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 <shenwei.wang@nxp.com>
---
 .../devicetree/bindings/gpio/gpio-rpmsg.yaml  | 49 +++++++++++++++++
 .../bindings/remoteproc/fsl,imx-rproc.yaml    | 54 +++++++++++++++++++
 2 files changed, 103 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/gpio/gpio-rpmsg.yaml

diff --git a/Documentation/devicetree/bindings/gpio/gpio-rpmsg.yaml b/Documentation/devicetree/bindings/gpio/gpio-rpmsg.yaml
new file mode 100644
index 000000000000..b3e1a5dbf731
--- /dev/null
+++ b/Documentation/devicetree/bindings/gpio/gpio-rpmsg.yaml
@@ -0,0 +1,49 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/gpio/gpio-rpmsg.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Generic GPIO driver over RPMSG
+
+maintainers:
+  - Shenwei Wang <shenwei.wang@nxp.com>
+
+description:
+  On an AMP platform, some GPIO controllers are exposed by the remote processor
+  through the RPMSG bus. The RPMSG GPIO transport protocol defines the packet
+  structure and communication flow between Linux and the remote firmware. Those
+  controllers are managed via this transport protocol.
+
+properties:
+  compatible:
+    oneOf:
+      - items:
+          - enum:
+              - fsl,rpmsg-gpio
+          - const: rpmsg-gpio
+      - const: rpmsg-gpio
+
+  reg:
+    maxItems: 1
+
+  "#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#
+
+unevaluatedProperties: false
diff --git a/Documentation/devicetree/bindings/remoteproc/fsl,imx-rproc.yaml b/Documentation/devicetree/bindings/remoteproc/fsl,imx-rproc.yaml
index 57d75acb0b5e..fd8e5a61a459 100644
--- a/Documentation/devicetree/bindings/remoteproc/fsl,imx-rproc.yaml
+++ b/Documentation/devicetree/bindings/remoteproc/fsl,imx-rproc.yaml
@@ -84,6 +84,33 @@ 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
+            $ref: /schemas/gpio/gpio-rpmsg.yaml#
+            unevaluatedProperties: false
+
+        required:
+          - '#address-cells'
+          - '#size-cells'
+
 required:
   - compatible
 
@@ -146,5 +173,32 @@ 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 = "rpmsg-gpio";
+            reg = <0>;
+            gpio-controller;
+            #gpio-cells = <2>;
+            #interrupt-cells = <2>;
+            interrupt-controller;
+            interrupt-parent = <&rpmsg_gpioa>;
+          };
+
+          gpio@1 {
+            compatible = "rpmsg-gpio";
+            reg = <1>;
+            gpio-controller;
+            #gpio-cells = <2>;
+            #interrupt-cells = <2>;
+            interrupt-controller;
+            interrupt-parent = <&rpmsg_gpiob>;
+          };
+        };
+      };
     };
 ...
-- 
2.43.0