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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¶

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,
};

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,
};