dt-bindings: Add Oxford Semiconductor OXNAS pinctrl and gpio bindings

* Oxford Semiconductor OXNAS SoC GPIO Controller

Please refer to gpio.txt for generic information regarding GPIO bindings.

Required properties:

 - compatible: "oxsemi,ox810se-gpio"

 - reg: Base address and length for the device.

 - interrupts: The port interrupt shared by all pins.

 - gpio-controller: Marks the port as GPIO controller.

 - #gpio-cells: Two. The first cell is the pin number and

   the second cell is used to specify the gpio polarity as defined in

   defined in <dt-bindings/gpio/gpio.h>:

      0 = GPIO_ACTIVE_HIGH

      1 = GPIO_ACTIVE_LOW

 - interrupt-controller: Marks the device node as an interrupt controller.

 - #interrupt-cells: Two. The first cell is the GPIO number and second cell

   is used to specify the trigger type as defined in

   <dt-bindings/interrupt-controller/irq.h>:

      IRQ_TYPE_EDGE_RISING

      IRQ_TYPE_EDGE_FALLING

      IRQ_TYPE_EDGE_BOTH

 - gpio-ranges: Interaction with the PINCTRL subsystem, it also specifies the

   gpio base and count, should be in the format of numeric-gpio-range as

   specified in the gpio.txt file.

Example:

gpio0: gpio@0 {

	compatible = "oxsemi,ox810se-gpio";

	reg = <0x000000 0x100000>;

	interrupts = <21>;

	#gpio-cells = <2>;

	gpio-controller;

	interrupt-controller;

	#interrupt-cells = <2>;

	gpio-ranges = <&pinctrl 0 0 32>;

};

keys {

	...

	button-esc {

		label = "ESC";

		linux,code = <1>;

		gpios = <&gpio0 12 0>;

	};

};

* Oxford Semiconductor OXNAS SoC Family Pin Controller

Please refer to pinctrl-bindings.txt, ../gpio/gpio.txt, and

../interrupt-controller/interrupts.txt for generic information regarding

pin controller, GPIO, and interrupt bindings.

OXNAS 'pin configuration node' is a node of a group of pins which can be

used for a specific device or function. This node represents configurations of

pins, optional function, and optional mux related configuration.

Required properties for pin controller node:

 - compatible: "oxsemi,ox810se-pinctrl"

 - oxsemi,sys-ctrl: a phandle to the system controller syscon node

Required properties for pin configuration sub-nodes:

 - pins: List of pins to which the configuration applies.

Optional properties for pin configuration sub-nodes:

----------------------------------------------------

 - function: Mux function for the specified pins.

 - bias-pull-up: Enable weak pull-up.

Example:

pinctrl: pinctrl {

	compatible = "oxsemi,ox810se-pinctrl";

	/* Regmap for sys registers */

	oxsemi,sys-ctrl = <&sys>;

	pinctrl_uart2: pinctrl_uart2 {

		uart2a {

			pins = "gpio31";

			function = "fct3";

		};

		uart2b {

			pins = "gpio32";

			function = "fct3";

		};

	};

};

uart2: serial@900000 {

	compatible = "ns16550a";

	reg = <0x900000 0x100000>;

	clocks = <&sysclk>;

	interrupts = <29>;

	reg-shift = <0>;

	fifo-size = <16>;

	reg-io-width = <1>;

	current-speed = <115200>;

	no-loopback-test;

	status = "disabled";

	resets = <&reset 22>;

	pinctrl-names = "default";

	pinctrl-0 = <&pinctrl_uart2>;

};