return leap;
}
+#if defined(CONFIG_GENERIC_CMOS_UPDATE) || defined(CONFIG_RTC_SYSTOHC)
static void sync_hw_clock(struct work_struct *work);
-static DECLARE_DELAYED_WORK(sync_work, sync_hw_clock);
-
-static void sched_sync_hw_clock(struct timespec64 now,
- unsigned long target_nsec, bool fail)
+static DECLARE_WORK(sync_work, sync_hw_clock);
+static struct hrtimer sync_hrtimer;
+#define SYNC_PERIOD_NS (11UL * 60 * NSEC_PER_SEC)
+static enum hrtimer_restart sync_timer_callback(struct hrtimer *timer)
{
- struct timespec64 next;
-
- ktime_get_real_ts64(&next);
- if (!fail)
- next.tv_sec = 659;
- else {
- /*
- * Try again as soon as possible. Delaying long periods
- * decreases the accuracy of the work queue timer. Due to this
- * the algorithm is very likely to require a short-sleep retry
- * after the above long sleep to synchronize ts_nsec.
- */
- next.tv_sec = 0;
- }
-
- /* Compute the needed delay that will get to tv_nsec == target_nsec */
- next.tv_nsec = target_nsec - next.tv_nsec;
- if (next.tv_nsec <= 0)
- next.tv_nsec += NSEC_PER_SEC;
- if (next.tv_nsec >= NSEC_PER_SEC) {
- next.tv_sec++;
- next.tv_nsec -= NSEC_PER_SEC;
- }
+ queue_work(system_power_efficient_wq, &sync_work);
- queue_delayed_work(system_power_efficient_wq, &sync_work,
- timespec64_to_jiffies(&next));
+ return HRTIMER_NORESTART;
}
-static void sync_rtc_clock(void)
+static void sched_sync_hw_clock(unsigned long offset_nsec, bool retry)
{
- unsigned long target_nsec;
- struct timespec64 adjust, now;
- int rc;
+ ktime_t exp = ktime_set(ktime_get_real_seconds(), 0);
- if (!IS_ENABLED(CONFIG_RTC_SYSTOHC))
- return;
+ if (retry)
+ exp = ktime_add_ns(exp, 2 * NSEC_PER_SEC - offset_nsec);
+ else
+ exp = ktime_add_ns(exp, SYNC_PERIOD_NS - offset_nsec);
- ktime_get_real_ts64(&now);
+ hrtimer_start(&sync_hrtimer, exp, HRTIMER_MODE_ABS);
+}
- adjust = now;
- if (persistent_clock_is_local)
- adjust.tv_sec -= (sys_tz.tz_minuteswest * 60);
+/*
+ * Check whether @now is correct versus the required time to update the RTC
+ * and calculate the value which needs to be written to the RTC so that the
+ * next seconds increment of the RTC after the write is aligned with the next
+ * seconds increment of clock REALTIME.
+ *
+ * tsched t1 write(t2.tv_sec - 1sec)) t2 RTC increments seconds
+ *
+ * t2.tv_nsec == 0
+ * tsched = t2 - set_offset_nsec
+ * newval = t2 - NSEC_PER_SEC
+ *
+ * ==> neval = tsched + set_offset_nsec - NSEC_PER_SEC
+ *
+ * As the execution of this code is not guaranteed to happen exactly at
+ * tsched this allows it to happen within a fuzzy region:
+ *
+ * abs(now - tsched) < FUZZ
+ *
+ * If @now is not inside the allowed window the function returns false.
+ */
+static inline bool rtc_tv_nsec_ok(unsigned long set_offset_nsec,
+ struct timespec64 *to_set,
+ const struct timespec64 *now)
+{
+ /* Allowed error in tv_nsec, arbitarily set to 5 jiffies in ns. */
+ const unsigned long TIME_SET_NSEC_FUZZ = TICK_NSEC * 5;
+ struct timespec64 delay = {.tv_sec = -1,
+ .tv_nsec = set_offset_nsec};
- /*
- * The current RTC in use will provide the target_nsec it wants to be
- * called at, and does rtc_tv_nsec_ok internally.
- */
- rc = rtc_set_ntp_time(adjust, &target_nsec);
- if (rc == -ENODEV)
- return;
+ *to_set = timespec64_add(*now, delay);
+
+ if (to_set->tv_nsec < TIME_SET_NSEC_FUZZ) {
+ to_set->tv_nsec = 0;
+ return true;
+ }
- sched_sync_hw_clock(now, target_nsec, rc);
+ if (to_set->tv_nsec > NSEC_PER_SEC - TIME_SET_NSEC_FUZZ) {
+ to_set->tv_sec++;
+ to_set->tv_nsec = 0;
+ return true;
+ }
+ return false;
}
#ifdef CONFIG_GENERIC_CMOS_UPDATE
{
return -ENODEV;
}
+#else
+static inline int update_persistent_clock64(struct timespec64 now64)
+{
+ return -ENODEV;
+}
#endif
-static bool sync_cmos_clock(void)
+#ifdef CONFIG_RTC_SYSTOHC
+/* Save NTP synchronized time to the RTC */
+static int update_rtc(struct timespec64 *to_set, unsigned long *offset_nsec)
{
- static bool no_cmos;
- struct timespec64 now;
- struct timespec64 adjust;
- int rc = -EPROTO;
- long target_nsec = NSEC_PER_SEC / 2;
+ struct rtc_device *rtc;
+ struct rtc_time tm;
+ int err = -ENODEV;
- if (!IS_ENABLED(CONFIG_GENERIC_CMOS_UPDATE))
- return false;
+ rtc = rtc_class_open(CONFIG_RTC_SYSTOHC_DEVICE);
+ if (!rtc)
+ return -ENODEV;
- if (no_cmos)
- return false;
+ if (!rtc->ops || !rtc->ops->set_time)
+ goto out_close;
- /*
- * Historically update_persistent_clock64() has followed x86
- * semantics, which match the MC146818A/etc RTC. This RTC will store
- * 'adjust' and then in .5s it will advance once second.
