![Richard Cochran](/assets/img/avatar_default.png)
Fix a few minor newline issues. Signed-off-by: Richard Cochran <richardcochran@gmail.com> Signed-off-by: John Stultz <john.stultz@linaro.org>
1277 lines
34 KiB
C
1277 lines
34 KiB
C
/*
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* linux/kernel/time/timekeeping.c
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*
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* Kernel timekeeping code and accessor functions
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*
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* This code was moved from linux/kernel/timer.c.
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* Please see that file for copyright and history logs.
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*
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*/
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#include <linux/module.h>
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#include <linux/interrupt.h>
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#include <linux/percpu.h>
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#include <linux/init.h>
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#include <linux/mm.h>
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#include <linux/sched.h>
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#include <linux/syscore_ops.h>
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#include <linux/clocksource.h>
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#include <linux/jiffies.h>
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#include <linux/time.h>
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#include <linux/tick.h>
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#include <linux/stop_machine.h>
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/* Structure holding internal timekeeping values. */
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struct timekeeper {
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/* Current clocksource used for timekeeping. */
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struct clocksource *clock;
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/* NTP adjusted clock multiplier */
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u32 mult;
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/* The shift value of the current clocksource. */
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int shift;
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/* Number of clock cycles in one NTP interval. */
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cycle_t cycle_interval;
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/* Number of clock shifted nano seconds in one NTP interval. */
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u64 xtime_interval;
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/* shifted nano seconds left over when rounding cycle_interval */
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s64 xtime_remainder;
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/* Raw nano seconds accumulated per NTP interval. */
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u32 raw_interval;
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/* Clock shifted nano seconds remainder not stored in xtime.tv_nsec. */
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u64 xtime_nsec;
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/* Difference between accumulated time and NTP time in ntp
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* shifted nano seconds. */
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s64 ntp_error;
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/* Shift conversion between clock shifted nano seconds and
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* ntp shifted nano seconds. */
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int ntp_error_shift;
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/* The current time */
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struct timespec xtime;
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/*
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* wall_to_monotonic is what we need to add to xtime (or xtime corrected
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* for sub jiffie times) to get to monotonic time. Monotonic is pegged
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* at zero at system boot time, so wall_to_monotonic will be negative,
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* however, we will ALWAYS keep the tv_nsec part positive so we can use
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* the usual normalization.
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*
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* wall_to_monotonic is moved after resume from suspend for the
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* monotonic time not to jump. We need to add total_sleep_time to
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* wall_to_monotonic to get the real boot based time offset.
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*
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* - wall_to_monotonic is no longer the boot time, getboottime must be
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* used instead.
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*/
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struct timespec wall_to_monotonic;
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/* time spent in suspend */
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struct timespec total_sleep_time;
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/* The raw monotonic time for the CLOCK_MONOTONIC_RAW posix clock. */
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struct timespec raw_time;
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/* Seqlock for all timekeeper values */
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seqlock_t lock;
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};
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static struct timekeeper timekeeper;
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/*
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* This read-write spinlock protects us from races in SMP while
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* playing with xtime.
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*/
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__cacheline_aligned_in_smp DEFINE_SEQLOCK(xtime_lock);
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/* flag for if timekeeping is suspended */
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int __read_mostly timekeeping_suspended;
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/**
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* timekeeper_setup_internals - Set up internals to use clocksource clock.
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*
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* @clock: Pointer to clocksource.
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*
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* Calculates a fixed cycle/nsec interval for a given clocksource/adjustment
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* pair and interval request.
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*
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* Unless you're the timekeeping code, you should not be using this!
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*/
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static void timekeeper_setup_internals(struct clocksource *clock)
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{
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cycle_t interval;
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u64 tmp, ntpinterval;
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timekeeper.clock = clock;
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clock->cycle_last = clock->read(clock);
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/* Do the ns -> cycle conversion first, using original mult */
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tmp = NTP_INTERVAL_LENGTH;
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tmp <<= clock->shift;
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ntpinterval = tmp;
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tmp += clock->mult/2;
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do_div(tmp, clock->mult);
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if (tmp == 0)
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tmp = 1;
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interval = (cycle_t) tmp;
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timekeeper.cycle_interval = interval;
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/* Go back from cycles -> shifted ns */
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timekeeper.xtime_interval = (u64) interval * clock->mult;
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timekeeper.xtime_remainder = ntpinterval - timekeeper.xtime_interval;
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timekeeper.raw_interval =
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((u64) interval * clock->mult) >> clock->shift;
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timekeeper.xtime_nsec = 0;
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timekeeper.shift = clock->shift;
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timekeeper.ntp_error = 0;
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timekeeper.ntp_error_shift = NTP_SCALE_SHIFT - clock->shift;
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/*
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* The timekeeper keeps its own mult values for the currently
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* active clocksource. These value will be adjusted via NTP
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* to counteract clock drifting.
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*/
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timekeeper.mult = clock->mult;
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}
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/* Timekeeper helper functions. */
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static inline s64 timekeeping_get_ns(void)
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{
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cycle_t cycle_now, cycle_delta;
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struct clocksource *clock;
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/* read clocksource: */
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clock = timekeeper.clock;
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cycle_now = clock->read(clock);
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/* calculate the delta since the last update_wall_time: */
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cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
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/* return delta convert to nanoseconds using ntp adjusted mult. */
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return clocksource_cyc2ns(cycle_delta, timekeeper.mult,
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timekeeper.shift);
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}
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static inline s64 timekeeping_get_ns_raw(void)
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{
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cycle_t cycle_now, cycle_delta;
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struct clocksource *clock;
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/* read clocksource: */
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clock = timekeeper.clock;
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cycle_now = clock->read(clock);
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/* calculate the delta since the last update_wall_time: */
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cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
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/* return delta convert to nanoseconds. */
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return clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift);
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}
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/* must hold write on timekeeper.lock */
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static void timekeeping_update(bool clearntp)
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{
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if (clearntp) {
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timekeeper.ntp_error = 0;
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ntp_clear();
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}
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update_vsyscall(&timekeeper.xtime, &timekeeper.wall_to_monotonic,
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timekeeper.clock, timekeeper.mult);
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}
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/**
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* timekeeping_forward_now - update clock to the current time
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*
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* Forward the current clock to update its state since the last call to
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* update_wall_time(). This is useful before significant clock changes,
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* as it avoids having to deal with this time offset explicitly.
