Documentation/backlight/lp855x-driver.txt

   1 Kernel driver lp855x
   2 ====================
   3
   4 Backlight driver for LP855x ICs
   5
   6 Supported chips:
   7         Texas Instruments LP8550, LP8551, LP8552, LP8553 and LP8556
   8
   9 Author: Milo(Woogyom) Kim <milo.kim@ti.com>
  10
  11 Description
  12 -----------
  13
  14 * Brightness control
  15
  16 Brightness can be controlled by the pwm input or the i2c command.
  17 The lp855x driver supports both cases.
  18
  19 * Device attributes
  20
  21 1) bl_ctl_mode
  22 Backlight control mode.
  23 Value : pwm based or register based
  24
  25 2) chip_id
  26 The lp855x chip id.
  27 Value : lp8550/lp8551/lp8552/lp8553/lp8556
  28
  29 Platform data for lp855x
  30 ------------------------
  31
  32 For supporting platform specific data, the lp855x platform data can be used.
  33
  34 * name : Backlight driver name. If it is not defined, default name is set.
  35 * mode : Brightness control mode. PWM or register based.
  36 * device_control : Value of DEVICE CONTROL register.
  37 * initial_brightness : Initial value of backlight brightness.
  38 * pwm_data : Platform specific pwm generation functions.
  39              Only valid when brightness is pwm input mode.
  40              Functions should be implemented by PWM driver.
  41              - pwm_set_intensity() : set duty of PWM
  42              - pwm_get_intensity() : get current duty of PWM
  43 * load_new_rom_data :
  44         0 : use default configuration data
  45         1 : update values of eeprom or eprom registers on loading driver
  46 * size_program : Total size of lp855x_rom_data.
  47 * rom_data : List of new eeprom/eprom registers.
  48
  49 example 1) lp8552 platform data : i2c register mode with new eeprom data
  50
  51 #define EEPROM_A5_ADDR  0xA5
  52 #define EEPROM_A5_VAL   0x4f    /* EN_VSYNC=0 */
  53
  54 static struct lp855x_rom_data lp8552_eeprom_arr[] = {
  55         {EEPROM_A5_ADDR, EEPROM_A5_VAL},
  56 };
  57
  58 static struct lp855x_platform_data lp8552_pdata = {
  59         .name = "lcd-bl",
  60         .mode = REGISTER_BASED,
  61         .device_control = I2C_CONFIG(LP8552),
  62         .initial_brightness = INITIAL_BRT,
  63         .load_new_rom_data = 1,
  64         .size_program = ARRAY_SIZE(lp8552_eeprom_arr),
  65         .rom_data = lp8552_eeprom_arr,
  66 };
  67
  68 example 2) lp8556 platform data : pwm input mode with default rom data
  69
  70 static struct lp855x_platform_data lp8556_pdata = {
  71         .mode = PWM_BASED,
  72         .device_control = PWM_CONFIG(LP8556),
  73         .initial_brightness = INITIAL_BRT,
  74         .pwm_data = {
  75                      .pwm_set_intensity = platform_pwm_set_intensity,
  76                      .pwm_get_intensity = platform_pwm_get_intensity,
  77                      },
  78 };