linux-kernel - [PATCH v2 1/4] dt-bindings: cpufreq: Add mediatek,mt8196-cpufreq-hw binding

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Message-Id: <20250714-mt8196-cpufreq-v2-1-cc85e78855c7@collabora.com>
Date: Mon, 14 Jul 2025 16:08:14 +0200
From: Nicolas Frattaroli <nicolas.frattaroli@...labora.com>
To: "Rafael J. Wysocki" <rafael@...nel.org>, 
 Viresh Kumar <viresh.kumar@...aro.org>, Rob Herring <robh@...nel.org>, 
 Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, 
 Matthias Brugger <matthias.bgg@...il.com>, 
 AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
Cc: kernel@...labora.com, linux-pm@...r.kernel.org, 
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-arm-kernel@...ts.infradead.org, linux-mediatek@...ts.infradead.org, 
 Nicolas Frattaroli <nicolas.frattaroli@...labora.com>
Subject: [PATCH v2 1/4] dt-bindings: cpufreq: Add
 mediatek,mt8196-cpufreq-hw binding

The MediaTek MT8196 SoC has new cpufreq hardware, with added memory
register ranges to control Dynamic-Voltage-Frequency-Scaling.

The DVFS hardware is controlled through a set of registers referred to
as "FDVFS"; one is a location from which a magic number is read to
ensure DVFS should be used, the other is a region to set the desired
target frequency that DVFS should aim towards for each performance
domain.

Instead of working around the old binding and its already established
meanings for the reg items, add a new binding. The FDVFS register memory
regions are at the beginning, which allows us to easily expand this
binding for future SoCs which may have more than 3 performance domains.

Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@...labora.com>
---
 .../cpufreq/mediatek,mt8196-cpufreq-hw.yaml        | 86 ++++++++++++++++++++++
 1 file changed, 86 insertions(+)

diff --git a/Documentation/devicetree/bindings/cpufreq/mediatek,mt8196-cpufreq-hw.yaml b/Documentation/devicetree/bindings/cpufreq/mediatek,mt8196-cpufreq-hw.yaml
new file mode 100644
index 0000000000000000000000000000000000000000..26bf21e05888646b4d1bdac95bfba0f36e037ffd
--- /dev/null
+++ b/Documentation/devicetree/bindings/cpufreq/mediatek,mt8196-cpufreq-hw.yaml
@@ -0,0 +1,86 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/cpufreq/mediatek,mt8196-cpufreq-hw.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: MediaTek CPUFreq for MT8196 and related SoCs
+
+maintainers:
+  - Nicolas Frattaroli <nicolas.frattaroli@...labora.com>
+
+description:
+  MT8196 uses CPUFreq management hardware that supports dynamic voltage
+  frequency scaling (dvfs), and can support several performance domains.
+
+properties:
+  compatible:
+    const: mediatek,mt8196-cpufreq-hw
+
+  reg:
+    items:
+      - description: FDVFS magic number register region
+      - description: FDVFS control register region
+      - description: OPP tables and control for performance domain 0
+      - description: OPP tables and control for performance domain 1
+      - description: OPP tables and control for performance domain 2
+
+  "#performance-domain-cells":
+    description:
+      Number of cells in a performance domain specifier. Must be 1.
+    const: 1
+
+required:
+  - compatible
+  - reg
+  - "#performance-domain-cells"
+
+additionalProperties: false
+
+examples:
+  - |
+    cpus {
+            #address-cells = <1>;
+            #size-cells = <0>;
+
+            cpu0: cpu@0 {
+                device_type = "cpu";
+                compatible = "arm,cortex-a720";
+                enable-method = "psci";
+                performance-domains = <&performance 0>;
+                reg = <0x000>;
+            };
+
+            /* ... */
+
+            cpu6: cpu@600 {
+                device_type = "cpu";
+                compatible = "arm,cortex-x4";
+                enable-method = "psci";
+                performance-domains = <&performance 1>;
+                reg = <0x600>;
+            };
+
+            cpu7: cpu@700 {
+                device_type = "cpu";
+                compatible = "arm,cortex-x925";
+                enable-method = "psci";
+                performance-domains = <&performance 2>;
+                reg = <0x700>;
+            };
+    };
+
+    /* ... */
+
+    soc {
+        #address-cells = <2>;
+        #size-cells = <2>;
+
+        performance: performance-controller@...2034 {
+            compatible = "mediatek,mt8196-cpufreq-hw";
+            reg = <0 0xc2c2034 0 0x4>, <0 0xc220400 0 0x20>,
+                  <0 0xc2c0f20 0 0x120>, <0 0xc2c1040 0 0x120>,
+                  <0 0xc2c1160 0 0x120>;
+            #performance-domain-cells = <1>;
+        };
+    };

-- 
2.50.1