bridge.cc revision 4877
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 _nack_delay, int _req_limit, 47 int _resp_limit, bool fix_partial_write) 48 : Port(_name), bridge(_bridge), otherPort(_otherPort), 49 delay(_delay), nackDelay(_nack_delay), fixPartialWrite(fix_partial_write), 50 outstandingResponses(0), queuedRequests(0), inRetry(false), 51 reqQueueLimit(_req_limit), respQueueLimit(_resp_limit), sendEvent(this) 52{ 53} 54 55Bridge::Bridge(Params *p) 56 : MemObject(p->name), 57 portA(p->name + "-portA", this, &portB, p->delay, p->nack_delay, 58 p->req_size_a, p->resp_size_a, p->fix_partial_write_a), 59 portB(p->name + "-portB", this, &portA, p->delay, p->nack_delay, 60 p->req_size_b, p->resp_size_b, p->fix_partial_write_b), 61 ackWrites(p->write_ack), _params(p) 62{ 63 if (ackWrites) 64 panic("No support for acknowledging writes\n"); 65} 66 67Port * 68Bridge::getPort(const std::string &if_name, int idx) 69{ 70 BridgePort *port; 71 72 if (if_name == "side_a") 73 port = &portA; 74 else if (if_name == "side_b") 75 port = &portB; 76 else 77 return NULL; 78 79 if (port->getPeer() != NULL) 80 panic("bridge side %s already connected to.", if_name); 81 return port; 82} 83 84 85void 86Bridge::init() 87{ 88 // Make sure that both sides are connected to. 89 if (portA.getPeer() == NULL || portB.getPeer() == NULL) 90 fatal("Both ports of bus bridge are not connected to a bus.\n"); 91 92 if (portA.peerBlockSize() != portB.peerBlockSize()) 93 fatal("Busses don't have the same block size... Not supported.\n"); 94} 95 96bool 97Bridge::BridgePort::respQueueFull() 98{ 99 assert(outstandingResponses >= 0 && outstandingResponses <= respQueueLimit); 100 return outstandingResponses >= respQueueLimit; 101} 102 103bool 104Bridge::BridgePort::reqQueueFull() 105{ 106 assert(queuedRequests >= 0 && queuedRequests <= reqQueueLimit); 107 return queuedRequests >= reqQueueLimit; 108} 109 110/** Function called by the port when the bus is receiving a Timing 111 * transaction.*/ 112bool 113Bridge::BridgePort::recvTiming(PacketPtr pkt) 114{ 115 DPRINTF(BusBridge, "recvTiming: src %d dest %d addr 0x%x\n", 116 pkt->getSrc(), pkt->getDest(), pkt->getAddr()); 117 118 DPRINTF(BusBridge, "Local queue size: %d outreq: %d outresp: %d\n", 119 sendQueue.size(), queuedRequests, outstandingResponses); 120 DPRINTF(BusBridge, "Remove queue size: %d outreq: %d outresp: %d\n", 121 otherPort->sendQueue.size(), otherPort->queuedRequests, 122 otherPort->outstandingResponses); 123 124 if (pkt->isRequest() && otherPort->reqQueueFull() && !pkt->wasNacked()) { 125 DPRINTF(BusBridge, "Remote queue full, nacking\n"); 126 nackRequest(pkt); 127 return true; 128 } 129 130 if (pkt->needsResponse() && !pkt->wasNacked()) 131 if (respQueueFull()) { 132 DPRINTF(BusBridge, "Local queue full, no space for response, nacking\n"); 133 DPRINTF(BusBridge, "queue size: %d outreq: %d outstanding resp: %d\n", 134 sendQueue.size(), queuedRequests, outstandingResponses); 135 nackRequest(pkt); 136 return true; 137 } else { 138 DPRINTF(BusBridge, "Request Needs response, reserving space\n"); 139 ++outstandingResponses; 140 } 141 142 otherPort->queueForSendTiming(pkt); 143 144 return true; 145} 146 147void 148Bridge::BridgePort::nackRequest(PacketPtr pkt) 149{ 150 // Nack the packet 151 pkt->setNacked(); 152 pkt->setDest(pkt->getSrc()); 153 154 //put it on the list to send 155 Tick readyTime = curTick + nackDelay; 156 PacketBuffer *buf = new PacketBuffer(pkt, readyTime, true); 157 158 // nothing on the list, add it and we're done 159 if (sendQueue.empty()) { 160 assert(!sendEvent.scheduled()); 161 sendEvent.schedule(readyTime); 162 sendQueue.push_back(buf); 163 return; 164 } 165 166 assert(sendEvent.scheduled() || inRetry); 