diff options
| -rw-r--r-- | kernel/time/timekeeping.c | 58 |
1 files changed, 51 insertions, 7 deletions
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 9a0bc98fbe1d..0355f125d585 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -788,22 +788,66 @@ void timekeeping_inject_sleeptime(struct timespec *delta) static void timekeeping_resume(void) { struct timekeeper *tk = &timekeeper; + struct clocksource *clock = tk->clock; unsigned long flags; - struct timespec ts; + struct timespec ts_new, ts_delta; + cycle_t cycle_now, cycle_delta; + bool suspendtime_found = false; - read_persistent_clock(&ts); + read_persistent_clock(&ts_new); clockevents_resume(); clocksource_resume(); write_seqlock_irqsave(&tk->lock, flags); - if (timespec_compare(&ts, &timekeeping_suspend_time) > 0) { - ts = timespec_sub(ts, timekeeping_suspend_time); - __timekeeping_inject_sleeptime(tk, &ts); + /* + * After system resumes, we need to calculate the suspended time and + * compensate it for the OS time. There are 3 sources that could be + * used: Nonstop clocksource during suspend, persistent clock and rtc + * device. + * + * One specific platform may have 1 or 2 or all of them, and the + * preference will be: + * suspend-nonstop clocksource -> persistent clock -> rtc + * The less preferred source will only be tried if there is no better + * usable source. The rtc part is handled separately in rtc core code. + */ + cycle_now = clock->read(clock); + if ((clock->flags & CLOCK_SOURCE_SUSPEND_NONSTOP) && + cycle_now > clock->cycle_last) { + u64 num, max = ULLONG_MAX; + u32 mult = clock->mult; + u32 shift = clock->shift; + s64 nsec = 0; + + cycle_delta = (cycle_now - clock->cycle_last) & clock->mask; + + /* + * "cycle_delta * mutl" may cause 64 bits overflow, if the + * suspended time is too long. In that case we need do the + * 64 bits math carefully + */ + do_div(max, mult); + if (cycle_delta > max) { + num = div64_u64(cycle_delta, max); + nsec = (((u64) max * mult) >> shift) * num; + cycle_delta -= num * max; + } + nsec += ((u64) cycle_delta * mult) >> shift; + + ts_delta = ns_to_timespec(nsec); + suspendtime_found = true; + } else if (timespec_compare(&ts_new, &timekeeping_suspend_time) > 0) { + ts_delta = timespec_sub(ts_new, timekeeping_suspend_time); + suspendtime_found = true; } - /* re-base the last cycle value */ - tk->clock->cycle_last = tk->clock->read(tk->clock); + + if (suspendtime_found) + __timekeeping_inject_sleeptime(tk, &ts_delta); + + /* Re-base the last cycle value */ + clock->cycle_last = cycle_now; tk->ntp_error = 0; timekeeping_suspended = 0; timekeeping_update(tk, false); |