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Subject: [PATCH v4 02/14] dt-bindings: Add binding for gunyah hypervisor
Date:   Wed, 28 Sep 2022 12:56:21 -0700
Message-ID: <20220928195633.2348848-3-quic_eberman@quicinc.com>
In-Reply-To: <20220928195633.2348848-1-quic_eberman@quicinc.com>
References: <20220928195633.2348848-1-quic_eberman@quicinc.com>
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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@quicinc.com>
---
 .../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..f0a14101e2fd
--- /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@quicinc.com>
+  - Elliot Berman <quic_eberman@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@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 e88ebb7cbcb8..5b6b6f25c604 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -8885,6 +8885,7 @@ M:	Elliot Berman <quic_eberman@quicinc.com>
 M:	Murali Nalajala <quic_mnalajal@quicinc.com>
 L:	linux-arm-msm@vger.kernel.org
 S:	Supported
+F:	Documentation/devicetree/bindings/firmware/gunyah-hypervisor.yaml
 F:	Documentation/virt/gunyah/
 
 HABANALABS PCI DRIVER
-- 
2.25.1