bridge.cc revision 3293
1 2/* 3 * Copyright (c) 2006 The Regents of The University of Michigan 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions are 8 * met: redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer; 10 * redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution; 13 * neither the name of the copyright holders nor the names of its 14 * contributors may be used to endorse or promote products derived from 15 * this software without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 18 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 19 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 20 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 21 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 22 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 23 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 27 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 28 * 29 * Authors: Ali Saidi 30 * Steve Reinhardt 31 */ 32 33/** 34 * @file 35 * Definition of a simple bus bridge without buffering. 36 */ 37 38#include <algorithm> 39 40#include "base/trace.hh" 41#include "mem/bridge.hh" 42#include "sim/builder.hh" 43 44Bridge::BridgePort::BridgePort(const std::string &_name, 45 Bridge *_bridge, BridgePort *_otherPort, 46 int _delay, int _queueLimit) 47 : Port(_name), bridge(_bridge), otherPort(_otherPort), 48 delay(_delay), outstandingResponses(0), 49 queueLimit(_queueLimit), sendEvent(this) 50{ 51} 52 53Bridge::Bridge(const std::string &n, int qsa, int qsb, 54 Tick _delay, int write_ack) 55 : MemObject(n), 56 portA(n + "-portA", this, &portB, _delay, qsa), 57 portB(n + "-portB", this, &portA, _delay, qsa), 58 ackWrites(write_ack) 59{ 60} 61 62Port * 63Bridge::getPort(const std::string &if_name, int idx) 64{ 65 BridgePort *port; 66 67 if (if_name == "side_a") 68 port = &portA; 69 else if (if_name == "side_b") 70 port = &portB; 71 else 72 return NULL; 73 74 if (port->getPeer() != NULL) 75 panic("bridge side %s already connected to.", if_name); 76 return port; 77} 78 79 80void 81Bridge::init() 82{ 83 // Make sure that both sides are connected to. 84 if (portA.getPeer() == NULL || portB.getPeer() == NULL) 85 panic("Both ports of bus bridge are not connected to a bus.\n"); 86} 87 88 89/** Function called by the port when the bus is receiving a Timing 90 * transaction.*/ 91bool 92Bridge::BridgePort::recvTiming(Packet *pkt) 93{ 94 DPRINTF(BusBridge, "recvTiming: src %d dest %d addr 0x%x\n", 95 pkt->getSrc(), pkt->getDest(), pkt->getAddr()); 96 97 return otherPort->queueForSendTiming(pkt); 98} 99 100 101bool 102Bridge::BridgePort::queueForSendTiming(Packet *pkt) 103{ 104 if (queueFull()) 105 return false; 106 107 if (pkt->isResponse()) { 108 // This is a response for a request we forwarded earlier. The 109 // corresponding PacketBuffer should be stored in the packet's 110 // senderState field. 111 PacketBuffer *buf = dynamic_cast<PacketBuffer*>(pkt->senderState); 112 assert(buf != NULL); 113 // set up new packet dest & senderState based on values saved 114 // from original request 115 buf->fixResponse(pkt); 116 DPRINTF(BusBridge, "restoring sender state: %#X, from packet buffer: %#X\n", 117 pkt->senderState, buf); 118 DPRINTF(BusBridge, " is response, new dest %d\n", pkt->getDest()); 119 delete buf; 120 } 121 122 Tick readyTime = curTick + delay; 123 PacketBuffer *buf = new PacketBuffer(pkt, readyTime); 124 DPRINTF(BusBridge, "old sender state: %#X, new sender state: %#X\n", 125 buf->origSenderState, buf); 126 127 // If we're about to put this packet at the head of the queue, we 128 // need to schedule an event to do the transmit. Otherwise there 129 // should already be an event scheduled for sending the head 130 // packet. 