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 // 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 // @todo: We need to pay for this and not just zero it out 140 pkt->busFirstWordDelay = pkt->busLastWordDelay = 0; 141 142 slavePort.schedTimingResp(pkt, bridge.clockEdge(delay)); 143 144 return true; 145} 146 147bool 148Bridge::BridgeSlavePort::recvTimingReq(PacketPtr pkt) 149{ 150 DPRINTF(Bridge, "recvTimingReq: %s addr 0x%x\n", 151 pkt->cmdString(), pkt->getAddr()); 152 153 // we should not see a timing request if we are already in a retry 154 assert(!retryReq); 155 156 DPRINTF(Bridge, "Response queue size: %d outresp: %d\n", 157 transmitList.size(), outstandingResponses); 158 159 // if the request queue is full then there is no hope 160 if (masterPort.reqQueueFull()) { 161 DPRINTF(Bridge, "Request queue full\n"); 162 retryReq = true; 163 } else { 164 // look at the response queue if we expect to see a response 165 bool expects_response = pkt->needsResponse() && 166 !pkt->memInhibitAsserted(); 167 if (expects_response) { 168 if (respQueueFull()) { 169 DPRINTF(Bridge, "Response queue full\n"); 170 retryReq = true; 171 } else { 172 // ok to send the request with space for the response 173 DPRINTF(Bridge, "Reserving space for response\n"); 174 assert(outstandingResponses != respQueueLimit); 175 ++outstandingResponses; 176 177 // no need to set retryReq to false as this is already the 178 // case 179 } 180 } 181 182 if (!retryReq) { 183 // @todo: We need to pay for this and not just zero it out 184 pkt->busFirstWordDelay = pkt->busLastWordDelay = 0; 185 186 masterPort.schedTimingReq(pkt, bridge.clockEdge(delay)); 187 } 188 } 189 190 // remember that we are now stalling a packet and that we have to 191 // tell the sending master to retry once space becomes available, 192 // we make no distinction whether the stalling is due to the 193 // request queue or response queue being full 194 return !retryReq; 195} 196 197void 198Bridge::BridgeSlavePort::retryStalledReq() 199{ 200 if (retryReq) { 201 DPRINTF(Bridge, "Request waiting for retry, now retrying\n"); 202 retryReq = false; 203 sendRetry(); 204 } 205} 206 207void 208Bridge::BridgeMasterPort::schedTimingReq(PacketPtr pkt, Tick when) 209{ 210 // If we expect to see a response, we need to restore the source 211 // and destination field that is potentially changed by a second 212 // bus 213 if (!pkt->memInhibitAsserted() && pkt->needsResponse()) { 214 // Update the sender state so we can deal with the response 215 // appropriately 216 pkt->pushSenderState(new RequestState(pkt->getSrc())); 217 } 218 219 // If we're about to put this packet at the head of the queue, we 220 // need to schedule an event to do the transmit. Otherwise there 221 // should already be an event scheduled for sending the head 222 // packet. 223 if (transmitList.empty()) { 224 bridge.schedule(sendEvent, when); 225 } 226 227 assert(transmitList.size() != reqQueueLimit); 228 229 transmitList.push_back(DeferredPacket(pkt, when)); 230} 231 232 233void 234Bridge::BridgeSlavePort::schedTimingResp(PacketPtr pkt, Tick when) 235{ 236 // This is a response for a request we forwarded earlier. The 237 // corresponding request state should be stored in the packet's 238 // senderState field. 239 RequestState *req_state = 240 dynamic_cast<RequestState*>(pkt->popSenderState()); 241 assert(req_state != NULL); 242 pkt->setDest(req_state->origSrc); 243 delete req_state; 244 245 // the bridge assumes that at least one bus has set the 246 // destination field of the packet 247 assert(pkt->isDestValid()); 248 DPRINTF(Bridge, "response, new dest %d\n", pkt->getDest()); 249 250 // If we're about to put this packet at the head of the queue, we 251 // need to schedule an event to do the transmit. Otherwise there 252 // should already be an event scheduled for sending the head 253 // packet. 