Based on kernel version 4.16.1. Page generated on 2018-04-09 11:53 EST.
1 Kernel 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 8 Authors: 9 Daniel Jeong 10 Contact:Daniel Jeong(daniel.jeong-at-ti.com, gshark.jeong-at-gmail.com) 11 12 Description 13 ----------- 14 There are 3 functions in LM3556, Flash, Torch and Indicator. 15 16 FLASH MODE 17 In Flash Mode, the LED current source(LED) provides 16 target current levels 18 from 93.75 mA to 1500 mA.The Flash currents are adjusted via the CURRENT 19 CONTROL REGISTER(0x09).Flash mode is activated by the ENABLE REGISTER(0x0A), 20 or by pulling the STROBE pin HIGH. 21 LM3556 Flash can be controlled through sys/class/leds/flash/brightness file 22 * if STROBE pin is enabled, below example control brightness only, and 23 ON / OFF will be controlled by STROBE pin. 24 25 Flash Example: 26 OFF : #echo 0 > sys/class/leds/flash/brightness 27 93.75 mA: #echo 1 > sys/class/leds/flash/brightness 28 ... ..... 29 1500 mA: #echo 16 > sys/class/leds/flash/brightness 30 31 TORCH MODE 32 In Torch Mode, the current source(LED) is programmed via the CURRENT CONTROL 33 REGISTER(0x09).Torch Mode is activated by the ENABLE REGISTER(0x0A) or by the 34 hardware TORCH input. 35 LM3556 torch can be controlled through sys/class/leds/torch/brightness file. 36 * if TORCH pin is enabled, below example control brightness only, 37 and ON / OFF will be controlled by TORCH pin. 38 39 Torch Example: 40 OFF : #echo 0 > sys/class/leds/torch/brightness 41 46.88 mA: #echo 1 > sys/class/leds/torch/brightness 42 ... ..... 43 375 mA : #echo 8 > sys/class/leds/torch/brightness 44 45 INDICATOR MODE 46 Indicator pattern can be set through sys/class/leds/indicator/pattern file, 47 and 4 patterns are pre-defined in indicator_pattern array. 48 According to N-lank, Pulse time and N Period values, different pattern wiill 49 be generated.If you want new patterns for your own device, change 50 indicator_pattern array with your own values and INDIC_PATTERN_SIZE. 51 Please refer datasheet for more detail about N-Blank, Pulse time and N Period. 52 53 Indicator pattern example: 54 pattern 0: #echo 0 > sys/class/leds/indicator/pattern 55 .... 56 pattern 3: #echo 3 > sys/class/leds/indicator/pattern 57 58 Indicator brightness can be controlled through 59 sys/class/leds/indicator/brightness file. 60 61 Example: 62 OFF : #echo 0 > sys/class/leds/indicator/brightness 63 5.86 mA : #echo 1 > sys/class/leds/indicator/brightness 64 ........ 65 46.875mA : #echo 8 > sys/class/leds/indicator/brightness 66 67 Notes 68 ----- 69 Driver expects it is registered using the i2c_board_info mechanism. 70 To register the chip at address 0x63 on specific adapter, set the platform data 71 according to include/linux/platform_data/leds-lm3556.h, set the i2c board info 72 73 Example: 74 static struct i2c_board_info board_i2c_ch4[] __initdata = { 75 { 76 I2C_BOARD_INFO(LM3556_NAME, 0x63), 77 .platform_data = &lm3556_pdata, 78 }, 79 }; 80 81 and register it in the platform init function 82 83 Example: 84 board_register_i2c_bus(4, 400, 85 board_i2c_ch4, ARRAY_SIZE(board_i2c_ch4));