servo/servo_server.py

# Copyright (c) 2012 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.
"""Servo Server."""
import datetime
import fcntl
import fnmatch
import logging
import os
import re
import SimpleXMLRPCServer
import time
import usb

import drv as servo_drv
import bbadc
import bbi2c
import bbgpio
import bbuart
import ec3po_interface
import ftdigpio
import ftdii2c
import ftdi_common
import ftdiuart
import i2cbus
import keyboard_handlers
import servo_dev
import servo_interfaces
import servo_postinit
import stm32gpio
import stm32i2c
import stm32uart

HwDriverError = servo_drv.hw_driver.HwDriverError

MAX_I2C_CLOCK_HZ = 100000


class ServodError(Exception):
  """Exception class for servod."""


class Servod(object):
  """Main class for Servo debug/controller Daemon."""

  # This is the key to get the main serial used in the _serialnames dict.
  MAIN_SERIAL = 'main'
  SERVO_MICRO_SERIAL = 'servo_micro'
  CCD_SERIAL = 'ccd'

  # Timeout to wait for interfaces to become available again if reinitialization
  # is taking place. In seconds. This is supposed to recover from brief resets.
  # If the interface disappears for more than 5 seconds, then someone probably
  # intentionally disconnected the device. Servod shouldn't be responsible for
  # waiting for the device during an intentional disconnect.
  INTERFACE_AVAILABILITY_TIMEOUT = 5

  def init_servo_interfaces(self, vendor, product, serialname, interfaces):
    """Init the servo interfaces with the given interfaces.

    We don't use the self._{vendor,product,serialname} attributes because we
    want to allow other callers to initialize other interfaces that may not
    be associated with the initialized attributes (e.g. a servo v4 servod object
    that wants to also initialize a servo micro interface).

    Args:
      vendor: USB vendor id of FTDI device.
      product: USB product id of FTDI device.
      serialname: String of device serialname/number as defined in FTDI
          eeprom.
      interfaces: List of strings of interface types the server will
          instantiate.

    Raises:
      ServodError if unable to locate init method for particular interface.
    """
    # If it is a new device add it to the list
    device = (vendor, product, serialname)
    self.add_device(device)

    # Extend the interface list if we need to.
    interfaces_len = len(interfaces)
    interface_list_len = len(self._interface_list)
    if interfaces_len > interface_list_len:
      self._interface_list += [None] * (interfaces_len - interface_list_len)

    for i, interface in enumerate(interfaces):
      is_ftdi_interface = False
      if type(interface) is dict:
        name = interface['name']
        # Store interface index for those that care about it.
        interface['index'] = i
      elif type(interface) is str:
        if interface == 'dummy':
          # 'dummy' reserves the interface for future use.  Typically the
          # interface will be managed by external third-party tools like
          # openOCD for JTAG or flashrom for SPI.  In the case of servo V4,
          # it serves as a placeholder for servo micro interfaces.
          continue
        name = interface
        is_ftdi_interface = interface.startswith('ftdi')
      else:
        raise ServodError('Illegal interface type %s' % type(interface))

      # servos with multiple FTDI are guaranteed to have contiguous USB PIDs
      product_increment = 0
      if is_ftdi_interface:
        # The interface argument in ftdi initialization is the interface number.
        interface = ((i - 1) % ftdi_common.MAX_FTDI_INTERFACES_PER_DEVICE) + 1
        product_increment = (i - 1) / ftdi_common.MAX_FTDI_INTERFACES_PER_DEVICE
        if product_increment:
          self._logger.info('Use the next FTDI part @ pid = 0x%04x',
                            product + product_increment)

      self._logger.info('Initializing interface %d to %s', i, name)
      try:
        func = getattr(self, '_init_%s' % name)
      except AttributeError:
        raise ServodError('Unable to locate init for interface %s' % name)
      result = func(vendor, product + product_increment, serialname, interface)

      if isinstance(result, tuple):
        result_len = len(result)
        self._interface_list[i:(i + result_len)] = result
      else:
        self._interface_list[i] = result

  def __init__(self, config, vendor, product, serialname=None, interfaces=None,
               board='', model='', version=None, usbkm232=None):
    """Servod constructor.