- *
- * Architectures are strongly encouraged to use rtclib and not
- * implement this legacy API.
- */
- ktime_get_real_ts64(&now);
- if (rtc_tv_nsec_ok(-1 * target_nsec, &adjust, &now)) {
- if (persistent_clock_is_local)
- adjust.tv_sec -= (sys_tz.tz_minuteswest * 60);
- rc = update_persistent_clock64(adjust);
- /*
- * The machine does not support update_persistent_clock64 even
- * though it defines CONFIG_GENERIC_CMOS_UPDATE.
- */
- if (rc == -ENODEV) {
- no_cmos = true;
- return false;
- }
+ /* First call might not have the correct offset */
+ if (*offset_nsec == rtc->set_offset_nsec) {
+ rtc_time64_to_tm(to_set->tv_sec, &tm);
+ err = rtc_set_time(rtc, &tm);
+ } else {
+ /* Store the update offset and let the caller try again */
+ *offset_nsec = rtc->set_offset_nsec;
+ err = -EAGAIN;
}
-
- sched_sync_hw_clock(now, target_nsec, rc);
- return true;
+out_close:
+ rtc_class_close(rtc);
+ return err;
+}
+#else
+static inline int update_rtc(struct timespec64 *to_set, unsigned long *offset_nsec)
+{
+ return -ENODEV;
}
+#endif
/*
* If we have an externally synchronized Linux clock, then update RTC clock
*/
static void sync_hw_clock(struct work_struct *work)
{
- if (!ntp_synced())
- return;
+ /*
+ * The default synchronization offset is 500ms for the deprecated
+ * update_persistent_clock64() under the assumption that it uses
+ * the infamous CMOS clock (MC146818).
+ */
+ static unsigned long offset_nsec = NSEC_PER_SEC / 2;
+ struct timespec64 now, to_set;
+ int res = -EAGAIN;
- if (sync_cmos_clock())
+ /*
+ * Don't update if STA_UNSYNC is set and if ntp_notify_cmos_timer()
+ * managed to schedule the work between the timer firing and the
+ * work being able to rearm the timer. Wait for the timer to expire.
+ */
+ if (!ntp_synced() || hrtimer_is_queued(&sync_hrtimer))
return;
- sync_rtc_clock();
+ ktime_get_real_ts64(&now);
+ /* If @now is not in the allowed window, try again */
+ if (!rtc_tv_nsec_ok(offset_nsec, &to_set, &now))
+ goto rearm;
+
+ /* Take timezone adjusted RTCs into account */
+ if (persistent_clock_is_local)
+ to_set.tv_sec -= (sys_tz.tz_minuteswest * 60);
+
+ /* Try the legacy RTC first. */
+ res = update_persistent_clock64(to_set);
+ if (res != -ENODEV)
+ goto rearm;
+
+ /* Try the RTC class */
+ res = update_rtc(&to_set, &offset_nsec);
+ if (res == -ENODEV)
+ return;
+rearm:
+ sched_sync_hw_clock(offset_nsec, res != 0);
}
void ntp_notify_cmos_timer(void)
{
- if (!ntp_synced())
- return;
+ /*
+ * When the work is currently executed but has not yet the timer
+ * rearmed this queues the work immediately again. No big issue,
+ * just a pointless work scheduled.
+ */
+ if (ntp_synced() && !hrtimer_is_queued(&sync_hrtimer))
+ queue_work(system_power_efficient_wq, &sync_work);
+}
- if (IS_ENABLED(CONFIG_GENERIC_CMOS_UPDATE) ||
- IS_ENABLED(CONFIG_RTC_SYSTOHC))
- queue_delayed_work(system_power_efficient_wq, &sync_work, 0);
+static void __init ntp_init_cmos_sync(void)
+{
+ hrtimer_init(&sync_hrtimer, CLOCK_REALTIME, HRTIMER_MODE_ABS);
+ sync_hrtimer.function = sync_timer_callback;
}
+#else /* CONFIG_GENERIC_CMOS_UPDATE) || defined(CONFIG_RTC_SYSTOHC) */
+static inline void __init ntp_init_cmos_sync(void) { }
+#endif /* !CONFIG_GENERIC_CMOS_UPDATE) || defined(CONFIG_RTC_SYSTOHC) */
/*
* Propagate a new txc->status value into the NTP state:
void __init ntp_init(void)
{
ntp_clear();
+ ntp_init_cmos_sync();
}
projects / linux-2.6-microblaze.git / blobdiff