linux-kernel - Re: [PATCH v2 2/4] dt-bindings: cpufreq: apple,soc-cpufreq: Add binding for Apple SoC cpufreq

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Date:   Mon, 16 May 2022 17:49:32 -0500
From:   Rob Herring <robh@...nel.org>
To:     Hector Martin <marcan@...can.st>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Sven Peter <sven@...npeter.dev>,
        Alyssa Rosenzweig <alyssa@...enzweig.io>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Stephen Boyd <sboyd@...nel.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Marc Zyngier <maz@...nel.org>,
        Mark Kettenis <mark.kettenis@...all.nl>,
        linux-arm-kernel@...ts.infradead.org, linux-pm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/4] dt-bindings: cpufreq: apple,soc-cpufreq: Add
 binding for Apple SoC cpufreq

On Wed, May 04, 2022 at 04:51:51PM +0900, Hector Martin wrote:
> This binding represents the cpufreq/DVFS hardware present in Apple SoCs.
> The hardware has an independent controller per CPU cluster, but we
> represent them as a single cpufreq node since there can only be one
> systemwide cpufreq device (and since in the future, interactions with
> memory controller performance states will also involve cooperation
> between multiple frequency domains).
> 
> Signed-off-by: Hector Martin <marcan@...can.st>
> ---
>  .../bindings/cpufreq/apple,soc-cpufreq.yaml   | 121 ++++++++++++++++++
>  1 file changed, 121 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/cpufreq/apple,soc-cpufreq.yaml
> 
> diff --git a/Documentation/devicetree/bindings/cpufreq/apple,soc-cpufreq.yaml b/Documentation/devicetree/bindings/cpufreq/apple,soc-cpufreq.yaml
> new file mode 100644
> index 000000000000..f398c1bd5de5
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/cpufreq/apple,soc-cpufreq.yaml
> @@ -0,0 +1,121 @@
> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/cpufreq/apple,soc-cpufreq.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Apple SoC cpufreq device
> +
> +maintainers:
> +  - Hector Martin <marcan@...can.st>
> +
> +description: |
> +  Apple SoCs (e.g. M1) have a per-cpu-cluster DVFS controller that is part of
> +  the cluster management register block. This binding uses the standard
> +  operating-points-v2 table to define the CPU performance states, with the
> +  opp-level property specifying the hardware p-state index for that level.
> +
> +properties:
> +  compatible:
> +    items:
> +      - enum:
> +          - apple,t8103-soc-cpufreq
> +          - apple,t6000-soc-cpufreq
> +      - const: apple,soc-cpufreq
> +
> +  reg:
> +    minItems: 1
> +    maxItems: 6
> +    description: One register region per CPU cluster DVFS controller
> +
> +  reg-names:
> +    minItems: 1
> +    items:
> +      - const: cluster0
> +      - const: cluster1
> +      - const: cluster2
> +      - const: cluster3
> +      - const: cluster4
> +      - const: cluster5
> +
> +  '#freq-domain-cells':
> +    const: 1

Copied QCom it seems. Use 'performance-domains' which is the common 
binding.

> +
> +required:
> +  - compatible
> +  - reg
> +  - reg-names
> +  - '#freq-domain-cells'
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    // This example shows a single CPU per domain and 2 domains,
> +    // with two p-states per domain.
> +    // Shipping hardware has 2-4 CPUs per domain and 2-6 domains.
> +    cpus {
> +      #address-cells = <2>;
> +      #size-cells = <0>;
> +
> +      cpu@0 {
> +        compatible = "apple,icestorm";
> +        device_type = "cpu";
> +        reg = <0x0 0x0>;
> +        operating-points-v2 = <&ecluster_opp>;
> +        apple,freq-domain = <&cpufreq_hw 0>;
> +      };
> +
> +      cpu@...00 {
> +        compatible = "apple,firestorm";
> +        device_type = "cpu";
> +        reg = <0x0 0x10100>;
> +        operating-points-v2 = <&pcluster_opp>;
> +        apple,freq-domain = <&cpufreq_hw 1>;
> +      };
> +    };
> +
> +    ecluster_opp: opp-table-0 {
> +      compatible = "operating-points-v2";
> +      opp-shared;
> +
> +      opp01 {
> +        opp-hz = /bits/ 64 <600000000>;
> +        opp-level = <1>;
> +        clock-latency-ns = <7500>;
> +      };
> +      opp02 {
> +        opp-hz = /bits/ 64 <972000000>;
> +        opp-level = <2>;
> +        clock-latency-ns = <22000>;
> +      };
> +    };
> +
> +    pcluster_opp: opp-table-1 {
> +      compatible = "operating-points-v2";
> +      opp-shared;
> +
> +      opp01 {
> +        opp-hz = /bits/ 64 <600000000>;
> +        opp-level = <1>;
> +        clock-latency-ns = <8000>;
> +      };
> +      opp02 {
> +        opp-hz = /bits/ 64 <828000000>;
> +        opp-level = <2>;
> +        clock-latency-ns = <19000>;
> +      };
> +    };
> +
> +    soc {
> +      #address-cells = <2>;
> +      #size-cells = <2>;
> +
> +      cpufreq_hw: cpufreq@...e20000 {
> +        compatible = "apple,t8103-soc-cpufreq", "apple,soc-cpufreq";
> +        reg = <0x2 0x10e20000 0 0x1000>,
> +              <0x2 0x11e20000 0 0x1000>;
> +        reg-names = "cluster0", "cluster1";
> +        #freq-domain-cells = <1>;
> +      };
> +    };
> -- 
> 2.35.1
> 
>