I was thinking that we could have one single helper shared by most
platforms who allow that legacy ISA crap which checks the device-tree
for known ISA devices. That would cover PREP, CHRP and pSeries at
least...

Make the helper check every device node under the ISA
node and translate the "reg" in there.  If the requested
legacy I/O region is a subset of the union of all those,
allow the access, otherwise not.  This should cover all
cases (well at least those with a valid device tree, heh).


Segher