bridge.cc revision 11193
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 "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 a bridge must be connected.\n"); 112 113 // notify the master side of our address ranges 114 slavePort.sendRangeChange(); 115} 116 117bool 118Bridge::BridgeSlavePort::respQueueFull() const 119{ 120 return outstandingResponses == respQueueLimit; 121} 122 123bool 124Bridge::BridgeMasterPort::reqQueueFull() const 125{ 126 return transmitList.size() == reqQueueLimit; 127} 128 129bool 130Bridge::BridgeMasterPort::recvTimingResp(PacketPtr pkt) 131{ 132 // all checks are done when the request is accepted on the slave 133 // side, so we are guaranteed to have space for the response 134 DPRINTF(Bridge, "recvTimingResp: %s addr 0x%x\n", 135 pkt->cmdString(), pkt->getAddr()); 136 137 DPRINTF(Bridge, "Request queue size: %d\n", transmitList.size()); 138 139 // technically the packet only reaches us after the header delay, 140 // and typically we also need to deserialise any payload (unless 141 // the two sides of the bridge are synchronous) 142 Tick receive_delay = pkt->headerDelay + pkt->payloadDelay; 143 pkt->headerDelay = pkt->payloadDelay = 0; 144 145 slavePort.schedTimingResp(pkt, bridge.clockEdge(delay) + 146 receive_delay); 147 148 return true; 149} 150 151bool 152Bridge::BridgeSlavePort::recvTimingReq(PacketPtr pkt) 153{ 154 DPRINTF(Bridge, "recvTimingReq: %s addr 0x%x\n", 155 pkt->cmdString(), pkt->getAddr()); 156 157 // sink inhibited packets without further action, also discard any 158 // packet that is not a read or a write 159 if (pkt->memInhibitAsserted() || 160 !(pkt->isWrite() || pkt->isRead())) { 161 assert(!pkt->needsResponse()); 162 pendingDelete.reset(pkt); 163 return true; 164 } 165 166 // we should not get a new request after committing to retry the 167 // current one, but unfortunately the CPU violates this rule, so 168 // simply ignore it for now 169 if (retryReq) 170 return false; 171 172 DPRINTF(Bridge, "Response queue size: %d outresp: %d\n", 173 transmitList.size(), outstandingResponses); 174 175 // if the request queue is full then there is no hope 176 if (masterPort.reqQueueFull()) { 177 DPRINTF(Bridge, "Request queue full\n"); 178 retryReq = true; 179 } else { 180 // look at the response queue if we expect to see a response 181 bool expects_response = pkt->needsResponse(); 182 if (expects_response) { 183 if (respQueueFull()) { 184 DPRINTF(Bridge, "Response queue full\n"); 185 retryReq = true; 186 } else { 187 // ok to send the request with space for the response 188 DPRINTF(Bridge, "Reserving space for response\n"); 189 assert(outstandingResponses != respQueueLimit); 190 ++outstandingResponses; 191 192 // no need to set retryReq to false as this is already the 193 // case 194 } 195 } 196 197 if (!retryReq) { 198 // technically the packet only reaches us after the header 199 // delay, and typically we also need to deserialise any 200 // payload (unless the two sides of the bridge are 201 // synchronous) 202 Tick receive_delay = pkt->headerDelay + pkt->payloadDelay; 203 pkt->headerDelay = pkt->payloadDelay = 0; 204 205 masterPort.schedTimingReq(pkt, bridge.clockEdge(delay) + 206 receive_delay); 207 } 208 } 209 210 // remember that we are now stalling a packet and that we have to 211 // tell the sending master to retry once space becomes available, 212 // we make no distinction whether the stalling is due to the 213 // request queue or response queue being full 214 return !retryReq; 215} 216 217void 218Bridge::BridgeSlavePort::retryStalledReq() 219{ 220 if (retryReq) { 221 DPRINTF(Bridge, "Request waiting for retry, now retrying\n"); 222 retryReq = false; 223 sendRetryReq(); 224 } 225} 226 227void 228Bridge::BridgeMasterPort::schedTimingReq(PacketPtr pkt, Tick when) 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 (transmitList.empty()) { 235 bridge.schedule(sendEvent, when); 236 } 237 238 assert(transmitList.size() != reqQueueLimit); 239 240 transmitList.emplace_back(pkt, when); 241} 242 243 244void 245Bridge::BridgeSlavePort::schedTimingResp(PacketPtr pkt, Tick