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*/
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static void timekeeping_forward_now(void)
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{
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cycle_t cycle_now, cycle_delta;
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struct clocksource *clock;
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s64 nsec;
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clock = timekeeper.clock;
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cycle_now = clock->read(clock);
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cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
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clock->cycle_last = cycle_now;
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nsec = clocksource_cyc2ns(cycle_delta, timekeeper.mult,
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timekeeper.shift);
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/* If arch requires, add in gettimeoffset() */
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nsec += arch_gettimeoffset();
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timespec_add_ns(&timekeeper.xtime, nsec);
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nsec = clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift);
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timespec_add_ns(&timekeeper.raw_time, nsec);
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}
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/**
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* getnstimeofday - Returns the time of day in a timespec
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* @ts: pointer to the timespec to be set
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*
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* Returns the time of day in a timespec.
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*/
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void getnstimeofday(struct timespec *ts)
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{
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unsigned long seq;
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s64 nsecs;
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WARN_ON(timekeeping_suspended);
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do {
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seq = read_seqbegin(&timekeeper.lock);
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*ts = timekeeper.xtime;
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nsecs = timekeeping_get_ns();
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/* If arch requires, add in gettimeoffset() */
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nsecs += arch_gettimeoffset();
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} while (read_seqretry(&timekeeper.lock, seq));
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timespec_add_ns(ts, nsecs);
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}
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EXPORT_SYMBOL(getnstimeofday);
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ktime_t ktime_get(void)
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{
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unsigned int seq;
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s64 secs, nsecs;
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WARN_ON(timekeeping_suspended);
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do {
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seq = read_seqbegin(&timekeeper.lock);
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secs = timekeeper.xtime.tv_sec +
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timekeeper.wall_to_monotonic.tv_sec;
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nsecs = timekeeper.xtime.tv_nsec +
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timekeeper.wall_to_monotonic.tv_nsec;
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nsecs += timekeeping_get_ns();
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/* If arch requires, add in gettimeoffset() */
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nsecs += arch_gettimeoffset();
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} while (read_seqretry(&timekeeper.lock, seq));
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/*
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* Use ktime_set/ktime_add_ns to create a proper ktime on
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* 32-bit architectures without CONFIG_KTIME_SCALAR.
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*/
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return ktime_add_ns(ktime_set(secs, 0), nsecs);
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}
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EXPORT_SYMBOL_GPL(ktime_get);
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/**
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* ktime_get_ts - get the monotonic clock in timespec format
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* @ts: pointer to timespec variable
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*
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* The function calculates the monotonic clock from the realtime
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* clock and the wall_to_monotonic offset and stores the result
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* in normalized timespec format in the variable pointed to by @ts.
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*/
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void ktime_get_ts(struct timespec *ts)
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{
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struct timespec tomono;
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unsigned int seq;
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s64 nsecs;
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WARN_ON(timekeeping_suspended);
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do {
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seq = read_seqbegin(&timekeeper.lock);
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*ts = timekeeper.xtime;
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tomono = timekeeper.wall_to_monotonic;
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nsecs = timekeeping_get_ns();
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/* If arch requires, add in gettimeoffset() */
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nsecs += arch_gettimeoffset();
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} while (read_seqretry(&timekeeper.lock, seq));
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set_normalized_timespec(ts, ts->tv_sec + tomono.tv_sec,
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ts->tv_nsec + tomono.tv_nsec + nsecs);
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}
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EXPORT_SYMBOL_GPL(ktime_get_ts);
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#ifdef CONFIG_NTP_PPS
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/**
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* getnstime_raw_and_real - get day and raw monotonic time in timespec format
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* @ts_raw: pointer to the timespec to be set to raw monotonic time
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* @ts_real: pointer to the timespec to be set to the time of day
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*
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* This function reads both the time of day and raw monotonic time at the
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* same time atomically and stores the resulting timestamps in timespec
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* format.
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*/
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void getnstime_raw_and_real(struct timespec *ts_raw, struct timespec *ts_real)
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{
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unsigned long seq;
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s64 nsecs_raw, nsecs_real;
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WARN_ON_ONCE(timekeeping_suspended);
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do {
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u32 arch_offset;
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seq = read_seqbegin(&timekeeper.lock);
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*ts_raw = timekeeper.raw_time;
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*ts_real = timekeeper.xtime;
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nsecs_raw = timekeeping_get_ns_raw();
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nsecs_real = timekeeping_get_ns();
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/* If arch requires, add in gettimeoffset() */
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arch_offset = arch_gettimeoffset();
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nsecs_raw += arch_offset;
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nsecs_real += arch_offset;
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} while (read_seqretry(&timekeeper.lock, seq));
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timespec_add_ns(ts_raw, nsecs_raw);
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timespec_add_ns(ts_real, nsecs_real);
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}
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EXPORT_SYMBOL(getnstime_raw_and_real);
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#endif /* CONFIG_NTP_PPS */
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/**
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* do_gettimeofday - Returns the time of day in a timeval
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* @tv: pointer to the timeval to be set
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*
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* NOTE: Users should be converted to using getnstimeofday()
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*/
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void do_gettimeofday(struct timeval *tv)
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{
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struct timespec now;
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getnstimeofday(&now);
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tv->tv_sec = now.tv_sec;
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tv->tv_usec = now.tv_nsec/1000;
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}
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EXPORT_SYMBOL(do_gettimeofday);
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/**
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* do_settimeofday - Sets the time of day
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* @tv: pointer to the timespec variable containing the new time
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*
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* Sets the time of day to the new time and update NTP and notify hrtimers
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*/
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int do_settimeofday(const struct timespec *tv)
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{
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struct timespec ts_delta;
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unsigned long flags;
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if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
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return -EINVAL;
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write_seqlock_irqsave(&timekeeper.lock, flags);
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timekeeping_forward_now();
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ts_delta.tv_sec = tv->tv_sec - timekeeper.xtime.tv_sec;
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ts_delta.tv_nsec = tv->tv_nsec - timekeeper.xtime.tv_nsec;
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timekeeper.wall_to_monotonic =
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timespec_sub(timekeeper.wall_to_monotonic, ts_delta);
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timekeeper.xtime = *tv;
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timekeeping_update(true);
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write_sequnlock_irqrestore(&timekeeper.lock, flags);
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/* signal hrtimers about time change */
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clock_was_set();
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return 0;
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}
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EXPORT_SYMBOL(do_settimeofday);
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/**
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* timekeeping_inject_offset - Adds or subtracts from the current time.
