Input: touchscreen - add imx6ul_tsc driver support

Freescale i.MX6UL contains a internal touchscreen controller,
this patch add a driver to support this controller.
Signed-off-by: Haibo Chen <haibo.chen@freescale.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Documentation/devicetree/bindings/input/touchscreen/imx6ul_tsc.txt

+* Freescale i.MX6UL Touch Controller
+
+Required properties:
+- compatible: must be "fsl,imx6ul-tsc".
+- reg: this touch controller address and the ADC2 address.
+- interrupts: the interrupt of this touch controller and ADC2.
+- clocks: the root clock of touch controller and ADC2.
+- clock-names; must be "tsc" and "adc".
+- xnur-gpio: the X- gpio this controller connect to.
+  This xnur-gpio returns to low once the finger leave the touch screen (The
+  last touch event the touch controller capture).
+
+Optional properties:
+- measure-delay-time: the value of measure delay time.
+  Before X-axis or Y-axis measurement, the screen need some time before
+  even potential distribution ready.
+  This value depends on the touch screen.
+- pre-charge-time: the touch screen need some time to precharge.
+  This value depends on the touch screen.
+
+Example:
+	tsc: tsc@02040000 {
+		compatible = "fsl,imx6ul-tsc";
+		reg = <0x02040000 0x4000>, <0x0219c000 0x4000>;
+		interrupts = <GIC_SPI 3 IRQ_TYPE_LEVEL_HIGH>,
+			     <GIC_SPI 101 IRQ_TYPE_LEVEL_HIGH>;
+		clocks = <&clks IMX6UL_CLK_IPG>,
+			 <&clks IMX6UL_CLK_ADC2>;
+		clock-names = "tsc", "adc";
+		pinctrl-names = "default";
+		pinctrl-0 = <&pinctrl_tsc>;
+		xnur-gpio = <&gpio1 3 GPIO_ACTIVE_LOW>;
+		measure-delay-time = <0xfff>;
+		pre-charge-time = <0xffff>;
+		status = "okay";
+	};

drivers/input/touchscreen/Kconfig

@@ -479,6 +479,18 @@ config TOUCHSCREEN_MTOUCH
 	  To compile this driver as a module, choose M here: the
 	  module will be called mtouch.
 
+config TOUCHSCREEN_IMX6UL_TSC
+	tristate "Freescale i.MX6UL touchscreen controller"
+	depends on (OF && GPIOLIB) || COMPILE_TEST
+	help
+	  Say Y here if you have a Freescale i.MX6UL, and want to
+	  use the internal touchscreen controller.
+
+	  If unsure, say N.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called imx6ul_tsc.
+
 config TOUCHSCREEN_INEXIO
 	tristate "iNexio serial touchscreens"
 	select SERIO

drivers/input/touchscreen/Makefile

@@ -38,6 +38,7 @@ obj-$(CONFIG_TOUCHSCREEN_EGALAX)	+= egalax_ts.o
 obj-$(CONFIG_TOUCHSCREEN_FUJITSU)	+= fujitsu_ts.o
 obj-$(CONFIG_TOUCHSCREEN_GOODIX)	+= goodix.o
 obj-$(CONFIG_TOUCHSCREEN_ILI210X)	+= ili210x.o
+obj-$(CONFIG_TOUCHSCREEN_IMX6UL_TSC)	+= imx6ul_tsc.o
 obj-$(CONFIG_TOUCHSCREEN_INEXIO)	+= inexio.o
 obj-$(CONFIG_TOUCHSCREEN_INTEL_MID)	+= intel-mid-touch.o
 obj-$(CONFIG_TOUCHSCREEN_IPROC)		+= bcm_iproc_tsc.o