| 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)); |