Re: [PATCH 2/3] dt-bindings: dma: loongson: Add Loongson-2K0300 DMA mux support

[Frank Li <Frank.li@oss.nxp.com>]

On Tue, Sep 22, 2026 at 05:25:43PM +0800, Binbin Zhou wrote:
> The DMA mux on Loongson-2K0300 is not a standalone hardware block. It is
> implemented as part of the chip configuration registers CHIP_CTRL13/14/15,
> which route peripheral DMA requests to the physical channels of the CMC
> DMA controller.
>
> Document this as a DMA router. The #dma-cells = <3> specifier contains
> the peripheral request ID, the target CMC DMA channel, and channel
> configuration flags forwarded to the parent DMA controller.
>
> Signed-off-by: Binbin Zhou <zhoubinbin@loongson.cn>
> ---
>  .../dma/loongson,ls2k0300-dmamux.yaml         | 49 +++++++++++++++++++
>  MAINTAINERS                                   |  1 +
>  2 files changed, 50 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/dma/loongson,ls2k0300-dmamux.yaml
>
> diff --git a/Documentation/devicetree/bindings/dma/loongson,ls2k0300-dmamux.yaml b/Documentation/devicetree/bindings/dma/loongson,ls2k0300-dmamux.yaml
> new file mode 100644
> index 000000000000..12b8f8af51e9
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/dma/loongson,ls2k0300-dmamux.yaml
> @@ -0,0 +1,49 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/dma/loongson,ls2k0300-dmamux.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Loongson-2 APB DMA MUX (DMA request router)
> +
> +maintainers:
> +  - Binbin Zhou <zhoubinbin@loongson.cn>
> +
> +allOf:
> +  - $ref: /schemas/dma/dma-router.yaml#
> +
> +properties:
> +  compatible:
> +    const: loongson,ls2k0300-dmamux
> +
> +  reg:
> +    maxItems: 1
> +
> +  '#dma-cells':
> +    const: 3
> +    description: |
> +      Each cell represents the following:
> +      1. The peripheral request id (see
> +         include/dt-bindings/dma/loongson,ls2k-dmamux.h)
> +      2. The physical CMC DMA channel (0-7) that is passed to the real
> +         DMA controller

Do you have restriction between request id and channel? Does any request id
route to any channel?

Frank
> +      3. Bitfield representing DMA channel configuration that is passed
> +         to the real DMA controller
> +
> +required:
> +  - compatible
> +  - reg
> +
> +unevaluatedProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/dma/loongson,ls2k-dmamux.h>
> +    dma-router@16000134 {
> +        compatible = "loongson,ls2k0300-dmamux";
> +        reg = <0x16000134 0xc>;
> +        #dma-cells = <3>;
> +        dma-masters = <&dma>;
> +        dma-requests = <22>;
> +    };
> +...
> diff --git a/MAINTAINERS b/MAINTAINERS
> index b021fb623446..dc976938c58c 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -15344,6 +15344,7 @@ M:	Binbin Zhou <zhoubinbin@loongson.cn>
>  L:	dmaengine@vger.kernel.org
>  S:	Maintained
>  F:	Documentation/devicetree/bindings/dma/loongson,ls2k0300-dma.yaml
> +F:	Documentation/devicetree/bindings/dma/loongson,ls2k0300-dmamux.yaml
>  F:	Documentation/devicetree/bindings/dma/loongson,ls2x-apbdma.yaml
>  F:	drivers/dma/loongson/loongson2-apb-cmc-dma.c
>  F:	drivers/dma/loongson/loongson2-apb-dma.c
> --
> 2.52.0
>