1 ========================
2 Kernel driver for lm3556
3 ========================
4
5 * Texas Instrument:
6 1.5 A Synchronous Boost LED Flash Driver w/ High-Side Current Source
7 * Datasheet: http://www.national.com/ds/LM/LM3556.pdf
8
9 Authors:
10 - Daniel Jeong
11
12 Contact:Daniel Jeong(daniel.jeong-at-ti.com, gshark.jeong-at-gmail.com)
13
14 Description
15 -----------
16 There are 3 functions in LM3556, Flash, Torch and Indicator.
17
18 Flash Mode
19 ^^^^^^^^^^
20
21 In Flash Mode, the LED current source(LED) provides 16 target current levels
22 from 93.75 mA to 1500 mA.The Flash currents are adjusted via the CURRENT
23 CONTROL REGISTER(0x09).Flash mode is activated by the ENABLE REGISTER(0x0A),
24 or by pulling the STROBE pin HIGH.
25
26 LM3556 Flash can be controlled through /sys/class/leds/flash/brightness file
27
28 * if STROBE pin is enabled, below example control brightness only, and
29 ON / OFF will be controlled by STROBE pin.
30
31 Flash Example:
32
33 OFF::
34
35 #echo 0 > /sys/class/leds/flash/brightness
36
37 93.75 mA::
38
39 #echo 1 > /sys/class/leds/flash/brightness
40
41 ...
42
43 1500 mA::
44
45 #echo 16 > /sys/class/leds/flash/brightness
46
47 Torch Mode
48 ^^^^^^^^^^
49
50 In Torch Mode, the current source(LED) is programmed via the CURRENT CONTROL
51 REGISTER(0x09).Torch Mode is activated by the ENABLE REGISTER(0x0A) or by the
52 hardware TORCH input.
53
54 LM3556 torch can be controlled through /sys/class/leds/torch/brightness file.
55 * if TORCH pin is enabled, below example control brightness only,
56 and ON / OFF will be controlled by TORCH pin.
57
58 Torch Example:
59
60 OFF::
61
62 #echo 0 > /sys/class/leds/torch/brightness
63
64 46.88 mA::
65
66 #echo 1 > /sys/class/leds/torch/brightness
67
68 ...
69
70 375 mA::
71
72 #echo 8 > /sys/class/leds/torch/brightness
73
74 Indicator Mode
75 ^^^^^^^^^^^^^^
76
77 Indicator pattern can be set through /sys/class/leds/indicator/pattern file,
78 and 4 patterns are pre-defined in indicator_pattern array.
79
80 According to N-lank, Pulse time and N Period values, different pattern wiill
81 be generated.If you want new patterns for your own device, change
82 indicator_pattern array with your own values and INDIC_PATTERN_SIZE.
83
84 Please refer datasheet for more detail about N-Blank, Pulse time and N Period.
85
86 Indicator pattern example:
87
88 pattern 0::
89
90 #echo 0 > /sys/class/leds/indicator/pattern
91
92 ...
93
94 pattern 3::
95
96 #echo 3 > /sys/class/leds/indicator/pattern
97
98 Indicator brightness can be controlled through
99 sys/class/leds/indicator/brightness file.
100
101 Example:
102
103 OFF::
104
105 #echo 0 > /sys/class/leds/indicator/brightness
106
107 5.86 mA::
108
109 #echo 1 > /sys/class/leds/indicator/brightness
110
111 ...
112
113 46.875mA::
114
115 #echo 8 > /sys/class/leds/indicator/brightness
116
117 Notes
118 -----
119 Driver expects it is registered using the i2c_board_info mechanism.
120 To register the chip at address 0x63 on specific adapter, set the platform data
121 according to include/linux/platform_data/leds-lm3556.h, set the i2c board info
122
123 Example::
124
125 static struct i2c_board_info board_i2c_ch4[] __initdata = {
126 {
127 I2C_BOARD_INFO(LM3556_NAME, 0x63),
128 .platform_data = &lm3556_pdata,
129 },
130 };
131
132 and register it in the platform init function
133
134 Example::
135
136 board_register_i2c_bus(4, 400,
137 board_i2c_ch4, ARRAY_SIZE(board_i2c_ch4));
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