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* @tv: pointer to the timespec variable containing the offset
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*
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* Adds or subtracts an offset value from the current time.
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*/
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int timekeeping_inject_offset(struct timespec *ts)
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{
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unsigned long flags;
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if ((unsigned long)ts->tv_nsec >= NSEC_PER_SEC)
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return -EINVAL;
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write_seqlock_irqsave(&timekeeper.lock, flags);
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timekeeping_forward_now();
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timekeeper.xtime = timespec_add(timekeeper.xtime, *ts);
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timekeeper.wall_to_monotonic =
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timespec_sub(timekeeper.wall_to_monotonic, *ts);
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timekeeping_update(true);
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write_sequnlock_irqrestore(&timekeeper.lock, flags);
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/* signal hrtimers about time change */
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clock_was_set();
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return 0;
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}
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EXPORT_SYMBOL(timekeeping_inject_offset);
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/**
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* change_clocksource - Swaps clocksources if a new one is available
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*
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* Accumulates current time interval and initializes new clocksource
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*/
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static int change_clocksource(void *data)
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{
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struct clocksource *new, *old;
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unsigned long flags;
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new = (struct clocksource *) data;
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write_seqlock_irqsave(&timekeeper.lock, flags);
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timekeeping_forward_now();
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if (!new->enable || new->enable(new) == 0) {
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old = timekeeper.clock;
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timekeeper_setup_internals(new);
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if (old->disable)
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old->disable(old);
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}
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timekeeping_update(true);
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write_sequnlock_irqrestore(&timekeeper.lock, flags);
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return 0;
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}
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/**
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* timekeeping_notify - Install a new clock source
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* @clock: pointer to the clock source
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*
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* This function is called from clocksource.c after a new, better clock
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* source has been registered. The caller holds the clocksource_mutex.
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*/
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void timekeeping_notify(struct clocksource *clock)
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{
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if (timekeeper.clock == clock)
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return;
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stop_machine(change_clocksource, clock, NULL);
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tick_clock_notify();
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}
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/**
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* ktime_get_real - get the real (wall-) time in ktime_t format
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*
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* returns the time in ktime_t format
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*/
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ktime_t ktime_get_real(void)
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{
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struct timespec now;
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getnstimeofday(&now);
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return timespec_to_ktime(now);
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}
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EXPORT_SYMBOL_GPL(ktime_get_real);
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/**
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* getrawmonotonic - Returns the raw monotonic time in a timespec
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* @ts: pointer to the timespec to be set
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*
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* Returns the raw monotonic time (completely un-modified by ntp)
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*/
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void getrawmonotonic(struct timespec *ts)
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{
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unsigned long seq;
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s64 nsecs;
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do {
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seq = read_seqbegin(&timekeeper.lock);
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nsecs = timekeeping_get_ns_raw();
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*ts = timekeeper.raw_time;
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} while (read_seqretry(&timekeeper.lock, seq));
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timespec_add_ns(ts, nsecs);
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}
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EXPORT_SYMBOL(getrawmonotonic);
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/**
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* timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
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*/
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int timekeeping_valid_for_hres(void)
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{
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unsigned long seq;
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int ret;
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do {
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seq = read_seqbegin(&timekeeper.lock);
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ret = timekeeper.clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;
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} while (read_seqretry(&timekeeper.lock, seq));
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return ret;
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}
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/**
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* timekeeping_max_deferment - Returns max time the clocksource can be deferred
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*/
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u64 timekeeping_max_deferment(void)
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{
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unsigned long seq;
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u64 ret;
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do {
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seq = read_seqbegin(&timekeeper.lock);
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ret = timekeeper.clock->max_idle_ns;
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} while (read_seqretry(&timekeeper.lock, seq));
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return ret;
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}
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/**
|
|
* read_persistent_clock - Return time from the persistent clock.
|
|
*
|
|
* Weak dummy function for arches that do not yet support it.
|
|
* Reads the time from the battery backed persistent clock.
|
|
* Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
|
|
*
|
|
* XXX - Do be sure to remove it once all arches implement it.
|
|
*/
|
|
void __attribute__((weak)) read_persistent_clock(struct timespec *ts)
|
|
{
|
|
ts->tv_sec = 0;
|
|
ts->tv_nsec = 0;
|
|
}
|
|
|
|
/**
|
|
* read_boot_clock - Return time of the system start.
|
|
*
|
|
* Weak dummy function for arches that do not yet support it.
|
|
* Function to read the exact time the system has been started.
|
|
* Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
|
|
*
|
|
* XXX - Do be sure to remove it once all arches implement it.