    Args:
      config: instance of SystemConfig containing all controls for
          particular Servod invocation
      vendor: usb vendor id of FTDI device
      product: usb product id of FTDI device
      serialname: string of device serialname/number as defined in FTDI eeprom.
      interfaces: list of strings of interface types the server will instantiate
      board: board name. e.g. octopus, coral, or scarlet.
      model: model name of a given board. e.g. fleex, ampton, or apel.
      version: String. Servo board version. Examples: servo_v1, servo_v2,
          servo_v2_r0, servo_v3
      usbkm232: String. Optional. Path to USB-KM232 device which allow for
          sending keyboard commands to DUTs that do not have built in
          keyboards. Used in FAFT tests. Use None for on board AVR MCU.
          e.g. '/dev/ttyUSB0' or None.

    Raises:
      ServodError: if unable to locate init method for particular interface
    """
    self._logger = logging.getLogger('Servod')
    self._logger.debug('')
    self._vendor = vendor
    self._product = product
    self._devices = {}
    self._serialnames = {self.MAIN_SERIAL: serialname}
    self._syscfg = config
    # list of objects (Fi2c, Fgpio) to physical interfaces (gpio, i2c) that ftdi
    # interfaces are mapped to
    self._interface_list = []
    # Dict of Dict to map control name, function name to to tuple (params, drv)
    # Ex) _drv_dict[name]['get'] = (params, drv)
    self._drv_dict = {}
    self._base_board = ''
    self._board = board
    if model:
      self._board += '_' + model
    self._model = model
    self._version = version
    self._usbkm232 = usbkm232
    self._keyboard = None
    self._usb_keyboard = None
    if not interfaces:
      try:
        interfaces = servo_interfaces.INTERFACE_BOARDS[board][vendor][product]
      except KeyError:
        interfaces = servo_interfaces.INTERFACE_DEFAULTS[vendor][product]
    self._interfaces = interfaces

    self.init_servo_interfaces(vendor, product, serialname, interfaces)
    servo_postinit.post_init(self)

  def reinitialize(self):
    """Reinitialize all interfaces that support reinitialization"""
    for i, interface in enumerate(self._interface_list):
      if hasattr(interface, 'reinitialize'):
        interface.reinitialize()
      else:
        self._logger.debug('interface %d has no reset functionality', i)
    # Indicate interfaces are safe to use again.
    for device in self._devices.values():
        device.connect()

  def get_servo_interfaces(self, position, size):
    """Get the list of servo interfaces.

    Args:
      position: The index the first interface to get.
      size: The number of the interfaces.
    """
    return self._interface_list[position:(position + size)]

  def set_servo_interfaces(self, position, interfaces):
    """Set the list of servo interfaces.

    Args:
      position: The index the first interface to set.
      interfaces: The list of interfaces to set.
    """
    size = len(interfaces)
    self._interface_list[position:(position + size)] = interfaces

  def close(self):
    """Servod turn down logic."""
    for i, interface in enumerate(self._interface_list):
      self._logger.info('Turning down interface %d' % i)
      if hasattr(interface, 'close'):
        interface.close()

  def get_devices(self):
    return self._devices.values()

  def add_device(self, device):
    if device not in self._devices:
      vid, pid, serial = device
      servod_device = servo_dev.ServoDevice(vid, pid, serial)
      self._devices[device] = servod_device

  def _init_ftdi_dummy(self, vendor, product, serialname, interface):
    """Dummy interface for ftdi devices.

    This is a dummy function specifically for ftdi devices to not initialize
    anything but to help pad the interface list.

    Returns:
      None.
    """
    return None

  def _init_ftdi_gpio(self, vendor, product, serialname, interface):
    """Initialize gpio driver interface and open for use.

    Args:
      interface: interface number of FTDI device to use.

    Returns:
      Instance object of interface.

