*
* TODO WishList:
* o Allow clocksource drivers to be unregistered
- * o get rid of clocksource_jiffies extern
*/
#include <linux/clocksource.h>
#include <linux/module.h>
#include <linux/sched.h> /* for spin_unlock_irq() using preempt_count() m68k */
#include <linux/tick.h>
+#include <linux/kthread.h>
-/* XXX - Would like a better way for initializing curr_clocksource */
-extern struct clocksource clocksource_jiffies;
+void timecounter_init(struct timecounter *tc,
+ const struct cyclecounter *cc,
+ u64 start_tstamp)
+{
+ tc->cc = cc;
+ tc->cycle_last = cc->read(cc);
+ tc->nsec = start_tstamp;
+}
+EXPORT_SYMBOL_GPL(timecounter_init);
+
+/**
+ * timecounter_read_delta - get nanoseconds since last call of this function
+ * @tc: Pointer to time counter
+ *
+ * When the underlying cycle counter runs over, this will be handled
+ * correctly as long as it does not run over more than once between
+ * calls.
+ *
+ * The first call to this function for a new time counter initializes
+ * the time tracking and returns an undefined result.
+ */
+static u64 timecounter_read_delta(struct timecounter *tc)
+{
+ cycle_t cycle_now, cycle_delta;
+ u64 ns_offset;
+
+ /* read cycle counter: */
+ cycle_now = tc->cc->read(tc->cc);
+
+ /* calculate the delta since the last timecounter_read_delta(): */
+ cycle_delta = (cycle_now - tc->cycle_last) & tc->cc->mask;
+
+ /* convert to nanoseconds: */
+ ns_offset = cyclecounter_cyc2ns(tc->cc, cycle_delta);
+
+ /* update time stamp of timecounter_read_delta() call: */
+ tc->cycle_last = cycle_now;
+
+ return ns_offset;
+}
+
+u64 timecounter_read(struct timecounter *tc)
+{
+ u64 nsec;
+
+ /* increment time by nanoseconds since last call */
+ nsec = timecounter_read_delta(tc);
+ nsec += tc->nsec;
+ tc->nsec = nsec;
+
+ return nsec;
+}
+EXPORT_SYMBOL_GPL(timecounter_read);
+
+u64 timecounter_cyc2time(struct timecounter *tc,
+ cycle_t cycle_tstamp)
+{
+ u64 cycle_delta = (cycle_tstamp - tc->cycle_last) & tc->cc->mask;
+ u64 nsec;
+
+ /*
+ * Instead of always treating cycle_tstamp as more recent
+ * than tc->cycle_last, detect when it is too far in the
+ * future and treat it as old time stamp instead.
+ */
+ if (cycle_delta > tc->cc->mask / 2) {
+ cycle_delta = (tc->cycle_last - cycle_tstamp) & tc->cc->mask;
+ nsec = tc->nsec - cyclecounter_cyc2ns(tc->cc, cycle_delta);
+ } else {
+ nsec = cyclecounter_cyc2ns(tc->cc, cycle_delta) + tc->nsec;
+ }
+
+ return nsec;
+}
+EXPORT_SYMBOL_GPL(timecounter_cyc2time);
+
+/**
+ * clocks_calc_mult_shift - calculate mult/shift factors for scaled math of clocks
+ * @mult: pointer to mult variable
+ * @shift: pointer to shift variable
+ * @from: frequency to convert from
+ * @to: frequency to convert to
+ * @minsec: guaranteed runtime conversion range in seconds
+ *
+ * The function evaluates the shift/mult pair for the scaled math
+ * operations of clocksources and clockevents.
+ *
+ * @to and @from are frequency values in HZ. For clock sources @to is
+ * NSEC_PER_SEC == 1GHz and @from is the counter frequency. For clock
+ * event @to is the counter frequency and @from is NSEC_PER_SEC.
+ *
+ * The @minsec conversion range argument controls the time frame in
+ * seconds which must be covered by the runtime conversion with the
+ * calculated mult and shift factors. This guarantees that no 64bit
+ * overflow happens when the input value of the conversion is
+ * multiplied with the calculated mult factor. Larger ranges may
+ * reduce the conversion accuracy by chosing smaller mult and shift
+ * factors.
