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     while (i != end) {
  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         i++;
  51     }
  52 }
  53
  54 void
  55 SimpleTimingPort::recvFunctional(PacketPtr pkt)
  56 {
  57     checkFunctional(pkt);
  58
  59     // Just do an atomic access and throw away the returned latency
  60     if (pkt->result != Packet::Success)
  61         recvAtomic(pkt);
  62 }
  63
  64 bool
  65 SimpleTimingPort::recvTiming(PacketPtr pkt)
  66 {
  67     // If the device is only a slave, it should only be sending
  68     // responses, which should never get nacked.  There used to be
  69     // code to hanldle nacks here, but I'm pretty sure it didn't work
  70     // correctly with the drain code, so that would need to be fixed
  71     // if we ever added it back.
  72     assert(pkt->result != Packet::Nacked);
  73     Tick latency = recvAtomic(pkt);
  74     // turn packet around to go back to requester if response expected
  75     if (pkt->needsResponse()) {
  76         pkt->makeTimingResponse();
  77         sendTiming(pkt, latency);
  78     }
  79     else if (pkt->cmd != MemCmd::UpgradeReq) {
  80         delete pkt->req;
  81         delete pkt;
  82     }
  83     return true;
  84 }
  85
  86 void
  87 SimpleTimingPort::recvRetry()
  88 {
  89     assert(!transmitList.empty());
  90     if (Port::sendTiming(transmitList.front().pkt)) {
  91         transmitList.pop_front();
  92         DPRINTF(Bus, "No Longer waiting on retry\n");
  93         if (!transmitList.empty()) {
  94             Tick time = transmitList.front().tick;
  95             sendEvent->schedule(time <= curTick ? curTick+1 : time);
  96         }
  97     }
  98
  99     if (transmitList.empty() && drainEvent) {
 100         drainEvent->process();
 101         drainEvent = NULL;
 102     }
 103 }
 104
 105 void
 106 SimpleTimingPort::sendTiming(PacketPtr pkt, Tick time)
 107 {
 108     // Nothing is on the list: add it and schedule an event
 109     if (transmitList.empty()) {
 110         assert(!sendEvent->scheduled());
 111         sendEvent->schedule(curTick+time);
 112         transmitList.push_back(DeferredPacket(time+curTick, pkt));
 113         return;
 114     }
 115
 116     // something is on the list and this belongs at the end
 117     if (time+curTick >= transmitList.back().tick) {
 118         transmitList.push_back(DeferredPacket(time+curTick, pkt));
 119         return;
 120     }
 121     // Something is on the list and this belongs somewhere else
 122     DeferredPacketIterator i = transmitList.begin();
 123     DeferredPacketIterator end = transmitList.end();
 124     bool done = false;
 125
 126     while (i != end && !done) {
 127         if (time+curTick < i->tick) {
 128             if (i == transmitList.begin()) {
 129                 //Inserting at begining, reschedule
 130                 sendEvent->reschedule(time+curTick);
 131             }
 132             transmitList.insert(i, DeferredPacket(time+curTick, pkt));
 133             done = true;
 134         }
 135         i++;
 136     }
 137     assert(done);
 138 }
 139
 140 void
 141 SimpleTimingPort::processSendEvent()
 142 {
 143     assert(transmitList.size());
 144     assert(transmitList.front().tick <= curTick);
 145     if (Port::sendTiming(transmitList.front().pkt)) {
 146         //send successful, remove packet
 147         transmitList.pop_front();
 148         if (!transmitList.empty()) {
 149             Tick time = transmitList.front().tick;
 150             sendEvent->schedule(time <= curTick ? curTick+1 : time);
 151         }
 152         if (transmitList.empty() && drainEvent) {
 153             drainEvent->process();
 154             drainEvent = NULL;
 155         }
 156         return;
 157     }
 158     // send unsuccessful (due to flow control).  Will get retry
 159     // callback later; save for then if not already
 160     DPRINTF(Bus, "Waiting on retry\n");
 161 }
 162
 163
 164 unsigned int
 165 SimpleTimingPort::drain(Event *de)
 166 {
 167     if (transmitList.size() == 0)
 168         return 0;
 169     drainEvent = de;
 170     return 1;
 171 }