    Raises:
      ServodError: If init fails
    """
    fobj = ftdigpio.Fgpio(vendor, product, interface, serialname)
    try:
      fobj.open()
    except ftdigpio.FgpioError as e:
      raise ServodError('Opening gpio interface. %s ( %d )' % (e.msg, e.value))

    return fobj

  def _init_stm32_uart(self, vendor, product, serialname, interface):
    """Initialize stm32 uart interface and open for use

    Note, the uart runs in a separate thread.  Users wishing to
    interact with it will query control for the pty's pathname and connect
    with their favorite console program.  For example:
      cu -l /dev/pts/22

    Args:
      interface: dict of interface parameters.

    Returns:
      Instance object of interface

    Raises:
      ServodError: Raised on init failure.
    """
    self._logger.info('Suart: interface: %s' % interface)
    sobj = stm32uart.Suart(vendor, product, interface['interface'], serialname)

    try:
      sobj.run()
    except stm32uart.SuartError as e:
      raise ServodError('Running uart interface. %s ( %d )' % (e.msg, e.value))

    self._logger.info('%s' % sobj.get_pty())
    return sobj

  def _init_stm32_gpio(self, vendor, product, serialname, interface):
    """Initialize stm32 gpio interface.
    Args:
      interface: dict of interface parameters.

    Returns:
      Instance object of interface

    Raises:
      SgpioError: Raised on init failure.
    """
    interface_number = interface
    # Interface could be a dict.
    if type(interface) is dict:
      interface_number = interface['interface']
    self._logger.info('Sgpio: interface: %s' % interface_number)
    return stm32gpio.Sgpio(vendor, product, interface_number, serialname)

  def _init_stm32_i2c(self, vendor, product, serialname, interface):
    """Initialize stm32 USB to I2C bridge interface and open for use

    Args:
      interface: dict of interface parameters.

    Returns:
      Instance object of interface.

    Raises:
      Si2cError: Raised on init failure.
    """
    self._logger.info('Si2cBus: interface: %s' % interface)
    port = interface.get('port', 0)
    return stm32i2c.Si2cBus(vendor, product, interface['interface'], port=port,
                            serialname=serialname)

  def _init_bb_adc(self, vendor, product, serialname, interface):
    """Initalize beaglebone ADC interface."""
    return bbadc.BBadc()

  def _init_bb_gpio(self, vendor, product, serialname, interface):
    """Initalize beaglebone gpio interface."""
    return bbgpio.BBgpio()

  def _init_ftdi_i2c(self, vendor, product, serialname, interface):
    """Initialize i2c interface and open for use.

    Args:
      interface: interface number of FTDI device to use

    Returns:
      Instance object of interface

    Raises:
      ServodError: If init fails
    """
    fobj = ftdii2c.Fi2c(vendor, product, interface, serialname)
    try:
      fobj.open()
    except ftdii2c.Fi2cError as e:
      raise ServodError('Opening i2c interface. %s ( %d )' % (e.msg, e.value))

    # Set the frequency of operation of the i2c bus.
    # TODO(tbroch) make configureable
    fobj.setclock(MAX_I2C_CLOCK_HZ)

    return fobj

  # TODO (sbasi) crbug.com/187489 - Implement bb_i2c.
  def _init_bb_i2c(self, interface):
    """Initalize beaglebone i2c interface."""
    return bbi2c.BBi2c(interface)

  def _init_dev_i2c(self, vendor, product, serialname, interface):
    """Initalize Linux i2c-dev interface."""
    return i2cbus.I2CBus('/dev/i2c-%d' % interface['bus_num'])

  def _init_ftdi_uart(self, vendor, product, serialname, interface):
    """Initialize ftdi uart inteface and open for use

    Note, the uart runs in a separate thread (pthreads).  Users wishing to
    interact with it will query control for the pty's pathname and connect
    with there favorite console program.  For example:
      cu -l /dev/pts/22

