x220 power management init script

#!/bin/sh
### BEGIN INIT INFO
# Provides: x220-pm
# Required-Start:    $local_fs
# Required-Stop:     $local_fs
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: Sets various power management features for X220 laptops
# Description:       Sets available power management options in /sys for X220 laptops.
#                    Disables PCI "Runtime PM" on shutdown in order to shutdown the
#                    laptop properly.
### END INIT INFO

set -e

BAT_START_CHARGE_THRESH=30
BAT_STOP_CHARGE_THRESH=85
PCI_RUNTIME_PM_ACTIVE='auto'
PCI_RUNTIME_PM_DISABLED='on'
SATA_LINK_PM_POLICY='min_power'
CPU_GOVERNOR='ondemand'


various_pm() {
# disables WOL for ethernet device
# enables WLAN device power management
# enables sound card power management
    ethtool -s eth0 wol d
    ifconfig eth0 down
    iwconfig wlan0 power on
    echo 1 > /sys/module/snd_hda_intel/parameters/power_save
}

bat_charge_thresh() {
# sets battery charge thresholds
# note: start_charge_thresh doesn't work with smapi 0.41 and is therefore disabled
    local start_thresh=$1
    local stop_thresh=$2
    for bat in /sys/devices/platform/smapi/BAT*
    do
        #echo $start_thresh > $bat/start_charge_thresh
        echo $stop_thresh > $bat/stop_charge_thresh
    done
}

sata_link_pm() {
# sets SATA link power management policy
    local policy=$1
    for linkpm in /sys/class/scsi_host/host*/link_power_management_policy
    do
        echo $policy > $linkpm
    done
}

cpu_governor() {
# sets the CPU scaling governor
    local gov=$1
    for cpugov in /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor
    do
        echo $gov > $cpugov
    done
}

pci_runtime_pm() {
# sets the PCI runtime PM for all available devices
    local mode=$1 # 'on' or 'auto' where 'auto' is causing shutdown problems
    for pcicontrol in /sys/bus/pci/devices/*/power/control
    do
        echo $mode > $pcicontrol
    done
}


case "$1" in
    start)
        various_pm
        bat_charge_thresh $BAT_START_CHARGE_THRESH $BAT_STOP_CHARGE_THRESH
        cpu_governor $CPU_GOVERNOR
        sata_link_pm $SATA_LINK_PM_POLICY
        pci_runtime_pm $PCI_RUNTIME_PM_ACTIVE
    ;;
    stop)
        pci_runtime_pm $PCI_RUNTIME_PM_DISABLED
    ;;
    *)
        N=/etc/init.d/x220-pm
        echo "Usage: $N {start|stop}" >&2
        exit 1
    ;;
esac

exit 0