* 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" OR "st,fts" OR "st,fts2"
- reg			: I2C slave address, (e.g. 0x49). Or 0 for SPI interface
- interrupts		: interrupt specification
- avdd-supply		: analogic power supply
- vdd-supply		: power supply
- st,irq-gpio		: interrupt gpio.
- st,irq-flags		: irq trigger type config, , value should be:
				1 - rising edge,
				2 - falling edge,
				4 - high level,
				8 - low level.
- st,reset-gpio		: reset gpio
- st,regulator_dvdd	: dvdd regulator name
- st,regulator_avdd	: avdd regulator name

Example:

&i2c_6 {
	status = "ok";
	st_fts@49 {
		compatible = "st,fts";
		reg = <0x49>;

		interrupt-parent = <&tlmm>;
		interrupts = <162 0x2008>;
		vdd-supply = <&L4B>;
		avdd-supply = <&L14B>;
		st,irq-gpio = <&tlmm 162 0x2008>;
		st,irq-flags = <8>;
		st,reset-gpio = <&tlmm 161 0x00>;
		st,regulator_dvdd = "vdd";
		st,regulator_avdd = "avdd";
	};
};
