devices: Fixed periodic interrupts to work with draining

Added drain functions to the RTC and 8254 timer so that periodic interrupts
stop when the system is draining.  This patch is needed to checkpoint in
timing mode.  Otherwise under certain situations, the event queue will never
be completely empty.

1 files changed, 21 insertions, 4 deletions

diff --git a/src/dev/mc146818.cc b/src/dev/mc146818.cc
index 16ed58e46..fd70b503b 100644
--- a/src/dev/mc146818.cc
+++ b/src/dev/mc146818.cc
@@ -40,6 +40,7 @@
 #include "base/trace.hh"
 #include "dev/mc146818.hh"
 #include "dev/rtcreg.h"
+#include "sim/sim_object.hh"
 
 using namespace std;
 
@@ -105,8 +106,12 @@ MC146818::MC146818(EventManager *em, const string &n, const struct tm time,
 
 MC146818::~MC146818()
 {
-    deschedule(tickEvent);
-    deschedule(event);
+    if (tickEvent.scheduled()) {
+        deschedule(tickEvent);
+    }
+    if (event.scheduled()) {
+        deschedule(event);
+    }
 }
 
 void
@@ -203,6 +208,20 @@ MC146818::tickClock()
     setTime(*gmtime(&calTime));
 }
 
+unsigned int 
+MC146818::drain(Event *de)
+{
+    if (event.scheduled()) {
+        rtcTimerInterruptTickOffset = event.when() - curTick;
+        rtcClockTickOffset = event.when() - curTick;
+        deschedule(event);
+    }
+    if (tickEvent.scheduled()) {
+        deschedule(tickEvent);
+    }
+    return 0;
+}
+
 void
 MC146818::serialize(const string &base, ostream &os)
 {
@@ -214,9 +233,7 @@ MC146818::serialize(const string &base, ostream &os)
     // save the timer tick and rtc clock tick values to correctly reschedule 
     // them during unserialize
     //
-    Tick rtcTimerInterruptTickOffset = event.when() - curTick;
     SERIALIZE_SCALAR(rtcTimerInterruptTickOffset);
-    Tick rtcClockTickOffset = event.when() - curTick;
     SERIALIZE_SCALAR(rtcClockTickOffset);
 }