#!/bin/bash
#
# Script implementing a temperature dependent fan speed control.
#
# Usage: fancontrol [CONFIGFILE]
#
# Version 1.0
#
# Dependencies:
#   * awk (for the math expression evaluation)
#   * lm_sensors :)
#   * A correctly configured config file, default /etc/fancontrol, see pwmconfig
#     for creating an initial version.
#
# For configuration instructions and warnings please see fancontrol.txt, which
# can be found in the lm_sensors package.
#
#   Copyright 2003 Marius Reiner <marius.reiner@hdev.de>
#   http://www.hdev.de/fancontrol/  up to version 0.63
#
#   Copyright 2006 Volker Kuhlmann <VolkerKuhlmann@gmx.de>
#   http://volker.dnsalias.net/  from version 1.0
#
#   Changelog:
#   1.0, 24 Jan 2006:
#     * Tidied up script, replacing sub-optimal shell constructs.
#     * Added hysteresis when turning fan on/off, preventing the fan from going
#       between off and minimum every $INTERVAL seconds.
#       This change is upwards compatible; the script's behaviour is unchanged
#       with older config files.
#       TODO: add hysteresis handling to pwmconfig
#     * Fixed the sleep constructs to be usable with system service scripts.
#     * Rudimentary provision for multiple (different) control curves
#   0.63, 2003:
#     * by Marius Reiner
#
#   This program is free software; you can redistribute it and/or modify
#   it under the terms of the GNU General Public License as published by
#   the Free Software Foundation; either version 2 of the License, or
#   (at your option) any later version.
#
#   This program is distributed in the hope that it will be useful,
#   but WITHOUT ANY WARRANTY; without even the implied warranty of
#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#   GNU General Public License for more details.
#
#   You should have received a copy of the GNU General Public License
#   along with this program; if not, write to the Free Software
#   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
#

#DEBUG=1
MAX=255
PIDFILE=/var/run/fancontrol.pid
SENSDIR=/proc/sys/dev/sensors
SSENSDIR=/sys/bus/i2c/devices


# $1: config file to load
function LoadConfig {
    echo "Loading configuration from $1 ..."
    while read -r; do
	case "$REPLY" in
	    INTERVAL=*)   INTERVAL="${REPLY#*=}";;
	    FCTEMPS=*)    FCTEMPS="${REPLY#*=}";;
	    MINTEMP=*)    MINTEMP="${REPLY#*=}";;
	    MAXTEMP=*)    MAXTEMP="${REPLY#*=}";;
	    MINSTART=*)   MINSTART="${REPLY#*=}";;
	    MINSTOP=*)    MINSTOP="${REPLY#*=}";;
	    # optional settings:
	    FCFANS=*)     FCFANS="${REPLY#*=}";;
	    THRESHTEMP=*) THRTEMP="${REPLY#*=}";;
	esac
    done < "$1"

    # Check whether all mandatory settings are set
    if [[ -z ${INTERVAL} || -z ${FCTEMPS} || -z ${MINTEMP} || -z ${MAXTEMP} || -z ${MINSTART} || -z ${MINSTOP} ]]
    then
	echo "Some mandatory settings missing, please check your config file!"
	exit 1
    fi
    # here the other settings should be verified