    Args:
      interface: interface number of FTDI device to use

    Returns:
      Instance object of interface

    Raises:
      ServodError: If init fails
    """
    fobj = ftdiuart.Fuart(vendor, product, interface, serialname)
    try:
      fobj.run()
    except ftdiuart.FuartError as e:
      raise ServodError('Running uart interface. %s ( %d )' % (e.msg, e.value))

    self._logger.info('%s' % fobj.get_pty())
    return fobj

  # TODO (sbasi) crbug.com/187492 - Implement bbuart.
  def _init_bb_uart(self, vendor, product, serialname, interface):
    """Initalize beaglebone uart interface."""
    logging.debug('UART INTERFACE: %s', interface)
    return bbuart.BBuart(interface)

  def _init_ftdi_gpiouart(self, vendor, product, serialname, interface):
    """Initialize special gpio + uart interface and open for use

    Note, the uart runs in a separate thread (pthreads).  Users wishing to
    interact with it will query control for the pty's pathname and connect
    with there favorite console program.  For example:
      cu -l /dev/pts/22

    Args:
      interface: interface number of FTDI device to use

    Returns:
      Instance objects of interface

    Raises:
      ServodError: If init fails
    """
    fgpio = self._init_ftdi_gpio(vendor, product, serialname, interface)
    fuart = ftdiuart.Fuart(vendor, product, interface, serialname, fgpio._fc)
    try:
      fuart.run()
    except ftdiuart.FuartError as e:
      raise ServodError('Running uart interface. %s ( %d )' % (e.msg, e.value))

    self._logger.info('uart pty: %s' % fuart.get_pty())
    return fgpio, fuart

  def _init_ec3po_uart(self, vendor, product, serialname, interface):
    """Initialize EC-3PO console interpreter interface.

    Args:
      interface: A dictionary representing the interface.

    Returns:
      An EC3PO object representing the EC-3PO interface or None if there's no
      interface for the USB PD UART.
    """
    device = (vendor, product, serialname)
    raw_uart_name = interface['raw_pty']
    raw_uart_source = interface['source']
    if self._syscfg.is_control(raw_uart_name):
      raw_ec_uart = self.get(raw_uart_name)
      return ec3po_interface.EC3PO(raw_ec_uart, raw_uart_source, device)
    else:
      # The overlay doesn't have the raw PTY defined, therefore we can skip
      # initializing this interface since no control relies on it.
      self._logger.debug(
          'Skip initializing EC3PO for %s, no control specified.',
          raw_uart_name)
      return None

  def _camel_case(self, string):
    output = ''
    for s in string.split('_'):
      if output:
        output += s.capitalize()
      else:
        output = s
    return output

  def clear_cached_drv(self):
    """Clear the cached drivers.

    The drivers are cached in the Dict _drv_dict when a control is got or set.
    When the servo interfaces are relocated, the cached values may become wrong.
    Should call this method to clear the cached values.
    """
    self._drv_dict = {}

  def _get_servo_specific_param(self, params, param_key, control_name):
    """Get |param_key| from params by looking for servo specific params first.

    Find the candidate servos.  Using servo_v4 with a servo_micro connected as
    example, the following shows the priority for selecting the interface.

    1. The full name. (e.g. - 'servo_v4_with_servo_micro_interface')
    2. servo_micro_interface
    3. servo_v4_interface
    4. Fallback to the default, interface.

    Args:
      params: params dictionary for a control
      param_key: identifier in the params dictionary to look for
      control_name: control name the params correspond to

    Returns:
      The best suited param value for param_key given the servo type or
      None if even the default is not defined.
    """
    candidates = [self._version]
    if '_with_' in self._version:
      v4, raw_dut_device = self._version.split('_with_')
      dut_devices = raw_dut_device.split('_and_')
      # NOTE(coconutruben): all of this nonsense is going away with the new
      # servod and is to bridge the time until then. Please forgive the below
      # until then.
      if '.' in control_name:
        # In the current implementation, the only case where a '.' (a prefix)
        # is in the control name is when there is a dual instance with micro and
        # ccd on a v4.
        dut_device = dut_devices[1]
      else:
        # In the normal control name, we need to make sure the version used
        # does not include the potential _and_ portion from a dual instance.
        dut_device = dut_devices[0]
      candidates.extend([dut_device, v4])
    candidates = ['%s_%s' % (c, param_key) for c in candidates]
    candidates.append(param_key)
    for c in candidates:
      if c in params:
        self._logger.debug('Using %s parameter.', c)
        return params[c]
    self._logger.error('Unable to determine %s for %s', param_key, control_name)
    self._logger.error('params: %r', params)
    return None

  def _get_param_drv(self, control_name, is_get=True):
    """Get access to driver for a given control.

