bridge.cc revision 4965
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/range_ops.hh" 41#include "base/trace.hh" 42#include "mem/bridge.hh" 43#include "params/Bridge.hh" 44 45Bridge::BridgePort::BridgePort(const std::string &_name, 46 Bridge *_bridge, BridgePort *_otherPort, 47 int _delay, int _nack_delay, int _req_limit, 48 int _resp_limit, 49 std::vector<Range<Addr> > filter_ranges) 50 : Port(_name), bridge(_bridge), otherPort(_otherPort), 51 delay(_delay), nackDelay(_nack_delay), filterRanges(filter_ranges), 52 outstandingResponses(0), queuedRequests(0), inRetry(false), 53 reqQueueLimit(_req_limit), respQueueLimit(_resp_limit), sendEvent(this) 54{ 55} 56 57Bridge::Bridge(Params *p) 58 : MemObject(p->name), 59 portA(p->name + "-portA", this, &portB, p->delay, p->nack_delay, 60 p->req_size_a, p->resp_size_a, p->filter_ranges_a), 61 portB(p->name + "-portB", this, &portA, p->delay, p->nack_delay, 62 p->req_size_b, p->resp_size_b, p->filter_ranges_b), 63 ackWrites(p->write_ack), _params(p) 64{ 65 if (ackWrites) 66 panic("No support for acknowledging writes\n"); 67} 68 69Port * 70Bridge::getPort(const std::string &if_name, int idx) 71{ 72 BridgePort *port; 73 74 if (if_name == "side_a") 75 port = &portA; 76 else if (if_name == "side_b") 77 port = &portB; 78 else 79 return NULL; 80 81 if (port->getPeer() != NULL) 82 panic("bridge side %s already connected to.", if_name); 83 return port; 84} 85 86 87void 88Bridge::init() 89{ 90 // Make sure that both sides are connected to. 91 if (portA.getPeer() == NULL || portB.getPeer() == NULL) 92 fatal("Both ports of bus bridge are not connected to a bus.\n"); 93 94 if (portA.peerBlockSize() != portB.peerBlockSize()) 95 fatal("Busses don't have the same block size... Not supported.\n"); 96} 97 98bool 99Bridge::BridgePort::respQueueFull() 100{ 101 assert(outstandingResponses >= 0 && outstandingResponses <= respQueueLimit); 102 return outstandingResponses >= respQueueLimit; 103} 104 105bool 106Bridge::BridgePort::reqQueueFull() 107{ 108 assert(queuedRequests >= 0 && queuedRequests <= reqQueueLimit); 109 return queuedRequests >= reqQueueLimit; 110} 111 112/** Function called by the port when the bus is receiving a Timing 113 * transaction.*/ 114bool 115Bridge::BridgePort::recvTiming(PacketPtr pkt) 116{ 117 DPRINTF(BusBridge, "recvTiming: src %d dest %d addr 0x%x\n", 118 pkt->getSrc(), pkt->getDest(), pkt->getAddr()); 119 120 DPRINTF(BusBridge, "Local queue size: %d outreq: %d outresp: %d\n", 121 sendQueue.size(), queuedRequests, outstandingResponses); 122 DPRINTF(BusBridge, "Remove queue size: %d outreq: %d outresp: %d\n", 123 otherPort->sendQueue.size(), otherPort->queuedRequests, 124 otherPort->outstandingResponses); 125 126 if (pkt->isRequest() && otherPort->reqQueueFull() && !pkt->wasNacked()) { 127 DPRINTF(BusBridge, "Remote queue full, nacking\n"); 128 nackRequest(pkt); 129 return true; 130 } 131 132 if (pkt->needsResponse() && !pkt->wasNacked()) 133 if (respQueueFull()) { 134 DPRINTF(BusBridge, "Local queue full, no space for response, nacking\n"); 135 DPRINTF(BusBridge, "queue size: %d outreq: %d outstanding resp: %d\n", 136 sendQueue.size(), queuedRequests, outstandingResponses); 137 nackRequest(pkt); 138 return true; 139 } else { 140 DPRINTF(BusBridge, "Request Needs response, reserving space\n"); 141 ++outstandingResponses; 142 } 143 144 otherPort->queueForSendTiming(pkt); 145 146 return true; 147} 148 149void 150Bridge::BridgePort::nackRequest(PacketPtr pkt) 151{ 152 // Nack the packet 153 pkt->setNacked(); 154 pkt->setDest(pkt->getSrc()); 155 156 //put it on the list to send 157 Tick readyTime = curTick + nackDelay; 158 PacketBuffer *buf = new PacketBuffer(pkt, readyTime, true); 159 160 // nothing on the list, add it and we're done 161 if (sendQueue.empty()) { 162 assert(!sendEvent.scheduled()); 163 sendEvent.schedule(readyTime); 164 sendQueue.push_back(buf); 165 return; 166 } 167 168 assert(sendEvent.scheduled() || inRetry); 169 170 // does it go at the end? 171 if (readyTime >= sendQueue.back()->ready) { 172 sendQueue.push_back(buf); 173 return; 174 } 175 176 // ok, somewhere in the middle, fun 177 std::list<PacketBuffer*>::iterator i = sendQueue.begin(); 178 std::list<PacketBuffer*>::iterator end = sendQueue.end(); 179 std::list<PacketBuffer*>::iterator begin = sendQueue.begin(); 180 bool done = false; 181 182 while (i != end && !done) { 183 if (readyTime < (*i)->ready) { 184 if (i == begin) 185 sendEvent.reschedule(readyTime); 186 sendQueue.insert(i,buf); 187 done = true; 188 } 189 i++; 190 } 191 assert(done); 192} 193 194 195void 196Bridge::BridgePort::queueForSendTiming(PacketPtr pkt) 197{ 198 if (pkt->isResponse() || pkt->wasNacked()) { 199 // This is a response for a request we forwarded earlier. The 200 // corresponding PacketBuffer should be stored in the packet's 201 // senderState field. 