dt-bindings: pinctrl: Add DT bindings for Spreadtrum SC9860

* Spreadtrum Pin Controller

The Spreadtrum pin controller are organized in 3 blocks (types).

The first block comprises some global control registers, and each

register contains several bit fields with one bit or several bits

to configure for some global common configuration, such as domain

pad driving level, system control select and so on ("domain pad

driving level": One pin can output 3.0v or 1.8v, depending on the

related domain pad driving selection, if the related domain pad

slect 3.0v, then the pin can output 3.0v. "system control" is used

to choose one function (like: UART0) for which system, since we

have several systems (AP/CP/CM4) on one SoC.).

There are too much various configuration that we can not list all

of them, so we can not make every Spreadtrum-special configuration

as one generic configuration, and maybe it will add more strange

global configuration in future. Then we add one "sprd,control" to

set these various global control configuration, and we need use

magic number for this property.

Moreover we recognise every fields comprising one bit or several

bits in one global control register as one pin, thus we should

record every pin's bit offset, bit width and register offset to

configure this field (pin).

The second block comprises some common registers which have unified

register definition, and each register described one pin is used

to configure the pin sleep mode, function select and sleep related

configuration.

Now we have 4 systems for sleep mode on SC9860 SoC: AP system,

PUBCP system, TGLDSP system and AGDSP system. And the pin sleep

related configuration are:

- input-enable

- input-disable

- output-high

- output-low

- bias-pull-up

- bias-pull-down

In some situation we need set the pin sleep mode and pin sleep related

configuration, to set the pin sleep related configuration automatically

by hardware when the system specified by sleep mode goes into deep

sleep mode. For example, if we set the pin sleep mode as PUBCP_SLEEP

and set the pin sleep related configuration as "input-enable", which

means when PUBCP system goes into deep sleep mode, this pin will be set

input enable automatically.

Moreover we can not use the "sleep" state, since some systems (like:

PUBCP system) do not run linux kernel OS (only AP system run linux

kernel on SC9860 platform), then we can not select "sleep" state

when the PUBCP system goes into deep sleep mode. Thus we introduce

"sprd,sleep-mode" property to set pin sleep mode.

The last block comprises some misc registers which also have unified

register definition, and each register described one pin is used to

configure drive strength, pull up/down and so on. Especially for pull

up, we have two kind pull up resistor: 20K and 4.7K.

Required properties for Spreadtrum pin controller:

- compatible: "sprd,<soc>-pinctrl"

  Please refer to each sprd,<soc>-pinctrl.txt binding doc for supported SoCs.

- reg: The register address of pin controller device.

- pins : An array of pin names.

Optional properties:

- function: Specified the function name.

- drive-strength: Drive strength in mA.

- input-schmitt-disable: Enable schmitt-trigger mode.

- input-schmitt-enable: Disable schmitt-trigger mode.

- bias-disable: Disable pin bias.

- bias-pull-down: Pull down on pin.

- bias-pull-up: Pull up on pin.

- input-enable: Enable pin input.

- input-disable: Enable pin output.

- output-high: Set the pin as an output level high.

- output-low: Set the pin as an output level low.

- sleep-hardware-state: Indicate these configs in this state are sleep related.

- sprd,control: Control values referring to databook for global control pins.

- sprd,sleep-mode: Sleep mode selection.

Please refer to each sprd,<soc>-pinctrl.txt binding doc for supported values.

* Spreadtrum SC9860 Pin Controller

Please refer to sprd,pinctrl.txt in this directory for common binding part

and usage.

Required properties:

- compatible: Must be "sprd,sc9860-pinctrl".

- reg: The register address of pin controller device.

- pins : An array of strings, each string containing the name of a pin.

Optional properties:

- function: A string containing the name of the function, values must be

  one of: "func1", "func2", "func3" and "func4".

- drive-strength: Drive strength in mA. Supported values: 2, 4, 6, 8, 10,

  12, 14, 16, 20, 21, 24, 25, 27, 29, 31 and 33.

- input-schmitt-disable: Enable schmitt-trigger mode.

- input-schmitt-enable: Disable schmitt-trigger mode.

- bias-disable: Disable pin bias.

- bias-pull-down: Pull down on pin.

- bias-pull-up: Pull up on pin. Supported values: 20000 for pull-up resistor

  is 20K and 4700 for pull-up resistor is 4.7K.

- input-enable: Enable pin input.

- input-disable: Enable pin output.

- output-high: Set the pin as an output level high.

- output-low: Set the pin as an output level low.

- sleep-hardware-state: Indicate these configs in this state are sleep related.

- sprd,control: Control values referring to databook for global control pins.

- sprd,sleep-mode: Choose the pin sleep mode, and supported values are:

  AP_SLEEP, PUBCP_SLEEP, TGLDSP_SLEEP and AGDSP_SLEEP.

Pin sleep mode definition:

enum pin_sleep_mode {

	AP_SLEEP = BIT(0),

	PUBCP_SLEEP = BIT(1),

	TGLDSP_SLEEP = BIT(2),

	AGDSP_SLEEP = BIT(3),

};

Example:

pin_controller: pinctrl@402a0000 {

	compatible = "sprd,sc9860-pinctrl";

	reg = <0x402a0000 0x10000>;

	grp1: sd0 {

		pins = "SC9860_VIO_SD2_IRTE", "SC9860_VIO_SD0_IRTE";

		sprd,control = <0x1>;

	};

	grp2: rfctl_33 {

		pins = "SC9860_RFCTL33";

		function = "func2";

		sprd,sleep-mode = <AP_SLEEP | PUBCP_SLEEP>;

		grp2_sleep_mode: rfctl_33_sleep {

			pins = "SC9860_RFCTL33";

			sleep-hardware-state;

			output-low;

		}

	};

	grp3: rfctl_misc_20 {

		pins = "SC9860_RFCTL20_MISC";

		drive-strength = <10>;

		bias-pull-up = <4700>;

		grp3_sleep_mode: rfctl_misc_sleep {

			pins = "SC9860_RFCTL20_MISC";

			sleep-hardware-state;

			bias-pull-up;

		}

	};

};