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author | Jiri Kosina <jkosina@suse.cz> | 2011-04-26 10:22:15 +0200 |
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committer | Jiri Kosina <jkosina@suse.cz> | 2011-04-26 10:22:59 +0200 |
commit | 07f9479a40cc778bc1462ada11f95b01360ae4ff (patch) | |
tree | 0676cf38df3844004bb3ebfd99dfa67a4a8998f5 /Documentation/leds/leds-lp3944.txt | |
parent | ath9k_hw: don't touch with treewide double semicolon removal (diff) | |
parent | Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ecr... (diff) | |
download | linux-07f9479a40cc778bc1462ada11f95b01360ae4ff.tar.xz linux-07f9479a40cc778bc1462ada11f95b01360ae4ff.zip |
Merge branch 'master' into for-next
Fast-forwarded to current state of Linus' tree as there are patches to be
applied for files that didn't exist on the old branch.
Diffstat (limited to 'Documentation/leds/leds-lp3944.txt')
-rw-r--r-- | Documentation/leds/leds-lp3944.txt | 50 |
1 files changed, 50 insertions, 0 deletions
diff --git a/Documentation/leds/leds-lp3944.txt b/Documentation/leds/leds-lp3944.txt new file mode 100644 index 000000000000..c6eda18b15ef --- /dev/null +++ b/Documentation/leds/leds-lp3944.txt @@ -0,0 +1,50 @@ +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 <ospite@studenti.unina.it> + + +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 __initdata a910_i2c_board_info[] = { + { + 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)); |