Input: add support for the Samsung S6SY761 touchscreen

The S6SY761 touchscreen is a capicitive multi-touch controller
for mobile use. It's connected with i2c at the address 0x48.

This commit provides a basic version of the driver which can
handle only initialization, touch events and power states.

The controller is controlled by a firmware which, in the version
I currently have, doesn't provide all the possible
functionalities mentioned in the datasheet.
Signed-off-by: Andi Shyti <andi.shyti@samsung.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Documentation/devicetree/bindings/input/touchscreen/samsung,s6sy761.txt

+* Samsung S6SY761 touchscreen controller
+
+Required properties:
+- compatible		: must be "samsung,s6sy761"
+- reg			: I2C slave address, (e.g. 0x48)
+- interrupt-parent	: the phandle to the interrupt controller which provides
+			  the interrupt
+- interrupts		: interrupt specification
+- avdd-supply		: analogic power supply
+- vdd-supply		: power supply
+
+Optional properties:
+- touchscreen-size-x	: see touchscreen.txt. This property is embedded in the
+			  device. If defined it forces a different x resolution.
+- touchscreen-size-y	: see touchscreen.txt. This property is embedded in the
+			  device. If defined it forces a different y resolution.
+
+Example:
+
+i2c@00000000 {
+
+	/* ... */
+
+	touchscreen@48 {
+		compatible = "samsung,s6sy761";
+		reg = <0x48>;
+		interrupt-parent = <&gpa1>;
+		interrupts = <1 IRQ_TYPE_NONE>;
+		avdd-supply = <&ldo30_reg>;
+		vdd-supply = <&ldo31_reg>;
+		touchscreen-size-x = <4096>;
+		touchscreen-size-y = <4096>;
+	};
+};

drivers/input/touchscreen/Kconfig

@@ -404,6 +404,17 @@ config TOUCHSCREEN_S3C2410
 	  To compile this driver as a module, choose M here: the
 	  module will be called s3c2410_ts.
 
+config TOUCHSCREEN_S6SY761
+	tristate "Samsung S6SY761 Touchscreen driver"
+	depends on I2C
+	help
+	  Say Y if you have the Samsung S6SY761 driver
+
+	  If unsure, say N
+
+	  To compile this driver as module, choose M here: the
+	  module will be called s6sy761.
+
 config TOUCHSCREEN_GUNZE
 	tristate "Gunze AHL-51S touchscreen"
 	select SERIO

drivers/input/touchscreen/Makefile

@@ -67,6 +67,7 @@ obj-$(CONFIG_TOUCHSCREEN_PENMOUNT)	+= penmount.o
 obj-$(CONFIG_TOUCHSCREEN_PIXCIR)	+= pixcir_i2c_ts.o
 obj-$(CONFIG_TOUCHSCREEN_RM_TS)		+= raydium_i2c_ts.o
 obj-$(CONFIG_TOUCHSCREEN_S3C2410)	+= s3c2410_ts.o
+obj-$(CONFIG_TOUCHSCREEN_S6SY761)	+= s6sy761.o
 obj-$(CONFIG_TOUCHSCREEN_SILEAD)	+= silead.o
 obj-$(CONFIG_TOUCHSCREEN_SIS_I2C)	+= sis_i2c.o
 obj-$(CONFIG_TOUCHSCREEN_ST1232)	+= st1232.o