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
  30 /**
  31  * @file Definition of a simple bus bridge without buffering.
  32  */
  33
  34 #include <algorithm>
  35
  36 #include "base/trace.hh"
  37 #include "mem/bridge.hh"
  38 #include "sim/builder.hh"
  39
  40 Bridge::BridgePort::BridgePort(const std::string &_name,
  41                                Bridge *_bridge, BridgePort *_otherPort,
  42                                int _delay, int _queueLimit)
  43     : Port(_name), bridge(_bridge), otherPort(_otherPort),
  44       delay(_delay), outstandingResponses(0),
  45       queueLimit(_queueLimit), sendEvent(this)
  46 {
  47 }
  48
  49 Bridge::Bridge(const std::string &n, int qsa, int qsb,
  50                Tick _delay, int write_ack)
  51     : MemObject(n),
  52       portA(n + "-portA", this, &portB, _delay, qsa),
  53       portB(n + "-portB", this, &portA, _delay, qsa),
  54       ackWrites(write_ack)
  55 {
  56 }
  57
  58 Port *
  59 Bridge::getPort(const std::string &if_name)
  60 {
  61     BridgePort *port;
  62
  63     if (if_name == "side_a")
  64         port = &portA;
  65     else if (if_name == "side_b")
  66         port = &portB;
  67     else
  68         return NULL;
  69
  70     if (port->getPeer() != NULL)
  71         panic("bridge side %s already connected to.", if_name);
  72     return port;
  73 }
  74
  75
  76 void
  77 Bridge::init()
  78 {
  79     // Make sure that both sides are connected to.
  80     if (portA.getPeer() == NULL || portB.getPeer() == NULL)
  81         panic("Both ports of bus bridge are not connected to a bus.\n");
  82 }
  83
  84
  85 /** Function called by the port when the bus is receiving a Timing
  86  * transaction.*/
  87 bool
  88 Bridge::BridgePort::recvTiming(Packet *pkt)
  89 {
  90     DPRINTF(BusBridge, "recvTiming: src %d dest %d addr 0x%x\n",
  91             pkt->getSrc(), pkt->getDest(), pkt->getAddr());
  92
  93     return otherPort->queueForSendTiming(pkt);
  94 }
  95
  96
  97 bool
  98 Bridge::BridgePort::queueForSendTiming(Packet *pkt)
  99 {
 100     if (queueFull())
 101         return false;
 102
 103    if (pkt->isResponse()) {
 104         // This is a response for a request we forwarded earlier.  The
 105         // corresponding PacketBuffer should be stored in the packet's
 106         // senderState field.
 107         PacketBuffer *buf = dynamic_cast<PacketBuffer*>(pkt->senderState);
 108         assert(buf != NULL);
 109         // set up new packet dest & senderState based on values saved
 110         // from original request
 111         buf->fixResponse(pkt);
 112         DPRINTF(BusBridge, "restoring  sender state: %#X, from packet buffer: %#X\n",
 113                         pkt->senderState, buf);
 114         DPRINTF(BusBridge, "  is response, new dest %d\n", pkt->getDest());
 115         delete buf;
 116     }
 117
 118     Tick readyTime = curTick + delay;
 119     PacketBuffer *buf = new PacketBuffer(pkt, readyTime);
 120     DPRINTF(BusBridge, "old sender state: %#X, new sender state: %#X\n",
 121             buf->origSenderState, buf);
 122
 123     // If we're about to put this packet at the head of the queue, we
 124     // need to schedule an event to do the transmit.  Otherwise there
 125     // should already be an event scheduled for sending the head
 126     // packet.
 127     if (sendQueue.empty()) {
 128         sendEvent.schedule(readyTime);
 129     }
 130
 131     sendQueue.push_back(buf);
 132
 133     return true;
 134 }
 135
 136 void
 137 Bridge::BridgePort::trySend()
 138 {
 139     assert(!sendQueue.empty());
 140
 141     bool was_full = queueFull();
 142
 143     PacketBuffer *buf = sendQueue.front();
 144
 145     assert(buf->ready <= curTick);
 146
 147     Packet *pkt = buf->pkt;
 148
 149     DPRINTF(BusBridge, "trySend: origSrc %d dest %d addr 0x%x\n",
 150             buf->origSrc, pkt->getDest(), pkt->getAddr());
 151
 152     if (sendTiming(pkt)) {
 153         // send successful
 154         sendQueue.pop_front();
 155         buf->pkt = NULL; // we no longer own packet, so it's not safe to look at it
 156
 157         if (buf->expectResponse) {
 158             // Must wait for response.  We just need to count outstanding
 159             // responses (in case we want to cap them); PacketBuffer
 160             // pointer will be recovered on response.
