Re: [PATCH 1/4] dt-bindings: remoteproc: imx_rproc: Add "rpmsg" subnode support

[Rob Herring <robh@kernel.org>]

On Mon, Aug 18, 2025 at 03:44:17PM -0500, 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.

How is each channel addressed? Are they really grouped by type first 
(i2c, gpio, etc.) then an address within the group? Or is there some 
flat channel numbering? If the latter, then the addresses in the DT 
shoulc match the channel number.

> 
> Signed-off-by: Shenwei Wang <shenwei.wang@nxp.com>
> ---
>  .../bindings/remoteproc/fsl,imx-rproc.yaml    | 117 ++++++++++++++++++
>  1 file changed, 117 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/remoteproc/fsl,imx-rproc.yaml b/Documentation/devicetree/bindings/remoteproc/fsl,imx-rproc.yaml
> index 57d75acb0b5e..a105aac798d0 100644
> --- a/Documentation/devicetree/bindings/remoteproc/fsl,imx-rproc.yaml
> +++ b/Documentation/devicetree/bindings/remoteproc/fsl,imx-rproc.yaml
> @@ -84,6 +84,86 @@ 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:
> +      '#address-cells':
> +        const: 1
> +
> +      '#size-cells':
> +        const: 0
> +
> +      rpmsg-io-channel:
> +        type: object
> +        unevaluatedProperties: 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
> +
> +            required:
> +              - compatible
> +              - reg
> +
> +            allOf:
> +              - $ref: /schemas/gpio/gpio.yaml#
> +              - $ref: /schemas/interrupt-controller.yaml#

This is not needed nor sufficient. You need to define the cell sizes for 
gpio and interrupt cells.

> +
> +        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 +226,42 @@ 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
>