#!/usr/bin/env python2
# Copyright 2014 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.
"""Flash PD PSU RW firmware over the USBPD comm channel using console.

  Example:
    util/flash_pd.py ./build/zinger/ec.RW.bin
"""

import array
import errno
import logging
import optparse
import os
import re
import socket
import sys
import time

import serial
# TODO(tbroch): Discuss adding hdctools as an EC package RDEPENDS
from servo import client
from servo import multiservo

VERSION = '0.0.2'

# RW area is half of the 32-kB
MAX_FW_SIZE = 16 * 1024
# 20 first bytes of SHA-256 of RW when erased (set to all F's)
ERASED_RW_HASH = 'd86670be 559860c7 2b2149e8 d2ae1104 9550e093'

class FlashPDError(Exception):
  """Exception class for flash_pd utility."""


class FlashPD(client.ServoClient):
  """class to flash PD MCU.

    Note, Some designs(samus) have multiple embedded MCUs.  In that case
    the convention is to name the pty associated with usbpd as
    'usbpd_uart_pty'.  In the case where there is only one MCU we prefer
    'usbpd_uart_pty' but will also associate 'ecu_uart_pty' with having
    capability to flash the USB-PD capable PSU(zinger).

  Attributes:
    _options : Values instance from optparse.

  Public Methods:
    expect        :  Examine console output for an expected response.
    flash_command :  Write a PD flash command and interrogate its result.
    get_version   :  Retrieve current version of PD FW.
  """

  def __init__(self, options):
    """Constructor.

    Args:
      options : Values instance from optparse.

    Raises:
      FlashPDError: If unable to determine the console pty
    """
    super(FlashPD, self).__init__(host=options.server, port=options.port)
    self._options = options
    self._serial = None

    try:
      pty = self.get('usbpd_uart_pty')
    except socket.error as e:
      raise FlashPDError('Can\'t connect to servod :: %s' % e)
    except client.ServoClientError:
      pty = self.get('ec_uart_pty')
    if not pty:
      raise FlashPDError('Unable to determine EC uart from servod')

    logging.debug('Opening serial connection to %s', pty)
    try:
      self._serial = serial.Serial(pty, timeout=1)
    except OSError as e:
      if e.errno == errno.EAGAIN:
        # try twice if already open EAGAIN failure causes disconnect.
        self._serial = serial.Serial(pty, timeout=1)
      else:
        raise FlashPDError('%s' % e)

    # quiet other channels that might pollute console.
    self._serial.write('chan 1\n')
    self._serial.flushOutput()
    self._serial.flushInput()

  def __del__(self):
    """Deconstructor."""
    if self._serial:
      for l in self._serial:
        logging.debug('flash: %s', l)
      self._serial.write('chan 0xffffffff\n')
      self._serial.write('chan restore\n')
      self._serial.close()

  def expect(self, val, timeout=5):
    """Scan serial output for particular string.

    Args:
      val     : string to look for
      timeout : integer seconds to look before timing out.

    Returns:
      tuple : boolean if 'val' found in console output.
              string of line that had 'val' in it.
    """
    done = False
    deadline = time.time() + timeout
    while not done and (time.time() < deadline):
      l = None
      for l in self._serial:
        done = val in l
        logging.debug('Is %s in: %s', val, l)
        if done or time.time() > deadline:
          break
    if not done:
      logging.debug("Expect '%s' missing", val)
    return (done, l)

  def pd_command(self, cmd, expect='DONE 0', retries=2, ignore_fail=False):
    """Send PD command and interrogate output.

    Args:
      cmd         : string of 'pd <port>' command to execute
      expect      : string of expected response after 'cmd'
      retries     : integer number of times to repeat command if it fails.
      ignore_fail : boolean to ignore failure

    Returns:
      tuple :
        found : boolean, whether response matches expected.
        line  : string of line returned by expect method.

    Raises:
      FlashPDError: if command failed to match expected return string after
        retries.
    """
    tries = retries + 1
    for i in xrange(tries):
      self._serial.write('pd %d %s\n' % (self._options.multiport, cmd))
      (found, line) = self.expect(expect)
      if i:
        time.sleep(1)
        logging.debug("pd cmd Retry%d for '%s'", i, cmd)
      if found:
        break
    if (i + 1) == tries and not found and not ignore_fail:
      raise FlashPDError("Failed pd cmd: '%s' after %d retries\n" %
                         (cmd, retries))
    return (found, line)

  def flash_command(self, cmd, expect='DONE 0', retries=2, ignore_fail=False):
    """Helper method."""
    flash_cmd = 'flash %s' % cmd
    return self.pd_command(flash_cmd, expect, retries, ignore_fail)

  def get_version(self):
    """Retreive PSU firmware version.

    Looks like: 'version: zinger_v1.1.1917-bfd'

    Returns:
      version : string of version
    Raises:
      FlashPDError : if can't determine version
    """
    (found, line) = self.flash_command('version', expect='version:')
    logging.debug('is version in: %s', line)
    m = False
    if found:
      m = re.match(r'.*version:\s+(\w+_v\d+\.\d+\.\d+-\S+).*', line)
    if not m:
      raise FlashPDError('Unable to determine PD FW version')
    return m.group(1)

  def reboot(self):
    """Reboot PSU.

