bridge.cc revision 9786
1/* 2 * Copyright (c) 2011-2013 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/Bridge.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 Cycles _delay, int _resp_limit, 60 std::vector<AddrRange> _ranges) 61 : SlavePort(_name, &_bridge), bridge(_bridge), masterPort(_masterPort), 62 delay(_delay), ranges(_ranges.begin(), _ranges.end()), 63 outstandingResponses(0), retryReq(false), 64 respQueueLimit(_resp_limit), sendEvent(*this) 65{ 66} 67 68Bridge::BridgeMasterPort::BridgeMasterPort(const std::string& _name, 69 Bridge& _bridge, 70 BridgeSlavePort& _slavePort, 71 Cycles _delay, int _req_limit) 72 : MasterPort(_name, &_bridge), bridge(_bridge), slavePort(_slavePort), 73 delay(_delay), reqQueueLimit(_req_limit), sendEvent(*this) 74{ 75} 76 77Bridge::Bridge(Params *p) 78 : MemObject(p), 79 slavePort(p->name + ".slave", *this, masterPort, 80 ticksToCycles(p->delay), p->resp_size, p->ranges), 81 masterPort(p->name + ".master", *this, slavePort, 82 ticksToCycles(p->delay), p->req_size) 83{ 84} 85 86BaseMasterPort& 87Bridge::getMasterPort(const std::string &if_name, PortID idx) 88{ 89 if (if_name == "master") 90 return masterPort; 91 else 92 // pass it along to our super class 93 return MemObject::getMasterPort(if_name, idx); 94} 95 96BaseSlavePort& 97Bridge::getSlavePort(const std::string &if_name, PortID idx) 98{ 99 if (if_name == "slave") 100 return slavePort; 101 else 102 // pass it along to our super class 103 return MemObject::getSlavePort(if_name, idx); 104} 105 106void 107Bridge::init() 108{ 109 // make sure both sides are connected and have the same block size 110 if (!slavePort.isConnected() || !masterPort.isConnected()) 111 fatal("Both ports of bus bridge are not connected to a bus.\n"); 112 113 if (slavePort.peerBlockSize() != masterPort.peerBlockSize()) 114 fatal("Slave port size %d, master port size %d \n " \ 115 "Busses don't have the same block size... Not supported.\n", 116 slavePort.peerBlockSize(), masterPort.peerBlockSize()); 117 118 // notify the master side of our address ranges 119 slavePort.sendRangeChange(); 120} 121 122bool 123Bridge::BridgeSlavePort::respQueueFull() const 124{ 125 return outstandingResponses == respQueueLimit; 126} 127 128bool 129Bridge::BridgeMasterPort::reqQueueFull() const 130{ 131 return transmitList.size() == reqQueueLimit; 132} 133 134bool 135Bridge::BridgeMasterPort::recvTimingResp(PacketPtr pkt) 136{ 137 // all checks are done when the request is accepted on the slave 138 // side, so we are guaranteed to have space for the response 139 DPRINTF(Bridge, "recvTimingResp: %s addr 0x%x\n", 140 pkt->cmdString(), pkt->getAddr()); 141 142 DPRINTF(Bridge, "Request queue size: %d\n", transmitList.size()); 143 144 // @todo: We need to pay for this and not just zero it out 145 pkt->busFirstWordDelay = pkt->busLastWordDelay = 0; 146 147 slavePort.schedTimingResp(pkt, bridge.clockEdge(delay)); 148 149 return true; 150} 151 152bool 153Bridge::BridgeSlavePort::recvTimingReq(PacketPtr pkt) 154{ 155 DPRINTF(Bridge, "recvTimingReq: %s addr 0x%x\n", 156 pkt->cmdString(), pkt->getAddr()); 157 158 // we should not see a timing request if we are already in a retry 159 assert(!retryReq); 160 161 DPRINTF(Bridge, "Response queue size: %d outresp: %d\n", 162 transmitList.size(), outstandingResponses); 163 164 // if the request queue is full then there is no hope 165 if (masterPort.reqQueueFull()) { 166 DPRINTF(Bridge, "Request queue full\n"); 167 retryReq = true; 168 } else { 169 // look at