# Copyright (c) 2010 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.
|
|
"""Provides utility methods for the Real Time Clock device.
|
"""
|
|
import errno, glob, os
|
|
|
def get_rtc_devices():
|
"""
|
Return a list of all RTC device names on the system.
|
|
The RTC device node will be found at /dev/$NAME.
|
"""
|
return [os.path.basename(rtc) for rtc in glob.glob('/sys/class/rtc/*')]
|
|
|
def get_seconds(utc=True, rtc_device='rtc0'):
|
"""
|
Read the current time out of the RTC
|
"""
|
return int(file('/sys/class/rtc/%s/since_epoch' % rtc_device).readline())
|
|
|
def write_wake_alarm(alarm_time, rtc_device='rtc0'):
|
"""
|
Write a value to the wake alarm
|
"""
|
f = file('/sys/class/rtc/%s/wakealarm' % rtc_device, 'w')
|
f.write('%s\n' % str(alarm_time))
|
f.close()
|
|
|
def set_wake_alarm(alarm_time, rtc_device='rtc0'):
|
"""
|
Set the hardware RTC-based wake alarm to 'alarm_time'.
|
"""
|
try:
|
write_wake_alarm(alarm_time, rtc_device)
|
except IOError as (errnum, strerror):
|
if errnum != errno.EBUSY:
|
raise
|
write_wake_alarm('clear', rtc_device)
|
write_wake_alarm(alarm_time, rtc_device)
|
