SPDIF support in NetBSD

Hi,

I want to write an audio device driver for my audio device, which has an
SPDIF input / output interface.
I looked into NetBSD's audio subsystem, but didn't find any reference to
spdif, or any special handling for that interface, and I wonder how it
should be handled?
- Who shall provide the channel-status information for the HW, is it the
audio subsystem or is it the device driver?
- How should I forward the user-data received from the SPDIF interface to
the application (and the other way around), from the application to the
SPDIF interface?

Thanks,