fbdev: powerpc: driver for Freescale 8610 and 5121 DIU

The following features are supported:
plane 0 works as a regular frame buffer, can be accessed by /dev/fb0
plane 1 has two AOIs (area of interest), can be accessed by /dev/fb1 and /dev/fb2
plane 2 has two AOIs, can be accessed by /dev/fb3 and /dev/fb4
Special ioctls support AOIs

All /dev/fb* can be used as regular frame buffer devices, except hardware
change can only be made through /dev/fb0.  Changing pixel clock has no effect
on other fbs.

Limitation of usage of AOIs:
AOIs on the same plane can not be horizonally overlapped
AOIs have horizonal order, i.e. AOI0 should be always on top of AOI1
AOIs can not beyond phisical display area. Application should check AOI geometry
before changing physical resolution on /dev/fb0

required command line parameters to preallocate memory for frame buffer diufb.

optional command line parameters to set modes and monitor
video=fslfb:[resolution][,bpp][,monitor]
Syntax:

Resolution
xres x yres-bpp@refresh_rate, the -bpp and @refresh_rate are optional
eg, 1024x768, 1280x1024, 1280x1024-32, 1280x1024@60, 1280x1024-32@60, 1280x480-32@60

Bpp
bpp=32, bpp=24, or bpp=16

Monitor
monitor=0, monitor=1, monitor=2
0 is DVI
1 is Single link LVDS
2 is Double link LVDS

Note: switching monitor is a board feather, not DIU feather. MPC8610HPCD has three
monitor ports to swtich to. MPC5121ADS doesn't have additional monitor port. So switching
monirot port for MPC5121ADS has no effect.

If compiled as a module, it takes pamameters mode, bpp, monitor with the same syntax above.

Signed-off-by: York Sun <yorksun@freescale.com>
Signed-off-by: Timur Tabi <timur@freescale.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>