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

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Message-Id: <20211011165707.138157-4-marcan@marcan.st>
Date:   Tue, 12 Oct 2021 01:57:01 +0900
From:   Hector Martin <marcan@...can.st>
To:     linux-arm-kernel@...ts.infradead.org
Cc:     Hector Martin <marcan@...can.st>,
        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>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
        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: [RFC PATCH 3/9] dt-bindings: clock: Add apple,cluster-clk binding

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
+
+
+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";
+
+        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>;
+        };
+    };
-- 
2.33.0