[PATCH/RFC v6 0/6] LED / flash API integration - Documentation

@@ -0,0 +1,51 @@
+
+Flash LED handling under Linux
+==============================
+
+Some LED devices support two modes - torch and flash. In order to enable
+support for flash LEDs CONFIG_LEDS_CLASS_FLASH symbol must be defined
+in the kernel config. A flash LED driver must register in the LED subsystem
+with led_classdev_flash_register to gain flash capabilities.
+
+Following sysfs attributes are exposed for controlling flash led devices:
+
+	- flash_brightness - flash LED brightness in microamperes (RW)
+	- max_flash_brightness - maximum available flash LED brightness (RO)
+	- indicator_brightness - privacy LED brightness in microamperes (RW)
+	- max_indicator_brightness - maximum privacy LED brightness in
+				     microamperes (RO)
+	- flash_timeout - flash strobe duration in microseconds (RW)
+	- max_flash_timeout - maximum available flash strobe duration (RO)
+	- flash_strobe - flash strobe state (RW)
+	- flash_fault - bitmask of flash faults that may have occurred,
+			possible flags are:
+		* 0x01 - flash controller voltage to the flash LED has exceeded
+			 the limit specific to the flash controller
+		* 0x02 - the flash strobe was still on when the timeout set by
+			 the user has expired; not all flash controllers may
+			 set this in all such conditions
+		* 0x04 - the flash controller has overheated
+		* 0x08 - the short circuit protection of the flash controller
+			 has been triggered
+		* 0x10 - current in the LED power supply has exceeded the limit
+			 specific to the flash controller
+		* 0x40 - flash controller voltage to the flash LED has been
+			 below the minimum limit specific to the flash
+		* 0x80 - the input voltage of the flash controller is below
+			 the limit under which strobing the flash at full
+			 current will not be possible. The condition persists
+			 until this flag is no longer set
+		* 0x100 - the temperature of the LED has exceeded its allowed
+			  upper limit
+
+A LED subsystem driver can be controlled also from the level of VideoForLinux2
+subsystem. In order to enable this CONFIG_V4L2_FLASH_LED_CLASS symbol has to
+be defined in the kernel config. The driver must call v4l2_flash_init function
+to get registered in the V4L2 subsystem. On remove v4l2_flash_release function
+has to be called (see <media/v4l2-flash.h>).
+
+After proper initialization V4L2 Flash sub-device is created. The sub-device
+exposes a number of V4L2 controls. When the V4L2_CID_FLASH_LED_MODE control
+is set to V4L2_FLASH_LED_MODE_TORCH or V4L2_FLASH_LED_MODE_FLASH the
+LED subsystem sysfs interface becomes unavailable. The interface can be
+unlocked by setting the mode back to V4L2_FLASH_LED_MODE_NONE.

@@ -3,6 +3,17 @@ Common leds properties.
 Optional properties for child nodes:
 - label : The label for this LED.  If omitted, the label is
   taken from the node name (excluding the unit address).
+- iout-torch : Array of maximum intensities in microamperes of the torch
+	led currents in order from sub-led 0 to N-1, where N is the number
+	of torch sub-leds exposed by the device
+- iout-flash : Array of maximum intensities in microamperes of the flash
+	led currents in order from sub-led 0 to N-1, where N is the number
+	of flash sub-leds exposed by the device
+- iout-indicator : Array of maximum intensities in microamperes of
+	the indicator led currents in order from sub-led 0 to N-1,
+	where N is the number of indicator sub-leds exposed by the device
+- flash-timeout : timeout in microseconds after which flash led
+	is turned off
 
 - linux,default-trigger :  This parameter, if present, is a
     string defining the trigger assigned to the LED.  Current triggers are:

@@ -19,5 +30,10 @@ Examples:
 system-status {
 	label = "Status";
 	linux,default-trigger = "heartbeat";
+	iout-torch = <500 500>;
+	iout-flash = <1000 1000>;
+	iout-indicator = <100 100>;
+	flash-timeout = <1000>;
+
 	...
 };

@@ -40,6 +40,10 @@ should be inactive. For the "active-a" state the camera port A must be activated
 and the port B deactivated and for the state "active-b" it should be the other
 way around.
 
+Optional properties:
+
+- flashes - array of phandles to the available flash led devices
+
 The 'camera' node must include at least one 'fimc' child node.
 
