Input: add Atmel Captouch Button driver

Add I2C driver for Atmel Capacitive Touch Button device.

Signed-off-by: Hung-yu Wu <hywu@google.com>
Signed-off-by: Grant Grundler <grundler@chromium.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Documentation/devicetree/bindings/input/atmel,captouch.txt

@@ -0,0 +1,36 @@
+Device tree bindings for Atmel capacitive touch device, typically
+an Atmel touch sensor connected to AtmegaXX MCU running firmware
+based on Qtouch library.
+
+The node for this device must be a child of a I2C controller node, as the
+device communicates via I2C.
+
+Required properties:
+
+	compatible:	Must be "atmel,captouch".
+	reg:		The I2C slave address of the device.
+	interrupts:	Property describing the interrupt line the device
+			is connected to. The device only has one interrupt
+			source.
+	linux,keycodes:	Specifies an array of numeric keycode values to
+			be used for reporting button presses. The array can
+			contain up to 8 entries.
+
+Optional properties:
+
+	autorepeat:	Enables the Linux input system's autorepeat
+			feature on the input device.
+
+Example:
+
+	atmel-captouch@51 {
+		compatible = "atmel,captouch";
+		reg = <0x51>;
+		interrupt-parent = <&tlmm>;
+		interrupts = <67 IRQ_TYPE_EDGE_FALLING>;
+		linux,keycodes = <BTN_0>, <BTN_1>,
+			<BTN_2>, <BTN_3>,
+			<BTN_4>, <BTN_5>,
+			<BTN_6>, <BTN_7>;
+		autorepeat;
+	};