bridge.cc revision 4739
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 if (!(pkt->flags & SNOOP_COMMIT)) 116 return true; 117 118 119 DPRINTF(BusBridge, "recvTiming: src %d dest %d addr 0x%x\n", 120 pkt->getSrc(), pkt->getDest(), pkt->getAddr()); 121 122 DPRINTF(BusBridge, "Local queue size: %d outreq: %d outresp: %d\n", 123 sendQueue.size(), queuedRequests, outstandingResponses); 124 DPRINTF(BusBridge, "Remove queue size: %d outreq: %d outresp: %d\n", 125 otherPort->sendQueue.size(), otherPort->queuedRequests, 126 otherPort->outstandingResponses); 127 128 if (pkt->isRequest() && otherPort->reqQueueFull() && pkt->result != 129 Packet::Nacked) { 130 DPRINTF(BusBridge, "Remote queue full, nacking\n"); 131 nackRequest(pkt); 132 return true; 133 } 134 135 if (pkt->needsResponse() && pkt->result != Packet::Nacked) 136 if (respQueueFull()) { 137 DPRINTF(BusBridge, "Local queue full, no space for response, nacking\n"); 138 DPRINTF(BusBridge, "queue size: %d outreq: %d outstanding resp: %d\n", 139 sendQueue.size(), queuedRequests, outstandingResponses); 140 nackRequest(pkt); 141 return true; 142 } else { 143 DPRINTF(BusBridge, "Request Needs response, reserving space\n"); 144 ++outstandingResponses; 145 } 146 147 otherPort->queueForSendTiming(pkt); 148 149 return true; 150} 151 152void 153Bridge::BridgePort::nackRequest(PacketPtr pkt) 154{ 155 // Nack the packet 156 pkt->result = Packet::Nacked; 157 pkt->setDest(pkt->getSrc()); 158 159 //put it on the list to send 160 Tick readyTime = curTick + nackDelay; 161 PacketBuffer *buf = new PacketBuffer(pkt, readyTime, true); 162 163 // nothing on the list, add it and we're done 164 if (sendQueue.empty()) { 165 assert(!sendEvent.scheduled()); 166 sendEvent.schedule(readyTime); 167 sendQueue.push_back(buf); 168 return; 169 } 170 171 assert(sendEvent.scheduled() || inRetry); 172 173 // does it go at the end? 174 if (readyTime >= sendQueue.back()->ready) { 175 sendQueue.push_back(buf); 176 return; 177 } 178 179 // ok, somewhere in the middle, fun 180 std::list<PacketBuffer*>::iterator i = sendQueue.begin(); 181 std::list<PacketBuffer*>::iterator end = sendQueue.end(); 182 std::list<PacketBuffer*>::iterator begin = sendQueue.begin(); 183 bool done = false; 184 185 while (i != end && !done) { 186 if (readyTime < (*i)->ready) { 187 if (i == begin) 188 sendEvent.reschedule(readyTime); 189 sendQueue.insert(i,buf); 190 done = true; 191 } 192 i++; 193 } 194 assert(done); 195} 196 197 198void 199Bridge::BridgePort::queueForSendTiming(PacketPtr pkt) 200{ 201 if (pkt->isResponse() || pkt->result == Packet::Nacked) { 202 // This is a response for a request we forwarded earlier. The 203 // corresponding PacketBuffer should be stored in the packet's 204 // senderState field. 205 PacketBuffer *buf = dynamic_cast<PacketBuffer*>(pkt->senderState); 206 assert(buf != NULL); 207 // set up new packet dest & senderState based on values saved 208 // from original request 209 buf->fixResponse(pkt); 210 211 // Check if this packet was expecting a response and it's a nacked 212 // packet, in which case we will never being seeing it 213 if (buf->expectResponse && pkt->result == Packet::Nacked) 214 --outstandingResponses; 215 216 DPRINTF(BusBridge, "response, new dest %d\n", pkt->getDest()); 217 delete buf; 218 } 219 220 221 if (pkt->isRequest() && pkt->result != Packet::Nacked) { 222 ++queuedRequests; 223 } 224 225 226 227 Tick readyTime = curTick + delay; 228 PacketBuffer *buf = new PacketBuffer(pkt, readyTime); 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 pkt->flags &= ~SNOOP_COMMIT; //CLear it if it was set 252 253 // Ugly! @todo When multilevel coherence works this will be removed 254 if (pkt->cmd == MemCmd::WriteInvalidateReq && fixPartialWrite && 255 pkt->result != Packet::Nacked) { 256 PacketPtr funcPkt = new Packet(pkt->req, MemCmd::WriteReq, 257 Packet::Broadcast); 258 funcPkt->dataStatic(pkt->getPtr<uint8_t>()); 259 sendFunctional(funcPkt); 260 pkt->cmd = MemCmd::WriteReq; 261 delete funcPkt; 262 } 263 264 DPRINTF(BusBridge, "trySend: origSrc %d dest %d addr 0x%x\n", 265 buf->origSrc, pkt->getDest(), pkt->getAddr()); 266 267 bool wasReq = pkt->isRequest(); 268 bool wasNacked = pkt->result == Packet::Nacked; 269 270 if (sendTiming(pkt)) { 271 // send successful 272 sendQueue.pop_front(); 273 buf->pkt = NULL; // we no longer own packet, so it's not safe to look at it 274 275 if (buf->expectResponse) { 276 // Must wait for response 277 DPRINTF(BusBridge, " successful: awaiting response (%d)\n", 278 outstandingResponses); 279 } else { 280 // no response expected... deallocate packet buffer now. 281 DPRINTF(BusBridge, " successful: no response expected\n"); 282 delete buf; 283 } 284 285 if (!wasNacked) { 286 if (wasReq) 287 --queuedRequests; 288 else 289 --outstandingResponses; 290 } 291 292 // If there are more packets to send, schedule event to try again. 