See also /sys/class/backlight/<backlight>/ambient_light_level and
/sys/class/backlight/<backlight>/ambient_light_zone.

What:		/sys/class/backlight/<backlight>/<ambient light zone>_max
What:		/sys/class/backlight/<backlight>/l1_daylight_max
What:		/sys/class/backlight/<backlight>/l2_bright_max
What:		/sys/class/backlight/<backlight>/l3_office_max
What:		/sys/class/backlight/<backlight>/l4_indoor_max
What:		/sys/class/backlight/<backlight>/l5_dark_max
Date:		May 2011
KernelVersion:	3.0
Contact:	device-drivers-devel@blackfin.uclinux.org
Description:
		Control the maximum brightness for <ambient light zone>
		on this <backlight>. Values are between 0 and 127. This file
		will also show the brightness level stored for this
		<ambient light zone>.

What:		/sys/class/backlight/<backlight>/<ambient light zone>_dim
What:		/sys/class/backlight/<backlight>/l2_bright_dim
What:		/sys/class/backlight/<backlight>/l3_office_dim
What:		/sys/class/backlight/<backlight>/l4_indoor_dim
What:		/sys/class/backlight/<backlight>/l5_dark_dim
Date:		May 2011
KernelVersion:	3.0
Contact:	device-drivers-devel@blackfin.uclinux.org
Description:
		Control the dim brightness for <ambient light zone>
		on this <backlight>. Values are between 0 and 127, typically
		set to 0. Full off when the backlight is disabled.
		This file will also show the dim brightness level stored for
		this <ambient light zone>.