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Documentation / backlight / lp855x-driver.txt




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Based on kernel version 3.13. Page generated on 2014-01-20 22:00 EST.

1	Kernel driver lp855x
2	====================
3	
4	Backlight driver for LP855x ICs
5	
6	Supported chips:
7		Texas Instruments LP8550, LP8551, LP8552, LP8553, LP8555, LP8556 and
8		LP8557
9	
10	Author: Milo(Woogyom) Kim <milo.kim@ti.com>
11	
12	Description
13	-----------
14	
15	* Brightness control
16	
17	Brightness can be controlled by the pwm input or the i2c command.
18	The lp855x driver supports both cases.
19	
20	* Device attributes
21	
22	1) bl_ctl_mode
23	Backlight control mode.
24	Value : pwm based or register based
25	
26	2) chip_id
27	The lp855x chip id.
28	Value : lp8550/lp8551/lp8552/lp8553/lp8555/lp8556/lp8557
29	
30	Platform data for lp855x
31	------------------------
32	
33	For supporting platform specific data, the lp855x platform data can be used.
34	
35	* name : Backlight driver name. If it is not defined, default name is set.
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	* size_program : Total size of lp855x_rom_data.
41	* rom_data : List of new eeprom/eprom registers.
42	
43	example 1) lp8552 platform data : i2c register mode with new eeprom data
44	
45	#define EEPROM_A5_ADDR	0xA5
46	#define EEPROM_A5_VAL	0x4f	/* EN_VSYNC=0 */
47	
48	static struct lp855x_rom_data lp8552_eeprom_arr[] = {
49		{EEPROM_A5_ADDR, EEPROM_A5_VAL},
50	};
51	
52	static struct lp855x_platform_data lp8552_pdata = {
53		.name = "lcd-bl",
54		.device_control = I2C_CONFIG(LP8552),
55		.initial_brightness = INITIAL_BRT,
56		.size_program = ARRAY_SIZE(lp8552_eeprom_arr),
57		.rom_data = lp8552_eeprom_arr,
58	};
59	
60	example 2) lp8556 platform data : pwm input mode with default rom data
61	
62	static struct lp855x_platform_data lp8556_pdata = {
63		.device_control = PWM_CONFIG(LP8556),
64		.initial_brightness = INITIAL_BRT,
65		.period_ns = 1000000,
66	};
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