[PATCH v2 1/3] spi: dt-bindings: Add num-cs property for mpfs-spi

[Conor Dooley]

On Tue, May 14, 2024 at 11:45:06AM +0100, Prajna Rajendra Kumar wrote:
> The PolarFire SoC SPI "hard" controller supports eight CS lines, out of
> which only one CS line is physically wired. The default value of
> 'num-cs' was never set and it did not didn't impose a maximum value.
> 
> To reflect this hardware limitation in the device tree, the binding
> enforces that the 'num-cs' property cannot exceed 1 unless additional
> CS lines are explicitly defined using GPIO descriptors.
> 
> Fixes: 2da187304e55 ("spi: add bindings for microchip mpfs spi")
> Signed-off-by: Prajna Rajendra Kumar <prajna.rajendrakumar at microchip.com>
> ---
>  .../bindings/spi/microchip,mpfs-spi.yaml      | 29 +++++++++++++++++--
>  1 file changed, 26 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/spi/microchip,mpfs-spi.yaml b/Documentation/devicetree/bindings/spi/microchip,mpfs-spi.yaml
> index 74a817cc7d94..ffa8d1b48f8b 100644
> --- a/Documentation/devicetree/bindings/spi/microchip,mpfs-spi.yaml
> +++ b/Documentation/devicetree/bindings/spi/microchip,mpfs-spi.yaml
> @@ -13,9 +13,6 @@ description:
>  maintainers:
>    - Conor Dooley <conor.dooley at microchip.com>

I provided the conditions below, so it's maybe a little disingenuous for
me to provide a review from a dt-bindings correctness point of view, but
then again I am the one listed as a maintainer for this particular
binding and what's being done here does match the hardware, so:

Reviewed-by: Conor Dooley <conor.dooley at microchip.com>

Cheers,
Conor.


>  
> -allOf:
> -  - $ref: spi-controller.yaml#
> -
>  properties:
>    compatible:
>      oneOf:
> @@ -43,6 +40,32 @@ required:
>    - interrupts
>    - clocks
>  
> +allOf:
> +  - $ref: spi-controller.yaml#
> +
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            const: microchip,mpfs-spi
> +    then:
> +      properties:
> +        num-cs:
> +          default: 1
> +
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            const: microchip,mpfs-spi
> +      not:
> +        required:
> +          - cs-gpios
> +    then:
> +      properties:
> +        num-cs:
> +          maximum: 1
> +
>  unevaluatedProperties: false
>  
>  examples:
> -- 
> 2.25.1
> 
> 
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