[PATCH 2.6.8.1 0/2] leds: new class for led devices

[John Lenz <lenz@cs.wisc.edu>]

This is an attempt to provide an alternative to the current arm  
specific led interface.  This arm interface does not integrate well  
with the device model and sysfs.

We create a new class that drivers can register a leds_properties  
structure with.  Each led that is registered is assigned a number, and  
three attributes are exported to sysfs in /sys/class/leds/1/, /sys/ 
class/leds/2, etc.

color : a read only string attribute that shows the available colors of  
this led.  If it is a multi-color led, then the colors are seperated by  
a "/" (for example "green/blue").

function : a read/write attribute that sets the current function of  
this led.  The available options are

  timer : the led blinks on and off on a timer
  idle : the led turns off when the system is idle and on when not idle
  power : the led represents the current power state
  user : the led is controlled by user space

light : a read/write attribute that allows userspace to see the current  
status of the led.  If function="user" then writing to this attribute  
will change the led on or off.  If function != "user" then writing has  
no effect.
  light is an integer, where 0 means off, 1 means on first color, 2  
means on second color, etc.  (for example, if color="green/blue" then  
light=1 means turn led on to green and if light=2 means turn led on to  
blue.

A device and driver symlink point to the actual driver and such, so any  
extra attributes can also be registered.

Signed-off-by: John Lenz <lenz@cs.wisc.edu>