#!/bin/bash

# Automatic fan controller
# Tested on a eee 1005ha running Ubuntu 9.10 Karmic Koala

# Test with 'sudo eeefan background'.
# If works, 'sudo cp eeefan /etc/rc2.d/S99eeefan'
# and reboot.

temperature_reading=/sys/devices/virtual/thermal/thermal_zone0/temp
fan_control=/sys/devices/platform/eeepc/hwmon/hwmon1/pwm1
fan_manual_switch=/sys/devices/platform/eeepc/hwmon/hwmon1/pwm1_enable

# Set critical temperature
TEMP_CRITICAL=57
FAN_SPEED_CRITICAL=250

# Set critical temperature interval size. See figure for details
TEMP_INTERVAL_SIZE=5

# Maximum fan speed
FAN_SPEED_MAX=125

eeefanupdate() {
  
    # Get temperature reading
    TEMP=$(cat $temperature_reading)
    TEMP=$(($TEMP / 1000)) 

  if [  $TEMP -le $TEMP_CRITICAL ]; then
  {
    # Calculate optimum fan speed
    X=$(echo "$FAN_SPEED_MAX*1/(1+e(-($TEMP-$TEMP_CRITICAL)/$TEMP_INTERVAL_SIZE))" | bc -q -l)
    # Workaround to convert it to nearest integer
    FAN_SPEED=$(echo "scale=0; $X/1.0" | bc -q -l)
    # Set fan speed
    FAN_SPEED=$(($FAN_SPEED * 250 / 100)) 
    echo $FAN_SPEED > $fan_control
 
  }
  else 
  {
    echo $FAN_SPEED_CRITICAL > $fan_control
    echo $FAN_SPEED_CRITICAL
  }
  fi

}

        # Turn on manual fan control
        echo 1 > $fan_manual_switch

        # Run eeefanu, then wait 10 seconds.

        while [ 1 ]
        do
            eeefanupdate
                sleep 10
        
        done

sudo ./eeefan

sudo cp eeefan /etc/rc2.d/S99eeefan

sudo pwmconfig