src/mem/tport.cc

   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  */
  30
  31 #include "mem/tport.hh"
  32
  33 void
  34 SimpleTimingPort::checkFunctional(PacketPtr pkt)
  35 {
  36     DeferredPacketIterator i = transmitList.begin();
  37     DeferredPacketIterator end = transmitList.end();
  38
  39     for (; i != end; ++i) {
  40         PacketPtr target = i->pkt;
  41         // If the target contains data, and it overlaps the
  42         // probed request, need to update data
  43         if (target->intersect(pkt)) {
  44             if (!fixPacket(pkt, target)) {
  45                 // fixPacket returns true for continue, false for done
  46                 return;
  47             }
  48         }
  49     }
  50 }
  51
  52 void
  53 SimpleTimingPort::recvFunctional(PacketPtr pkt)
  54 {
  55     checkFunctional(pkt);
  56
  57     // Just do an atomic access and throw away the returned latency
  58     if (pkt->result != Packet::Success)
  59         recvAtomic(pkt);
  60 }
  61
  62 bool
  63 SimpleTimingPort::recvTiming(PacketPtr pkt)
  64 {
  65     // If the device is only a slave, it should only be sending
  66     // responses, which should never get nacked.  There used to be
  67     // code to hanldle nacks here, but I'm pretty sure it didn't work
  68     // correctly with the drain code, so that would need to be fixed
  69     // if we ever added it back.
  70     assert(pkt->isRequest());
  71     assert(pkt->result == Packet::Unknown);
  72     bool needsResponse = pkt->needsResponse();
  73     Tick latency = recvAtomic(pkt);
  74     // turn packet around to go back to requester if response expected
  75     if (needsResponse) {
  76         // recvAtomic() should already have turned packet into atomic response
  77         assert(pkt->isResponse());
  78         pkt->convertAtomicToTimingResponse();
  79         schedSendTiming(pkt, curTick + latency);
  80     } else {
  81         delete pkt->req;
  82         delete pkt;
  83     }
  84     return true;
  85 }
  86
  87
  88 void
  89 SimpleTimingPort::schedSendTiming(PacketPtr pkt, Tick when)
  90 {
  91     assert(when > curTick);
  92
  93     // Nothing is on the list: add it and schedule an event
  94     if (transmitList.empty()) {
  95         assert(!sendEvent->scheduled());
  96         sendEvent->schedule(when);
  97         transmitList.push_back(DeferredPacket(when, pkt));
  98         return;
  99     }
 100
 101     // something is on the list and this belongs at the end
 102     if (when >= transmitList.back().tick) {
 103         transmitList.push_back(DeferredPacket(when, pkt));
 104         return;
 105     }
 106     // Something is on the list and this belongs somewhere else
 107     DeferredPacketIterator i = transmitList.begin();
 108     DeferredPacketIterator end = transmitList.end();
 109
 110     for (; i != end; ++i) {
 111         if (when < i->tick) {
 112             if (i == transmitList.begin()) {
 113                 //Inserting at begining, reschedule
 114                 sendEvent->reschedule(when);
 115             }
 116             transmitList.insert(i, DeferredPacket(when, pkt));
 117             return;
 118         }
 119     }
 120     assert(false); // should never get here
 121 }
 122
 123
 124 void
 125 SimpleTimingPort::sendDeferredPacket()
 126 {
 127     assert(deferredPacketReady());
 128     bool success = sendTiming(transmitList.front().pkt);
 129
 130     if (success) {
 131         //send successful, remove packet
 132         transmitList.pop_front();
 133         if (!transmitList.empty()) {
 134             Tick time = transmitList.front().tick;
 135             sendEvent->schedule(time <= curTick ? curTick+1 : time);
 136         }
 137
 138         if (transmitList.empty() && drainEvent) {
 139             drainEvent->process();
 140             drainEvent = NULL;
 141         }
 142     }
 143
 144     waitingOnRetry = !success;
 145
 146     if (waitingOnRetry) {
 147         DPRINTF(Bus, "Send failed, waiting on retry\n");
 148     }
 149 }
 150
 151
 152 void
 153 SimpleTimingPort::recvRetry()
 154 {
 155     DPRINTF(Bus, "Received retry\n");
 156     assert(waitingOnRetry);
 157     sendDeferredPacket();
 158 }
 159
 160
 161 void
 162 SimpleTimingPort::processSendEvent()
 163 {
 164     assert(!waitingOnRetry);
 165     sendDeferredPacket();
 166 }
 167
 168
 169 unsigned int
 170 SimpleTimingPort::drain(Event *de)
 171 {
 172     if (transmitList.size() == 0)
 173         return 0;
 174     drainEvent = de;
 175     return 1;
 176 }