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diff --git a/Documentation/leds/leds-lm3556.rst b/Documentation/leds/leds-lm3556.rst new file mode 100644 index 000000000..1ef17d7d8 --- /dev/null +++ b/Documentation/leds/leds-lm3556.rst @@ -0,0 +1,137 @@ +======================== +Kernel driver for lm3556 +======================== + +* Texas Instrument: + 1.5 A Synchronous Boost LED Flash Driver w/ High-Side Current Source +* Datasheet: http://www.national.com/ds/LM/LM3556.pdf + +Authors: + - Daniel Jeong + + Contact:Daniel Jeong(daniel.jeong-at-ti.com, gshark.jeong-at-gmail.com) + +Description +----------- +There are 3 functions in LM3556, Flash, Torch and Indicator. + +Flash Mode +^^^^^^^^^^ + +In Flash Mode, the LED current source(LED) provides 16 target current levels +from 93.75 mA to 1500 mA.The Flash currents are adjusted via the CURRENT +CONTROL REGISTER(0x09).Flash mode is activated by the ENABLE REGISTER(0x0A), +or by pulling the STROBE pin HIGH. + +LM3556 Flash can be controlled through sys/class/leds/flash/brightness file + +* if STROBE pin is enabled, below example control brightness only, and + ON / OFF will be controlled by STROBE pin. + +Flash Example: + +OFF:: + + #echo 0 > sys/class/leds/flash/brightness + +93.75 mA:: + + #echo 1 > sys/class/leds/flash/brightness + +... + +1500 mA:: + + #echo 16 > sys/class/leds/flash/brightness + +Torch Mode +^^^^^^^^^^ + +In Torch Mode, the current source(LED) is programmed via the CURRENT CONTROL +REGISTER(0x09).Torch Mode is activated by the ENABLE REGISTER(0x0A) or by the +hardware TORCH input. + +LM3556 torch can be controlled through sys/class/leds/torch/brightness file. +* if TORCH pin is enabled, below example control brightness only, +and ON / OFF will be controlled by TORCH pin. + +Torch Example: + +OFF:: + + #echo 0 > sys/class/leds/torch/brightness + +46.88 mA:: + + #echo 1 > sys/class/leds/torch/brightness + +... + +375 mA:: + + #echo 8 > sys/class/leds/torch/brightness + +Indicator Mode +^^^^^^^^^^^^^^ + +Indicator pattern can be set through sys/class/leds/indicator/pattern file, +and 4 patterns are pre-defined in indicator_pattern array. + +According to N-lank, Pulse time and N Period values, different pattern wiill +be generated.If you want new patterns for your own device, change +indicator_pattern array with your own values and INDIC_PATTERN_SIZE. + +Please refer datasheet for more detail about N-Blank, Pulse time and N Period. + +Indicator pattern example: + +pattern 0:: + + #echo 0 > sys/class/leds/indicator/pattern + +... + +pattern 3:: + + #echo 3 > sys/class/leds/indicator/pattern + +Indicator brightness can be controlled through +sys/class/leds/indicator/brightness file. + +Example: + +OFF:: + + #echo 0 > sys/class/leds/indicator/brightness + +5.86 mA:: + + #echo 1 > sys/class/leds/indicator/brightness + +... + +46.875mA:: + + #echo 8 > sys/class/leds/indicator/brightness + +Notes +----- +Driver expects it is registered using the i2c_board_info mechanism. +To register the chip at address 0x63 on specific adapter, set the platform data +according to include/linux/platform_data/leds-lm3556.h, set the i2c board info + +Example:: + + static struct i2c_board_info board_i2c_ch4[] __initdata = { + { + I2C_BOARD_INFO(LM3556_NAME, 0x63), + .platform_data = &lm3556_pdata, + }, + }; + +and register it in the platform init function + +Example:: + + board_register_i2c_bus(4, 400, + board_i2c_ch4, ARRAY_SIZE(board_i2c_ch4)); |