Funtions added:
- setup all the USB audio class device descriptors
- handle class specific setup request
- receive data from USB host by ISO transfer
- play audio data by ALSA sound card
- open and setup playback PCM interface
- set default playback PCM parameters
- provide playback functions for USB audio driver
- provide PCM parameters set/get functions
Test on:
- Host: Ubuntu 8.10, kernel 2.6.27
- Gadget: EZKIT-BF548 with ASoC AD1980 codec
Todo:
- add real Mute control code
- add real Volume control code
- maybe find another way to replace dynamic buffer handling
with static buffer allocation
- test on Windows system
- provide control interface to handle mute/volume control
- provide capture interface in the future
- test on BF527, other USB device controler and other audio codec