CHROMIUM: ASoC: Tegra: Seaboard: Add machine support

CHROMIUM: ASoC: Tegra: Seaboard: Add machine support

Seaboard has slightly different audio connectivity than Harmony/Ventana, so
create a separate ASoC machine driver to support this board.

Future refactoring is needed to share more code between the multiple machine
drivers.

Signed-off-by: Stephen Warren <swarren@nvidia.com>;

BUG=
TEST=

[Stephen Warren, 2011-02-23 22:39:18]

This review is part of a sequence that update ChromeOS to the latest upstream
Tegra ASoC driver, and add support for Seaboard to that driver.

The reviews need to be merged in the following order:
 
http://codereview.chromium.org/6577007
http://codereview.chromium.org/6579016
http://codereview.chromium.org/6580011
http://codereview.chromium.org/6579017
http://codereview.chromium.org/6574010
http://codereview.chromium.org/6577008
http://codereview.chromium.org/6576013

I tested:
* Audio playback on Harmony (headphone jack)
* Audio capture on Harmony (mic jack)
* Audio playback on Seaboard (headphone portion of headset jack)
* Audio capture on Seaboard (mic portion of headset jack)

Note: The existing ASoC machine driver in ChromeOS hacks a number of WM8903
codec registers directly in order to configure capture. This driver does not do
this. In order to record correctly, you will need to run alsamixer, and adjust a
few controls from their default:

Harmony:
Unmute "Left Input PGA"
Raise Level of "Left Input PGA" e.g. to max
Set "Right Capture Mux" to "Left"

(Ventana would be identical to Harmony, except this patchset doesn't set up the
required platform data for Ventana)

Seaboard:
Unmute "Right Input PGA"
Raise Level of "Right Input PGA" e.g. to max
Set "Left Capture Mux" to "Right"

Other platforms are not currently supported, since I haven't written ASoC
machine drivers that support their audio configuration yet. I'll look at the
schematics for other boards next. It's possible that one of the existing Harmony
or Seaboard machine drivers will be suitable for the other platforms already.

[Olof Johansson, 2011-03-07 00:26:41]

Applied, thanks!