    Note, some controls have different parameter dictionaries for 'getting' the
    control's value versus 'setting' it.  Boolean is_get distinguishes which is
    being requested.

    Args:
      control_name: string name of control
      is_get: boolean to determine

    Returns:
      tuple (param, drv) where:
        param: param dictionary for control
        drv: instance object of driver for particular control

    Raises:
      ServodError: Error occurred while examining params dict
    """
    self._logger.debug('')
    # if already setup just return tuple from driver dict
    if control_name in self._drv_dict:
      if is_get and ('get' in self._drv_dict[control_name]):
        return self._drv_dict[control_name]['get']
      if not is_get and ('set' in self._drv_dict[control_name]):
        return self._drv_dict[control_name]['set']

    params = self._syscfg.lookup_control_params(control_name, is_get)

    # Get the most suitable drv given the servo instance.
    drv_name = self._get_servo_specific_param(params, 'drv', control_name)
    if drv_name == 'na':
      # 'na' drv can be used to selectively turn controls into noops for
      # a given servo hardware. Ensure that there is an interface.
      params.setdefault('interface', 'servo')
      self._logger.debug('Setting interface to default to %r for %r unless '
                         ' defined  in params, as drv is %r.', 'servo',
                         control_name, 'na')
      # Setting input_type to str allows all inputs through enabling a true noop
      params.update({'input_type': 'str'})
    interface_id = self._get_servo_specific_param(params, 'interface',
                                                  control_name)
    if None in [drv_name, interface_id]:
      raise ServodError('No drv/interface for control %r found' % control_name)

    if interface_id == 'servo':
      interface = self
    else:
      index = int(interface_id)
      interface = self._interface_list[index]

    device_info = None
    if hasattr(interface, 'get_device_info'):
      device_info = interface.get_device_info()
    drv_module = getattr(servo_drv, drv_name)
    drv_class = getattr(drv_module, self._camel_case(drv_name))
    drv = drv_class(interface, params)
    if control_name not in self._drv_dict:
      self._drv_dict[control_name] = {}
    if is_get:
      self._drv_dict[control_name]['get'] = (params, drv, device_info)
    else:
      self._drv_dict[control_name]['set'] = (params, drv, device_info)
    return (params, drv, device_info)

  def doc_all(self):
    """Return all documenation for controls.

    Returns:
      string of <doc> text in config file (xml) and the params dictionary for
      all controls.

      For example:
      warm_reset             :: Reset the device warmly
      ------------------------> {'interface': '1', 'map': 'onoff_i', ... }
    """
    return self._syscfg.display_config()

  def doc(self, name):
    """Retreive doc string in system config file for given control name.

    Args:
      name: name string of control to get doc string

    Returns:
      doc string of name

    Raises:
      NameError: if fails to locate control
    """
    self._logger.debug('name(%s)' % (name))
    if self._syscfg.is_control(name):
      return self._syscfg.get_control_docstring(name)
    else:
      raise NameError('No control %s' % name)

  def safe_switch_usbkey_power(self, power_state, _=None):
    """Toggle the usb power safely.

    Args:
      power_state: The setting to set for the usbkey power.
      _: to conform to current API

    Returns:
      An empty string to appease the xmlrpc gods.
    """
    self.set('image_usbkey_pwr', power_state)
    return ''

  def safe_switch_usbkey(self, mux_direction, _=0):
    """Toggle the usb direction safely.

    Args:
      mux_direction: "servo_sees_usbkey" or "dut_sees_usbkey".
      _: to conform to current API

    Returns:
      An empty string to appease the xmlrpc gods.
    """
    self.set('image_usbkey_direction', mux_direction)
    return ''

  def probe_host_usb_dev(self, _=0):
    """Probe the USB disk device plugged in the servo from the host side.

