Re: [PATCH v5 2/4] dt-bindings: cpufreq: apple,soc-cpufreq: Add binding for Apple SoC cpufreq
From: Ulf Hansson <hidden>
Date: 2022-11-29 11:37:36
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asahi, linux-devicetree, linux-pm, lkml
On Mon, 28 Nov 2022 at 15:29, Hector Martin [off-list ref] wrote:
quoted hunk ↗ jump to hunk
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). Acked-by: Marc Zyngier <maz@kernel.org> Signed-off-by: Hector Martin <redacted> --- .../cpufreq/apple,cluster-cpufreq.yaml | 117 ++++++++++++++++++ 1 file changed, 117 insertions(+) create mode 100644 Documentation/devicetree/bindings/cpufreq/apple,cluster-cpufreq.yamldiff --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..76cb9726660e --- /dev/null +++ b/Documentation/devicetree/bindings/cpufreq/apple,cluster-cpufreq.yaml@@ -0,0 +1,117 @@ +# 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 + +maintainers: + - Hector Martin <marcan@marcan.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: + oneOf: + - items: + - enum: + - apple,t8103-cluster-cpufreq + - apple,t8112-cluster-cpufreq + - const: apple,cluster-cpufreq + - items: + - const: apple,t6000-cluster-cpufreq + - const: apple,t8103-cluster-cpufreq + - const: apple,cluster-cpufreq + + reg: + maxItems: 1 + + '#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>;
To me, it looks like the operating-points-v2 phandle better belongs in the performance-domains provider node. I mean, isn't the OPPs really a description of the performance-domain provider? That said, I suggest we try to extend the generic performance-domain binding [1] with an "operating-points-v2". In that way, we should instead be able to reference it from this binding. In fact, that would be very similar to what already exists for the generic power-domain binding [2]. I think it would be rather nice to follow a similar pattern for the performance-domain binding.
+ 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: performance-controller@210e20000 {
+ compatible = "apple,t8103-cluster-cpufreq", "apple,cluster-cpufreq";
+ reg = <0x2 0x10e20000 0 0x1000>;
+ #performance-domain-cells = <0>;
+ };
+
+ cpufreq_p: performance-controller@211e20000 {
+ compatible = "apple,t8103-cluster-cpufreq", "apple,cluster-cpufreq";
+ reg = <0x2 0x11e20000 0 0x1000>;
+ #performance-domain-cells = <0>;
+ };
+ };Kind regards Uffe [1] Documentation/devicetree/bindings/dvfs/performance-domain.yaml [2] Documentation/devicetree/bindings/power/power-domain.yaml _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel