Hi,
I'll give some information about this.
We are using Linux BSP and we could test the audio I/O's by compiling ALSA utils from MPC5121 BSP in order to have acces to alsamixer, arecord, aplay... commands.
Once you do that you can modify the alsamixer controls and activate the microphone and headphones and to record/play simply do something like this:
# arecord -d 10 -f S24_LE -r 48000 -t wav soundfile-48k.wav && aplay -f S24_LE -r 48000 -t wav soundfile-48k.wav
Hope this can help.