diff --git a/raspberry-pi/4/apply-overlays-dtmerge.nix b/raspberry-pi/4/apply-overlays-dtmerge.nix
new file mode 100644
index 0000000..0d17bb8
--- /dev/null
+++ b/raspberry-pi/4/apply-overlays-dtmerge.nix
@@ -0,0 +1,30 @@
+{ lib, pkgs, stdenvNoCC, dtc, libraspberrypi }:
+
+with lib; {
+  applyOverlays = (base: overlays': stdenvNoCC.mkDerivation {
+    name = "device-tree-overlays";
+    nativeBuildInputs = [ dtc ];
+    buildCommand = let
+      overlays = toList overlays';
+    in ''
+      mkdir -p $out
+      cd ${base}
+      find . -type f -name '*.dtb' -print0 \
+        | xargs -0 cp -v --no-preserve=mode --target-directory $out --parents
+      for dtb in $(find $out -type f -name '*.dtb'); do
+        dtbCompat="$( fdtget -t s $dtb / compatible )"
+        ${flip (concatMapStringsSep "\n") overlays (o: ''
+        overlayCompat="$( fdtget -t s ${o.dtboFile} / compatible )"
+        # overlayCompat in dtbCompat
+        if [[ "$dtbCompat" =~ "$overlayCompat" ]]; then
+          echo "Applying overlay ${o.name} to $( basename $dtb )"
+          mv $dtb{,.in}
+          cp ${o.dtboFile}{,.dtbo}
+          ${libraspberrypi}/bin/dtmerge "$dtb.in" "$dtb" ${o.dtboFile}.dtbo;
+          rm $dtb.in ${o.dtboFile}.dtbo
+        fi
+        '')}
+      done
+    '';
+  });
+}
diff --git a/raspberry-pi/4/default.nix b/raspberry-pi/4/default.nix
index fcaf5ad..d85063a 100644
--- a/raspberry-pi/4/default.nix
+++ b/raspberry-pi/4/default.nix
@@ -7,8 +7,10 @@
     ./i2c.nix
     ./modesetting.nix
     ./poe-hat.nix
+    ./poe-plus-hat.nix
     ./tc358743.nix
     ./pwm0.nix
+    ./pkgs-overlays.nix
   ];
 
   boot = {
diff --git a/raspberry-pi/4/pkgs-overlays.nix b/raspberry-pi/4/pkgs-overlays.nix
new file mode 100644
index 0000000..4b3c16d
--- /dev/null
+++ b/raspberry-pi/4/pkgs-overlays.nix
@@ -0,0 +1,22 @@
+{ config, lib, pkgs, modulesPath, ... }:
+let
+  callPackage = path: overrides:
+    let f = import path;
+    in f ((builtins.intersectAttrs (builtins.functionArgs f) pkgs) // overrides);
+  cfg = config.hardware.raspberry-pi."4".apply-overlays-dtmerge;
+  dt_ao_overlay = (final: prev: {
+    deviceTree.applyOverlays = (prev.callPackage ./apply-overlays-dtmerge.nix { }).applyOverlays;
+  });
+in {
+  options.hardware = {
+    raspberry-pi."4".apply-overlays-dtmerge = {
+      enable = lib.mkEnableOption ''
+        replace deviceTree.applyOverlays implementation to use dtmerge from libraspberrypi.
