[linux.git] / Documentation / leds / leds-lp3944.rst

====================
Kernel driver lp3944
====================

  * National Semiconductor LP3944 Fun-light Chip

    Prefix: 'lp3944'

    Addresses scanned: None (see the Notes section below)

    Datasheet:

	Publicly available at the National Semiconductor website
	http://www.national.com/pf/LP/LP3944.html

Authors:
	Antonio Ospite <[email protected]>


Description
-----------
The LP3944 is a helper chip that can drive up to 8 leds, with two programmable
DIM modes; it could even be used as a gpio expander but this driver assumes it
is used as a led controller.

The DIM modes are used to set _blink_ patterns for leds, the pattern is
specified supplying two parameters:

  - period:
	from 0s to 1.6s
  - duty cycle:
	percentage of the period the led is on, from 0 to 100

Setting a led in DIM0 or DIM1 mode makes it blink according to the pattern.
See the datasheet for details.

LP3944 can be found on Motorola A910 smartphone, where it drives the rgb
leds, the camera flash light and the lcds power.


Notes
-----
The chip is used mainly in embedded contexts, so this driver expects it is
registered using the i2c_board_info mechanism.

To register the chip at address 0x60 on adapter 0, set the platform data
according to include/linux/leds-lp3944.h, set the i2c board info::

	static struct i2c_board_info a910_i2c_board_info[] __initdata = {
		{
			I2C_BOARD_INFO("lp3944", 0x60),
			.platform_data = &a910_lp3944_leds,
		},
	};

and register it in the platform init function::

	i2c_register_board_info(0, a910_i2c_board_info,
			ARRAY_SIZE(a910_i2c_board_info));
Commit	Line	Data
8dab9197	1	====================
5054d39e AO	2	Kernel driver lp3944
	3	====================
	4
	5	* National Semiconductor LP3944 Fun-light Chip
8dab9197	6
5054d39e	7	Prefix: 'lp3944'
8dab9197	8
5054d39e	9	Addresses scanned: None (see the Notes section below)
8dab9197 MCC	10
	11	Datasheet:
	12
	13	Publicly available at the National Semiconductor website
	14	http://www.national.com/pf/LP/LP3944.html
5054d39e AO	15
5054d39e AO	16	Authors:
8dab9197	17	Antonio Ospite <[email protected]>
5054d39e AO	18
	19
	20	Description
	21	-----------
	22	The LP3944 is a helper chip that can drive up to 8 leds, with two programmable
	23	DIM modes; it could even be used as a gpio expander but this driver assumes it
	24	is used as a led controller.
	25
	26	The DIM modes are used to set _blink_ patterns for leds, the pattern is
	27	specified supplying two parameters:
8dab9197 MCC	28
	29	- period:
	30	from 0s to 1.6s
	31	- duty cycle:
	32	percentage of the period the led is on, from 0 to 100
5054d39e AO	33
	34	Setting a led in DIM0 or DIM1 mode makes it blink according to the pattern.
	35	See the datasheet for details.
	36
	37	LP3944 can be found on Motorola A910 smartphone, where it drives the rgb
	38	leds, the camera flash light and the lcds power.
	39
	40
	41	Notes
	42	-----
	43	The chip is used mainly in embedded contexts, so this driver expects it is
	44	registered using the i2c_board_info mechanism.
	45
	46	To register the chip at address 0x60 on adapter 0, set the platform data
8dab9197	47	according to include/linux/leds-lp3944.h, set the i2c board info::
5054d39e	48
eb967b6a	49	static struct i2c_board_info a910_i2c_board_info[] __initdata = {
5054d39e AO	50	{
	51	I2C_BOARD_INFO("lp3944", 0x60),
	52	.platform_data = &a910_lp3944_leds,
	53	},
	54	};
	55
8dab9197	56	and register it in the platform init function::
5054d39e AO	57
	58	i2c_register_board_info(0, a910_i2c_board_info,
	59	ARRAY_SIZE(a910_i2c_board_info));