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authorAnton Arapov <anton@redhat.com>2012-04-16 10:05:28 +0200
committerAnton Arapov <anton@redhat.com>2012-04-16 10:05:28 +0200
commitb4b6116a13633898cf868f2f103c96a90c4c20f8 (patch)
tree93d1b7e2cfcdf473d8d4ff3ad141fa864f8491f6 /kernel/time/timekeeping.c
parentedd4be777c953e5faafc80d091d3084b4343f5d3 (diff)
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fedora kernel: d9aad82f3319f3cfd1aebc01234254ef0c37ad84v3.3.2-1
Signed-off-by: Anton Arapov <anton@redhat.com>
Diffstat (limited to 'kernel/time/timekeeping.c')
-rw-r--r--kernel/time/timekeeping.c1238
1 files changed, 1238 insertions, 0 deletions
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
new file mode 100644
index 00000000000..9cffcab0565
--- /dev/null
+++ b/kernel/time/timekeeping.c
@@ -0,0 +1,1238 @@
+/*
+ * linux/kernel/time/timekeeping.c
+ *
+ * Kernel timekeeping code and accessor functions
+ *
+ * This code was moved from linux/kernel/timer.c.
+ * Please see that file for copyright and history logs.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/interrupt.h>
+#include <linux/percpu.h>
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/sched.h>
+#include <linux/syscore_ops.h>
+#include <linux/clocksource.h>
+#include <linux/jiffies.h>
+#include <linux/time.h>
+#include <linux/tick.h>
+#include <linux/stop_machine.h>
+
+/* Structure holding internal timekeeping values. */
+struct timekeeper {
+ /* Current clocksource used for timekeeping. */
+ struct clocksource *clock;
+ /* The shift value of the current clocksource. */
+ int shift;
+
+ /* Number of clock cycles in one NTP interval. */
+ cycle_t cycle_interval;
+ /* Number of clock shifted nano seconds in one NTP interval. */
+ u64 xtime_interval;
+ /* shifted nano seconds left over when rounding cycle_interval */
+ s64 xtime_remainder;
+ /* Raw nano seconds accumulated per NTP interval. */
+ u32 raw_interval;
+
+ /* Clock shifted nano seconds remainder not stored in xtime.tv_nsec. */
+ u64 xtime_nsec;
+ /* Difference between accumulated time and NTP time in ntp
+ * shifted nano seconds. */
+ s64 ntp_error;
+ /* Shift conversion between clock shifted nano seconds and
+ * ntp shifted nano seconds. */
+ int ntp_error_shift;
+ /* NTP adjusted clock multiplier */
+ u32 mult;
+};
+
+static struct timekeeper timekeeper;
+
+/**
+ * timekeeper_setup_internals - Set up internals to use clocksource clock.
+ *
+ * @clock: Pointer to clocksource.
+ *
+ * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment
+ * pair and interval request.
+ *
+ * Unless you're the timekeeping code, you should not be using this!
+ */
+static void timekeeper_setup_internals(struct clocksource *clock)
+{
+ cycle_t interval;
+ u64 tmp, ntpinterval;
+
+ timekeeper.clock = clock;
+ clock->cycle_last = clock->read(clock);
+
+ /* Do the ns -> cycle conversion first, using original mult */
+ tmp = NTP_INTERVAL_LENGTH;
+ tmp <<= clock->shift;
+ ntpinterval = tmp;
+ tmp += clock->mult/2;
+ do_div(tmp, clock->mult);
+ if (tmp == 0)
+ tmp = 1;
+
+ interval = (cycle_t) tmp;
+ timekeeper.cycle_interval = interval;
+
+ /* Go back from cycles -> shifted ns */
+ timekeeper.xtime_interval = (u64) interval * clock->mult;
+ timekeeper.xtime_remainder = ntpinterval - timekeeper.xtime_interval;
+ timekeeper.raw_interval =
+ ((u64) interval * clock->mult) >> clock->shift;
+
+ timekeeper.xtime_nsec = 0;
+ timekeeper.shift = clock->shift;
+
+ timekeeper.ntp_error = 0;
+ timekeeper.ntp_error_shift = NTP_SCALE_SHIFT - clock->shift;
+
+ /*
+ * The timekeeper keeps its own mult values for the currently
+ * active clocksource. These value will be adjusted via NTP
+ * to counteract clock drifting.
