[PATCH RFC 01/15] dt-bindings: arm: Add MPAM MSC binding

From: Rob Herring <[email protected]>

The binding is designed around the assumption that an MSC will be a
sub-block of something else such as a memory controller, cache controller,
or IOMMU. However, it's certainly possible a design does not have that
association or has a mixture of both, so the binding illustrates how we can
support that with RIS child nodes.

A key part of MPAM is we need to know about all of the MSCs in the system
before it can be enabled. This drives the need for the genericish
'arm,mpam-msc' compatible. Though we can't assume an MSC is accessible
until a h/w specific driver potentially enables the h/w.

Cc: James Morse <[email protected]>
Signed-off-by: Rob Herring <[email protected]>
Signed-off-by: James Morse <[email protected]>
Signed-off-by: Yin Li <[email protected]>
---
 .../devicetree/bindings/arm/arm,mpam-msc.yaml      | 199 +++++++++++++++++++++
 1 file changed, 199 insertions(+)

diff --git a/Documentation/devicetree/bindings/arm/arm,mpam-msc.yaml b/Documentation/devicetree/bindings/arm/arm,mpam-msc.yaml
new file mode 100644
index 000000000000..53a6fdbbf05f
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/arm,mpam-msc.yaml
@@ -0,0 +1,199 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/arm/arm,mpam-msc.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Arm Memory System Resource Partitioning and Monitoring (MPAM)
+
+description: |
+  The Arm MPAM specification can be found here:
+
+  https://developer.arm.com/documentation/ddi0598/latest
+
+maintainers:
+  - Rob Herring <[email protected]>
+
+properties:
+  compatible:
+    items:
+      - const: arm,mpam-msc                   # Further details are discoverable
+      - const: arm,mpam-memory-controller-msc
+
+  reg:
+    maxItems: 1
+    description: A memory region containing registers as defined in the MPAM
+      specification.
+
+  interrupts:
+    minItems: 1
+    items:
+      - description: error (optional)
+      - description: overflow (optional, only for monitoring)
+
+  interrupt-names:
+    oneOf:
+      - items:
+          - enum: [ error, overflow ]
+      - items:
+          - const: error
+          - const: overflow
+
+  arm,not-ready-us:
+    description: The maximum time in microseconds for monitoring data to be
+      accurate after a settings change. For more information, see the
+      Not-Ready (NRDY) bit description in the MPAM specification.
+
+  numa-node-id: true # see NUMA binding
+
+  '#address-cells':
+    const: 1
+
+  '#size-cells':
+    const: 0
+
+patternProperties:
+  '^ris@[0-9a-f]+$':
+    type: object
+    additionalProperties: false
+    description:
+      RIS nodes for each resource instance in an MSC. These nodes are required
+      for each resource instance implementing known MPAM controls
+
+    properties:
+      compatible:
+        enum:
+          - arm,mpam-cache
+          # Memory bandwidth
+          - arm,mpam-memory
+
+      reg:
+        minimum: 0
+        maximum: 0xf
+
+      cpus:
+        description:
+          Phandle(s) to the CPU node(s) this RIS belongs to. By default, the parent
+          device's affinity is used.
+
+      arm,mpam-device:
+        $ref: /schemas/types.yaml#/definitions/phandle
+        description:
+          By default, the MPAM enabled device associated with a RIS is the MSC's
+          parent node. It is possible for each RIS to be associated with different
+          devices in which case 'arm,mpam-device' should be used.
+
+    required:
+      - compatible
+      - reg
+
+required:
+  - compatible
+  - reg
+
+dependencies:
+  interrupts: [ interrupt-names ]
+
+additionalProperties: false
+
+examples:
+  - |
+    L3: cache-controller@30000000 {
+        compatible = "arm,dsu-l3-cache", "cache";
+        cache-level = <3>;
+        cache-unified;
+
+        ranges = <0x0 0x30000000 0x800000>;
+        #address-cells = <1>;
+        #size-cells = <1>;
+
+        msc@10000 {
+            compatible = "arm,mpam-msc";
+
+            reg = <0x10000 0x2000>;
+            interrupts = <1>, <2>;
+            interrupt-names = "error", "overflow";
+            arm,not-ready-us = <1>;
+            /* CPU affinity implied by parent cache node  */
+        };
+    };
+
+    mem: memory-controller@20000 {
+        compatible = "foo,a-memory-controller";
+        reg = <0x20000 0x1000>;
+
+        #address-cells = <1>;
+        #size-cells = <1>;
+        ranges;
+
+        msc@21000 {
+            compatible = "arm,mpam-memory-controller-msc", "arm,mpam-msc";
+            reg = <0x21000 0x1000>;
+            interrupts = <3>;
+            interrupt-names = "error";
+            arm,not-ready-us = <1>;
+            numa-node-id = <1>;
+        };
+    };
+
+    iommu@40000 {
+        reg = <0x40000 0x1000>;
+
+        ranges;
+        #address-cells = <1>;
+        #size-cells = <1>;
+
+        msc@41000 {
+            compatible = "arm,mpam-msc";
+            reg = <0 0x1000>;
+            interrupts = <5>, <6>;
+            interrupt-names = "error", "overflow";
+            arm,not-ready-us = <1>;
+
+            #address-cells = <1>;
+            #size-cells = <0>;
+
+            ris@2 {
+                compatible = "arm,mpam-cache";
+                reg = <0>;
+                // TODO: How to map to device(s)?
+            };
+        };
+    };
+
+    msc@80000 {
+        compatible = "foo,a-standalone-msc";
+        reg = <0x80000 0x1000>;
+
+        clocks = <&clks 123>;
+
+        ranges;
+        #address-cells = <1>;
+        #size-cells = <1>;
+
+        msc@10000 {
+            compatible = "arm,mpam-msc";
+
+            reg = <0x10000 0x2000>;
+            interrupts = <7>;
+            interrupt-names = "overflow";
+            arm,not-ready-us = <1>;
+
+            #address-cells = <1>;
+            #size-cells = <0>;
+
+            ris@0 {
+                compatible = "arm,mpam-cache";
+                reg = <0>;
+                arm,mpam-device = <&L2_0>;
+            };
+
+            ris@1 {
+                compatible = "arm,mpam-memory";
+                reg = <1>;
+                arm,mpam-device = <&mem>;
+            };
+        };
+    };
+
+...

-- 
2.34.1