    Args:
      _: to conform to current API

    Returns:
      USB disk path if one and only one USB disk path is found, otherwise an
    """
    return self.get('image_usbkey_dev')

  def download_image_to_usb(self, image_path, _=0):
    """Download image and save to the USB device found by probe_host_usb_dev.
    If the image_path is a URL, it will download this url to the USB path;
    otherwise it will simply copy the image_path's contents to the USB path.

    Args:
      image_path: path or url to the recovery image.
      _: to conform to current API

    Returns:
      True|False: True if process completed successfully, False if error
                        occurred.
    """
    try:
      self.set('download_image_to_usb_dev', image_path)
      return True
    except Exception:
      return False

  def make_image_noninteractive(self):
    """Makes the recovery image noninteractive.

    A noninteractive image will reboot automatically after installation
    instead of waiting for the USB device to be removed to initiate a system
    reboot.

    Mounts partition 1 of the image stored on usb_dev and creates a file
    called "non_interactive" so that the image will become noninteractive.

    Returns:
      True|False: True if process completed successfully, False if error
                        occurred.
    """
    try:
      usb_dev = self.get('image_usbkey_dev')
      usb_dev_partition = '%s1' % usb_dev
      self.set('make_usb_dev_image_noninteractive', usb_dev_partition)
      return True
    except Exception:
      return False

  def set_get_all(self, cmds):
    """Set &| get one or more control values.

    Args:
      cmds: list of control[:value] to get or set.

    Returns:
      rv: list of responses from calling get or set methods.
    """
    rv = []
    for cmd in cmds:
      if ':' in cmd:
        (control, value) = cmd.split(':', 1)
        rv.append(self.set(control, value))
      else:
        rv.append(self.get(cmd))
    return rv

  def add_serial_number(self, name, serial_number):
    """Adds the serial number to the _serialnames dictionary.

    Args:
      name: A string which is the key into the _serialnames dictionary.
      serial_number: A string which is the key into the _serialnames dictionary.
    """
    self._serialnames[name] = serial_number
    self._logger.debug('Added %s %s to serialnames %r', name, serial_number,
                       self._serialnames)

  def get_serial_number(self, name):
    """Returns the desired serial number from the serialnames dict.

    Args:
      name: A string which is the key into the _serialnames dictionary.

    Returns:
       A string containing the serial number or "unknown".
    """
    # Remove the prefix from the serialname control. Serialnames are
    # universal. It doesn't matter what the prefix is.
    # The prefix is separated from the main control with '.'
    name = name.split('.', 1)[-1]

    if not name:
      name = 'main'
    try:
      return self._serialnames[name]
    except KeyError:
      self._logger.debug("'%s_serialname' not found!", name)
      return 'unknown'

  def get(self, name):
    """Get control value.

    Args:
      name: name string of control

    Returns:
      Response from calling drv get method.  Value is reformatted based on
      control's dictionary parameters

    Raises:
      HwDriverError: Error occurred while using drv
      ServodError: if interfaces are not available within timeout period
    """
    self._logger.debug('name(%s)' % (name))
    # This route is to retrieve serialnames on servo v4, which
    # connects to multiple servo-micros or CCD, like the controls,
    # 'ccd_serialname', 'servo_micro_for_soraka_serialname', etc.
    # TODO(aaboagye): Refactor it.
    if 'serialname' in name:
      return self.get_serial_number(name.split('serialname')[0].strip('_'))

    (param, drv, device) = self._get_param_drv(name)
    if device in self._devices:
      self._devices[device].wait(self.INTERFACE_AVAILABILITY_TIMEOUT)
    try:
      val = drv.get()
      rd_val = self._syscfg.reformat_val(param, val)
      self._logger.debug('%s = %s' % (name, rd_val))
      return rd_val
    except AttributeError, error:
      self._logger.error('Getting %s: %s' % (name, error))
      raise
    except HwDriverError:
      self._logger.error('Getting %s' % (name))
      raise
    # pylint: disable=broad-except
    # This acts as a safety to inform the user of errors that should not
    # be happening/require more investigation.
    except Exception:
      self._logger.error('Unknown issue getting %s. Please take a look.', name)
      raise

  def get_all(self, verbose):
    """Get all controls values.

