#!/bin/sh

# Copyright 2018 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

# UDEV event helper script that restarts a hung network device.

POWER_DOWN_TIME_SECONDS=1
WLAN_POWER_UP_TIME_SECONDS=1
WLAN_REINITIALIZE_TIME_SECONDS=5

set -e

error () {
  logger -t $0 "Error: $1"
  exit 1
}

if [ -n "${1}" ] ; then
  eval $(udevadm info --query=property --path="/sys/class/net/${1}" |
         egrep '^(DEVPATH|DEVTYPE|ID_BUS|INTERFACE|SUBSYSTEM)')
  EVENT=device_hang
fi

if [ "${SUBSYSTEM}" != "net" -o \
     "${EVENT}" != "device_hang" -o \
     -z "${DEVPATH}" ] ; then
  exit 0
fi

logger -t $0 "Restarting network interface ${INTERFACE}"

# The DEVPATH for a network interface should look something like:
#   /devices/pci0000:00/0000:00:1c.0/0000:01:00.0/net/wlan0
if [ $(basename $(dirname "${DEVPATH}")) != 'net' ] ; then
  error "Device path for ${INTERFACE} (${DEVPATH}) is invalid."
fi

device_path=$(readlink -f "/sys${DEVPATH}/../..")
module_name=$(basename $(readlink -f "/sys${DEVPATH}/device/driver/module"))

rmmod "${module_name}"

if [ "${ID_BUS}" = "pci" ] ; then
  device_remove_path="${device_path}/remove"
  bus_rescan_path=$(readlink -f  "${device_path}/../rescan")

  if [ ! -e "${device_remove_path}" ] ; then
    error "Device remove path ${device_remove_path} does not exist"
  fi

  if [ ! -e "${bus_rescan_path}" ] ; then
    error "Bus rescan path ${bus_rescan_path} does not exist"
  fi

  echo 1 > "${device_remove_path}"
  if [ "${DEVTYPE}" = "wlan" ] ; then
    ectool wireless 0xe  # Disable wireless lan.
    ectool wireless 0x6  # Power down wireless lan.
  fi

  sleep ${POWER_DOWN_TIME_SECONDS}

  if [ "${DEVTYPE}" = "wlan" ] ; then
    ectool wireless 0xe  # Power up wireless lan.
    sleep ${WLAN_POWER_UP_TIME_SECONDS}
    ectool wireless 0xf  # Enable wireless lan.

    sleep ${WLAN_REINITIALIZE_TIME_SECONDS}
  fi

  echo 1 > "${bus_rescan_path}"
elif [ "${ID_BUS}" = "usb" ] ; then
  device_authorize_path=$(readlink -f "${device_path}/../authorized")
  echo 0 > "${device_authorize_path}"
  sleep ${POWER_DOWN_TIME_SECONDS}
  echo 1 > "${device_authorize_path}"
else
  error "Bus type ${ID_BUS} is unknown"
fi