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::recvFunctional(PacketPtr pkt)
  35 {
  36     std::list<std::pair<Tick,PacketPtr> >::iterator i = transmitList.begin();
  37     std::list<std::pair<Tick,PacketPtr> >::iterator end = transmitList.end();
  38     bool done = false;
  39
  40     while (i != end && !done) {
  41         PacketPtr target = i->second;
  42         // If the target contains data, and it overlaps the
  43         // probed request, need to update data
  44         if (target->intersect(pkt))
  45             done = fixPacket(pkt, target);
  46
  47     }
  48
  49     //Then just do an atomic access and throw away the returned latency
  50     if (pkt->result != Packet::Success)
  51         recvAtomic(pkt);
  52 }
  53
  54 bool
  55 SimpleTimingPort::recvTiming(PacketPtr pkt)
  56 {
  57     // If the device is only a slave, it should only be sending
  58     // responses, which should never get nacked.  There used to be
  59     // code to hanldle nacks here, but I'm pretty sure it didn't work
  60     // correctly with the drain code, so that would need to be fixed
  61     // if we ever added it back.
  62     assert(pkt->result != Packet::Nacked);
  63     Tick latency = recvAtomic(pkt);
  64     // turn packet around to go back to requester if response expected
  65     if (pkt->needsResponse()) {
  66         pkt->makeTimingResponse();
  67         sendTiming(pkt, latency);
  68     }
  69     else {
  70         if (pkt->cmd != Packet::UpgradeReq)
  71         {
  72             delete pkt->req;
  73             delete pkt;
  74         }
  75     }
  76     return true;
  77 }
  78
  79 void
  80 SimpleTimingPort::recvRetry()
  81 {
  82     assert(!transmitList.empty());
  83     if (Port::sendTiming(transmitList.front().second)) {
  84         transmitList.pop_front();
  85         DPRINTF(Bus, "No Longer waiting on retry\n");
  86         if (!transmitList.empty()) {
  87             Tick time = transmitList.front().first;
  88             sendEvent.schedule(time <= curTick ? curTick+1 : time);
  89         }
  90     }
  91
  92     if (transmitList.empty() && drainEvent) {
  93         drainEvent->process();
  94         drainEvent = NULL;
  95     }
  96 }
  97
  98 void
  99 SimpleTimingPort::sendTiming(PacketPtr pkt, Tick time)
 100 {
 101     if (transmitList.empty()) {
 102         assert(!sendEvent.scheduled());
 103         sendEvent.schedule(curTick+time);
 104     }
 105     transmitList.push_back(std::pair<Tick,PacketPtr>(time+curTick,pkt));
 106 }
 107
 108 void
 109 SimpleTimingPort::SendEvent::process()
 110 {
 111     assert(port->transmitList.size());
 112     assert(port->transmitList.front().first <= curTick);
 113     if (port->Port::sendTiming(port->transmitList.front().second)) {
 114         //send successful, remove packet
 115         port->transmitList.pop_front();
 116         if (!port->transmitList.empty()) {
 117             Tick time = port->transmitList.front().first;
 118             schedule(time <= curTick ? curTick+1 : time);
 119         }
 120         if (port->transmitList.empty() && port->drainEvent) {
 121             port->drainEvent->process();
 122             port->drainEvent = NULL;
 123         }
 124         return;
 125     }
 126     // send unsuccessful (due to flow control).  Will get retry
 127     // callback later; save for then if not already
 128     DPRINTF(Bus, "Waiting on retry\n");
 129 }
 130
 131
 132 unsigned int
 133 SimpleTimingPort::drain(Event *de)
 134 {
 135     if (transmitList.size() == 0)
 136         return 0;
 137     drainEvent = de;
 138     return 1;
 139 }