QPNP AMOLED Triple power supply regulator devices

QPNP OLEDB module provides AVDD voltage rail output for bias and QPNP AB/IBB
module provides ELVDD/ELVSS voltage rail output to power up AMOLED panels.

For PM8150A, allowed voltage levels are as below:
AVDD - Programmable output from 5 V to 8 V.
ELVDD  - Programmable output from 4.6 V to 5.2 V.
ELVSS  - Programmable output from -0.8 V to -5.4 V.

For PM8350B, allowed voltage levels are as below:
AVDD - Programmable output from 5 V to 8 V.
ELVDD  - Programmable output from 4.6 V to 5.2 V.
ELVSS  - Programmable output from -1.4 V to -6.6 V.

This document describes the bindings for AMOLED regulator devices.

=======================
Required Node Structure
=======================

AMOLED regulator device must be described in two level of device nodes.

- compatible:
	Usage:      required
	Value type: <string>
	Definition: should be "qcom,qpnp-amoled-regulator"

==========================================
Second Level Nodes - OLEDB/AB/IBB specific
==========================================

Subnode common properties for OLEDB and AB/IBB regulator devices.

- reg:
	Usage:      required
	Value type: <prop-encoded-array>
	Definition: Register base for OLEDB, AB and IBB modules which are
		    represented as child nodes.

- reg-names:
	Usage:      required
	Value type: <string>
	Definition: The name of the register defined in the reg property.

- regulator-name:
	Usage:      required
	Value type: <string>
	Definition: A string used to describe the regulator.

- regulator-min-microvolt:
	Usage:      required
	Value type: <u32>
	Definition: Minimum voltage (in uV) supported by the regulator.

- regulator-max-microvolt:
	Usage:      required
	Value type: <u32>
	Definition: Maximum voltage (in uV) supported by the regulator.

- qcom,swire-control:
	Usage:	    optional
	Value type: <empty>
	Definition: A boolean property to specify that the regulator output is
		    controlled by SWIRE signal. When this is specified, output
		    voltage of the regulator is not controlled by SW.

- qcom,aod-pd-control:
	Usage:      optional
	Value type: <empty>
	Definition: A boolean property to specify that the pull down control
		    for AB/IBB needs to be configured during AOD mode.

- qcom,ibb-single-phase:
	Usage:      optional
	Value type: <empty>
	Definition: A boolean property to specify that IBB regulator needs to
		    be configured in single phase always.

- qcom,ibb-spur-mitigation-level
	Usage:      optional
	Value type: <u32>
	Definition: IBB spur mitigation level selection options.
			0 = IBB spur mitigation disabled
			1 = IBB spur mitigation enabled without SQM mode
			2 = IBB spur mitigation enabled with SQM mode.

- qcom,ibb-spur-sqm-timer-ms
	Usage:      optional
	Value type: <u32>
	Definition: A property to specify delay in ms for the SQM mode timeout.
		    The is the time HW stays in SQM mode before re-evaluating the
		    exit condition. This property is only valid when
		    qcom,ibb-spur-mitigation-level is set to 2
		    (IBB spur mitigation enabled with SQM mode). If not defined,
		    1000ms will be used by default as SQM mode timeout delay.
		    The range of values supported is from 100ms to 10000ms.
		    Also, this value is stored in main PMIC's SDAM and an NVMEM cell
		    referring to this SDAM location must be defined if
		    this property is used.

- qcom,ibb-spur-2khz-step-size
	Usage:      optional
	Value type: <empty>
	Definition: A boolean property to specify 2khz step size, instead of the 1khz.
		    if defined this doubles the frequency selection range from
		    1-248khz to 2-496khz, for all the frequency band thresholds.


-qcom,ibb-spur-freq-thresholds
	Usage:      optional
	Value type: <prop-encoded-array>
	Definition: Property to specify a range of thresholds for 3 frequency bands
		    with each tuple representing a high and low threshold. Valid
		    ranges are from 1-248khz and 2-496khz(step size 2khz).
		    To disable a frequency band set both High and Low
                    thresholds to (-1).

Example:

amoled: oledb@e000 {
	compatible = "qcom,qpnp-amoled-regulator";

	/*
	 * Optional NVMEM cell property, needed only if IBB spur
	 * mitigation feature is enabled and SQM timer value
	 * is defined.
	 */
	nvmem-cell-names ="ibb_spur_sqm_timer";
	nvmem-cells = <&ibb_spur_sqm_timer>;

	oledb_vreg: oledb@e000 {
		reg = <0xe000>;
		reg-names = "oledb_base";
		regulator-name = "oledb_vreg";
		regulator-min-microvolt = <5000000>;
		regulator-max-microvolt = <8000000>;
		qcom,swire-control;
	};

	ab_vreg: ab@de00 {
		reg = <0xde00>;
		reg-names = "ab_base";
		regulator-name = "ab_vreg";
		regulator-min-microvolt = <4600000>;
		regulator-max-microvolt = <5200000>;
		qcom,swire-control;
		qcom,aod-pd-control;
	};

	ibb_vreg: ibb@dc00 {
		reg = <0xdc00>;
		reg-names = "ibb_base";
		regulator-name = "ibb_vreg";
		regulator-min-microvolt = <800000>;
		regulator-max-microvolt = <5400000>;
		qcom,swire-control;
		qcom,aod-pd-control;

		/* IBB spur mitigation properties (optional feature) */
		qcom,ibb-spur-mitigation-level = <0>; /* Spur mitigation disabled(0) */
		qcom,ibb-spur-sqm-timer-ms = <1000>;
		qcom,ibb-spur-2khz-step-size;
		qcom,ibb-spur-freq-thresholds = <100 120>,
						<150 170>,
						<(-1) (-1)>;
	};
};