bridge.cc revision 9164
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 int _delay, int _resp_limit, 60 std::vector<Range<Addr> > _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 int _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, p->delay, p->resp_size, 80 p->ranges), 81 masterPort(p->name + ".master", *this, slavePort, p->delay, p->req_size) 82{ 83} 84 85MasterPort& 86Bridge::getMasterPort(const std::string &if_name, int idx) 87{ 88 if (if_name == "master") 89 return masterPort; 90 else 91 // pass it along to our super class 92 return MemObject::getMasterPort(if_name, idx); 93} 94 95SlavePort& 96Bridge::getSlavePort(const std::string &if_name, int idx) 97{ 98 if (if_name == "slave") 99 return slavePort; 100 else 101 // pass it along to our super class 102 return MemObject::getSlavePort(if_name, idx); 103} 104 105void 106Bridge::init() 107{ 108 // make sure both sides are connected and have the same block size 109 if (!slavePort.isConnected() || !masterPort.isConnected()) 110 fatal("Both ports of bus bridge are not connected to a bus.\n"); 111 112 if (slavePort.peerBlockSize() != masterPort.peerBlockSize()) 113 fatal("Slave port size %d, master port size %d \n " \ 114 "Busses don't have the same block size... Not supported.\n", 115 slavePort.peerBlockSize(), masterPort.peerBlockSize()); 116 117 // notify the master side of our address ranges 118 slavePort.sendRangeChange(); 119} 120 121bool 122Bridge::BridgeSlavePort::respQueueFull() 123{ 124 return outstandingResponses == respQueueLimit; 125} 126 127bool 128Bridge::BridgeMasterPort::reqQueueFull() 129{ 130 return transmitList.size() == reqQueueLimit; 131} 132 133bool 134Bridge::BridgeMasterPort::recvTimingResp(PacketPtr pkt) 135{ 136 // all checks are done when the request is accepted on the slave 137 // side, so we are guaranteed to have space for the response 138 DPRINTF(Bridge, "recvTimingResp: %s addr 0x%x\n", 139 pkt->cmdString(), pkt->getAddr()); 140 141 DPRINTF(Bridge, "Request queue size: %d\n", transmitList.size()); 142 143 slavePort.schedTimingResp(pkt, curTick() + delay); 144 145 return true; 146} 147 148bool 149Bridge::BridgeSlavePort::recvTimingReq(PacketPtr pkt) 150{ 151 DPRINTF(Bridge, "recvTimingReq: %s addr 0x%x\n", 152 pkt->cmdString(), pkt->getAddr()); 153 154 // ensure we do not have something waiting to retry 155 if(retryReq) 156 return false; 157 158 DPRINTF(Bridge, "Response queue size: %d outresp: %d\n", 159 transmitList.size(), outstandingResponses); 160 161 if (masterPort.reqQueueFull()) { 162 DPRINTF(Bridge, "Request queue full\n"); 163 retryReq = true; 164 } else if (pkt->needsResponse()) { 165 if (respQueueFull()) { 166 DPRINTF(Bridge, "Response queue full\n"); 167 retryReq = true; 168 } else { 169 DPRINTF(Bridge, "Reserving space for response\n"); 170 assert(outstandingResponses != respQueueLimit); 171 ++outstandingResponses; 172 retryReq = false; 173 masterPort.schedTimingReq(pkt, curTick() + delay); 174 } 175 } 176 177 // remember that we are now stalling a packet and that we have to 178 // tell the sending master to retry once space becomes available, 179 // we make no distinction whether the stalling is due to the 180 // request queue or response queue being full 181 return !retryReq; 182} 183 184void 185Bridge::BridgeSlavePort::retryStalledReq() 186{ 187 if (retryReq) { 188 DPRINTF(Bridge, "Request waiting for retry, now retrying\n"); 189 retryReq = false; 190 sendRetry(); 191 } 192} 193 194void 195Bridge::BridgeMasterPort::schedTimingReq(PacketPtr pkt, Tick when) 196{ 197 // If we expect to see a response, we need to restore the source 198 // and destination field that is potentially changed by a second 199 // bus 200 if (!pkt->memInhibitAsserted() && pkt->needsResponse()) { 201 // Update the sender state so we can deal with the response 202 // appropriately 203 RequestState *req_state = new RequestState(pkt); 204 pkt->senderState = req_state; 205 } 206 207 // If we're about to put this packet at the head of the queue, we 208 // need to schedule an event to do the transmit. Otherwise there 209 // should already be an event scheduled for sending the head 210 // packet. 211 if (transmitList.empty()) { 212 bridge.schedule(sendEvent, when); 213 } 214 215 assert(transmitList.size() != reqQueueLimit); 216 217 transmitList.push_back(DeferredPacket(pkt, when)); 218} 219 220 221void 222Bridge::BridgeSlavePort::schedTimingResp(PacketPtr pkt, Tick when) 223{ 224 // This is a response for a request we forwarded earlier. The 225 // corresponding request state should be stored in the packet's 226 // senderState field. 