202 PacketBuffer *buf = dynamic_cast<PacketBuffer*>(pkt->senderState); 203 assert(buf != NULL); 204 // set up new packet dest & senderState based on values saved 205 // from original request 206 buf->fixResponse(pkt); 207 208 // Check if this packet was expecting a response and it's a nacked 209 // packet, in which case we will never being seeing it 210 if (buf->expectResponse && pkt->wasNacked()) 211 --outstandingResponses; 212 213 DPRINTF(BusBridge, "response, new dest %d\n", pkt->getDest()); 214 delete buf; 215 } 216 217 218 if (pkt->isRequest() && !pkt->wasNacked()) { 219 ++queuedRequests; 220 } 221 222 223 224 Tick readyTime = curTick + delay; 225 PacketBuffer *buf = new PacketBuffer(pkt, readyTime); 226 227 // If we're about to put this packet at the head of the queue, we 228 // need to schedule an event to do the transmit. Otherwise there 229 // should already be an event scheduled for sending the head 230 // packet. 231 if (sendQueue.empty()) { 232 sendEvent.schedule(readyTime); 233 } 234 sendQueue.push_back(buf); 235} 236 237void 238Bridge::BridgePort::trySend() 239{ 240 assert(!sendQueue.empty()); 241 242 PacketBuffer *buf = sendQueue.front(); 243 244 assert(buf->ready <= curTick); 245 246 PacketPtr pkt = buf->pkt; 247 248 DPRINTF(BusBridge, "trySend: origSrc %d dest %d addr 0x%x\n", 249 buf->origSrc, pkt->getDest(), pkt->getAddr()); 250 251 bool wasReq = pkt->isRequest(); 252 bool wasNacked = pkt->wasNacked(); 253 254 if (sendTiming(pkt)) { 255 // send successful 256 sendQueue.pop_front(); 257 buf->pkt = NULL; // we no longer own packet, so it's not safe to look at it 258 259 if (buf->expectResponse) { 260 // Must wait for response 261 DPRINTF(BusBridge, " successful: awaiting response (%d)\n", 262 outstandingResponses); 263 } else { 264 // no response expected... deallocate packet buffer now. 265 DPRINTF(BusBridge, " successful: no response expected\n"); 266 delete buf; 267 } 268 269 if (!wasNacked) { 270 if (wasReq) 271 --queuedRequests; 272 else 273 --outstandingResponses; 274 } 275 276 // If there are more packets to send, schedule event to try again. 277 if (!sendQueue.empty()) { 278 buf = sendQueue.front(); 279 DPRINTF(BusBridge, "Scheduling next send\n"); 280 sendEvent.schedule(std::max(buf->ready, curTick + 1)); 281 } 282 } else { 283 DPRINTF(BusBridge, " unsuccessful\n"); 284 inRetry = true; 285 } 286 DPRINTF(BusBridge, "trySend: queue size: %d outreq: %d outstanding resp: %d\n", 287 sendQueue.size(), queuedRequests, outstandingResponses); 288} 289 290 291void 292Bridge::BridgePort::recvRetry() 293{ 294 inRetry = false; 295 Tick nextReady = sendQueue.front()->ready; 296 if (nextReady <= curTick) 297 trySend(); 298 else 299 sendEvent.schedule(nextReady); 300} 301 302/** Function called by the port when the bus is receiving a Atomic 303 * transaction.*/ 304Tick 305Bridge::BridgePort::recvAtomic(PacketPtr pkt) 306{ 307 return delay + otherPort->sendAtomic(pkt); 308} 309 310/** Function called by the port when the bus is receiving a Functional 311 * transaction.*/ 312void 313Bridge::BridgePort::recvFunctional(PacketPtr pkt) 314{ 315 std::list<PacketBuffer*>::iterator i; 316 317 for (i = sendQueue.begin(); i != sendQueue.end(); ++i) { 318 if (pkt->checkFunctional((*i)->pkt)) 319 return; 320 } 321 322 // fall through if pkt still not satisfied 323 otherPort->sendFunctional(pkt); 324} 325 326/** Function called by the port when the bus is receiving a status change.*/ 327void 328Bridge::BridgePort::recvStatusChange(Port::Status status) 329{ 330 otherPort->sendStatusChange(status); 331} 332 333void 334Bridge::BridgePort::getDeviceAddressRanges(AddrRangeList &resp, 335 bool &snoop) 336{ 337 otherPort->getPeerAddressRanges(resp, snoop); 338 FilterRangeList(filterRanges, resp); 339 // we don't allow snooping across bridges 340 snoop = false; 341} 342 343Bridge * 344BridgeParams::create() 345{ 346 return new Bridge(this); 347} 348