4 files changed, 187 insertions, 194 deletions

diff --git a/src/mem/cache/base.cc b/src/mem/cache/base.cc
index 27ff6961b..c7c213cc6 100644
--- a/src/mem/cache/base.cc
+++ b/src/mem/cache/base.cc
@@ -1,4 +1,16 @@
 /*
+ * Copyright (c) 2012 ARM Limited
+ * All rights reserved.
+ *
+ * The license below extends only to copyright in the software and shall
+ * not be construed as granting a license to any other intellectual
+ * property including but not limited to intellectual property relating
+ * to a hardware implementation of the functionality of the software
+ * licensed hereunder.  You may use the software subject to the license
+ * terms below provided that you ensure that this notice is replicated
+ * unmodified and in its entirety in all distributions of the software,
+ * modified or unmodified, in source code or in binary form.
+ *
  * Copyright (c) 2003-2005 The Regents of The University of Michigan
  * All rights reserved.
  *
@@ -42,13 +54,20 @@
 
 using namespace std;
 
-BaseCache::CachePort::CachePort(const std::string &_name, BaseCache *_cache,
-                                const std::string &_label)
-    : SimpleTimingPort(_name, _cache), cache(_cache),
-      label(_label), blocked(false), mustSendRetry(false)
+BaseCache::CacheMasterPort::CacheMasterPort(const std::string &_name,
+                                            BaseCache *_cache,
+                                            const std::string &_label)
+    : SimpleTimingPort(_name, _cache, _label)
 {
 }
 
+BaseCache::CacheSlavePort::CacheSlavePort(const std::string &_name,
+                                          BaseCache *_cache,
+                                          const std::string &_label)
+    : SimpleTimingPort(_name, _cache, _label), blocked(false),
+      mustSendRetry(false), sendRetryEvent(this)
+{
+}
 
 BaseCache::BaseCache(const Params *p)
     : MemObject(p),
@@ -69,56 +88,25 @@ BaseCache::BaseCache(const Params *p)
 {
 }
 
-
-bool
-BaseCache::CachePort::checkFunctional(PacketPtr pkt)
-{
-    pkt->pushLabel(label);
-    bool done = SimpleTimingPort::checkFunctional(pkt);
-    pkt->popLabel();
-    return done;
-}
-
-
-unsigned
-BaseCache::CachePort::deviceBlockSize() const
-{
-    return cache->getBlockSize();
-}
-
-
-bool
-BaseCache::CachePort::recvRetryCommon()
-{
-    assert(waitingOnRetry);
-    waitingOnRetry = false;
-    return false;
-}
-
-
 void
-BaseCache::CachePort::setBlocked()
+BaseCache::CacheSlavePort::setBlocked()
 {
     assert(!blocked);
-    DPRINTF(Cache, "Cache Blocking\n");
+    DPRINTF(CachePort, "Cache port %s blocking new requests\n", name());
     blocked = true;
-    //Clear the retry flag
-    mustSendRetry = false;
 }
 
 void
-BaseCache::CachePort::clearBlocked()
+BaseCache::CacheSlavePort::clearBlocked()
 {
     assert(blocked);
-    DPRINTF(Cache, "Cache Unblocking\n");
+    DPRINTF(CachePort, "Cache port %s accepting new requests\n", name());
     blocked = false;
-    if (mustSendRetry)
-    {
-        DPRINTF(Cache, "Cache Sending Retry\n");
+    if (mustSendRetry) {
+        DPRINTF(CachePort, "Cache port %s sending retry\n", name());
         mustSendRetry = false;
-        SendRetryEvent *ev = new SendRetryEvent(this, true);
         // @TODO: need to find a better time (next bus cycle?)
-        cache->schedule(ev, curTick() + 1);
+        owner->schedule(sendRetryEvent, curTick() + 1);
     }
 }
 
