summaryrefslogtreecommitdiffstats
path: root/kernel/time/clockevents.c
diff options
context:
space:
mode:
Diffstat (limited to 'kernel/time/clockevents.c')
-rw-r--r--kernel/time/clockevents.c125
1 files changed, 111 insertions, 14 deletions
diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c
index e4c699dfa4e..713ef94ecee 100644
--- a/kernel/time/clockevents.c
+++ b/kernel/time/clockevents.c
@@ -94,42 +94,139 @@ void clockevents_shutdown(struct clock_event_device *dev)
dev->next_event.tv64 = KTIME_MAX;
}
+#ifdef CONFIG_GENERIC_CLOCKEVENTS_MIN_ADJUST
+
+/* Limit min_delta to a jiffie */
+#define MIN_DELTA_LIMIT (NSEC_PER_SEC / HZ)
+
+/**
+ * clockevents_increase_min_delta - raise minimum delta of a clock event device
+ * @dev: device to increase the minimum delta
+ *
+ * Returns 0 on success, -ETIME when the minimum delta reached the limit.
+ */
+static int clockevents_increase_min_delta(struct clock_event_device *dev)
+{
+ /* Nothing to do if we already reached the limit */
+ if (dev->min_delta_ns >= MIN_DELTA_LIMIT) {
+ printk(KERN_WARNING "CE: Reprogramming failure. Giving up\n");
+ dev->next_event.tv64 = KTIME_MAX;
+ return -ETIME;
+ }
+
+ if (dev->min_delta_ns < 5000)
+ dev->min_delta_ns = 5000;
+ else
+ dev->min_delta_ns += dev->min_delta_ns >> 1;
+
+ if (dev->min_delta_ns > MIN_DELTA_LIMIT)
+ dev->min_delta_ns = MIN_DELTA_LIMIT;
+
+ printk(KERN_WARNING "CE: %s increased min_delta_ns to %llu nsec\n",
+ dev->name ? dev->name : "?",
+ (unsigned long long) dev->min_delta_ns);
+ return 0;
+}
+
+/**
+ * clockevents_program_min_delta - Set clock event device to the minimum delay.
+ * @dev: device to program
+ *
+ * Returns 0 on success, -ETIME when the retry loop failed.
+ */
+static int clockevents_program_min_delta(struct clock_event_device *dev)
+{
+ unsigned long long clc;
+ int64_t delta;
+ int i;
+
+ for (i = 0;;) {
+ delta = dev->min_delta_ns;
+ dev->next_event = ktime_add_ns(ktime_get(), delta);
+
+ if (dev->mode == CLOCK_EVT_MODE_SHUTDOWN)
+ return 0;
+
+ dev->retries++;
+ clc = ((unsigned long long) delta * dev->mult) >> dev->shift;
+ if (dev->set_next_event((unsigned long) clc, dev) == 0)
+ return 0;
+
+ if (++i > 2) {
+ /*
+ * We tried 3 times to program the device with the
+ * given min_delta_ns. Try to increase the minimum
+ * delta, if that fails as well get out of here.
+ */
+ if (clockevents_increase_min_delta(dev))
+ return -ETIME;
+ i = 0;
+ }
+ }
+}
+
+#else /* CONFIG_GENERIC_CLOCKEVENTS_MIN_ADJUST */
+
+/**
+ * clockevents_program_min_delta - Set clock event device to the minimum delay.
+ * @dev: device to program
+ *
+ * Returns 0 on success, -ETIME when the retry loop failed.
+ */
+static int clockevents_program_min_delta(struct clock_event_device *dev)
+{
+ unsigned long long clc;
+ int64_t delta;
+
+ delta = dev->min_delta_ns;
+ dev->next_event = ktime_add_ns(ktime_get(), delta);
+
+ if (dev->mode == CLOCK_EVT_MODE_SHUTDOWN)
+ return 0;
+
+ dev->retries++;
+ clc = ((unsigned long long) delta * dev->mult) >> dev->shift;
+ return dev->set_next_event((unsigned long) clc, dev);
+}
+
+#endif /* CONFIG_GENERIC_CLOCKEVENTS_MIN_ADJUST */
+
/**
* clockevents_program_event - Reprogram the clock event device.
+ * @dev: device to program
* @expires: absolute expiry time (monotonic clock)
+ * @force: program minimum delay if expires can not be set
*
* Returns 0 on success, -ETIME when the event is in the past.
*/
int clockevents_program_event(struct clock_event_device *dev, ktime_t expires,
- ktime_t now)
+ bool force)
{
unsigned long long clc;
int64_t delta;
+ int rc;
if (unlikely(expires.tv64 < 0)) {
WARN_ON_ONCE(1);
return -ETIME;
}
- delta = ktime_to_ns(ktime_sub(expires, now));
-
- if (delta <= 0)
- return -ETIME;
-
dev->next_event = expires;
if (dev->mode == CLOCK_EVT_MODE_SHUTDOWN)
return 0;
- if (delta > dev->max_delta_ns)
- delta = dev->max_delta_ns;
- if (delta < dev->min_delta_ns)
- delta = dev->min_delta_ns;
+ delta = ktime_to_ns(ktime_sub(expires, ktime_get()));
+ if (delta <= 0)
+ return force ? clockevents_program_min_delta(dev) : -ETIME;
- clc = delta * dev->mult;
- clc >>= dev->shift;
+ delta = min(delta, (int64_t) dev->max_delta_ns);
+ delta = max(delta, (int64_t) dev->min_delta_ns);
- return dev->set_next_event((unsigned long) clc, dev);
+ clc = ((unsigned long long) delta * dev->mult) >> dev->shift;
+ rc = dev->set_next_event((unsigned long) clc, dev);
+
+ return (rc && force) ? clockevents_program_min_delta(dev) : rc;
}
/**
@@ -258,7 +355,7 @@ int clockevents_update_freq(struct clock_event_device *dev, u32 freq)
if (dev->mode != CLOCK_EVT_MODE_ONESHOT)
return 0;
- return clockevents_program_event(dev, dev->next_event, ktime_get());
+ return clockevents_program_event(dev, dev->next_event, false);
}
/*