How to port PReP to arch/powerpc?

It seems no one cares for arch/ppc any more but the move to powerpc was 
not finished completely (PReP subarch was not migrated but sees users, I 
do not know about the user base of the other subarches). So I have been 
thinking about migrating PReP support to arch/powerpc myself since I use 
it.

Any general guidelines or specific hints about that? I have looked 
around in the code and some pieces are clearly PReP specific (setup, 
pci, boot) but others seem wuite a bit mixed up with other subarches.

-- 
Meelis Roos (mroos@linux.ee)