwm-vibrator.txt 
b/Documentation/devicetree/bindings/input/pwm-vibrator.txt
new file mode 100644
index 000000000000..09145d18491d
--- /dev/null
+++ b/Documentation/devicetree/bindings/input/pwm-vibrator.txt
@@ -0,0 +1,66 @@
+* PWM vibrator device tree bindings
+
+Registers a PWM device as vibrator. It is expected, that the vibrator's
+strength increases based on the duty cycle of the enable PWM channel
+(100% duty cycle meaning strongest vibration, 0% meaning no vibration).
+
+The binding supports an optional direction PWM channel, that can be
+driven at fixed duty cycle. If available this is can be used to increase
+the vibration effect of some devices.
+
+Required properties:
+- compatible: should contain "pwm-vibrator"
+- pwm-names: Should contain "enable" and optionally "direction"
+- pwms: Should contain a PWM handle for each entry in pwm-names
+
+Optional properties:
+- vcc-supply: Phandle for the regulator supplying power
+- direction-duty-cycle-ns: Duty cycle of the direction PWM channel in
+                           nanoseconds, defaults to 50% of the channel's
+                          period.
+
+Example from Motorola Droid 4:
+
+&omap4_pmx_core {
+       vibrator_direction_pin: pinmux_vibrator_direction_pin {
+               pinctrl-single,pins = <
+               OMAP4_IOPAD(0x1ce, PIN_OUTPUT | MUX_MODE1) /* dmtimer8_pwm_evt 
(gpio_27) */
+               >;
+       };
+
+       vibrator_enable_pin: pinmux_vibrator_enable_pin {
+               pinctrl-single,pins = <
+               OMAP4_IOPAD(0X1d0, PIN_OUTPUT | MUX_MODE1) /* dmtimer9_pwm_evt 
(gpio_28) */
+               >;
+       };
+};
+
+/ {
+       pwm8: dmtimer-pwm {
+               pinctrl-names = "default";
+               pinctrl-0 = <&vibrator_direction_pin>;
+
+               compatible = "ti,omap-dmtimer-pwm";
+               #pwm-cells = <3>;
+               ti,timers = <&timer8>;
+               ti,clock-source = <0x01>;
+       };
+
+       pwm9: dmtimer-pwm {
+               pinctrl-names = "default";
+               pinctrl-0 = <&vibrator_enable_pin>;
+
+               compatible = "ti,omap-dmtimer-pwm";
+               #pwm-cells = <3>;
+               ti,timers = <&timer9>;
+               ti,clock-source = <0x01>;
+       };
+
+       vibrator {
+               compatible = "pwm-vibrator";
+               pwms = <&pwm8 0 1000000000 0>,
+                      <&pwm9 0 1000000000 0>;
+               pwm-names = "enable", "direction";
+               direction-duty-cycle-ns = <1000000000>;
+       };
+};
-- 
2.13.2

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