Kernel-4.18.0-80.el8_lp855x-driver

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

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.

example 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,
};

example 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,
};