Re: Re: Re: Re: How to access vendor specific AC97codecregister?

[Liam Girdwood <liam.girdwood@wolfsonmicro.com>]

On Thu, 2006-04-20 at 13:40 -0400, alasinski wrote:
> Liam Girdwood wrote:
> 
> >> > You will only be able to access these functions from an ad-hoc AC97
> >> > driver. Please see the UCB14xx touch driver for implementation details.
> >> - where I can find it ?
> >
> > Please use Google.
> Your Google must be better then mine. But I don't give up, I'm still 
> looking. For sure UCB14xx leads nowhere. Little hint could go long way.
> 

Google for "linux ucb touchscreen driver" 

Also look in drivers/mfd/

> >
> > This wont work for AC97 codec registers as they are not part of the host
> > memory map and are accessed via the hosts AC97 controller.
> It should. What I intended to do is make same calls as pxa2xx_ac97_read. It 
> talks to memory mapped AC97 codec registers to obtain content of UCB1400 
> registers. They appear to be mapped 1 to 1 with gsr_bit toggled as a 
> handshake protocol.
> 

I'm afraid it's not a simple as that (only register 0x54 can work this
way - see pxa manual on AC97 slot 12). You still have to check and clear
the command and status done bits in GSR. You will also have to manage
access with the audio driver as only one read/write can take place at a
time over the AC97 link. I'm not sure how your going to use your mmap
vm_ops to do all this.

> Is sysfs() going to be more helpfull ?
> 

It depends on what your trying to do.

Liam



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