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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 10:05:51 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 10:05:51 +0000 |
commit | 5d1646d90e1f2cceb9f0828f4b28318cd0ec7744 (patch) | |
tree | a94efe259b9009378be6d90eb30d2b019d95c194 /Documentation/leds/leds-lp3944.rst | |
parent | Initial commit. (diff) | |
download | linux-upstream/5.10.209.tar.xz linux-upstream/5.10.209.zip |
Adding upstream version 5.10.209.upstream/5.10.209upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | Documentation/leds/leds-lp3944.rst | 59 |
1 files changed, 59 insertions, 0 deletions
diff --git a/Documentation/leds/leds-lp3944.rst b/Documentation/leds/leds-lp3944.rst new file mode 100644 index 000000000..c2f87dc1a --- /dev/null +++ b/Documentation/leds/leds-lp3944.rst @@ -0,0 +1,59 @@ +==================== +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 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)); |