Re: [PATCH v2 05/16] dt-bindings: dma: add Canaan k210 to Synopsys DesignWare DMA

[Serge Semin]

On Mon, Jun 27, 2022 at 08:39:53PM +0100, Conor Dooley wrote:
> From: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
> 
> The Canaan k210 apparently has a Sysnopsys Designware AXI DMA
> controller, but according to the documentation & devicetree it has 6
> interrupts rather than the standard one. Add a custom compatible that
> supports the 6 interrupt configuration which falls back to the standard
> binding which is currently the one in use in the devicetree entry.
> 
> Link: https://canaan-creative.com/wp-content/uploads/2020/03/kendryte_standalone_programming_guide_20190311144158_en.pdf #Page 58

I believe what you've got here is the per-channel IRQs, which is
activated for the DW AXI DMAC by setting IP-core synthesize parameter
DMAX_INTR_IO_TYPE=1 (CHANNEL AND COMMONREG). That's why there are six
IRQ signals and six DMA-channels available.

Seeing such setting isn't the Canaan k210 specific, but is the DW AXI
DMA controller common property, what would be right in this case is to
unconditionally extend the number of IRQs in the DT-bindings schema.

Please note the DW AXI DMAC driver currently doesn't support the
per-channel IRQs. So most likely the DMA will only work with using the
channel 0 only.

-Sergey

> Signed-off-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
> ---
>  .../bindings/dma/snps,dw-axi-dmac.yaml        | 35 ++++++++++++++-----
>  1 file changed, 26 insertions(+), 9 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/dma/snps,dw-axi-dmac.yaml b/Documentation/devicetree/bindings/dma/snps,dw-axi-dmac.yaml
> index 4324a94b26b2..bc85598151ef 100644
> --- a/Documentation/devicetree/bindings/dma/snps,dw-axi-dmac.yaml
> +++ b/Documentation/devicetree/bindings/dma/snps,dw-axi-dmac.yaml
> @@ -18,9 +18,13 @@ allOf:
>  
>  properties:
>    compatible:
> -    enum:
> -      - snps,axi-dma-1.01a
> -      - intel,kmb-axi-dma
> +    oneOf:
> +      - items:
> +          - const: canaan,k210-axi-dma
> +          - const: snps,axi-dma-1.01a
> +      - enum:
> +          - snps,axi-dma-1.01a
> +          - intel,kmb-axi-dma
>  
>    reg:
>      minItems: 1
> @@ -33,9 +37,6 @@ properties:
>        - const: axidma_ctrl_regs
>        - const: axidma_apb_regs
>  
> -  interrupts:
> -    maxItems: 1
> -
>    clocks:
>      items:
>        - description: Bus Clock
> @@ -92,6 +93,22 @@ properties:
>      minimum: 1
>      maximum: 256
>  
> +if:
> +  properties:
> +    compatible:
> +      contains:
> +        const: canaan,k210-axi-dma
> +
> +then:
> +  properties:
> +    interrupts:
> +      maxItems: 6
> +
> +else:
> +  properties:
> +    interrupts:
> +      maxItems: 1
> +
>  required:
>    - compatible
>    - reg
> @@ -105,7 +122,7 @@ required:
>    - snps,priority
>    - snps,block-size
>  
> -additionalProperties: false
> +unevaluatedProperties: false
>  
>  examples:
>    - |
> @@ -113,12 +130,12 @@ examples:
>       #include <dt-bindings/interrupt-controller/irq.h>
>       /* example with snps,dw-axi-dmac */
>       dmac: dma-controller@80000 {
> -         compatible = "snps,axi-dma-1.01a";
> +         compatible = "canaan,k210-axi-dma", "snps,axi-dma-1.01a";
>           reg = <0x80000 0x400>;
>           clocks = <&core_clk>, <&cfgr_clk>;
>           clock-names = "core-clk", "cfgr-clk";
>           interrupt-parent = <&intc>;
> -         interrupts = <27>;
> +         interrupts = <27>, <28>, <29>, <30>, <31>, <32>;
>           #dma-cells = <1>;
>           dma-channels = <4>;
>           snps,dma-masters = <2>;
> -- 
> 2.36.1
>