Create a SB600 SPI detection heuristic

I know that the data sheets say we can't read the ROM straps, but
creative interpretation of the data sheets yielded a heuristic which
should work pretty well.

NOTE: If you test this, make sure you power down and _unplug_ the
machine for a few minutes before you boot and run flashrom with this
patch.
If the machine is not unplugged for some time, the test will yield
incorrect results.
If you run a slightly older flashrom version than svn HEAD, the test
will yield incorrect results.
If you run any flashrom version (except svn HEAD plus this patch) after
poweron, the test will yield incorrect results.

Explanation:
Older flashrom versions unconditionally write to registers which are
used for this heuristic. These registers are in the S5 power domain, so
even powering down does not clear them, you really have to unplug the
machine and remove the battery if this is a laptop.

Corresponding to flashrom svn r491.

Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>
Acked-by: Stefan Reinauer <stepan@coresystems.de>
1 file changed