Kernel driver lp855x

Backlight driver for LP855x ICs

Supported chips:

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

Author: Milo(Woogyom) Kim <milo.kim@ti.com>

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

    1. 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,
};