Input: synaptics-rmi4 - add device tree support for RMI4 I2C devices

Add devicetree binding for I2C devices and add bindings for optional
parameters in the function drivers. Parameters for function drivers are
defined in child nodes for each of the functions.

Signed-off-by: Andrew Duggan <aduggan@synaptics.com>
Acked-by: Rob Herring <robh@kernel.org>
Tested-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Tested-by: Linus Walleij <linus.walleij@linaro.org>
Tested-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Documentation/devicetree/bindings/input/rmi4/rmi_f01.txt

@@ -0,0 +1,39 @@
+Synaptics RMI4 F01 Device Binding
+
+The Synaptics RMI4 core is able to support RMI4 devices using different
+transports and different functions. This file describes the device tree
+bindings for devices which contain Function 1. Complete documentation
+for transports and other functions can be found in:
+Documentation/devicetree/bindings/input/rmi4.
+
+Additional documentation for F01 can be found at:
+http://www.synaptics.com/sites/default/files/511-000136-01-Rev-E-RMI4-Interfacing-Guide.pdf
+
+Optional Properties:
+- syna,nosleep-mode: If set the device will run at full power without sleeping.
+			nosleep has 3 modes, 0 will not change the default
+			setting, 1 will disable nosleep (allow sleeping),
+			and 2 will enable nosleep (disabling sleep).
+- syna,wakeup-threshold: Defines the amplitude of the disturbance to the
+				background capacitance that will cause the
+				device to wake from dozing.
+- syna,doze-holdoff-ms: The delay to wait after the last finger lift and the
+				first doze cycle.
+- syna,doze-interval-ms: The time period that the device sleeps between finger
+				activity.
+
+
+Example of a RMI4 I2C device with F01:
+	Example:
+	&i2c1 {
+		rmi4-i2c-dev@2c {
+			compatible = "syna,rmi4-i2c";
+
+			...
+
+			rmi4-f01@1 {
+				reg = <0x1>;
+				syna,nosleep-mode = <1>;
+			};
+		};
+	};

Documentation/devicetree/bindings/input/rmi4/rmi_i2c.txt

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+Synaptics RMI4 I2C Device Binding
+
+The Synaptics RMI4 core is able to support RMI4 devices using different
+transports and different functions. This file describes the device tree
+bindings for devices using the I2C transport driver. Complete documentation
+for other transports and functions can be found in
+Documentation/devicetree/bindings/input/rmi4.
+
+Required Properties:
+- compatible: syna,rmi4-i2c
+- reg: I2C address
+- #address-cells: Set to 1 to indicate that the function child nodes
+		    consist of only on uint32 value.
+- #size-cells: Set to 0 to indicate that the function child nodes do not
+		have a size property.
+
+Optional Properties:
+- interrupts: interrupt which the rmi device is connected to.
+- interrupt-parent: The interrupt controller.
+See Documentation/devicetree/bindings/interrupt-controller/interrupts.txt
+
+- syna,reset-delay-ms: The number of milliseconds to wait after resetting the
+			device.
+
+Function Parameters:
+Parameters specific to RMI functions are contained in child nodes of the rmi device
+ node. Documentation for the parameters of each function can be found in:
+Documentation/devicetree/bindings/input/rmi4/rmi_f*.txt.
+
+
+
+Example:
+	&i2c1 {
+		rmi4-i2c-dev@2c {
+			compatible = "syna,rmi4-i2c";
+			reg = <0x2c>;
+			#address-cells = <1>;
+			#size-cells = <0>;
+			interrupt-parent = <&gpio>;
+			interrupts = <4 2>;
+
+			rmi4-f01@1 {
+				reg = <0x1>;
+				syna,nosleep-mode = <1>;
+			};
+
+			rmi4-f11@11 {
+				reg = <0x11>;
+				touchscreen-inverted-y;
+				syna,sensor-type = <2>;
+			};
+		};
+	};