Documentation/leds/leds-class-flash.rst

2 Flash LED handling under Linux
5 Some LED devices provide two modes - torch and flash. In the LED subsystem
6 those modes are supported by LED class (see Documentation/leds/leds-class.rst)
7 and LED Flash class respectively. The torch mode related features are enabled
8 by default and the flash ones only if a driver declares it by setting
11 In order to enable the support for flash LEDs CONFIG_LEDS_CLASS_FLASH symbol
12 must be defined in the kernel config. A LED Flash class driver must be
15 Following sysfs attributes are exposed for controlling flash LED devices:
16 (see Documentation/ABI/testing/sysfs-class-led-flash)
18 	- flash_brightness
19 	- max_flash_brightness
20 	- flash_timeout
21 	- max_flash_timeout
22 	- flash_strobe
23 	- flash_fault
26 V4L2 flash wrapper for flash LEDs
36 - dev:
37 	flash device, e.g. an I2C device
38 - of_node:
40 - fled_cdev:
41 	LED flash class device to wrap
42 - iled_cdev:
43 	LED flash class device representing indicator LED associated with
45 - ops:
49 		defines the source of the flash LED strobe -
51 		a sensor, which makes it possible to synchronise the flash
55 		enum led_brightness <-> V4L2 intensity conversion in a device
56 		specific manner - they can be used for devices with non-linear
58 - config:
59 	configuration for V4L2 Flash sub-device
64 		bitmask of flash faults that the LED flash class
66 		available in <linux/led-class-flash.h>,
68 		constraints for the LED in TORCH mode
74 		determines whether the flash strobe source
78 argument - struct v4l2_flash pointer returned previously by v4l2_flash_init.
81 Please refer to drivers/leds/leds-max77693.c for an exemplary usage of the
82 v4l2 flash wrapper.
84 Once the V4L2 sub-device is registered by the driver which created the Media
85 controller device, the sub-device node acts just as a node of a native V4L2
86 flash API device would. The calls are simply routed to the LED flash API.
88 Opening the V4L2 flash sub-device makes the LED subsystem sysfs interface
89 unavailable. The interface is re-enabled after the V4L2 flash sub-device