@@ -126,8 +114,8 @@ BaseCache::CachePort::clearBlocked()
 void
 BaseCache::init()
 {
-    if (!cpuSidePort || !memSidePort)
-        panic("Cache not hooked up on both sides\n");
+    if (!cpuSidePort->isConnected() || !memSidePort->isConnected())
+        panic("Cache %s not hooked up on both sides\n", name());
     cpuSidePort->sendRangeChange();
 }
 
diff --git a/src/mem/cache/base.hh b/src/mem/cache/base.hh
index cff8813cd..e522bc0c9 100644
--- a/src/mem/cache/base.hh
+++ b/src/mem/cache/base.hh
@@ -1,4 +1,16 @@
 /*
+ * Copyright (c) 2012 ARM Limited
+ * All rights reserved.
+ *
+ * The license below extends only to copyright in the software and shall
+ * not be construed as granting a license to any other intellectual
+ * property including but not limited to intellectual property relating
+ * to a hardware implementation of the functionality of the software
+ * licensed hereunder.  You may use the software subject to the license
+ * terms below provided that you ensure that this notice is replicated
+ * unmodified and in its entirety in all distributions of the software,
+ * modified or unmodified, in source code or in binary form.
+ *
  * Copyright (c) 2003-2005 The Regents of The University of Michigan
  * All rights reserved.
  *
@@ -97,50 +109,88 @@ class BaseCache : public MemObject
 
   protected:
 
-    class CachePort : public SimpleTimingPort
+    /**
+     * A cache master port is used for the memory-side port of the
+     * cache, and in addition to the basic timing port that only sends
+     * response packets through a transmit list, it also offers the
+     * ability to schedule and send request packets (requests &
+     * writebacks). The send event is scheduled through requestBus,
+     * and the sendDeferredPacket of the timing port is modified to
+     * consider both the transmit list and the requests from the MSHR.
+     */
+    class CacheMasterPort : public SimpleTimingPort
     {
+
       public:
-        BaseCache *cache;
 
-      protected:
-        CachePort(const std::string &_name, BaseCache *_cache,
-                  const std::string &_label);
+        /**
+         * Schedule a send of a request packet (from the MSHR). Note
+         * that we could already have a retry or a transmit list of
+         * responses outstanding.
+         */
+        void requestBus(RequestCause cause, Tick time)
+        {
+            DPRINTF(CachePort, "Asserting bus request for cause %d\n", cause);
+            schedSendEvent(time);
+        }
 
-        virtual unsigned deviceBlockSize() const;
+        void respond(PacketPtr pkt, Tick time) {
+            schedSendTiming(pkt, time);
+        }
 
-        bool recvRetryCommon();
+      protected:
 
-        typedef EventWrapper<Port, &Port::sendRetry>
-            SendRetryEvent;
+        CacheMasterPort(const std::string &_name, BaseCache *_cache,
+                        const std::string &_label);
 
-        const std::string label;
+        /**
+         * Memory-side port always snoops.
+         *
+         * return always true
+         */
+        virtual bool isSnooping() { return true; }
+    };
+
+    /**
+     * A cache slave port is used for the CPU-side port of the cache,
+     * and it is basically a simple timing port that uses a transmit
+     * list for responses to the CPU (or connected master). In
+     * addition, it has the functionality to block the port for
+     * incoming requests. If blocked, the port will issue a retry once
+     * unblocked.
+     */
+    class CacheSlavePort : public SimpleTimingPort
+    {
 
       public:
+
+        /** Do not accept any new requests. */
         void setBlocked();
 
+        /** Return to normal operation and accept new requests. */
         void clearBlocked();
 
-        bool checkFunctional(PacketPtr pkt);
+        void respond(PacketPtr pkt, Tick time) {
+            schedSendTiming(pkt, time);
+        }
+
+      protected:
+
+        CacheSlavePort(const std::string &_name, BaseCache *_cache,
+                       const std::string &_label);
 
         bool blocked;
 
         bool mustSendRetry;
 
-        void requestBus(RequestCause cause, Tick time)
-        {
-            DPRINTF(CachePort, "Asserting bus request for cause %d\n", cause);
-            if (!waitingOnRetry) {
-                schedSendEvent(time);
-            }
-        }
+      private:
+
+        EventWrapper<Port, &Port::sendRetry> sendRetryEvent;
 
