Issue 207: Add/extend driver for Audio

Reported by Nikolaus Schaller, Jan 29, 2011

so that we can control the PCM audio paths:
* speakers
* Audio In
* UMTS audio
* Bluetooth Audio

Comment 1 by Nikolaus Schaller, Jun 3, 2011

The BB already contains the TWL4030 sound/soc driver which is very 
universal.

But we need to configure:
* some nc pins (Carkit, digital microphone etc.)
* headset jack detection
* enable TV-Out (needs to mute HS Mic)
* enable AUX-IN (needs to mute HS out)

Then, we have a problem (compare with issue 236 of the hardware 
project):
the TPS is designed to have two (or three) PCM/I2S interaces - one 
from the CPU (McBSP2) to play audio files, a second one for voice 
(should be connected to the Modem) and a third for a Bluetooth 
headset.

The voice and the bluetooth connections are not available in our 
current hardware design (may be changed in future releases). But we 
have the UMTS modem voice on McBSP4 of the CPU.

So we have to either
* find a trick to add the McBSP4 interface to the TWL driver
* or have the McBSP4 as a separate (logical) sound card (that 
represents speaker&microphone of the remote telephony link)
* add some routing between channels and/or sound cards

Comment 2 by Nikolaus Schaller, Oct 6, 2011

Done. Except switching AUX-In.

Status: Fixed

Letux Kernel