Input: add driver for Silead touchscreens

This driver adds support for Silead touchscreens. It has been tested
with GSL1680 and GSL3680 touch panels.

It supports ACPI and device tree enumeration. Screen resolution,
the maximum number of fingers supported and firmware name are
configurable.
Signed-off-by: Robert Dolca <robert.dolca@intel.com>
Signed-off-by: Daniel Jansen <djaniboe@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Documentation/devicetree/bindings/input/touchscreen/silead_gsl1680.txt

+* GSL 1680 touchscreen controller
+
+Required properties:
+- compatible		  : "silead,gsl1680"
+- reg			  : I2C slave address of the chip (0x40)
+- interrupt-parent	  : a phandle pointing to the interrupt controller
+			    serving the interrupt for this chip
+- interrupts		  : interrupt specification for the gsl1680 interrupt
+- power-gpios		  : Specification for the pin connected to the gsl1680's
+			    shutdown input. This needs to be driven high to take the
+			    gsl1680 out of its low power state
+- touchscreen-size-x	  : See touchscreen.txt
+- touchscreen-size-y	  : See touchscreen.txt
+
+Optional properties:
+- touchscreen-inverted-x  : See touchscreen.txt
+- touchscreen-inverted-y  : See touchscreen.txt
+- touchscreen-swapped-x-y : See touchscreen.txt
+- silead,max-fingers	  : maximum number of fingers the touchscreen can detect
+
+Example:
+
+i2c@00000000 {
+	gsl1680: touchscreen@40 {
+		compatible = "silead,gsl1680";
+		reg = <0x40>;
+		interrupt-parent = <&pio>;
+		interrupts = <6 11 IRQ_TYPE_EDGE_FALLING>;
+		power-gpios = <&pio 1 3 GPIO_ACTIVE_HIGH>;
+		touchscreen-size-x = <480>;
+		touchscreen-size-y = <800>;
+		touchscreen-inverted-x;
+		touchscreen-swapped-x-y;
+		silead,max-fingers = <5>;
+	};
+};

drivers/input/touchscreen/Kconfig

@@ -1059,6 +1059,18 @@ config TOUCHSCREEN_RM_TS
 	  To compile this driver as a module, choose M here: the
 	  module will be called raydium_i2c_ts.
 
+config TOUCHSCREEN_SILEAD
+	tristate "Silead I2C touchscreen"
+	depends on I2C
+	help
+	  Say Y here if you have the Silead touchscreen connected to
+	  your system.
+
+	  If unsure, say N.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called silead.
+
 config TOUCHSCREEN_ST1232
 	tristate "Sitronix ST1232 touchscreen controllers"
 	depends on I2C

drivers/input/touchscreen/Makefile

@@ -64,6 +64,7 @@ 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-$(CONFIG_TOUCHSCREEN_SILEAD)	+= silead.o
 obj-$(CONFIG_TOUCHSCREEN_ST1232)	+= st1232.o
 obj-$(CONFIG_TOUCHSCREEN_STMPE)		+= stmpe-ts.o
 obj-$(CONFIG_TOUCHSCREEN_SUN4I)		+= sun4i-ts.o