[alsa-devel] I2S driver for implants

[Vasily Khoruzhick]

On 23 July 2014 19:43:38 Matt Flax wrote:
> On 23/07/14 18:23, Vasily Khoruzhick wrote:
> > On Wed, Jul 23, 2014 at 11:10 AM, Matt Flax <flatmax at flatmax.org> wrote:
> >> Hi there,
> > 
> > Hi Matt,
> > 
> > I'd suggest you include alsa-devel ML next time (added it to CC)
> > 
> >> I saw your driver sound/soc/samsung
> >> 
> >> I am wanting to look into an I2S driver for the Exynos 5250 for eye
> >> implants.
> > 
> > Driver for I2S in Exynos 5 is already included in mainline kernel.
> > 
> >> The implants use a serial bus and I am wanting to specify an I2S
> >> connection
> >> to them.
> >> 
> >> In order to do that I would need to write an I2S driver to talk to them.
> >> Their bit rates are either 300 kbps or 600 kbps.
> >> They only need I2S and not I2C ... there are not controls, simply serial
> >> data in and out.
> > 
> > Are you sure that your implants can talk over I2S?
> 
> Yes, we do/will have custom hardware to reconstruct the required signals
> from the I2S lines.
> 
> >> I am wondering if I can do something simple ... I notice that your driver
> >> doesn't require too much code ...
> >> Do you think it is possible for me to take a similar approach in writing
> >> my
> >> implant driver ?
> > 
> > Don't know, you didn't share much details on your hardware.
> 
> The hardware requires one I2S output line and one I2S input line + the
> clock line.
> 
> You say "Driver for I2S in Exynos 5 is already included in mainline
> kernel." ... do you mean that all I need is a device tree file to enable
> it ? If so, then can you please link me to an example device tree ... my
> assumption is that this I2S device will show up in alsa once the device
> tree is setup ?

You'd probably need some codec stub, I'm not sure if it's possible to 
instantiate soundcard with only i2s and without a codec.

Regards
Vasily

> >> Can you give me advice - how to start ?
> > 
> > Start with reading specs and try to understand how your implants work,
> > then look at existing code and try to adapt it for your usage.
> > Then clean it up and prepare for submitting into mainline.
> > 
> >> thanks
> >> Matt
> > 
> > Regards,
> > Vasily