|
|
*/
|
|
void __attribute__((weak)) read_boot_clock(struct timespec *ts)
|
|
{
|
|
ts->tv_sec = 0;
|
|
ts->tv_nsec = 0;
|
|
}
|
|
|
|
/*
|
|
* timekeeping_init - Initializes the clocksource and common timekeeping values
|
|
*/
|
|
void __init timekeeping_init(void)
|
|
{
|
|
struct clocksource *clock;
|
|
unsigned long flags;
|
|
struct timespec now, boot;
|
|
|
|
read_persistent_clock(&now);
|
|
read_boot_clock(&boot);
|
|
|
|
seqlock_init(&timekeeper.lock);
|
|
|
|
ntp_init();
|
|
|
|
write_seqlock_irqsave(&timekeeper.lock, flags);
|
|
clock = clocksource_default_clock();
|
|
if (clock->enable)
|
|
clock->enable(clock);
|
|
timekeeper_setup_internals(clock);
|
|
|
|
timekeeper.xtime.tv_sec = now.tv_sec;
|
|
timekeeper.xtime.tv_nsec = now.tv_nsec;
|
|
timekeeper.raw_time.tv_sec = 0;
|
|
timekeeper.raw_time.tv_nsec = 0;
|
|
if (boot.tv_sec == 0 && boot.tv_nsec == 0) {
|
|
boot.tv_sec = timekeeper.xtime.tv_sec;
|
|
boot.tv_nsec = timekeeper.xtime.tv_nsec;
|
|
}
|
|
set_normalized_timespec(&timekeeper.wall_to_monotonic,
|
|
-boot.tv_sec, -boot.tv_nsec);
|
|
timekeeper.total_sleep_time.tv_sec = 0;
|
|
timekeeper.total_sleep_time.tv_nsec = 0;
|
|
write_sequnlock_irqrestore(&timekeeper.lock, flags);
|
|
}
|
|
|
|
/* time in seconds when suspend began */
|
|
static struct timespec timekeeping_suspend_time;
|
|
|
|
/**
|
|
* __timekeeping_inject_sleeptime - Internal function to add sleep interval
|
|
* @delta: pointer to a timespec delta value
|
|
*
|
|
* Takes a timespec offset measuring a suspend interval and properly
|
|
* adds the sleep offset to the timekeeping variables.
|
|
*/
|
|
static void __timekeeping_inject_sleeptime(struct timespec *delta)
|
|
{
|
|
if (!timespec_valid(delta)) {
|
|
printk(KERN_WARNING "__timekeeping_inject_sleeptime: Invalid "
|
|
"sleep delta value!\n");
|
|
return;
|
|
}
|
|
|
|
timekeeper.xtime = timespec_add(timekeeper.xtime, *delta);
|
|
timekeeper.wall_to_monotonic =
|
|
timespec_sub(timekeeper.wall_to_monotonic, *delta);
|
|
timekeeper.total_sleep_time = timespec_add(
|
|
timekeeper.total_sleep_time, *delta);
|
|
}
|
|
|
|
|
|
/**
|
|
* timekeeping_inject_sleeptime - Adds suspend interval to timeekeeping values
|
|
* @delta: pointer to a timespec delta value
|
|
*
|
|
* This hook is for architectures that cannot support read_persistent_clock
|
|
* because their RTC/persistent clock is only accessible when irqs are enabled.
|
|
*
|
|
* This function should only be called by rtc_resume(), and allows
|
|
* a suspend offset to be injected into the timekeeping values.
|
|
*/
|
|
void timekeeping_inject_sleeptime(struct timespec *delta)
|
|
{
|
|
unsigned long flags;
|
|
struct timespec ts;
|
|
|
|
/* Make sure we don't set the clock twice */
|
|
read_persistent_clock(&ts);
|
|
if (!(ts.tv_sec == 0 && ts.tv_nsec == 0))
|
|
return;
|
|
|
|
write_seqlock_irqsave(&timekeeper.lock, flags);
|
|
|
|
timekeeping_forward_now();
|
|
|
|
__timekeeping_inject_sleeptime(delta);
|
|
|
|
timekeeping_update(true);
|
|
|
|
write_sequnlock_irqrestore(&timekeeper.lock, flags);
|
|
|
|
/* signal hrtimers about time change */
|
|
clock_was_set();
|
|
}
|
|
|
|
|
|
/**
|
|
* timekeeping_resume - Resumes the generic timekeeping subsystem.
|
|
*
|
|
* This is for the generic clocksource timekeeping.
|
|
* xtime/wall_to_monotonic/jiffies/etc are
|
|
* still managed by arch specific suspend/resume code.
|
|
*/
|
|
static void timekeeping_resume(void)
|
|
{
|
|
unsigned long flags;
|
|
struct timespec ts;
|
|
|
|
read_persistent_clock(&ts);
|
|
|
|
clocksource_resume();
|
|
|
|
write_seqlock_irqsave(&timekeeper.lock, flags);
|
|
|
|
if (timespec_compare(&ts, &timekeeping_suspend_time) > 0) {
|
|
ts = timespec_sub(ts, timekeeping_suspend_time);
|
|
__timekeeping_inject_sleeptime(&ts);
|
|
}
|
|
/* re-base the last cycle value */
|
|
timekeeper.clock->cycle_last = timekeeper.clock->read(timekeeper.clock);
|
|
timekeeper.ntp_error = 0;
|
|
timekeeping_suspended = 0;
|
|
write_sequnlock_irqrestore(&timekeeper.lock, flags);
|
|
|
|
touch_softlockup_watchdog();
|
|
|
|
clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL);
|
|
|
|
/* Resume hrtimers */
|
|
hrtimers_resume();
|
|
}
|
|
|
|
static int timekeeping_suspend(void)
|
|
{
|
|
unsigned long flags;
|
|
struct timespec delta, delta_delta;
|
|
static struct timespec old_delta;
|
|
|
|
read_persistent_clock(&timekeeping_suspend_time);
|
|
|
|
write_seqlock_irqsave(&timekeeper.lock, flags);
|
|
timekeeping_forward_now();
|
|
timekeeping_suspended = 1;
|
|
|
|
/*
|
|
* To avoid drift caused by repeated suspend/resumes,
|
|
* which each can add ~1 second drift error,
|
|
* try to compensate so the difference in system time
|
|
* and persistent_clock time stays close to constant.