 

@@ -166,6 +170,7 @@ Example:
 		clock-output-names = "cam_a_clkout", "cam_b_clkout";
 		pinctrl-names = "default";
 		pinctrl-0 = <&cam_port_a_clk_active>;
+		flashes = <&max77693-flash>, <&aat1290>;
 		status = "okay";
 		#address-cells = <1>;
 		#size-cells = <1>;

@@ -27,6 +27,55 @@ Optional properties:
 
 	[*] refer Documentation/devicetree/bindings/regulator/regulator.txt
 
+Optional node:
+- led-flash : the LED submodule device node
+
+Required properties of "led-flash" node:
+- compatible : must be "maxim,max77693-flash"
+- maxim,num-leds : number of connected leds
+	Possible values: 1 or 2.
+- maxim,fleds : array of current outputs in order: fled1, fled2
+	Note: both current outputs can be connected to a single led
+	Possible values:
+		0 - the output is left disconnected,
+		1 - a diode is connected to the output.
+
+Optional properties of "led-flash" node:
+- maxim,boost-mode :
+	In boost mode the device can produce up to 1.2A of total current
+	on both outputs. The maximum current on each output is reduced
+	to 625mA then. If maxim,num-leds == <2> boost must be enabled
+	(it defaults to 1 if not set):
+	Possible values:
+		0 - no boost,
+		1 - adaptive mode,
+		2 - fixed mode.
+- iout-torch : Array of maximum intensities in microamperes of the torch
+	led currents in order: fled1, fled2.
+		15625 - 250000
+- iout-flash : Array of maximum intensities in microamperes of the flash
+	led currents in order: fled1, fled2.
+	Range:
+		15625 - 1000000 (max 625000 if boost mode is enabled)
+- flash-timeout : timeout in microseconds after which flash led
+		  is turned off
+	Range:
+		62500 - 1000000
+- maxim,trigger : Array of flags indicating which trigger can activate given led
+	in order: fled1, fled2
+	Possible flag values (can be combined):
+		1 - FLASH pin of the chip,
+		2 - TORCH pin of the chip,
+		4 - software via I2C command.
+- maxim,trigger-type : Array of trigger types in order: flash, torch.
+	Possible trigger types:
+		0 - Rising edge of the signal triggers the flash/torch,
+		1 - Signal level controls duration of the flash/torch.
+- maxim,boost-vout : Output voltage of the boost module in millivolts.
+- maxim,vsys-min : Low input voltage level in millivolts. Flash is not fired
+	if chip estimates that system voltage could drop below this level due
+	to flash power consumption.
+
 Example:
 	max77693@66 {
 		compatible = "maxim,max77693";

@@ -52,4 +101,17 @@ Example:
 					regulator-boot-on;
 			};
 		};
+		led_flash: led-flash {
+			compatible = "maxim,max77693-flash";
+			iout-torch = <500000 0>;
+			iout-flash = <1250000 0>;
+			flash-timeout = <1000000 1000000>;
+			maxim,num-leds = <1>;
+			maxim,fleds = <1 1>;
+			maxim,trigger = <7 7>;
+			maxim,trigger-type = <0 1>;
+			maxim,boost-mode = <1>;
+			maxim,boost-vout = <5000>;
+			maxim,vsys-min = <2400>;
+		};
 	};

@@ -117,6 +117,7 @@ renesas	Renesas Electronics Corporation
 ricoh	Ricoh Co. Ltd.
 rockchip	Fuzhou Rockchip Electronics Co., Ltd
 samsung	Samsung Semiconductor
+skyworks	Skyworks Solutions, Inc.
 sbs	Smart Battery System
 schindler	Schindler
 seagate	Seagate Technology PLC

@@ -0,0 +1,17 @@
+* Skyworks Solutions, Inc. AAT1290 Current Regulator for Flash LEDs
+
+Required properties:
+
+- compatible : should be "skyworks,aat1290"
+- gpios : two gpio pins in order FLEN, EN/SET
+- skyworks,flash-timeout : maximum flash timeout in microseconds -
+			   it can be calculated using following formula:
+			   T = 8.82 * 10^9 * Ct
+
+Example:
+
+flash_led: flash-led {
+	compatible = "skyworks,aat1290";
+	gpios = <&gpj1 1 0>, <&gpj1 2 0>;
+	flash-timeout = <1940000>;
+}