linux/drivers/rtc/systohc.c
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   1/*
   2 * This program is free software; you can redistribute it and/or modify it
   3 * under the terms of the GNU General Public License version 2 as published by
   4 * the Free Software Foundation.
   5 *
   6 */
   7#include <linux/rtc.h>
   8#include <linux/time.h>
   9
  10/**
  11 * rtc_set_ntp_time - Save NTP synchronized time to the RTC
  12 * @now: Current time of day
  13 *
  14 * Replacement for the NTP platform function update_persistent_clock
  15 * that stores time for later retrieval by rtc_hctosys.
  16 *
  17 * Returns 0 on successful RTC update, -ENODEV if a RTC update is not
  18 * possible at all, and various other -errno for specific temporary failure
  19 * cases.
  20 *
  21 * If temporary failure is indicated the caller should try again 'soon'
  22 */
  23int rtc_set_ntp_time(struct timespec now)
  24{
  25        struct rtc_device *rtc;
  26        struct rtc_time tm;
  27        int err = -ENODEV;
  28
  29        if (now.tv_nsec < (NSEC_PER_SEC >> 1))
  30                rtc_time_to_tm(now.tv_sec, &tm);
  31        else
  32                rtc_time_to_tm(now.tv_sec + 1, &tm);
  33
  34        rtc = rtc_class_open(CONFIG_RTC_HCTOSYS_DEVICE);
  35        if (rtc) {
  36                /* rtc_hctosys exclusively uses UTC, so we call set_time here,
  37                 * not set_mmss. */
  38                if (rtc->ops && (rtc->ops->set_time || rtc->ops->set_mmss))
  39                        err = rtc_set_time(rtc, &tm);
  40                rtc_class_close(rtc);
  41        }
  42
  43        return err;
  44}
  45
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