bridge.cc revision 12084:5a3769ff3d55
1/* 2 * Copyright (c) 2011-2013, 2015 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 bridge that connects a master 48 * and a slave through a request and response queue. 49 */ 50 51#include "mem/bridge.hh" 52 53#include "base/trace.hh" 54#include "debug/Bridge.hh" 55#include "params/Bridge.hh" 56 57Bridge::BridgeSlavePort::BridgeSlavePort(const std::string& _name, 58 Bridge& _bridge, 59 BridgeMasterPort& _masterPort, 60 Cycles _delay, int _resp_limit, 61 std::vector<AddrRange> _ranges) 62 : SlavePort(_name, &_bridge), bridge(_bridge), masterPort(_masterPort), 63 delay(_delay), ranges(_ranges.begin(), _ranges.end()), 64 outstandingResponses(0), retryReq(false), respQueueLimit(_resp_limit), 65 sendEvent([this]{ trySendTiming(); }, _name) 66{ 67} 68 69Bridge::BridgeMasterPort::BridgeMasterPort(const std::string& _name, 70 Bridge& _bridge, 71 BridgeSlavePort& _slavePort, 72 Cycles _delay, int _req_limit) 73 : MasterPort(_name, &_bridge), bridge(_bridge), slavePort(_slavePort), 74 delay(_delay), reqQueueLimit(_req_limit), 75 sendEvent([this]{ trySendTiming(); }, _name) 76{ 77} 78 79Bridge::Bridge(Params *p) 80 : MemObject(p), 81 slavePort(p->name + ".slave", *this, masterPort, 82 ticksToCycles(p->delay), p->resp_size, p->ranges), 83 masterPort(p->name + ".master", *this, slavePort, 84 ticksToCycles(p->delay), p->req_size) 85{ 86} 87 88BaseMasterPort& 89Bridge::getMasterPort(const std::string &if_name, PortID idx) 90{ 91 if (if_name == "master") 92 return masterPort; 93 else 94 // pass it along to our super class 95 return MemObject::getMasterPort(if_name, idx); 96} 97 98BaseSlavePort& 99Bridge::getSlavePort(const std::string &if_name, PortID idx) 100{ 101 if (if_name == "slave") 102 return slavePort; 103 else 104 // pass it along to our super class 105 return MemObject::getSlavePort(if_name, idx); 106} 107 108void 109Bridge::init() 110{ 111 // make sure both sides are connected and have the same block size 112 if (!slavePort.isConnected() || !masterPort.isConnected()) 113 fatal("Both ports of a bridge must be connected.\n"); 114 115 // notify the master side of our address ranges 116 slavePort.sendRangeChange(); 117} 118 119bool 120Bridge::BridgeSlavePort::respQueueFull() const 121{ 122 return outstandingResponses == respQueueLimit; 123} 124 125bool 126Bridge::BridgeMasterPort::reqQueueFull() const 127{ 128 return transmitList.size() == reqQueueLimit; 129} 130 131bool 132Bridge::BridgeMasterPort::recvTimingResp(PacketPtr pkt) 133{ 134 // all checks are done when the request is accepted on the slave 135 // side, so we are guaranteed to have space for the response 136 DPRINTF(Bridge, "recvTimingResp: %s addr 0x%x\n", 137 pkt->cmdString(), pkt->getAddr()); 138 139 DPRINTF(Bridge, "Request queue size: %d\n", transmitList.size()); 140 141 // technically the packet only reaches us after the header delay, 142 // and typically we also need to deserialise any payload (unless 143 // the two sides of the bridge are synchronous) 144 Tick receive_delay = pkt->headerDelay + pkt->payloadDelay; 145 pkt->headerDelay = pkt->payloadDelay = 0; 146 147 slavePort.schedTimingResp(pkt, bridge.clockEdge(delay) + 148 receive_delay); 149 150 return true; 151} 152 153bool 154Bridge::BridgeSlavePort::recvTimingReq(PacketPtr pkt) 155{ 156 DPRINTF(Bridge, "recvTimingReq: %s addr 0x%x\n", 157 pkt->cmdString(), pkt->getAddr()); 158 159 panic_if(pkt->cacheResponding(), "Should not see packets