+ */
+ timekeeper.mult = clock->mult;
+}
+
+/* Timekeeper helper functions. */
+static inline s64 timekeeping_get_ns(void)
+{
+ cycle_t cycle_now, cycle_delta;
+ struct clocksource *clock;
+
+ /* read clocksource: */
+ clock = timekeeper.clock;
+ cycle_now = clock->read(clock);
+
+ /* calculate the delta since the last update_wall_time: */
+ cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
+
+ /* return delta convert to nanoseconds using ntp adjusted mult. */
+ return clocksource_cyc2ns(cycle_delta, timekeeper.mult,
+ timekeeper.shift);
+}
+
+static inline s64 timekeeping_get_ns_raw(void)
+{
+ cycle_t cycle_now, cycle_delta;
+ struct clocksource *clock;
+
+ /* read clocksource: */
+ clock = timekeeper.clock;
+ cycle_now = clock->read(clock);
+
+ /* calculate the delta since the last update_wall_time: */
+ cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
+
+ /* return delta convert to nanoseconds. */
+ return clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift);
+}
+
+/*
+ * This read-write spinlock protects us from races in SMP while
+ * playing with xtime.
+ */
+__cacheline_aligned_in_smp DEFINE_SEQLOCK(xtime_lock);
+
+
+/*
+ * The current time
+ * wall_to_monotonic is what we need to add to xtime (or xtime corrected
+ * for sub jiffie times) to get to monotonic time. Monotonic is pegged
+ * at zero at system boot time, so wall_to_monotonic will be negative,
+ * however, we will ALWAYS keep the tv_nsec part positive so we can use
+ * the usual normalization.
+ *
+ * wall_to_monotonic is moved after resume from suspend for the monotonic
+ * time not to jump. We need to add total_sleep_time to wall_to_monotonic
+ * to get the real boot based time offset.
+ *
+ * - wall_to_monotonic is no longer the boot time, getboottime must be
+ * used instead.
+ */
+static struct timespec xtime __attribute__ ((aligned (16)));
+static struct timespec wall_to_monotonic __attribute__ ((aligned (16)));
+static struct timespec total_sleep_time;
+
+/*
+ * The raw monotonic time for the CLOCK_MONOTONIC_RAW posix clock.
+ */
+static struct timespec raw_time;
+
+/* flag for if timekeeping is suspended */
+int __read_mostly timekeeping_suspended;
+
+/* must hold xtime_lock */
+void timekeeping_leap_insert(int leapsecond)
+{
+ xtime.tv_sec += leapsecond;
+ wall_to_monotonic.tv_sec -= leapsecond;
+ update_vsyscall(&xtime, &wall_to_monotonic, timekeeper.clock,
+ timekeeper.mult);
+}
+
+/**
+ * timekeeping_forward_now - update clock to the current time
+ *
+ * Forward the current clock to update its state since the last call to
+ * update_wall_time(). This is useful before significant clock changes,
+ * as it avoids having to deal with this time offset explicitly.
