MFC 264019, 264041, 264048, 264049, 264050, 264051

  Add support for event timers whose clock frequency can change while running.

  Apparently all ARM configs build kern_et.c, but only a few of them also
  build kern_clocksource.c, un-break the build by not referencing functions in
  kern_clocksource if NO_EVENTTIMERS is defined.

  Add variable-frequency support to the arm mpcore eventtimer driver.

  mpcore_timer: Disable the timer and clear any pending bit, then setup the
  new counter register values, then restart the timer.  Also re-nest the parens
  properly for casting the result of converting time and frequency to a count.

1 files changed, 19 insertions, 0 deletions

diff --git a/sys/kern/kern_clocksource.c b/sys/kern/kern_clocksource.c
index 0edb238..c76750f 100644
--- a/sys/kern/kern_clocksource.c
+++ b/sys/kern/kern_clocksource.c
@@ -800,6 +800,25 @@ cpu_activeclock(void)
 	spinlock_exit();
 }
 
+/*
+ * Change the frequency of the given timer.  This changes et->et_frequency and
+ * if et is the active timer it reconfigures the timer on all CPUs.  This is
+ * intended to be a private interface for the use of et_change_frequency() only.
+ */
+void
+cpu_et_frequency(struct eventtimer *et, uint64_t newfreq)
+{
+
+	ET_LOCK();
+	if (et == timer) {
+		configtimer(0);
+		et->et_frequency = newfreq;
+		configtimer(1);
+	} else
+		et->et_frequency = newfreq;
+	ET_UNLOCK();
+}
+
 #ifdef KDTRACE_HOOKS
 void
 clocksource_cyc_set(const struct bintime *bt)