    Args:
      verbose: Boolean on whether to return doc info as well

    Returns:
      string creating from trying to get all values of all controls.  In case of
      error attempting access to control, response is 'ERR'.
    """
    rsp = []
    for name in self._syscfg.syscfg_dict['control']:
      self._logger.debug('name = %s' % name)
      try:
        value = self.get(name)
      except Exception:
        value = 'ERR'
        pass
      if verbose:
        rsp.append('GET %s = %s :: %s' % (name, value, self.doc(name)))
      else:
        rsp.append('%s:%s' % (name, value))
    return '\n'.join(sorted(rsp))

  def set(self, name, wr_val_str):
    """Set control.

    Args:
      name: name string of control
      wr_val_str: value string to write.  Can be integer, float or a
          alpha-numerical that is mapped to a integer or float.

    Raises:
      HwDriverError: Error occurred while using driver
      ServodError: if interfaces are not available within timeout period
    """
    self._logger.debug('name(%s) wr_val(%s)' % (name, wr_val_str))
    (params, drv, device) = self._get_param_drv(name, False)
    if device in self._devices:
      self._devices[device].wait(self.INTERFACE_AVAILABILITY_TIMEOUT)
    wr_val = self._syscfg.resolve_val(params, wr_val_str)
    try:
      drv.set(wr_val)
    except HwDriverError:
      self._logger.error('Setting %s -> %s' % (name, wr_val_str))
      raise
    # pylint: disable=broad-except
    # This acts as a safety to inform the user of errors that should not
    # be happening/require more investigation.
    except Exception:
      self._logger.error('Unknown issue setting %s -> %s. Please take a look.',
                         name, wr_val_str)
      raise
    # TODO(crbug.com/841097) Figure out why despite allow_none=True for both
    # xmlrpc server & client I still have to return something to appease the
    # marshall/unmarshall
    return True

  def hwinit(self, verbose=False):
    """Initialize all controls.

    These values are part of the system config XML files of the form
    init=<value>.  This command should be used by clients wishing to return the
    servo and DUT its connected to a known good/safe state.

    Note that initialization errors are ignored (as in some cases they could
    be caused by DUT firmware deficiencies). This might need to be fine tuned
    later.

    Args:
      verbose: boolean, if True prints info about control initialized.
        Otherwise prints nothing.

    Returns:
      This function is called across RPC and as such is expected to return
      something unless transferring 'none' across is allowed. Hence adding a
      dummy return value to make things simpler.
    """
    for control_name, value in self._syscfg.hwinit:
      try:
        # Workaround for bug chrome-os-partner:42349. Without this check, the
        # gpio will briefly pulse low if we set it from high to high.
        if self.get(control_name) != value:
          self.set(control_name, value)
        if verbose:
          self._logger.info('Initialized %s to %s', control_name, value)
      except Exception as e:
        self._logger.error(
            'Problem initializing %s -> %s', control_name, value)
        self._logger.error(str(e))
        self._logger.error('Please consider verifying the logs and if the '
                           'error is not just a setup issue, consider filing '
                           'a bug. Also checkout go/servo-ki.')

    # If there is the control of 'active_v4_device', set active_v4_device to
    # the default device as initialization.
    try:
      self.set('active_v4_device', 'default')
    except NameError as e:
      # If the control does not exist, just pass it.
      pass
    except servo_drv.active_v4_device.activeV4DeviceError as e:
      self._logger.error(str(e))

    return True

  def echo(self, echo):
    """Dummy echo function for testing/examples.

    Args:
      echo: string to echo back to client
    """
    self._logger.debug('echo(%s)' % (echo))
    return 'ECH0ING: %s' % (echo)

  def get_board(self):
    """Return the board specified at startup, if any."""
    return self._board

  def get_base_board(self):
    """Returns the board name of the base if present.