+ */
+static void timekeeping_forward_now(void)
+{
+ cycle_t cycle_now, cycle_delta;
+ struct clocksource *clock;
+ s64 nsec;
+
+ clock = timekeeper.clock;
+ cycle_now = clock->read(clock);
+ cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
+ clock->cycle_last = cycle_now;
+
+ nsec = clocksource_cyc2ns(cycle_delta, timekeeper.mult,
+ timekeeper.shift);
+
+ /* If arch requires, add in gettimeoffset() */
+ nsec += arch_gettimeoffset();
+
+ timespec_add_ns(&xtime, nsec);
+
+ nsec = clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift);
+ timespec_add_ns(&raw_time, nsec);
+}
+
+/**
+ * getnstimeofday - Returns the time of day in a timespec
+ * @ts: pointer to the timespec to be set
+ *
+ * Returns the time of day in a timespec.
+ */
+void getnstimeofday(struct timespec *ts)
+{
+ unsigned long seq;
+ s64 nsecs;
+
+ WARN_ON(timekeeping_suspended);
+
+ do {
+ seq = read_seqbegin(&xtime_lock);
+
+ *ts = xtime;
+ nsecs = timekeeping_get_ns();
+
+ /* If arch requires, add in gettimeoffset() */
+ nsecs += arch_gettimeoffset();
+
+ } while (read_seqretry(&xtime_lock, seq));
+
+ timespec_add_ns(ts, nsecs);
+}
+
+EXPORT_SYMBOL(getnstimeofday);
+
+ktime_t ktime_get(void)
+{
+ unsigned int seq;
+ s64 secs, nsecs;
+
+ WARN_ON(timekeeping_suspended);
+
+ do {
+ seq = read_seqbegin(&xtime_lock);
+ secs = xtime.tv_sec + wall_to_monotonic.tv_sec;
+ nsecs = xtime.tv_nsec + wall_to_monotonic.tv_nsec;
+ nsecs += timekeeping_get_ns();
+ /* If arch requires, add in gettimeoffset() */
+ nsecs += arch_gettimeoffset();
+
+ } while (read_seqretry(&xtime_lock, seq));
+ /*
+ * Use ktime_set/ktime_add_ns to create a proper ktime on
+ * 32-bit architectures without CONFIG_KTIME_SCALAR.
+ */
+ return ktime_add_ns(ktime_set(secs, 0), nsecs);
+}
+EXPORT_SYMBOL_GPL(ktime_get);
+
+/**
+ * ktime_get_ts - get the monotonic clock in timespec format
+ * @ts: pointer to timespec variable
+ *
+ * The function calculates the monotonic clock from the realtime
+ * clock and the wall_to_monotonic offset and stores the result
+ * in normalized timespec format in the variable pointed to by @ts.
+ */
+void ktime_get_ts(struct timespec *ts)
+{
+ struct timespec tomono;
+ unsigned int seq;
+ s64 nsecs;
+
+ WARN_ON(timekeeping_suspended);
+
+ do {
+ seq = read_seqbegin(&xtime_lock);
+ *ts = xtime;
+ tomono = wall_to_monotonic;
+ nsecs = timekeeping_get_ns();
+ /* If arch requires, add in gettimeoffset() */
+ nsecs += arch_gettimeoffset();
+
+ } while (read_seqretry(&xtime_lock, seq));
+
+ set_normalized_timespec(ts, ts->tv_sec + tomono.tv_sec,
+ ts->tv_nsec + tomono.tv_nsec + nsecs);
+}
+EXPORT_SYMBOL_GPL(ktime_get_ts);
+
+#ifdef CONFIG_NTP_PPS
+
+/**
+ * getnstime_raw_and_real - get day and raw monotonic time in timespec format
+ * @ts_raw: pointer to the timespec to be set to raw monotonic time
+ * @ts_real: pointer to the timespec to be set to the time of day
+ *
+ * This function reads both the time of day and raw monotonic time at the
+ * same time atomically and stores the resulting timestamps in timespec
+ * format.
