bridge.cc revision 9549
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/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() 124{ 125 return outstandingResponses == respQueueLimit; 126} 127 128bool 129Bridge::BridgeMasterPort::reqQueueFull() 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 // ensure we do not have something waiting to retry 159 if(retryReq) 160 return false; 161 162 DPRINTF(Bridge, "Response queue size: %d outresp: %d\n", 163 transmitList.size(), outstandingResponses); 164 165 if (masterPort.reqQueueFull()) { 166 DPRINTF(Bridge, "Request queue full\n"); 167 retryReq = true; 168 } else if (pkt->needsResponse()) { 169 if (respQueueFull()) { 170 DPRINTF(Bridge, "Response queue full\n"); 171 retryReq = true; 172 } else { 173 DPRINTF(Bridge, "Reserving space for response\n"); 174 assert(outstandingResponses != respQueueLimit); 175 ++outstandingResponses; 176 retryReq = false; 177 178 // @todo: We need to pay for this and not just zero it out 179 pkt->busFirstWordDelay = pkt->busLastWordDelay = 0; 180 181 masterPort.schedTimingReq(pkt, bridge.clockEdge(delay)); 182 } 183 } 184 185 // remember that we are now stalling a packet and that we have to 186 // tell the sending master to retry once space becomes available, 187 // we make no distinction whether the stalling is due to the 188 // request queue or response queue being full 189 return !retryReq; 190} 191 192void 193Bridge::BridgeSlavePort::retryStalledReq() 194{ 195 if (retryReq) { 196 DPRINTF(Bridge, "Request waiting for retry, now retrying\n"); 197 retryReq = false; 198 sendRetry(); 199 } 200} 201 202void 203Bridge::BridgeMasterPort::schedTimingReq(PacketPtr pkt, Tick when) 204{ 205 // If we expect to see a response, we need to restore the source 206 // and destination field that is potentially changed by a second 207 // bus 208 if (!pkt->memInhibitAsserted() && pkt->needsResponse()) { 209 // Update the sender state so we can deal with the response 210 // appropriately 211 pkt->pushSenderState(new RequestState(pkt->getSrc())); 212 } 213 214 // If we're about to put this packet at the head of the queue, we 215 // need to schedule an event to do the transmit. Otherwise there 216 // should already be an event scheduled for sending the head 217 // packet. 218 if (transmitList.empty()) { 219 bridge.schedule(sendEvent, when); 220 } 221 222 assert(transmitList.size() != reqQueueLimit); 223 224 transmitList.push_back(DeferredPacket(pkt, when)); 225} 226 227 228void 229Bridge::BridgeSlavePort::schedTimingResp(PacketPtr pkt, Tick when) 230{ 231 // This is a response for a request we forwarded earlier. The 232 // corresponding request state should be stored in the packet's 233 // senderState field. 234 RequestState *req_state = 235 dynamic_cast<RequestState*>(pkt->popSenderState()); 236 assert(req_state != NULL); 237 pkt->setDest(req_state->origSrc); 238 delete req_state; 239 240 // the bridge assumes that at least one bus has set the 241 // destination field of the packet 242 assert(pkt->isDestValid()); 243 DPRINTF(Bridge, "response, new dest %d\n", pkt->getDest()); 244 245 // If we're about to put this packet at the head of the queue, we 246 // need to schedule an event to do the transmit. Otherwise there 247 // should already be an event scheduled for sending the head 248 // packet. 249 if (transmitList.empty()) { 250 bridge.schedule(sendEvent, when); 251 } 252 253 transmitList.push_back(DeferredPacket(pkt, when)); 254} 255 256void 257Bridge::BridgeMasterPort::trySendTiming() 258{ 259 assert(!transmitList.empty()); 260 261 DeferredPacket req = transmitList.front(); 262 263 assert(req.tick <= curTick()); 264 265 PacketPtr pkt = req.pkt; 266 267 DPRINTF(Bridge, "trySend request addr 0x%x, queue size %d\n", 268 pkt->getAddr(), transmitList.size()); 269 270 if (sendTimingReq(pkt)) { 271 // send successful 272 transmitList.pop_front(); 273 DPRINTF(Bridge, "trySend request successful\n"); 274 275 // If there are more packets to send, schedule event to try again. 276 if (!transmitList.empty()) { 277 req = transmitList.front(); 278 DPRINTF(Bridge, "Scheduling next send\n"); 279 bridge.schedule(sendEvent, std::max(req.tick, 280 bridge.nextCycle())); 281 } 282 283 // if we have stalled a request due to a full request queue, 284 // then send a retry at this point, also note that if the 285 // request we stalled was waiting for the response queue 286 // rather than the request queue we might stall it again 287 slavePort.retryStalledReq(); 288 } 289 290 // if the send failed, then we try again once we receive a retry, 291 // and therefore there is no need to take any action 292} 293 294void 295Bridge::BridgeSlavePort::trySendTiming() 296{ 297 assert(!transmitList.empty()); 298 299 DeferredPacket resp = transmitList.front(); 300 301 assert(resp.tick <= curTick()); 302 303 PacketPtr pkt = resp.pkt; 304 305 DPRINTF(Bridge, "trySend response addr 0x%x, outstanding %d\n", 306 pkt->getAddr(), outstandingResponses); 307 308 if (sendTimingResp(pkt)) { 309 // send successful 310 transmitList.pop_front(); 311 DPRINTF(Bridge, "trySend response successful\n"); 312 313 assert(outstandingResponses != 0); 314 --outstandingResponses; 315 316 // If there are more packets to send, schedule event to try again. 317 if (!transmitList.empty()) { 318 resp = transmitList.front(); 319 DPRINTF(Bridge, "Scheduling next send\n"); 320 bridge.schedule(sendEvent, std::max(resp.tick, 321 bridge.nextCycle())); 322 } 323 324 // if there is space in the request queue and we were stalling 325 // a request, it will definitely be possible to accept it now 326 // since there is guaranteed space in the response queue 327 if (!masterPort.reqQueueFull() && retryReq) { 328 DPRINTF(Bridge, "Request waiting for retry, now retrying\n"); 329 retryReq = false; 330 sendRetry(); 331 } 332 } 333 334 // if the send failed, then we try again once we receive a retry, 335 // and therefore there is no need to take any action 336} 337 338void 339Bridge::BridgeMasterPort::recvRetry() 340{ 341 Tick nextReady = transmitList.front().tick; 342 if (nextReady <= curTick()) 343 trySendTiming(); 344 else 345 bridge.schedule(sendEvent, nextReady); 346} 347 348void 349Bridge::BridgeSlavePort::recvRetry() 350{ 351 Tick nextReady = transmitList.front().tick; 352 if (nextReady <= curTick()) 353 trySendTiming(); 354 else 355 bridge.schedule(sendEvent, nextReady); 356} 357 358Tick 359Bridge::BridgeSlavePort::recvAtomic(PacketPtr pkt) 360{ 361 return delay * bridge.clockPeriod() + masterPort.sendAtomic(pkt); 362} 363 364void 365Bridge::BridgeSlavePort::recvFunctional(PacketPtr pkt) 366{ 367 std::list<DeferredPacket>::iterator i; 368 369 pkt->pushLabel(name()); 370 371 // check the response queue 372 for (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 std::list<DeferredPacket>::iterator 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