|
|
*/
|
|
delta = timespec_sub(timekeeper.xtime, timekeeping_suspend_time);
|
|
delta_delta = timespec_sub(delta, old_delta);
|
|
if (abs(delta_delta.tv_sec) >= 2) {
|
|
/*
|
|
* if delta_delta is too large, assume time correction
|
|
* has occured and set old_delta to the current delta.
|
|
*/
|
|
old_delta = delta;
|
|
} else {
|
|
/* Otherwise try to adjust old_system to compensate */
|
|
timekeeping_suspend_time =
|
|
timespec_add(timekeeping_suspend_time, delta_delta);
|
|
}
|
|
write_sequnlock_irqrestore(&timekeeper.lock, flags);
|
|
|
|
clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL);
|
|
clocksource_suspend();
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* sysfs resume/suspend bits for timekeeping */
|
|
static struct syscore_ops timekeeping_syscore_ops = {
|
|
.resume = timekeeping_resume,
|
|
.suspend = timekeeping_suspend,
|
|
};
|
|
|
|
static int __init timekeeping_init_ops(void)
|
|
{
|
|
register_syscore_ops(&timekeeping_syscore_ops);
|
|
return 0;
|
|
}
|
|
|
|
device_initcall(timekeeping_init_ops);
|
|
|
|
/*
|
|
* If the error is already larger, we look ahead even further
|
|
* to compensate for late or lost adjustments.
|
|
*/
|
|
static __always_inline int timekeeping_bigadjust(s64 error, s64 *interval,
|
|
s64 *offset)
|
|
{
|
|
s64 tick_error, i;
|
|
u32 look_ahead, adj;
|
|
s32 error2, mult;
|
|
|
|
/*
|
|
* Use the current error value to determine how much to look ahead.
|
|
* The larger the error the slower we adjust for it to avoid problems
|
|
* with losing too many ticks, otherwise we would overadjust and
|
|
* produce an even larger error. The smaller the adjustment the
|
|
* faster we try to adjust for it, as lost ticks can do less harm
|
|
* here. This is tuned so that an error of about 1 msec is adjusted
|
|
* within about 1 sec (or 2^20 nsec in 2^SHIFT_HZ ticks).
|
|
*/
|
|
error2 = timekeeper.ntp_error >> (NTP_SCALE_SHIFT + 22 - 2 * SHIFT_HZ);
|
|
error2 = abs(error2);
|
|
for (look_ahead = 0; error2 > 0; look_ahead++)
|
|
error2 >>= 2;
|
|
|
|
/*
|
|
* Now calculate the error in (1 << look_ahead) ticks, but first
|
|
* remove the single look ahead already included in the error.
|
|
*/
|
|
tick_error = ntp_tick_length() >> (timekeeper.ntp_error_shift + 1);
|
|
tick_error -= timekeeper.xtime_interval >> 1;
|
|
error = ((error - tick_error) >> look_ahead) + tick_error;
|
|
|
|
/* Finally calculate the adjustment shift value. */
|
|
i = *interval;
|
|
mult = 1;
|
|
if (error < 0) {
|
|
error = -error;
|
|
*interval = -*interval;
|
|
*offset = -*offset;
|
|
mult = -1;
|
|
}
|
|
for (adj = 0; error > i; adj++)
|
|
error >>= 1;
|
|
|
|
*interval <<= adj;
|
|
*offset <<= adj;
|
|
return mult << adj;
|
|
}
|
|
|
|
/*
|
|
* Adjust the multiplier to reduce the error value,
|
|
* this is optimized for the most common adjustments of -1,0,1,
|
|
* for other values we can do a bit more work.
|
|
*/
|
|
static void timekeeping_adjust(s64 offset)
|
|
{
|
|
s64 error, interval = timekeeper.cycle_interval;
|
|
int adj;
|
|
|
|
/*
|
|
* The point of this is to check if the error is greater than half
|
|
* an interval.
|
|
*
|
|
* First we shift it down from NTP_SHIFT to clocksource->shifted nsecs.
|
|
*
|
|
* Note we subtract one in the shift, so that error is really error*2.
|
|
* This "saves" dividing(shifting) interval twice, but keeps the
|
|
* (error > interval) comparison as still measuring if error is
|
|
* larger than half an interval.
|
|
*
|
|
* Note: It does not "save" on aggravation when reading the code.
|
|
*/
|
|
error = timekeeper.ntp_error >> (timekeeper.ntp_error_shift - 1);
|
|
if (error > interval) {
|
|
/*
|
|
* We now divide error by 4(via shift), which checks if
|
|
* the error is greater than twice the interval.
|
|
* If it is greater, we need a bigadjust, if its smaller,
|
|
* we can adjust by 1.
|
|
*/
|
|
error >>= 2;
|
|
/*
|
|
* XXX - In update_wall_time, we round up to the next
|
|
* nanosecond, and store the amount rounded up into
|
|
* the error. This causes the likely below to be unlikely.
|
|
*
|
|
* The proper fix is to avoid rounding up by using
|
|
* the high precision timekeeper.xtime_nsec instead of
|
|
* xtime.tv_nsec everywhere. Fixing this will take some
|
|
* time.
