Qualcomm Technologies QPNP WLED

QPNP (Qualcomm Technologies Plug N Play) WLED (White Light
Emitting Diode) driver is used for controlling display
backlight that is part of PMIC on Qualcomm Technologies
reference platforms. The PMIC is connected to the host
processor via SPMI bus.

Required properties:
- compatible		: should be "qcom,qpnp-wled"
- reg			: base address and size for wled modules
- reg-names		: names associated with base addresses. It
			should be "qpnp-wled-ctrl-base", "qpnp-wled-sink-base",
			"qpnp-wled-ibb-base", "qpnp-wled-lab-base".
- qcom,pmic-revid	: phandle of PMIC revid module. This is used to
			  identify the PMIC subtype.

Optional properties for WLED:
 - interrupts		: Specifies the interrupts associated with WLED. The available
			  interrupts are over voltage protection(ovp) and short circuit(sc).
			  The values for ovp and sc are <0x3 0xd8 0x1> and <0x3 0xd8 0x2>.
 - interrupt-names	: Specify the interrupt names associated with interrupts. Must be
			  one of "ovp-irq" or "sc-irq"
- linux,name		: name of the wled. default is "wled".
- linux,default-trigger	: trigger for the backlight. default is NONE.
- qcom,fdbk-output	: string feedback current output for wled module. The accepted values
			  are "wled1", "wled2", "wled3", "wled4" and "auto". default is "auto".
- qcom,vref-uv		: maximum reference voltage in uV.
			  For pmi8994/8952/8996, supported values are from 300000 to 675000
			  with a step size of 25000, the default value is 350000.
			  For pmi8998/pm660l, supported values are from 60000 to 397500
			  with a step size of 22500, the default value is 127500.
- qcom,switch-freq-khz	: switch frequency in khz. default is 800.
- qcom,ovp-mv		: Over voltage protection threshold in mV. Default is
			  29500. Supported values are:
			  - 31000, 29500, 19400, 17800 for pmi8994/8952/8996.
			  - 31100, 29600, 19600, 18100 for pmi8998/pm660l.
			  Should only be used if qcom,disp-type-amoled is not
			  specified.
- qcom,ilim-ma		: Current limit threshold in mA.
			  For pmi8994/8952/8996, default value for LCD is 980mA
			  and AMOLED is 385mA.
			  Supported values are:
			  - 105, 385, 660, 980, 1150, 1420, 1700, 1980.
			  For pmi8998/pm660l, default value for LCD is
			  970mA and AMOLED is 620mA.
			  Supported values are:
			  - 105, 280, 450, 620, 970, 1150, 1300, 1500.
- qcom,boost-duty-ns	: maximum boost duty cycle in ns. default is 104.
- qcom,mod-freq-khz	: modulation frequency in khz. default is 9600.
- qcom,dim-mode		: dimming mode. supporting dimming modes are "analog",
			  "digital", and "hybrid". default is "hybrid".
- qcom,hyb-thres	: threshold value when used in hybrid mode. It represents the
			  percentage of brightntess at which dimming mode is switched
			  from "digital" to "analog". the default value is 6.25%. as the
			  floating point cannot be represented directly, the value is
			  multiplied by 100. so the default is 625.
- qcom,sync-dly-us	: delay for current sync in us. default is 400.
- qcom,fs-curr-ua	: maximum full scale current in ua. default is 25000.
- qcom,en-9b-dim-res	: boolean, specify if 9-bit dim resultion is needed. otherwise 12-bit is used.
- qcom,en-phase-stag	: boolean, specify if phase staggering is needed.
- qcom,en-cabc		: boolean, specify if cabc (content adaptive backlight control) is needed.
- qcom,disp-type-amoled	: specify if the display is amoled
- qcom,led-strings-list	: Wled module has four strings of leds numbered from 0 to 3. each string of leds
			  are operated individually. specify the list of strings used by the device.
			  any combination of led strings can be used. default value is [00 01 02 03]
- qcom,en-ext-pfet-sc-pro : Specify if external pfet short circuit protection is needed
- qcom,cons-sync-write-delay-us : Specify in 'us' the duration of delay between two consecutive writes to
				  SYNC register.
- qcom,sc-debounce-cycles	: debounce time for short circuit detection
- qcom,loop-ea-gm	: control the gm for gm stage in control loop. default is 3.
- qcom,loop-auto-gm-en	: A boolean property to specify if auto gm is enabled.
- qcom,loop-auto-gm-thresh	: Specify auto gm threshold if "loop-auto-gm-en" is defined.
				  Supported values are: 0 - 3.
- qcom,lcd-auto-pfm-thresh	: Specify the auto-pfm threshold, if the headroom voltage level
				  falls below this threshold and auto PFM is enabled, boost
				  controller will enter into PFM mode automatically.
- qcom,lcd-psm-ctrl	: A boolean property to specify if PSM needs to be
			  controlled dynamically when WLED module is enabled
			  or disabled.
- qcom,auto-calibration-enable : A boolean property which enables auto-calibration
				 of the WLED sink configuration.
- qcom,wled-brightness-map	: Array of brightness map codes of size 256.
				  These codes will be mapped to the brightness
				  level requested in the scale of 0-4095. Code
				  entry is of 16 bit size.
- qcom,wled-stepper-en	: A boolean property to specify if stepper algorithm
			  needs to be enabled. This needs the brightness map
			  table to be specified.

Optional properties if 'qcom,disp-type-amoled' is mentioned in DT:
- qcom,loop-comp-res-kohm	: control to select the compensation resistor in kohm. default is 320.
- qcom,vref-psm-mv	: reference psm voltage in mv. default for amoled is 450.
- qcom,avdd-mode-spmi: Boolean property to enable AMOLED_VOUT programming via SPMI. If not specified,
			AMOLED_VOUT is programmed via S-wire. This can be specified only for newer
			PMICs like pmi8998/pm660l.
- qcom,avdd-target-voltage-mv: The voltage required for AMOLED_VOUT. Accepted values are in the range
				of 5650 to 7900 in steps of 150. Default value is 7600. Unit is in mV.
				For old revisions, accepted values are: 7900, 7600, 7300, 6400, 6100,
				5800.

Example:
	qcom,leds@d800 {
		compatible = "qcom,qpnp-wled";
		reg = <0xd800 0x100>,
			<0xd900 0x100>,
			<0xdc00 0x100>,
			<0xde00 0x100>;
		reg-names = "qpnp-wled-ctrl-base",
				"qpnp-wled-sink-base",
				"qpnp-wled-ibb-base",
				"qpnp-wled-lab-base";
		interrupts = <0x3 0xd8 0x2>;
		interrupt-names = "sc-irq";
		status = "okay";
		linux,name = "wled";
		linux,default-trigger = "bkl-trigger";
		qcom,fdbk-output = "auto";
		qcom,vref-uv = <350000>;
		qcom,switch-freq-khz = <800>;
		qcom,ovp-mv = <29500>;
		qcom,ilim-ma = <980>;
		qcom,boost-duty-ns = <26>;
		qcom,mod-freq-khz = <9600>;
		qcom,dim-mode = "hybrid";
		qcom,dim-method = "linear";
		qcom,hyb-thres = <625>;
		qcom,sync-dly-us = <800>;
		qcom,fs-curr-ua = <16000>;
		qcom,en-phase-stag;
		qcom,led-strings-list = [00 01 02 03];
		qcom,en-ext-pfet-sc-pro;
		qcom,wled-brightness-map = /bits/ 16  <0 . . 4095>;
	};