the response queue if we expect to see a response 170 bool expects_response = pkt->needsResponse() && 171 !pkt->memInhibitAsserted(); 172 if (expects_response) { 173 if (respQueueFull()) { 174 DPRINTF(Bridge, "Response queue full\n"); 175 retryReq = true; 176 } else { 177 // ok to send the request with space for the response 178 DPRINTF(Bridge, "Reserving space for response\n"); 179 assert(outstandingResponses != respQueueLimit); 180 ++outstandingResponses; 181 182 // no need to set retryReq to false as this is already the 183 // case 184 } 185 } 186 187 if (!retryReq) { 188 // @todo: We need to pay for this and not just zero it out 189 pkt->busFirstWordDelay = pkt->busLastWordDelay = 0; 190 191 masterPort.schedTimingReq(pkt, bridge.clockEdge(delay)); 192 } 193 } 194 195 // remember that we are now stalling a packet and that we have to 196 // tell the sending master to retry once space becomes available, 197 // we make no distinction whether the stalling is due to the 198 // request queue or response queue being full 199 return !retryReq; 200} 201 202void 203Bridge::BridgeSlavePort::retryStalledReq() 204{ 205 if (retryReq) { 206 DPRINTF(Bridge, "Request waiting for retry, now retrying\n"); 207 retryReq = false; 208 sendRetry(); 209 } 210} 211 212void 213Bridge::BridgeMasterPort::schedTimingReq(PacketPtr pkt, Tick when) 214{ 215 // If we expect to see a response, we need to restore the source 216 // and destination field that is potentially changed by a second 217 // bus 218 if (!pkt->memInhibitAsserted() && pkt->needsResponse()) { 219 // Update the sender state so we can deal with the response 220 // appropriately 221 pkt->pushSenderState(new RequestState(pkt->getSrc())); 222 } 223 224 // If we're about to put this packet at the head of the queue, we 225 // need to schedule an event to do the transmit. Otherwise there 226 // should already be an event scheduled for sending the head 227 // packet. 228 if (transmitList.empty()) { 229 bridge.schedule(sendEvent, when); 230 } 231 232 assert(transmitList.size() != reqQueueLimit); 233 234 transmitList.push_back(DeferredPacket(pkt, when)); 235} 236 237 238void 239Bridge::BridgeSlavePort::schedTimingResp(PacketPtr pkt, Tick when) 240{ 241 // This is a response for a request we forwarded earlier. The 242 // corresponding request state should be stored in the packet's 243 // senderState field. 244 RequestState *req_state = 245 dynamic_cast<RequestState*>(pkt->popSenderState()); 246 assert(req_state != NULL); 247 pkt->setDest(req_state->origSrc); 248 delete req_state; 249 250 // the bridge assumes that at least one bus has set the 251 // destination field of the packet 252 assert(pkt->isDestValid()); 253 DPRINTF(Bridge, "response, new dest %d\n", pkt->getDest()); 254 255 // If we're about to put this packet at the head of the queue, we 256 // need to schedule an event to do the transmit. Otherwise there 257 // should already be an event scheduled for sending the head 258 // packet. 259 if (transmitList.empty()) { 260 bridge.schedule(sendEvent, when); 261 } 262 263 transmitList.push_back(DeferredPacket(pkt, when)); 264} 265 266void 267Bridge::BridgeMasterPort::trySendTiming() 268{ 269 assert(!transmitList.empty()); 270 271 DeferredPacket req = transmitList.front(); 272 273 assert(req.tick <= curTick()); 274 275 PacketPtr pkt = req.pkt; 276 277 DPRINTF(Bridge, "trySend request addr 0x%x, queue size %d\n", 278 pkt->getAddr(), transmitList.size()); 279 280 if (sendTimingReq(pkt)) { 281 // send successful 282 transmitList.pop_front(); 283 DPRINTF(Bridge, "trySend request successful\n"); 284 285 // If there are more packets to send, schedule event to try again. 