sim: Add support for dynamic frequency scaling

This patch provides support for DFS by having ClockedObjects register
themselves with their clock domain at construction time in a member list.
Using this list, a clock domain can update each member's tick to the
curTick() before modifying the clock period.

Committed by: Nilay Vaish <nilay@cs.wisc.edu>

1 files changed, 13 insertions, 0 deletions

diff --git a/src/sim/clock_domain.cc b/src/sim/clock_domain.cc
index 8b563d598..ff96f2808 100644
--- a/src/sim/clock_domain.cc
+++ b/src/sim/clock_domain.cc
@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2013 ARM Limited
+ * Copyright (c) 2013 Cornell University
  * All rights reserved
  *
  * The license below extends only to copyright in the software and shall
@@ -37,6 +38,7 @@
  * Authors: Vasileios Spiliopoulos
  *          Akash Bagdia
  *          Andreas Hansson
+ *          Christopher Torng
  */
 
 #include "debug/ClockDomain.hh"
@@ -45,6 +47,7 @@
 #include "params/SrcClockDomain.hh"
 #include "sim/clock_domain.hh"
 #include "sim/voltage_domain.hh"
+#include "sim/clocked_object.hh"
 
 double
 ClockDomain::voltage() const
@@ -65,6 +68,11 @@ SrcClockDomain::clockPeriod(Tick clock_period)
         fatal("%s has a clock period of zero\n", name());
     }
 
+    // Align all members to the current tick
+    for (auto m = members.begin(); m != members.end(); ++m) {
+        (*m)->updateClockPeriod();
+    }
+
     _clockPeriod = clock_period;
 
     DPRINTF(ClockDomain,
@@ -105,6 +113,11 @@ DerivedClockDomain::DerivedClockDomain(const Params *p) :
 void
 DerivedClockDomain::updateClockPeriod()
 {
+    // Align all members to the current tick
+    for (auto m = members.begin(); m != members.end(); ++m) {
+        (*m)->updateClockPeriod();
+    }
+
     // recalculate the clock period, relying on the fact that changes
     // propagate downwards in the tree
     _clockPeriod = parent.clockPeriod() * clockDivider;