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linux/Documentation/backlight/lp855x-driver.txt
Kim, Milo 26e8ccc223 backlight: lp855x_bl: support new LP8557 device
LP8557 is one of LP855x family device, but it has different register map
and initialization process.  To support this device, device specific
configuration is done through the lp855x_device_config structure.

Few register definitions are fixed for better readability.
  BRIGHTNESS_CTRL -> LP855X_BRIGHTNESS_CTRL
  DEVICE_CTRL     -> LP855X_DEVICE_CTRL
  EEPROM_START    -> LP855X_EEPROM_START
  EEPROM_END      -> LP855X_EEPROM_END
  EPROM_START     -> LP8556_EPROM_START
  EPROM_END       -> LP8556_EPROM_END

And LP8557 register definitions are added.  New register function,
lp855x_update_bit() is added.

Signed-off-by: Milo(Woogyom) Kim <milo.kim@ti.com>
Acked-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-02-21 17:22:25 -08:00

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Kernel driver lp855x
====================
Backlight driver for LP855x ICs
Supported chips:
Texas Instruments LP8550, LP8551, LP8552, LP8553, 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/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.
* mode : Brightness control mode. PWM or register based.
* 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.
* load_new_rom_data :
0 : use default configuration data
1 : update values of eeprom or eprom registers on loading driver
* 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",
.mode = REGISTER_BASED,
.device_control = I2C_CONFIG(LP8552),
.initial_brightness = INITIAL_BRT,
.load_new_rom_data = 1,
.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 = {
.mode = PWM_BASED,
.device_control = PWM_CONFIG(LP8556),
.initial_brightness = INITIAL_BRT,
.period_ns = 1000000,
};