[PATCH 2/2] arm64: dts: marvell: Enable AP806 thermal throttling with CPUfreq

[Miquel Raynal <miquel.raynal@bootlin.com>]

Avoid critical temperatures in the AP806 by adding the relevant trip
points/cooling-maps using CPUfreq as cooling device.

So far, when the temperature reaches 100°C in the thermal IP of the
AP806 (close enough from the 2/4 cores) an overheat interrupt is
raised. The thermal core then shutdowns the system to avoid damaging
the hardware.

Adding CPUfreq as a cooling device could help avoiding such very
critical situation. For that, we enable thermal throttling by
defining, for each CPU, two trip points with the corresponding cooling
'intensity'. CPU0 and CPU1 are in the same cluster and are driven by
the same clock. Same applies for CPU2 and CPU3, if available. So
changing the frequency of one will also change the frequency of the
other one, hence the use of two cooling devices per core.

The heat map is as follow:
- Below 85°C: the cluster runs at the highest frequency
  (e.g: 1200MHz).
- Between 85°C and 95°C: there are two trip points at half
  (e.g: 600MHz) and a third (e.g: 400MHz) of the highest frequency.
- Above 95°C the cluster runs at a quarter of the highest frequency
  (e.g: 300MHz).
- At 100°C the platform is shutdown.

Suggested-by: Omri Itach <omrii@marvell.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 .../boot/dts/marvell/armada-ap806-dual.dtsi   |   2 +
 .../boot/dts/marvell/armada-ap806-quad.dtsi   |   5 +
 arch/arm64/boot/dts/marvell/armada-ap806.dtsi | 102 ++++++++++++++++--
 3 files changed, 99 insertions(+), 10 deletions(-)

diff --git a/arch/arm64/boot/dts/marvell/armada-ap806-dual.dtsi b/arch/arm64/boot/dts/marvell/armada-ap806-dual.dtsi
index d3c0636558ff..8883ff46dff6 100644
--- a/arch/arm64/boot/dts/marvell/armada-ap806-dual.dtsi
+++ b/arch/arm64/boot/dts/marvell/armada-ap806-dual.dtsi
@@ -20,12 +20,14 @@
 			compatible = "arm,cortex-a72", "arm,armv8";
 			reg = <0x000>;
 			enable-method = "psci";
+			#cooling-cells = <2>;
 		};
 		cpu1: cpu@1 {
 			device_type = "cpu";
 			compatible = "arm,cortex-a72", "arm,armv8";
 			reg = <0x001>;
 			enable-method = "psci";
+			#cooling-cells = <2>;
 		};
 	};
 };
diff --git a/arch/arm64/boot/dts/marvell/armada-ap806-quad.dtsi b/arch/arm64/boot/dts/marvell/armada-ap806-quad.dtsi
index c2c81d4e2d38..31e12d04a2cd 100644
--- a/arch/arm64/boot/dts/marvell/armada-ap806-quad.dtsi
+++ b/arch/arm64/boot/dts/marvell/armada-ap806-quad.dtsi
@@ -21,6 +21,7 @@
 			reg = <0x000>;
 			enable-method = "psci";
 			clocks = <&cpu_clk 0>;
+			#cooling-cells = <2>;
 		};
 		cpu1: cpu@1 {
 			device_type = "cpu";
@@ -28,6 +29,7 @@
 			reg = <0x001>;
 			enable-method = "psci";
 			clocks = <&cpu_clk 0>;
+			#cooling-cells = <2>;
 		};
 		cpu2: cpu@100 {
 			device_type = "cpu";
@@ -35,6 +37,7 @@
 			reg = <0x100>;
 			enable-method = "psci";
 			clocks = <&cpu_clk 1>;
+			#cooling-cells = <2>;
 		};
 		cpu3: cpu@101 {
 			device_type = "cpu";
@@ -42,6 +45,8 @@
 			reg = <0x101>;
 			enable-method = "psci";
 			clocks = <&cpu_clk 1>;
+			#cooling-cells = <2>;
 		};
 	};
+
 };
diff --git a/arch/arm64/boot/dts/marvell/armada-ap806.dtsi b/arch/arm64/boot/dts/marvell/armada-ap806.dtsi
index 1029ff7d7c49..fc125f5ea6d6 100644
--- a/arch/arm64/boot/dts/marvell/armada-ap806.dtsi
+++ b/arch/arm64/boot/dts/marvell/armada-ap806.dtsi
@@ -286,8 +286,6 @@
 	 *
 	 * Only one thermal zone per AP/CP may trigger interrupts at a time, the
 	 * first one that will have a critical trip point will be chosen.
-	 *
-	 * The cooling maps are always empty as there are no cooling devices.
 	 */
 	thermal-zones {
 		ap_thermal_ic: ap-thermal-ic {
@@ -313,8 +311,29 @@
 
 			thermal-sensors = <&ap_thermal 1>;
 
