Working:
- Playback/Capture (up to 3 playbackstreams)/Pause
- Mixer (AC97)
- OPL3/MPU/Joysick (? not testet)

Not working:
- I2S play/capture

TODO:
- get docs about i2s paths/channels etc.
- add more/other playbackpaths
- test opl3/modem/mpu
- verify firmware version readout for different chips
- make command interface irq driven
- investigate: sometimes hangs in heavy load condition (and continues after some repeated blocks)
