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 Definition of a simple bus bridge without buffering.
  35  */
  36
  37 #include <algorithm>
  38
  39 #include "base/trace.hh"
  40 #include "mem/bridge.hh"
  41 #include "sim/builder.hh"
  42
  43 Bridge::BridgePort::BridgePort(const std::string &_name,
  44                                Bridge *_bridge, BridgePort *_otherPort,
  45                                int _delay, int _queueLimit)
  46     : Port(_name), bridge(_bridge), otherPort(_otherPort),
  47       delay(_delay), outstandingResponses(0),
  48       queueLimit(_queueLimit), sendEvent(this)
  49 {
  50 }
  51
  52 Bridge::Bridge(const std::string &n, int qsa, int qsb,
  53                Tick _delay, int write_ack)
  54     : MemObject(n),
  55       portA(n + "-portA", this, &portB, _delay, qsa),
  56       portB(n + "-portB", this, &portA, _delay, qsa),
  57       ackWrites(write_ack)
  58 {
  59 }
  60
  61 Port *
  62 Bridge::getPort(const std::string &if_name)
  63 {
  64     BridgePort *port;
  65
  66     if (if_name == "side_a")
  67         port = &portA;
  68     else if (if_name == "side_b")
  69         port = &portB;
  70     else
  71         return NULL;
  72
  73     if (port->getPeer() != NULL)
  74         panic("bridge side %s already connected to.", if_name);
  75     return port;
  76 }
  77
  78
  79 void
  80 Bridge::init()
  81 {
  82     // Make sure that both sides are connected to.
  83     if (portA.getPeer() == NULL || portB.getPeer() == NULL)
  84         panic("Both ports of bus bridge are not connected to a bus.\n");
  85 }
  86
  87
  88 /** Function called by the port when the bus is receiving a Timing
  89  * transaction.*/
  90 bool
  91 Bridge::BridgePort::recvTiming(Packet *pkt)
  92 {
  93     DPRINTF(BusBridge, "recvTiming: src %d dest %d addr 0x%x\n",
  94             pkt->getSrc(), pkt->getDest(), pkt->getAddr());
  95
  96     return otherPort->queueForSendTiming(pkt);
  97 }
  98
  99
 100 bool
 101 Bridge::BridgePort::queueForSendTiming(Packet *pkt)
 102 {
 103     if (queueFull())
 104         return false;
 105
 106    if (pkt->isResponse()) {
 107         // This is a response for a request we forwarded earlier.  The
 108         // corresponding PacketBuffer should be stored in the packet's
 109         // senderState field.
 110         PacketBuffer *buf = dynamic_cast<PacketBuffer*>(pkt->senderState);
 111         assert(buf != NULL);
 112         // set up new packet dest & senderState based on values saved
 113         // from original request
 114         buf->fixResponse(pkt);
 115         DPRINTF(BusBridge, "restoring  sender state: %#X, from packet buffer: %#X\n",
 116                         pkt->senderState, buf);
 117         DPRINTF(BusBridge, "  is response, new dest %d\n", pkt->getDest());
 118         delete buf;
 119     }
 120
 121     Tick readyTime = curTick + delay;
 122     PacketBuffer *buf = new PacketBuffer(pkt, readyTime);
 123     DPRINTF(BusBridge, "old sender state: %#X, new sender state: %#X\n",
 124             buf->origSenderState, buf);
 125
 126     // If we're about to put this packet at the head of the queue, we
 127     // need to schedule an event to do the transmit.  Otherwise there
 128     // should already be an event scheduled for sending the head
 129     // packet.
 130     if (sendQueue.empty()) {
 131         sendEvent.schedule(readyTime);
 132     }
 133
 134     sendQueue.push_back(buf);
 135
 136     return true;
 137 }
 138
 139 void
 140 Bridge::BridgePort::trySend()
 141 {
 142     assert(!sendQueue.empty());
 143
 144     bool was_full = queueFull();
 145
 146     PacketBuffer *buf = sendQueue.front();
 147
 148     assert(buf->ready <= curTick);
 149
 150     Packet *pkt = buf->pkt;
 151
 152     DPRINTF(BusBridge, "trySend: origSrc %d dest %d addr 0x%x\n",
 153             buf->origSrc, pkt->getDest(), pkt->getAddr());
 154
 155     if (sendTiming(pkt)) {
 156         // send successful
 157         sendQueue.pop_front();
 158         buf->pkt = NULL; // we no longer own packet, so it's not safe to look at it
 159
 160         if (buf->expectResponse) {
 161             // Must wait for response.  We just need to count outstanding
 162             // responses (in case we want to cap them); PacketBuffer
 163             // pointer will be recovered on response.
