Add fix for IPMI fan speed

Author: AgenttiX

drivers/fix_ipmi_fans.sh

@@ -0,0 +1,30 @@
+#!/usr/bin/env bash
+set -eu
+
+# Fix for fans ramping up and down on Supermicro server motherboards.
+# https://www.truenas.com/community/threads/fans-ramping-up-and-down-and-fan-mode-option-not-visible-in-ipmi-supermicro-x9scm-f.70826/
+# https://www.truenas.com/community/resources/how-to-change-ipmi-sensor-thresholds-using-ipmitool.35/
+
+if [ "${EUID}" -ne 0 ]; then
+  echo "This script should be run as root."
+  exit 1
+fi
+
+SENSORS=$(ipmitool sensor list all)
+FANS=$(grep '^FAN' <<< "${SENSORS}")
+
+while IFS= read -r LINE; do
+  NAME="${LINE%% *}"
+  echo "Configuring ${NAME}"
+  # The three numbers are lnr, lcr, lnc
+  # nr = non-recoverable
+  # cr = critical
+  # nc = non-critical
+  # My home server has Noctua NF-A12x25 PWM fans, which are rated for 450 - 2000 RPM.
+  # https://www.amazon.de/-/en/gp/product/B07C5VG64V/
+  # And Arctic Freezer 4U SP3, which is rated for 400 - 2300 RPM.
+  # https://www.arctic.de/en/Freezer-4U-SP3/ACFRE00081A
+  # These values will be rounded by the motherboard to 140, 140 and ???.
+  ipmitool sensor thresh "${NAME}" lower 100 200 450
+  # ipmitool sensor thresh "${NAME}" upper
+done <<< "${FANS}"