286 if (!transmitList.empty()) { 287 DeferredPacket next_req = transmitList.front(); 288 DPRINTF(Bridge, "Scheduling next send\n"); 289 bridge.schedule(sendEvent, std::max(next_req.tick, 290 bridge.clockEdge())); 291 } 292 293 // if we have stalled a request due to a full request queue, 294 // then send a retry at this point, also note that if the 295 // request we stalled was waiting for the response queue 296 // rather than the request queue we might stall it again 297 slavePort.retryStalledReq(); 298 } 299 300 // if the send failed, then we try again once we receive a retry, 301 // and therefore there is no need to take any action 302} 303 304void 305Bridge::BridgeSlavePort::trySendTiming() 306{ 307 assert(!transmitList.empty()); 308 309 DeferredPacket resp = transmitList.front(); 310 311 assert(resp.tick <= curTick()); 312 313 PacketPtr pkt = resp.pkt; 314 315 DPRINTF(Bridge, "trySend response addr 0x%x, outstanding %d\n", 316 pkt->getAddr(), outstandingResponses); 317 318 if (sendTimingResp(pkt)) { 319 // send successful 320 transmitList.pop_front(); 321 DPRINTF(Bridge, "trySend response successful\n"); 322 323 assert(outstandingResponses != 0); 324 --outstandingResponses; 325 326 // If there are more packets to send, schedule event to try again. 327 if (!transmitList.empty()) { 328 DeferredPacket next_resp = transmitList.front(); 329 DPRINTF(Bridge, "Scheduling next send\n"); 330 bridge.schedule(sendEvent, std::max(next_resp.tick, 331 bridge.clockEdge())); 332 } 333 334 // if there is space in the request queue and we were stalling 335 // a request, it will definitely be possible to accept it now 336 // since there is guaranteed space in the response queue 337 if (!masterPort.reqQueueFull() && retryReq) { 338 DPRINTF(Bridge, "Request waiting for retry, now retrying\n"); 339 retryReq = false; 340 sendRetry(); 341 } 342 } 343 344 // if the send failed, then we try again once we receive a retry, 345 // and therefore there is no need to take any action 346} 347 348void 349Bridge::BridgeMasterPort::recvRetry() 350{ 351 trySendTiming(); 352} 353 354void 355Bridge::BridgeSlavePort::recvRetry() 356{ 357 trySendTiming(); 358} 359 360Tick 361Bridge::BridgeSlavePort::recvAtomic(PacketPtr pkt) 362{ 363 return delay * bridge.clockPeriod() + masterPort.sendAtomic(pkt); 364} 365 366void 367Bridge::BridgeSlavePort::recvFunctional(PacketPtr pkt) 368{ 369 pkt->pushLabel(name()); 370 371 // check the response queue 372 for (auto i = transmitList.begin(); i != transmitList.end(); ++i) { 373 if (pkt->checkFunctional((*i).pkt)) { 374 pkt->makeResponse(); 375 return; 376 } 377 } 378 379 // also check the master port's request queue 380 if (masterPort.checkFunctional(pkt)) { 381 return; 382 } 383 384 pkt->popLabel(); 385 386 // fall through if pkt still not satisfied 387 masterPort.sendFunctional(pkt); 388} 389 390bool 391Bridge::BridgeMasterPort::checkFunctional(PacketPtr pkt) 392{ 393 bool found = false; 394 auto i = transmitList.begin(); 395 396 while(i != transmitList.end() && !found) { 397 if (pkt->checkFunctional((*i).pkt)) { 398 pkt->makeResponse(); 399 found = true; 400 } 401 ++i; 402 } 403 404 return found; 405} 406 407AddrRangeList 408Bridge::BridgeSlavePort::getAddrRanges() const 409{ 410 return ranges; 411} 412 413Bridge * 414BridgeParams::create() 415{ 416 return new Bridge(this); 417} 418