With the attached patch I am able to use the sound on a new IMac 27.
What works:

*) Internal speakers
*) Internal microphone
*) Headphone

I don't have an external mic or a SPDIF device to test the rest.
Signed-off-by: Rafael Avila de Espindola <rafael.espindola@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>