#include <linux/init.h>
#include <linux/module.h>
#include <linux/sched.h> /* for spin_unlock_irq() using preempt_count() m68k */
+#include <linux/tick.h>
/* XXX - Would like a better way for initializing curr_clocksource */
extern struct clocksource clocksource_jiffies;
*/
static struct clocksource *curr_clocksource = &clocksource_jiffies;
static struct clocksource *next_clocksource;
+static struct clocksource *clocksource_override;
static LIST_HEAD(clocksource_list);
static DEFINE_SPINLOCK(clocksource_lock);
static char override_name[32];
static int finished_booting;
-/* clocksource_done_booting - Called near the end of bootup
+/* clocksource_done_booting - Called near the end of core bootup
*
- * Hack to avoid lots of clocksource churn at boot time
+ * 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 LIST_HEAD(watchdog_list);
+static struct clocksource *watchdog;
+static struct timer_list watchdog_timer;
+static DEFINE_SPINLOCK(watchdog_lock);
+static cycle_t watchdog_last;
+/*
+ * Interval: 0.5sec Treshold: 0.0625s
+ */
+#define WATCHDOG_INTERVAL (HZ >> 1)
+#define WATCHDOG_TRESHOLD (NSEC_PER_SEC >> 4)
-late_initcall(clocksource_done_booting);
+static void clocksource_ratewd(struct clocksource *cs, int64_t delta)
+{
+ if (delta > -WATCHDOG_TRESHOLD && delta < WATCHDOG_TRESHOLD)
+ return;
+
+ 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);
+ cs->flags &= ~CLOCK_SOURCE_WATCHDOG;
+ list_del(&cs->wd_list);
+}
+
+static void clocksource_watchdog(unsigned long data)
+{
+ struct clocksource *cs, *tmp;
+ cycle_t csnow, wdnow;
+ int64_t wd_nsec, cs_nsec;
+
+ spin_lock(&watchdog_lock);
+
+ wdnow = watchdog->read();
+ wd_nsec = cyc2ns(watchdog, (wdnow - watchdog_last) & watchdog->mask);
+ watchdog_last = wdnow;
+
+ list_for_each_entry_safe(cs, tmp, &watchdog_list, wd_list) {
+ csnow = cs->read();
+ /* 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);
+ }
+ }
+
+ if (!list_empty(&watchdog_list)) {
+ __mod_timer(&watchdog_timer,
+ watchdog_timer.expires + WATCHDOG_INTERVAL);
+ }
+ spin_unlock(&watchdog_lock);
+}
+static void clocksource_check_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);
+
+ list_add(&cs->wd_list, &watchdog_list);
+ if (!started && watchdog) {
+ watchdog_last = watchdog->read();
+ watchdog_timer.expires = jiffies + WATCHDOG_INTERVAL;
+ add_timer(&watchdog_timer);
+ }
+ } else {
+ if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS)
+ cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES;
+
+ 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(&watchdog_timer);
+ }
+ }
+ }
+ spin_unlock_irqrestore(&watchdog_lock, flags);
+}
+#else
+static void clocksource_check_watchdog(struct clocksource *cs)
+{
+ if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS)
+ cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES;
+}
+#endif
/**
* clocksource_get_next - Returns the selected clocksource
}
/**
- * select_clocksource - Finds the best registered clocksource.
+ * select_clocksource - Selects the best registered clocksource.
*
* Private function. Must hold clocksource_lock when called.
*
- * Looks through the list of registered clocksources, returning
- * the one with the highest rating value. If there is a clocksource
- * name that matches the override string, it returns that clocksource.
+ * Select the clocksource with the best rating, or the clocksource,
+ * which is selected by userspace override.