+ */
+void
+clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec)
+{
+ u64 tmp;
+ u32 sft, sftacc= 32;
+
+ /*
+ * Calculate the shift factor which is limiting the conversion
+ * range:
+ */
+ tmp = ((u64)minsec * from) >> 32;
+ while (tmp) {
+ tmp >>=1;
+ sftacc--;
+ }
+
+ /*
+ * Find the conversion shift/mult pair which has the best
+ * accuracy and fits the maxsec conversion range:
+ */
+ for (sft = 32; sft > 0; sft--) {
+ tmp = (u64) to << sft;
+ do_div(tmp, from);
+ if ((tmp >> sftacc) == 0)
+ break;
+ }
+ *mult = tmp;
+ *shift = sft;
+}
/*[Clocksource internal variables]---------
* curr_clocksource:
- * currently selected clocksource. Initialized to clocksource_jiffies.
- * next_clocksource:
- * pending next selected clocksource.
+ * currently selected clocksource.
* clocksource_list:
* linked list with the registered clocksources
- * clocksource_lock:
- * protects manipulations to curr_clocksource and next_clocksource
- * and the clocksource_list
+ * clocksource_mutex:
+ * protects manipulations to curr_clocksource and the clocksource_list
* override_name:
* Name of the user-specified clocksource.
*/
-static struct clocksource *curr_clocksource = &clocksource_jiffies;
-static struct clocksource *next_clocksource;
-static struct clocksource *clocksource_override;
+static struct clocksource *curr_clocksource;
static LIST_HEAD(clocksource_list);
-static DEFINE_SPINLOCK(clocksource_lock);
+static DEFINE_MUTEX(clocksource_mutex);
static char override_name[32];
static int finished_booting;
-/* clocksource_done_booting - Called near the end of core bootup
- *
- * Hack to avoid lots of clocksource churn at boot time.
- * We use fs_initcall because we want this to start before
- * device_initcall but after subsys_initcall.
- */
-static int __init clocksource_done_booting(void)
-{
- finished_booting = 1;
- return 0;
-}
-fs_initcall(clocksource_done_booting);
-
#ifdef CONFIG_CLOCKSOURCE_WATCHDOG
+static void clocksource_watchdog_work(struct work_struct *work);
+
static LIST_HEAD(watchdog_list);
static struct clocksource *watchdog;
static struct timer_list watchdog_timer;
+static DECLARE_WORK(watchdog_work, clocksource_watchdog_work);
static DEFINE_SPINLOCK(watchdog_lock);
static cycle_t watchdog_last;
-static unsigned long watchdog_resumed;
+static int watchdog_running;
+
+static int clocksource_watchdog_kthread(void *data);
+static void __clocksource_change_rating(struct clocksource *cs, int rating);
/*
* Interval: 0.5sec Threshold: 0.0625s
#define WATCHDOG_INTERVAL (HZ >> 1)
#define WATCHDOG_THRESHOLD (NSEC_PER_SEC >> 4)
-static void clocksource_ratewd(struct clocksource *cs, int64_t delta)
+static void clocksource_watchdog_work(struct work_struct *work)
{
- if (delta > -WATCHDOG_THRESHOLD && delta < WATCHDOG_THRESHOLD)
- return;
+ /*
+ * If kthread_run fails the next watchdog scan over the
+ * watchdog_list will find the unstable clock again.
