Re: [PATCH 3/3] dt-binding: iio: Add documentation for ADF4371 channel child notes

[Jonathan Cameron <jic23@kernel.org>]

On Thu, 19 Dec 2019 15:37:55 +0200
Beniamin Bia <beniamin.bia@analog.com> wrote:

> This patch documents the ADF4371 individual channel configuration.
> 
> Signed-off-by: Beniamin Bia <beniamin.bia@analog.com>
> ---
>  .../bindings/iio/frequency/adf4371.yaml       | 63 +++++++++++++++++++
>  1 file changed, 63 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/iio/frequency/adf4371.yaml b/Documentation/devicetree/bindings/iio/frequency/adf4371.yaml
> index 7ec3ec94356b..5339c929e883 100644
> --- a/Documentation/devicetree/bindings/iio/frequency/adf4371.yaml
> +++ b/Documentation/devicetree/bindings/iio/frequency/adf4371.yaml
> @@ -40,12 +40,48 @@ properties:
>        output stage will shut down until the ADF4371/ADF4372 achieves lock as
>        measured by the digital lock detect circuitry.
>  
> +  '#address-cells':
> +    const: 1
> +
> +  '#size-cells':
> +    const: 0
> +
>  required:
>    - compatible
>    - reg
>    - clocks
>    - clock-names
>  
> +  patternProperties:
> +  "^channel@[01]$":
> +    type: object
> +    description: Represents the external channels which are connected to the device.
> +
> +    properties:
> +      reg:
> +        description: |
> +          The channel number. It can have up to 3 channels on adf4372
> +          and 4 channels on adf4371, numbered from 0 to 3.
> +        maxItems: 1
> +
> +      adi,output-enable:
> +        description: |
> +          If this property is specified, the output channel will be enabled.
> +          If left empty, the driver will initialize the defaults (RF8x, channel 0
> +          will be the only one enabled).

If I read the driver right, this is effectively 'power up channel when driver
loads'.  Why do we need that in DT?  A bit of udev magic or similar and the existing
controls can set both this and the frequency below.  Would happen a tiny
bit after the driver loads, but I assume the driver current loads with the channels
turned off so that shouldn't matter...

> +        maxItems: 1
> +
> +      adi,power-up-frequency:
> +        description: |
> +          Set the frequency after power up for the channel. If this property is
> +          specified, it has to be in sync with the power up frequency set on the
> +          other channels. This limitation is due to the fact that all the channel
> +          frequencies are derived from the VCO fundamental frequency.
> +        maxItems: 1
> +
> +    required:
> +      - reg
> +
>  examples:
>    - |
>      spi0 {
> @@ -55,9 +91,36 @@ examples:
>          frequency@0 {
>                  compatible = "adi,adf4371";
>                  reg = <0>;
> +
> +                #address-cells = <1>;
> +                #size-cells = <0>;
> +
>                  spi-max-frequency = <1000000>;
>                  clocks = <&adf4371_clkin>;
>                  clock-names = "clkin";
> +
> +                channel@0 {
> +                        reg = <0>;
> +                        adi,output-enable;
> +                        adi,power-up-frequency = /bits/ 64 <8000000000>;
> +                };
> +
> +                channel@1 {
> +                        reg = <1>;
> +                        adi,output-enable;
> +                };
> +
> +                channel@2 {
> +                        reg = <2>;
> +                        adi,output-enable;
> +                        adi,power-up-frequency = /bits/ 64 <16000000000>;
> +                };
> +
> +                channel@3 {
> +                        reg = <3>;
> +                        adi,output-enable;
> +                        adi,power-up-frequency = /bits/ 64 <32000000000>;
> +                };
>          };
>      };
>  ...