Input: add a driver for GPIO controllable vibrators

Provide a simple driver for GPIO controllable vibrators.
It will be used by the Fairphone 2.

Signed-off-by: Luca Weiss <luca@z3ntu.xyz>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Documentation/devicetree/bindings/input/gpio-vibrator.yaml

@@ -0,0 +1,37 @@
+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/bindings/input/gpio-vibrator.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: GPIO vibrator
+
+maintainers:
+  - Luca Weiss <luca@z3ntu.xyz>
+
+description: |+
+  Registers a GPIO device as vibrator, where the on/off capability is controlled by a GPIO.
+
+properties:
+  compatible:
+    const: gpio-vibrator
+
+  enable-gpios:
+    maxItems: 1
+
+  vcc-supply:
+    description: Regulator that provides power
+
+required:
+  - compatible
+  - enable-gpios
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    vibrator {
+        compatible = "gpio-vibrator";
+        enable-gpios = <&msmgpio 86 GPIO_ACTIVE_HIGH>;
+        vcc-supply = <&pm8941_l18>;
+    };