Re: [PATCH v3 1/2] dt-bindings: dma: Document DMA mux support for Loongson-2K0300

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

On Mon, Oct 26, 2026 at 12:33:05PM +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.
>
> Acked-by: Conor Dooley <conor.dooley@microchip.com>
> Signed-off-by: Binbin Zhou <zhoubinbin@loongson.cn>
> ---

Reviewed-by: Frank Li <Frank.Li@nxp.com>

>  .../dma/loongson,ls2k0300-dmamux.yaml         | 72 +++++++++++++++++++
>  MAINTAINERS                                   |  2 +
>  .../dt-bindings/dma/loongson,ls2k-dmamux.h    | 53 ++++++++++++++
>  3 files changed, 127 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/dma/loongson,ls2k0300-dmamux.yaml
>  create mode 100644 include/dt-bindings/dma/loongson,ls2k-dmamux.h
>
> 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..df607d9ff599
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/dma/loongson,ls2k0300-dmamux.yaml
> @@ -0,0 +1,72 @@
> +# 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. Peripheral request ID: This describes the corresponding bit field
> +         for that peripheral in the configuration register; see (
> +         include/dt-bindings/dma/loongson,ls2k-dmamux.h) for details.
> +      2. Physical DMA channel (0-7): This not only represents the DMA
> +         channel used by the peripheral but is also converted into a value for
> +         the corresponding bit field in the configuration register, indicating
> +         the legitimacy of that peripheral using that channel.
> +         Specifically:
> +         - I2S/SPI/UART/I2C: Require adjacent channels in pairs; valid
> +            values are 0/1, 2/3, 4/5, 6/7;
> +         - SM3/SM4/DES/AES: Single channel; valid values are limited to 0/1;
> +         - CAN/ADC: Single channel; valid values range from 0 to 7.
> +      3. DMA Channel Configuration: A 32-bit mask used to specify
> +         device-specific DMA channel configurations.
> +         - Bit 6: Peripheral Address Increment Mode
> +            0x0: Disabled
> +            0x1: Enabled
> +         - Bit 7: Memory Address Increment Mode
> +            0x0: Disabled
> +            0x1: Enabled
> +         - Bits 12-13: Priority
> +            0x0: Low
> +            0x1: Medium
> +            0x2: High
> +            0x3: Very High
> +
> +  dma-requests:
> +    const: 22
> +
> +required:
> +  - compatible
> +  - reg
> +  - dma-requests
> +
> +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 42f5165019ee..78622b255f88 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -15351,9 +15351,11 @@ 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
> +F:	include/dt-bindings/dma/loongson,ls2k-dmamux.h
>
>  LOONGSON LS2X I2C DRIVER
>  M:	Binbin Zhou <zhoubinbin@loongson.cn>
> diff --git a/include/dt-bindings/dma/loongson,ls2k-dmamux.h b/include/dt-bindings/dma/loongson,ls2k-dmamux.h
> new file mode 100644
> index 000000000000..1e2907ab069d
> --- /dev/null
> +++ b/include/dt-bindings/dma/loongson,ls2k-dmamux.h
> @@ -0,0 +1,53 @@
> +/* SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) */
> +/*
> + * Loongson-2 SoC DMA Mux dt-bindings
> + *
> + * DMA specifier format:
> + *   dmas = <&dma_mux <request> <channel> <flags>>;
> + *
> + * The <channel> cell selects a physical CMC DMA channel (0-7)
> + * For peripherals using channel pairs (UART, I2C, SPI2/3, I2S),
> + * the channel number selects the pair: 0/1 -> pair 0, 2/3 -> pair 1,
> + * 4/5 -> pair 2, 6/7 -> pair 3.
> + *
> + * Copyright (C) 2026 Loongson Technology Corporation Limited
> + */
> +
> +#ifndef _DT_BINDINGS_DMA_LOONGSON_LS2K_DMAMUX_H
> +#define _DT_BINDINGS_DMA_LOONGSON_LS2K_DMAMUX_H
> +
> +/* UART controllers */
> +#define LS2K0300_DMA_UART0		0
> +#define LS2K0300_DMA_UART1		1
> +#define LS2K0300_DMA_UART2		2
> +#define LS2K0300_DMA_UART3		3
> +#define LS2K0300_DMA_UART4		4
> +#define LS2K0300_DMA_UART5		5
> +#define LS2K0300_DMA_UART6		6
> +#define LS2K0300_DMA_UART7		7
> +#define LS2K0300_DMA_UART8		8
> +#define LS2K0300_DMA_UART9		9
> +
> +/* I2C controllers */
> +#define LS2K0300_DMA_I2C0		10
> +#define LS2K0300_DMA_I2C1		11
> +#define LS2K0300_DMA_I2C2		12
> +#define LS2K0300_DMA_I2C3		13
> +
> +/* SPI controllers (IO mode) */
> +#define LS2K0300_DMA_SPI2		14
> +#define LS2K0300_DMA_SPI3		15
> +
> +/* I2S controller */
> +#define LS2K0300_DMA_I2S		16
> +
> +/* ADC controller */
> +#define LS2K0300_DMA_ADC		17
> +
> +/* CAN-FD controllers */
> +#define LS2K0300_DMA_CAN0		18
> +#define LS2K0300_DMA_CAN1		19
> +#define LS2K0300_DMA_CAN2		20
> +#define LS2K0300_DMA_CAN3		21
> +
> +#endif /* _DT_BINDINGS_DMA_LOONGSON_LS2K_DMAMUX_H */
> --
> 2.52.0
>