ARM: tegra: paz00: Add CPU thermal zone

Add thermal zone with a passive cooling trip for CPU. Attach it to the
LM90 sensor which monitors CPU temperature. Now CPU frequencies will be
throttled once trip point is reached, preventing critical overheat.
Tested-by: Agneli <poczt@protonmail.ch>
Tested-by: Paul Fertser <fercerpav@gmail.com>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

arch/arm/boot/dts/tegra20-paz00.dts

@@ -2,6 +2,8 @@
 /dts-v1/;
 
 #include <dt-bindings/input/input.h>
+#include <dt-bindings/thermal/thermal.h>
+
 #include "tegra20.dtsi"
 #include "tegra20-cpu-opp.dtsi"
 #include "tegra20-cpu-opp-microvolt.dtsi"
@@ -498,9 +500,10 @@ ldo_rtc {
 			};
 		};
 
-		adt7461@4c {
+		adt7461: temperature-sensor@4c {
 			compatible = "adi,adt7461";
 			reg = <0x4c>;
+			#thermal-sensor-cells = <1>;
 		};
 	};
 
@@ -655,11 +658,46 @@ cpus {
 		cpu0: cpu@0 {
 			cpu-supply = <&cpu_vdd_reg>;
 			operating-points-v2 = <&cpu0_opp_table>;
+			#cooling-cells = <2>;
 		};
 
-		cpu@1 {
+		cpu1: cpu@1 {
 			cpu-supply = <&cpu_vdd_reg>;
 			operating-points-v2 = <&cpu0_opp_table>;
+			#cooling-cells = <2>;
+		};
+	};
+
+	thermal-zones {
+		cpu-thermal {
+			polling-delay-passive = <500>; /* milliseconds */
+			polling-delay = <1500>; /* milliseconds */
+
+			thermal-sensors = <&adt7461 1>;
+
+			trips {
+				trip0: cpu-alert0 {
+					/* start throttling at 80C */
+					temperature = <80000>;
+					hysteresis = <200>;
+					type = "passive";
+				};
+
+				trip1: cpu-crit {
+					/* shut down at 85C */
+					temperature = <85000>;
+					hysteresis = <2000>;
+					type = "critical";
+				};
+			};
+
+			cooling-maps {
+				map0 {
+					trip = <&trip0>;
+					cooling-device = <&cpu0 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
+							 <&cpu1 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>;
+				};
+			};
 		};
 	};
 };