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

On Tue, 22 Sept 2026 at 13:44, Francesco Valla [off-list ref] wrote:

On Tue, Sep 22, 2026 at 09:40:31AM -0600, Mathieu Poirier wrote:

quoted

On Wed, Sep 16, 2026 at 11:10:53PM +0200, Francesco Valla wrote:

quoted

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 <redacted>
---
 .../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.

AFAIK yes, because the rproc_get_vdev_fwnode() helpers search for indexed
child nodes using the 'reg' property, not the node name. This I believe
is the preferred way of doing things.

quoted

quoted

+              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.

This is because both GPIO and I2C bindings are already defined - even if
not used in the devicetree files part of the kernel tree.

Moving forward, I plan to submit at least the spi-virtio bindings as a
separate patch set, as they can be used independently of this one.

I suggest you leave spi-virtio out of this patchset.  That way we can
concentrate on doing only one thing.

quoted

quoted

+              };
+          };
+      };
+    };
+...

--
2.55.0

Regards,
Francesco