+ */
+ kthread_run(clocksource_watchdog_kthread, NULL, "kwatchdog");
+}
+static void __clocksource_unstable(struct clocksource *cs)
+{
+ cs->flags &= ~(CLOCK_SOURCE_VALID_FOR_HRES | CLOCK_SOURCE_WATCHDOG);
+ cs->flags |= CLOCK_SOURCE_UNSTABLE;
+ if (finished_booting)
+ schedule_work(&watchdog_work);
+}
+
+static void clocksource_unstable(struct clocksource *cs, int64_t delta)
+{
printk(KERN_WARNING "Clocksource %s unstable (delta = %Ld ns)\n",
cs->name, delta);
- cs->flags &= ~(CLOCK_SOURCE_VALID_FOR_HRES | CLOCK_SOURCE_WATCHDOG);
- clocksource_change_rating(cs, 0);
- list_del(&cs->wd_list);
+ __clocksource_unstable(cs);
+}
+
+/**
+ * clocksource_mark_unstable - mark clocksource unstable via watchdog
+ * @cs: clocksource to be marked unstable
+ *
+ * This function is called instead of clocksource_change_rating from
+ * cpu hotplug code to avoid a deadlock between the clocksource mutex
+ * and the cpu hotplug mutex. It defers the update of the clocksource
+ * to the watchdog thread.
+ */
+void clocksource_mark_unstable(struct clocksource *cs)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&watchdog_lock, flags);
+ if (!(cs->flags & CLOCK_SOURCE_UNSTABLE)) {
+ if (list_empty(&cs->wd_list))
+ list_add(&cs->wd_list, &watchdog_list);
+ __clocksource_unstable(cs);
+ }
+ spin_unlock_irqrestore(&watchdog_lock, flags);
}
static void clocksource_watchdog(unsigned long data)
{
- struct clocksource *cs, *tmp;
+ struct clocksource *cs;
cycle_t csnow, wdnow;
int64_t wd_nsec, cs_nsec;
- int resumed;
+ int next_cpu;
spin_lock(&watchdog_lock);
+ if (!watchdog_running)
+ goto out;
- resumed = test_and_clear_bit(0, &watchdog_resumed);
-
- wdnow = watchdog->read();
- wd_nsec = cyc2ns(watchdog, (wdnow - watchdog_last) & watchdog->mask);
+ wdnow = watchdog->read(watchdog);
+ wd_nsec = clocksource_cyc2ns((wdnow - watchdog_last) & watchdog->mask,
+ watchdog->mult, watchdog->shift);
watchdog_last = wdnow;
- list_for_each_entry_safe(cs, tmp, &watchdog_list, wd_list) {
- csnow = cs->read();
+ list_for_each_entry(cs, &watchdog_list, wd_list) {
- if (unlikely(resumed)) {
- cs->wd_last = csnow;
+ /* Clocksource already marked unstable? */
+ if (cs->flags & CLOCK_SOURCE_UNSTABLE) {
+ if (finished_booting)
+ schedule_work(&watchdog_work);
continue;
}
- /* Initialized ? */
+ csnow = cs->read(cs);
+
+ /* Clocksource initialized ? */
if (!(cs->flags & CLOCK_SOURCE_WATCHDOG)) {
- if ((cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) &&
- (watchdog->flags & CLOCK_SOURCE_IS_CONTINUOUS)) {
- cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES;
- /*
- * We just marked the clocksource as
- * highres-capable, notify the rest of the
- * system as well so that we transition
- * into high-res mode:
- */
- tick_clock_notify();
- }
cs->flags |= CLOCK_SOURCE_WATCHDOG;
cs->wd_last = csnow;
- } else {
- cs_nsec = cyc2ns(cs, (csnow - cs->wd_last) & cs->mask);
- cs->wd_last = csnow;
- /* Check the delta. Might remove from the list ! */
- clocksource_ratewd(cs, cs_nsec - wd_nsec);
+ continue;
}
- }
- if (!list_empty(&watchdog_list)) {
- /*
- * Cycle through CPUs to check if the CPUs stay
- * synchronized to each other.
- */
- int next_cpu = next_cpu(raw_smp_processor_id(), cpu_online_map);
+ /* Check the deviation from the watchdog clocksource. */
+ cs_nsec = clocksource_cyc2ns((csnow - cs->wd_last) &
+ cs->mask, cs->mult, cs->shift);
+ cs->wd_last = csnow;
+ if (abs(cs_nsec - wd_nsec) > WATCHDOG_THRESHOLD) {
+ clocksource_unstable(cs, cs_nsec - wd_nsec);
+ continue;
+ }
- if (next_cpu >= NR_CPUS)
- next_cpu = first_cpu(cpu_online_map);
- watchdog_timer.expires += WATCHDOG_INTERVAL;
- add_timer_on(&watchdog_timer, next_cpu);
+ if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) &&
+ (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) &&
+ (watchdog->flags & CLOCK_SOURCE_IS_CONTINUOUS)) {
+ cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES;
+ /*
+ * We just marked the clocksource as highres-capable,
+ * notify the rest of the system as well so that we
+ * transition into high-res mode:
+ */
+ tick_clock_notify();
+ }
}
+
+ /*
+ * Cycle through CPUs to check if the CPUs stay synchronized
+ * to each other.