|
|
*/
|
|
if (likely(error <= interval))
|
|
adj = 1;
|
|
else
|
|
adj = timekeeping_bigadjust(error, &interval, &offset);
|
|
} else if (error < -interval) {
|
|
/* See comment above, this is just switched for the negative */
|
|
error >>= 2;
|
|
if (likely(error >= -interval)) {
|
|
adj = -1;
|
|
interval = -interval;
|
|
offset = -offset;
|
|
} else
|
|
adj = timekeeping_bigadjust(error, &interval, &offset);
|
|
} else /* No adjustment needed */
|
|
return;
|
|
|
|
if (unlikely(timekeeper.clock->maxadj &&
|
|
(timekeeper.mult + adj >
|
|
timekeeper.clock->mult + timekeeper.clock->maxadj))) {
|
|
printk_once(KERN_WARNING
|
|
"Adjusting %s more than 11%% (%ld vs %ld)\n",
|
|
timekeeper.clock->name, (long)timekeeper.mult + adj,
|
|
(long)timekeeper.clock->mult +
|
|
timekeeper.clock->maxadj);
|
|
}
|
|
/*
|
|
* So the following can be confusing.
|
|
*
|
|
* To keep things simple, lets assume adj == 1 for now.
|
|
*
|
|
* When adj != 1, remember that the interval and offset values
|
|
* have been appropriately scaled so the math is the same.
|
|
*
|
|
* The basic idea here is that we're increasing the multiplier
|
|
* by one, this causes the xtime_interval to be incremented by
|
|
* one cycle_interval. This is because:
|
|
* xtime_interval = cycle_interval * mult
|
|
* So if mult is being incremented by one:
|
|
* xtime_interval = cycle_interval * (mult + 1)
|
|
* Its the same as:
|
|
* xtime_interval = (cycle_interval * mult) + cycle_interval
|
|
* Which can be shortened to:
|
|
* xtime_interval += cycle_interval
|
|
*
|
|
* So offset stores the non-accumulated cycles. Thus the current
|
|
* time (in shifted nanoseconds) is:
|
|
* now = (offset * adj) + xtime_nsec
|
|
* Now, even though we're adjusting the clock frequency, we have
|
|
* to keep time consistent. In other words, we can't jump back
|
|
* in time, and we also want to avoid jumping forward in time.
|
|
*
|
|
* So given the same offset value, we need the time to be the same
|
|
* both before and after the freq adjustment.
|
|
* now = (offset * adj_1) + xtime_nsec_1
|
|
* now = (offset * adj_2) + xtime_nsec_2
|
|
* So:
|
|
* (offset * adj_1) + xtime_nsec_1 =
|
|
* (offset * adj_2) + xtime_nsec_2
|
|
* And we know:
|
|
* adj_2 = adj_1 + 1
|
|
* So:
|
|
* (offset * adj_1) + xtime_nsec_1 =
|
|
* (offset * (adj_1+1)) + xtime_nsec_2
|
|
* (offset * adj_1) + xtime_nsec_1 =
|
|
* (offset * adj_1) + offset + xtime_nsec_2
|
|
* Canceling the sides:
|
|
* xtime_nsec_1 = offset + xtime_nsec_2
|
|
* Which gives us:
|
|
* xtime_nsec_2 = xtime_nsec_1 - offset
|
|
* Which simplfies to:
|
|
* xtime_nsec -= offset
|
|
*
|
|
* XXX - TODO: Doc ntp_error calculation.
|
|
*/
|
|
timekeeper.mult += adj;
|
|
timekeeper.xtime_interval += interval;
|
|
timekeeper.xtime_nsec -= offset;
|
|
timekeeper.ntp_error -= (interval - offset) <<
|
|
timekeeper.ntp_error_shift;
|
|
}
|
|
|
|
|
|
/**
|
|
* logarithmic_accumulation - shifted accumulation of cycles
|
|
*
|
|
* This functions accumulates a shifted interval of cycles into
|
|
* into a shifted interval nanoseconds. Allows for O(log) accumulation
|
|
* loop.
|
|
*
|
|
* Returns the unconsumed cycles.
|
|
*/
|
|
static cycle_t logarithmic_accumulation(cycle_t offset, int shift)
|
|
{
|
|
u64 nsecps = (u64)NSEC_PER_SEC << timekeeper.shift;
|
|
u64 raw_nsecs;
|
|
|
|
/* If the offset is smaller than a shifted interval, do nothing */
|
|
if (offset < timekeeper.cycle_interval<<shift)
|
|
return offset;
|
|
|
|
/* Accumulate one shifted interval */
|
|
offset -= timekeeper.cycle_interval << shift;
|
|
timekeeper.clock->cycle_last += timekeeper.cycle_interval << shift;
|
|
|
|
timekeeper.xtime_nsec += timekeeper.xtime_interval << shift;
|
|
while (timekeeper.xtime_nsec >= nsecps) {
|
|
int leap;
|
|
timekeeper.xtime_nsec -= nsecps;
|
|
timekeeper.xtime.tv_sec++;
|
|
leap = second_overflow(timekeeper.xtime.tv_sec);
|
|
timekeeper.xtime.tv_sec += leap;
|
|
}
|
|
|
|
/* Accumulate raw time */
|
|
raw_nsecs = timekeeper.raw_interval << shift;
|
|
raw_nsecs += timekeeper.raw_time.tv_nsec;
|
|
if (raw_nsecs >= NSEC_PER_SEC) {
|
|
u64 raw_secs = raw_nsecs;
|
|
raw_nsecs = do_div(raw_secs, NSEC_PER_SEC);
|
|
timekeeper.raw_time.tv_sec += raw_secs;
|
|
}
|
|
timekeeper.raw_time.tv_nsec = raw_nsecs;
|
|
|
|
/* Accumulate error between NTP and clock interval */
|
|
timekeeper.ntp_error += ntp_tick_length() << shift;
|
|
timekeeper.ntp_error -=
|
|
(timekeeper.xtime_interval + timekeeper.xtime_remainder) <<
|
|
(timekeeper.ntp_error_shift + shift);
|
|
|
|
return offset;
|
|
}
|
|
|
|
|
|
/**
|
|
* update_wall_time - Uses the current clocksource to increment the wall time
|
|
*
|
|
*/
|
|
static void update_wall_time(void)
|
|
{
|
|
struct clocksource *clock;
|
|
cycle_t offset;
|
|
int shift = 0, maxshift;
|
|
unsigned long flags;
|
|
|
|
write_seqlock_irqsave(&timekeeper.lock, flags);
|
|
|
|
/* Make sure we're fully resumed: */
|
|
if (unlikely(timekeeping_suspended))
|
|
goto out;
|
|
|
|
clock = timekeeper.clock;
|
|
|
|
#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
|
|
offset = timekeeper.cycle_interval;
|
|
#else
|
|
offset = (clock->read(clock) - clock->cycle_last) & clock->mask;
|
|
#endif
|
|
timekeeper.xtime_nsec = (s64)timekeeper.xtime.tv_nsec <<
|
|
timekeeper.shift;
|
|
|
|
/*
|
|
* With NO_HZ we may have to accumulate many cycle_intervals
|
|
* (think "ticks") worth of time at once. To do this efficiently,
|
|
* we calculate the largest doubling multiple of cycle_intervals
|
|
* that is smaller than the offset. We then accumulate that
|
|
* chunk in one go, and then try to consume the next smaller
|
|
* doubled multiple.
