==================== Kernel driver lp855x

Backlight driver for LP855x ICs

Supported chips:

Texas Instruments LP8550, LP8551, LP8552, LP8553, LP8555, LP8556 and
LP8557

Author: Milo(Woogyom) Kim [email protected]

Description

• Brightness control

  Brightness can be controlled by the pwm input or the i2c command. The lp855x driver supports both cases.

• Device attributes

  1. bl_ctl_mode

  Backlight control mode.

  Value: pwm based or register based

  2. chip_id

  The lp855x chip id.

  Value: lp8550/lp8551/lp8552/lp8553/lp8555/lp8556/lp8557

Platform data for lp855x

For supporting platform specific data, the lp855x platform data can be used.

• name: Backlight driver name. If it is not defined, default name is set.
• device_control: Value of DEVICE CONTROL register.
• initial_brightness: Initial value of backlight brightness.
• period_ns: Platform specific PWM period value. unit is nano. Only valid when brightness is pwm input mode.
• size_program: Total size of lp855x_rom_data.
• rom_data: List of new eeprom/eprom registers.

Examples

1. lp8552 platform data: i2c register mode with new eeprom data::

   #define EEPROM_A5_ADDR 0xA5 #define EEPROM_A5_VAL 0x4f /* EN_VSYNC=0 */

   static struct lp855x_rom_data lp8552_eeprom_arr[] = { {EEPROM_A5_ADDR, EEPROM_A5_VAL}, };

   static struct lp855x_platform_data lp8552_pdata = { .name = "lcd-bl", .device_control = I2C_CONFIG(LP8552), .initial_brightness = INITIAL_BRT, .size_program = ARRAY_SIZE(lp8552_eeprom_arr), .rom_data = lp8552_eeprom_arr, };

2. lp8556 platform data: pwm input mode with default rom data::

   static struct lp855x_platform_data lp8556_pdata = { .device_control = PWM_CONFIG(LP8556), .initial_brightness = INITIAL_BRT, .period_ns = 1000000, };