leds: LED driver for National Semiconductor LP3944 Funlight Chip

LEDs driver for National Semiconductor LP3944 Funlight Chip
http://www.national.com/pf/LP/LP3944.html

This helper chip 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

LP3944 can be found on Motorola A910 smartphone, where it drives the rgb
leds, the camera flash light and the displays backlights.

Signed-off-by: Antonio Ospite <ospite@studenti.unina.it>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>

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));

drivers/leds/Kconfig

@@ -146,6 +146,17 @@ config LEDS_GPIO_OF
 	  of_platform devices.  For instance, LEDs which are listed in a "dts"
 	  file.
 
+config LEDS_LP3944
+	tristate "LED Support for N.S. LP3944 (Fun Light) I2C chip"
+	depends on LEDS_CLASS && I2C
+	help
+    This option enables support for LEDs connected to the National
+    Semiconductor LP3944 Lighting Management Unit (LMU) also known as
+    Fun Light Chip.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called leds-lp3944.
+
 config LEDS_CLEVO_MAIL
 	tristate "Mail LED on Clevo notebook"
 	depends on LEDS_CLASS && X86 && SERIO_I8042 && DMI

drivers/leds/Makefile

@@ -20,6 +20,7 @@ obj-$(CONFIG_LEDS_COBALT_RAQ)		+= leds-cobalt-raq.o
 obj-$(CONFIG_LEDS_SUNFIRE)		+= leds-sunfire.o
 obj-$(CONFIG_LEDS_PCA9532)		+= leds-pca9532.o
 obj-$(CONFIG_LEDS_GPIO)			+= leds-gpio.o
+obj-$(CONFIG_LEDS_LP3944)		+= leds-lp3944.o
 obj-$(CONFIG_LEDS_CLEVO_MAIL)		+= leds-clevo-mail.o
 obj-$(CONFIG_LEDS_HP6XX)		+= leds-hp6xx.o
 obj-$(CONFIG_LEDS_FSG)			+= leds-fsg.o