overlays: add overrides for PoE HAT fan control

Signed-off-by: Serge Schneider <[email protected]>

Author: XECDesign

arch/arm/boot/dts/overlays/README

@@ -1596,9 +1596,16 @@ Params: touchscreen-size-x      Touchscreen X resolution (default 800)
 
 
 Name:   rpi-poe
-Info:   Raspberry Pi POE HAT
-Load:   dtoverlay=rpi-poe
-Params: <None>
+Info:   Raspberry Pi PoE HAT fan
+Load:   dtoverlay=rpi-poe,<param>[=<val>]
+Params: poe_fan_temp0           Temperature (in millicelcius) at which the fan
+                                turns on (default 50000)
+        poe_fan_temp0_hyst      Temperature delta (in millicelcius) at which
+                                the fan turns off (default 5000)
+        poe_fan_temp1           Temperature (in millicelcius) at which the fan
+                                speeds up (default 55000)
+        poe_fan_temp1_hyst      Temperature delta (in millicelcius) at which
+                                the fan slows down (default 5000)
 
 
 Name:   rpi-proto

arch/arm/boot/dts/overlays/rpi-poe-overlay.dts

@@ -50,4 +50,14 @@
 			};
 		};
 	};
+
+	fragment@2 {
+		target-path = "/__overrides__";
+		__overlay__ {
+			poe_fan_temp0 =		<&trip0>,"temperature:0";
+			poe_fan_temp0_hyst =	<&trip0>,"hysteresis:0";
+			poe_fan_temp1 =		<&trip1>,"temperature:0";
+			poe_fan_temp1_hyst =	<&trip1>,"hysteresis:0";
+		};
+	};
 };