bridge.cc revision 8975:7f36d4436074
1/* 2 * Copyright (c) 2011-2012 ARM Limited 3 * All rights reserved 4 * 5 * The license below extends only to copyright in the software and shall 6 * not be construed as granting a license to any other intellectual 7 * property including but not limited to intellectual property relating 8 * to a hardware implementation of the functionality of the software 9 * licensed hereunder. You may use the software subject to the license 10 * terms below provided that you ensure that this notice is replicated 11 * unmodified and in its entirety in all distributions of the software, 12 * modified or unmodified, in source code or in binary form. 13 * 14 * Copyright (c) 2006 The Regents of The University of Michigan 15 * All rights reserved. 16 * 17 * Redistribution and use in source and binary forms, with or without 18 * modification, are permitted provided that the following conditions are 19 * met: redistributions of source code must retain the above copyright 20 * notice, this list of conditions and the following disclaimer; 21 * redistributions in binary form must reproduce the above copyright 22 * notice, this list of conditions and the following disclaimer in the 23 * documentation and/or other materials provided with the distribution; 24 * neither the name of the copyright holders nor the names of its 25 * contributors may be used to endorse or promote products derived from 26 * this software without specific prior written permission. 27 * 28 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 29 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 30 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 31 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 32 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 33 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 34 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 35 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 36 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 37 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 38 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 39 * 40 * Authors: Ali Saidi 41 * Steve Reinhardt 42 * Andreas Hansson 43 */ 44 45/** 46 * @file 47 * Implementation of a memory-mapped bus bridge that connects a master 48 * and a slave through a request and response queue. 49 */ 50 51#include "base/trace.hh" 52#include "debug/BusBridge.hh" 53#include "mem/bridge.hh" 54#include "params/Bridge.hh" 55 56Bridge::BridgeSlavePort::BridgeSlavePort(const std::string &_name, 57 Bridge* _bridge, 58 BridgeMasterPort& _masterPort, 59 int _delay, int _nack_delay, 60 int _resp_limit, 61 std::vector<Range<Addr> > _ranges) 62 : SlavePort(_name, _bridge), bridge(_bridge), masterPort(_masterPort), 63 delay(_delay), nackDelay(_nack_delay), 64 ranges(_ranges.begin(), _ranges.end()), 65 outstandingResponses(0), inRetry(false), 66 respQueueLimit(_resp_limit), sendEvent(*this) 67{ 68} 69 70Bridge::BridgeMasterPort::BridgeMasterPort(const std::string &_name, 71 Bridge* _bridge, 72 BridgeSlavePort& _slavePort, 73 int _delay, int _req_limit) 74 : MasterPort(_name, _bridge), bridge(_bridge), slavePort(_slavePort), 75 delay(_delay), inRetry(false), reqQueueLimit(_req_limit), 76 sendEvent(*this) 77{ 78} 79 80Bridge::Bridge(Params *p) 81 : MemObject(p), 82 slavePort(p->name + "-slave", this, masterPort, p->delay, 83 p->nack_delay, p->resp_size, p->ranges), 84 masterPort(p->name + "-master", this, slavePort, p->delay, p->req_size), 