Re: [microblaze-uclinux] Audio device support in XUP2P board for uClinux

[John Williams <jwilliams@xxxxxxxxxxxxxx>]

Hi William,

William Zhang wrote:

> I am working on my master project to implement a SIP Client in the
> uClinux on the XUP2P Virtex II Pro board.  I need audio input and
> output for the SIP client. The board has AC97 codec and Xilinx has the
> IP for AC97 controller. And it has some reference desgin such as the
> BIST utilizing the audio device in the microblaze platform.  In order
> to run it on uClinux, I'll needs to implenment the audio driver for
> linux.  I wonder anybody has some experience in this area and could
> share some advices to start with.  

The AC97 is a very popular audio chipset family, and there are many 
existing Linux drivers for AC97-based sound cards.  However, all of the 
ones I've seen assume a PCI interface to the device, and so are tightly 
hooked into the PCI driver/bus subsystem.

So, you'll still have a bit of work to do, splitting out the 
AC97-specific parts of the driver, from the PCI infrastructure. 
Definitely not impossible, but not trivial either.

I'd dig around various PPC linux/embedded mailing lists, see if such a 
thing was ever done for the PPC/Linux platform.  If so, it will save you 
vast amounts of effort.

> For the kernel selection, is 2.6.x
> kernel a better choice for implementing the driver?

The sound architecture is much cleaner in 2.6, and a quick browse of the 
tree shows some non-PCI AC97 drivers that look like good templates, such as

linux-2.6.x/sound/mips/au1xx0.c

Cheers,

John

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