Re: [PATCH RFC 08/12] dt-bindings: remoteproc: add remoteproc-virtio

[Mathieu Poirier <mathieu.poirier@linaro.org>]

On Wed, Sep 16, 2026 at 11:10:53PM +0200, Francesco Valla wrote:
> Add a new binding to describe remoteproc-provided virtio devices; while
> these are discovered through a resource table parsed by the remoteproc
> infrastructure at runtime, their description can be needed to probe
> non-discoverable buses (such as I2C) or to link consumers and suppliers.
> 
> Each vdev is described by a dedicated "group" node, which then includes
> a virtio-device node, which binding is already existent and used by
> virtio-mmio. Each vdev shall be stattically linked to a "group" node
> using its index inside the resource table as the reg property of the
> node; this permits to have multiple instances of the same type of
> device.
> 
> The binding is intended to be generic and adopted by any remoteproc
> provider.
> 
> Signed-off-by: Francesco Valla <francesco@valla.it>
> ---
>  .../bindings/remoteproc/remoteproc-virtio.yaml     | 89 ++++++++++++++++++++++
>  1 file changed, 89 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/remoteproc/remoteproc-virtio.yaml b/Documentation/devicetree/bindings/remoteproc/remoteproc-virtio.yaml
> new file mode 100644
> index 000000000000..c4a0d84b1460
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/remoteproc/remoteproc-virtio.yaml
> @@ -0,0 +1,89 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/remoteproc/remoteproc-virtio.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Virtio devices over remoteproc
> +
> +description: |
> +  Virtio devices ("vdevs") can be exposed using the remoteproc infrastructure
> +  and its resource table. For some of them, a device tree node might be needed
> +  to describe remote undiscoverable hardware and/or connect consumers and
> +  providers.
> +
> +maintainers:
> +  - Francesco Valla <francesco@valla.it>
> +
> +properties:
> +  virtio:
> +    description: Contains a group of Virtio devices exposed by the remoteproc.
> +
> +    properties:
> +      '#address-cells':
> +        const: 1
> +
> +      '#size-cells':
> +        const: 0
> +
> +    patternProperties:
> +      "^vdev@[0-9a-f]+$":
> +        type: object
> +
> +        properties:
> +          reg:
> +            description: Virtio device index inside the resource table.
> +            maxItems: 1
> +
> +        additionalProperties:
> +          type: object
> +          $ref: /schemas/virtio/virtio-device.yaml
> +          maxItems: 1
> +
> +        required:
> +          - reg
> +
> +    additionalProperties: false
> +
> +    required:
> +      - '#address-cells'
> +      - '#size-cells'
> +
> +additionalProperties: true
> +
> +examples:
> +  - |
> +    remoteproc-cm33 {
> +      virtio {
> +          #address-cells = <1>;
> +          #size-cells = <0>;
> +
> +          vdev@0 {
> +              reg = <0>;
> +

Do we need the 'reg' since we already have vdev@X?  I'll let the DT people
provide their input on this.

> +              gpio {
> +                  compatible = "virtio,device29";
> +
> +                  gpio-controller;
> +                  #gpio-cells = <2>;
> +              };
> +          };
> +
> +          vdev@1 {
> +              reg = <1>;
> +
> +              i2c {
> +                  compatible = "virtio,device22";
> +
> +                  #address-cells = <1>;
> +                  #size-cells = <0>;
> +
> +                  eeprom@50 {
> +                      compatible = "atmel,24c1025";
> +                      reg = <0x50>;
> +                  };

The previous patch introduced bindings for virtio SPI while the above two are
for GPIO and I2c, which is very confusing.  I suggest you pick one and apply
everywhere.

> +              };
> +          };
> +      };
> +    };
> +...
> 
> -- 
> 2.55.0
>