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->result != Packet::Nacked);
  71     Tick latency = recvAtomic(pkt);
  72     // turn packet around to go back to requester if response expected
  73     if (pkt->needsResponse()) {
  74         pkt->makeTimingResponse();
  75         schedSendTiming(pkt, latency);
  76     }
  77     else if (pkt->cmd != MemCmd::UpgradeReq) {
  78         delete pkt->req;
  79         delete pkt;
  80     }
  81     return true;
  82 }
  83
  84
  85 void
  86 SimpleTimingPort::schedSendTiming(PacketPtr pkt, Tick when)
  87 {
  88     assert(when > curTick);
  89
  90     // Nothing is on the list: add it and schedule an event
  91     if (transmitList.empty()) {
  92         assert(!sendEvent->scheduled());
  93         sendEvent->schedule(when);
  94         transmitList.push_back(DeferredPacket(when, pkt));
  95         return;
  96     }
  97
  98     // something is on the list and this belongs at the end
  99     if (when >= transmitList.back().tick) {
 100         transmitList.push_back(DeferredPacket(when, pkt));
 101         return;
 102     }
 103     // Something is on the list and this belongs somewhere else
 104     DeferredPacketIterator i = transmitList.begin();
 105     DeferredPacketIterator end = transmitList.end();
 106
 107     for (; i != end; ++i) {
 108         if (when < i->tick) {
 109             if (i == transmitList.begin()) {
 110                 //Inserting at begining, reschedule
 111                 sendEvent->reschedule(when);
 112             }
 113             transmitList.insert(i, DeferredPacket(when, pkt));
 114             return;
 115         }
 116     }
 117     assert(false); // should never get here
 118 }
 119
 120
 121 void
 122 SimpleTimingPort::sendDeferredPacket()
 123 {
 124     assert(deferredPacketReady());
 125     bool success = sendTiming(transmitList.front().pkt);
 126
 127     if (success) {
 128         //send successful, remove packet
 129         transmitList.pop_front();
 130         if (!transmitList.empty()) {
 131             Tick time = transmitList.front().tick;
 132             sendEvent->schedule(time <= curTick ? curTick+1 : time);
 133         }
 134
 135         if (transmitList.empty() && drainEvent) {
 136             drainEvent->process();
 137             drainEvent = NULL;
 138         }
 139     }
 140
 141     waitingOnRetry = !success;
 142
 143     if (waitingOnRetry) {
 144         DPRINTF(Bus, "Send failed, waiting on retry\n");
 145     }
 146 }
 147
 148
 149 void
 150 SimpleTimingPort::recvRetry()
 151 {
 152     DPRINTF(Bus, "Received retry\n");
 153     assert(waitingOnRetry);
 154     sendDeferredPacket();
 155 }
 156
 157
 158 void
 159 SimpleTimingPort::processSendEvent()
 160 {
 161     assert(!waitingOnRetry);
 162     sendDeferredPacket();
 163 }
 164
 165
 166 unsigned int
 167 SimpleTimingPort::drain(Event *de)
 168 {
 169     if (transmitList.size() == 0)
 170         return 0;
 171     drainEvent = de;
 172     return 1;
 173 }