[RFC PATCH 3/8] dt-bindings: mailbox: Add bindings for RISC-V SBI MPXY extension

[Anup Patel <apatel@ventanamicro.com>]

Add device tree bindings for the RISC-V SBI Message Proxy (MPXY)
extension as a mailbox controller.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
---
 .../bindings/mailbox/riscv,sbi-mpxy-mbox.yaml | 54 +++++++++++++++++++
 1 file changed, 54 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/mailbox/riscv,sbi-mpxy-mbox.yaml

diff --git a/Documentation/devicetree/bindings/mailbox/riscv,sbi-mpxy-mbox.yaml b/Documentation/devicetree/bindings/mailbox/riscv,sbi-mpxy-mbox.yaml
new file mode 100644
index 000000000000..8a05e089b710
--- /dev/null
+++ b/Documentation/devicetree/bindings/mailbox/riscv,sbi-mpxy-mbox.yaml
@@ -0,0 +1,54 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/mailbox/riscv,sbi-mpxy-mbox.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: RISC-V SBI Message Proxy (MPXY) extension based mailbox
+
+maintainers:
+  - Anup Patel <anup@brainfault.org>
+
+description: |
+  The RISC-V SBI Message Proxy (MPXY) extension [1] allows supervisor
+  software to send messages through the SBI implementation (M-mode
+  firmware or HS-mode hypervisor). The underlying message protocol
+  and message format used by the supervisor software could be some
+  other standard protocol compatible with the SBI MPXY extension
+  (such as RISC-V Platform Management Interface (RPMI) [2]).
+
+  ===========================================
+  References
+  ===========================================
+
+  [1] RISC-V Supervisor Binary Interface (SBI)
+      https://github.com/riscv-non-isa/riscv-sbi-doc/releases
+
+  [2] RISC-V Platform Management Interface (RPMI)
+      https://github.com/riscv-non-isa/riscv-rpmi/releases
+
+properties:
+  $nodename:
+    const: sbi-mpxy-mbox
+
+  compatible:
+    const: riscv,sbi-mpxy-mbox
+
+  "#mbox-cells":
+    const: 2
+    description:
+      The first cell specifies channel_id of the SBI MPXY channel,
+      the second cell specifies MSG_PROT_ID of the SBI MPXY channel
+
+required:
+  - compatible
+  - "#mbox-cells"
+
+additionalProperties: false
+
+examples:
+  - |
+    sbi-mpxy-mbox {
+          compatible = "riscv,sbi-mpxy-mbox";
+          #mbox-cells = <2>;
+    };
-- 
2.43.0