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author | G.Shark Jeong <gshark.jeong@gmail.com> | 2012-06-22 08:12:06 +0800 |
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committer | Bryan Wu <bryan.wu@canonical.com> | 2012-07-24 07:52:35 +0800 |
commit | 32abb4788d3fff69fa242c7850e39ec1418df4f4 (patch) | |
tree | 26441f5ebda1a77b7f0f72fb6b487634b2e623c0 /Documentation/leds/leds-lm3556.txt | |
parent | 1522d02e275332080ec27e268edc29c79c6f5e0c (diff) | |
download | linux-32abb4788d3fff69fa242c7850e39ec1418df4f4.tar.bz2 |
leds: Add LED driver for lm3556 chip
LM3556 :
The LM3556 is a 4 MHz fixed-frequency synchronous boost
converter plus 1.5A constant current driver for a high-current white LED.
Datasheet: www.national.com/ds/LM/LM3556.pdf
Tested on OMAP4430
(bryan.wu@canonical.com: use module_i2c_driver() rather than
lm3556_init/lm3556_exit for code simplicity; fixed some typo
pointed out by Rob Landley)
Signed-off-by: G.Shark Jeong <gshark.jeong@gmail.com>
Reviewed-by: Axel Lin <axel.lin@gmail.com>
Reviewed-by: Kim, Milo <Milo.Kim@ti.com>
Acked-by: Rob Landley <rob@landley.net>
Signed-off-by: Bryan Wu <bryan.wu@canonical.com>
Diffstat (limited to 'Documentation/leds/leds-lm3556.txt')
-rw-r--r-- | Documentation/leds/leds-lm3556.txt | 85 |
1 files changed, 85 insertions, 0 deletions
diff --git a/Documentation/leds/leds-lm3556.txt b/Documentation/leds/leds-lm3556.txt new file mode 100644 index 000000000000..d9eb91b51913 --- /dev/null +++ b/Documentation/leds/leds-lm3556.txt @@ -0,0 +1,85 @@ +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 __initdata board_i2c_ch4[] = { + { + 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)); |