FocalTech EDT-FT5x06 Polytouch driver
=====================================

There are 5 variants of the chip for various touch panel sizes
FT5206GE1  2.8" .. 3.8"
FT5306DE4  4.3" .. 7"
FT5406EE8  7"   .. 8.9"
FT5506EEG  7"   .. 8.9"
FT5726NEI  5.7” .. 11.6"

The software interface is identical for all those chips, so that
currently there is no need for the driver to distinguish between the
different chips. Nevertheless distinct compatible strings are used so
that a distinction can be added if necessary without changing the DT
bindings.


Required properties:
 - compatible:  "edt,edt-ft5206"
           or:  "edt,edt-ft5306"
           or:  "edt,edt-ft5406"
           or:  "edt,edt-ft5506"
           or:  "evervision,ev-ft5726"
           or:  "focaltech,ft6236"

 - reg:         I2C slave address of the chip (0x38)
 - interrupts:       interrupt specification for the touchdetect
                     interrupt

Optional properties:
 - reset-gpios: GPIO specification for the RESET input
 - wake-gpios:  GPIO specification for the WAKE input
 - vcc-supply:  Regulator that supplies the touchscreen

 - pinctrl-names: should be "default"
 - pinctrl-0:   a phandle pointing to the pin settings for the
                control gpios

 - threshold:   allows setting the "click"-threshold in the range
                from 0 to 80.

 - gain:        allows setting the sensitivity in the range from 0 to
                31. Note that lower values indicate higher
                sensitivity.

 - offset:      allows setting the edge compensation in the range from
                0 to 31.

 - offset-x:    Same as offset, but applies only to the horizontal position.
                Range from 0 to 80, only supported by evervision,ev-ft5726
                devices.

 - offset-y:    Same as offset, but applies only to the vertical position.
                Range from 0 to 80, only supported by evervision,ev-ft5726
                devices.

 - touchscreen-size-x	   : See touchscreen.txt
 - touchscreen-size-y	   : See touchscreen.txt
 - touchscreen-fuzz-x      : See touchscreen.txt
 - touchscreen-fuzz-y      : See touchscreen.txt
 - touchscreen-inverted-x  : See touchscreen.txt
 - touchscreen-inverted-y  : See touchscreen.txt
 - touchscreen-swapped-x-y : See touchscreen.txt

Example:
	polytouch: edt-ft5x06@38 {
		compatible = "edt,edt-ft5406", "edt,edt-ft5x06";
		reg = <0x38>;
		pinctrl-names = "default";
		pinctrl-0 = <&edt_ft5x06_pins>;
		interrupt-parent = <&gpio2>;
		interrupts = <5 IRQ_TYPE_EDGE_FALLING>;
		reset-gpios = <&gpio2 6 GPIO_ACTIVE_LOW>;
		wake-gpios = <&gpio4 9 GPIO_ACTIVE_HIGH>;
	};