displaylink 1.3.52 udev rule and helper script

99-displaylink.rules

# Copyright (c) 2016 DisplayLink (UK) Ltd.
# File autogenerated by udev-installer.sh script

ACTION=="add", SUBSYSTEM=="usb", DRIVERS=="usb", ATTR{idVendor}=="17e9", IMPORT{builtin}="usb_id", ENV{DISPLAYLINK_DEVNAME}="$env{DEVNAME}", ENV{DISPLAYLINK_DEVICE_ID}="$env{ID_BUS}-$env{BUSNUM}-$env{DEVNUM}-$env{ID_SERIAL}", ENV{REMOVE_CMD}="/opt/displaylink/udev.sh $root $env{DISPLAYLINK_DEVICE_ID} $env{DISPLAYLINK_DEVNAME}"

ACTION=="add", SUBSYSTEM=="usb", DRIVERS=="usb", ATTRS{idVendor}=="17e9", ATTR{bInterfaceClass}=="ff", ATTR{bInterfaceProtocol}=="03", IMPORT{parent}="DISPLAYLINK*", RUN+="/opt/displaylink/udev.sh $root $env{DISPLAYLINK_DEVICE_ID} $env{DISPLAYLINK_DEVNAME}"

udev.sh

#!/bin/sh
# Copyright (c) 2016 DisplayLink (UK) Ltd.
# File autogenerated by udev-installer.sh script

get_displaylink_dev_count()
{
   cat /sys/bus/usb/devices/*/idVendor | grep 17e9 | wc -l
}

get_displaylink_symlink_count()
{
  root=$1

  if [ ! -d "$root/displaylink/by-id" ]; then
    echo "0"
    return
  fi

  for f in $(find $root/displaylink/by-id -type l -exec realpath {} \; 2> /dev/null); do
    test -c $f && echo $f;
  done | wc -l
}

start_displaylink()
{
  if [ "$(get_displaylink_dev_count)" != "0" ]; then
    start_service
  fi
}

stop_displaylink()
{
  root=$1

  if [ "$(get_displaylink_symlink_count $root)" = "0" ]; then
    stop_service
  fi
}

create_displaylink_symlink()
{
  root=$1
  device_id=$2
  devnode=$3

  mkdir -p $root/displaylink/by-id
  ln -sf $devnode $root/displaylink/by-id/$device_id
}

unlink_displaylink_symlink()
{
   root=$1
   device_id=$2

   unlink $root/displaylink/by-id/$device_id 2> /dev/null
   (cd $root; rmdir -p --ignore-fail-on-non-empty displaylink/by-id)
}

main()
{
  action=$1
  root=$2
  device_id=$3
  devnode=$4

  if [ "$action" = "add" ]; then
    create_displaylink_symlink $root $device_id $devnode
    start_displaylink
  elif [ "$action" = "remove" ]; then
    unlink_displaylink_symlink "$root" "$device_id"
    stop_displaylink "$root"
  fi
}

start_service()
{
  start dlm
}

stop_service()
{
  stop dlm
}
main $ACTION $1 $2 $3