dt-bindings: thermal: add binding documentation for UniPhier thermal monitor

Add devicetree binding documentation for thermal monitor implemented on
Socionext UniPhier SoCs.
Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>

Documentation/devicetree/bindings/thermal/uniphier-thermal.txt

+* UniPhier Thermal bindings
+
+This describes the devicetree bindings for thermal monitor supported by
+PVT(Process, Voltage and Temperature) monitoring unit implemented on Socionext
+UniPhier SoCs.
+
+Required properties:
+- compatible :
+  - "socionext,uniphier-pxs2-thermal" : For UniPhier PXs2 SoC
+  - "socionext,uniphier-ld20-thermal" : For UniPhier LD20 SoC
+- interrupts : IRQ for the temperature alarm
+- #thermal-sensor-cells : Should be 0. See ./thermal.txt for details.
+
+Optional properties:
+- socionext,tmod-calibration: A pair of calibrated values referred from PVT,
+                              in case that the values aren't set on SoC,
+                              like a reference board.
+
+Example:
+
+	sysctrl@61840000 {
+		compatible = "socionext,uniphier-ld20-sysctrl",
+			     "simple-mfd", "syscon";
+		reg = <0x61840000 0x10000>;
+		...
+		pvtctl: pvtctl {
+			compatible = "socionext,uniphier-ld20-thermal";
+			interrupts = <0 3 1>;
+			#thermal-sensor-cells = <0>;
+		};
+		...
+	};
+
+	thermal-zones {
+		cpu_thermal {
+			polling-delay-passive = <250>;	/* 250ms */
+			polling-delay = <1000>;		/* 1000ms */
+			thermal-sensors = <&pvtctl>;
+
+			trips {
+				cpu_crit: cpu_crit {
+					temperature = <110000>;	/* 110C */
+					hysteresis = <2000>;
+					type = "critical";
+				};
+				cpu_alert: cpu_alert {
+					temperature = <100000>;	/* 100C */
+					hysteresis = <2000>;
+					type = "passive";
+				};
+			};
+
+			cooling-maps {
+				map0 {
+					trip = <&cpu_alert>;
+					cooling-device = <&cpu0 (-1) (-1)>;
+				};
+				map1 {
+					trip = <&cpu_alert>;
+					cooling-device = <&cpu2 (-1) (-1)>;
+				};
+			};
+		};
+	};