85 ackWrites(p->write_ack), _params(p) 86{ 87 if (ackWrites) 88 panic("No support for acknowledging writes\n"); 89} 90 91MasterPort& 92Bridge::getMasterPort(const std::string &if_name, int idx) 93{ 94 if (if_name == "master") 95 return masterPort; 96 else 97 // pass it along to our super class 98 return MemObject::getMasterPort(if_name, idx); 99} 100 101SlavePort& 102Bridge::getSlavePort(const std::string &if_name, int idx) 103{ 104 if (if_name == "slave") 105 return slavePort; 106 else 107 // pass it along to our super class 108 return MemObject::getSlavePort(if_name, idx); 109} 110 111void 112Bridge::init() 113{ 114 // make sure both sides are connected and have the same block size 115 if (!slavePort.isConnected() || !masterPort.isConnected()) 116 fatal("Both ports of bus bridge are not connected to a bus.\n"); 117 118 if (slavePort.peerBlockSize() != masterPort.peerBlockSize()) 119 fatal("Slave port size %d, master port size %d \n " \ 120 "Busses don't have the same block size... Not supported.\n", 121 slavePort.peerBlockSize(), masterPort.peerBlockSize()); 122 123 // notify the master side of our address ranges 124 slavePort.sendRangeChange(); 125} 126 127bool 128Bridge::BridgeSlavePort::respQueueFull() 129{ 130 return outstandingResponses == respQueueLimit; 131} 132 133bool 134Bridge::BridgeMasterPort::reqQueueFull() 135{ 136 return requestQueue.size() == reqQueueLimit; 137} 138 139bool 140Bridge::BridgeMasterPort::recvTimingResp(PacketPtr pkt) 141{ 142 // all checks are done when the request is accepted on the slave 143 // side, so we are guaranteed to have space for the response 144 DPRINTF(BusBridge, "recvTiming: response %s addr 0x%x\n", 145 pkt->cmdString(), pkt->getAddr()); 146 147 DPRINTF(BusBridge, "Request queue size: %d\n", requestQueue.size()); 148 149 slavePort.queueForSendTiming(pkt); 150 151 return true; 152} 153 154bool 155Bridge::BridgeSlavePort::recvTimingReq(PacketPtr pkt) 156{ 157 DPRINTF(BusBridge, "recvTiming: request %s addr 0x%x\n", 158 pkt->cmdString(), pkt->getAddr()); 159 160 DPRINTF(BusBridge, "Response queue size: %d outresp: %d\n", 161 responseQueue.size(), outstandingResponses); 162 163 if (masterPort.reqQueueFull()) { 164 DPRINTF(BusBridge, "Request queue full, nacking\n"); 165 nackRequest(pkt); 166 return true; 167 } 168 169 if (pkt->needsResponse()) { 170 if (respQueueFull()) { 171 DPRINTF(BusBridge, 172 "Response queue full, no space for response, nacking\n"); 173 DPRINTF(BusBridge, 174 "queue size: %d outstanding resp: %d\n", 175 responseQueue.size(), outstandingResponses); 176 nackRequest(pkt); 177 return true; 178 } else { 179 DPRINTF(BusBridge, "Request Needs response, reserving space\n"); 180 assert(outstandingResponses != respQueueLimit); 181 ++outstandingResponses; 182 } 183 } 184 185 masterPort.queueForSendTiming(pkt); 186 187 return true; 188} 189 190void 191Bridge::BridgeSlavePort::nackRequest(PacketPtr pkt) 192{ 193 // Nack the packet 194 pkt->makeTimingResponse(); 195 pkt->setNacked(); 196 197 // The Nack packets are stored in the response queue just like any 198 // other response, but they do not occupy any space as this is 199 // tracked by the outstandingResponses, this guarantees space for 200 // the Nack packets, but implicitly means we have an (unrealistic) 201 // unbounded Nack queue. 