diff options
author | Tejun Heo <tj@kernel.org> | 2009-07-04 07:13:18 +0900 |
---|---|---|
committer | Tejun Heo <tj@kernel.org> | 2009-07-04 07:13:18 +0900 |
commit | c43768cbb7655ea5ff782ae250f6e2ef4297cf98 (patch) | |
tree | 3982e41dde3eecaa3739a5d1a8ed18d04bd74f01 /Documentation/leds-lp3944.txt | |
parent | percpu: use __weak only in the definition of weak percpu variables (diff) | |
parent | Merge branch 'for-linus' of git://git.infradead.org/users/eparis/notify (diff) | |
download | linux-dev-c43768cbb7655ea5ff782ae250f6e2ef4297cf98.tar.xz linux-dev-c43768cbb7655ea5ff782ae250f6e2ef4297cf98.zip |
Merge branch 'master' into for-next
Pull linus#master to merge PER_CPU_DEF_ATTRIBUTES and alpha build fix
changes. As alpha in percpu tree uses 'weak' attribute instead of
inline assembly, there's no need for __used attribute.
Conflicts:
arch/alpha/include/asm/percpu.h
arch/mn10300/kernel/vmlinux.lds.S
include/linux/percpu-defs.h
Diffstat (limited to 'Documentation/leds-lp3944.txt')
-rw-r--r-- | Documentation/leds-lp3944.txt | 50 |
1 files changed, 50 insertions, 0 deletions
diff --git a/Documentation/leds-lp3944.txt b/Documentation/leds-lp3944.txt new file mode 100644 index 000000000000..c6eda18b15ef --- /dev/null +++ b/Documentation/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)); |