+      '';
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    nixpkgs.overlays = [ dt_ao_overlay ];
+  };
+}
diff --git a/raspberry-pi/4/poe-hat.nix b/raspberry-pi/4/poe-hat.nix
index ea19129..bda9925 100644
--- a/raspberry-pi/4/poe-hat.nix
+++ b/raspberry-pi/4/poe-hat.nix
@@ -1,6 +1,6 @@
 { config, lib, pkgs, ... }:
 
-let 
+let
   cfg = config.hardware.raspberry-pi."4".poe-hat;
 in {
   options.hardware = {
@@ -12,10 +12,11 @@ in {
   };
 
   config = lib.mkIf cfg.enable {
-    # Configure for modesetting in the device tree
+    hardware.raspberry-pi."4".apply-overlays-dtmerge.enable = lib.mkDefault true;
+
     hardware.deviceTree = {
       overlays = [
-        # Equivalent to: https://github.com/raspberrypi/linux/blob/rpi-5.10.y/arch/arm/boot/dts/overlays/rpi-poe-overlay.dts
+        # Equivalent to: https://github.com/raspberrypi/linux/blob/rpi-5.15.y/arch/arm/boot/dts/overlays/rpi-poe-overlay.dts
         {
           name = "rpi-poe-overlay";
           dtsText = ''
@@ -31,14 +32,11 @@ in {
               fragment@0 {
                 target-path = "/";
                 __overlay__ {
-                  fan0: rpi-poe-fan@0 {
-                    compatible = "raspberrypi,rpi-poe-fan";
-                    firmware = <&firmware>;
-                    cooling-min-state = <0>;
-                    cooling-max-state = <4>;
-                    #cooling-cells = <2>;
+                  fan: pwm-fan {
+                    compatible = "pwm-fan";
                     cooling-levels = <0 1 10 100 255>;
-                    status = "okay";
+                    #cooling-cells = <2>;
+                    pwms = <&fwpwm 0 80000>;
                   };
                 };
               };
@@ -71,19 +69,19 @@ in {
                   cooling-maps {
                     map0 {
                       trip = <&trip0>;
-                      cooling-device = <&fan0 0 1>;
+                      cooling-device = <&fan 0 1>;
                     };
                     map1 {
                       trip = <&trip1>;
-                      cooling-device = <&fan0 1 2>;
+                      cooling-device = <&fan 1 2>;
                     };
                     map2 {
                       trip = <&trip2>;
-                      cooling-device = <&fan0 2 3>;
+                      cooling-device = <&fan 2 3>;
                     };
                     map3 {
                       trip = <&trip3>;
-                      cooling-device = <&fan0 3 4>;
+                      cooling-device = <&fan 3 4>;
                     };
                   };
                 };
@@ -91,7 +89,7 @@ in {
 
               fragment@2 {
                 target-path = "/__overrides__";
-                __overlay__ {
+                params: __overlay__ {
                   poe_fan_temp0 =		<&trip0>,"temperature:0";
                   poe_fan_temp0_hyst =	<&trip0>,"hysteresis:0";
                   poe_fan_temp1 =		<&trip1>,"temperature:0";
@@ -100,6 +98,54 @@ in {
                   poe_fan_temp2_hyst =	<&trip2>,"hysteresis:0";
                   poe_fan_temp3 =		<&trip3>,"temperature:0";
                   poe_fan_temp3_hyst =	<&trip3>,"hysteresis:0";
+                  poe_fan_i2c =		<&fwpwm>,"status=disabled",
+                        <&poe_mfd>,"status=okay",
+                        <&fan>,"pwms:0=",<&poe_mfd_pwm>;
+                };
+              };
+
+              fragment@3 {
+                target = <&firmware>;
+                __overlay__ {
+                  fwpwm: pwm {
+                    compatible = "raspberrypi,firmware-poe-pwm";
+                    #pwm-cells = <2>;
+                  };
+                };
+              };
+
+              fragment@4 {
+                target = <&i2c0>;
+                i2c_bus: __overlay__ {
+                  #address-cells = <1>;
+                  #size-cells = <0>;
+
+                  poe_mfd: poe@51 {
+                    compatible = "raspberrypi,poe-core";
+                    reg = <0x51>;
+                    status = "disabled";
+
+                    poe_mfd_pwm: poe_pwm@f0 {
+                      compatible = "raspberrypi,poe-pwm";
+                      reg = <0xf0>;
+                      status = "okay";
