#!/bin/bash

# You can change these values to suit.
TEMPERATURE_MAX=90
THROTTLED_CLOCK=1000000

# You can limit the top speed to less than the default maximum by setting
# MAX_CLOCK to the clock speed in KHz.
MAX_CLOCK=`cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies | sed -e 's/.* \([0-9]* $\)/\1/'`

# We set the speed to MAX_CLOCK, just in case it is lower than the actual
# maximum
echo $MAX_CLOCK > /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq
echo $MAX_CLOCK > /sys/devices/system/cpu/cpu1/cpufreq/scaling_max_freq

while [ 1 ]; do
	current_max_clock=`cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq`
	temperature=`sensors | grep temp2 | sed -e 's/temp2: *+//' -e 's/°.*//' -e 's/\.[0-9]//'`

	# Uncomment the following two lines for extra debug verbosity
	# echo "Current temperature: $temperature"
	# echo "Current maximum clock: $current_max_clock"

	# if temperature exceeds the throttling threshold...
	if [ $temperature -gt $TEMPERATURE_MAX ]; then
		# ... and if we aren't already throttled ...
		if [ $current_max_clock -gt $THROTTLED_CLOCK ]; then
			# ... reduce scaling_max_freq to $THROTTLED_CLOCK
			echo "CPU temperature exceeds $TEMPERATURE_MAX C. Reducing speed to $THROTTLED_CLOCK KHz"
			echo $THROTTLED_CLOCK > /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq
			echo $THROTTLED_CLOCK > /sys/devices/system/cpu/cpu1/cpufreq/scaling_max_freq
			sleep 2
		fi
	# if temperature is below the throttling threshold ...
	else
		# ... and if we aren't at $MAX_CLOCK already ...
		if [ $current_max_clock -lt $MAX_CLOCK ]; then
			# Unthrottle
			echo "CPU temperature below $TEMPERATURE_MAX C. Boosting speed to $MAX_CLOCK KHz"
			echo $MAX_CLOCK > /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq
			echo $MAX_CLOCK > /sys/devices/system/cpu/cpu1/cpufreq/scaling_max_freq
		fi
	fi
	sleep 1
done