From cf3508aab6123ad958b6aa6e766cb65c572ad41d Mon Sep 17 00:00:00 2001
From: James Walker <walkah@walkah.net>
Date: Wed, 2 Jun 2021 20:47:23 -0400
Subject: [PATCH] raspberry-pi/4: Add poe-hat option

---
 raspberry-pi/4/default.nix |   1 +
 raspberry-pi/4/poe-hat.nix | 122 +++++++++++++++++++++++++++++++++++++
 2 files changed, 123 insertions(+)
 create mode 100644 raspberry-pi/4/poe-hat.nix

diff --git a/raspberry-pi/4/default.nix b/raspberry-pi/4/default.nix
index d9f5f9b..3699190 100644
--- a/raspberry-pi/4/default.nix
+++ b/raspberry-pi/4/default.nix
@@ -4,6 +4,7 @@
   imports = [
     ./dwc2.nix
     ./modesetting.nix
+    ./poe-hat.nix
     ./tc358743.nix
   ];
 
diff --git a/raspberry-pi/4/poe-hat.nix b/raspberry-pi/4/poe-hat.nix
new file mode 100644
index 0000000..a7ef673
--- /dev/null
+++ b/raspberry-pi/4/poe-hat.nix
@@ -0,0 +1,122 @@
+{ config, lib, pkgs, ... }:
+
+let 
+  cfg = config.hardware.raspberry-pi."4".poe-hat;
+in {
+  options.hardware = {
+    raspberry-pi."4".poe-hat = {
+      enable = lib.mkEnableOption ''
+        Enable support for the Raspberry Pi POE Hat.
+      '';
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    # Configure for modesetting in the device tree
+    hardware.deviceTree = {
+      overlays = [
+        # Equivalent to: https://github.com/raspberrypi/linux/blob/rpi-5.10.y/arch/arm/boot/dts/overlays/rpi-poe-overlay.dts
+        {
+          name = "rpi-poe-overlay";
+          dtsText = ''
+            /*
+            * Overlay for the Raspberry Pi POE HAT.
+            */
+            /dts-v1/;
+            /plugin/;
+
+            / {
+              compatible = "brcm,bcm2711";
+
+              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>;
+                    cooling-levels = <0 1 10 100 255>;
+                    status = "okay";
+                  };
+                };
+              };
+
+              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 = <&fan0 0 1>;
+                    };
+                    map1 {
+                      trip = <&trip1>;
+                      cooling-device = <&fan0 1 2>;
+                    };
+                    map2 {
+                      trip = <&trip2>;
+                      cooling-device = <&fan0 2 3>;
+                    };
+                    map3 {
+                      trip = <&trip3>;
+                      cooling-device = <&fan0 3 4>;
+                    };
+                  };
+                };
+              };
+
+              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";
+                  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";
+                };
+              };
+
+              __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";
+              };
+            };
+          '';
+        }
+      ];
+    };
+  };
+}