227 RequestState *req_state = dynamic_cast<RequestState*>(pkt->senderState); 228 assert(req_state != NULL); 229 // set up new packet dest & senderState based on values saved 230 // from original request 231 req_state->fixResponse(pkt); 232 delete req_state; 233 234 // the bridge assumes that at least one bus has set the 235 // destination field of the packet 236 assert(pkt->isDestValid()); 237 DPRINTF(Bridge, "response, new dest %d\n", pkt->getDest()); 238 239 // If we're about to put this packet at the head of the queue, we 240 // need to schedule an event to do the transmit. Otherwise there 241 // should already be an event scheduled for sending the head 242 // packet. 243 if (transmitList.empty()) { 244 bridge.schedule(sendEvent, when); 245 } 246 247 transmitList.push_back(DeferredPacket(pkt, when)); 248} 249 250void 251Bridge::BridgeMasterPort::trySendTiming() 252{ 253 assert(!transmitList.empty()); 254 255 DeferredPacket req = transmitList.front(); 256 257 assert(req.tick <= curTick()); 258 259 PacketPtr pkt = req.pkt; 260 261 DPRINTF(Bridge, "trySend request addr 0x%x, queue size %d\n", 262 pkt->getAddr(), transmitList.size()); 263 264 if (sendTimingReq(pkt)) { 265 // send successful 266 transmitList.pop_front(); 267 DPRINTF(Bridge, "trySend request successful\n"); 268 269 // If there are more packets to send, schedule event to try again. 270 if (!transmitList.empty()) { 271 req = transmitList.front(); 272 DPRINTF(Bridge, "Scheduling next send\n"); 273 bridge.schedule(sendEvent, std::max(req.tick, 274 bridge.nextCycle())); 275 } 276 277 // if we have stalled a request due to a full request queue, 278 // then send a retry at this point, also note that if the 279 // request we stalled was waiting for the response queue 280 // rather than the request queue we might stall it again 281 slavePort.retryStalledReq(); 282 } 283 284 // if the send failed, then we try again once we receive a retry, 285 // and therefore there is no need to take any action 286} 287 288void 289Bridge::BridgeSlavePort::trySendTiming() 290{ 291 assert(!transmitList.empty()); 292 293 DeferredPacket resp = transmitList.front(); 294 295 assert(resp.tick <= curTick()); 296 297 PacketPtr pkt = resp.pkt; 298 299 DPRINTF(Bridge, "trySend response addr 0x%x, outstanding %d\n", 300 pkt->getAddr(), outstandingResponses); 301 302 if (sendTimingResp(pkt)) { 303 // send successful 304 transmitList.pop_front(); 305 DPRINTF(Bridge, "trySend response successful\n"); 306 307 assert(outstandingResponses != 0); 308 --outstandingResponses; 309 310 // If there are more packets to send, schedule event to try again. 311 if (!transmitList.empty()) { 312 resp = transmitList.front(); 313 DPRINTF(Bridge, "Scheduling next send\n"); 314 bridge.schedule(sendEvent, std::max(resp.tick, 315 bridge.nextCycle())); 316 } 317 318 // if there is space in the request queue and we were stalling 319 // a request, it will definitely be possible to accept it now 320 // since there is guaranteed space in the response queue 321 if (!masterPort.reqQueueFull() && retryReq) { 322 DPRINTF(Bridge, "Request waiting for retry, now retrying\n"); 323 retryReq = false; 324 sendRetry(); 325 } 326 } 327 328 // if the send failed, then we try again once we receive a retry, 329 // and therefore there is no need to take any action 330} 331 332void 333Bridge::BridgeMasterPort::recvRetry() 334{ 335 Tick nextReady = transmitList.front().tick; 336 if (nextReady <= curTick()) 337 trySendTiming(); 338 else 339 bridge.schedule(sendEvent, nextReady); 340} 341 342void 343Bridge::BridgeSlavePort::recvRetry() 344{ 345 Tick nextReady = transmitList.front().tick; 346 if (nextReady <= curTick()) 347 trySendTiming(); 348 else 349 bridge.schedule(sendEvent, nextReady); 350} 351 352Tick 353Bridge::BridgeSlavePort::recvAtomic(PacketPtr pkt) 354{ 355 return delay + masterPort.sendAtomic(pkt); 356} 357 358void 359Bridge::BridgeSlavePort::recvFunctional(PacketPtr pkt) 360{ 361 std::list<DeferredPacket>::iterator i; 362 363 pkt->pushLabel(name()); 364 365 // check the response queue 366 for (i = transmitList.begin(); i != transmitList.end(); ++i) { 367 if (pkt->checkFunctional((*i).pkt)) { 368 pkt->makeResponse(); 369 return; 370 } 371 } 372 373 // also check the master port's request queue 374 if (masterPort.checkFunctional(pkt)) { 375 return; 376 } 377 378 pkt->popLabel(); 379 380 // fall through if pkt still not satisfied 381 masterPort.sendFunctional(pkt); 382} 383 384bool 385Bridge::BridgeMasterPort::checkFunctional(PacketPtr pkt) 386{ 387 bool found = false; 388 std::list<DeferredPacket>::iterator i = transmitList.begin(); 389 390 while(i != transmitList.end() && !found) { 391 if (pkt->checkFunctional((*i).pkt)) { 392 pkt->makeResponse(); 393 found = true; 394 } 395 ++i; 396 } 397 398 return found; 399} 400 401AddrRangeList 402Bridge::BridgeSlavePort::getAddrRanges() const 403{ 404 return ranges; 405} 406 407Bridge * 408BridgeParams::create() 409{ 410 return new Bridge(this); 411} 412