+                      #pwm-cells = <2>;
+                    };
+                  };
+                };
+              };
+
+              fragment@5 {
+                target = <&i2c0if>;
+                __dormant__ {
+                  status = "okay";
+                };
+              };
+
+              fragment@6 {
+                target = <&i2c0mux>;
+                __dormant__ {
+                  status = "okay";
                 };
               };
 
@@ -112,6 +158,11 @@ in {
                 poe_fan_temp2_hyst =	<&trip2>,"hysteresis:0";
                 poe_fan_temp3 =		<&trip3>,"temperature:0";
                 poe_fan_temp3_hyst =	<&trip3>,"hysteresis:0";
+                i2c =			<0>, "+5+6",
+                      <&fwpwm>,"status=disabled",
+                      <&i2c_bus>,"status=okay",
+                      <&poe_mfd>,"status=okay",
+                      <&fan>,"pwms:0=",<&poe_mfd_pwm>;
               };
             };
           '';
diff --git a/raspberry-pi/4/poe-plus-hat.nix b/raspberry-pi/4/poe-plus-hat.nix
new file mode 100644
index 0000000..79177fe
--- /dev/null
+++ b/raspberry-pi/4/poe-plus-hat.nix
@@ -0,0 +1,223 @@
+{ config, lib, pkgs, ... }:
+
+let 
+  cfg = config.hardware.raspberry-pi."4".poe-plus-hat;
+in {
+  options.hardware = {
+    raspberry-pi."4".poe-plus-hat = {
+      enable = lib.mkEnableOption ''
+        support for the Raspberry Pi PoE+ HAT.
+      '';
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    hardware.raspberry-pi."4".apply-overlays-dtmerge.enable = lib.mkDefault true;
+
+    hardware.deviceTree = {
+      overlays = [
+        # Combined equivalent to:
+        # * https://github.com/raspberrypi/linux/blob/rpi-5.15.y/arch/arm/boot/dts/overlays/rpi-poe-overlay.dts
+        # * https://github.com/raspberrypi/linux/blob/rpi-5.15.y/arch/arm/boot/dts/overlays/rpi-poe-plus-overlay.dts
+        {
+          name = "rpi-poe-plus-overlay";
+          dtsText = ''
+            /*
+            * Overlay for the Raspberry Pi POE HAT.
+            */
+            /dts-v1/;
+            /plugin/;
+
+            / {
+              compatible = "brcm,bcm2711";
+
+              fragment@0 {
+                target-path = "/";
+                __overlay__ {
+                  fan: pwm-fan {
+                    compatible = "pwm-fan";
+                    cooling-levels = <0 1 10 100 255>;
+                    #cooling-cells = <2>;
+                    pwms = <&fwpwm 0 80000>;
+                  };
+                };
+              };
+
+              fragment@1 {
+                target = <&cpu_thermal>;
+                __overlay__ {
+                  trips {
+                    trip0: trip0 {
+                      temperature = <40000>;
+                      hysteresis = <2000>;
+                      type = "active";
+                    };
+                    trip1: trip1 {
+                      temperature = <45000>;
+                      hysteresis = <2000>;
+                      type = "active";
+                    };
+                    trip2: trip2 {
+                      temperature = <50000>;
+                      hysteresis = <2000>;
+                      type = "active";
+                    };
+                    trip3: trip3 {
+                      temperature = <55000>;
+                      hysteresis = <5000>;
+                      type = "active";
+                    };
+                  };
+                  cooling-maps {
+                    map0 {
+                      trip = <&trip0>;
+                      cooling-device = <&fan 0 1>;
+                    };
+                    map1 {
+                      trip = <&trip1>;
+                      cooling-device = <&fan 1 2>;
+                    };
+                    map2 {
+                      trip = <&trip2>;
+                      cooling-device = <&fan 2 3>;
+                    };
+                    map3 {
+                      trip = <&trip3>;
+                      cooling-device = <&fan 3 4>;
+                    };
+                  };
+                };
+              };
+
+              fragment@2 {
+                target-path = "/__overrides__";
+                params: __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";
