[PATCH v3 02/23] dt-bindings: mailbox: Add bindings for RPMI shared memory transport

Anup Patel
2025-05-11T13:40:22Z

Add device tree bindings for the common RISC-V Platform Management
Interface (RPMI) shared memory transport as a mailbox controller.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
---
.../mailbox/riscv,rpmi-shmem-mbox.yaml | 148 ++++++++++++++++++
1 file changed, 148 insertions(+)
create mode 100644 Documentation/devicetree/bindings/mailbox/riscv,rpmi-shmem-mbox.yaml

diff --git a/Documentation/devicetree/bindings/mailbox/riscv,rpmi-shmem-mbox.yaml b/Documentation/devicetree/bindings/mailbox/riscv,rpmi-shmem-mbox.yaml
new file mode 100644
index 000000000000..3194c066d952
--- /dev/null
+++ b/Documentation/devicetree/bindings/mailbox/riscv,rpmi-shmem-mbox.yaml
@@ -0,0 +1,148 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/mailbox/riscv,rpmi-shmem-mbox.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: RISC-V Platform Management Interface (RPMI) shared memory mailbox
+
+maintainers:
+ - Anup Patel <anup@brainfault.org>
+
+description: |
+ The RISC-V Platform Management Interface (RPMI) [1] defines a common shared
+ memory based RPMI transport. This RPMI shared memory transport integrates as
+ mailbox controller in the SBI implementation or supervisor software whereas
+ each RPMI service group is mailbox client in the SBI implementation and
+ supervisor software.
+
+ ===========================================
+ References
+ ===========================================
+
+ [1] RISC-V Platform Management Interface (RPMI)
+ https://github.com/riscv-non-isa/riscv-rpmi/releases
+
+properties:
+ compatible:
+ const: riscv,rpmi-shmem-mbox
+
+ reg:
+ oneOf:
+ - items:
+ - description: A2P request queue base address
+ - description: P2A acknowledgment queue base address
+ - description: P2A request queue base address
+ - description: A2P acknowledgment queue base address
+ - description: A2P doorbell address
+ - items:
+ - description: A2P request queue base address
+ - description: P2A acknowledgment queue base address
+ - description: P2A request queue base address
+ - description: A2P acknowledgment queue base address
+ - items:
+ - description: A2P request queue base address
+ - description: P2A acknowledgment queue base address
+ - description: A2P doorbell address
+ - items:
+ - description: A2P request queue base address
+ - description: P2A acknowledgment queue base address
+
+ reg-names:
+ oneOf:
+ - items:
+ - const: a2p-req
+ - const: p2a-ack
+ - const: p2a-req
+ - const: a2p-ack
+ - const: a2p-doorbell
+ - items:
+ - const: a2p-req
+ - const: p2a-ack
+ - const: p2a-req
+ - const: a2p-ack
+ - items:
+ - const: a2p-req
+ - const: p2a-ack
+ - const: a2p-doorbell
+ - items:
+ - const: a2p-req
+ - const: p2a-ack
+
+ interrupts:
+ maxItems: 1
+ description:
+ The RPMI shared memory transport supports wired interrupt specified by
+ this property as the P2A doorbell.
+
+ msi-parent:
+ description:
+ The RPMI shared memory transport supports P2A doorbell as a system MSI
+ and this property specifies the target MSI controller.
+
+ riscv,slot-size:
+ $ref: /schemas/types.yaml#/definitions/uint32
+ minimum: 64
+ description:
+ Power-of-2 RPMI slot size of the RPMI shared memory transport.
+
+ riscv,a2p-doorbell-value:
+ $ref: /schemas/types.yaml#/definitions/uint32
+ default: 0x1
+ description:
+ Value written to the 32-bit A2P doorbell register.
+
+ riscv,p2a-doorbell-sysmsi-index:
+ $ref: /schemas/types.yaml#/definitions/uint32
+ description:
+ The RPMI shared memory transport supports P2A doorbell as a system MSI
+ and this property specifies system MSI index to be used for configuring
+ the P2A doorbell MSI.
+
+ "#mbox-cells":
+ const: 1
+ description:
+ The first cell specifies RPMI service group ID.
+
+required:
+ - compatible
+ - reg
+ - reg-names
+ - riscv,slot-size
+ - "#mbox-cells"
+
+anyOf:
+ - required:
+ - interrupts
+ - required:
+ - msi-parent
+
+additionalProperties: false
+
+examples:
+ - |
+ // Example 1 (RPMI shared memory with only 2 queues):
+ mailbox@10080000 {
+ compatible = "riscv,rpmi-shmem-mbox";
+ reg = <0x10080000 0x10000>,
+ <0x10090000 0x10000>;
+ reg-names = "a2p-req", "p2a-ack";
+ msi-parent = <&imsic_mlevel>;
+ riscv,slot-size = <64>;
+ #mbox-cells = <1>;
+ };
+ - |
+ // Example 2 (RPMI shared memory with only 4 queues):
+ mailbox@10001000 {
+ compatible = "riscv,rpmi-shmem-mbox";
+ reg = <0x10001000 0x800>,
+ <0x10001800 0x800>,
+ <0x10002000 0x800>,
+ <0x10002800 0x800>,
+ <0x10003000 0x4>;
+ reg-names = "a2p-req", "p2a-ack", "p2a-req", "a2p-ack", "a2p-doorbell";
+ msi-parent = <&imsic_mlevel>;
+ riscv,slot-size = <64>;
+ riscv,a2p-doorbell-value = <0x00008000>;
+ #mbox-cells = <1>;
+ };
--
2.43.0