+ */
+ next_cpu = cpumask_next(raw_smp_processor_id(), cpu_online_mask);
+ if (next_cpu >= nr_cpu_ids)
+ next_cpu = cpumask_first(cpu_online_mask);
+ watchdog_timer.expires += WATCHDOG_INTERVAL;
+ add_timer_on(&watchdog_timer, next_cpu);
+out:
spin_unlock(&watchdog_lock);
}
+
+static inline void clocksource_start_watchdog(void)
+{
+ if (watchdog_running || !watchdog || list_empty(&watchdog_list))
+ return;
+ init_timer(&watchdog_timer);
+ watchdog_timer.function = clocksource_watchdog;
+ watchdog_last = watchdog->read(watchdog);
+ watchdog_timer.expires = jiffies + WATCHDOG_INTERVAL;
+ add_timer_on(&watchdog_timer, cpumask_first(cpu_online_mask));
+ watchdog_running = 1;
+}
+
+static inline void clocksource_stop_watchdog(void)
+{
+ if (!watchdog_running || (watchdog && !list_empty(&watchdog_list)))
+ return;
+ del_timer(&watchdog_timer);
+ watchdog_running = 0;
+}
+
+static inline void clocksource_reset_watchdog(void)
+{
+ struct clocksource *cs;
+
+ list_for_each_entry(cs, &watchdog_list, wd_list)
+ cs->flags &= ~CLOCK_SOURCE_WATCHDOG;
+}
+
static void clocksource_resume_watchdog(void)
{
- set_bit(0, &watchdog_resumed);
+ unsigned long flags;
+
+ /*
+ * We use trylock here to avoid a potential dead lock when
+ * kgdb calls this code after the kernel has been stopped with
+ * watchdog_lock held. When watchdog_lock is held we just
+ * return and accept, that the watchdog might trigger and mark
+ * the monitored clock source (usually TSC) unstable.
+ *
+ * This does not affect the other caller clocksource_resume()
+ * because at this point the kernel is UP, interrupts are
+ * disabled and nothing can hold watchdog_lock.
+ */
+ if (!spin_trylock_irqsave(&watchdog_lock, flags))
+ return;
+ clocksource_reset_watchdog();
+ spin_unlock_irqrestore(&watchdog_lock, flags);
}
-static void clocksource_check_watchdog(struct clocksource *cs)
+static void clocksource_enqueue_watchdog(struct clocksource *cs)
{
- struct clocksource *cse;
unsigned long flags;
spin_lock_irqsave(&watchdog_lock, flags);
if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) {
- int started = !list_empty(&watchdog_list);
-
+ /* cs is a clocksource to be watched. */
list_add(&cs->wd_list, &watchdog_list);
- if (!started && watchdog) {
- watchdog_last = watchdog->read();
- watchdog_timer.expires = jiffies + WATCHDOG_INTERVAL;
- add_timer_on(&watchdog_timer,
- first_cpu(cpu_online_map));
- }
+ cs->flags &= ~CLOCK_SOURCE_WATCHDOG;
} else {
+ /* cs is a watchdog. */
if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS)
cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES;
-
+ /* Pick the best watchdog. */
if (!watchdog || cs->rating > watchdog->rating) {
- if (watchdog)
- del_timer(&watchdog_timer);
watchdog = cs;
- init_timer(&watchdog_timer);
- watchdog_timer.function = clocksource_watchdog;
-
/* Reset watchdog cycles */
- list_for_each_entry(cse, &watchdog_list, wd_list)
- cse->flags &= ~CLOCK_SOURCE_WATCHDOG;
- /* Start if list is not empty */
- if (!list_empty(&watchdog_list)) {
- watchdog_last = watchdog->read();
- watchdog_timer.expires =
- jiffies + WATCHDOG_INTERVAL;
- add_timer_on(&watchdog_timer,
- first_cpu(cpu_online_map));