254 if (transmitList.empty()) { 255 bridge.schedule(sendEvent, when); 256 } 257 258 transmitList.push_back(DeferredPacket(pkt, when)); 259} 260 261void 262Bridge::BridgeMasterPort::trySendTiming() 263{ 264 assert(!transmitList.empty()); 265 266 DeferredPacket req = transmitList.front(); 267 268 assert(req.tick <= curTick()); 269 270 PacketPtr pkt = req.pkt; 271 272 DPRINTF(Bridge, "trySend request addr 0x%x, queue size %d\n", 273 pkt->getAddr(), transmitList.size()); 274 275 if (sendTimingReq(pkt)) { 276 // send successful 277 transmitList.pop_front(); 278 DPRINTF(Bridge, "trySend request successful\n"); 279 280 // If there are more packets to send, schedule event to try again. 281 if (!transmitList.empty()) { 282 DeferredPacket next_req = transmitList.front(); 283 DPRINTF(Bridge, "Scheduling next send\n"); 284 bridge.schedule(sendEvent, std::max(next_req.tick, 285 bridge.clockEdge())); 286 } 287 288 // if we have stalled a request due to a full request queue, 289 // then send a retry at this point, also note that if the 290 // request we stalled was waiting for the response queue 291 // rather than the request queue we might stall it again 292 slavePort.retryStalledReq(); 293 } 294 295 // if the send failed, then we try again once we receive a retry, 296 // and therefore there is no need to take any action 297} 298 299void 300Bridge::BridgeSlavePort::trySendTiming() 301{ 302 assert(!transmitList.empty()); 303 304 DeferredPacket resp = transmitList.front(); 305 306 assert(resp.tick <= curTick()); 307 308 PacketPtr pkt = resp.pkt; 309 310 DPRINTF(Bridge, "trySend response addr 0x%x, outstanding %d\n", 311 pkt->getAddr(), outstandingResponses); 312 313 if (sendTimingResp(pkt)) { 314 // send successful 315 transmitList.pop_front(); 316 DPRINTF(Bridge, "trySend response successful\n"); 317 318 assert(outstandingResponses != 0); 319 --outstandingResponses; 320 321 // If there are more packets to send, schedule event to try again. 322 if (!transmitList.empty()) { 323 DeferredPacket next_resp = transmitList.front(); 324 DPRINTF(Bridge, "Scheduling next send\n"); 325 bridge.schedule(sendEvent, std::max(next_resp.tick, 326 bridge.clockEdge())); 327 } 328 329 // if there is space in the request queue and we were stalling 330 // a request, it will definitely be possible to accept it now 331 // since there is guaranteed space in the response queue 332 if (!masterPort.reqQueueFull() && retryReq) { 333 DPRINTF(Bridge, "Request waiting for retry, now retrying\n"); 334 retryReq = false; 335 sendRetry(); 336 } 337 } 338 339 // if the send failed, then we try again once we receive a retry, 340 // and therefore there is no need to take any action 341} 342 343void 344Bridge::BridgeMasterPort::recvRetry() 345{ 346 trySendTiming(); 347} 348 349void 350Bridge::BridgeSlavePort::recvRetry() 351{ 352 trySendTiming(); 353} 354 355Tick 356Bridge::BridgeSlavePort::recvAtomic(PacketPtr pkt) 357{ 358 return delay * bridge.clockPeriod() + masterPort.sendAtomic(pkt); 359} 360 361void 362Bridge::BridgeSlavePort::recvFunctional(PacketPtr pkt) 363{ 364 pkt->pushLabel(name()); 365 366 // check the response queue 367 for (auto i = transmitList.begin(); i != transmitList.end(); ++i) { 368 if (pkt->checkFunctional((*i).pkt)) { 369 pkt->makeResponse(); 370 return; 371 } 372 } 373 374 // also check the master port's request queue 375 if (masterPort.checkFunctional(pkt)) { 376 return; 377 } 378 379 pkt->popLabel(); 380 381 // fall through if pkt still not satisfied 382 masterPort.sendFunctional(pkt); 383} 384 385bool 386Bridge::BridgeMasterPort::checkFunctional(PacketPtr pkt) 387{ 388 bool found = false; 389 auto i = transmitList.begin(); 390 391 while(i != transmitList.end() && !found) { 392 if (pkt->checkFunctional((*i).pkt)) { 393 pkt->makeResponse(); 394 found = true; 395 } 396 ++i; 397 } 398 399 return found; 400} 401 402AddrRangeList 403Bridge::BridgeSlavePort::getAddrRanges() const 404{ 405 return ranges; 406} 407 408Bridge * 409BridgeParams::create() 410{ 411 return new Bridge(this); 412} |