-        void respond(PacketPtr pkt, Tick time) {
-            schedSendTiming(pkt, time);
-        }
     };
 
-    CachePort *cpuSidePort;
-    CachePort *memSidePort;
+    CacheSlavePort *cpuSidePort;
+    CacheMasterPort *memSidePort;
 
   protected:
 
diff --git a/src/mem/cache/cache.hh b/src/mem/cache/cache.hh
index b2569648e..288395584 100644
--- a/src/mem/cache/cache.hh
+++ b/src/mem/cache/cache.hh
@@ -41,6 +41,7 @@
  *          Dave Greene
  *          Steve Reinhardt
  *          Ron Dreslinski
+ *          Andreas Hansson
  */
 
 /**
@@ -76,59 +77,68 @@ class Cache : public BaseCache
 
   protected:
 
-    class CpuSidePort : public CachePort
+    /**
+     * The CPU-side port extends the base cache slave port with access
+     * functions for functional, atomic and timing requests.
+     */
+    class CpuSidePort : public CacheSlavePort
     {
-      public:
-        CpuSidePort(const std::string &_name,
-                    Cache<TagStore> *_cache,
-                    const std::string &_label);
+      private:
 
-        // BaseCache::CachePort just has a BaseCache *; this function
-        // lets us get back the type info we lost when we stored the
-        // cache pointer there.
-        Cache<TagStore> *myCache() {
-            return static_cast<Cache<TagStore> *>(cache);
-        }
+        // a pointer to our specific cache implementation
+        Cache<TagStore> *cache;
 
-        virtual AddrRangeList getAddrRanges();
+      protected:
 
         virtual bool recvTiming(PacketPtr pkt);
 
         virtual Tick recvAtomic(PacketPtr pkt);
 
         virtual void recvFunctional(PacketPtr pkt);
-    };
 
-    class MemSidePort : public CachePort
-    {
+        virtual unsigned deviceBlockSize() const
+        { return cache->getBlockSize(); }
+
+        virtual AddrRangeList getAddrRanges();
+
       public:
-        MemSidePort(const std::string &_name,
-                    Cache<TagStore> *_cache,
+
+        CpuSidePort(const std::string &_name, Cache<TagStore> *_cache,
                     const std::string &_label);
 
-        // BaseCache::CachePort just has a BaseCache *; this function
-        // lets us get back the type info we lost when we stored the
-        // cache pointer there.
-        Cache<TagStore> *myCache() {
-            return static_cast<Cache<TagStore> *>(cache);
-        }
+    };
 
-        void sendPacket();
+    /**
+     * The memory-side port extends the base cache master port with
+     * access functions for functional, atomic and timing snoops.
+     */
+    class MemSidePort : public CacheMasterPort
+    {
+      private:
 
-        void processSendEvent();
+        // a pointer to our specific cache implementation
+        Cache<TagStore> *cache;
 
-        virtual bool isSnooping();
+      protected:
 
         virtual bool recvTiming(PacketPtr pkt);
 
-        virtual void recvRetry();
-
         virtual Tick recvAtomic(PacketPtr pkt);
 
         virtual void recvFunctional(PacketPtr pkt);
 
-        typedef EventWrapper<MemSidePort, &MemSidePort::processSendEvent>
-                SendEvent;
+        virtual unsigned deviceBlockSize() const
+        { return cache->getBlockSize(); }
+
+      public:
+
+        MemSidePort(const std::string &_name, Cache<TagStore> *_cache,
+                    const std::string &_label);
+
+        /**
+         * Overload sendDeferredPacket of SimpleTimingPort.
+         */
+        virtual void sendDeferredPacket();
     };
 