 164             ++outstandingResponses;
 165             DPRINTF(BusBridge, "  successful: awaiting response (%d)\n",
 166                     outstandingResponses);
 167         } else {
 168             // no response expected... deallocate packet buffer now.
 169             DPRINTF(BusBridge, "  successful: no response expected\n");
 170             delete buf;
 171         }
 172
 173         // If there are more packets to send, schedule event to try again.
 174         if (!sendQueue.empty()) {
 175             buf = sendQueue.front();
 176             sendEvent.schedule(std::max(buf->ready, curTick + 1));
 177         }
 178         // Let things start sending again
 179         if (was_full) {
 180           DPRINTF(BusBridge, "Queue was full, sending retry\n");
 181           otherPort->sendRetry();
 182         }
 183
 184     } else {
 185         DPRINTF(BusBridge, "  unsuccessful\n");
 186     }
 187 }
 188
 189
 190 void
 191 Bridge::BridgePort::recvRetry()
 192 {
 193     trySend();
 194 }
 195
 196 /** Function called by the port when the bus is receiving a Atomic
 197  * transaction.*/
 198 Tick
 199 Bridge::BridgePort::recvAtomic(Packet *pkt)
 200 {
 201     return otherPort->sendAtomic(pkt) + delay;
 202 }
 203
 204 /** Function called by the port when the bus is receiving a Functional
 205  * transaction.*/
 206 void
 207 Bridge::BridgePort::recvFunctional(Packet *pkt)
 208 {
 209     std::list<PacketBuffer*>::iterator i;
 210     bool pktContinue = true;
 211
 212     for (i = sendQueue.begin();  i != sendQueue.end(); ++i) {
 213         if (pkt->intersect((*i)->pkt)) {
 214             pktContinue &= fixPacket(pkt, (*i)->pkt);
 215         }
 216     }
 217
 218     if (pktContinue) {
 219         otherPort->sendFunctional(pkt);
 220     }
 221 }
 222
 223 /** Function called by the port when the bus is receiving a status change.*/
 224 void
 225 Bridge::BridgePort::recvStatusChange(Port::Status status)
 226 {
 227     otherPort->sendStatusChange(status);
 228 }
 229
 230 void
 231 Bridge::BridgePort::getDeviceAddressRanges(AddrRangeList &resp,
 232                                            AddrRangeList &snoop)
 233 {
 234     otherPort->getPeerAddressRanges(resp, snoop);
 235 }
 236
 237 BEGIN_DECLARE_SIM_OBJECT_PARAMS(Bridge)
 238
 239    Param<int> queue_size_a;
 240    Param<int> queue_size_b;
 241    Param<Tick> delay;
 242    Param<bool> write_ack;
 243
 244 END_DECLARE_SIM_OBJECT_PARAMS(Bridge)
 245
 246 BEGIN_INIT_SIM_OBJECT_PARAMS(Bridge)
 247
 248     INIT_PARAM(queue_size_a, "The size of the queue for data coming into side a"),
 249     INIT_PARAM(queue_size_b, "The size of the queue for data coming into side b"),
 250     INIT_PARAM(delay, "The miminum delay to cross this bridge"),
 251     INIT_PARAM(write_ack, "Acknowledge any writes that are received.")
 252
 253 END_INIT_SIM_OBJECT_PARAMS(Bridge)
 254
 255 CREATE_SIM_OBJECT(Bridge)
 256 {
 257     return new Bridge(getInstanceName(), queue_size_a, queue_size_b, delay,
 258             write_ack);
 259 }
 260
 261 REGISTER_SIM_OBJECT("Bridge", Bridge)