lp855x-driver.txt
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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
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,
};