Re: [PATCH v2 1/9] dt-bindings: iio: dac: ad3552r: add io-backend property

[Angelo Dureghello]

On 08/09/24 2:29 PM, Jonathan Cameron wrote:
> On Thu, 05 Sep 2024 17:17:31 +0200
> Angelo Dureghello <adureghello@xxxxxxxxxxxx> wrote:
>
> > From: Angelo Dureghello <adureghello@xxxxxxxxxxxx>
> >
> > There is a version AXI DAC IP block (for FPGAs) that provides
> > a physical bus for AD3552R and similar chips. This can be used
> > instead of a typical SPI controller to be able to use the chip
> > in ways that typical SPI controllers are not capable of.
> >
> > The binding is modified so that either the device is a SPI
> > peripheral or it uses an io-backend.
> >
> > Signed-off-by: Angelo Dureghello <adureghello@xxxxxxxxxxxx>
> >   
> >   required:
> >     - compatible
> > -  - reg
> > -  - spi-max-frequency
> Sort of feels like both reg and spi-max-frequency
> are valid things to specify.

This specific backend IP generates a fixed non-configurable clock
frequency, so i don't think the spi-max-frequency is needed.


> Maybe we have an excellent IP and dodgy wiring so want
> to clamp the frequency (long term - don't need to support
> in the driver today).
>
> Maybe we have an axi_dac IP that supports multiple
> front end devices?  So maybe just keep reg?

yes, this is what i am wondering now too, i simplified with just one
frontend node, are multimple frontends (and so reg property) needed ?


> >   
> >   additionalProperties: false
> >   
> > @@ -238,4 +254,26 @@ examples:
> >               };
> >           };
> >       };
> > +
> > +  - |
> > +    backend: axi_dac@44a70000 {
> > +        compatible = "adi,axi-dac-ad3552r";
> > +        reg = <0x44a70000 0x1000>;
> > +        dmas = <&dac_tx_dma 0>;
> > +        dma-names = "tx";
> > +        #io-backend-cells = <0>;
> > +        clocks = <&ref_clk>;
> > +        dac {
> > +            compatible = "adi,ad3552r";
> > +            reset-gpios = <&gpio0 92 1>;
> > +            io-backends = <&backend>;
> > +            #address-cells = <1>;
> > +            #size-cells = <0>;
> > +            channel@0 {
> > +                reg = <0>;
> > +                adi,output-range-microvolt = <(-10000000) (10000000)>;
> > +            };
> > +        };
> > +    };
> > +
> >   ...
Regards,
--
 ,,,      Angelo Dureghello
:: :.     BayLibre -runtime team- Developer
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