In article <rmi7jow5ubl.fsf@fnord.ir.bbn.com> you write:
> The cleanest way: make the actual lower-level drivers have softcs, and
> make the upper layer into a pseudo-driver kind of like scsibus, usb,
> audio, atabus, pcmcia, etc.

Indeed, it seems to me like it would be especially nice if the upper
layer *was* the "audio" driver, or an extended variant thereof.

Wether this would play nicely with Asterisk, I don't know, but it seems
like the right thing genrally to me.