* Cypress cyttsp touchscreen controller

Required properties:
 - compatible		: must be "cypress,cyttsp-i2c" or "cypress,cyttsp-spi"
 - reg			: Device I2C address or SPI chip select number
 - spi-max-frequency	: Maximum SPI clocking speed of the device (for cyttsp-spi)
 - interrupts		: (gpio) interrupt to which the chip is connected
			  (see interrupt binding[0]).
 - bootloader-key	: the 8-byte bootloader key that is required to switch
			  the chip from bootloader mode (default mode) to
			  application mode.
			  This property has to be specified as an array of 8
			  '/bits/ 8' values.

Optional properties:
 - reset-gpios		: the reset gpio the chip is connected to
			  (see GPIO binding[1] for more details).
 - touchscreen-size-x	: horizontal resolution of touchscreen (in pixels)
 - touchscreen-size-y	: vertical resolution of touchscreen (in pixels)
 - touchscreen-fuzz-x	: horizontal noise value of the absolute input device
			  (in pixels)
 - touchscreen-fuzz-y	: vertical noise value of the absolute input device
			  (in pixels)
 - active-distance	: the distance in pixels beyond which a touch must move
			  before movement is detected and reported by the device.
			  Valid values: 0-15.
 - active-interval-ms	: the minimum period in ms between consecutive
			  scanning/processing cycles when the chip is in active mode.
			  Valid values: 0-255.
 - lowpower-interval-ms	: the minimum period in ms between consecutive
			  scanning/processing cycles when the chip is in low-power mode.
			  Valid values: 0-2550
 - touch-timeout-ms	: minimum time in ms spent in the active power state while no
			  touches are detected before entering low-power mode.
			  Valid values: 0-2550
 - use-handshake	: enable register-based handshake (boolean). This should
			  only be used if the chip is configured to use 'blocking
			  communication with timeout' (in this case the device
			  generates an interrupt at the end of every
			  scanning/processing cycle).

[0]: Documentation/devicetree/bindings/interrupt-controller/interrupts.txt
[1]: Documentation/devicetree/bindings/gpio/gpio.txt

Example:
	&i2c1 {
		/* ... */
		cyttsp@a {
			compatible = "cypress,cyttsp-i2c";
			reg = <0xa>;
			interrupt-parent = <&gpio0>;
			interrupts = <28 0>;
			reset-gpios = <&gpio3 4 GPIO_ACTIVE_LOW>;

			touchscreen-size-x = <800>;
			touchscreen-size-y = <480>;
			touchscreen-fuzz-x = <4>;
			touchscreen-fuzz-y = <7>;

			bootloader-key = /bits/ 8 <0x01 0x02 0x03 0x04 0x05 0x06 0x07 0x08>;
			active-distance = <8>;
			active-interval-ms = <0>;
			lowpower-interval-ms = <200>;
			touch-timeout-ms = <100>;
		};

		/* ... */
	};

	&mcspi1 {
		/* ... */
		cyttsp@0 {
			compatible = "cypress,cyttsp-spi";
			spi-max-frequency = <6000000>;
			reg = <0>;
			interrupt-parent = <&gpio0>;
			interrupts = <28 0>;
			reset-gpios = <&gpio3 4 GPIO_ACTIVE_LOW>;

			touchscreen-size-x = <800>;
			touchscreen-size-y = <480>;
			touchscreen-fuzz-x = <4>;
			touchscreen-fuzz-y = <7>;

			bootloader-key = /bits/ 8 <0x01 0x02 0x03 0x04 0x05 0x06 0x07 0x08>;
			active-distance = <8>;
			active-interval-ms = <0>;
			lowpower-interval-ms = <200>;
			touch-timeout-ms = <100>;
		};

		/* ... */
	};