    # write settings to arrays for easier use and print them
    getpwmval() {
	local pwm
	for pwm in $1; do
	    case "$pwm" in
		*$2=*)   echo "${pwm#*=}"; break;;
	    esac
	done
    }
    echo
    echo "Common settings:"
    echo "  INTERVAL=$INTERVAL"
    let fcvcount=0
    for fcv in $FCTEMPS; do
	AFCPWM[$fcvcount]="${fcv%%=*}"  # field 1
	AFCTEMP[$fcvcount]="${fcv#*=}"  # field 2
	AFCFAN[$fcvcount]=`getpwmval "$FCFANS" "${AFCPWM[$fcvcount]}"`
	AFCMINTEMP[$fcvcount]=`getpwmval "$MINTEMP" "${AFCPWM[$fcvcount]}"`
	AFCMAXTEMP[$fcvcount]=`getpwmval "$MAXTEMP" "${AFCPWM[$fcvcount]}"`
	AFCTHRTEMP[$fcvcount]=`getpwmval "$THRTEMP" "${AFCPWM[$fcvcount]}"`
	AFCMINSTART[$fcvcount]=`getpwmval "$MINSTART" "${AFCPWM[$fcvcount]}"`
	AFCMINSTOP[$fcvcount]=`getpwmval "$MINSTOP" "${AFCPWM[$fcvcount]}"`
	# Default threshold:
	test -z "${AFCTHRTEMP[$fcvcount]}" && AFCTHRTEMP[$fcvcount]=0
	echo
	echo "Settings for ${AFCPWM[$fcvcount]}:"
	echo "  Depends on ${AFCTEMP[$fcvcount]}"
	echo "  Controls ${AFCFAN[$fcvcount]}"
	echo "  MINTEMP=${AFCMINTEMP[$fcvcount]}"
	echo "  MAXTEMP=${AFCMAXTEMP[$fcvcount]}"
	echo "  THRTEMP=${AFCTHRTEMP[$fcvcount]}"
	echo "  MINSTART=${AFCMINSTART[$fcvcount]}"
	echo "  MINSTOP=${AFCMINSTOP[$fcvcount]}"
	let fcvcount=fcvcount+1
    done
    echo
}

# $1 = full pwm file name
function pwmdisable()
{
    if [ "$SYSFS" = "1" ]; then
	echo $MAX > $1
	ENABLE=${1}_enable
	if [ -f $ENABLE ]; then
	    echo 0 > $ENABLE
	fi
    else
	echo $MAX 0 > $1
    fi
}

# $1 = full pwm file name
function pwmenable()
{
    if [ "$SYSFS" = "1" ]; then
	ENABLE=${1}_enable
	if [ -f $ENABLE ]; then
	    echo 1 > $ENABLE
	fi
    else
	echo $MAX 1 > $1
    fi
}

# Set fans to maximum and exit.
function restorefans()
{
    echo "Aborting, restoring fans..."
    let fcvcount=0
    while (( $fcvcount < ${#AFCPWM[@]} )); do # go through all pwm outputs
	pwmo=${AFCPWM[$fcvcount]}
	pwmdisable $SENSDIR/$pwmo
	let fcvcount=$fcvcount+1
    done
    echo 'Verify fans have returned to full speed'
    rm "$PIDFILE"
    exit 0
}

# Function evaluating the mathematical expression.
function calc () {
    awk "BEGIN { print $@ }"
    # Alternatives: bc, or bc -l
}

# Calculate the new value from temperature and settings; quadratic function.
# Sets variables pwmval and func!
calc_quadratic() {
    func="((${tval}-${mint})/(${maxt}-${mint}))^2*(255-${minso})+${minso}"
    pwmval=`calc "$func"`
    pwmval="${pwmval%%.*}"
}

# Calculate the new value from temperature and settings; "quad" function?
# Sets variables pwmval and func!
calc_quad() {
    func="((10/(${maxt}-${mint})*(${temp}-${mint}))^2/1000*(${maxt}-${mint})*(255-${minspeed})+${minspeed})"
    pwmval=`calc "$func"`
    pwmval="${pwmval%%.*}"
}

# Calculate the new value from temperature and settings; exponential function.
# Sets variables pwmval and func!
calc_exponential() {
    func="..."
    pwmval=`calc "$func"`
    pwmval="${pwmval%%.*}"
}

# main function
function UpdateFanSpeeds {
    local filler filler2
    let fcvcount=0
    while (( $fcvcount < ${#AFCPWM[@]} )); do # go through all pwm outputs
	#hopefully shorter vars will improve readability:
	pwmo=${AFCPWM[$fcvcount]}
	tsens=${AFCTEMP[$fcvcount]}
	fan=${AFCFAN[$fcvcount]}
	mint=${AFCMINTEMP[$fcvcount]}
	maxt=${AFCMAXTEMP[$fcvcount]}
	minsa=${AFCMINSTART[$fcvcount]}
	minso=${AFCMINSTOP[$fcvcount]}
	thresht=${AFCTHRTEMP[$fcvcount]}

	read tval < $SENSDIR/${tsens} || {
	    echo "Error reading temperature from $SENSDIR/$tsens"
	    restorefans
	}
	if [ "$SYSFS" = "1" ]; then
	    let tval="$tval / 1000"
	else
	    tval=`echo ${tval} |cut -d' ' -f3 |cut -d'.' -f1`
	fi

	read pwmpval filler < $SENSDIR/${pwmo} || {
	    echo "Error reading PWM value from $SENSDIR/$pwmo"
	    restorefans
	}

