[PATCH v6 7/8] dt-bindings: riscv: Add binding for CBQRI controllers

Document the device tree binding for RISC-V CBQRI capacity and bandwidth
controllers. Each controller is named by a device-specific compatible
followed by the generic compatible. The binding also describes the
common riscv,cbqri-rcid and riscv,cbqri-mcid properties, and the
optional riscv,cbqri-cache phandle that links a capacity controller to
the cache whose capacity it allocates.

Assisted-by: Claude:claude-opus-4-8
Reviewed-by: Conor Dooley <[email protected]>
Co-developed-by: Adrien Ricciardi <[email protected]>
Signed-off-by: Adrien Ricciardi <[email protected]>
Signed-off-by: Drew Fustini <[email protected]>
---
 .../devicetree/bindings/riscv/riscv,cbqri.yaml     | 97 ++++++++++++++++++++++
 MAINTAINERS                                        |  1 +
 2 files changed, 98 insertions(+)

diff --git a/Documentation/devicetree/bindings/riscv/riscv,cbqri.yaml b/Documentation/devicetree/bindings/riscv/riscv,cbqri.yaml
new file mode 100644
index 000000000000..62d547a0cb96
--- /dev/null
+++ b/Documentation/devicetree/bindings/riscv/riscv,cbqri.yaml
@@ -0,0 +1,97 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/riscv/riscv,cbqri.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: RISC-V Capacity and Bandwidth QoS Register Interface (CBQRI) controller
+
+description: |
+  The RISC-V CBQRI specification defines capacity-controller and
+  bandwidth-controller register blocks that allocate cache capacity and memory
+  bandwidth to resource-control IDs (RCIDs) and monitor usage per
+  monitoring-counter ID (MCID):
+  https://github.com/riscv-non-isa/riscv-cbqri/blob/main/riscv-cbqri.pdf
+
+  Allocation and monitoring share one register block, and a controller may
+  implement either or both. A driver discovers which at runtime from the
+  capabilities register, so the compatible names only the controller type. It
+  does not distinguish allocation-only, monitoring-only or combined
+  controllers, and no property declares monitoring support.
+
+maintainers:
+  - Drew Fustini <[email protected]>
+
+properties:
+  compatible:
+    oneOf:
+      - items:
+          - enum:
+              - tenstorrent,ascalon-shared-cache-controller
+          - const: riscv,cbqri-capacity-controller
+      - items:
+          - {}
+          - const: riscv,cbqri-bandwidth-controller
+
+  reg:
+    maxItems: 1
+    description:
+      The CBQRI controller register block.
+
+  riscv,cbqri-rcid:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description:
+      The maximum number of RCIDs the controller supports. RCIDs are the
+      resource-control IDs that allocation operations target.
+
+  riscv,cbqri-mcid:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description:
+      The maximum number of MCIDs the controller supports. MCIDs are the
+      monitoring-counter IDs that usage-monitoring operations target. Present
+      on controllers that implement monitoring.
+
+  riscv,cbqri-cache:
+    $ref: /schemas/types.yaml#/definitions/phandle
+    description:
+      Phandle to the cache node whose capacity this controller allocates.
+      Applies to capacity controllers that back a CPU cache. The cache level
+      and the harts sharing it are taken from that node's cache topology.
+
+required:
+  - compatible
+  - reg
+
+allOf:
+  - if:
+      properties:
+        compatible:
+          contains:
+            const: tenstorrent,ascalon-shared-cache-controller
+    then:
+      required:
+        - riscv,cbqri-rcid
+        - riscv,cbqri-cache
+
+additionalProperties: false
+
+examples:
+  - |
+    l2_cache: l2-cache {
+        compatible = "cache";
+        cache-level = <2>;
+        cache-unified;
+        cache-size = <0xc00000>;
+        cache-sets = <512>;
+        cache-block-size = <64>;
+    };
+
+    qos-controller@a21a00c0 {
+        compatible = "tenstorrent,ascalon-shared-cache-controller",
+                     "riscv,cbqri-capacity-controller";
+        reg = <0xa21a00c0 0xf40>;
+        riscv,cbqri-rcid = <16>;
+        riscv,cbqri-cache = <&l2_cache>;
+    };
+
+...
diff --git a/MAINTAINERS b/MAINTAINERS
index b9bded8d3dd6..7acdab42e9c5 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -23363,6 +23363,7 @@ M:	Drew Fustini <[email protected]>
 R:	yunhui cui <[email protected]>
 L:	[email protected]
 S:	Supported
+F:	Documentation/devicetree/bindings/riscv/riscv,cbqri.yaml
 F:	arch/riscv/include/asm/qos.h
 F:	arch/riscv/include/asm/resctrl.h
 F:	arch/riscv/kernel/qos.c

-- 
2.43.0