when) 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 (transmitList.empty()) { 252 bridge.schedule(sendEvent, when); 253 } 254 255 transmitList.emplace_back(pkt, when); 256} 257 258void 259Bridge::BridgeMasterPort::trySendTiming() 260{ 261 assert(!transmitList.empty()); 262 263 DeferredPacket req = transmitList.front(); 264 265 assert(req.tick <= curTick()); 266 267 PacketPtr pkt = req.pkt; 268 269 DPRINTF(Bridge, "trySend request addr 0x%x, queue size %d\n", 270 pkt->getAddr(), transmitList.size()); 271 272 if (sendTimingReq(pkt)) { 273 // send successful 274 transmitList.pop_front(); 275 DPRINTF(Bridge, "trySend request successful\n"); 276 277 // If there are more packets to send, schedule event to try again. 278 if (!transmitList.empty()) { 279 DeferredPacket next_req = transmitList.front(); 280 DPRINTF(Bridge, "Scheduling next send\n"); 281 bridge.schedule(sendEvent, std::max(next_req.tick, 282 bridge.clockEdge())); 283 } 284 285 // if we have stalled a request due to a full request queue, 286 // then send a retry at this point, also note that if the 287 // request we stalled was waiting for the response queue 288 // rather than the request queue we might stall it again 289 slavePort.retryStalledReq(); 290 } 291 292 // if the send failed, then we try again once we receive a retry, 293 // and therefore there is no need to take any action 294} 295 296void 297Bridge::BridgeSlavePort::trySendTiming() 298{ 299 assert(!transmitList.empty()); 300 301 DeferredPacket resp = transmitList.front(); 302 303 assert(resp.tick <= curTick()); 304 305 PacketPtr pkt = resp.pkt; 306 307 DPRINTF(Bridge, "trySend response addr 0x%x, outstanding %d\n", 308 pkt->getAddr(), outstandingResponses); 309 310 if (sendTimingResp(pkt)) { 311 // send successful 312 transmitList.pop_front(); 313 DPRINTF(Bridge, "trySend response successful\n"); 314 315 assert(outstandingResponses != 0); 316 --outstandingResponses; 317 318 // If there are more packets to send, schedule event to try again. 319 if (!transmitList.empty()) { 320 DeferredPacket next_resp = transmitList.front(); 321 DPRINTF(Bridge, "Scheduling next send\n"); 322 bridge.schedule(sendEvent, std::max(next_resp.tick, 323 bridge.clockEdge())); 324 } 325 326 // if there is space in the request queue and we were stalling 327 // a request, it will definitely be possible to accept it now 328 // since there is guaranteed space in the response queue 329 if (!masterPort.reqQueueFull() && retryReq) { 330 DPRINTF(Bridge, "Request waiting for retry, now retrying\n"); 331 retryReq = false; 332 sendRetryReq(); 333 } 334 } 335 336 // if the send failed, then we try again once we receive a retry, 337 // and therefore there is no need to take any action 338} 339 340void 341Bridge::BridgeMasterPort::recvReqRetry() 342{ 343 trySendTiming(); 344} 345 346void 347Bridge::BridgeSlavePort::recvRespRetry() 348{ 349 trySendTiming(); 350} 351 352Tick 353Bridge::BridgeSlavePort::recvAtomic(PacketPtr pkt) 354{ 355 return delay * bridge.clockPeriod() + masterPort.sendAtomic(pkt); 356} 357 358void 359Bridge::BridgeSlavePort::recvFunctional(PacketPtr pkt) 360{ 361 pkt->pushLabel(name()); 362 363 // check the response queue 364 for (auto i = transmitList.begin(); i != transmitList.end(); ++i) { 365 if (pkt->checkFunctional((*i).pkt)) { 366 pkt->makeResponse(); 367 return; 368 } 369 } 370 371 // also check the master port's request queue 372 if (masterPort.checkFunctional(pkt)) { 373 return; 374 } 375 376 pkt->popLabel(); 377 378 // fall through if pkt still not satisfied 379 masterPort.sendFunctional(pkt); 380} 381 382bool 383Bridge::BridgeMasterPort::checkFunctional(PacketPtr pkt) 384{ 385 bool found = false; 386 auto i = transmitList.begin(); 387 388 while(i != transmitList.end() && !found) { 389 if (pkt->checkFunctional((*i).pkt)) { 390 pkt->makeResponse(); 391 found = true; 392 } 393 ++i; 394 } 395 396 return found; 397} 398 399AddrRangeList 400Bridge::BridgeSlavePort::getAddrRanges() const 401{ 402 return ranges; 403} 404 405Bridge * 406BridgeParams::create() 407{ 408 return new Bridge(this); 409} 410