[PATCH v3 03/12] dt-bindings: Add binding for gunyah hypervisor

[Elliot Berman]

When Linux is booted as a guest under the Gunyah hypervisor, the Gunyah
Resource Manager applies a devicetree overlay describing the virtual
platform configuration of the guest VM, such as the message queue
capability IDs for communicating with the Resource Manager. This
information is not otherwise discoverable by a VM: the Gunyah hypervisor
core does not provide a direct interface to discover capability IDs nor
a way to communicate with RM without having already known the
corresponding message queue capability ID. Add the DT bindings that
Gunyah adheres for the hypervisor node and message queues.

Signed-off-by: Elliot Berman <quic_eberman at quicinc.com>
---
Changes since v2:
 - Add newlines as suggested
 - Fixed typo in example (gunyah-resource-mgr at 0 -> gunyah-resource-mgr at 1)

 .../bindings/firmware/gunyah-hypervisor.yaml  | 87 +++++++++++++++++++
 MAINTAINERS                                   |  1 +
 2 files changed, 88 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/firmware/gunyah-hypervisor.yaml

diff --git a/Documentation/devicetree/bindings/firmware/gunyah-hypervisor.yaml b/Documentation/devicetree/bindings/firmware/gunyah-hypervisor.yaml
new file mode 100644
index 000000000000..8edcd3915f3c
--- /dev/null
+++ b/Documentation/devicetree/bindings/firmware/gunyah-hypervisor.yaml
@@ -0,0 +1,87 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/firmware/gunyah-hypervisor.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Gunyah Hypervisor
+
+maintainers:
+  - Murali Nalajala <quic_mnalajal at quicinc.com>
+  - Elliot Berman <quic_eberman at quicinc.com>
+
+description: |+
+  On systems which support devicetree, Gunyah generates and overlays a deviceetree overlay which
+  describes the basic configuration of the hypervisor. Virtual machines use this information to determine
+  the capability IDs of the message queues used to communicate with the Gunyah Resource Manager.
+  See also: https://github.com/quic/gunyah-resource-manager/blob/develop/src/vm_creation/dto_construct.c
+
+properties:
+  compatible:
+    - items:
+        - const: gunyah-hypervisor-1.0
+        - const: gunyah-hypervisor
+
+  "#address-cells":
+    description: Number of cells needed to represent 64-bit capability IDs.
+    const: 2
+
+  "#size-cells":
+    description: must be 0, because capability IDs are not memory address
+                  ranges and do not have a size.
+    const: 0
+
+patternProperties:
+  "^gunyah-resource-mgr(@.*)?":
+    type: object
+    description:
+      Resource Manager node which is required to communicate to Resource
+      Manager VM using Gunyah Message Queues.
+
+    properties:
+      compatible:
+        - items:
+            - const: gunyah-resource-manager-1-0
+            - const: gunyah-resource-manager
+
+      reg:
+        items:
+          - description: Gunyah capability ID of the TX message queue
+          - description: Gunyah capability ID of the RX message queue
+
+      interrupts:
+        items:
+          - description: Interrupt for the TX message queue
+          - description: Interrupt for the RX message queue
+
+    additionalProperties: false
+
+    required:
+      - compatible
+      - reg
+      - interrupts
+
+additionalProperties: false
+
+required:
+  - compatible
+  - "#address-cells"
+  - "#size-cells"
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+
+    hypervisor {
+        #address-cells = <2>;
+        #size-cells = <0>;
+        compatible = "gunyah-hypervisor-1.0", "gunyah-hypervisor";
+
+        gunyah-resource-mgr at 0 {
+            compatible = "gunyah-resource-manager-1-0", "gunyah-resource-manager";
+            interrupts = <GIC_SPI 3 IRQ_TYPE_EDGE_RISING>, /* TX full IRQ */
+                         <GIC_SPI 4 IRQ_TYPE_EDGE_RISING>; /* RX empty IRQ */
+            reg = <0x00000000 0x00000000>, <0x00000000 0x00000001>;
+                  /* TX, RX cap ids */
+        };
+    };
diff --git a/MAINTAINERS b/MAINTAINERS
index 24d1660bbafa..77bb7833d561 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -8739,6 +8739,7 @@ M:	Elliot Berman <quic_eberman at quicinc.com>
 M:	Murali Nalajala <quic_mnalajal at quicinc.com>
 L:	linux-arm-msm at vger.kernel.org
 S:	Supported
+F:	Documentation/devicetree/bindings/firmware/gunyah-hypervisor.yaml
 F:	Documentation/virt/gunyah/
 
 HABANALABS PCI DRIVER
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2.25.1