$FreeBSD$

GPIO configuration.
===================

1. Properties for GPIO Controllers

1.1 #gpio-cells

Property:	#gpio-cells

Value type:	<u32>

Description:	The #gpio-cells property defines the number of cells required
		to encode a gpio specifier.


1.2 gpio-controller

Property:	gpio-controller

Value type:	<empty>

Description:	The presence of a gpio-controller property defines a node as a
		GPIO controller node.


1.3 pin-count

Property:	pin-count

Value type:	<u32>

Description:	The pin-count property defines the number of GPIO pins.


1.4 Example

	GPIO: gpio@10100 {
		#gpio-cells = <3>;
		compatible = "mrvl,gpio";
		reg = <0x10100 0x20>;
		gpio-controller;
		interrupts = <6 7 8 9>;
		interrupt-parent = <&PIC>;
		pin-count = <50>
	};

2. Properties for GPIO consumer nodes.

2.1 gpios

Property:	gpios

Value type:	<prop-encoded-array> encoded as arbitrary number of GPIO
		specifiers.

Description:	The gpios property of a device node defines the GPIO or GPIOs
		that are used by the device. The value of the gpios property
		consists of an arbitrary number of GPIO specifiers.
		
		The first cell of the GPIO specifier is phandle of the node's
		parent GPIO controller and remaining cells are defined by the
		binding describing the GPIO parent, typically include
		information like pin number, direction and various flags.

Example:
		gpios = <&GPIO 0 1		/* GPIO[0]:  FLAGS */
			 &GPIO 1 2>;		/* GPIO[1]:  FLAGS */


3. GPIO controller specifier

	<phandle pin dir flags>


pin:	0-MAX				GPIO pin number.

flags:
	Available flags are listed in sys/conf.h. Following combination
	can be supported by the controller. For details please refer
	to controller's GPIO reference manual.

	GPIO_PIN_INPUT		0x0001	Input direction
	GPIO_PIN_OUTPUT		0x0002	Output direction
	GPIO_PIN_OPENDRAIN	0x0004	Open-drain output
	GPIO_PIN_OPENSOURCE	0x0008	Open-source output
	GPIO_PIN_PUSHPULL	0x0010	Push-pull output
	GPIO_PIN_TRISTATE	0x0020	Output disabled
	GPIO_PIN_PULLUP		0x0040	Internal pull-up enabled
	GPIO_PIN_PULLDOWN	0x0080	Internal pull-down enabled
	GPIO_PIN_INVIN		0x0100	Invert input
	GPIO_PIN_INVOUT		0x0200	Invert output
	GPIO_PIN_PULSATE	0x0400	Pulsate in hardware
	GPIO_PIN_IRQ_POL_EDG	0x0800	IRQ active single edge
	GPIO_PIN_IRQ_POL_DBL	0x1000	IRQ active double edge
	GPIO_PIN_IRQ_POL_LVL	0x2000	IRQ active level
	GPIO_PIN_IRQ_DEBOUNCE	0x4000	Debounce on IRQ pin

Example:
	gpios = <&GPIO 0  0x00000001	/* GPIO[0]:   IN */
		 &GPIO 1  0x00000002	/* GPIO[1]:   OUT */
		 &GPIO 2  0x00000801	/* GPIO[2]:   IN, IRQ (edge) */
		 &GPIO 3  0x00004001	/* GPIO[3]:   IN, IRQ (level) */
		 ...
		 &GPIO 10 0x00000401>;	/* GPIO[10]:  OUT, blink */