#!/bin/bash
#set -x

VID=6993
PIDS="b001 b700"
DRIVER="yealink"
IFCLASS="03"     # hexadecimal: 03..HID

if uname -r | grep -q '^2\.6\.28\>' ; then
  echo "WARNING: Your kernel version may suffer from kernel bug #12301, which"
  echo "prevents using the device after unbinding it! The bug is due to be"
  echo "fixed in kernel version 2.6.29."
  echo
fi

function attach() {
  local id dr
  id="$1"
  dr="$2"
  [ -f /sys/bus/usb/drivers/$dr/bind ] && \
    echo -n "$d" > /sys/bus/usb/drivers/$dr/bind
  if [ $? = 0 ]
  then
    echo "  successfully reattached driver '$dr'"
  else
    echo "  could not reattach device to driver '$dr'"
  fi
}

find /sys/devices -name idVendor | \
  while read v
  do
    if [ "`cat $v`" = "$VID" ]
    then
      base="${v%/*}"
      pid="`cat $base/idProduct`"
      #if "$pid" = "$PID"    # use this for just one PID
      if echo $PIDS | grep -q "\\<$pid\\>"
      then
        cd "$base"
        devname=`cat product | sed 's/ *$//'`
        echo "Found device '$devname' at $base"
        find . -name bInterfaceClass | \
          while read c
          do
            if [ "`cat $c`" = "$IFCLASS" ]
            then
              # this is the interface we are looking for
              d="${c%/*}"
              cd "$d"
              d="`pwd`"
              d="${d##*/}"
              echo "  found interface at $d"
              if [ -e "driver/unbind" ]
              then
                drvr=`readlink driver`
                drvr=${drvr##*/}
                if [ "$drvr" = "$DRIVER" ]
                then
                  echo "  driver '$DRIVER' already attached - nothing to do"
                else
                  echo -n "$d" > driver/unbind
                  if [ $? = 0 ]
                  then
                    echo "  successfully detached driver '$drvr'"
                    sleep 1
                    attach "$d" "$DRIVER"
                  else
                    echo "  could not detach driver '$drvr'"
                  fi
                fi
              else
                attach "$d" "$DRIVER"
              fi
            fi
          done
      fi
    fi
  done