/*
   * This program is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 as published by
   * the Free Software Foundation.
   *
   */
  #include <linux/rtc.h>
  #include <linux/time.h>
  
  /**
   * rtc_set_ntp_time - Save NTP synchronized time to the RTC
   * @now: Current time of day
   *
   * Replacement for the NTP platform function update_persistent_clock
   * that stores time for later retrieval by rtc_hctosys.
   *
   * Returns 0 on successful RTC update, -ENODEV if a RTC update is not
   * possible at all, and various other -errno for specific temporary failure
   * cases.
   *
   * If temporary failure is indicated the caller should try again 'soon'
   */
  int rtc_set_ntp_time(struct timespec now)
  {
  	struct rtc_device *rtc;
  	struct rtc_time tm;
  	int err = -ENODEV;
  
  	if (now.tv_nsec < (NSEC_PER_SEC >> 1))
  		rtc_time_to_tm(now.tv_sec, &tm);
  	else
  		rtc_time_to_tm(now.tv_sec + 1, &tm);
  
  	rtc = rtc_class_open(CONFIG_RTC_HCTOSYS_DEVICE);
  	if (rtc) {
  		/* rtc_hctosys exclusively uses UTC, so we call set_time here,
  		 * not set_mmss. */
  		if (rtc->ops && (rtc->ops->set_time || rtc->ops->set_mmss))
  			err = rtc_set_time(rtc, &tm);
  		rtc_class_close(rtc);
  	}
  
  	return err;
  }