backlight: add LM3533 backlight driver

Add sub-driver for the backlights on National Semiconductor / TI LM3533
lighting power chips.

The chip provides 256 brightness levels and ambient-light-sensor and pwm
input control.

[akpm@linux-foundation.org: fix warning]
[akpm@linux-foundation.org: fix the type of `mode']
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Cc: Rob Landley <rob@landley.net>
Cc: Samuel Ortiz <sameo@linux.intel.com>
Cc: Jonathan Cameron <jic23@cam.ac.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation/ABI/testing/sysfs-class-backlight-driver-lm3533

@@ -0,0 +1,48 @@
+What:		/sys/class/backlight/<backlight>/als_channel
+Date:		May 2012
+KernelVersion:	3.5
+Contact:	Johan Hovold <jhovold@gmail.com>
+Description:
+		Get the ALS output channel used as input in
+		ALS-current-control mode (0, 1), where
+
+		0 - out_current0 (backlight 0)
+		1 - out_current1 (backlight 1)
+
+What:		/sys/class/backlight/<backlight>/als_en
+Date:		May 2012
+KernelVersion:	3.5
+Contact:	Johan Hovold <jhovold@gmail.com>
+Description:
+		Enable ALS-current-control mode (0, 1).
+
+What:		/sys/class/backlight/<backlight>/id
+Date:		April 2012
+KernelVersion:	3.5
+Contact:	Johan Hovold <jhovold@gmail.com>
+Description:
+		Get the id of this backlight (0, 1).
+
+What:		/sys/class/backlight/<backlight>/linear
+Date:		April 2012
+KernelVersion:	3.5
+Contact:	Johan Hovold <jhovold@gmail.com>
+Description:
+		Set the brightness-mapping mode (0, 1), where
+
+		0 - exponential mode
+		1 - linear mode
+
+What:		/sys/class/backlight/<backlight>/pwm
+Date:		April 2012
+KernelVersion:	3.5
+Contact:	Johan Hovold <jhovold@gmail.com>
+Description:
+		Set the PWM-input control mask (5 bits), where
+
+		bit 5 - PWM-input enabled in Zone 4
+		bit 4 - PWM-input enabled in Zone 3
+		bit 3 - PWM-input enabled in Zone 2
+		bit 2 - PWM-input enabled in Zone 1
+		bit 1 - PWM-input enabled in Zone 0
+		bit 0 - PWM-input enabled

drivers/video/backlight/Kconfig

@@ -184,6 +184,18 @@ config BACKLIGHT_GENERIC
 	  known as the Corgi backlight driver. If you have a Sharp Zaurus
 	  SL-C7xx, SL-Cxx00 or SL-6000x say y.
 
+config BACKLIGHT_LM3533
+	tristate "Backlight Driver for LM3533"
+	depends on BACKLIGHT_CLASS_DEVICE
+	depends on MFD_LM3533
+	help
+	  Say Y to enable the backlight driver for National Semiconductor / TI
+	  LM3533 Lighting Power chips.
+
+	  The backlights can be controlled directly, through PWM input, or by
+	  the ambient-light-sensor interface. The chip supports 256 brightness
+	  levels.
+
 config BACKLIGHT_LOCOMO
 	tristate "Sharp LOCOMO LCD/Backlight Driver"
 	depends on SHARP_LOCOMO

drivers/video/backlight/Makefile

@@ -21,6 +21,7 @@ obj-$(CONFIG_BACKLIGHT_EP93XX)	+= ep93xx_bl.o
 obj-$(CONFIG_BACKLIGHT_GENERIC)	+= generic_bl.o
 obj-$(CONFIG_BACKLIGHT_HP700)	+= jornada720_bl.o
 obj-$(CONFIG_BACKLIGHT_HP680)	+= hp680_bl.o
+obj-$(CONFIG_BACKLIGHT_LM3533)	+= lm3533_bl.o
 obj-$(CONFIG_BACKLIGHT_LOCOMO)	+= locomolcd.o
 obj-$(CONFIG_BACKLIGHT_LP855X)	+= lp855x_bl.o
 obj-$(CONFIG_BACKLIGHT_OMAP1)	+= omap1_bl.o