where cache " 160 "is responding"); 161 162 // we should not get a new request after committing to retry the 163 // current one, but unfortunately the CPU violates this rule, so 164 // simply ignore it for now 165 if (retryReq) 166 return false; 167 168 DPRINTF(Bridge, "Response queue size: %d outresp: %d\n", 169 transmitList.size(), outstandingResponses); 170 171 // if the request queue is full then there is no hope 172 if (masterPort.reqQueueFull()) { 173 DPRINTF(Bridge, "Request queue full\n"); 174 retryReq = true; 175 } else { 176 // look at the response queue if we expect to see a response 177 bool expects_response = pkt->needsResponse(); 178 if (expects_response) { 179 if (respQueueFull()) { 180 DPRINTF(Bridge, "Response queue full\n"); 181 retryReq = true; 182 } else { 183 // ok to send the request with space for the response 184 DPRINTF(Bridge, "Reserving space for response\n"); 185 assert(outstandingResponses != respQueueLimit); 186 ++outstandingResponses; 187 188 // no need to set retryReq to false as this is already the 189 // case 190 } 191 } 192 193 if (!retryReq) { 194 // technically the packet only reaches us after the header 195 // delay, and typically we also need to deserialise any 196 // payload (unless the two sides of the bridge are 197 // synchronous) 198 Tick receive_delay = pkt->headerDelay + pkt->payloadDelay; 199 pkt->headerDelay = pkt->payloadDelay = 0; 200 201 masterPort.schedTimingReq(pkt, bridge.clockEdge(delay) + 202 receive_delay); 203 } 204 } 205 206 // remember that we are now stalling a packet and that we have to 207 // tell the sending master to retry once space becomes available, 208 // we make no distinction whether the stalling is due to the 209 // request queue or response queue being full 210 return !retryReq; 211} 212 213void 214Bridge::BridgeSlavePort::retryStalledReq() 215{ 216 if (retryReq) { 217 DPRINTF(Bridge, "Request waiting for retry, now retrying\n"); 218 retryReq = false; 219 sendRetryReq(); 220 } 221} 222 223void 224Bridge::BridgeMasterPort::schedTimingReq(PacketPtr pkt, Tick when) 225{ 226 // If we're about to put this packet at the head of the queue, we 227 // need to schedule an event to do the transmit. Otherwise there 228 // should already be an event scheduled for sending the head 229 // packet. 230 if (transmitList.empty()) { 231 bridge.schedule(sendEvent, when); 232 } 233 234 assert(transmitList.size() != reqQueueLimit); 235 236 transmitList.emplace_back(pkt, when); 237} 238 239 240void 241Bridge::BridgeSlavePort::schedTimingResp(PacketPtr pkt, Tick when) 242{ 243 // If we're about to put this packet at the head of the queue, we 244 // need to schedule an event to do the transmit. Otherwise there 245 // should already be an event scheduled for sending the head 246 // packet. 247 if (transmitList.empty()) { 248 bridge.schedule(sendEvent, when); 249 } 250 251 transmitList.emplace_back(pkt, when); 252} 253 254void 255Bridge::BridgeMasterPort::trySendTiming() 256{ 257 assert(!transmitList.empty()); 258 259 DeferredPacket req = transmitList.front(); 260 261 assert(req.tick <= curTick()); 262 263 PacketPtr pkt = req.pkt; 264 265 DPRINTF(Bridge, "trySend request addr 0x%x, queue size %d\n", 266 pkt->getAddr(), transmitList.size()); 267 268 if (sendTimingReq(pkt)) { 269 // send successful 270 transmitList.pop_front(); 271 DPRINTF(Bridge, "trySend request successful\n"); 272 273 // If there are more packets to send, schedule event to try again. 