167 168 // does it go at the end? 169 if (readyTime >= sendQueue.back()->ready) { 170 sendQueue.push_back(buf); 171 return; 172 } 173 174 // ok, somewhere in the middle, fun 175 std::list<PacketBuffer*>::iterator i = sendQueue.begin(); 176 std::list<PacketBuffer*>::iterator end = sendQueue.end(); 177 std::list<PacketBuffer*>::iterator begin = sendQueue.begin(); 178 bool done = false; 179 180 while (i != end && !done) { 181 if (readyTime < (*i)->ready) { 182 if (i == begin) 183 sendEvent.reschedule(readyTime); 184 sendQueue.insert(i,buf); 185 done = true; 186 } 187 i++; 188 } 189 assert(done); 190} 191 192 193void 194Bridge::BridgePort::queueForSendTiming(PacketPtr pkt) 195{ 196 if (pkt->isResponse() || pkt->wasNacked()) { 197 // This is a response for a request we forwarded earlier. The 198 // corresponding PacketBuffer should be stored in the packet's 199 // senderState field. 200 PacketBuffer *buf = dynamic_cast<PacketBuffer*>(pkt->senderState); 201 assert(buf != NULL); 202 // set up new packet dest & senderState based on values saved 203 // from original request 204 buf->fixResponse(pkt); 205 206 // Check if this packet was expecting a response and it's a nacked 207 // packet, in which case we will never being seeing it 208 if (buf->expectResponse && pkt->wasNacked()) 209 --outstandingResponses; 210 211 212 DPRINTF(BusBridge, "restoring sender state: %#X, from packet buffer: %#X\n", 213 pkt->senderState, buf); 214 DPRINTF(BusBridge, " is response, new dest %d\n", pkt->getDest()); 215 delete buf; 216 } 217 218 219 if (pkt->isRequest() && !pkt->wasNacked()) { 220 ++queuedRequests; 221 } 222 223 224 225 Tick readyTime = curTick + delay; 226 PacketBuffer *buf = new PacketBuffer(pkt, readyTime); 227 DPRINTF(BusBridge, "old sender state: %#X, new sender state: %#X\n", 228 buf->origSenderState, buf); 229 230 // If we're about to put this packet at the head of the queue, we 231 // need to schedule an event to do the transmit. Otherwise there 232 // should already be an event scheduled for sending the head 233 // packet. 234 if (sendQueue.empty()) { 235 sendEvent.schedule(readyTime); 236 } 237 sendQueue.push_back(buf); 238} 239 240void 241Bridge::BridgePort::trySend() 242{ 243 assert(!sendQueue.empty()); 244 245 PacketBuffer *buf = sendQueue.front(); 246 247 assert(buf->ready <= curTick); 248 249 PacketPtr pkt = buf->pkt; 250 251 // Ugly! @todo When multilevel coherence works this will be removed 252 if (pkt->cmd == MemCmd::WriteInvalidateReq && fixPartialWrite && 253 !pkt->wasNacked()) { 254 PacketPtr funcPkt = new Packet(pkt->req, MemCmd::WriteReq, 255 Packet::Broadcast); 256 funcPkt->dataStatic(pkt->getPtr<uint8_t>()); 257 sendFunctional(funcPkt); 258 pkt->cmd = MemCmd::WriteReq; 259 delete funcPkt; 260 } 261 262 DPRINTF(BusBridge, "trySend: origSrc %d dest %d addr 0x%x\n", 263 buf->origSrc, pkt->getDest(), pkt->getAddr()); 264 265 bool wasReq = pkt->isRequest(); 266 bool wasNacked = pkt->wasNacked(); 267 268 if (sendTiming(pkt)) { 269 // send successful 270 sendQueue.pop_front(); 271 buf->pkt = NULL; // we no longer own packet, so it's not safe to look at it 272 273 if (buf->expectResponse) { 274 // Must wait for response 275 DPRINTF(BusBridge, " successful: awaiting response (%d)\n", 276 outstandingResponses); 277 } else { 278 // no response expected... deallocate packet buffer now. 279 DPRINTF(BusBridge, " successful: no response expected\n"); 280 delete buf; 281 } 282 283 if (!wasNacked) { 284 if (wasReq) 285 --queuedRequests; 286 else 287 --outstandingResponses; 288 } 289 290 // If there are more packets to send, schedule event to try again. 