* ST Microelectronics STMPE Multi-Functional Device

STMPE is an MFD device which may expose the following inbuilt devices: gpio,
keypad, touchscreen, adc, pwm, rotator.

Required properties:
 - compatible			: "st,stmpe[610|801|811|1600|1601|2401|2403]"
 - reg				: I2C/SPI address of the device

Optional properties:
 - interrupts			: The interrupt outputs from the controller
 - interrupt-controller		: Marks the device node as an interrupt controller
 - wakeup-source		: Marks the input device as wakable
 - st,autosleep-timeout		: Valid entries (ms); 4, 16, 32, 64, 128, 256, 512 and 1024
 - irq-gpio			: If present, which GPIO to use for event IRQ

Optional properties for devices with touch and ADC (STMPE811|STMPE610):
 - st,sample-time		: ADC conversion time in number of clock.
					0 -> 36 clocks		4 -> 80 clocks (recommended)
					1 -> 44 clocks		5 -> 96 clocks
					2 -> 56 clocks		6 -> 124 clocks
					3 -> 64 clocks
 - st,mod-12b			: ADC Bit mode
					0 -> 10bit ADC		1 -> 12bit ADC
 - st,ref-sel			: ADC reference source
					0 -> internal		1 -> external
 - st,adc-freq			: ADC Clock speed
					0 -> 1.625 MHz		2 || 3 -> 6.5 MHz
					1 -> 3.25 MHz

Example:

	stmpe1601: stmpe1601@40 {
		compatible = "st,stmpe1601";
		reg = <0x40>;
		interrupts = <26 0x4>;
		interrupt-parent = <&gpio6>;
		interrupt-controller;

		wakeup-source;
		st,autosleep-timeout = <1024>;
	};