Subject: Re: [PATCH v5 1/5] dt-bindings: remoteproc: imx_rproc: Add "rpmsg" subnode support

From: Rob Herring <[email-masked]>
Date: Wed, 12 Nov 2025 06:53:12 -0600

On Tue, Nov 04, 2025 at 02:33:11PM -0600, Shenwei Wang wrote:
> Remote processors may announce multiple devices (e.g., I2C, GPIO) over
> an RPMSG channel. These devices may require corresponding device tree
> nodes, especially when acting as providers, to supply phandles for their
> consumers.
> 
> Define an RPMSG node to work as a container for a group of RPMSG channels
> under the imx_rproc node.
> 
> Each subnode within "rpmsg" represents an individual RPMSG channel. The
> name of each subnode corresponds to the channel name as defined by the
> remote processor.
> 
> All remote devices associated with a given channel are defined as child
> nodes under the corresponding channel node.
> 
> Signed-off-by: Shenwei Wang <[email-masked]>
> ---
>  .../bindings/remoteproc/fsl,imx-rproc.yaml    | 123 ++++++++++++++++++
>  1 file changed, 123 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/remoteproc/fsl,imx-rproc.yaml b/Documentation/devicetree/bindings/remoteproc/fsl,imx-rproc.yaml
> index 57d75acb0b5e..897a16c4f7db 100644
> --- a/Documentation/devicetree/bindings/remoteproc/fsl,imx-rproc.yaml
> +++ b/Documentation/devicetree/bindings/remoteproc/fsl,imx-rproc.yaml
> @@ -84,6 +84,92 @@ properties:
>        This property is to specify the resource id of the remote processor in SoC
>        which supports SCFW
>  
> +  rpmsg:
> +    type: object
> +    additionalProperties: false
> +    description:
> +      Present a group of RPMSG channel devices.
> +
> +    properties:
> +      rpmsg-io-channel:
> +        type: object
> +        additionalProperties: false
> +        properties:
> +          '#address-cells':
> +            const: 1
> +
> +          '#size-cells':
> +            const: 0
> +
> +        patternProperties:
> +          "gpio@[0-9a-f]+$":
> +            type: object
> +            unevaluatedProperties: false
> +            properties:
> +              compatible:
> +                enum:
> +                  - fsl,imx-rpmsg-gpio
> +
> +              reg:
> +                maxItems: 1

I still don't understand what the numbers for 'reg' mean here. You 
explained it and I still don't understand. In any case, it needs to be 
explained in the schema.

For example, why do GPIO and I2C each have their own number space?

> +
> +              "#gpio-cells":
> +                const: 2
> +
> +              gpio-controller: true
> +
> +              interrupt-controller: true
> +
> +              "#interrupt-cells":
> +                const: 2
> +
> +            required:
> +              - compatible
> +              - reg
> +              - "#gpio-cells"
> +              - "#interrupt-cells"
> +
> +            allOf:
> +              - $ref: /schemas/gpio/gpio.yaml#
> +              - $ref: /schemas/interrupt-controller.yaml#
> +
> +        required:
> +          - '#address-cells'
> +          - '#size-cells'
> +
> +      rpmsg-i2c-channel:
> +        type: object
> +        unevaluatedProperties: false
> +        properties:
> +          '#address-cells':
> +            const: 1
> +
> +          '#size-cells':
> +            const: 0
> +
> +        patternProperties:
> +          "i2c@[0-9a-f]+$":
> +            type: object
> +            unevaluatedProperties: false
> +            properties:
> +              compatible:
> +                enum:
> +                  - fsl,imx-rpmsg-i2c
> +
> +              reg:
> +                maxItems: 1
> +
> +            required:
> +              - compatible
> +              - reg
> +
> +            allOf:
> +              - $ref: /schemas/i2c/i2c-controller.yaml#
> +
> +        required:
> +          - '#address-cells'
> +          - '#size-cells'
> +
>  required:
>    - compatible
>  
> @@ -146,5 +232,42 @@ examples:
>                  &mu 3 1>;
>        memory-region = <&vdev0buffer>, <&vdev0vring0>, <&vdev0vring1>, <&rsc_table>;
>        syscon = <&src>;
> +
> +      rpmsg {
> +        rpmsg-io-channel {
> +          #address-cells = <1>;
> +          #size-cells = <0>;
> +
> +          gpio@0 {
> +            compatible = "fsl,imx-rpmsg-gpio";
> +            reg = <0>;
> +            gpio-controller;
> +            #gpio-cells = <2>;
> +            #interrupt-cells = <2>;
> +            interrupt-controller;
> +            interrupt-parent = <&rpmsg_gpioa>;
> +          };
> +
> +          gpio@1 {
> +            compatible = "fsl,imx-rpmsg-gpio";
> +            reg = <1>;
> +            gpio-controller;
> +            #gpio-cells = <2>;
> +            #interrupt-cells = <2>;
> +            interrupt-controller;
> +            interrupt-parent = <&rpmsg_gpiob>;
> +          };
> +        };
> +
> +        rpmsg-i2c-channel {
> +          #address-cells = <1>;
> +          #size-cells = <0>;
> +
> +          i2c@0 {
> +            compatible = "fsl,imx-rpmsg-i2c";
> +            reg = <0>;
> +          };
> +        };
> +      };
>      };
>  ...
> -- 
> 2.43.0
>