Re: Clockport devices programming

[Ignatios Souvatzis <is%netbsd.org@localhost>]

On Sun, Oct 03, 2010 at 07:18:40PM +0200, Frank Wille wrote:
> On Tue, 28 Sep 2010 17:07:27 +0200
> Radek Kujawa <radoslaw.kujawa%c0ff33.net@localhost> wrote:
> 
> >     Today I wondered, how one should program devices connected to
> > Amiga 1200 clockport. There are many popular expansion cards available,
> > but I found no drivers for such devices in NetBSD source tree. Is there
> > any example source code I can read?
> 
> AFAIK no clockport devices are supported yet.

Some are - clocks that are at locations where the A2000 clock is -
see dev/a2kbbc.c

As for the probing/matching:

- there are direct and indirect busses.

zbus and pci are direct, that is, the *bus* has knowledge of the
devices that are connected to it, and your driver's *match* function
checks whether the attributes of some device match your driver.

- clockport, ISA, the VAX are indirect, that is, you have a *probe*
function, and it checks whether your hardware is at the addresses you're
configured with. As Frank wrote - this is dangerous - e.g. in the old
days, some ISA probe function for device A used to leave device B in a
state where B's driver wouldn't recognize it, etc. 

I have some clockport devices' documentation somewhere, I think. I'll
see what I can find.

Regards,
        -is