Reenable RTC interrupts after wakeup. Some laptops have a problem

with system statistics monitoring tools (such as systat, vmstat...)
because of stopping RTC interrupts generation.
Restore all the timers (RTC and i8254) atomically.

Reviewed by:	bde
MFC after:	1 week

1 files changed, 22 insertions, 1 deletions

diff --git a/sys/isa/atrtc.c b/sys/isa/atrtc.c
index e0a638e..1893b19 100644
--- a/sys/isa/atrtc.c
+++ b/sys/isa/atrtc.c
@@ -705,7 +705,7 @@ set_timer_freq(u_int freq, int intr_freq)
  * when it happnes, it messes up the hardclock interval and system clock,
  * which leads to the infamous "calcru: negative time" problem.
  */
-void
+static void
 i8254_restore(void)
 {
 
@@ -716,6 +716,27 @@ i8254_restore(void)
 	mtx_unlock_spin(&clock_lock);
 }
 
+static void
+rtc_restore(void)
+{
+
+	/* Reenable RTC updates and interrupts. */
+	/* XXX locking is needed for RTC access? */
+	writertc(RTC_STATUSB, RTCSB_HALT | RTCSB_24HR);
+	writertc(RTC_STATUSB, rtc_statusb);
+}
+
+/*
+ * Restore all the timers atomically.
+ */
+void
+timer_restore(void)
+{
+
+	i8254_restore();		/* restore timer_freq and hz */
+	rtc_restore();			/* reenable RTC interrupts */
+}
+
 /*
  * Initialize 8254 timer 0 early so that it can be used in DELAY().
  * XXX initialization of other timers is unintentionally left blank.