|
|
*/
|
|
shift = ilog2(offset) - ilog2(timekeeper.cycle_interval);
|
|
shift = max(0, shift);
|
|
/* Bound shift to one less than what overflows tick_length */
|
|
maxshift = (64 - (ilog2(ntp_tick_length())+1)) - 1;
|
|
shift = min(shift, maxshift);
|
|
while (offset >= timekeeper.cycle_interval) {
|
|
offset = logarithmic_accumulation(offset, shift);
|
|
if(offset < timekeeper.cycle_interval<<shift)
|
|
shift--;
|
|
}
|
|
|
|
/* correct the clock when NTP error is too big */
|
|
timekeeping_adjust(offset);
|
|
|
|
/*
|
|
* Since in the loop above, we accumulate any amount of time
|
|
* in xtime_nsec over a second into xtime.tv_sec, its possible for
|
|
* xtime_nsec to be fairly small after the loop. Further, if we're
|
|
* slightly speeding the clocksource up in timekeeping_adjust(),
|
|
* its possible the required corrective factor to xtime_nsec could
|
|
* cause it to underflow.
|
|
*
|
|
* Now, we cannot simply roll the accumulated second back, since
|
|
* the NTP subsystem has been notified via second_overflow. So
|
|
* instead we push xtime_nsec forward by the amount we underflowed,
|
|
* and add that amount into the error.
|
|
*
|
|
* We'll correct this error next time through this function, when
|
|
* xtime_nsec is not as small.
|
|
*/
|
|
if (unlikely((s64)timekeeper.xtime_nsec < 0)) {
|
|
s64 neg = -(s64)timekeeper.xtime_nsec;
|
|
timekeeper.xtime_nsec = 0;
|
|
timekeeper.ntp_error += neg << timekeeper.ntp_error_shift;
|
|
}
|
|
|
|
|
|
/*
|
|
* Store full nanoseconds into xtime after rounding it up and
|
|
* add the remainder to the error difference.
|
|
*/
|
|
timekeeper.xtime.tv_nsec = ((s64)timekeeper.xtime_nsec >>
|
|
timekeeper.shift) + 1;
|
|
timekeeper.xtime_nsec -= (s64)timekeeper.xtime.tv_nsec <<
|
|
timekeeper.shift;
|
|
timekeeper.ntp_error += timekeeper.xtime_nsec <<
|
|
timekeeper.ntp_error_shift;
|
|
|
|
/*
|
|
* Finally, make sure that after the rounding
|
|
* xtime.tv_nsec isn't larger than NSEC_PER_SEC
|
|
*/
|
|
if (unlikely(timekeeper.xtime.tv_nsec >= NSEC_PER_SEC)) {
|
|
int leap;
|
|
timekeeper.xtime.tv_nsec -= NSEC_PER_SEC;
|
|
timekeeper.xtime.tv_sec++;
|
|
leap = second_overflow(timekeeper.xtime.tv_sec);
|
|
timekeeper.xtime.tv_sec += leap;
|
|
}
|
|
|
|
timekeeping_update(false);
|
|
|
|
out:
|
|
write_sequnlock_irqrestore(&timekeeper.lock, flags);
|
|
|
|
}
|
|
|
|
/**
|
|
* getboottime - Return the real time of system boot.
|
|
* @ts: pointer to the timespec to be set
|
|
*
|
|
* Returns the wall-time of boot in a timespec.
|
|
*
|
|
* This is based on the wall_to_monotonic offset and the total suspend
|
|
* time. Calls to settimeofday will affect the value returned (which
|
|
* basically means that however wrong your real time clock is at boot time,
|
|
* you get the right time here).
|
|
*/
|
|
void getboottime(struct timespec *ts)
|
|
{
|
|
struct timespec boottime = {
|
|
.tv_sec = timekeeper.wall_to_monotonic.tv_sec +
|
|
timekeeper.total_sleep_time.tv_sec,
|
|
.tv_nsec = timekeeper.wall_to_monotonic.tv_nsec +
|
|
timekeeper.total_sleep_time.tv_nsec
|
|
};
|
|
|
|
set_normalized_timespec(ts, -boottime.tv_sec, -boottime.tv_nsec);
|
|
}
|
|
EXPORT_SYMBOL_GPL(getboottime);
|
|
|
|
|
|
/**
|
|
* get_monotonic_boottime - Returns monotonic time since boot
|
|
* @ts: pointer to the timespec to be set
|
|
*
|
|
* Returns the monotonic time since boot in a timespec.
|
|
*
|
|
* This is similar to CLOCK_MONTONIC/ktime_get_ts, but also
|
|
* includes the time spent in suspend.