     /** Tag and data Storage */
diff --git a/src/mem/cache/cache_impl.hh b/src/mem/cache/cache_impl.hh
index 87b688617..40359d31e 100644
--- a/src/mem/cache/cache_impl.hh
+++ b/src/mem/cache/cache_impl.hh
@@ -95,7 +95,7 @@ template<class TagStore>
 Port *
 Cache<TagStore>::getPort(const std::string &if_name, int idx)
 {
-    if (if_name == "" || if_name == "cpu_side") {
+    if (if_name == "cpu_side") {
         return cpuSidePort;
     } else if (if_name == "mem_side") {
         return memSidePort;
@@ -1553,17 +1553,13 @@ Cache<TagStore>::nextMSHRReadyTime()
 
 template<class TagStore>
 AddrRangeList
-Cache<TagStore>::CpuSidePort::
-getAddrRanges()
+Cache<TagStore>::CpuSidePort::getAddrRanges()
 {
-    // CPU side port doesn't snoop; it's a target only.  It can
-    // potentially respond to any address.
     AddrRangeList ranges;
-    ranges.push_back(myCache()->getAddrRange());
+    ranges.push_back(cache->getAddrRange());
     return ranges;
 }
 
-
 template<class TagStore>
 bool
 Cache<TagStore>::CpuSidePort::recvTiming(PacketPtr pkt)
@@ -1575,32 +1571,33 @@ Cache<TagStore>::CpuSidePort::recvTiming(PacketPtr pkt)
         return false;
     }
 
-    myCache()->timingAccess(pkt);
+    cache->timingAccess(pkt);
     return true;
 }
 
-
 template<class TagStore>
 Tick
 Cache<TagStore>::CpuSidePort::recvAtomic(PacketPtr pkt)
 {
-    return myCache()->atomicAccess(pkt);
+    assert(pkt->isRequest());
+    // atomic request
+    return cache->atomicAccess(pkt);
 }
 
-
 template<class TagStore>
 void
 Cache<TagStore>::CpuSidePort::recvFunctional(PacketPtr pkt)
 {
-    myCache()->functionalAccess(pkt, true);
+    assert(pkt->isRequest());
+    // functional request
+    cache->functionalAccess(pkt, true);
 }
 
-
 template<class TagStore>
 Cache<TagStore>::
 CpuSidePort::CpuSidePort(const std::string &_name, Cache<TagStore> *_cache,
                          const std::string &_label)
-    : BaseCache::CachePort(_name, _cache, _label)
+    : BaseCache::CacheSlavePort(_name, _cache, _label), cache(_cache)
 {
 }
 
@@ -1612,17 +1609,6 @@ CpuSidePort::CpuSidePort(const std::string &_name, Cache<TagStore> *_cache,
 
 template<class TagStore>
 bool
-Cache<TagStore>::MemSidePort::isSnooping()
-{
-    // Memory-side port always snoops, but never passes requests
-    // through to targets on the cpu side (so we don't add anything to
-    // the address range list).
-    return true;
-}
-
-
-template<class TagStore>
-bool
 Cache<TagStore>::MemSidePort::recvTiming(PacketPtr pkt)
 {
     // this needs to be fixed so that the cache updates the mshr and sends the
@@ -1631,60 +1617,45 @@ Cache<TagStore>::MemSidePort::recvTiming(PacketPtr pkt)
     if (pkt->wasNacked())
         panic("Need to implement cache resending nacked packets!\n");
 
-    if (pkt->isRequest() && blocked) {
-        DPRINTF(Cache,"Scheduling a retry while blocked\n");
-        mustSendRetry = true;
-        return false;
-    }
-
     if (pkt->isResponse()) {
-        myCache()->handleResponse(pkt);
+        cache->handleResponse(pkt);
     } else {
-        myCache()->snoopTiming(pkt);
+        cache->snoopTiming(pkt);
     }
     return true;
 }
 
-
 template<class TagStore>
 Tick
 Cache<TagStore>::MemSidePort::recvAtomic(PacketPtr pkt)
 {
-    // in atomic mode, responses go back to the sender via the
-    // function return from sendAtomic(), not via a separate
-    // sendAtomic() from the responder.  Thus we should never see a
-    // response packet in recvAtomic() (anywhere, not just here).
-    assert(!pkt->isResponse());
-    return myCache()->snoopAtomic(pkt);
+    assert(pkt->isRequest());
+    // atomic snoop
+    return cache->snoopAtomic(pkt);
 }
 
