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#!/usr/bin/env python
#
# gpsd.hotplug -- hotplug script for gpsd
#
# This script will tell a running gpsd that it should look at the
# device that just went active, because it might be a GPS.
#
# This script is part of the gpsd distrbution: see http://gpsd.berlios.de
# Written by Eric S. Raymond, March 2005.
import os, syslog, glob, socket
def gpsd_connect():
"Acquire a connection to the GPSD port."
msg = "getaddrinfo returns an empty list"
sock = None
sockfile = None
for res in socket.getaddrinfo("localhost", 2947, 0, socket.SOCK_STREAM):
(af, socktype, proto, canonname, sa) = res
try:
sock = socket.socket(af, socktype, proto)
sock.connect(sa)
sockfile = sock.makefile()
except socket.error, msg:
if sock:
sock.close()
sock = None
sockfile = None
continue
break
if not sock:
syslog.syslog("gpsd is not running or is unreachable")
return None
else:
return sockfile
def wake_up_gpsd(devpath):
# First, discover the device
subnodes = glob.glob("/sys" + devpath + "/*")
subnodes = map(os.path.basename, subnodes)
subnodes = filter(lambda s: s.startswith("ttyUSB"), subnodes)
if len(subnodes) == 0:
syslog.syslog("no ttyUSB device under " + devpath)
return
elif len(subnodes) > 1:
syslog.syslog("too many ttyUSB devices under " + devpath)
return
else:
tty = "/dev/" + subnodes[0]
syslog.syslog(tty + " has gone active")
# Next get a connection to gpsd; start one if not already running
connect = gpsd_connect()
if connect:
syslog.syslog("reached a running gpsd")
else:
syslog.syslog("attempting to launch gpsd")
os.system("/etc/init.d/gpsd start")
connect = gpsd_connect()
if not connect:
return
# We've got a live connection to gpsd. Ship it the right F command.
# No need to look at the response; gpsd will lock on to the device
# if it's really a GPS and ignore it if it's not.
connect.write("F=%s\r\n" % tty)
connect.close()
return
# GPSes don't have their own USB device class. They're serial-over-USB
# devices, so what you see is actually the ID of the serial-over-USB chip.
# Fortunately, just two of these account for over 80% of consumer-grade
# GPS sensors.
#
# The Prolific Technology 2303 (commonly in tandem with SiRF chips)
# FTDI 8U232AM
# Cypress M8/CY7C64013 (DeLorme uses these)
supported_products = ("67B/2303", "403/6001", "1163/100")
if __name__ == '__main__':
action = os.getenv("ACTION")
devpath = os.getenv("DEVPATH")
product = os.getenv("PRODUCT")
syslog.openlog('gpsdplug', 0, syslog.LOG_DAEMON)
syslog.syslog("gpsdplug begins with action %s" % action)
syslog.syslog("PRODUCT = %s, DEVPATH = %s" % (product, devpath))
if not devpath or not action:
pass
elif not filter(lambda x: product.startswith(x + "/"), supported_products):
pass
elif action == "add":
wake_up_gpsd(devpath)
syslog.syslog("gpsdplug ends")
syslog.closelog()
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