bindings: Documentation: add QTI audio documentation

Qualcomm Technologies, Inc. LPI GPIO controller driver

This DT bindings describes the GPIO controller driver

being added for supporting LPI (Low Power Island) TLMM

from QTI chipsets.

Following properties are for LPI GPIO controller device main node.

- compatible:

	Usage: required

	Value type: <string>

	Definition: must be "qcom,lpi-pinctrl"

- reg:

	Usage: required

	Value type: <prop-encoded-array>

	Definition: Register base of the GPIO controller and length.

- qcom,num-gpios:

	Usage: required

	Value type: <u32>

	Definition: Number of GPIOs supported by the controller.

- qcom,lpi-offset-tbl

	Usage: required

	Value type: <u32-array>

	Definition: Offset table of GPIOs supported by the controller.

- gpio-controller:

	Usage: required

	Value type: <none>

	Definition: Used to mark the device node as a GPIO controller.

- #gpio-cells:

	Usage: required

	Value type: <u32>

	Definition: Must be 2;

		    The first cell will be used to define gpio number and the

		    second denotes the flags for this gpio.

- #qcom,slew-reg:

	Usage: optional

	Value type: <prop-encoded-array>

	Definition: Register base of the slew register and length.

- #qcom,lpi-slew-offset-tbl:

	Usage: optional

	Value type: <u32-array>

	Definition: Offset table that points to each pin's shift value

		    position in bits in the slew register base for slew

		    settings.

- #qcom,lpi-slew-base-tbl:

	Usage: optional

	Value type: <u32-array>

	Definition: Table points to physical address for corresponding

		    slew registers.

Please refer to ../gpio/gpio.txt for general description of GPIO bindings.

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

common pinctrl bindings used by client devices, including the meaning of the

phrase "pin configuration node".

The pin configuration nodes act as a container for an arbitrary number of

subnodes. Each of these subnodes represents some desired configuration for a

pin or a list of pins. This configuration can include the

mux function to select on those pin(s), and various pin configuration

parameters, as listed below.

SUBNODES:

The name of each subnode is not important; all subnodes should be enumerated

and processed purely based on their content.

Each subnode only affects those parameters that are explicitly listed. In

other words, a subnode that lists a mux function but no pin configuration

parameters implies no information about any pin configuration parameters.

Similarly, a pin subnode that describes a pullup parameter implies no

information about e.g. the mux function.

The following generic properties as defined in pinctrl-bindings.txt are valid

to specify in a pin configuration subnode:

- pins:

	Usage: required

	Value type: <string-array>

	Definition: List of gpio pins affected by the properties specified in

		    this subnode.  Valid pins are: gpio0-gpio31 for LPI.

- function:

	Usage: required

	Value type: <string>

	Definition: Specify the alternative function to be configured for the

		    specified pins. Valid values are:

			"gpio",

			"func1",

			"func2",

			"func3",

			"func4",

			"func5"

- bias-disable:

	Usage: optional

	Value type: <none>

	Definition: The specified pins should be configured as no pull.

- bias-pull-down:

	Usage: optional

	Value type: <none>

	Definition: The specified pins should be configured as pull down.

- bias-bus-hold:

	Usage: optional

	Value type: <none>

	Definition: The specified pins should be configured as bus-keeper mode.

- bias-pull-up:

	Usage: optional

	Value type: <empty>

	Definition: The specified pins should be configured as pull up.

- input-enable:

	Usage: optional

	Value type: <none>

	Definition: The specified pins are put in input mode.

- output-high:

	Usage: optional

	Value type: <none>

	Definition: The specified pins are configured in output mode, driven

		    high.

- output-low:

	Usage: optional

	Value type: <none>

	Definition: The specified pins are configured in output mode, driven

		    low.

- qcom,drive-strength:

	Usage: optional

	Value type: <u32>

	Definition: Selects the drive strength for the specified pins.

- slew-rate:

	Usage: optional

	Value type: <u32>

	Definition: Selects the slew rate for the specified pins.

Example:

	lpi_tlmm: lpi_pinctrl@152c000 {

		compatible = "qcom,lpi-pinctrl";

		qcom,num-gpios = <32>;

		reg = <0x152c000 0>;

		qcom,slew-reg = <0x355a000 0x0>;

		gpio-controller;

		#gpio-cells = <2>;

		qcom,lpi-offset-tbl = <0x00000010>, <0x00000020>,

				<0x00000030>, <0x00000040>,

				<0x00000050>, <0x00000060>,

				<0x00000070>, <0x00000080>,

				<0x00000090>, <0x00000100>,

				<0x00000110>, <0x00000120>,

				<0x00000130>, <0x00000140>,

				<0x00000150>, <0x00000160>,

				<0x00000170>, <0x00000180>,

				<0x00000190>, <0x00000200>,

				<0x00000210>;

		qcom,lpi-slew-offset-tbl = <0x00000000>, <0x00000002>,

				<0x00000004>, <0x00000008>,

				<0x0000000A>, <0x0000000C>,

				<0x00000000>, <0x00000000>,

				<0x00000000>, <0x00000000>,

				<0x00000010>, <0x00000012>,

				<0x00000000>, <0x00000000>;

		hph_comp_active: hph_comp_active {

			mux {

				pins = "gpio22";

				function = "func1";

			};

			config {

				pins = "gpio22";

				output-high;

				qcom,drive-strength = <8>;

			};

		};

		hph_comp_sleep: hph_comp_sleep {

			mux {

				pins = "gpio22";

				function = "func1";

			};

			config {

				pins = "gpio22";

				qcom,drive-strength = <2>;

				slew-rate = <1>;

			};

		};

	};