274 if (!transmitList.empty()) { 275 DeferredPacket next_req = transmitList.front(); 276 DPRINTF(Bridge, "Scheduling next send\n"); 277 bridge.schedule(sendEvent, std::max(next_req.tick, 278 bridge.clockEdge())); 279 } 280 281 // if we have stalled a request due to a full request queue, 282 // then send a retry at this point, also note that if the 283 // request we stalled was waiting for the response queue 284 // rather than the request queue we might stall it again 285 slavePort.retryStalledReq(); 286 } 287 288 // if the send failed, then we try again once we receive a retry, 289 // and therefore there is no need to take any action 290} 291 292void 293Bridge::BridgeSlavePort::trySendTiming() 294{ 295 assert(!transmitList.empty()); 296 297 DeferredPacket resp = transmitList.front(); 298 299 assert(resp.tick <= curTick()); 300 301 PacketPtr pkt = resp.pkt; 302 303 DPRINTF(Bridge, "trySend response addr 0x%x, outstanding %d\n", 304 pkt->getAddr(), outstandingResponses); 305 306 if (sendTimingResp(pkt)) { 307 // send successful 308 transmitList.pop_front(); 309 DPRINTF(Bridge, "trySend response successful\n"); 310 311 assert(outstandingResponses != 0); 312 --outstandingResponses; 313 314 // If there are more packets to send, schedule event to try again. 315 if (!transmitList.empty()) { 316 DeferredPacket next_resp = transmitList.front(); 317 DPRINTF(Bridge, "Scheduling next send\n"); 318 bridge.schedule(sendEvent, std::max(next_resp.tick, 319 bridge.clockEdge())); 320 } 321 322 // if there is space in the request queue and we were stalling 323 // a request, it will definitely be possible to accept it now 324 // since there is guaranteed space in the response queue 325 if (!masterPort.reqQueueFull() && retryReq) { 326 DPRINTF(Bridge, "Request waiting for retry, now retrying\n"); 327 retryReq = false; 328 sendRetryReq(); 329 } 330 } 331 332 // if the send failed, then we try again once we receive a retry, 333 // and therefore there is no need to take any action 334} 335 336void 337Bridge::BridgeMasterPort::recvReqRetry() 338{ 339 trySendTiming(); 340} 341 342void 343Bridge::BridgeSlavePort::recvRespRetry() 344{ 345 trySendTiming(); 346} 347 348Tick 349Bridge::BridgeSlavePort::recvAtomic(PacketPtr pkt) 350{ 351 panic_if(pkt->cacheResponding(), "Should not see packets where cache " 352 "is responding"); 353 354 return delay * bridge.clockPeriod() + masterPort.sendAtomic(pkt); 355} 356 357void 358Bridge::BridgeSlavePort::recvFunctional(PacketPtr pkt) 359{ 360 pkt->pushLabel(name()); 361 362 // check the response queue 363 for (auto i = transmitList.begin(); i != transmitList.end(); ++i) { 364 if (pkt->checkFunctional((*i).pkt)) { 365 pkt->makeResponse(); 366 return; 367 } 368 } 369 370 // also check the master port's request queue 371 if (masterPort.checkFunctional(pkt)) { 372 return; 373 } 374 375 pkt->popLabel(); 376 377 // fall through if pkt still not satisfied 378 masterPort.sendFunctional(pkt); 379} 380 381bool 382Bridge::BridgeMasterPort::checkFunctional(PacketPtr pkt) 383{ 384 bool found = false; 385 auto i = transmitList.begin(); 386 387 while (i != transmitList.end() && !found) { 388 if (pkt->checkFunctional((*i).pkt)) { 389 pkt->makeResponse(); 390 found = true; 391 } 392 ++i; 393 } 394 395 return found; 396} 397 398AddrRangeList 399Bridge::BridgeSlavePort::getAddrRanges() const 400{ 401 return ranges; 402} 403 404Bridge * 405BridgeParams::create() 406{ 407 return new Bridge(this); 408} 409