[PATCH/RFC v8 02/14] Documentation: leds: Add description of LED Flash class extension

Jacek Anaszewski
2014-11-28T09:19:21Z

The documentation being added contains overall description of the
LED Flash Class and the related sysfs attributes.

Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Bryan Wu <cooloney@gmail.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
---
Documentation/leds/leds-class-flash.txt | 48 +++++++++++++++++++++++++++++++
1 file changed, 48 insertions(+)
create mode 100644 Documentation/leds/leds-class-flash.txt

diff --git a/Documentation/leds/leds-class-flash.txt b/Documentation/leds/leds-class-flash.txt
new file mode 100644
index 0000000..d68565c
--- /dev/null
+++ b/Documentation/leds/leds-class-flash.txt
@@ -0,0 +1,48 @@
+
+Flash LED handling under Linux
+==============================
+
+Some LED devices support two modes - torch and flash. The modes are
+supported by the LED class (see Documentation/leds/leds-class.txt)
+and LED Flash class respectively.
+
+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_sync_strobe - one flash device can control more than one
+ sub-led; when this atrribute is set to 1
+ the flash led will be strobed synchronously
+ with the other ones controlled by the same
+ device (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
--
1.7.9.5