The kgdb thread support is woefully out of date (it predates
the pidhash), and needs a complete rewrite before it's useful
again. Just rip it out entirely.

Updating the unified kgdb stub is a more worthwhile endeavour
for anyone that happens to be interested in this, at present
it's just limping along.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

This code has suffered quite a bit of bitrot, do some basic
tidying to get it to a reasonably functional state again.
This gets the basic support and the console working again.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

This rips out most of the needlessly complicated sh_bios and kgdb
trap handling, and forces it all through a common fast dispatch path.
As more debug traps are inserted, it's important to keep them in sync
for all of the parts, not just SH-3/4.

As the SH-2 parts are unable to do traps in the >= 0x40 range, we
restrict the debug traps to the 0x30-0x3f range on all parts, and
also bump the kgdb breakpoint trap down in to this range (from 0xff
to 0x3c) so it's possible to use for nommu.

Optionally, this table can be padded out to catch spurious traps for
SH-3/4, but we don't do that yet..
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

Some kgdb cleanup. Move hexchars/highhex/lowhex to the header, so it can
be reused by sh-sci. Also drop silly ctrl_inl/outl() overloading being
done by the kgdb stub.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!