Re: [PATCH v3 2/5] dt-bindings: cpufreq: apple,soc-cpufreq: Add binding for Apple SoC cpufreq

From: Krzysztof Kozlowski
Date: Tue Oct 25 2022 - 12:01:52 EST


On 24/10/2022 00:39, Hector Martin wrote:
> This binding represents the cpufreq/DVFS hardware present in Apple SoCs.
> The hardware has an independent controller per CPU cluster, and we
> represent them as unique nodes in order to accurately describe the
> hardware. The driver is responsible for binding them as a single cpufreq
> device (in the Linux cpufreq model).
>
> Signed-off-by: Hector Martin <marcan@xxxxxxxxx>
> ---
> .../cpufreq/apple,cluster-cpufreq.yaml | 119 ++++++++++++++++++
> 1 file changed, 119 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/cpufreq/apple,cluster-cpufreq.yaml
>
> diff --git a/Documentation/devicetree/bindings/cpufreq/apple,cluster-cpufreq.yaml b/Documentation/devicetree/bindings/cpufreq/apple,cluster-cpufreq.yaml
> new file mode 100644
> index 000000000000..b11452f91468
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/cpufreq/apple,cluster-cpufreq.yaml
> @@ -0,0 +1,119 @@
> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/cpufreq/apple,cluster-cpufreq.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Apple SoC cluster cpufreq device

Few nits, in general looks fine to me.

> +
> +maintainers:
> + - Hector Martin <marcan@xxxxxxxxx>
> +
> +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:
> + oneOf:
> + - items:
> + - const: apple,t8103-cluster-cpufreq
> + - const: apple,cluster-cpufreq
> + - items:
> + - const: apple,t6000-cluster-cpufreq
> + - const: apple,t8103-cluster-cpufreq
> + - const: apple,cluster-cpufreq
> + - items:
> + - const: apple,t8112-cluster-cpufreq

With the first one (t8103) - it's an enum.

> + - const: apple,cluster-cpufreq
> +
> + reg:
> + maxItems: 1
> + description: The register region for this CPU cluster DVFS controller

Drop description, quite obvious.

> +
> + '#performance-domain-cells':
> + const: 0
> +
> +required:
> + - compatible
> + - reg
> + - '#performance-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>;
> + performance-domains = <&cpufreq_e>;
> + };
> +
> + cpu@10100 {
> + compatible = "apple,firestorm";
> + device_type = "cpu";
> + reg = <0x0 0x10100>;
> + operating-points-v2 = <&pcluster_opp>;
> + performance-domains = <&cpufreq_p>;
> + };
> + };
> +
> + 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_e: cpufreq@210e20000 {

Node name: performance-controller

(cpufreq is rather Linux naming)

> + compatible = "apple,t8103-cluster-cpufreq", "apple,cluster-cpufreq";
> + reg = <0x2 0x10e20000 0 0x1000>;
> + #performance-domain-cells = <0>;
> + };
> +
> + cpufreq_p: cpufreq@211e20000 {

The same.

> + compatible = "apple,t8103-cluster-cpufreq", "apple,cluster-cpufreq";
> + reg = <0x2 0x11e20000 0 0x1000>;
> + #performance-domain-cells = <0>;
> + };
> + };

Best regards,
Krzysztof