path: root/Documentation/leds/leds-lp3944.txt
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authorAntonio Ospite <ospite@studenti.unina.it>2011-04-04 15:08:46 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-04-04 17:51:47 -0700
commit9a684e19afc630e0763246ee79c0578c1a8eaee8 (patch)
tree46637b603516deb789051f52a09cdf5830b5ac2a /Documentation/leds/leds-lp3944.txt
parent9718269a7f5f6f3d723dd34e05269579a3ccfc1e (diff)
Documentation: consolidate leds files to leds/ subdir
leds: move leds-class documentation under the leds/ subdir. Add also a leds/00-INDEX file describing the files under leds/ Signed-off-by: Antonio Ospite <ospite@studenti.unina.it> Acked-by: Richard Purdie <richard.purdie@linuxfoundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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+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
+ Antonio Ospite <ospite@studenti.unina.it>
+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.
+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));