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Documentation / backlight / lp855x-driver.txt




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Based on kernel version 3.9. Page generated on 2013-05-02 22:55 EST.

1	Kernel driver lp855x
2	====================
3	
4	Backlight driver for LP855x ICs
5	
6	Supported chips:
7		Texas Instruments LP8550, LP8551, LP8552, LP8553, LP8556 and LP8557
8	
9	Author: Milo(Woogyom) Kim <milo.kim@ti.com>
10	
11	Description
12	-----------
13	
14	* Brightness control
15	
16	Brightness can be controlled by the pwm input or the i2c command.
17	The lp855x driver supports both cases.
18	
19	* Device attributes
20	
21	1) bl_ctl_mode
22	Backlight control mode.
23	Value : pwm based or register based
24	
25	2) chip_id
26	The lp855x chip id.
27	Value : lp8550/lp8551/lp8552/lp8553/lp8556/lp8557
28	
29	Platform data for lp855x
30	------------------------
31	
32	For supporting platform specific data, the lp855x platform data can be used.
33	
34	* name : Backlight driver name. If it is not defined, default name is set.
35	* mode : Brightness control mode. PWM or register based.
36	* device_control : Value of DEVICE CONTROL register.
37	* initial_brightness : Initial value of backlight brightness.
38	* period_ns : Platform specific PWM period value. unit is nano.
39		     Only valid when brightness is pwm input mode.
40	* load_new_rom_data :
41		0 : use default configuration data
42		1 : update values of eeprom or eprom registers on loading driver
43	* size_program : Total size of lp855x_rom_data.
44	* rom_data : List of new eeprom/eprom registers.
45	
46	example 1) lp8552 platform data : i2c register mode with new eeprom data
47	
48	#define EEPROM_A5_ADDR	0xA5
49	#define EEPROM_A5_VAL	0x4f	/* EN_VSYNC=0 */
50	
51	static struct lp855x_rom_data lp8552_eeprom_arr[] = {
52		{EEPROM_A5_ADDR, EEPROM_A5_VAL},
53	};
54	
55	static struct lp855x_platform_data lp8552_pdata = {
56		.name = "lcd-bl",
57		.mode = REGISTER_BASED,
58		.device_control = I2C_CONFIG(LP8552),
59		.initial_brightness = INITIAL_BRT,
60		.load_new_rom_data = 1,
61		.size_program = ARRAY_SIZE(lp8552_eeprom_arr),
62		.rom_data = lp8552_eeprom_arr,
63	};
64	
65	example 2) lp8556 platform data : pwm input mode with default rom data
66	
67	static struct lp855x_platform_data lp8556_pdata = {
68		.mode = PWM_BASED,
69		.device_control = PWM_CONFIG(LP8556),
70		.initial_brightness = INITIAL_BRT,
71		.period_ns = 1000000,
72	};
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