bridge.cc revision 2665:a124942bacb8
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 Definition of a simple bus bridge without buffering. 35 */ 36 37#include <algorithm> 38 39#include "base/trace.hh" 40#include "mem/bridge.hh" 41#include "sim/builder.hh" 42 43Bridge::BridgePort::BridgePort(const std::string &_name, 44 Bridge *_bridge, BridgePort *_otherPort, 45 int _delay, int _queueLimit) 46 : Port(_name), bridge(_bridge), otherPort(_otherPort), 47 delay(_delay), outstandingResponses(0), 48 queueLimit(_queueLimit), sendEvent(this) 49{ 50} 51 52Bridge::Bridge(const std::string &n, int qsa, int qsb, 53 Tick _delay, int write_ack) 54 : MemObject(n), 55 portA(n + "-portA", this, &portB, _delay, qsa), 56 portB(n + "-portB", this, &portA, _delay, qsa), 57 ackWrites(write_ack) 58{ 59} 60 61Port * 62Bridge::getPort(const std::string &if_name) 63{ 64 BridgePort *port; 65 66 if (if_name == "side_a") 67 port = &portA; 68 else if (if_name == "side_b") 69 port = &portB; 70 else 71 return NULL; 72 73 if (port->getPeer() != NULL) 74 panic("bridge side %s already connected to.", if_name); 75 return port; 76} 77 78 79void 80Bridge::init() 81{ 82 // Make sure that both sides are connected to. 83 if (portA.getPeer() == NULL || portB.getPeer() == NULL) 84 panic("Both ports of bus bridge are not connected to a bus.\n"); 85} 86 87 88/** Function called by the port when the bus is receiving a Timing 89 * transaction.*/ 90bool 91Bridge::BridgePort::recvTiming(Packet *pkt) 92{ 93 DPRINTF(BusBridge, "recvTiming: src %d dest %d addr 0x%x\n", 94 pkt->getSrc(), pkt->getDest(), pkt->getAddr()); 95 96 return otherPort->queueForSendTiming(pkt); 97} 98 99 100bool 101Bridge::BridgePort::queueForSendTiming(Packet *pkt) 102{ 103 if (queueFull()) 104 return false; 105 106 if (pkt->isResponse()) { 107 // This is a response for a request we forwarded earlier. The 108 // corresponding PacketBuffer should be stored in the packet's 109 // senderState field. 110 PacketBuffer *buf = dynamic_cast<PacketBuffer*>(pkt->senderState); 111 assert(buf != NULL); 112 // set up new packet dest & senderState based on values saved 113 // from original request 114 buf->fixResponse(pkt); 115 DPRINTF(BusBridge, "restoring sender state: %#X, from packet buffer: %#X\n", 116 pkt->senderState, buf); 117 DPRINTF(BusBridge, " is response, new dest %d\n", pkt->getDest()); 118 delete buf; 119 } 120 121 Tick readyTime = curTick + delay; 122 PacketBuffer *buf = new PacketBuffer(pkt, readyTime); 123 DPRINTF(BusBridge, "old sender state: %#X, new sender state: %#X\n", 124 buf->origSenderState, buf); 125 126 // If we're about to put this packet at the head of the queue, we 127 // need to schedule an event to do the transmit. Otherwise there 128 // should already be an event scheduled for sending the head 129 // packet. 130 if (sendQueue.empty()) { 131 sendEvent.schedule(readyTime); 132 } 133 134 sendQueue.push_back(buf); 135 136 return true; 137} 138 139void 140Bridge::BridgePort::trySend() 141{ 142 assert(!sendQueue.empty()); 143 144 bool was_full = queueFull(); 145 146 PacketBuffer *buf = sendQueue.front(); 147 148 assert(buf->ready <= curTick); 149 150 Packet *pkt = buf->pkt; 151 152 DPRINTF(BusBridge, "trySend: origSrc %d dest %d addr 0x%x\n", 153 buf->origSrc, pkt->getDest(), pkt->getAddr()); 154 155 if (sendTiming(pkt)) { 156 // send successful 157 sendQueue.pop_front(); 158 buf->pkt = NULL; // we no longer own packet, so it's not safe to look at it 159 160 if (buf->expectResponse) { 161 // Must wait for response. We just need to count outstanding 162 // responses (in case we want to cap them); PacketBuffer 163 // pointer will be recovered on response. 164 ++outstandingResponses; 165 DPRINTF(BusBridge, " successful: awaiting response (%d)\n", 166 outstandingResponses); 167 } else { 168 // no response expected... deallocate packet buffer now. 169 DPRINTF(BusBridge, " successful: no response expected\n"); 170 delete buf; 171 } 172 173 // If there are more packets to send, schedule event to try again. 174 if (!sendQueue.empty()) { 175 buf = sendQueue.front(); 176 sendEvent.schedule(std::max(buf->ready, curTick + 1)); 177 } 178 // Let things start sending again 179 if (was_full) { 180 DPRINTF(BusBridge, "Queue was full, sending retry\n"); 181 otherPort->sendRetry(); 182 } 183 184 } else { 185 DPRINTF(BusBridge, " unsuccessful\n"); 186 } 187} 188 189 190void 191Bridge::BridgePort::recvRetry() 192{ 193 trySend(); 194} 195 196/** Function called by the port when the bus is receiving a Atomic 197 * transaction.*/ 198Tick 199Bridge::BridgePort::recvAtomic(Packet *pkt) 200{ 201 return otherPort->sendAtomic(pkt) + delay; 202} 203 204/** Function called by the port when the bus is receiving a Functional 205 * transaction.*/ 206void 207Bridge::BridgePort::recvFunctional(Packet *pkt) 208{ 209 std::list<PacketBuffer*>::iterator i; 210 bool pktContinue = true; 211 212 for (i = sendQueue.begin(); i != sendQueue.end(); ++i) { 213 if (pkt->intersect((*i)->pkt)) { 214 pktContinue &= fixPacket(pkt, (*i)->pkt); 215 } 216 } 217 218 if (pktContinue) { 219 otherPort->sendFunctional(pkt); 220 } 221} 222 223/** Function called by the port when the bus is receiving a status change.*/ 224void 225Bridge::BridgePort::recvStatusChange(Port::Status status) 226{ 227 otherPort->sendStatusChange(status); 228} 229 230void 231Bridge::BridgePort::getDeviceAddressRanges(AddrRangeList &resp, 232 AddrRangeList &snoop) 233{ 234 otherPort->getPeerAddressRanges(resp, snoop); 235} 236 237BEGIN_DECLARE_SIM_OBJECT_PARAMS(Bridge) 238 239 Param<int> queue_size_a; 240 Param<int> queue_size_b; 241 Param<Tick> delay; 242 Param<bool> write_ack; 243 244END_DECLARE_SIM_OBJECT_PARAMS(Bridge) 245 246BEGIN_INIT_SIM_OBJECT_PARAMS(Bridge) 247 248 INIT_PARAM(queue_size_a, "The size of the queue for data coming into side a"), 249 INIT_PARAM(queue_size_b, "The size of the queue for data coming into side b"), 250 INIT_PARAM(delay, "The miminum delay to cross this bridge"), 251 INIT_PARAM(write_ack, "Acknowledge any writes that are received.") 252 253END_INIT_SIM_OBJECT_PARAMS(Bridge) 254 255CREATE_SIM_OBJECT(Bridge) 256{ 257 return new Bridge(getInstanceName(), queue_size_a, queue_size_b, delay, 258 write_ack); 259} 260 261REGISTER_SIM_OBJECT("Bridge", Bridge) 262