-			trips { };
-			cooling-maps { };
+			trips {
+				cpu0_hot: cpu0-hot {
+					temperature = <85000>;
+					hysteresis = <2000>;
+					type = "passive";
+				};
+				cpu0_emerg: cpu0-emerg {
+					temperature = <95000>;
+					hysteresis = <2000>;
+					type = "passive";
+				};
+			};
+
+			cooling-maps {
+				map0_hot: map0-hot {
+					trip = <&cpu0_hot>;
+					cooling-device = <&cpu0 1 2>, <&cpu1 1 2>;
+				};
+				map0_emerg: map0-ermerg {
+					trip = <&cpu0_emerg>;
+					cooling-device = <&cpu0 3 3>, <&cpu1 3 3>;
+				};
+			};
 		};
 
 		ap_thermal_cpu1: ap-thermal-cpu1 {
@@ -323,8 +342,29 @@
 
 			thermal-sensors = <&ap_thermal 2>;
 
-			trips { };
-			cooling-maps { };
+			trips {
+				cpu1_hot: cpu1-hot {
+					temperature = <85000>;
+					hysteresis = <2000>;
+					type = "passive";
+				};
+				cpu1_emerg: cpu1-emerg {
+					temperature = <95000>;
+					hysteresis = <2000>;
+					type = "passive";
+				};
+			};
+
+			cooling-maps {
+				map1_hot: map1-hot {
+					trip = <&cpu1_hot>;
+					cooling-device = <&cpu0 1 2>, <&cpu1 1 2>;
+				};
+				map1_emerg: map1-emerg {
+					trip = <&cpu1_emerg>;
+					cooling-device = <&cpu0 3 3>, <&cpu1 3 3>;
+				};
+			};
 		};
 
 		ap_thermal_cpu2: ap-thermal-cpu2 {
@@ -333,8 +373,29 @@
 
 			thermal-sensors = <&ap_thermal 3>;
 
-			trips { };
-			cooling-maps { };
+			trips {
+				cpu2_hot: cpu2-hot {
+					temperature = <85000>;
+					hysteresis = <2000>;
+					type = "passive";
+				};
+				cpu2_emerg: cpu2-emerg {
+					temperature = <95000>;
+					hysteresis = <2000>;
+					type = "passive";
+				};
+			};
+
+			cooling-maps {
+				map2_hot: map2-hot {
+					trip = <&cpu2_hot>;
+					cooling-device = <&cpu2 1 2>, <&cpu3 1 2>;
+				};
+				map2_emerg: map2-emerg {
+					trip = <&cpu2_emerg>;
+					cooling-device = <&cpu2 3 3>, <&cpu3 3 3>;
+				};
+			};
 		};
 
 		ap_thermal_cpu3: ap-thermal-cpu3 {
@@ -343,8 +404,29 @@
 
 			thermal-sensors = <&ap_thermal 4>;
 
-			trips { };
-			cooling-maps { };
+			trips {
+				cpu3_hot: cpu3-hot {
+					temperature = <85000>;
+					hysteresis = <2000>;
+					type = "passive";
+				};
+				cpu3_emerg: cpu3-emerg {
+					temperature = <95000>;
+					hysteresis = <2000>;
+					type = "passive";
+				};
+			};
+
+			cooling-maps {
+				map3_hot: map3-bhot {
+					trip = <&cpu3_hot>;
+					cooling-device = <&cpu2 1 2>, <&cpu3 1 2>;
+				};
+				map3_emerg: map3-emerg {
+					trip = <&cpu3_emerg>;
+					cooling-device = <&cpu2 3 3>, <&cpu3 3 3>;
+				};
+			};
 		};
 	};
 };
-- 
2.19.1


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