tport.cc revision 4911:3a0ee63f490c
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 33void 34SimpleTimingPort::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 (pkt->checkFunctional(target)) { 44 return; 45 } 46 } 47} 48 49void 50SimpleTimingPort::recvFunctional(PacketPtr pkt) 51{ 52 checkFunctional(pkt); 53 54 // Just do an atomic access and throw away the returned latency 55 if (!pkt->isResponse()) 56 recvAtomic(pkt); 57} 58 59bool 60SimpleTimingPort::recvTiming(PacketPtr pkt) 61{ 62 // If the device is only a slave, it should only be sending 63 // responses, which should never get nacked. There used to be 64 // code to hanldle nacks here, but I'm pretty sure it didn't work 65 // correctly with the drain code, so that would need to be fixed 66 // if we ever added it back. 67 assert(pkt->isRequest()); 68 69 if (pkt->memInhibitAsserted()) { 70 // snooper will supply based on copy of packet 71 // still target's responsibility to delete packet 72 delete pkt; 73 return true; 74 } 75 76 bool needsResponse = pkt->needsResponse(); 77 Tick latency = recvAtomic(pkt); 78 // turn packet around to go back to requester if response expected 79 if (needsResponse) { 80 // recvAtomic() should already have turned packet into 81 // atomic response 82 assert(pkt->isResponse()); 83 schedSendTiming(pkt, curTick + latency); 84 } else { 85 delete pkt->req; 86 delete pkt; 87 } 88 89 return true; 90} 91 92 93void 94SimpleTimingPort::schedSendTiming(PacketPtr pkt, Tick when) 95{ 96 assert(when > curTick); 97 98 // Nothing is on the list: add it and schedule an event 99 if (transmitList.empty() || when < transmitList.front().tick) { 100 transmitList.push_front(DeferredPacket(when, pkt)); 101 schedSendEvent(when); 102 return; 103 } 104 105 // list is non-empty and this is not the head, so event should 106 // already be scheduled 107 assert(waitingOnRetry || 108 (sendEvent->scheduled() && sendEvent->when() <= when)); 109 110 // list is non-empty & this belongs at the end 111 if (when >= transmitList.back().tick) { 112 transmitList.push_back(DeferredPacket(when, pkt)); 113 return; 114 } 115 116 // this belongs in the middle somewhere 117 DeferredPacketIterator i = transmitList.begin(); 118 i++; // already checked for insertion at front 119 DeferredPacketIterator end = transmitList.end(); 120 121 for (; i != end; ++i) { 122 if (when < i->tick) { 123 transmitList.insert(i, DeferredPacket(when, pkt)); 124 return; 125 } 126 } 127 assert(false); // should never get here 128} 129 130 131void 132SimpleTimingPort::sendDeferredPacket() 133{ 134 assert(deferredPacketReady()); 135 // take packet off list here; if recvTiming() on the other side 136 // calls sendTiming() back on us (like SimpleTimingCpu does), then 137 // we get confused by having a non-active packet on transmitList 138 DeferredPacket dp = transmitList.front(); 139 transmitList.pop_front(); 140 bool success = sendTiming(dp.pkt); 141 142 if (success) { 143 if (!transmitList.empty() && !sendEvent->scheduled()) { 144 Tick time = transmitList.front().tick; 145 sendEvent->schedule(time <= curTick ? curTick+1 : time); 146 } 147 148 if (transmitList.empty() && drainEvent) { 149 drainEvent->process(); 150 drainEvent = NULL; 151 } 152 } else { 153 // Unsuccessful, need to put back on transmitList. Callee 154 // should not have messed with it (since it didn't accept that 155 // packet), so we can just push it back on the front. 156 assert(!sendEvent->scheduled()); 157 transmitList.push_front(dp); 158 } 159 160 waitingOnRetry = !success; 161 162 if (waitingOnRetry) { 163 DPRINTF(Bus, "Send failed, waiting on retry\n"); 164 } 165} 166 167 168void 169SimpleTimingPort::recvRetry() 170{ 171 DPRINTF(Bus, "Received retry\n"); 172 assert(waitingOnRetry); 173 sendDeferredPacket(); 174} 175 176 177void 178SimpleTimingPort::processSendEvent() 179{ 180 assert(!waitingOnRetry); 181 sendDeferredPacket(); 182} 183 184 185unsigned int 186SimpleTimingPort::drain(Event *de) 187{ 188 if (transmitList.size() == 0) 189 return 0; 190 drainEvent = de; 191 return 1; 192} 193