Input: add support for the STMicroelectronics FingerTip touchscreen

The stmfts (ST-Microelectronics FingerTip S) touchscreen device is a
capacitive multi-touch controller mainly for mobile use.  It's connected
through i2c bus at the address 0x49 and it interfaces with userspace
through input event interface.

At the current state it provides a touchscreen multitouch functionality up
to 10 fingers. Each finger is enumerated with a distinctive id (from 0 to
9).

If enabled the device can support single "touch" hovering, by providing
three coordinates, x, y and distance.

It is possible to select the touchkey functionality which provides a basic
two keys interface for "home" and "back" menu, typical in mobile phones.

Signed-off-by: Andi Shyti <andi.shyti@samsung.com>
Reviewed-by: Javier Martinez Canillas <javier@osg.samsung.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Documentation/devicetree/bindings/input/touchscreen/st,stmfts.txt

@@ -0,0 +1,43 @@
+* ST-Microelectronics FingerTip touchscreen controller
+
+The ST-Microelectronics FingerTip device provides a basic touchscreen
+functionality. Along with it the user can enable the touchkey which can work as
+a basic HOME and BACK key for phones.
+
+The driver supports also hovering as an absolute single touch event with x, y, z
+coordinates.
+
+Required properties:
+- compatible		: must be "st,stmfts"
+- reg			: I2C slave address, (e.g. 0x49)
+- interrupt-parent	: the phandle to the interrupt controller which provides
+			  the interrupt
+- interrupts		: interrupt specification
+- avdd-supply		: analogic power supply
+- vdd-supply		: power supply
+- touchscreen-size-x	: see touchscreen.txt
+- touchscreen-size-y	: see touchscreen.txt
+
+Optional properties:
+- touch-key-connected	: specifies whether the touchkey feature is connected
+- ledvdd-supply		: power supply to the touch key leds
+
+Example:
+
+i2c@00000000 {
+
+	/* ... */
+
+	touchscreen@49 {
+		compatible = "st,stmfts";
+		reg = <0x49>;
+		interrupt-parent = <&gpa1>;
+		interrupts = <1 IRQ_TYPE_NONE>;
+		touchscreen-size-x = <1599>;
+		touchscreen-size-y = <2559>;
+		touch-key-connected;
+		avdd-supply = <&ldo30_reg>;
+		vdd-supply = <&ldo31_reg>;
+		ledvdd-supply = <&ldo33_reg>;
+	};
+};

drivers/input/touchscreen/Kconfig

@@ -1114,6 +1114,17 @@ config TOUCHSCREEN_ST1232
 	  To compile this driver as a module, choose M here: the
 	  module will be called st1232_ts.
 
+config TOUCHSCREEN_STMFTS
+	tristate "STMicroelectronics STMFTS touchscreen"
+	depends on I2C
+	depends on LEDS_CLASS
+	help
+	  Say Y here if you want support for STMicroelectronics
+	  STMFTS touchscreen.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called stmfts.
+
 config TOUCHSCREEN_STMPE
 	tristate "STMicroelectronics STMPE touchscreens"
 	depends on MFD_STMPE

drivers/input/touchscreen/Makefile

@@ -67,6 +67,7 @@ obj-$(CONFIG_TOUCHSCREEN_S3C2410)	+= s3c2410_ts.o
 obj-$(CONFIG_TOUCHSCREEN_SILEAD)	+= silead.o
 obj-$(CONFIG_TOUCHSCREEN_SIS_I2C)	+= sis_i2c.o
 obj-$(CONFIG_TOUCHSCREEN_ST1232)	+= st1232.o
+obj-$(CONFIG_TOUCHSCREEN_STMFTS)	+= stmfts.o
 obj-$(CONFIG_TOUCHSCREEN_STMPE)		+= stmpe-ts.o
 obj-$(CONFIG_TOUCHSCREEN_SUN4I)		+= sun4i-ts.o
 obj-$(CONFIG_TOUCHSCREEN_SUR40)		+= sur40.o