+                  poe_fan_temp2 =		<&trip2>,"temperature:0";
+                  poe_fan_temp2_hyst =	<&trip2>,"hysteresis:0";
+                  poe_fan_temp3 =		<&trip3>,"temperature:0";
+                  poe_fan_temp3_hyst =	<&trip3>,"hysteresis:0";
+                  poe_fan_i2c =		<&fwpwm>,"status=disabled",
+                        <&poe_mfd>,"status=okay",
+                        <&fan>,"pwms:0=",<&poe_mfd_pwm>;
+                };
+              };
+
+              fragment@3 {
+                target = <&firmware>;
+                __overlay__ {
+                  fwpwm: pwm {
+                    compatible = "raspberrypi,firmware-poe-pwm";
+                    #pwm-cells = <2>;
+                  };
+                };
+              };
+
+              fragment@4 {
+                target = <&i2c0>;
+                i2c_bus: __overlay__ {
+                  #address-cells = <1>;
+                  #size-cells = <0>;
+
+                  poe_mfd: poe@51 {
+                    compatible = "raspberrypi,poe-core";
+                    reg = <0x51>;
+                    status = "disabled";
+
+                    poe_mfd_pwm: poe_pwm@f0 {
+                      compatible = "raspberrypi,poe-pwm";
+                      reg = <0xf0>;
+                      status = "okay";
+                      #pwm-cells = <2>;
+                    };
+                  };
+                };
+              };
+
+              fragment@5 {
+                target = <&i2c0if>;
+                __dormant__ {
+                  status = "okay";
+                };
+              };
+
+              fragment@6 {
+                target = <&i2c0mux>;
+                __dormant__ {
+                  status = "okay";
+                };
+              };
+
+              __overrides__ {
+                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";
+                poe_fan_temp2 =		<&trip2>,"temperature:0";
+                poe_fan_temp2_hyst =	<&trip2>,"hysteresis:0";
+                poe_fan_temp3 =		<&trip3>,"temperature:0";
+                poe_fan_temp3_hyst =	<&trip3>,"hysteresis:0";
+                i2c =			<0>, "+5+6",
+                      <&fwpwm>,"status=disabled",
+                      <&i2c_bus>,"status=okay",
+                      <&poe_mfd>,"status=okay",
+                      <&fan>,"pwms:0=",<&poe_mfd_pwm>;
+              };
+            };
+
+            // SPDX-License-Identifier: (GPL-2.0 OR MIT)
+            // Overlay for the Raspberry Pi PoE+ HAT.
+
+            / {
+                compatible = "brcm,bcm2711";
+
+                fragment@10 {
+                    target-path = "/";
+                    __overlay__ {
+                        rpi_poe_power_supply: rpi-poe-power-supply {
+                            compatible = "raspberrypi,rpi-poe-power-supply";
+                            firmware = <&firmware>;
+                            status = "okay";
+                        };
+                    };
+                };
+                fragment@11 {
+                    target = <&poe_mfd>;
+                    __overlay__ {
+                        rpi-poe-power-supply@f2 {
+                            compatible = "raspberrypi,rpi-poe-power-supply";
+                            reg = <0xf2>;
+                            status = "okay";
+                        };
+                    };
+                };
+
+                __overrides__ {
+                    i2c =	<0>, "+5+6",
+                        <&fwpwm>,"status=disabled",
+                        <&rpi_poe_power_supply>,"status=disabled",
+                        <&i2c_bus>,"status=okay",
+                        <&poe_mfd>,"status=okay",
+                        <&fan>,"pwms:0=",<&poe_mfd_pwm>;
+                };
+            };
+
+            &fan {
+                cooling-levels = <0 32 64 128 255>;
+            };
+
+            &params {
+                poe_fan_i2c = <&fwpwm>,"status=disabled",
+                        <&rpi_poe_power_supply>,"status=disabled",
+                        <&poe_mfd>,"status=okay",
+                        <&fan>,"pwms:0=",<&poe_mfd_pwm>;
+            };
+          '';
+        }
+      ];
+    };
+  };
+}