202 203 // put it on the list to send 204 Tick readyTime = curTick() + nackDelay; 205 PacketBuffer *buf = new PacketBuffer(pkt, readyTime, true); 206 207 // nothing on the list, add it and we're done 208 if (responseQueue.empty()) { 209 assert(!sendEvent.scheduled()); 210 bridge->schedule(sendEvent, readyTime); 211 responseQueue.push_back(buf); 212 return; 213 } 214 215 assert(sendEvent.scheduled() || inRetry); 216 217 // does it go at the end? 218 if (readyTime >= responseQueue.back()->ready) { 219 responseQueue.push_back(buf); 220 return; 221 } 222 223 // ok, somewhere in the middle, fun 224 std::list<PacketBuffer*>::iterator i = responseQueue.begin(); 225 std::list<PacketBuffer*>::iterator end = responseQueue.end(); 226 std::list<PacketBuffer*>::iterator begin = responseQueue.begin(); 227 bool done = false; 228 229 while (i != end && !done) { 230 if (readyTime < (*i)->ready) { 231 if (i == begin) 232 bridge->reschedule(sendEvent, readyTime); 233 responseQueue.insert(i,buf); 234 done = true; 235 } 236 i++; 237 } 238 assert(done); 239} 240 241void 242Bridge::BridgeMasterPort::queueForSendTiming(PacketPtr pkt) 243{ 244 Tick readyTime = curTick() + delay; 245 PacketBuffer *buf = new PacketBuffer(pkt, readyTime); 246 247 // If we're about to put this packet at the head of the queue, we 248 // need to schedule an event to do the transmit. Otherwise there 249 // should already be an event scheduled for sending the head 250 // packet. 251 if (requestQueue.empty()) { 252 bridge->schedule(sendEvent, readyTime); 253 } 254 255 assert(requestQueue.size() != reqQueueLimit); 256 257 requestQueue.push_back(buf); 258} 259 260 261void 262Bridge::BridgeSlavePort::queueForSendTiming(PacketPtr pkt) 263{ 264 // This is a response for a request we forwarded earlier. The 265 // corresponding PacketBuffer should be stored in the packet's 266 // senderState field. 267 PacketBuffer *buf = dynamic_cast<PacketBuffer*>(pkt->senderState); 268 assert(buf != NULL); 269 // set up new packet dest & senderState based on values saved 270 // from original request 271 buf->fixResponse(pkt); 272 273 // the bridge assumes that at least one bus has set the 274 // destination field of the packet 275 assert(pkt->isDestValid()); 276 DPRINTF(BusBridge, "response, new dest %d\n", pkt->getDest()); 277 delete buf; 278 279 Tick readyTime = curTick() + delay; 280 buf = new PacketBuffer(pkt, readyTime); 281 282 // If we're about to put this packet at the head of the queue, we 283 // need to schedule an event to do the transmit. Otherwise there 284 // should already be an event scheduled for sending the head 285 // packet. 286 if (responseQueue.empty()) { 287 bridge->schedule(sendEvent, readyTime); 288 } 289 responseQueue.push_back(buf); 290} 291 292void 293Bridge::BridgeMasterPort::trySend() 294{ 295 assert(!requestQueue.empty()); 296 297 PacketBuffer *buf = requestQueue.front(); 298 299 assert(buf->ready <= curTick()); 300 301 PacketPtr pkt = buf->pkt; 302 303 DPRINTF(BusBridge, "trySend: origSrc %d addr 0x%x\n", 304 buf->origSrc, pkt->getAddr()); 305 306 // If the send was successful, make sure sender state was set to NULL 307 // otherwise we could get a NACK back of a packet that didn't expect a 308 // response and we would try to use freed memory. 309 310 Packet::SenderState *old_sender_state = pkt->senderState; 311 if (!buf->expectResponse) 312 pkt->senderState = NULL; 313 314 if (sendTimingReq(pkt)) { 315 // send successful 316 requestQueue.pop_front(); 317 // we no longer own packet, so it's not safe to look at it 318 buf->pkt = NULL; 319 320 if (!buf->expectResponse) { 321 // no response expected... deallocate packet buffer now. 322 DPRINTF(BusBridge, " successful: no response expected\n"); 323 delete buf; 324 } 325 326 // If there are more packets to send, schedule event to try again. 