pre-newbus address decoding

[Thomas Moestl]

On Tue, 2003/07/08 at 11:15:26 -0700, Marcel Moolenaar wrote:
> On Tue, Jul 08, 2003 at 03:28:15PM +0200, Thomas Moestl wrote:
> > > 
> > > Q2: Am I correct that the basic logic is to traverse to the root and
> > >     decode the address at each intermediate parent, until we end up
> > >     with what is then the physical address?
> > 
> > Yes. I've put some old sio patches which I use at
> >   http://people.freebsd.org/~tmm/sio-s64-20030612.diff
> > in case you are interested (this is a quick and dirty hack; the
> > code I use to attach the console is at the very end). As you can see,
> > I special-cased the register mapping at PCI and ISA/EBus level (which
> > I guess you want to avoid to be more generic).
> 
> Cool. This is exactly what I'm looking for.
> 
> > > Q4: Given the above, does it make sense to add decoding functionality
> > >     to the bus drivers as a low-level interface between low-level
> > >     console drivers and OFW (ie not using newbus data structures)?
> > 
> > I guess a generic mapping function would be preferable if it is
> > possible and all firmware implementation are close enough to the
> > standard to allow this. The bus drivers will mostly just do the same,
> > but attaching them early would probably be more trouble.
> 
> Ok. I'll add one on the uart branch. At first it'll be a copy of what
> you have in the sio patch, but it'll probably evolve. Unfortunately
> all my UARTs are on EBUS. Then again, a PCI multi I/O card shouldn't
> be that expensive...

EBus is very much like ISA (it was designed to allow easy adaption of
devices designed for ISA); this includes the firmware properties, so
the sparc64 EBus and ISA code share functions to handle them.
 
> Last questions: Since I create a fake bustag, I need to have a valid
> bus space type (bus_space_asi index).
> Am I correct that the PCI types use little endian reads and writes?
> If so, can I avoid the problem by always using 8-byte reads/writes
> and just use type 0 or is the magic slightly more complex and do I
> need to keep track of a proper type while traversing to the root?

At the moment, there is no more magic. It should also be easy to track
the types though; the PCI ones also apply to EBus and ISA.

	- Thomas

-- 
Thomas Moestl <t.moestl at tu-bs.de>	http://www.tu-bs.de/~y0015675/
              <tmm at FreeBSD.org>		http://people.FreeBSD.org/~tmm/
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