	# If fanspeed-sensor output shall be used, do it
	if [[ -n ${fan} ]]; then
	    read filler fanval filler2 < $SENSDIR/${fan} || {
		echo "Error reading Fan value from $SENSDIR/$fan"
		restorefans
	    }
	    test "$fanval" || fanval=$filler  # field 2, or first field
	else
	    fanval=1  # set it to a non zero value, so the rest of the script still works
	fi

	# debug info
	if [ -n "$DEBUG" ]; then
	    echo ""
	    echo "pwmo=$pwmo"
	    echo "tsens=$tsens"
	    echo "fan=$fan"
	    echo "mint=$mint"
	    echo "maxt=$maxt"
	    echo "thresht=$thresht"
	    echo "minsa=$minsa"
	    echo "minso=$minso"
	    echo "tval=$tval"
	    echo "pwmpval=$pwmpval"
	    echo "fanval=$fanval"
	fi

    	if (( $tval <= $mint ))
	    then pwmval=0 # at specified mintemp shut fan off
	elif (( $tval >= $maxt ))
	    then pwmval=255 # at specified maxtemp switch to 100%
	else
	    # Calculate the new value from temperature and settings.
	    # (Sets variables pwmval and func.)
	    calc_quadratic
	    
	    # If fan was stopped, start it using a safe value,
	    # but only start it if temp is at least the threshold over minimum.
	    if [ $pwmpval -eq 0 -o $fanval -eq 0 ]; then
		if (( $tval >= (( $mint + $thresht )) )); then
		    if [ -n "$DEBUG" ]; then
			echo "starting fan with pwmval=$minsa"
		    fi
		    echo $minsa > $SENSDIR/$pwmo
		    # ignore possible error
		    #sleep 1  # not killable
		    read < <(exec sleep 1)
		else
		    pwmval=0
		fi
	    fi
	fi

	# write new value to pwm output
	echo $pwmval > $SENSDIR/$pwmo || {
	    echo "Error writing PWM value to $SENSDIR/$pwmo"
	    restorefans
	}
	if [ -n "$DEBUG" ]; then
    	    echo "func=$func"
	    echo "new pwmval=$pwmval"
	fi
	let fcvcount=$fcvcount+1
    done
}


## MAIN

LoadConfig "${1-/etc/fancontrol}"

if [ -e "$PIDFILE" ]; then
    echo 1>&2 "$0: Error: PID file already exists: $PIDFILE"
    exit 1
fi

if [ ! -d $SENSDIR ]; then
    if [ ! -d $SSENSDIR ]; then
	echo $0: 'No sensors found! (did you load the necessary modules?)'
	exit 1
    else
	SYSFS=1
	SENSDIR=$SSENSDIR
    fi	
fi
# cd $SENSDIR   # Let's not stand in procfs or sysfs!

trap restorefans SIGHUP SIGINT SIGQUIT SIGTERM SIGKILL

echo $$ > "$PIDFILE"

echo 'Enabling PWM on fans...'
let fcvcount=0
while (( $fcvcount < ${#AFCPWM[@]} )); do # go through all pwm outputs
    pwmo=${AFCPWM[$fcvcount]}
    pwmenable $SENSDIR/$pwmo
    if [ $? -ne 0 ]; then
	echo "Error enabling PWM on $SENSDIR/$pwmo"
	restorefans
    fi
    let fcvcount=$fcvcount+1
done

echo 'Starting automatic fan control...'
# main loop calling the main function at specified intervals
while true; do
    UpdateFanSpeeds
    # The sleep in the foreground isn't interruptible by kill, which is
    # unsuitable for system service scripts.
    # Werner@suse doesn't like  sleep $INTERVAL &; wait $! although it works.
    read < <(exec sleep $INTERVAL)
done