+ */
+void getnstime_raw_and_real(struct timespec *ts_raw, struct timespec *ts_real)
+{
+ unsigned long seq;
+ s64 nsecs_raw, nsecs_real;
+
+ WARN_ON_ONCE(timekeeping_suspended);
+
+ do {
+ u32 arch_offset;
+
+ seq = read_seqbegin(&xtime_lock);
+
+ *ts_raw = raw_time;
+ *ts_real = xtime;
+
+ nsecs_raw = timekeeping_get_ns_raw();
+ nsecs_real = timekeeping_get_ns();
+
+ /* If arch requires, add in gettimeoffset() */
+ arch_offset = arch_gettimeoffset();
+ nsecs_raw += arch_offset;
+ nsecs_real += arch_offset;
+
+ } while (read_seqretry(&xtime_lock, seq));
+
+ timespec_add_ns(ts_raw, nsecs_raw);
+ timespec_add_ns(ts_real, nsecs_real);
+}
+EXPORT_SYMBOL(getnstime_raw_and_real);
+
+#endif /* CONFIG_NTP_PPS */
+
+/**
+ * do_gettimeofday - Returns the time of day in a timeval
+ * @tv: pointer to the timeval to be set
+ *
+ * NOTE: Users should be converted to using getnstimeofday()
+ */
+void do_gettimeofday(struct timeval *tv)
+{
+ struct timespec now;
+
+ getnstimeofday(&now);
+ tv->tv_sec = now.tv_sec;
+ tv->tv_usec = now.tv_nsec/1000;
+}
+
+EXPORT_SYMBOL(do_gettimeofday);
+/**
+ * do_settimeofday - Sets the time of day
+ * @tv: pointer to the timespec variable containing the new time
+ *
+ * Sets the time of day to the new time and update NTP and notify hrtimers
+ */
+int do_settimeofday(const struct timespec *tv)
+{
+ struct timespec ts_delta;
+ unsigned long flags;
+
+ if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
+ return -EINVAL;
+
+ write_seqlock_irqsave(&xtime_lock, flags);
+
+ timekeeping_forward_now();
+
+ ts_delta.tv_sec = tv->tv_sec - xtime.tv_sec;
+ ts_delta.tv_nsec = tv->tv_nsec - xtime.tv_nsec;
+ wall_to_monotonic = timespec_sub(wall_to_monotonic, ts_delta);
+
+ xtime = *tv;
+
+ timekeeper.ntp_error = 0;
+ ntp_clear();
+
+ update_vsyscall(&xtime, &wall_to_monotonic, timekeeper.clock,
+ timekeeper.mult);
+
+ write_sequnlock_irqrestore(&xtime_lock, flags);
+
+ /* signal hrtimers about time change */
+ clock_was_set();
+
+ return 0;
+}
+
+EXPORT_SYMBOL(do_settimeofday);
+
+
+/**
+ * timekeeping_inject_offset - Adds or subtracts from the current time.
+ * @tv: pointer to the timespec variable containing the offset
+ *
+ * Adds or subtracts an offset value from the current time.
+ */
+int timekeeping_inject_offset(struct timespec *ts)
+{
+ unsigned long flags;
+
+ if ((unsigned long)ts->tv_nsec >= NSEC_PER_SEC)
+ return -EINVAL;
+
+ write_seqlock_irqsave(&xtime_lock, flags);
+
+ timekeeping_forward_now();
+
+ xtime = timespec_add(xtime, *ts);
+ wall_to_monotonic = timespec_sub(wall_to_monotonic, *ts);
+
+ timekeeper.ntp_error = 0;
+ ntp_clear();
+
+ update_vsyscall(&xtime, &wall_to_monotonic, timekeeper.clock,
+ timekeeper.mult);
+
+ write_sequnlock_irqrestore(&xtime_lock, flags);
+
+ /* signal hrtimers about time change */
+ clock_was_set();
+
+ return 0;
+}
+EXPORT_SYMBOL(timekeeping_inject_offset);
+
+/**
+ * change_clocksource - Swaps clocksources if a new one is available
+ *
+ * Accumulates current time interval and initializes new clocksource
+ */
+static int change_clocksource(void *data)
+{
+ struct clocksource *new, *old;
+
+ new = (struct clocksource *) data;
+
+ timekeeping_forward_now();
+ if (!new->enable || new->enable(new) == 0) {
+ old = timekeeper.clock;
+ timekeeper_setup_internals(new);
+ if (old->disable)
+ old->disable(old);
+ }
+ return 0;
+}
+
+/**
+ * timekeeping_notify - Install a new clock source
+ * @clock: pointer to the clock source
+ *
+ * This function is called from clocksource.c after a new, better clock
+ * source has been registered. The caller holds the clocksource_mutex.