293 if (!sendQueue.empty()) { 294 buf = sendQueue.front(); 295 DPRINTF(BusBridge, "Scheduling next send\n"); 296 sendEvent.schedule(std::max(buf->ready, curTick + 1)); 297 } 298 } else { 299 DPRINTF(BusBridge, " unsuccessful\n"); 300 inRetry = true; 301 } 302 DPRINTF(BusBridge, "trySend: queue size: %d outreq: %d outstanding resp: %d\n", 303 sendQueue.size(), queuedRequests, outstandingResponses); 304} 305 306 307void 308Bridge::BridgePort::recvRetry() 309{ 310 inRetry = false; 311 Tick nextReady = sendQueue.front()->ready; 312 if (nextReady <= curTick) 313 trySend(); 314 else 315 sendEvent.schedule(nextReady); 316} 317 318/** Function called by the port when the bus is receiving a Atomic 319 * transaction.*/ 320Tick 321Bridge::BridgePort::recvAtomic(PacketPtr pkt) 322{ 323 // fix partial atomic writes... similar to the timing code that does the 324 // same... will be removed once our code gets this right 325 if (pkt->cmd == MemCmd::WriteInvalidateReq && fixPartialWrite) { 326 327 PacketPtr funcPkt = new Packet(pkt->req, MemCmd::WriteReq, 328 Packet::Broadcast); 329 funcPkt->dataStatic(pkt->getPtr<uint8_t>()); 330 otherPort->sendFunctional(funcPkt); 331 delete funcPkt; 332 pkt->cmd = MemCmd::WriteReq; 333 } 334 return delay + otherPort->sendAtomic(pkt); 335} 336 337/** Function called by the port when the bus is receiving a Functional 338 * transaction.*/ 339void 340Bridge::BridgePort::recvFunctional(PacketPtr pkt) 341{ 342 std::list<PacketBuffer*>::iterator i; 343 bool pktContinue = true; 344 345 for (i = sendQueue.begin(); i != sendQueue.end(); ++i) { 346 if (pkt->intersect((*i)->pkt)) { 347 pktContinue &= fixPacket(pkt, (*i)->pkt); 348 } 349 } 350 351 if (pktContinue) { 352 otherPort->sendFunctional(pkt); 353 } 354} 355 356/** Function called by the port when the bus is receiving a status change.*/ 357void 358Bridge::BridgePort::recvStatusChange(Port::Status status) 359{ 360 otherPort->sendStatusChange(status); 361} 362 363void 364Bridge::BridgePort::getDeviceAddressRanges(AddrRangeList &resp, 365 bool &snoop) 366{ 367 otherPort->getPeerAddressRanges(resp, snoop); 368} 369 370BEGIN_DECLARE_SIM_OBJECT_PARAMS(Bridge) 371 372 Param<int> req_size_a; 373 Param<int> req_size_b; 374 Param<int> resp_size_a; 375 Param<int> resp_size_b; 376 Param<Tick> delay; 377 Param<Tick> nack_delay; 378 Param<bool> write_ack; 379 Param<bool> fix_partial_write_a; 380 Param<bool> fix_partial_write_b; 381 382END_DECLARE_SIM_OBJECT_PARAMS(Bridge) 383 384BEGIN_INIT_SIM_OBJECT_PARAMS(Bridge) 385 386 INIT_PARAM(req_size_a, "The size of the queue for requests coming into side a"), 387 INIT_PARAM(req_size_b, "The size of the queue for requests coming into side b"), 388 INIT_PARAM(resp_size_a, "The size of the queue for responses coming into side a"), 389 INIT_PARAM(resp_size_b, "The size of the queue for responses coming into side b"), 390 INIT_PARAM(delay, "The miminum delay to cross this bridge"), 391 INIT_PARAM(nack_delay, "The minimum delay to nack a packet"), 392 INIT_PARAM(write_ack, "Acknowledge any writes that are received."), 393 INIT_PARAM(fix_partial_write_a, "Fixup any partial block writes that are received"), 394 INIT_PARAM(fix_partial_write_b, "Fixup any partial block writes that are received") 395 396END_INIT_SIM_OBJECT_PARAMS(Bridge) 397 398CREATE_SIM_OBJECT(Bridge) 399{ 400 Bridge::Params *p = new Bridge::Params; 401 p->name = getInstanceName(); 402 p->req_size_a = req_size_a; 403 p->req_size_b = req_size_b; 404 p->resp_size_a = resp_size_a; 405 p->resp_size_b = resp_size_b; 406 p->delay = delay; 407 p->nack_delay = nack_delay; 408 p->write_ack = write_ack; 409 p->fix_partial_write_a = fix_partial_write_a; 410 p->fix_partial_write_b = fix_partial_write_b; 411 return new Bridge(p); 412} 413 414REGISTER_SIM_OBJECT("Bridge", Bridge) 415 416 417