Platform.py

# Copyright (c) 2014 Adafruit Industries
# Author: Tony DiCola

# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:

# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.

# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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# SOFTWARE.
import platform
import re

# Platform identification constants.
UNKNOWN          = 0
RASPBERRY_PI     = 1
BEAGLEBONE_BLACK = 2


def platform_detect():
	"""Detect if running on the Raspberry Pi or Beaglebone Black and return the
	platform type.  Will return RASPBERRY_PI, BEAGLEBONE_BLACK, or UNKNOWN."""

	# TODO: Is there a better way to check if running on BBB or Pi?  Relying on
	# the architecture name is brittle because new boards running armv6 or armv7
	# might come along and conflict with this simple identification scheme.  One
	# option might be switching to read /proc/cpuinfo.
	plat = platform.platform()

	# Handle Raspberry Pi
	# Platform output on Raspbian testing/jessie ~May 2014:
	# Linux-3.10.25+-armv6l-with-debian-7.4
	if plat.lower().find('armv6l-with-debian') > -1:
		return RASPBERRY_PI
	# Handle pidora distribution.
	elif plat.lower().find('raspberry_pi') > -1:
		return RASPBERRY_PI
	# Handle Beaglebone Black
	# Platform output on Debian ~May 2014:
	# Linux-3.8.13-bone47-armv7l-with-debian-7.4
	elif plat.lower().find('armv7l-with-debian') > -1:
		return BEAGLEBONE_BLACK
	# Handle Beaglebone Black
	# Platform output on Ubuntu ~July 2014:
	# Linux-3.8.13-bone56-armv7l-with-Ubuntu-14.04-trusty
	elif plat.lower().find('armv7l-with-ubuntu') > -1:
		return BEAGLEBONE_BLACK	
	else:
		return UNKNOWN

def pi_revision():
	"""Detect the revision number of a Raspberry Pi, useful for changing
	functionality like default I2C bus based on revision."""
	# Revision list available at: http://elinux.org/RPi_HardwareHistory#Board_Revision_History
	with open('/proc/cpuinfo', 'r') as infile:
		for line in infile:
			# Match a line of the form "Revision : 0002" while ignoring extra
			# info in front of the revsion (like 1000 when the Pi was over-volted).
			match = re.match('Revision\s+:\s+.*(\w{4})$', line)
			if match and match.group(1) in ['0002', '0003']:
				# Return revision 1 if revision ends with 0002 or 0003.
				return 1
			elif match:
				# Assume revision 2 if revision ends with any other 4 chars.
				return 2
		# Couldn't find the revision, throw an exception.
		raise RuntimeError('Could not determine Raspberry Pi revision.')