src/mem/bridge.cc

   1
   2 /*
   3  * Copyright (c) 2006 The Regents of The University of Michigan
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions are
   8  * met: redistributions of source code must retain the above copyright
   9  * notice, this list of conditions and the following disclaimer;
  10  * redistributions in binary form must reproduce the above copyright
  11  * notice, this list of conditions and the following disclaimer in the
  12  * documentation and/or other materials provided with the distribution;
  13  * neither the name of the copyright holders nor the names of its
  14  * contributors may be used to endorse or promote products derived from
  15  * this software without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  18  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  19  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  20  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  21  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  22  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  23  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  24  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  25  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  26  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  27  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  28  *
  29  * Authors: Ali Saidi
  30  *          Steve Reinhardt
  31  */
  32
  33 /**
  34  * @file
  35  * Definition of a simple bus bridge without buffering.
  36  */
  37
  38 #include <algorithm>
  39
  40 #include "base/trace.hh"
  41 #include "mem/bridge.hh"
  42 #include "sim/builder.hh"
  43
  44 Bridge::BridgePort::BridgePort(const std::string &_name,
  45                                Bridge *_bridge, BridgePort *_otherPort,
  46                                int _delay, int _queueLimit)
  47     : Port(_name), bridge(_bridge), otherPort(_otherPort),
  48       delay(_delay), outstandingResponses(0),
  49       queueLimit(_queueLimit), sendEvent(this)
  50 {
  51 }
  52
  53 Bridge::Bridge(const std::string &n, int qsa, int qsb,
  54                Tick _delay, int write_ack)
  55     : MemObject(n),
  56       portA(n + "-portA", this, &portB, _delay, qsa),
  57       portB(n + "-portB", this, &portA, _delay, qsa),
  58       ackWrites(write_ack)
  59 {
  60 }
  61
  62 Port *
  63 Bridge::getPort(const std::string &if_name, int idx)
  64 {
  65     BridgePort *port;
  66
  67     if (if_name == "side_a")
  68         port = &portA;
  69     else if (if_name == "side_b")
  70         port = &portB;
  71     else
  72         return NULL;
  73
  74     if (port->getPeer() != NULL)
  75         panic("bridge side %s already connected to.", if_name);
  76     return port;
  77 }
  78
  79
  80 void
  81 Bridge::init()
  82 {
  83     // Make sure that both sides are connected to.
  84     if (portA.getPeer() == NULL || portB.getPeer() == NULL)
  85         panic("Both ports of bus bridge are not connected to a bus.\n");
  86 }
  87
  88
  89 /** Function called by the port when the bus is receiving a Timing
  90  * transaction.*/
  91 bool
  92 Bridge::BridgePort::recvTiming(Packet *pkt)
  93 {
  94     DPRINTF(BusBridge, "recvTiming: src %d dest %d addr 0x%x\n",
  95             pkt->getSrc(), pkt->getDest(), pkt->getAddr());
  96
  97     return otherPort->queueForSendTiming(pkt);
  98 }
  99
 100
 101 bool
 102 Bridge::BridgePort::queueForSendTiming(Packet *pkt)
 103 {
 104     if (queueFull())
 105         return false;
 106
 107    if (pkt->isResponse()) {
 108         // This is a response for a request we forwarded earlier.  The
 109         // corresponding PacketBuffer should be stored in the packet's
 110         // senderState field.
 111         PacketBuffer *buf = dynamic_cast<PacketBuffer*>(pkt->senderState);
 112         assert(buf != NULL);
 113         // set up new packet dest & senderState based on values saved
 114         // from original request
 115         buf->fixResponse(pkt);
 116         DPRINTF(BusBridge, "restoring  sender state: %#X, from packet buffer: %#X\n",
 117                         pkt->senderState, buf);
 118         DPRINTF(BusBridge, "  is response, new dest %d\n", pkt->getDest());
 119         delete buf;
 120     }
 121
 122     Tick readyTime = curTick + delay;
 123     PacketBuffer *buf = new PacketBuffer(pkt, readyTime);
 124     DPRINTF(BusBridge, "old sender state: %#X, new sender state: %#X\n",
 125             buf->origSenderState, buf);
 126
 127     // If we're about to put this packet at the head of the queue, we
 128     // need to schedule an event to do the transmit.  Otherwise there
 129     // should already be an event scheduled for sending the head
 130     // packet.
