Omnia: Add SFP insert/remove handler daemon

Omnia has GPIO expander that generates IRQs when the SFP is inserted or
removed.

mvneta driver in Omnia kernel is hacked to export attribute that sets
the target PHY. Catch is that interface has to be restarted after a switch
of the target PHY has happened.

This daemon connects this together: It waits for IRQ (in fact for GPIO
change) and performs the PHY switch and restart of network.

This is only a temporary solution for the meantime between Omnia release
and phylink driver adoption.

sfpswitch/sfpswitch.py

+#!/usr/bin/python
+
+import sys
+import os
+import select
+
+sfpdet_pin = 508
+sfpdis_pin = 505
+
+gpio_export = '/sys/class/gpio/export'
+sfp_select = '/sys/devices/platform/soc/soc:internal-regs/f1034000.ethernet/net/eth1/phy_select'
+map = { 1: 'phy-def', 0: 'phy-sfp' }
+cmd_net_res = '/etc/init.d/network restart'
+
+def write_once(path, value):
+	with open(path, 'w') as f:
+		f.write(value)
+
+
+
+def gpio_dir(pin):
+	return '/sys/class/gpio/gpio%d/' % pin
+
+def init_gpio(pin):
+	if not (os.path.exists(gpio_dir(pin)) and
+		os.path.isdir(gpio_dir(pin))):
+		write_once(gpio_export, str(pin))
+
+	if not (os.path.exists(gpio_dir(pin)) and
+		os.path.isdir(gpio_dir(pin))):
+		raise Exception('Can not access %s' % gpio_dir(pin))
+	
+
+def init():
+	init_gpio(sfpdet_pin)
+	init_gpio(sfpdis_pin)
+
+	write_once(os.path.join(gpio_dir(sfpdet_pin), 'direction'), 'in')
+	write_once(os.path.join(gpio_dir(sfpdet_pin), 'edge'), 'both')
+
+	write_once(os.path.join(gpio_dir(sfpdis_pin), 'direction'), 'out')
+	write_once(os.path.join(gpio_dir(sfpdis_pin), 'value'), '0')
+
+
+
+def do_switch(state, restart_net=True):
+	print 'Switching state to %s' % map[state]
+	write_once(sfp_select, map[state])
+	if restart_net:
+		os.system(cmd_net_res)
+
+
+def oneshot():
+	init()
+	f = open(os.path.join(gpio_dir(sfpdet_pin), 'value'), 'r')
+	state_last = int(f.read().strip())
+	do_switch(state_last, False)
+
+
+def run():
+	init()
+
+	f = open(os.path.join(gpio_dir(sfpdet_pin), 'value'), 'r')
+	po = select.poll()
+	po.register(f, select.POLLPRI)
+
+	state_last = int(f.read().strip())
+	do_switch(state_last)
+
+	while 1:
+		events = po.poll(60000)
+		if events:
+			f.seek(0)
+			state = int(f.read().strip())
+			if state != state_last:
+				state_last = state
+				do_switch(state)
+
+def create_daemon():
+	try:
+		pid = os.fork()
+		if pid > 0:
+			print 'PID: %d' % pid
+			os._exit(0)
+
+	except OSError, error:
+		print 'Unable to fork. Error: %d (%s)' % (error.errno, error.strerror)
+		os._exit(1)
+
+	run()
+
+def help():
+	print """sfpswitch.py daemon for Turris Omnia
+
+--oneshot : set the PHY and restart network, then exit
+--nodaemon : run in foreground
+NO PARAM : daemonize and wait for PHY change
+"""
+
+def main():
+	if len(sys.argv) > 1:
+		if sys.argv[1] == '--oneshot':
+			oneshot()
+		elif sys.argv[1] == '--nodaemon':
+			run()
+		elif sys.argv[1] == '--help':
+			help()
+		else:
+			print "Unknown option: %s" % sys.argv[1]
+			help()
+	else:
+		create_daemon()
+
+if __name__ == '__main__':
+	main()
+