+ */
+void timekeeping_notify(struct clocksource *clock)
+{
+ if (timekeeper.clock == clock)
+ return;
+ stop_machine(change_clocksource, clock, NULL);
+ tick_clock_notify();
+}
+
+/**
+ * ktime_get_real - get the real (wall-) time in ktime_t format
+ *
+ * returns the time in ktime_t format
+ */
+ktime_t ktime_get_real(void)
+{
+ struct timespec now;
+
+ getnstimeofday(&now);
+
+ return timespec_to_ktime(now);
+}
+EXPORT_SYMBOL_GPL(ktime_get_real);
+
+/**
+ * getrawmonotonic - Returns the raw monotonic time in a timespec
+ * @ts: pointer to the timespec to be set
+ *
+ * Returns the raw monotonic time (completely un-modified by ntp)
+ */
+void getrawmonotonic(struct timespec *ts)
+{
+ unsigned long seq;
+ s64 nsecs;
+
+ do {
+ seq = read_seqbegin(&xtime_lock);
+ nsecs = timekeeping_get_ns_raw();
+ *ts = raw_time;
+
+ } while (read_seqretry(&xtime_lock, seq));
+
+ timespec_add_ns(ts, nsecs);
+}
+EXPORT_SYMBOL(getrawmonotonic);
+
+
+/**
+ * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
+ */
+int timekeeping_valid_for_hres(void)
+{
+ unsigned long seq;
+ int ret;
+
+ do {
+ seq = read_seqbegin(&xtime_lock);
+
+ ret = timekeeper.clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;
+
+ } while (read_seqretry(&xtime_lock, seq));
+
+ return ret;
+}
+
+/**
+ * timekeeping_max_deferment - Returns max time the clocksource can be deferred
+ *
+ * Caller must observe xtime_lock via read_seqbegin/read_seqretry to
+ * ensure that the clocksource does not change!
+ */
+u64 timekeeping_max_deferment(void)
+{
+ return timekeeper.clock->max_idle_ns;
+}
+
+/**
+ * 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);
+
+ write_seqlock_irqsave(&xtime_lock, flags);
+
+ ntp_init();
+
+ clock = clocksource_default_clock();
+ if (clock->enable)
+ clock->enable(clock);
+ timekeeper_setup_internals(clock);
+
+ xtime.tv_sec = now.tv_sec;
+ xtime.tv_nsec = now.tv_nsec;
+ raw_time.tv_sec = 0;
+ raw_time.tv_nsec = 0;
+ if (boot.tv_sec == 0 && boot.tv_nsec == 0) {
+ boot.tv_sec = xtime.tv_sec;
+ boot.tv_nsec = xtime.tv_nsec;
+ }
+ set_normalized_timespec(&wall_to_monotonic,
+ -boot.tv_sec, -boot.tv_nsec);
+ total_sleep_time.tv_sec = 0;
+ total_sleep_time.tv_nsec = 0;
+ write_sequnlock_irqrestore(&xtime_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;
+ }
+
+ xtime = timespec_add(xtime, *delta);
+ wall_to_monotonic = timespec_sub(wall_to_monotonic, *delta);
+ total_sleep_time = timespec_add(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(&xtime_lock, flags);
+ timekeeping_forward_now();
+
+ __timekeeping_inject_sleeptime(delta);
+
+ timekeeper.ntp_error = 0;
+ ntp_clear();
+ update_vsyscall(&xtime, &wall_to_monotonic, timekeeper.clock,
+ timekeeper.mult);
+
+ write_sequnlock_irqrestore(&xtime_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(&xtime_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(&xtime_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(&xtime_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(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(&xtime_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 = 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 then 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 then 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 then 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;