    Returns:
      A string of the board name, or '' if not present.
    """
    # The value is set in servo_postinit.
    return self._base_board

  def get_version(self):
    """Get servo board version."""
    return self._version

  def power_long_press(self):
    """Simulate a long power button press."""
    # After a long power press, the EC may ignore the next power
    # button press (at least on Alex).  To guarantee that this
    # won't happen, we need to allow the EC one second to
    # collect itself.
    return self.set('power_key', 'long_press')

  def power_normal_press(self):
    """Simulate a normal power button press."""
    return self.set('power_key', 'press')

  def power_short_press(self):
    """Simulate a short power button press."""
    return self.set('power_key', 'short_press')

  def power_key(self, press_secs=''):
    """Simulate a power button press.

    Args:
      press_secs: Time in seconds to simulate the keypress.
    """
    return self.set('power_key', 'press' if press_secs is '' else press_secs)

  def ctrl_d(self, press_secs=''):
    """Simulate Ctrl-d simultaneous button presses."""
    return self.set('ctrl_d', 'tab' if press_secs is '' else press_secs)

  def ctrl_u(self, press_secs=''):
    """Simulate Ctrl-u simultaneous button presses."""
    return self.set('ctrl_u', 'tab' if press_secs is '' else press_secs)

  def ctrl_enter(self, press_secs=''):
    """Simulate Ctrl-enter simultaneous button presses."""
    return self.set('ctrl_enter', 'tab' if press_secs is '' else press_secs)

  def ctrl_key(self, press_secs=''):
    """Simulate Enter key button press."""
    return self.set('ctrl_key', 'tab' if press_secs is '' else press_secs)

  def enter_key(self, press_secs=''):
    """Simulate Enter key button press."""
    return self.set('enter_key', 'tab' if press_secs is '' else press_secs)

  def refresh_key(self, press_secs=''):
    """Simulate Refresh key (F3) button press."""
    return self.set('refresh_key', 'tab' if press_secs is '' else press_secs)

  def ctrl_refresh_key(self, press_secs=''):
    """Simulate Ctrl and Refresh (F3) simultaneous press.

    This key combination is an alternative of Space key.
    """
    return self.set('ctrl_refresh_key', ('tab' if press_secs is '' else
                                         press_secs))

  def imaginary_key(self, press_secs=''):
    """Simulate imaginary key button press.

    Maps to a key that doesn't physically exist.
    """
    return self.set('imaginary_key', 'tab' if press_secs is '' else press_secs)

  def sysrq_x(self, press_secs=''):
    """Simulate Alt VolumeUp X simultaneous press.

    This key combination is the kernel system request (sysrq) x.
    """
    return self.set('sysrq_x', 'tab' if press_secs is '' else press_secs)

  def get_servo_serials(self):
    """Return all the serials associated with this process."""
    return self._serialnames


def test():
  """Integration testing.

  TODO(tbroch) Enhance integration test and add unittest (see mox)
  """
  logging.basicConfig(
      level=logging.DEBUG,
      format='%(asctime)s - %(name)s - ' + '%(levelname)s - %(message)s')
  # configure server & listen
  servod_obj = Servod(1)
  # 5 == number of interfaces on a FT4232H device
  for i in xrange(1, 5):
    if i == 2:
      # its an i2c interface ... see __init__ for details and TODO to make
      # this configureable
      servod_obj._interface_list[i].wr_rd(0x21, [0], 1)
    else:
      # its a gpio interface
      servod_obj._interface_list[i].wr_rd(0)

  server = SimpleXMLRPCServer.SimpleXMLRPCServer(('localhost', 9999),
                                                 allow_none=True)
  server.register_introspection_functions()
  server.register_multicall_functions()
  server.register_instance(servod_obj)
  logging.info('Listening on localhost port 9999')
  server.serve_forever()


if __name__ == '__main__':
  test()

  # simple client transaction would look like
  """remote_uri = 'http://localhost:9999' client = xmlrpclib.ServerProxy(remote_uri, verbose=False) send_str = "Hello_there" print "Sent " + send_str + ", Recv " + client.echo(send_str)

  """