of: Add bindings of hw throttle for Tegra soctherm

Add HW throttle configuration sub-node for soctherm, which
is used to describe the throttle event, and worked as a
cooling device. The "hot" type trip in thermal zone can
be bound to this cooling device, and trigger the throttle
function.

Signed-off-by: Wei Ni <[e-mail]>
Acked-by: Rob Herring <[e-mail]>
Signed-off-by: Zhang Rui <[e-mail]>

Documentation/devicetree/bindings/thermal/nvidia,tegra124-soctherm.txt

···
 - compatible : For Tegra124, must contain "nvidia,tegra124-soctherm".
   For Tegra132, must contain "nvidia,tegra132-soctherm".
   For Tegra210, must contain "nvidia,tegra210-soctherm".
-- reg : Should contain 1 entry:
+- reg : Should contain at least 2 entries for each entry in reg-names:
   - SOCTHERM register set
+  - Tegra CAR register set: Required for Tegra124 and Tegra210.
+  - CCROC register set: Required for Tegra132.
+- reg-names :  Should contain at least 2 entries:
+  - soctherm-reg
+  - car-reg
+  - ccroc-reg
 - interrupts : Defines the interrupt used by SOCTHERM
 - clocks : Must contain an entry for each entry in clock-names.
   See ../clocks/clock-bindings.txt for details.
···
 - #thermal-sensor-cells : Should be 1. See ./thermal.txt for a description
     of this property. See <dt-bindings/thermal/tegra124-soctherm.h> for a
     list of valid values when referring to thermal sensors.
+- throttle-cfgs: A sub-node which is a container of configuration for each
+    hardware throttle events. These events can be set as cooling devices.
+  * throttle events: Sub-nodes must be named as "light" or "heavy".
+      Properties:
+      - nvidia,priority: Each throttles has its own throttle settings, so the
+        SW need to set priorities for various throttle, the HW arbiter can select
+        the final throttle settings.
+        Bigger value indicates higher priority, In general, higher priority
+        translates to lower target frequency. SW needs to ensure that critical
+        thermal alarms are given higher priority, and ensure that there is
+        no race if priority of two vectors is set to the same value.
+        The range of this value is 1~100.
+      - nvidia,cpu-throt-percent: This property is for Tegra124 and Tegra210.
+        It is the throttling depth of pulse skippers, it's the percentage
+        throttling.
+      - nvidia,cpu-throt-level: This property is only for Tegra132, it is the
+        level of pulse skippers, which used to throttle clock frequencies. It
+        indicates cpu clock throttling depth, and the depth can be programmed.
+        Must set as following values:
+        TEGRA_SOCTHERM_THROT_LEVEL_LOW, TEGRA_SOCTHERM_THROT_LEVEL_MED
+        TEGRA_SOCTHERM_THROT_LEVEL_HIGH, TEGRA_SOCTHERM_THROT_LEVEL_NONE
+      - #cooling-cells: Should be 1. This cooling device only support on/off state.
+        See ./thermal.txt for a description of this property.
 
 Note:
 - the "critical" type trip points will be set to SOC_THERM hardware as the
 shut down temperature. Once the temperature of this thermal zone is higher
 than it, the system will be shutdown or reset by hardware.
+- the "hot" type trip points will be set to SOC_THERM hardware as the throttle
+temperature. Once the the temperature of this thermal zone is higher
+than it, it will trigger the HW throttle event.
 
 Example :
 
 	soctherm@700e2000 {
 		compatible = "nvidia,tegra124-soctherm";
-		reg = <0x0 0x700e2000 0x0 0x1000>;
+		reg = <0x0 0x700e2000 0x0 0x600  /* SOC_THERM reg_base */
+			0x0 0x60006000 0x0 0x400 /* CAR reg_base */
+		reg-names = "soctherm-reg", "car-reg";
 		interrupts = <GIC_SPI 48 IRQ_TYPE_LEVEL_HIGH>;
 		clocks = <&tegra_car TEGRA124_CLK_TSENSOR>,
 			<&tegra_car TEGRA124_CLK_SOC_THERM>;
···
 		reset-names = "soctherm";
 
 		#thermal-sensor-cells = <1>;
+
+		throttle-cfgs {
+			/*
+			 * When the "heavy" cooling device triggered,
+			 * the HW will skip cpu clock's pulse in 85% depth
+			 */
+			throttle_heavy: heavy {
+				nvidia,priority = <100>;
+				nvidia,cpu-throt-percent = <85>;
+
+				#cooling-cells = <1>;
+			};
+
+			/*
+			 * When the "light" cooling device triggered,
+			 * the HW will skip cpu clock's pulse in 50% depth
+			 */
+			throttle_light: light {
+				nvidia,priority = <80>;
+				nvidia,cpu-throt-percent = <50>;
+
+				#cooling-cells = <1>;
+			};
+
+			/*
+			 * If these two devices are triggered in same time, the HW throttle
+			 * arbiter will select the highest priority as the final throttle
+			 * settings to skip cpu pulse.
+			 */
+		};
+	};
+
+Example: referring to Tegra132's "reg", "reg-names" and "throttle-cfgs" :
+
+	soctherm@700e2000 {
+		compatible = "nvidia,tegra132-soctherm";
+		reg = <0x0 0x700e2000 0x0 0x600  /* SOC_THERM reg_base */
+			0x0 0x70040000 0x0 0x200>; /* CCROC reg_base */;
+		reg-names = "soctherm-reg", "ccroc-reg";
+
+		throttle-cfgs {
+			/*
+			 * When the "heavy" cooling device triggered,
+			 * the HW will skip cpu clock's pulse in HIGH level
+			 */
+			throttle_heavy: heavy {
+				nvidia,priority = <100>;
+				nvidia,cpu-throt-level = <TEGRA_SOCTHERM_THROT_LEVEL_HIGH>;
+
+				#cooling-cells = <1>;
+			};
+
+			/*
+			 * When the "light" cooling device triggered,
+			 * the HW will skip cpu clock's pulse in MED level
+			 */
+			throttle_light: light {
+				nvidia,priority = <80>;
+				nvidia,cpu-throt-level = <TEGRA_SOCTHERM_THROT_LEVEL_MED>;
+
+				#cooling-cells = <1>;
+			};
+
+			/*
+			 * If these two devices are triggered in same time, the HW throttle
+			 * arbiter will select the highest priority as the final throttle
+			 * settings to skip cpu pulse.
+			 */
+
+		};
 	};
 
 Example: referring to thermal sensors :
···
 					temperature = <102500>;
 					hysteresis = <1000>;
 					type = "critical";
+				};
+
+				cpu_throttle_trip: throttle-trip {
+					temperature = <100000>;
+					hysteresis = <1000>;
+					type = "hot";
+				};
+			};
+
+			cooling-maps {
+				map0 {
+					trip = <&cpu_throttle_trip>;
+					cooling-device = <&throttle_heavy 1 1>;
 				};
 			};
                 };