Hi Rob,
On Tue, 20 Jun 2023 10:45:21 -0600
Rob Herring <robh@xxxxxxxxxx> wrote:
> On Thu, Jun 15, 2023 at 05:26:20PM +0200, Herve Codina wrote:
> > The additional-devs subnode allows to declared some virtual devices
> > as sound card children.
> > These virtual devices can then be used by the sound card and so be
> > present in the audio path.
> >
> > The first virtual device supported is the audio IIO auxiliary device
> > in order to support an IIO device as an audio auxiliary device.
> >
> > Signed-off-by: Herve Codina <herve.codina@xxxxxxxxxxx>
> > ---
> > .../bindings/sound/simple-card.yaml | 53 +++++++++++++++++++
> > 1 file changed, 53 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/sound/simple-card.yaml b/Documentation/devicetree/bindings/sound/simple-card.yaml
> > index b05e05c81cc4..59ac2d1d1ccf 100644
> > --- a/Documentation/devicetree/bindings/sound/simple-card.yaml
> > +++ b/Documentation/devicetree/bindings/sound/simple-card.yaml
> > @@ -148,6 +148,15 @@ definitions:
> > required:
> > - sound-dai
> >
> > + additional-devs:
> > + type: object
> > + description:
> > + Additional devices used by the simple audio card.
> > + patternProperties:
> > + '^iio-aux(-.+)?$':
> > + type: object
> > + $ref: audio-iio-aux.yaml#
> > +
> > properties:
> > compatible:
> > contains:
> > @@ -187,6 +196,8 @@ properties:
> > $ref: "#/definitions/mclk-fs"
> > simple-audio-card,aux-devs:
> > $ref: "#/definitions/aux-devs"
> > + simple-audio-card,additional-devs:
> > + $ref: "#/definitions/additional-devs"
>
> Why do you need this under the card node? Can't you just use the
> existing aux-devs?
aux-devs is a phandle array referencing auxiliary devices.
I cannot define a node with just aux-devs, just reference.
I need device auxiliary devices that are not defined somewhere else in
the DT.
A SPI amplifier is defined as a subnode of a SPI controler.
But my IIO/ASoC virtual devices are not defined under some hardware bus.
I need to define them here, as a simple-audio-card subnode.
Several subnodes are already defined for a simple-audio-card subnode for
other purpose.
Instead of having virtual device nodes directly as chidren mixed with the
other purpose nodes of the simple-audio-card, I group them under the
additional-devs node in order to ease evolution and maintenance.
Best regards,
Hervé
>
> > simple-audio-card,convert-rate:
> > $ref: "#/definitions/convert-rate"
> > simple-audio-card,convert-channels:
> > @@ -359,6 +370,48 @@ examples:
> > };
> > };
> >
> > +# --------------------
> > +# route audio to/from a codec through an amplifier
> > +# designed with a potentiometer driven by IIO:
> > +# --------------------
> > + - |
> > + sound {
> > + compatible = "simple-audio-card";
> > +
> > + simple-audio-card,aux-devs = <&_in>, <&_out>;
> > + simple-audio-card,routing =
> > + "CODEC LEFTIN", "AMP_IN LEFT OUT",
> > + "CODEC RIGHTIN", "AMP_IN RIGHT OUT",
> > + "AMP_OUT LEFT IN", "CODEC LEFTOUT",
> > + "AMP_OUT RIGHT IN", "CODEC RIGHTOUT";
> > +
> > + simple-audio-card,additional-devs {
> > + amp_out: iio-aux-out {
> > + compatible = "audio-iio-aux";
> > + io-channels = <&pot_out 0>, <&pot_out 1>;
> > + io-channel-names = "LEFT", "RIGHT";
> > + snd-control-invert-range = <1 1>;
> > + sound-name-prefix = "AMP_OUT";
> > + };
> > +
> > + amp_in: iio_aux-in {
> > + compatible = "audio-iio-aux";
> > + io-channels = <&pot_in 0>, <&pot_in 1>;
> > + io-channel-names = "LEFT", "RIGHT";
> > + sound-name-prefix = "AMP_IN";
> > + };
> > + };
> > +
> > + simple-audio-card,cpu {
> > + sound-dai = <&cpu>;
> > + };
> > +
> > + simple-audio-card,codec {
> > + sound-dai = <&codec>;
> > + clocks = <&clocks>;
> > + };
> > + };
> > +
> > # --------------------
> > # Sampling Rate Conversion
> > # --------------------
> > --
> > 2.40.1
> >
--
Hervé Codina, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