-
 template<class TagStore>
 void
 Cache<TagStore>::MemSidePort::recvFunctional(PacketPtr pkt)
 {
-    myCache()->functionalAccess(pkt, false);
+    assert(pkt->isRequest());
+    // functional snoop (note that in contrast to atomic we don't have
+    // a specific functionalSnoop method, as they have the same
+    // behaviour regardless)
+    cache->functionalAccess(pkt, false);
 }
 
-
-
 template<class TagStore>
 void
-Cache<TagStore>::MemSidePort::sendPacket()
+Cache<TagStore>::MemSidePort::sendDeferredPacket()
 {
-    // if we have responses that are ready, they take precedence
+    // if we have a response packet waiting we have to start with that
     if (deferredPacketReady()) {
-        bool success = sendTiming(transmitList.front().pkt);
-
-        if (success) {
-            //send successful, remove packet
-            transmitList.pop_front();
-        }
-
-        waitingOnRetry = !success;
+        // use the normal approach from the timing port
+        trySendTiming();
     } else {
-        // check for non-response packets (requests & writebacks)
-        PacketPtr pkt = myCache()->getTimingPacket();
+        // check for request packets (requests & writebacks)
+        PacketPtr pkt = cache->getTimingPacket();
         if (pkt == NULL) {
             // can happen if e.g. we attempt a writeback and fail, but
             // before the retry, the writeback is eliminated because
@@ -1693,65 +1664,39 @@ Cache<TagStore>::MemSidePort::sendPacket()
         } else {
             MSHR *mshr = dynamic_cast<MSHR*>(pkt->senderState);
 
-            bool success = sendTiming(pkt);
+            waitingOnRetry = !sendTiming(pkt);
 
-            waitingOnRetry = !success;
             if (waitingOnRetry) {
                 DPRINTF(CachePort, "now waiting on a retry\n");
                 if (!mshr->isForwardNoResponse()) {
+                    // we are awaiting a retry, but we
+                    // delete the packet and will be creating a new packet
+                    // when we get the opportunity
                     delete pkt;
                 }
+                // note that we have now masked any requestBus and
+                // schedSendEvent (we will wait for a retry before
+                // doing anything), and this is so even if we do not
+                // care about this packet and might override it before
+                // it gets retried
             } else {
-                myCache()->markInService(mshr, pkt);
+                cache->markInService(mshr, pkt);
             }
         }
     }
 
-
-    // tried to send packet... if it was successful (no retry), see if
-    // we need to rerequest bus or not
+    // if we succeeded and are not waiting for a retry, schedule the
+    // next send, not only looking at the response transmit list, but
+    // also considering when the next MSHR is ready
     if (!waitingOnRetry) {
-        Tick nextReady = std::min(deferredPacketReadyTime(),
-                                  myCache()->nextMSHRReadyTime());
-        // @TODO: need to facotr in prefetch requests here somehow
-        if (nextReady != MaxTick) {
-            DPRINTF(CachePort, "more packets to send @ %d\n", nextReady);
-            cache->schedule(sendEvent, std::max(nextReady, curTick() + 1));
-        } else {
-            // no more to send right now: if we're draining, we may be done
-            if (drainEvent && !sendEvent->scheduled()) {
-                drainEvent->process();
-                drainEvent = NULL;
-            }
-        }
+        scheduleSend(cache->nextMSHRReadyTime());
     }
 }
 
 template<class TagStore>
-void
-Cache<TagStore>::MemSidePort::recvRetry()
-{
-    assert(waitingOnRetry);
-    sendPacket();
-}
-
-
-template<class TagStore>
-void
-Cache<TagStore>::MemSidePort::processSendEvent()
-{
-    assert(!waitingOnRetry);
-    sendPacket();
-}
-
-
-template<class TagStore>
 Cache<TagStore>::
 MemSidePort::MemSidePort(const std::string &_name, Cache<TagStore> *_cache,
                          const std::string &_label)
-    : BaseCache::CachePort(_name, _cache, _label)
+    : BaseCache::CacheMasterPort(_name, _cache, _label), cache(_cache)
 {
-    // override default send event from SimpleTimingPort
-    delete sendEvent;
-    sendEvent = new SendEvent(this);
 }