#!/bin/bash

# Fan speed control / low-battery autosuspend script for Thinkpad
# T410, by teknohog

# requires:

# thinkpad-acpi module with the option fan_control=1
# awk (was: bc, but awk should be universally available)
# acpitool

# A wider range makes the curve flatter == more stable; Currently I am
# maxing out around 56 C (undervolted), so it should never actually go near
# 80 C.

# 2016-05-13 see new format below
MAXTEMP=78000
MINTEMP=48000

# The mapping from the fan level (0 to 7) to the actual
# speed/noise/cooling effect is horribly nonlinear and ill-defined. I
# think a stepwise function could be much better, but it would take a
# little more work...

# suspend when battery level is below this percentage
AUTOSUSP_BAT=2

# cycle time in seconds
WAIT=5

#THERMALFILE=/proc/acpi/ibm/thermal

# 2016-05-13 this also works for X220i, with somewhat different format
THERMALFILE=/sys/devices/virtual/thermal/thermal_zone0/temp

FANFILE=/proc/acpi/ibm/fan

MAXFAN=7
MINFAN=0

# Something like this can be used to find the actual maximum, but it
# might not be safe/general enough
#MAXFAN=$(cat $FANFILE | grep commands | grep level | sed -E 's/.* 0-([0-9]+).*/\1/')

# 2016-05-27 passive cooling devices. One should be enough, choose
# from something like Processor or intel_powerclamp. Use a higher
# minimum temperature to avoid triggering this in normal use.
# 2016-05-30 intel_powerclamp seems slightly more effective, so use it
# if available

for PASS_TYPE in intel_powerclamp Processor; do
    PASS_DIR=$(for FILE in /sys/class/thermal/cooling_device*/type; do if [ $(cat $FILE) == "$PASS_TYPE" ]; then dirname $FILE; break; fi; done)
    if [ -d "$PASS_DIR" ]; then break; fi
done
       
if [ ! -d "$PASS_DIR" ]; then
    echo No passive cooling device found, exiting.
    exit
fi

PASS_FILE=$PASS_DIR/cur_state
PASS_MAX=$(cat $PASS_DIR/max_state)
PASS_MIN=0
PASS_MINTEMP=72000

# Now needed more generally. Proper rounding: round(x) = int(x + 0.5)
# since int = floor or ceil(x) = int(x + 0.999999) almost everywhere
lin_adjust() {
    # input order: $TEMP $MINTEMP $MAXTEMP $MINLEVEL $MAXLEVEL
    echo $@ | awk '{level = ($1-$2)/($3-$2)*($5-$4) + $4
if (level > $5) level = $5
if (level < $4) level = $4
print int(level + 0.999999)}'
}

safequit () {
    setfan auto
    exit
}

fancontrol () {
    TEMP=$(cat $THERMALFILE)

    # This should be made more general for multiple coolers, but keep
    # it simple and light
    lin_adjust $TEMP $PASS_MINTEMP $MAXTEMP $PASS_MIN $PASS_MAX > $PASS_FILE

    # Also, the "level $LEVEL" setting complicates this a bit
    FANLEVEL=$(lin_adjust $TEMP $MINTEMP $MAXTEMP $MINFAN $MAXFAN)
    echo level $FANLEVEL > $FANFILE
}

autosuspend () {
    # we need to read 2 things from one command, better call it only once
    ACPI=`acpitool`

    #BAT=`readbattery`

    BAT=`echo $ACPI | sed -e 's/.* \([0-9]\{1,3\}\.[0-9]\{1,2\}\)%.*/\1/'`
    # round downwards to be on the safe side
    BAT=${BAT//\.*/}

    # Low battery is OK if we are on-line
    if [ $BAT -le $AUTOSUSP_BAT ] && [ -z "`echo $ACPI | egrep on-?line`" ]; then
	/root/bin/suspend.sh
    fi
}

# don't run multiple instances; if one is running already, two's a crowd
#SCRIPT=`basename $0`
#if [ "`pgrep $SCRIPT | wc -l`" -gt 2 ]; then exit; fi

NRUN=$(ps ax | grep $(basename $0) | egrep -v "grep|basename" | wc -l)
if [ $NRUN -gt 2 ]; then exit; fi

trap 'safequit' TERM

# main loop, different functions should be factored out
while true; do 
    fancontrol

    autosuspend
    
    sleep $WAIT
done