Porting to linux-pmac: how to check that iobase is correct?

[Justin T. Gibbs]

In article <v03130300b10c396bb257@[192.168.1.2]> you wrote:
> I'm working on getting the aic7xxx driver to work in linux-pmac on the
> Macintosh G3.  The driver has already been ported to some other Mac clone
> systems, starting from the driver in Linux 2.1.24, so hopefully once I get
> past my current snag, I won't have too far to go.  That snag is: the value
> I get for iobase (p->base) by reading from PCI_BASE_ADDRESS_0, is 1.  This
> value is obviously completely bogus (presumably the result of the
> Mac-specific firmware on the card--yes?).  Looking at various other
> possible addresses gleaned from Mac-specific machinery associated with the
> card, I have four possible addresses for iobase and mbase, but so far I
> have not been able to get anything reasonable to happen using any of the
> four addresses as iobase.

It seems that the card is only memory mapped.  I'm sure that if you look
at the PCI address access enable bits, you'll see that only memory access
is allowed.  The Linux driver should ignore iobase in this case and
simply perform memory mapped I/O.

You may also run into issues with byte order in the driver unless
Linux always runs the PowerPC in LE mode.

--
Justin

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