|
|
*/
|
|
void get_monotonic_boottime(struct timespec *ts)
|
|
{
|
|
struct timespec tomono, sleep;
|
|
unsigned int seq;
|
|
s64 nsecs;
|
|
|
|
WARN_ON(timekeeping_suspended);
|
|
|
|
do {
|
|
seq = read_seqbegin(&timekeeper.lock);
|
|
*ts = timekeeper.xtime;
|
|
tomono = timekeeper.wall_to_monotonic;
|
|
sleep = timekeeper.total_sleep_time;
|
|
nsecs = timekeeping_get_ns();
|
|
|
|
} while (read_seqretry(&timekeeper.lock, seq));
|
|
|
|
set_normalized_timespec(ts, ts->tv_sec + tomono.tv_sec + sleep.tv_sec,
|
|
ts->tv_nsec + tomono.tv_nsec + sleep.tv_nsec + nsecs);
|
|
}
|
|
EXPORT_SYMBOL_GPL(get_monotonic_boottime);
|
|
|
|
/**
|
|
* ktime_get_boottime - Returns monotonic time since boot in a ktime
|
|
*
|
|
* Returns the monotonic time since boot in a ktime
|
|
*
|
|
* This is similar to CLOCK_MONTONIC/ktime_get, but also
|
|
* includes the time spent in suspend.
|
|
*/
|
|
ktime_t ktime_get_boottime(void)
|
|
{
|
|
struct timespec ts;
|
|
|
|
get_monotonic_boottime(&ts);
|
|
return timespec_to_ktime(ts);
|
|
}
|
|
EXPORT_SYMBOL_GPL(ktime_get_boottime);
|
|
|
|
/**
|
|
* monotonic_to_bootbased - Convert the monotonic time to boot based.
|
|
* @ts: pointer to the timespec to be converted
|
|
*/
|
|
void monotonic_to_bootbased(struct timespec *ts)
|
|
{
|
|
*ts = timespec_add(*ts, timekeeper.total_sleep_time);
|
|
}
|
|
EXPORT_SYMBOL_GPL(monotonic_to_bootbased);
|
|
|
|
unsigned long get_seconds(void)
|
|
{
|
|
return timekeeper.xtime.tv_sec;
|
|
}
|
|
EXPORT_SYMBOL(get_seconds);
|
|
|
|
struct timespec __current_kernel_time(void)
|
|
{
|
|
return timekeeper.xtime;
|
|
}
|
|
|
|
struct timespec current_kernel_time(void)
|
|
{
|
|
struct timespec now;
|
|
unsigned long seq;
|
|
|
|
do {
|
|
seq = read_seqbegin(&timekeeper.lock);
|
|
|
|
now = timekeeper.xtime;
|
|
} while (read_seqretry(&timekeeper.lock, seq));
|
|
|
|
return now;
|
|
}
|
|
EXPORT_SYMBOL(current_kernel_time);
|
|
|
|
struct timespec get_monotonic_coarse(void)
|
|
{
|
|
struct timespec now, mono;
|
|
unsigned long seq;
|
|
|
|
do {
|
|
seq = read_seqbegin(&timekeeper.lock);
|
|
|
|
now = timekeeper.xtime;
|
|
mono = timekeeper.wall_to_monotonic;
|
|
} while (read_seqretry(&timekeeper.lock, seq));
|
|
|
|
set_normalized_timespec(&now, now.tv_sec + mono.tv_sec,
|
|
now.tv_nsec + mono.tv_nsec);
|
|
return now;
|
|
}
|
|
|
|
/*
|
|
* The 64-bit jiffies value is not atomic - you MUST NOT read it
|
|
* without sampling the sequence number in xtime_lock.
|
|
* jiffies is defined in the linker script...
|
|
*/
|
|
void do_timer(unsigned long ticks)
|
|
{
|
|
jiffies_64 += ticks;
|
|
update_wall_time();
|
|
calc_global_load(ticks);
|
|
}
|
|
|
|
/**
|
|
* get_xtime_and_monotonic_and_sleep_offset() - get xtime, wall_to_monotonic,
|
|
* and sleep offsets.
|
|
* @xtim: pointer to timespec to be set with xtime
|
|
* @wtom: pointer to timespec to be set with wall_to_monotonic
|
|
* @sleep: pointer to timespec to be set with time in suspend
|
|
*/
|
|
void get_xtime_and_monotonic_and_sleep_offset(struct timespec *xtim,
|
|
struct timespec *wtom, struct timespec *sleep)
|
|
{
|
|
unsigned long seq;
|
|
|
|
do {
|
|
seq = read_seqbegin(&timekeeper.lock);
|
|
*xtim = timekeeper.xtime;
|
|
*wtom = timekeeper.wall_to_monotonic;
|
|
*sleep = timekeeper.total_sleep_time;
|
|
} while (read_seqretry(&timekeeper.lock, seq));
|
|
}
|
|
|
|
/**
|
|
* ktime_get_monotonic_offset() - get wall_to_monotonic in ktime_t format
|
|
*/
|
|
ktime_t ktime_get_monotonic_offset(void)
|
|
{
|
|
unsigned long seq;
|
|
struct timespec wtom;
|
|
|
|
do {
|
|
seq = read_seqbegin(&timekeeper.lock);
|
|
wtom = timekeeper.wall_to_monotonic;
|
|
} while (read_seqretry(&timekeeper.lock, seq));
|
|
|
|
return timespec_to_ktime(wtom);
|
|
}
|
|
EXPORT_SYMBOL_GPL(ktime_get_monotonic_offset);
|
|
|
|
|
|
/**
|
|
* xtime_update() - advances the timekeeping infrastructure
|
|
* @ticks: number of ticks, that have elapsed since the last call.
|
|
*
|
|
* Must be called with interrupts disabled.
|
|
*/
|
|
void xtime_update(unsigned long ticks)
|
|
{
|
|
write_seqlock(&xtime_lock);
|
|
do_timer(ticks);
|
|
write_sequnlock(&xtime_lock);
|
|
}
|