* 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>;
	};
};