- }
+ clocksource_reset_watchdog();
}
}
+ /* Check if the watchdog timer needs to be started. */
+ clocksource_start_watchdog();
+ spin_unlock_irqrestore(&watchdog_lock, flags);
+}
+
+static void clocksource_dequeue_watchdog(struct clocksource *cs)
+{
+ struct clocksource *tmp;
+ unsigned long flags;
+
+ spin_lock_irqsave(&watchdog_lock, flags);
+ if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) {
+ /* cs is a watched clocksource. */
+ list_del_init(&cs->wd_list);
+ } else if (cs == watchdog) {
+ /* Reset watchdog cycles */
+ clocksource_reset_watchdog();
+ /* Current watchdog is removed. Find an alternative. */
+ watchdog = NULL;
+ list_for_each_entry(tmp, &clocksource_list, list) {
+ if (tmp == cs || tmp->flags & CLOCK_SOURCE_MUST_VERIFY)
+ continue;
+ if (!watchdog || tmp->rating > watchdog->rating)
+ watchdog = tmp;
+ }
+ }
+ cs->flags &= ~CLOCK_SOURCE_WATCHDOG;
+ /* Check if the watchdog timer needs to be stopped. */
+ clocksource_stop_watchdog();
+ spin_unlock_irqrestore(&watchdog_lock, flags);
+}
+
+static int clocksource_watchdog_kthread(void *data)
+{
+ struct clocksource *cs, *tmp;
+ unsigned long flags;
+ LIST_HEAD(unstable);
+
+ mutex_lock(&clocksource_mutex);
+ spin_lock_irqsave(&watchdog_lock, flags);
+ list_for_each_entry_safe(cs, tmp, &watchdog_list, wd_list)
+ if (cs->flags & CLOCK_SOURCE_UNSTABLE) {
+ list_del_init(&cs->wd_list);
+ list_add(&cs->wd_list, &unstable);
+ }
+ /* Check if the watchdog timer needs to be stopped. */
+ clocksource_stop_watchdog();
spin_unlock_irqrestore(&watchdog_lock, flags);
+
+ /* Needs to be done outside of watchdog lock */
+ list_for_each_entry_safe(cs, tmp, &unstable, wd_list) {
+ list_del_init(&cs->wd_list);
+ __clocksource_change_rating(cs, 0);
+ }
+ mutex_unlock(&clocksource_mutex);
+ return 0;
}
-#else
-static void clocksource_check_watchdog(struct clocksource *cs)
+
+#else /* CONFIG_CLOCKSOURCE_WATCHDOG */
+
+static void clocksource_enqueue_watchdog(struct clocksource *cs)
{
if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS)
cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES;
}
+static inline void clocksource_dequeue_watchdog(struct clocksource *cs) { }
static inline void clocksource_resume_watchdog(void) { }
-#endif
+static inline int clocksource_watchdog_kthread(void *data) { return 0; }
+
+#endif /* CONFIG_CLOCKSOURCE_WATCHDOG */
+
+/**
+ * clocksource_suspend - suspend the clocksource(s)
+ */
+void clocksource_suspend(void)
+{
+ struct clocksource *cs;
+
+ list_for_each_entry_reverse(cs, &clocksource_list, list)
+ if (cs->suspend)
+ cs->suspend(cs);
+}
/**
* clocksource_resume - resume the clocksource(s)
void clocksource_resume(void)
{
struct clocksource *cs;
- unsigned long flags;
- spin_lock_irqsave(&clocksource_lock, flags);
-
- list_for_each_entry(cs, &clocksource_list, list) {
+ list_for_each_entry(cs, &clocksource_list, list)
if (cs->resume)
- cs->resume();
- }
+ cs->resume(cs);
clocksource_resume_watchdog();
-
- spin_unlock_irqrestore(&clocksource_lock, flags);
}
/**
* clocksource_touch_watchdog - Update watchdog
*
* Update the watchdog after exception contexts such as kgdb so as not
- * to incorrectly trip the watchdog.