131 if (sendQueue.empty()) { 132 sendEvent.schedule(readyTime); 133 } 134 135 sendQueue.push_back(buf); 136 137 return true; 138} 139 140void 141Bridge::BridgePort::trySend() 142{ 143 assert(!sendQueue.empty()); 144 145 bool was_full = queueFull(); 146 147 PacketBuffer *buf = sendQueue.front(); 148 149 assert(buf->ready <= curTick); 150 151 Packet *pkt = buf->pkt; 152 153 DPRINTF(BusBridge, "trySend: origSrc %d dest %d addr 0x%x\n", 154 buf->origSrc, pkt->getDest(), pkt->getAddr()); 155 156 pkt->flags &= ~SNOOP_COMMIT; //CLear it if it was set 157 if (sendTiming(pkt)) { 158 // send successful 159 sendQueue.pop_front(); 160 buf->pkt = NULL; // we no longer own packet, so it's not safe to look at it 161 162 if (buf->expectResponse) { 163 // Must wait for response. We just need to count outstanding 164 // responses (in case we want to cap them); PacketBuffer 165 // pointer will be recovered on response. 166 ++outstandingResponses; 167 DPRINTF(BusBridge, " successful: awaiting response (%d)\n", 168 outstandingResponses); 169 } else { 170 // no response expected... deallocate packet buffer now. 171 DPRINTF(BusBridge, " successful: no response expected\n"); 172 delete buf; 173 } 174 175 // If there are more packets to send, schedule event to try again. 176 if (!sendQueue.empty()) { 177 buf = sendQueue.front(); 178 sendEvent.schedule(std::max(buf->ready, curTick + 1)); 179 } 180 // Let things start sending again 181 if (was_full) { 182 DPRINTF(BusBridge, "Queue was full, sending retry\n"); 183 otherPort->sendRetry(); 184 } 185 186 } else { 187 DPRINTF(BusBridge, " unsuccessful\n"); 188 } 189} 190 191 192void 193Bridge::BridgePort::recvRetry() 194{ 195 trySend(); 196} 197 198/** Function called by the port when the bus is receiving a Atomic 199 * transaction.*/ 200Tick 201Bridge::BridgePort::recvAtomic(Packet *pkt) 202{ 203 return otherPort->sendAtomic(pkt) + delay; 204} 205 206/** Function called by the port when the bus is receiving a Functional 207 * transaction.*/ 208void 209Bridge::BridgePort::recvFunctional(Packet *pkt) 210{ 211 std::list<PacketBuffer*>::iterator i; 212 bool pktContinue = true; 213 214 for (i = sendQueue.begin(); i != sendQueue.end(); ++i) { 215 if (pkt->intersect((*i)->pkt)) { 216 pktContinue &= fixPacket(pkt, (*i)->pkt); 217 } 218 } 219 220 if (pktContinue) { 221 otherPort->sendFunctional(pkt); 222 } 223} 224 225/** Function called by the port when the bus is receiving a status change.*/ 226void 227Bridge::BridgePort::recvStatusChange(Port::Status status) 228{ 229 otherPort->sendStatusChange(status); 230} 231 232void 233Bridge::BridgePort::getDeviceAddressRanges(AddrRangeList &resp, 234 AddrRangeList &snoop) 235{ 236 otherPort->getPeerAddressRanges(resp, snoop); 237} 238 239BEGIN_DECLARE_SIM_OBJECT_PARAMS(Bridge) 240 241 Param<int> queue_size_a; 242 Param<int> queue_size_b; 243 Param<Tick> delay; 244 Param<bool> write_ack; 245 246END_DECLARE_SIM_OBJECT_PARAMS(Bridge) 247 248BEGIN_INIT_SIM_OBJECT_PARAMS(Bridge) 249 250 INIT_PARAM(queue_size_a, "The size of the queue for data coming into side a"), 251 INIT_PARAM(queue_size_b, "The size of the queue for data coming into side b"), 252 INIT_PARAM(delay, "The miminum delay to cross this bridge"), 253 INIT_PARAM(write_ack, "Acknowledge any writes that are received.") 254 255END_INIT_SIM_OBJECT_PARAMS(Bridge) 256 257CREATE_SIM_OBJECT(Bridge) 258{ 259 return new Bridge(getInstanceName(), queue_size_a, queue_size_b, delay, 260 write_ack); 261} 262 263REGISTER_SIM_OBJECT("Bridge", Bridge) 264