1 # Copyright (c) 2010 The Chromium OS Authors. All rights reserved. 2 # Use of this source code is governed by a BSD-style license that can 3 # be # found in the LICENSE file. 4 5 """Provides utility methods for the Real Time Clock device. 6 """ 7 8 import errno, glob, os 9 10 11 def get_rtc_devices(): 12 """ 13 Return a list of all RTC device names on the system. 14 15 The RTC device node will be found at /dev/$NAME. 16 """ 17 return [os.path.basename(rtc) for rtc in glob.glob('/sys/class/rtc/*')] 18 19 20 def get_seconds(utc=True, rtc_device='rtc0'): 21 """ 22 Read the current time out of the RTC 23 """ 24 return int(file('/sys/class/rtc/%s/since_epoch' % rtc_device).readline()) 25 26 27 def write_wake_alarm(alarm_time, rtc_device='rtc0'): 28 """ 29 Write a value to the wake alarm 30 """ 31 f = file('/sys/class/rtc/%s/wakealarm' % rtc_device, 'w') 32 f.write('%s\n' % str(alarm_time)) 33 f.close() 34 35 36 def set_wake_alarm(alarm_time, rtc_device='rtc0'): 37 """ 38 Set the hardware RTC-based wake alarm to 'alarm_time'. 39 """ 40 try: 41 write_wake_alarm(alarm_time, rtc_device) 42 except IOError as (errnum, strerror): 43 if errnum != errno.EBUSY: 44 raise 45 write_wake_alarm('clear', rtc_device) 46 write_wake_alarm(alarm_time, rtc_device) 47
