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G.Shark Jeong32abb472012-06-22 08:12:06 +08001Kernel driver for lm3556
2========================
3
4*Texas Instrument:
5 1.5 A Synchronous Boost LED Flash Driver w/ High-Side Current Source
6* Datasheet: http://www.national.com/ds/LM/LM3556.pdf
7
8Authors:
9 Daniel Jeong
10 Contact:Daniel Jeong(daniel.jeong-at-ti.com, gshark.jeong-at-gmail.com)
11
12Description
13-----------
14There are 3 functions in LM3556, Flash, Torch and Indicator.
15
16FLASH MODE
17In Flash Mode, the LED current source(LED) provides 16 target current levels
18from 93.75 mA to 1500 mA.The Flash currents are adjusted via the CURRENT
19CONTROL REGISTER(0x09).Flash mode is activated by the ENABLE REGISTER(0x0A),
20or by pulling the STROBE pin HIGH.
21LM3556 Flash can be controlled through sys/class/leds/flash/brightness file
22* if STROBE pin is enabled, below example control brightness only, and
23ON / OFF will be controlled by STROBE pin.
24
25Flash Example:
26OFF : #echo 0 > sys/class/leds/flash/brightness
2793.75 mA: #echo 1 > sys/class/leds/flash/brightness
28... .....
291500 mA: #echo 16 > sys/class/leds/flash/brightness
30
31TORCH MODE
32In Torch Mode, the current source(LED) is programmed via the CURRENT CONTROL
33REGISTER(0x09).Torch Mode is activated by the ENABLE REGISTER(0x0A) or by the
34hardware TORCH input.
35LM3556 torch can be controlled through sys/class/leds/torch/brightness file.
36* if TORCH pin is enabled, below example control brightness only,
37and ON / OFF will be controlled by TORCH pin.
38
39Torch Example:
40OFF : #echo 0 > sys/class/leds/torch/brightness
4146.88 mA: #echo 1 > sys/class/leds/torch/brightness
42... .....
43375 mA : #echo 8 > sys/class/leds/torch/brightness
44
45INDICATOR MODE
46Indicator pattern can be set through sys/class/leds/indicator/pattern file,
47and 4 patterns are pre-defined in indicator_pattern array.
48According to N-lank, Pulse time and N Period values, different pattern wiill
49be generated.If you want new patterns for your own device, change
50indicator_pattern array with your own values and INDIC_PATTERN_SIZE.
51Please refer datasheet for more detail about N-Blank, Pulse time and N Period.
52
53Indicator pattern example:
54pattern 0: #echo 0 > sys/class/leds/indicator/pattern
55....
56pattern 3: #echo 3 > sys/class/leds/indicator/pattern
57
58Indicator brightness can be controlled through
59sys/class/leds/indicator/brightness file.
60
61Example:
62OFF : #echo 0 > sys/class/leds/indicator/brightness
635.86 mA : #echo 1 > sys/class/leds/indicator/brightness
64........
6546.875mA : #echo 8 > sys/class/leds/indicator/brightness
66
67Notes
68-----
69Driver expects it is registered using the i2c_board_info mechanism.
70To register the chip at address 0x63 on specific adapter, set the platform data
71according to include/linux/platform_data/leds-lm3556.h, set the i2c board info
72
73Example:
74 static struct i2c_board_info __initdata board_i2c_ch4[] = {
75 {
76 I2C_BOARD_INFO(LM3556_NAME, 0x63),
77 .platform_data = &lm3556_pdata,
78 },
79 };
80
81and register it in the platform init function
82
83Example:
84 board_register_i2c_bus(4, 400,
85 board_i2c_ch4, ARRAY_SIZE(board_i2c_ch4));