linux-kernel - Re: [RFC PATCH 3/9] dt-bindings: clock: Add apple,cluster-clk binding

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Date:   Tue, 12 Oct 2021 10:51:09 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>
To:     Hector Martin <marcan@...can.st>,
        linux-arm-kernel@...ts.infradead.org
Cc:     Alyssa Rosenzweig <alyssa@...enzweig.io>,
        Sven Peter <sven@...npeter.dev>, Marc Zyngier <maz@...nel.org>,
        Mark Kettenis <mark.kettenis@...all.nl>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Catalin Marinas <catalin.marinas@....com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Kevin Hilman <khilman@...nel.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        linux-clk@...r.kernel.org, devicetree@...r.kernel.org,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 3/9] dt-bindings: clock: Add apple,cluster-clk binding

On 11/10/2021 18:57, Hector Martin wrote:
> This device represents the CPU performance state switching mechanism as
> a clock controller, to be used with the standard cpufreq-dt
> infrastructure.
> 
> Signed-off-by: Hector Martin <marcan@...can.st>
> ---
>  .../bindings/clock/apple,cluster-clk.yaml     | 115 ++++++++++++++++++
>  1 file changed, 115 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/clock/apple,cluster-clk.yaml
> 
> diff --git a/Documentation/devicetree/bindings/clock/apple,cluster-clk.yaml b/Documentation/devicetree/bindings/clock/apple,cluster-clk.yaml
> new file mode 100644
> index 000000000000..9a8b863dadc0
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/clock/apple,cluster-clk.yaml
> @@ -0,0 +1,115 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/clock/apple,cluster-clk.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: CPU cluster frequency scaling for Apple SoCs
> +
> +maintainers:
> +  - Hector Martin <marcan@...can.st>
> +
> +description: |
> +  Apple SoCs control CPU cluster frequencies by using a performance state
> +  index. This node represents the feature as a clock controller, and uses
> +  a reference to the CPU OPP table to translate clock frequencies into
> +  performance states. This allows the CPUs to use the standard cpufreq-dt
> +  mechanism for frequency scaling.
> +
> +properties:
> +  compatible:
> +    items:
> +      - enum:
> +          - apple,t8103-cluster-clk
> +      - const: apple,cluster-clk
> +
> +  reg:
> +    maxItems: 1
> +
> +  '#clock-cells':
> +    const: 0
> +
> +  operating-points-v2:
> +    $ref: /schemas/types.yaml#/definitions/phandle-array
> +    description:
> +      A reference to the OPP table used for the CPU cluster controlled by this
> +      device instance. The table should contain an `opp-level` property for
> +      every OPP, which represents the p-state index used by the hardware to
> +      represent this performance level.
> +
> +      OPPs may also have a `required-opps` property (see power-domains).
> +
> +  power-domains:
> +    maxItems: 1
> +    description:
> +      An optional reference to a power domain provider that links its
> +      performance state to the CPU cluster performance state. This is typically
> +      a memory controller. If set, the `required-opps` property in the CPU
> +      frequency OPP nodes will be used to change the performance state of this
> +      provider state in tandem with CPU frequency changes.
> +
> +required:
> +  - compatible
> +  - reg
> +  - '#clock-cells'
> +  - operating-points-v2
> +
> +additionalProperties: false
> +
> +

One line break.

> +examples:
> +  - |
> +    pcluster_opp: opp-table-1 {
> +        compatible = "operating-points-v2";
> +        opp-shared;
> +
> +        opp01 {
> +            opp-hz = /bits/ 64 <600000000>;
> +            opp-microvolt = <781000>;
> +            opp-level = <1>;
> +            clock-latency-ns = <8000>;
> +            required-opps = <&mcc_lowperf>;
> +        };
> +        /* intermediate p-states omitted */
> +        opp15 {
> +            opp-hz = /bits/ 64 <3204000000>;
> +            opp-microvolt = <1081000>;
> +            opp-level = <15>;
> +            clock-latency-ns = <56000>;
> +            required-opps = <&mcc_highperf>;
> +        };
> +    };
> +
> +    mcc_opp: opp-table-2 {
> +        compatible = "operating-points-v2";

Wrong compatible.

> +
> +        mcc_lowperf: opp0 {
> +            opp-level = <0>;
> +            apple,memory-perf-config = <0x813057f 0x1800180>;
> +        };
> +        mcc_highperf: opp1 {
> +            opp-level = <1>;
> +            apple,memory-perf-config = <0x133 0x55555340>;
> +        };
> +    };
> +
> +    soc {
> +        #address-cells = <2>;
> +        #size-cells = <2>;
> +
> +        mcc: memory-controller@...200000 {
> +            compatible = "apple,t8103-mcc", "apple,mcc";
> +            #power-domain-cells = <0>;
> +            reg = <0x2 0x200000 0x0 0x200000>;
> +            operating-points-v2 = <&mcc_opp>;
> +            apple,num-channels = <8>;
> +        };
> +
> +        clk_pcluster: clock-controller@...e20000 {
> +            compatible = "apple,t8103-cluster-clk", "apple,cluster-clk";
> +            #clock-cells = <0>;
> +            reg = <0x2 0x11e20000 0x0 0x4000>;
> +            operating-points-v2 = <&pcluster_opp>;
> +            power-domains = <&mcc>;
> +        };
> +    };
> 


Best regards,
Krzysztof