*/
static struct clocksource *select_clocksource(void)
{
- struct clocksource *best = NULL;
- struct list_head *tmp;
+ struct clocksource *next;
- list_for_each(tmp, &clocksource_list) {
- struct clocksource *src;
+ if (list_empty(&clocksource_list))
+ return NULL;
- src = list_entry(tmp, struct clocksource, list);
- if (!best)
- best = src;
-
- /* check for override: */
- if (strlen(src->name) == strlen(override_name) &&
- !strcmp(src->name, override_name)) {
- best = src;
- break;
- }
- /* pick the highest rating: */
- if (src->rating > best->rating)
- best = src;
- }
+ if (clocksource_override)
+ next = clocksource_override;
+ else
+ next = list_entry(clocksource_list.next, struct clocksource,
+ list);
- return best;
+ if (next == curr_clocksource)
+ return NULL;
+
+ return next;
}
-/**
- * is_registered_source - Checks if clocksource is registered
- * @c: pointer to a clocksource
- *
- * Private helper function. Must hold clocksource_lock when called.
- *
- * Returns one if the clocksource is already registered, zero otherwise.
+/*
+ * Enqueue the clocksource sorted by rating
*/
-static int is_registered_source(struct clocksource *c)
+static int clocksource_enqueue(struct clocksource *c)
{
- int len = strlen(c->name);
- struct list_head *tmp;
+ struct list_head *tmp, *entry = &clocksource_list;
list_for_each(tmp, &clocksource_list) {
- struct clocksource *src;
-
- src = list_entry(tmp, struct clocksource, list);
- if (strlen(src->name) == len && !strcmp(src->name, c->name))
- return 1;
+ 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);
+
+ if (strlen(c->name) == strlen(override_name) &&
+ !strcmp(c->name, override_name))
+ clocksource_override = c;
return 0;
}
*/
int clocksource_register(struct clocksource *c)
{
- int ret = 0;
unsigned long flags;
+ int ret;
spin_lock_irqsave(&clocksource_lock, flags);
- /* check if clocksource is already registered */
- if (is_registered_source(c)) {
- printk("register_clocksource: Cannot register %s. "
- "Already registered!", c->name);
- ret = -EBUSY;
- } else {
- /* register it */
- list_add(&c->list, &clocksource_list);
- /* scan the registered clocksources, and pick the best one */
+ ret = clocksource_enqueue(c);
+ if (!ret)
next_clocksource = select_clocksource();
- }
spin_unlock_irqrestore(&clocksource_lock, flags);
+ if (!ret)
+ clocksource_check_watchdog(c);
return ret;
}
EXPORT_SYMBOL(clocksource_register);
/**
- * clocksource_reselect - Rescan list for next clocksource
+ * clocksource_change_rating - Change the rating of a registered clocksource
*
- * A quick helper function to be used if a clocksource changes its
- * rating. Forces the clocksource list to be re-scanned for the best
- * clocksource.
*/
-void clocksource_reselect(void)
+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);
}
-EXPORT_SYMBOL(clocksource_reselect);
#ifdef CONFIG_SYSFS
/**
static ssize_t sysfs_override_clocksource(struct sys_device *dev,
const char *buf, size_t count)
{
+ struct clocksource *ovr = NULL;
+ struct list_head *tmp;
size_t ret = count;
+ int len;
+
/* strings from sysfs write are not 0 terminated! */
if (count >= sizeof(override_name))
return -EINVAL;
/* strip of \n: */
if (buf[count-1] == '\n')
count--;
- if (count < 1)
- return -EINVAL;
spin_lock_irq(&clocksource_lock);
- /* copy the name given: */
- memcpy(override_name, buf, count);
+ if (count > 0)
+ memcpy(override_name, buf, count);
override_name[count] = 0;
- /* try to select it: */
- next_clocksource = select_clocksource();
+ len = strlen(override_name);
+ if (len) {
+ ovr = clocksource_override;
+ /* try to select it: */
+ list_for_each(tmp, &clocksource_list) {
+ struct clocksource *cs;
+
+ cs = list_entry(tmp, struct clocksource, 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);
projects / powerpc.git / blobdiff