Re: [PATCH 2/9] dt-bindings: iio: dac: adi-axi-adc: Add ad7606 variant

David Lechner
2024-11-21T16:57:48Z

On 11/21/24 4:18 AM, Guillaume Stols wrote:
> A new compatible is added to reflect the specialized version of the HDL
> that is not covered by the IIO backend paradigm: We use the parallel

It still is being used as an IIO backend, so I would leave out the
phrase "that is not covered by the IIO backend paradigm".

> interface to write the ADC's registers, and accessing this interface
> requires to use ADI_AXI_REG_CONFIG_RD,ADI_AXI_REG_CONFIG_WR and
> ADI_AXI_REG_CONFIG_CTRL in a custom fashion.
>
> Signed-off-by: Guillaume Stols <gstols@baylibre.com>
> ---
> Documentation/devicetree/bindings/iio/adc/adi,axi-adc.yaml | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/iio/adc/adi,axi-adc.yaml b/Documentation/devicetree/bindings/iio/adc/adi,axi-adc.yaml
> index e1f450b80db2..43bc0440c678 100644
> --- a/Documentation/devicetree/bindings/iio/adc/adi,axi-adc.yaml
> +++ b/Documentation/devicetree/bindings/iio/adc/adi,axi-adc.yaml
> @@ -17,13 +17,20 @@ description: |
> interface for the actual ADC, while this IP core will interface
> to the data-lines of the ADC and handle the streaming of data into
> memory via DMA.
> + In some cases, the AXI ADC interface is used to perform specialized
> + operation to a particular ADC, e.g access the physical bus through
> + some special register to write ADC registers.
> + In this case, a different compatible is used, and the driver behaves

Quick, delete the word "driver" before Krzysztof sees it. :-p

Joking aside, the devicetree only describes how things are wired up,
it doesn't care how the driver uses the information. So we avoid
mentioning anything about drivers in the bindings.

> + slightly differently according to the special needs.
>
> https://wiki.analog.com/resources/fpga/docs/axi_adc_ip
> + http://analogdevicesinc.github.io/hdl/library/axi_ad7606x/index.html
>
> properties:
> compatible:
> enum:
> - adi,axi-adc-10.0.a
> + - adi,axi-ad7606x
>
> reg:
> maxItems: 1
>

Since this new compatible also provides a bus in addition to the io-backend,
I think we need some additional bindings to describe the child nodes for the
ADC devices attached to the bus.

I don't think there are any generic parallel-controller bindings like there
are for SPI controllers, so we can't $ref: /schemas/spi/spi-controller.yaml#
like we did for the similar case of adi,axi-ad3552r recently.

But maybe something like this:

properties:
...

"#address-cells":
const: 1

"#size-cells":
const: 0

patternProperties:
"^adc@[0-9a-f]+$":
type: object
additionalProperties: true

properties:
reg:
maxItems: 1

required:
- compatible
- reg