[XTENSA] Fix timer instabilities.
The timer code could have missed a tick.
Signed-off-by: Chris Zankel <chris@zankel.net>
diff --git a/arch/xtensa/kernel/time.c b/arch/xtensa/kernel/time.c
index 22949be..60d29fe 100644
--- a/arch/xtensa/kernel/time.c
+++ b/arch/xtensa/kernel/time.c
@@ -32,12 +32,20 @@
#ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT
unsigned long ccount_per_jiffy; /* per 1/HZ */
-unsigned long ccount_nsec; /* nsec per ccount increment */
+unsigned long nsec_per_ccount; /* nsec per ccount increment */
#endif
-unsigned int last_ccount_stamp;
static long last_rtc_update = 0;
+/*
+ * Scheduler clock - returns current tim in nanosec units.
+ */
+
+unsigned long long sched_clock(void)
+{
+ return (unsigned long long)jiffies * (1000000000 / HZ);
+}
+
static irqreturn_t timer_interrupt(int irq, void *dev_id);
static struct irqaction timer_irqaction = {
.handler = timer_interrupt,
@@ -69,7 +77,6 @@
xtime.tv_nsec = 0;
last_rtc_update = xtime.tv_sec = sec_n;
- last_ccount_stamp = get_ccount();
set_normalized_timespec(&wall_to_monotonic,
-xtime.tv_sec, -xtime.tv_nsec);
@@ -85,7 +92,7 @@
{
time_t wtm_sec, sec = tv->tv_sec;
long wtm_nsec, nsec = tv->tv_nsec;
- unsigned long ccount;
+ unsigned long delta;
if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
return -EINVAL;
@@ -97,8 +104,10 @@
* wall time. Discover what correction gettimeofday() would have
* made, and then undo it!
*/
- ccount = get_ccount();
- nsec -= (ccount - last_ccount_stamp) * CCOUNT_NSEC;
+
+ delta = CCOUNT_PER_JIFFY;
+ delta += get_ccount() - get_linux_timer();
+ nsec -= delta * NSEC_PER_CCOUNT;
wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
@@ -117,17 +126,21 @@
void do_gettimeofday(struct timeval *tv)
{
unsigned long flags;
- unsigned long sec, usec, delta, seq;
+ unsigned long volatile sec, usec, delta, seq;
do {
seq = read_seqbegin_irqsave(&xtime_lock, flags);
- delta = get_ccount() - last_ccount_stamp;
sec = xtime.tv_sec;
usec = (xtime.tv_nsec / NSEC_PER_USEC);
+
+ delta = get_linux_timer() - get_ccount();
+
} while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
- usec += (delta * CCOUNT_NSEC) / NSEC_PER_USEC;
+ usec += (((unsigned long) CCOUNT_PER_JIFFY - delta)
+ * (unsigned long) NSEC_PER_CCOUNT) / NSEC_PER_USEC;
+
for (; usec >= 1000000; sec++, usec -= 1000000)
;
@@ -158,9 +171,12 @@
write_seqlock(&xtime_lock);
- last_ccount_stamp = next;
+ do_timer(1); /* Linux handler in kernel/timer.c */
+
+ /* Note that writing CCOMPARE clears the interrupt. */
+
next += CCOUNT_PER_JIFFY;
- do_timer (1); /* Linux handler in kernel/timer.c */
+ set_linux_timer(next);
if (ntp_synced() &&
xtime.tv_sec - last_rtc_update >= 659 &&
@@ -175,19 +191,15 @@
write_sequnlock(&xtime_lock);
}
- /* NOTE: writing CCOMPAREn clears the interrupt. */
+ /* Allow platform to do something useful (Wdog). */
- set_linux_timer (next);
+ platform_heartbeat();
/* Make sure we didn't miss any tick... */
if ((signed long)(get_ccount() - next) > 0)
goto again;
- /* Allow platform to do something useful (Wdog). */
-
- platform_heartbeat();
-
return IRQ_HANDLED;
}