[alsa-devel] GPIO control from ALSA

[Lars-Peter Clausen]

On 04/20/2016 11:47 AM, Petr Kulhavy wrote:
> 
> 
> On 20.04.2016 11:06, Lars-Peter Clausen wrote:
>> On 04/20/2016 10:51 AM, Petr Kulhavy wrote:
>>>
>>> Thanks, Lars, for the good pointers! I will check that out.
>>>
>>> Is there also a way to map GPIO to a control which then appears e.g. in
>>> alsamixer? That would be useful for the mic/line selection.
>> Rather than exposing the GPIO itself you'd expose the logical function of
>> the GPIO. E.g. in your case a ENUM control that allows to switch between
>> microphone and capture and in the background this sets the GPIO according to
>> the selection.
> 
> I understand that, my question was more how to hook the enum to a function
> rather to a codec register?

You can use SOC_ENUM_EXT() to create the control. This macro takes a get and
a put callback where you can manipulate the state of the GPIO. And then just
register the control with the card.