path: root/Documentation/leds
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authorG.Shark Jeong <gshark.jeong@gmail.com>2012-06-22 08:12:06 +0800
committerBryan Wu <bryan.wu@canonical.com>2012-07-24 07:52:35 +0800
commit32abb4788d3fff69fa242c7850e39ec1418df4f4 (patch)
tree26441f5ebda1a77b7f0f72fb6b487634b2e623c0 /Documentation/leds
parent1522d02e275332080ec27e268edc29c79c6f5e0c (diff)
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')
2 files changed, 87 insertions, 0 deletions
diff --git a/Documentation/leds/00-INDEX b/Documentation/leds/00-INDEX
index 29f481df32c..5fefe374892 100644
--- a/Documentation/leds/00-INDEX
+++ b/Documentation/leds/00-INDEX
@@ -6,3 +6,5 @@ leds-lp5521.txt
- notes on how to use the leds-lp5521 driver.
- notes on how to use the leds-lp5523 driver.
+ - notes on how to use the leds-lm3556 driver.
diff --git a/Documentation/leds/leds-lm3556.txt b/Documentation/leds/leds-lm3556.txt
new file mode 100644
index 00000000000..d9eb91b5191
--- /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
+ Daniel Jeong
+ Contact:Daniel Jeong(daniel.jeong-at-ti.com, gshark.jeong-at-gmail.com)
+There are 3 functions in LM3556, Flash, Torch and Indicator.
+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
+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 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.
+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
+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
+ 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
+ board_register_i2c_bus(4, 400,
+ board_i2c_ch4, ARRAY_SIZE(board_i2c_ch4));