 131     if (sendQueue.empty()) {
 132         sendEvent.schedule(readyTime);
 133     }
 134
 135     sendQueue.push_back(buf);
 136
 137     return true;
 138 }
 139
 140 void
 141 Bridge::BridgePort::trySend()
 142 {
 143     assert(!sendQueue.empty());
 144
 145     bool was_full = queueFull();
 146
 147     PacketBuffer *buf = sendQueue.front();
 148
 149     assert(buf->ready <= curTick);
 150
 151     Packet *pkt = buf->pkt;
 152
 153     DPRINTF(BusBridge, "trySend: origSrc %d dest %d addr 0x%x\n",
 154             buf->origSrc, pkt->getDest(), pkt->getAddr());
 155
 156     if (sendTiming(pkt)) {
 157         // send successful
 158         sendQueue.pop_front();
 159         buf->pkt = NULL; // we no longer own packet, so it's not safe to look at it
 160
 161         if (buf->expectResponse) {
 162             // Must wait for response.  We just need to count outstanding
 163             // responses (in case we want to cap them); PacketBuffer
 164             // pointer will be recovered on response.
 165             ++outstandingResponses;
 166             DPRINTF(BusBridge, "  successful: awaiting response (%d)\n",
 167                     outstandingResponses);
 168         } else {
 169             // no response expected... deallocate packet buffer now.
 170             DPRINTF(BusBridge, "  successful: no response expected\n");
 171             delete buf;
 172         }
 173
 174         // If there are more packets to send, schedule event to try again.
 175         if (!sendQueue.empty()) {
 176             buf = sendQueue.front();
 177             sendEvent.schedule(std::max(buf->ready, curTick + 1));
 178         }
 179         // Let things start sending again
 180         if (was_full) {
 181           DPRINTF(BusBridge, "Queue was full, sending retry\n");
 182           otherPort->sendRetry();
 183         }
 184
 185     } else {
 186         DPRINTF(BusBridge, "  unsuccessful\n");
 187     }
 188 }
 189
 190
 191 void
 192 Bridge::BridgePort::recvRetry()
 193 {
 194     trySend();
 195 }
 196
 197 /** Function called by the port when the bus is receiving a Atomic
 198  * transaction.*/
 199 Tick
 200 Bridge::BridgePort::recvAtomic(Packet *pkt)
 201 {
 202     return otherPort->sendAtomic(pkt) + delay;
 203 }
 204
 205 /** Function called by the port when the bus is receiving a Functional
 206  * transaction.*/
 207 void
 208 Bridge::BridgePort::recvFunctional(Packet *pkt)
 209 {
 210     std::list<PacketBuffer*>::iterator i;
 211     bool pktContinue = true;
 212
 213     for (i = sendQueue.begin();  i != sendQueue.end(); ++i) {
 214         if (pkt->intersect((*i)->pkt)) {
 215             pktContinue &= fixPacket(pkt, (*i)->pkt);
 216         }
 217     }
 218
 219     if (pktContinue) {
 220         otherPort->sendFunctional(pkt);
 221     }
 222 }
 223
 224 /** Function called by the port when the bus is receiving a status change.*/
 225 void
 226 Bridge::BridgePort::recvStatusChange(Port::Status status)
 227 {
 228     otherPort->sendStatusChange(status);
 229 }
 230
 231 void
 232 Bridge::BridgePort::getDeviceAddressRanges(AddrRangeList &resp,
 233                                            AddrRangeList &snoop)
 234 {
 235     otherPort->getPeerAddressRanges(resp, snoop);
 236 }
 237
 238 BEGIN_DECLARE_SIM_OBJECT_PARAMS(Bridge)
 239
 240    Param<int> queue_size_a;
 241    Param<int> queue_size_b;
 242    Param<Tick> delay;
 243    Param<bool> write_ack;
 244
 245 END_DECLARE_SIM_OBJECT_PARAMS(Bridge)
 246
 247 BEGIN_INIT_SIM_OBJECT_PARAMS(Bridge)
 248
 249     INIT_PARAM(queue_size_a, "The size of the queue for data coming into side a"),
 250     INIT_PARAM(queue_size_b, "The size of the queue for data coming into side b"),
 251     INIT_PARAM(delay, "The miminum delay to cross this bridge"),
 252     INIT_PARAM(write_ack, "Acknowledge any writes that are received.")
 253
 254 END_INIT_SIM_OBJECT_PARAMS(Bridge)
 255
 256 CREATE_SIM_OBJECT(Bridge)
 257 {
 258     return new Bridge(getInstanceName(), queue_size_a, queue_size_b, delay,
 259             write_ack);
 260 }
 261
 262 REGISTER_SIM_OBJECT("Bridge", Bridge)