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