/* * 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 * @target_nsec: pointer for desired now->tv_nsec value * * Replacement for the NTP platform function update_persistent_clock64 * 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. * * -EPROTO is returned if now.tv_nsec is not close enough to *target_nsec. * * If temporary failure is indicated the caller should try again 'soon' */ int rtc_set_ntp_time(struct timespec64 now, unsigned long *target_nsec) { struct rtc_device *rtc; struct rtc_time tm; struct timespec64 to_set; int err = -ENODEV; bool ok; rtc = rtc_class_open(CONFIG_RTC_SYSTOHC_DEVICE); if (!rtc) goto out_err; if (!rtc->ops || (!rtc->ops->set_time && !rtc->ops->set_mmss64 && !rtc->ops->set_mmss)) goto out_close; /* Compute the value of tv_nsec we require the caller to supply in * now.tv_nsec. This is the value such that (now + * set_offset_nsec).tv_nsec == 0. */ set_normalized_timespec64(&to_set, 0, -rtc->set_offset_nsec); *target_nsec = to_set.tv_nsec; /* The ntp code must call this with the correct value in tv_nsec, if * it does not we update target_nsec and return EPROTO to make the ntp * code try again later. */ ok = rtc_tv_nsec_ok(rtc->set_offset_nsec, &to_set, &now); if (!ok) { err = -EPROTO; goto out_close; } rtc_time64_to_tm(to_set.tv_sec, &tm); /* rtc_hctosys exclusively uses UTC, so we call set_time here, not * set_mmss. */ err = rtc_set_time(rtc, &tm); out_close: rtc_class_close(rtc); out_err: return err; }