- *
+ * to incorrectly trip the watchdog. This might fail when the kernel
+ * was stopped in code which holds watchdog_lock.
*/
void clocksource_touch_watchdog(void)
{
}
/**
- * clocksource_get_next - Returns the selected clocksource
+ * clocksource_max_deferment - Returns max time the clocksource can be deferred
+ * @cs: Pointer to clocksource
*
*/
-struct clocksource *clocksource_get_next(void)
+static u64 clocksource_max_deferment(struct clocksource *cs)
{
- unsigned long flags;
-
- spin_lock_irqsave(&clocksource_lock, flags);
- if (next_clocksource && finished_booting) {
- curr_clocksource = next_clocksource;
- next_clocksource = NULL;
- }
- spin_unlock_irqrestore(&clocksource_lock, flags);
-
- return curr_clocksource;
+ u64 max_nsecs, max_cycles;
+
+ /*
+ * Calculate the maximum number of cycles that we can pass to the
+ * cyc2ns function without overflowing a 64-bit signed result. The
+ * maximum number of cycles is equal to ULLONG_MAX/cs->mult which
+ * is equivalent to the below.
+ * max_cycles < (2^63)/cs->mult
+ * max_cycles < 2^(log2((2^63)/cs->mult))
+ * max_cycles < 2^(log2(2^63) - log2(cs->mult))
+ * max_cycles < 2^(63 - log2(cs->mult))
+ * max_cycles < 1 << (63 - log2(cs->mult))
+ * Please note that we add 1 to the result of the log2 to account for
+ * any rounding errors, ensure the above inequality is satisfied and
+ * no overflow will occur.
+ */
+ max_cycles = 1ULL << (63 - (ilog2(cs->mult) + 1));
+
+ /*
+ * The actual maximum number of cycles we can defer the clocksource is
+ * determined by the minimum of max_cycles and cs->mask.
+ */
+ max_cycles = min_t(u64, max_cycles, (u64) cs->mask);
+ max_nsecs = clocksource_cyc2ns(max_cycles, cs->mult, cs->shift);
+
+ /*
+ * To ensure that the clocksource does not wrap whilst we are idle,
+ * limit the time the clocksource can be deferred by 12.5%. Please
+ * note a margin of 12.5% is used because this can be computed with
+ * a shift, versus say 10% which would require division.
+ */
+ return max_nsecs - (max_nsecs >> 5);
}
+#ifdef CONFIG_GENERIC_TIME
+
/**
- * select_clocksource - Selects the best registered clocksource.
+ * clocksource_select - Select the best clocksource available
*
- * Private function. Must hold clocksource_lock when called.
+ * Private function. Must hold clocksource_mutex when called.
*
* Select the clocksource with the best rating, or the clocksource,
* which is selected by userspace override.
*/
-static struct clocksource *select_clocksource(void)
+static void clocksource_select(void)
{
- struct clocksource *next;
+ struct clocksource *best, *cs;
- if (list_empty(&clocksource_list))
- return NULL;
+ if (!finished_booting || list_empty(&clocksource_list))
+ return;
+ /* First clocksource on the list has the best rating. */
+ best = list_first_entry(&clocksource_list, struct clocksource, list);
+ /* Check for the override clocksource. */
+ list_for_each_entry(cs, &clocksource_list, list) {
+ if (strcmp(cs->name, override_name) != 0)
+ continue;
+ /*
+ * Check to make sure we don't switch to a non-highres
+ * capable clocksource if the tick code is in oneshot
+ * mode (highres or nohz)
+ */
+ if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) &&
+ tick_oneshot_mode_active()) {
+ /* Override clocksource cannot be used. */
+ printk(KERN_WARNING "Override clocksource %s is not "
+ "HRT compatible. Cannot switch while in "
+ "HRT/NOHZ mode\n", cs->name);
+ override_name[0] = 0;
+ } else
+ /* Override clocksource can be used. */
+ best = cs;
+ break;
+ }
+ if (curr_clocksource != best) {
+ printk(KERN_INFO "Switching to clocksource %s\n", best->name);
+ curr_clocksource = best;
+ timekeeping_notify(curr_clocksource);
+ }
+}
- if (clocksource_override)
- next = clocksource_override;
- else
- next = list_entry(clocksource_list.next, struct clocksource,
- list);
+#else /* CONFIG_GENERIC_TIME */
- if (next == curr_clocksource)
- return NULL;
+static inline void clocksource_select(void) { }
- return next;
-}
+#endif
/*
- * Enqueue the clocksource sorted by rating
+ * clocksource_done_booting - Called near the end of core bootup
+ *
+ * Hack to avoid lots of clocksource churn at boot time.