291 if (!sendQueue.empty()) { 292 buf = sendQueue.front(); 293 DPRINTF(BusBridge, "Scheduling next send\n"); 294 sendEvent.schedule(std::max(buf->ready, curTick + 1)); 295 } 296 } else { 297 DPRINTF(BusBridge, " unsuccessful\n"); 298 inRetry = true; 299 } 300 DPRINTF(BusBridge, "trySend: queue size: %d outreq: %d outstanding resp: %d\n", 301 sendQueue.size(), queuedRequests, outstandingResponses); 302} 303 304 305void 306Bridge::BridgePort::recvRetry() 307{ 308 inRetry = false; 309 Tick nextReady = sendQueue.front()->ready; 310 if (nextReady <= curTick) 311 trySend(); 312 else 313 sendEvent.schedule(nextReady); 314} 315 316/** Function called by the port when the bus is receiving a Atomic 317 * transaction.*/ 318Tick 319Bridge::BridgePort::recvAtomic(PacketPtr pkt) 320{ 321 // fix partial atomic writes... similar to the timing code that does the 322 // same... will be removed once our code gets this right 323 if (pkt->cmd == MemCmd::WriteInvalidateReq && fixPartialWrite) { 324 325 PacketPtr funcPkt = new Packet(pkt->req, MemCmd::WriteReq, 326 Packet::Broadcast); 327 funcPkt->dataStatic(pkt->getPtr<uint8_t>()); 328 otherPort->sendFunctional(funcPkt); 329 delete funcPkt; 330 pkt->cmd = MemCmd::WriteReq; 331 } 332 return delay + otherPort->sendAtomic(pkt); 333} 334 335/** Function called by the port when the bus is receiving a Functional 336 * transaction.*/ 337void 338Bridge::BridgePort::recvFunctional(PacketPtr pkt) 339{ 340 std::list<PacketBuffer*>::iterator i; 341 342 for (i = sendQueue.begin(); i != sendQueue.end(); ++i) { 343 if (pkt->checkFunctional((*i)->pkt)) 344 return; 345 } 346 347 // fall through if pkt still not satisfied 348 otherPort->sendFunctional(pkt); 349} 350 351/** Function called by the port when the bus is receiving a status change.*/ 352void 353Bridge::BridgePort::recvStatusChange(Port::Status status) 354{ 355 otherPort->sendStatusChange(status); 356} 357 358void 359Bridge::BridgePort::getDeviceAddressRanges(AddrRangeList &resp, 360 bool &snoop) 361{ 362 otherPort->getPeerAddressRanges(resp, snoop); 363 // we don't allow snooping across bridges 364 snoop = false; 365} 366 367BEGIN_DECLARE_SIM_OBJECT_PARAMS(Bridge) 368 369 Param<int> req_size_a; 370 Param<int> req_size_b; 371 Param<int> resp_size_a; 372 Param<int> resp_size_b; 373 Param<Tick> delay; 374 Param<Tick> nack_delay; 375 Param<bool> write_ack; 376 Param<bool> fix_partial_write_a; 377 Param<bool> fix_partial_write_b; 378 379END_DECLARE_SIM_OBJECT_PARAMS(Bridge) 380 381BEGIN_INIT_SIM_OBJECT_PARAMS(Bridge) 382 383 INIT_PARAM(req_size_a, "The size of the queue for requests coming into side a"), 384 INIT_PARAM(req_size_b, "The size of the queue for requests coming into side b"), 385 INIT_PARAM(resp_size_a, "The size of the queue for responses coming into side a"), 386 INIT_PARAM(resp_size_b, "The size of the queue for responses coming into side b"), 387 INIT_PARAM(delay, "The miminum delay to cross this bridge"), 388 INIT_PARAM(nack_delay, "The minimum delay to nack a packet"), 389 INIT_PARAM(write_ack, "Acknowledge any writes that are received."), 390 INIT_PARAM(fix_partial_write_a, "Fixup any partial block writes that are received"), 391 INIT_PARAM(fix_partial_write_b, "Fixup any partial block writes that are received") 392 393END_INIT_SIM_OBJECT_PARAMS(Bridge) 394 395CREATE_SIM_OBJECT(Bridge) 396{ 397 Bridge::Params *p = new Bridge::Params; 398 p->name = getInstanceName(); 399 p->req_size_a = req_size_a; 400 p->req_size_b = req_size_b; 401 p->resp_size_a = resp_size_a; 402 p->resp_size_b = resp_size_b; 403 p->delay = delay; 404 p->nack_delay = nack_delay; 405 p->write_ack = write_ack; 406 p->fix_partial_write_a = fix_partial_write_a; 407 p->fix_partial_write_b = fix_partial_write_b; 408 return new Bridge(p); 409} 410 411REGISTER_SIM_OBJECT("Bridge", Bridge) 412 413 414