 161             ++outstandingResponses;
 162             DPRINTF(BusBridge, "  successful: awaiting response (%d)\n",
 163                     outstandingResponses);
 164         } else {
 165             // no response expected... deallocate packet buffer now.
 166             DPRINTF(BusBridge, "  successful: no response expected\n");
 167             delete buf;
 168         }
 169
 170         // If there are more packets to send, schedule event to try again.
 171         if (!sendQueue.empty()) {
 172             buf = sendQueue.front();
 173             sendEvent.schedule(std::max(buf->ready, curTick + 1));
 174         }
 175         // Let things start sending again
 176         if (was_full) {
 177           DPRINTF(BusBridge, "Queue was full, sending retry\n");
 178           otherPort->sendRetry();
 179         }
 180
 181     } else {
 182         DPRINTF(BusBridge, "  unsuccessful\n");
 183     }
 184 }
 185
 186
 187 void
 188 Bridge::BridgePort::recvRetry()
 189 {
 190     trySend();
 191 }
 192
 193 /** Function called by the port when the bus is receiving a Atomic
 194  * transaction.*/
 195 Tick
 196 Bridge::BridgePort::recvAtomic(Packet *pkt)
 197 {
 198     return otherPort->sendAtomic(pkt) + delay;
 199 }
 200
 201 /** Function called by the port when the bus is receiving a Functional
 202  * transaction.*/
 203 void
 204 Bridge::BridgePort::recvFunctional(Packet *pkt)
 205 {
 206     std::list<PacketBuffer*>::iterator i;
 207     bool pktContinue = true;
 208
 209     for (i = sendQueue.begin();  i != sendQueue.end(); ++i) {
 210         if (pkt->intersect((*i)->pkt)) {
 211             pktContinue &= fixPacket(pkt, (*i)->pkt);
 212         }
 213     }
 214
 215     if (pktContinue) {
 216         otherPort->sendFunctional(pkt);
 217     }
 218 }
 219
 220 /** Function called by the port when the bus is receiving a status change.*/
 221 void
 222 Bridge::BridgePort::recvStatusChange(Port::Status status)
 223 {
 224     otherPort->sendStatusChange(status);
 225 }
 226
 227 void
 228 Bridge::BridgePort::getDeviceAddressRanges(AddrRangeList &resp,
 229                                            AddrRangeList &snoop)
 230 {
 231     otherPort->getPeerAddressRanges(resp, snoop);
 232 }
 233
 234 BEGIN_DECLARE_SIM_OBJECT_PARAMS(Bridge)
 235
 236    Param<int> queue_size_a;
 237    Param<int> queue_size_b;
 238    Param<Tick> delay;
 239    Param<bool> write_ack;
 240
 241 END_DECLARE_SIM_OBJECT_PARAMS(Bridge)
 242
 243 BEGIN_INIT_SIM_OBJECT_PARAMS(Bridge)
 244
 245     INIT_PARAM(queue_size_a, "The size of the queue for data coming into side a"),
 246     INIT_PARAM(queue_size_b, "The size of the queue for data coming into side b"),
 247     INIT_PARAM(delay, "The miminum delay to cross this bridge"),
 248     INIT_PARAM(write_ack, "Acknowledge any writes that are received.")
 249
 250 END_INIT_SIM_OBJECT_PARAMS(Bridge)
 251
 252 CREATE_SIM_OBJECT(Bridge)
 253 {
 254     return new Bridge(getInstanceName(), queue_size_a, queue_size_b, delay,
 255             write_ack);
 256 }
 257
 258 REGISTER_SIM_OBJECT("Bridge", Bridge)