+ * We use fs_initcall because we want this to start before
+ * device_initcall but after subsys_initcall.
*/
-static int clocksource_enqueue(struct clocksource *c)
+static int __init clocksource_done_booting(void)
{
- struct list_head *tmp, *entry = &clocksource_list;
+ mutex_lock(&clocksource_mutex);
+ curr_clocksource = clocksource_default_clock();
+ mutex_unlock(&clocksource_mutex);
- list_for_each(tmp, &clocksource_list) {
- struct clocksource *cs;
-
- cs = list_entry(tmp, struct clocksource, list);
- if (cs == c)
- return -EBUSY;
- /* Keep track of the place, where to insert */
- if (cs->rating >= c->rating)
- entry = tmp;
- }
- list_add(&c->list, entry);
+ finished_booting = 1;
- if (strlen(c->name) == strlen(override_name) &&
- !strcmp(c->name, override_name))
- clocksource_override = c;
+ /*
+ * Run the watchdog first to eliminate unstable clock sources
+ */
+ clocksource_watchdog_kthread(NULL);
+ mutex_lock(&clocksource_mutex);
+ clocksource_select();
+ mutex_unlock(&clocksource_mutex);
return 0;
}
+fs_initcall(clocksource_done_booting);
+
+/*
+ * Enqueue the clocksource sorted by rating
+ */
+static void clocksource_enqueue(struct clocksource *cs)
+{
+ struct list_head *entry = &clocksource_list;
+ struct clocksource *tmp;
+
+ list_for_each_entry(tmp, &clocksource_list, list)
+ /* Keep track of the place, where to insert */
+ if (tmp->rating >= cs->rating)
+ entry = &tmp->list;
+ list_add(&cs->list, entry);
+}
/**
* clocksource_register - Used to install new clocksources
*
* Returns -EBUSY if registration fails, zero otherwise.
*/
-int clocksource_register(struct clocksource *c)
+int clocksource_register(struct clocksource *cs)
{
- unsigned long flags;
- int ret;
-
- spin_lock_irqsave(&clocksource_lock, flags);
- ret = clocksource_enqueue(c);
- if (!ret)
- next_clocksource = select_clocksource();
- spin_unlock_irqrestore(&clocksource_lock, flags);
- if (!ret)
- clocksource_check_watchdog(c);
- return ret;
+ /* calculate max idle time permitted for this clocksource */
+ cs->max_idle_ns = clocksource_max_deferment(cs);
+
+ mutex_lock(&clocksource_mutex);
+ clocksource_enqueue(cs);
+ clocksource_select();
+ clocksource_enqueue_watchdog(cs);
+ mutex_unlock(&clocksource_mutex);
+ return 0;
}
EXPORT_SYMBOL(clocksource_register);
+static void __clocksource_change_rating(struct clocksource *cs, int rating)
+{
+ list_del(&cs->list);
+ cs->rating = rating;
+ clocksource_enqueue(cs);
+ clocksource_select();
+}
+
/**
* clocksource_change_rating - Change the rating of a registered clocksource
- *
*/
void clocksource_change_rating(struct clocksource *cs, int rating)
{
- unsigned long flags;
-
- spin_lock_irqsave(&clocksource_lock, flags);
- list_del(&cs->list);
- cs->rating = rating;
- clocksource_enqueue(cs);
- next_clocksource = select_clocksource();
- spin_unlock_irqrestore(&clocksource_lock, flags);
+ mutex_lock(&clocksource_mutex);
+ __clocksource_change_rating(cs, rating);
+ mutex_unlock(&clocksource_mutex);
}
+EXPORT_SYMBOL(clocksource_change_rating);
/**
