amdgpu: add custom fan control

hosts/monolith/amdgpu.nix

@@ -1,4 +1,4 @@
-{ pkgs, ... }:
+{ pkgs, lib, ... }:
 let
   undervoltGpu = pkgs.writeShellScript "undervolt-gpu" ''
     set -xe
@@ -18,6 +18,13 @@ in
     "amdgpu.ppfeaturemask=0xfffd7fff" # enable undervolting
   ];
 
+  systemd.services.amd-fan-control = {
+    script = ''
+      ${lib.getExe pkgs.amd-fan-control} /sys/class/drm/card1/device 60 85
+    '';
+    wantedBy = [ "multi-user.target" ];
+  };
+
   hardware.opengl.driSupport = true;
   # # For 32 bit applications
   hardware.opengl.driSupport32Bit = true;

scripts/amd-fan-control

@@ -0,0 +1,50 @@
+#!/usr/bin/env bash
+
+set -e
+
+DEVICE="$1" # eg: /sys/class/drm/card1/device
+HWMON=$(echo "$DEVICE"/hwmon/hwmon*)
+
+exit() {
+    echo "Setting controll to auto" >&2
+    echo 2 > "$HWMON/pwm1_enable"
+}
+
+trap exit EXIT INT
+
+bail() {
+    echo "Error: $@" >&2
+    echo "Exiting..." >&2
+    exit 1
+}
+
+if ! [ -d $HWMON ]; then
+    bail "Invalid HWMON"
+fi
+
+TEMP_INPUT="$HWMON/temp2_input"
+
+if ! [ -f $TEMP_INPUT ]; then
+    bail "Invalid TEMP_INPUT"
+fi
+
+MIN="$2"
+MAX="$3"
+
+echo "Running..." >&2
+while true; do
+    TEMPERATURE_RAW=$(cat "$TEMP_INPUT")
+    TEMPERATURE="$(( $TEMPERATURE_RAW / 1000 ))"
+    # Remap from a number between 60_000..90_000 to 0..255
+    PWM=$(( ($TEMPERATURE - $MIN) * 255 / ($MAX - $MIN) ))
+
+    if [ "$PWM" -gt 255 ]; then
+        PWM=255
+    elif [ "$PWM" -lt 0 ]; then
+        PWM=0
+    fi
+
+    echo 1 > "$HWMON/pwm1_enable"
+    echo "$PWM" > "$HWMON/pwm1"
+    sleep .1s
+done

scripts/default.nix

@@ -23,6 +23,7 @@
   in
   with final;
   createScripts {
+    amd-fan-control = [ bash ];
     br = [ ];
     bmenu = [
       bemenu