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charset=us-ascii Content-Disposition: inline In-Reply-To: <20250711183648.30766-12-james.morse@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250711_224321_357781_2BC6569F X-CRM114-Status: GOOD ( 32.01 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Jul 11, 2025 at 06:36:23PM +0000, James Morse wrote: > From: Rob Herring > > 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 > Signed-off-by: Rob Herring > Signed-off-by: James Morse > --- > .../devicetree/bindings/arm/arm,mpam-msc.yaml | 227 ++++++++++++++++++ > 1 file changed, 227 insertions(+) > create mode 100644 Documentation/devicetree/bindings/arm/arm,mpam-msc.yaml Is there any DT based h/w using this? I'm not aware of any. I would prefer not merging this until there is. I have little insight whether these genericish compatibles will be sufficient, but I have lots of experience to say they won't be. I would also suspect that if anyone has started using this, they've just extended/modified it however they wanted and no feedback got to me. > 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..9d542ecb1a7d > --- /dev/null > +++ b/Documentation/devicetree/bindings/arm/arm,mpam-msc.yaml > @@ -0,0 +1,227 @@ > +# 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 > + > +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: | '|' can be dropped. > + RIS nodes for each RIS in an MSC. These nodes are required for each RIS > + implementing known MPAM controls > + > + properties: > + compatible: > + enum: > + # Bulk storage for cache > + - arm,mpam-cache > + # Memory bandwidth > + - arm,mpam-memory > + > + reg: > + minimum: 0 > + maximum: 0xf > + > + cpus: > + $ref: '/schemas/types.yaml#/definitions/phandle-array' Don't need the type. It's in the core schemas now. > + 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' Don't need quotes. This should be a warning, but no testing happened because the DT list and maintainers weren't CCed. > + 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: > + - | > + /* > + cpus { > + cpu@0 { > + next-level-cache = <&L2_0>; > + }; > + cpu@100 { > + next-level-cache = <&L2_1>; > + }; > + }; > + */ > + L2_0: cache-controller-0 { > + compatible = "cache"; > + cache-level = <2>; > + cache-unified; > + next-level-cache = <&L3>; > + > + }; > + > + L2_1: cache-controller-1 { > + compatible = "cache"; > + cache-level = <2>; > + cache-unified; > + next-level-cache = <&L3>; > + > + }; All the above should be dropped. Not part of this binding. > + > + L3: cache-controller@30000000 { > + compatible = "arm,dsu-l3-cache", "cache"; Pretty sure this is a warning because that compatible doesn't exist. > + cache-level = <3>; > + cache-unified; > + > + ranges = <0x0 0x30000000 0x800000>; > + #address-cells = <1>; > + #size-cells = <1>; > + > + msc@10000 { > + compatible = "arm,mpam-msc"; > + > + /* CPU affinity implied by parent cache node's */ > + reg = <0x10000 0x2000>; > + interrupts = <1>, <2>; > + interrupt-names = "error", "overflow"; > + arm,not-ready-us = <1>; > + }; > + }; > + > + 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>; > + }; > + }; > + }; > + > +... > -- > 2.39.5 >