    Use 'version' to poll for success after DONE encountered.
    Raises:
      FlashPDError : If unable to reboot
    """
    self.flash_command('reboot', expect=r'DONE', retries=0)
    self.flash_command('version', retries=10)


def flash_pd(options):
  """Flash power delivery firmware."""

  ec = FlashPD(options)

  with open(options.firmware) as fd:
    fw = fd.read()
    fw_size = len(fw)
    # The RW firmware should be already padded and signed
    if fw_size != MAX_FW_SIZE:
      raise FlashPDError('Bad RW firmware size %d/%d' % (fw_size, MAX_FW_SIZE))

    words = array.array('I', fw)

  logging.info('Current PD FW version is %s', ec.get_version())
  if options.versiononly:
    return

  logging.info('Flashing %d bytes', fw_size)

  # reset flashed signature to reboot in RO
  ec.flash_command('signature')
  # reboot in RO
  ec.reboot()
  # erase all RW partition
  ec.flash_command('erase')

  # try info command and guarantee we're in RO
  (done, line) = ec.flash_command('info', expect=r'INFO')
  m = re.match(r'INFO.*(18d1\S{4})', line)
  if done and m:
    done = ec.expect('DONE 0')
    in_rw = int(m.group(1), 16) & 0x1
    if in_rw:
      raise FlashPDError('Not in RO after erase')
  # Google UFP devices share their hash to DFP after info command so check it
  (done, _) = ec.pd_command('hash', expect=ERASED_RW_HASH)

  if not done:
    raise FlashPDError('Erase failed')

  logging.info('Successfully erased flash.')

  if options.eraseonly:
    ec.reboot()
    logging.info('After erase, FW version is %s', ec.get_version())
    return

  # write firmware content
  for i in xrange(len(words) / 6):
    chunk = words[i * 6: (i + 1) * 6]
    cmd = ' '.join(['%08x' % (w) for w in chunk])
    ec.flash_command(cmd)
    if not i % 0x10:
      logging.info('Chunk %d of %d done.', i, len(words) / 6)
  # write the remaining words
  chunk = words[len(words) / 6 * 6:]
  cmd = ' '.join(['%08x' % (w) for w in chunk])
  ec.flash_command(cmd)

  # reboot in RW
  ec.reboot()

  logging.info('Flashing DONE.')
  logging.info('New PD FW version is %s', ec.get_version())


def parse_args():
  """Parse commandline arguments.

  Note, reads sys.argv directly

  Returns:
    options : dict of from optparse.parse_args().

  Raises:
    FlashPDError : If problems with arguments
  """
  description = (
      '%prog [<switch args>] <firmware.bin>'
      '\n'
      '%prog is a utility for flashing the USB-PD charger RW firmware over '
      'the USB-PD communication channel using PD MCU console commands.'
      )
  examples = (
      '\nExamples:\n'
      '   %prog build/zinger/ec.RW.flat\n'
      )
  parser = optparse.OptionParser(version='%prog ' + VERSION)
  parser.description = description
  parser.add_option('-d', '--debug', action='store_true', default=False,
                    help='enable debug messages.')
  parser.add_option('-s', '--server', help='host where servod is running',
                    default=client.DEFAULT_HOST)
  parser.add_option('-p', '--port', default=client.DEFAULT_PORT, type=int,
                    help='port servod is listening on.')
  parser.add_option('-m', '--multiport', default=0, type=int,
                    help='If design has multiple type-C ports, this identifies '
                    'which one has USB PD PSU.')
  parser.add_option('', '--timeout', default=5, type=int,
                    help='Timeout seconds to wait for console output.')
  parser.add_option('', '--eraseonly', action='store_true', default=False,
                    help='Only erase RW portion and exit.')
  parser.add_option('-V', '--versiononly', action='store_true', default=False,
                    help='Only read version and exit.')
  multiservo.add_multiservo_parser_options(parser)

  parser.set_usage(parser.get_usage() + examples)
  (options, args) = parser.parse_args()

  # TODO(tbroch) Add this once we refactor module to ease use in scripts.
  if options.name:
    raise NotImplementedError('Multiservo support TBD')

  # Add after to enumerate options.firmware but outside 'help' generation
  parser.add_option('-f', '', action='store', type='string', dest='firmware')

  if len(args) != 1:
    raise FlashPDError('Must supply power delivery firmware to write.')

  options.firmware = args[0]
  if not os.path.exists(options.firmware):
    raise FlashPDError('Unable to find file %s' % options.firmware)

  fw_size = os.path.getsize(options.firmware)
  if fw_size > MAX_FW_SIZE:
    raise FlashPDError('Firmware too large %d/%d' % (fw_size, MAX_FW_SIZE))

  return options


def main_function():
  options = parse_args()

  loglevel = logging.INFO
  log_format = '%(asctime)s - %(name)s - %(levelname)s'
  if options.debug:
    loglevel = logging.DEBUG
    log_format += ' - %(filename)s:%(lineno)d:%(funcName)s'
  log_format += ' - %(message)s'
  logging.basicConfig(level=loglevel, format=log_format)

  flash_pd(options)


def main():
  """Main function wrapper to catch exceptions properly."""
  try:
    main_function()
  except KeyboardInterrupt:
    sys.exit(0)
  except FlashPDError as e:
    print 'Error: ', e.message
    sys.exit(1)

if __name__ == '__main__':
  main()
