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
  
  Authors:
  	Daniel Jeong
  	Contact:Daniel Jeong(daniel.jeong-at-ti.com, gshark.jeong-at-gmail.com)
  
  Description
  -----------
  There are 3 functions in LM3556, Flash, Torch and Indicator.
  
  FLASH MODE
  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
  
  TORCH MODE
  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 MODE
  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.
  
  Example:
  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
  
  Notes
  -----
  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
  
  Example:

  	static struct i2c_board_info board_i2c_ch4[] __initdata = {

  		{
  			 I2C_BOARD_INFO(LM3556_NAME, 0x63),
  			 .platform_data = &lm3556_pdata,
  		 },
  	};
  
  and register it in the platform init function
  
  Example:
  	board_register_i2c_bus(4, 400,
  				board_i2c_ch4, ARRAY_SIZE(board_i2c_ch4));