+
+ /*
+ * 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 then 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) {
+ timekeeper.xtime_nsec -= nsecps;
+ xtime.tv_sec++;
+ second_overflow();
+ }
+
+ /* Accumulate raw time */
+ raw_nsecs = timekeeper.raw_interval << shift;
+ raw_nsecs += raw_time.tv_nsec;
+ if (raw_nsecs >= NSEC_PER_SEC) {
+ u64 raw_secs = raw_nsecs;
+ raw_nsecs = do_div(raw_secs, NSEC_PER_SEC);
+ raw_time.tv_sec += raw_secs;
+ }
+ raw_time.tv_nsec = raw_nsecs;
+
+ /* Accumulate error between NTP and clock interval */
+ timekeeper.ntp_error += 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
+ *
+ * Called from the timer interrupt, must hold a write on xtime_lock.
+ */
+static void update_wall_time(void)
+{
+ struct clocksource *clock;
+ cycle_t offset;
+ int shift = 0, maxshift;
+
+ /* Make sure we're fully resumed: */
+ if (unlikely(timekeeping_suspended))
+ return;
+
+ 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)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 then 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 then what overflows tick_length */
+ maxshift = (8*sizeof(tick_length) - (ilog2(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.
+ */
+ xtime.tv_nsec = ((s64) timekeeper.xtime_nsec >> timekeeper.shift) + 1;
+ timekeeper.xtime_nsec -= (s64) 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 then NSEC_PER_SEC
+ */
+ if (unlikely(xtime.tv_nsec >= NSEC_PER_SEC)) {
+ xtime.tv_nsec -= NSEC_PER_SEC;
+ xtime.tv_sec++;
+ second_overflow();
+ }
+
+ /* check to see if there is a new clocksource to use */
+ update_vsyscall(&xtime, &wall_to_monotonic, timekeeper.clock,
+ timekeeper.mult);
+}
+
+/**
+ * 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 = wall_to_monotonic.tv_sec + total_sleep_time.tv_sec,
+ .tv_nsec = wall_to_monotonic.tv_nsec + 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(&xtime_lock);
+ *ts = xtime;
+ tomono = wall_to_monotonic;
+ sleep = total_sleep_time;
+ nsecs = timekeeping_get_ns();
+
+ } while (read_seqretry(&xtime_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, total_sleep_time);
+}
+EXPORT_SYMBOL_GPL(monotonic_to_bootbased);
+
+unsigned long get_seconds(void)
+{
+ return xtime.tv_sec;
+}
+EXPORT_SYMBOL(get_seconds);
+
+struct timespec __current_kernel_time(void)
+{
+ return xtime;
+}
+
+struct timespec current_kernel_time(void)
+{
+ struct timespec now;
+ unsigned long seq;
+
+ do {
+ seq = read_seqbegin(&xtime_lock);
+
+ now = xtime;
+ } while (read_seqretry(&xtime_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(&xtime_lock);
+
+ now = xtime;
+ mono = wall_to_monotonic;
+ } while (read_seqretry(&xtime_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(&xtime_lock);
+ *xtim = xtime;
+ *wtom = wall_to_monotonic;
+ *sleep = total_sleep_time;
+ } while (read_seqretry(&xtime_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(&xtime_lock);
+ wtom = wall_to_monotonic;
+ } while (read_seqretry(&xtime_lock, seq));
+ return timespec_to_ktime(wtom);
+}
+
+/**
+ * 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);
+}