138 lines
3.0 KiB
ReStructuredText
138 lines
3.0 KiB
ReStructuredText
========================
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Kernel driver for lm3556
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========================
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* Texas Instrument:
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1.5 A Synchronous Boost LED Flash Driver w/ High-Side Current Source
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* Datasheet: http://www.national.com/ds/LM/LM3556.pdf
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Authors:
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- Daniel Jeong
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Contact:Daniel Jeong(daniel.jeong-at-ti.com, gshark.jeong-at-gmail.com)
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Description
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-----------
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There are 3 functions in LM3556, Flash, Torch and Indicator.
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Flash Mode
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^^^^^^^^^^
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In Flash Mode, the LED current source(LED) provides 16 target current levels
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from 93.75 mA to 1500 mA.The Flash currents are adjusted via the CURRENT
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CONTROL REGISTER(0x09).Flash mode is activated by the ENABLE REGISTER(0x0A),
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or by pulling the STROBE pin HIGH.
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LM3556 Flash can be controlled through /sys/class/leds/flash/brightness file
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* if STROBE pin is enabled, below example control brightness only, and
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ON / OFF will be controlled by STROBE pin.
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Flash Example:
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OFF::
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#echo 0 > /sys/class/leds/flash/brightness
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93.75 mA::
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#echo 1 > /sys/class/leds/flash/brightness
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...
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1500 mA::
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#echo 16 > /sys/class/leds/flash/brightness
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Torch Mode
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^^^^^^^^^^
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In Torch Mode, the current source(LED) is programmed via the CURRENT CONTROL
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REGISTER(0x09).Torch Mode is activated by the ENABLE REGISTER(0x0A) or by the
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hardware TORCH input.
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LM3556 torch can be controlled through /sys/class/leds/torch/brightness file.
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* if TORCH pin is enabled, below example control brightness only,
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and ON / OFF will be controlled by TORCH pin.
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Torch Example:
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OFF::
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#echo 0 > /sys/class/leds/torch/brightness
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46.88 mA::
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#echo 1 > /sys/class/leds/torch/brightness
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...
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375 mA::
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#echo 8 > /sys/class/leds/torch/brightness
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Indicator Mode
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^^^^^^^^^^^^^^
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Indicator pattern can be set through /sys/class/leds/indicator/pattern file,
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and 4 patterns are pre-defined in indicator_pattern array.
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According to N-lank, Pulse time and N Period values, different pattern wiill
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be generated.If you want new patterns for your own device, change
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indicator_pattern array with your own values and INDIC_PATTERN_SIZE.
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Please refer datasheet for more detail about N-Blank, Pulse time and N Period.
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Indicator pattern example:
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pattern 0::
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#echo 0 > /sys/class/leds/indicator/pattern
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...
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pattern 3::
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#echo 3 > /sys/class/leds/indicator/pattern
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Indicator brightness can be controlled through
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sys/class/leds/indicator/brightness file.
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Example:
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OFF::
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#echo 0 > /sys/class/leds/indicator/brightness
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5.86 mA::
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#echo 1 > /sys/class/leds/indicator/brightness
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...
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46.875mA::
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#echo 8 > /sys/class/leds/indicator/brightness
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Notes
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-----
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Driver expects it is registered using the i2c_board_info mechanism.
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To register the chip at address 0x63 on specific adapter, set the platform data
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according to include/linux/platform_data/leds-lm3556.h, set the i2c board info
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Example::
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static struct i2c_board_info board_i2c_ch4[] __initdata = {
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{
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I2C_BOARD_INFO(LM3556_NAME, 0x63),
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.platform_data = &lm3556_pdata,
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},
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};
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and register it in the platform init function
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Example::
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board_register_i2c_bus(4, 400,
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board_i2c_ch4, ARRAY_SIZE(board_i2c_ch4));
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