Understanding newPCM driver

[Artem 'Zazoobr' Ignatjev]

Hi
I wish to teach FreeBSD (5.0-CURRENT, somewhere in mid-may, last cvsup
was week ago) make use of that fancy S/P-DIF connector on my Yamaha
soundcard. OTOH, I want to implement it in a Right Way (tm), so that one
can choose, whether he wish to use or not to use this feature, if it's
present. Which is the Right Way(tm) to add such functionality to
existing newPCM driver?

PS: I'm crossposting both -hackers and -current...
-- 
Artem 'Zazoobr' Ignatjev <timon at memphis.mephi.ru>