327 if (!requestQueue.empty()) { 328 buf = requestQueue.front(); 329 DPRINTF(BusBridge, "Scheduling next send\n"); 330 bridge->schedule(sendEvent, std::max(buf->ready, curTick() + 1)); 331 } 332 } else { 333 DPRINTF(BusBridge, " unsuccessful\n"); 334 pkt->senderState = old_sender_state; 335 inRetry = true; 336 } 337 338 DPRINTF(BusBridge, "trySend: request queue size: %d\n", 339 requestQueue.size()); 340} 341 342void 343Bridge::BridgeSlavePort::trySend() 344{ 345 assert(!responseQueue.empty()); 346 347 PacketBuffer *buf = responseQueue.front(); 348 349 assert(buf->ready <= curTick()); 350 351 PacketPtr pkt = buf->pkt; 352 353 DPRINTF(BusBridge, "trySend: origSrc %d dest %d addr 0x%x\n", 354 buf->origSrc, pkt->getDest(), pkt->getAddr()); 355 356 bool was_nacked_here = buf->nackedHere; 357 358 // no need to worry about the sender state since we are not 359 // modifying it 360 361 if (sendTimingResp(pkt)) { 362 DPRINTF(BusBridge, " successful\n"); 363 // send successful 364 responseQueue.pop_front(); 365 // this is a response... deallocate packet buffer now. 366 delete buf; 367 368 if (!was_nacked_here) { 369 assert(outstandingResponses != 0); 370 --outstandingResponses; 371 } 372 373 // If there are more packets to send, schedule event to try again. 374 if (!responseQueue.empty()) { 375 buf = responseQueue.front(); 376 DPRINTF(BusBridge, "Scheduling next send\n"); 377 bridge->schedule(sendEvent, std::max(buf->ready, curTick() + 1)); 378 } 379 } else { 380 DPRINTF(BusBridge, " unsuccessful\n"); 381 inRetry = true; 382 } 383 384 DPRINTF(BusBridge, "trySend: queue size: %d outstanding resp: %d\n", 385 responseQueue.size(), outstandingResponses); 386} 387 388void 389Bridge::BridgeMasterPort::recvRetry() 390{ 391 inRetry = false; 392 Tick nextReady = requestQueue.front()->ready; 393 if (nextReady <= curTick()) 394 trySend(); 395 else 396 bridge->schedule(sendEvent, nextReady); 397} 398 399void 400Bridge::BridgeSlavePort::recvRetry() 401{ 402 inRetry = false; 403 Tick nextReady = responseQueue.front()->ready; 404 if (nextReady <= curTick()) 405 trySend(); 406 else 407 bridge->schedule(sendEvent, nextReady); 408} 409 410Tick 411Bridge::BridgeSlavePort::recvAtomic(PacketPtr pkt) 412{ 413 return delay + masterPort.sendAtomic(pkt); 414} 415 416void 417Bridge::BridgeSlavePort::recvFunctional(PacketPtr pkt) 418{ 419 std::list<PacketBuffer*>::iterator i; 420 421 pkt->pushLabel(name()); 422 423 // check the response queue 424 for (i = responseQueue.begin(); i != responseQueue.end(); ++i) { 425 if (pkt->checkFunctional((*i)->pkt)) { 426 pkt->makeResponse(); 427 return; 428 } 429 } 430 431 // also check the master port's request queue 432 if (masterPort.checkFunctional(pkt)) { 433 return; 434 } 435 436 pkt->popLabel(); 437 438 // fall through if pkt still not satisfied 439 masterPort.sendFunctional(pkt); 440} 441 442bool 443Bridge::BridgeMasterPort::checkFunctional(PacketPtr pkt) 444{ 445 bool found = false; 446 std::list<PacketBuffer*>::iterator i = requestQueue.begin(); 447 448 while(i != requestQueue.end() && !found) { 449 if (pkt->checkFunctional((*i)->pkt)) { 450 pkt->makeResponse(); 451 found = true; 452 } 453 ++i; 454 } 455 456 return found; 457} 458 459AddrRangeList 460Bridge::BridgeSlavePort::getAddrRanges() 461{ 462 return ranges; 463} 464 465Bridge * 466BridgeParams::create() 467{ 468 return new Bridge(this); 469} 470