pinctrl: dt-bindings: Add pinctrl bindings for mt65xx/mt81xx.

* Mediatek MT65XX Pin Controller

The Mediatek's Pin controller is used to control SoC pins.

Required properties:

- compatible: value should be either of the following.

    (a) "mediatek,mt8135-pinctrl", compatible with mt8135 pinctrl.

- mediatek,pctl-regmap: Should be a phandle of the syscfg node.

- pins-are-numbered: Specify the subnodes are using numbered pinmux to

  specify pins.

- gpio-controller : Marks the device node as a gpio controller.

- #gpio-cells: number of cells in GPIO specifier. Since the generic GPIO

  binding is used, the amount of cells must be specified as 2. See the below

  mentioned gpio binding representation for description of particular cells.

	Eg: <&pio 6 0>

	<[phandle of the gpio controller node]

	[line number within the gpio controller]

	[flags]>

	Values for gpio specifier:

	- Line number: is a value between 0 to 202.

	- Flags:  bit field of flags, as defined in <dt-bindings/gpio/gpio.h>.

            Only the following flags are supported:

            0 - GPIO_ACTIVE_HIGH

            1 - GPIO_ACTIVE_LOW

- reg: physicall address base for EINT registers

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

- #interrupt-cells: Should be two.

- interrupts : The interrupt outputs from the controller.

Please refer to pinctrl-bindings.txt in this directory for details of the

common pinctrl bindings used by client devices.

Subnode format

A pinctrl node should contain at least one subnodes representing the

pinctrl groups available on the machine. Each subnode will list the

pins it needs, and how they should be configured, with regard to muxer

configuration, pullups, drive strength, input enable/disable and input schmitt.

    node {

	pinmux = <PIN_NUMBER_PINMUX>;

	GENERIC_PINCONFIG;

    };

Required properties:

- pinmux: integer array, represents gpio pin number and mux setting.

    Supported pin number and mux varies for different SoCs, and are defined

    as macros in boot/dts/<soc>-pinfunc.h directly.

Optional properties:

- GENERIC_PINCONFIG: is the generic pinconfig options to use, bias-disable,

    bias-pull-down, bias-pull-up, input-enable, input-disable, output-low, output-high,

    input-schmitt-enable, input-schmitt-disable and drive-strength are valid.

    Some special pins have extra pull up strength, there are R0 and R1 pull-up

    resistors available, but for user, it's only need to set R1R0 as 00, 01, 10 or 11.

    So when config bias-pull-up, it support arguments for those special pins.

    Some macros have been defined for this usage, such as MTK_PUPD_SET_R1R0_00.

    See dt-bindings/pinctrl/mt65xx.h.

    When config drive-strength, it can support some arguments, such as

    MTK_DRIVE_4mA, MTK_DRIVE_6mA, etc. See dt-bindings/pinctrl/mt65xx.h.

Examples:

#include "mt8135-pinfunc.h"

...

{

	syscfg_pctl_a: syscfg_pctl_a@10005000 {

		compatible = "mediatek,mt8135-pctl-a-syscfg", "syscon";

		reg = <0 0x10005000 0 0x1000>;

	};

	syscfg_pctl_b: syscfg_pctl_b@1020C020 {

		compatible = "mediatek,mt8135-pctl-b-syscfg", "syscon";

		reg = <0 0x1020C020 0 0x1000>;

	};

	pinctrl@01c20800 {

		compatible = "mediatek,mt8135-pinctrl";

		reg = <0 0x1000B000 0 0x1000>;

		mediatek,pctl-regmap = <&syscfg_pctl_a &syscfg_pctl_b>;

		pins-are-numbered;

		gpio-controller;

		#gpio-cells = <2>;

		interrupt-controller;

		#interrupt-cells = <2>;

		interrupts = <GIC_SPI 116 IRQ_TYPE_LEVEL_HIGH>,

				<GIC_SPI 117 IRQ_TYPE_LEVEL_HIGH>,

				<GIC_SPI 118 IRQ_TYPE_LEVEL_HIGH>;

		i2c0_pins_a: i2c0@0 {

			pins1 {

				pinmux = <MT8135_PIN_100_SDA0__FUNC_SDA0>,

					 <MT8135_PIN_101_SCL0__FUNC_SCL0>;

				bias-disable;

			};

		};

		i2c1_pins_a: i2c1@0 {

			pins {

				pinmux = <MT8135_PIN_195_SDA1__FUNC_SDA1>,

					 <MT8135_PIN_196_SCL1__FUNC_SCL1>;

				bias-pull-up = <55>;

			};

		};

		i2c2_pins_a: i2c2@0 {

			pins1 {

				pinmux = <MT8135_PIN_193_SDA2__FUNC_SDA2>;

				bias-pull-down;

			};

			pins2 {

				pinmux = <MT8135_PIN_49_WATCHDOG__FUNC_GPIO49>;

				bias-pull-up;

			};

		};

		i2c3_pins_a: i2c3@0 {

			pins1 {

				pinmux = <MT8135_PIN_40_DAC_CLK__FUNC_GPIO40>,

					 <MT8135_PIN_41_DAC_WS__FUNC_GPIO41>;

				bias-pull-up = <55>;

			};

			pins2 {

				pinmux = <MT8135_PIN_35_SCL3__FUNC_SCL3>,

					 <MT8135_PIN_36_SDA3__FUNC_SDA3>;

				output-low;

				bias-pull-up = <55>;

			};

			pins3 {

				pinmux = <MT8135_PIN_57_JTCK__FUNC_GPIO57>,

					 <MT8135_PIN_60_JTDI__FUNC_JTDI>;

				drive-strength = <32>;

			};

		};

		...

	}

};