Clockport devices programming

[Radek Kujawa <radoslaw.kujawa%c0ff33.net@localhost>]

Hi.
        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? I'm interested in experimenting with some of my clockport 
cards. 
        In case of Zorro cards, matching and attaching drivers is quite easy, 
because we have zbus abstraction. This exposes Zorro autoconfig mechanism - 
driver can match the card according to vendor and product ID. However, we have 
no similar mechanism for clockport expansions.
        As I understand, clockport devices are connected directly to 68k bus. 
So matching and attachment must work by "probing" for a card. For example by 
writing some values into bus space where it expects the device, and reading 
values back. Am I right? If that is true, how would example probe procedure 
look? Most NetBSD/Amiga drivers either use zbus, or matchname(). Both of these 
methods seems wrong for clockport. I'm really not sure how should I probe for 
clockport stuff.

Best regards,
Radoslaw Kujawa