Re: [PATCH RFC v4 08/15] spi: dt-bindings: axi-spi-engine: add SPI offload properties

[Nuno Sá <noname.nuno@xxxxxxxxx>]

On Wed, 2024-10-23 at 15:59 -0500, David Lechner wrote:
> The AXI SPI Engine has support for hardware offloading capabilities.
> This includes a connection to a DMA controller for streaming RX data
> and a trigger input for starting execution of the SPI message programmed
> in the offload.
> 
> Signed-off-by: David Lechner <dlechner@xxxxxxxxxxxx>
> ---
> v4 changes:
> * Dropped #spi-offload-cells property.
> * Changed subject line.
> 
> v3 changes:
> * Added #spi-offload-cells property.
> * Added properties for triggers and RX data stream connected to DMA.
> 
> v2 changes:
> 
> This is basically a new patch. It partially replaces "dt-bindings: iio:
> offload: add binding for PWM/DMA triggered buffer".
> 
> The controller no longer has an offloads object node and the
> spi-offloads property is now a standard SPI peripheral property.
> ---
>  .../bindings/spi/adi,axi-spi-engine.yaml           | 22 ++++++++++++++++++++++
>  1 file changed, 22 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/spi/adi,axi-spi-engine.yaml
> b/Documentation/devicetree/bindings/spi/adi,axi-spi-engine.yaml
> index d48faa42d025..5281b4871209 100644
> --- a/Documentation/devicetree/bindings/spi/adi,axi-spi-engine.yaml
> +++ b/Documentation/devicetree/bindings/spi/adi,axi-spi-engine.yaml
> @@ -41,6 +41,24 @@ properties:
>        - const: s_axi_aclk
>        - const: spi_clk
>  
> +  trigger-sources:
> +    description:
> +      An array of trigger source phandles for offload instances. The index in
> +      the array corresponds to the offload instance number.
> +    $ref: /schemas/types.yaml#/definitions/phandle-array
> +
> +  dmas:
> +    description:
> +      DMA channels connected to the output stream interface of an offload
> instance.
> +    minItems: 1
> +    maxItems: 32
> +
> +  dma-names:
> +    minItems: 1
> +    maxItems: 32
> +    items:
> +      pattern: "^offload(?:[12]?[0-9]|3[01])-rx$"

I think the core is already capable of tx offload? If so, we could already have that
in the bindings.

- Nuno Sá