src/mem/bridge.hh

   1 /*
   2  * Copyright (c) 2006 The Regents of The University of Michigan
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions are
   7  * met: redistributions of source code must retain the above copyright
   8  * notice, this list of conditions and the following disclaimer;
   9  * redistributions in binary form must reproduce the above copyright
  10  * notice, this list of conditions and the following disclaimer in the
  11  * documentation and/or other materials provided with the distribution;
  12  * neither the name of the copyright holders nor the names of its
  13  * contributors may be used to endorse or promote products derived from
  14  * this software without specific prior written permission.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  17  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  18  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  19  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  20  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  21  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  22  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  26  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27  *
  28  * Authors: Ali Saidi
  29  *          Steve Reinhardt
  30  */
  31
  32 /**
  33  * @file
  34  * Declaration of a simple bus bridge object with no buffering
  35  */
  36
  37 #ifndef __MEM_BRIDGE_HH__
  38 #define __MEM_BRIDGE_HH__
  39
  40 #include <string>
  41 #include <list>
  42 #include <inttypes.h>
  43 #include <queue>
  44
  45 #include "mem/mem_object.hh"
  46 #include "mem/packet.hh"
  47 #include "mem/port.hh"
  48 #include "sim/eventq.hh"
  49
  50 class Bridge : public MemObject
  51 {
  52   protected:
  53     /** Declaration of the buses port type, one will be instantiated for each
  54         of the interfaces connecting to the bus. */
  55     class BridgePort : public Port
  56     {
  57         /** A pointer to the bridge to which this port belongs. */
  58         Bridge *bridge;
  59
  60         /**
  61          * Pointer to the port on the other side of the bridge
  62          * (connected to the other bus).
  63          */
  64         BridgePort *otherPort;
  65
  66         /** Minimum delay though this bridge. */
  67         Tick delay;
  68
  69         class PacketBuffer : public Packet::SenderState {
  70
  71           public:
  72             Tick ready;
  73             PacketPtr pkt;
  74             Packet::SenderState *origSenderState;
  75             short origSrc;
  76             bool expectResponse;
  77
  78             PacketBuffer(PacketPtr _pkt, Tick t)
  79                 : ready(t), pkt(_pkt),
  80                   origSenderState(_pkt->senderState), origSrc(_pkt->getSrc()),
  81                   expectResponse(_pkt->needsResponse())
  82             {
  83                 if (!pkt->isResponse())
  84                     pkt->senderState = this;
  85             }
  86
  87             void fixResponse(PacketPtr pkt)
  88             {
  89                 assert(pkt->senderState == this);
  90                 pkt->setDest(origSrc);
  91                 pkt->senderState = origSenderState;
  92             }
  93         };
  94
  95         /**
  96          * Outbound packet queue.  Packets are held in this queue for a
  97          * specified delay to model the processing delay of the
  98          * bridge.
  99          */
 100         std::list<PacketBuffer*> sendQueue;
 101
 102         int outstandingResponses;
 103
 104         /** Max queue size for outbound packets */
 105         int queueLimit;
 106
 107         /**
 108          * Is this side blocked from accepting outbound packets?
 109          */
 110         bool queueFull() { return (sendQueue.size() == queueLimit); }
 111
 112         bool queueForSendTiming(PacketPtr pkt);
 113
 114         void finishSend(PacketBuffer *buf);
 115
 116         /**
 117          * Handle send event, scheduled when the packet at the head of
 118          * the outbound queue is ready to transmit (for timing
 119          * accesses only).
 120          */
 121         void trySend();
 122
 123         class SendEvent : public Event
 124         {
 125             BridgePort *port;
 126
 127           public:
 128             SendEvent(BridgePort *p)
 129                 : Event(&mainEventQueue), port(p) {}
 130
 131             virtual void process() { port->trySend(); }
 132
 133             virtual const char *description() { return "bridge send event"; }
 134         };
 135
 136         SendEvent sendEvent;
 137
 138       public:
 139
 140         /** Constructor for the BusPort.*/
 141         BridgePort(const std::string &_name,
 142                    Bridge *_bridge, BridgePort *_otherPort,
 143                    int _delay, int _queueLimit);
 144
 145       protected:
 146
 147         /** When receiving a timing request from the peer port,
 148             pass it to the bridge. */
 149         virtual bool recvTiming(PacketPtr pkt);
 150
 151         /** When receiving a retry request from the peer port,
 152             pass it to the bridge. */
 153         virtual void recvRetry();
 154
 155         /** When receiving a Atomic requestfrom the peer port,
 156             pass it to the bridge. */
 157         virtual Tick recvAtomic(PacketPtr pkt);
 158
 159         /** When receiving a Functional request from the peer port,
 160             pass it to the bridge. */
 161         virtual void recvFunctional(PacketPtr pkt);
 162
 163         /** When receiving a status changefrom the peer port,
 164             pass it to the bridge. */
 165         virtual void recvStatusChange(Status status);
 166
 167         /** When receiving a address range request the peer port,
 168             pass it to the bridge. */
 169         virtual void getDeviceAddressRanges(AddrRangeList &resp,
 170                                             AddrRangeList &snoop);
 171     };
 172
 173     BridgePort portA, portB;
 174
 175     /** If this bridge should acknowledge writes. */
 176     bool ackWrites;
 177
 178   public:
 179
 180     /** A function used to return the port associated with this bus object. */
 181     virtual Port *getPort(const std::string &if_name, int idx = -1);
 182
 183     virtual void init();
 184
 185     Bridge(const std::string &n, int qsa, int qsb, Tick _delay, int write_ack);
 186 };
 187
 188 #endif //__MEM_BUS_HH__