scripts/asoc_dapm_graph

#!/usr/bin/env python
# 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.

"""Dump DAPM widgets status as a 'dot' graph file.

To generate widget status for a device run
  ssh $REMOTE asoc_dapm_graph > dot.txt && dot -Kfdp -Tpng dot.txt -o widgets.png
"""

from __future__ import print_function
import os
import platform
import re
import sys
import time

ROOTDIR = '/sys/kernel/debug/asoc/'
# Some widget names are widely used by many codecs, adding them to the graph
# creates a mess.
IGNORE_WIDGETS = ('Playback', 'Capture', 'bias_level')


def handle_widgets(path):
  """Reads DAPM widget information from sysfs and generates dot graph entry.

  Args:
    path: path for sysfs file that exports information about DAPM widget.
  """
  for w in os.listdir(path):
    if w in IGNORE_WIDGETS:
      continue

    with open(os.path.join(path, w)) as f:
      lines = f.readlines()

    active = lines[0].startswith(w + ': On ')
    color = 'green' if active else 'red'
    print('\t"%s" [color = %s]' % (w, color))

    for l in lines[1:]:
      l = l.rstrip()
      # The string format is (in/out) "switch" "widget".
      edge = list(filter(None, re.split(r' (in|out)  "(.+)" "(.+)"', l)))

      if len(edge) != 3:
        continue

      direction = edge[0]
      source = edge[2]

      if source in IGNORE_WIDGETS:
        continue

      # We need to output the edge only once (e.g. inbound).
      if direction != 'in':
        continue

      print('\t"%s" -> "%s"' % (source, w))


def handle_card(path):
  """Generates dot graph file for the given card.

  Args:
    path: path to sysfs directory that exports DAPM information for a sound card.
  """
  host = platform.uname()[1]
  print('// Generated %s at %s.' % (time.strftime("%c"), host))
  print('// To visualize the graph run "dot -Kfdp -Tpng $SCRIPT_OUTPUT_FILE -o widgets.png".')
  print('digraph G {')
  print('\tbgcolor = grey')
  for root, dirs, files in os.walk(path):
    if 'dapm' in dirs:
      handle_widgets(os.path.join(root, 'dapm'))
      dirs.remove('dapm')
  print('}')


def main(argv):
  for c in os.listdir(ROOTDIR):
    path = os.path.join(ROOTDIR, c)
    # We assume that directories in ROOTDIR are cards.
    if os.path.isdir(path):
      handle_card(path)
      sys.exit(0)

  print('No cards found', file=sys.stderr)
  sys.exit(1)


if __name__ == '__main__':
  main(sys.argv[1:])