* clocksource_unregister - remove a registered clocksource
*/
void clocksource_unregister(struct clocksource *cs)
{
- unsigned long flags;
-
- spin_lock_irqsave(&clocksource_lock, flags);
+ mutex_lock(&clocksource_mutex);
+ clocksource_dequeue_watchdog(cs);
list_del(&cs->list);
- if (clocksource_override == cs)
- clocksource_override = NULL;
- next_clocksource = select_clocksource();
- spin_unlock_irqrestore(&clocksource_lock, flags);
+ clocksource_select();
+ mutex_unlock(&clocksource_mutex);
}
+EXPORT_SYMBOL(clocksource_unregister);
#ifdef CONFIG_SYSFS
/**
{
ssize_t count = 0;
- spin_lock_irq(&clocksource_lock);
+ mutex_lock(&clocksource_mutex);
count = snprintf(buf, PAGE_SIZE, "%s\n", curr_clocksource->name);
- spin_unlock_irq(&clocksource_lock);
+ mutex_unlock(&clocksource_mutex);
return count;
}
* @count: length of buffer
*
* Takes input from sysfs interface for manually overriding the default
- * clocksource selction.
+ * clocksource selection.
*/
static ssize_t sysfs_override_clocksource(struct sys_device *dev,
struct sysdev_attribute *attr,
const char *buf, size_t count)
{
- struct clocksource *ovr = NULL;
size_t ret = count;
- int len;
/* strings from sysfs write are not 0 terminated! */
if (count >= sizeof(override_name))
if (buf[count-1] == '\n')
count--;
- spin_lock_irq(&clocksource_lock);
+ mutex_lock(&clocksource_mutex);
if (count > 0)
memcpy(override_name, buf, count);
override_name[count] = 0;
+ clocksource_select();
- len = strlen(override_name);
- if (len) {
- struct clocksource *cs;
-
- ovr = clocksource_override;
- /* try to select it: */
- list_for_each_entry(cs, &clocksource_list, list) {
- if (strlen(cs->name) == len &&
- !strcmp(cs->name, override_name))
- ovr = cs;
- }
- }
-
- /* Reselect, when the override name has changed */
- if (ovr != clocksource_override) {
- clocksource_override = ovr;
- next_clocksource = select_clocksource();
- }
-
- spin_unlock_irq(&clocksource_lock);
+ mutex_unlock(&clocksource_mutex);
return ret;
}
struct clocksource *src;
ssize_t count = 0;
- spin_lock_irq(&clocksource_lock);
+ mutex_lock(&clocksource_mutex);
list_for_each_entry(src, &clocksource_list, list) {
- count += snprintf(buf + count,
+ /*
+ * Don't show non-HRES clocksource if the tick code is
+ * in one shot mode (highres=on or nohz=on)
+ */
+ if (!tick_oneshot_mode_active() ||
+ (src->flags & CLOCK_SOURCE_VALID_FOR_HRES))
+ count += snprintf(buf + count,
max((ssize_t)PAGE_SIZE - count, (ssize_t)0),
"%s ", src->name);
}
- spin_unlock_irq(&clocksource_lock);
+ mutex_unlock(&clocksource_mutex);
count += snprintf(buf + count,
max((ssize_t)PAGE_SIZE - count, (ssize_t)0), "\n");
*/
static int __init boot_override_clocksource(char* str)
{
- unsigned long flags;
- spin_lock_irqsave(&clocksource_lock, flags);
+ mutex_lock(&clocksource_mutex);
if (str)
strlcpy(override_name, str, sizeof(override_name));
- spin_unlock_irqrestore(&clocksource_lock, flags);
+ mutex_unlock(&clocksource_mutex);
return 1;
}
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff