coherent_xbar.cc revision 9088
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 * Andreas Hansson 42 * William Wang 43 */ 44 45/** 46 * @file 47 * Definition of a bus object. 48 */ 49 50#include "base/misc.hh" 51#include "base/trace.hh" 52#include "debug/BusAddrRanges.hh" 53#include "debug/CoherentBus.hh" 54#include "mem/coherent_bus.hh" 55 56CoherentBus::CoherentBus(const CoherentBusParams *p) 57 : BaseBus(p) 58{ 59 // create the ports based on the size of the master and slave 60 // vector ports, and the presence of the default port, the ports 61 // are enumerated starting from zero 62 for (int i = 0; i < p->port_master_connection_count; ++i) { 63 std::string portName = csprintf("%s-p%d", name(), i); 64 MasterPort* bp = new CoherentBusMasterPort(portName, *this, i); 65 masterPorts.push_back(bp); 66 } 67 68 // see if we have a default slave device connected and if so add 69 // our corresponding master port 70 if (p->port_default_connection_count) { 71 defaultPortID = masterPorts.size(); 72 std::string portName = csprintf("%s-default", name()); 73 MasterPort* bp = new CoherentBusMasterPort(portName, *this, 74 defaultPortID); 75 masterPorts.push_back(bp); 76 } 77 78 // create the slave ports, once again starting at zero 79 for (int i = 0; i < p->port_slave_connection_count; ++i) { 80 std::string portName = csprintf("%s-p%d", name(), i); 81 SlavePort* bp = new CoherentBusSlavePort(portName, *this, i); 82 slavePorts.push_back(bp); 83 } 84 85 clearPortCache(); 86} 87 88void 89CoherentBus::init() 90{ 91 // iterate over our slave ports and determine which of our 92 // neighbouring master ports are snooping and add them as snoopers 93 for (SlavePortConstIter p = slavePorts.begin(); p != slavePorts.end(); 94 ++p) { 95 // check if the connected master port is snooping 96 if ((*p)->isSnooping()) { 97 DPRINTF(BusAddrRanges, "Adding snooping master %s\n", 98 (*p)->getMasterPort().name()); 99 snoopPorts.push_back(*p); 100 } 101 } 102 103 if (snoopPorts.empty()) 104 warn("CoherentBus %s has no snooping ports attached!\n", name()); 105} 106 107bool 108CoherentBus::recvTimingReq(PacketPtr pkt, PortID slave_port_id) 109{ 110 // determine the source port based on the id 111 SlavePort *src_port = slavePorts[slave_port_id]; 112 113 // test if the bus should be considered occupied for the current 114 // port, and exclude express snoops from the check 115 if (!pkt->isExpressSnoop() && isOccupied(src_port)) { 116 DPRINTF(CoherentBus, "recvTimingReq: src %s %s 0x%x BUSY\n", 117 src_port->name(), pkt->cmdString(), pkt->getAddr()); 118 return false; 119 } 120 121 DPRINTF(CoherentBus, "recvTimingReq: src %s %s 0x%x\n", 122 src_port->name(), pkt->cmdString(), pkt->getAddr()); 123 124 // set the source port for routing of the response 125 pkt->setSrc(slave_port_id); 126 127 Tick headerFinishTime = pkt->isExpressSnoop() ? 0 : calcPacketTiming(pkt); 128 Tick packetFinishTime = pkt->isExpressSnoop() ? 0 : pkt->finishTime; 129 130 // uncacheable requests need never be snooped 131 if (!pkt->req->isUncacheable()) { 132 // the packet is a memory-mapped request and should be 133 // broadcasted to our snoopers but the source 134 forwardTiming(pkt, slave_port_id); 135 } 136 137 // remember if we add an outstanding req so we can undo it if 138 // necessary, if the packet needs a response, we should add it 139 // as outstanding and express snoops never fail so there is 140 // not need to worry about them 141 bool add_outstanding = !pkt->isExpressSnoop() && pkt->needsResponse(); 142 143 // keep track that we have an outstanding request packet 144 // matching this request, this is used by the coherency 145 // mechanism in determining what to do with snoop responses 146 // (in recvTimingSnoop) 147 if (add_outstanding) { 148 // we should never have an exsiting request outstanding 149 assert(outstandingReq.find(pkt->req) == outstandingReq.end()); 150 outstandingReq.insert(pkt->req); 151 } 152 153 // since it is a normal request, determine the destination 154 // based on the address and attempt to send the packet 155 bool success = masterPorts[findPort(pkt->getAddr())]->sendTimingReq(pkt); 156 157 if (!success) { 158 // inhibited packets should never be forced to retry 159 assert(!pkt->memInhibitAsserted()); 160 161 // if it was added as outstanding and the send failed, then 162 // erase it again 163 if (add_outstanding) 164 outstandingReq.erase(pkt->req); 165 166 DPRINTF(CoherentBus, "recvTimingReq: src %s %s 0x%x RETRY\n", 167 src_port->name(), pkt->cmdString(), pkt->getAddr()); 168 169 addToRetryList(src_port); 170 occupyBus(headerFinishTime); 171 172 return false; 173 } 174 175 succeededTiming(packetFinishTime); 176 177 return true; 178} 179 180bool 181CoherentBus::recvTimingResp(PacketPtr pkt, PortID master_port_id) 182{ 183 // determine the source port based on the id 184 MasterPort *src_port = masterPorts[master_port_id]; 185 186 // test if the bus should be considered occupied for the current 187 // port 188 if (isOccupied(src_port)) { 189 DPRINTF(CoherentBus, "recvTimingResp: src %s %s 0x%x BUSY\n", 190 src_port->name(), pkt->cmdString(), pkt->getAddr()); 191 return false; 192 } 193 194 DPRINTF(CoherentBus, "recvTimingResp: src %s %s 0x%x\n", 195 src_port->name(), pkt->cmdString(), pkt->getAddr()); 196 197 calcPacketTiming(pkt); 198 Tick packetFinishTime = pkt->finishTime; 199 200 // the packet is a normal response to a request that we should 201 // have seen passing through the bus 202 assert(outstandingReq.find(pkt->req) != outstandingReq.end()); 203 204 // remove it as outstanding 205 outstandingReq.erase(pkt->req); 206 207 // send the packet to the destination through one of our slave 208 // ports, as determined by the destination field 209 bool success M5_VAR_USED = slavePorts[pkt->getDest()]->sendTimingResp(pkt); 210 211 // currently it is illegal to block responses... can lead to 212 // deadlock 213 assert(success); 214 215 succeededTiming(packetFinishTime); 216 217 return true; 218} 219 220void 221CoherentBus::recvTimingSnoopReq(PacketPtr pkt, PortID master_port_id) 222{ 223 DPRINTF(CoherentBus, "recvTimingSnoopReq: src %s %s 0x%x\n", 224 masterPorts[master_port_id]->name(), pkt->cmdString(), 225 pkt->getAddr()); 226 227 // we should only see express snoops from caches 228 assert(pkt->isExpressSnoop()); 229 230 // set the source port for routing of the response 231 pkt->setSrc(master_port_id); 232 233 // forward to all snoopers 234 forwardTiming(pkt, InvalidPortID); 235 236 // a snoop request came from a connected slave device (one of 237 // our master ports), and if it is not coming from the slave 238 // device responsible for the address range something is 239 // wrong, hence there is nothing further to do as the packet 240 // would be going back to where it came from 241 assert(master_port_id == findPort(pkt->getAddr())); 242 243 // this is an express snoop and is never forced to retry 244 assert(!inRetry); 245} 246 247bool 248CoherentBus::recvTimingSnoopResp(PacketPtr pkt, PortID slave_port_id) 249{ 250 // determine the source port based on the id 251 SlavePort* src_port = slavePorts[slave_port_id]; 252 253 // test if the bus should be considered occupied for the current 254 // port 255 if (isOccupied(src_port)) { 256 DPRINTF(CoherentBus, "recvTimingSnoopResp: src %s %s 0x%x BUSY\n", 257 src_port->name(), pkt->cmdString(), pkt->getAddr()); 258 return false; 259 } 260 261 DPRINTF(CoherentBus, "recvTimingSnoop: src %s %s 0x%x\n", 262 src_port->name(), pkt->cmdString(), pkt->getAddr()); 263 264 // get the destination from the packet 265 PortID dest = pkt->getDest(); 266 267 // responses are never express snoops 268 assert(!pkt->isExpressSnoop()); 269 270 calcPacketTiming(pkt); 271 Tick packetFinishTime = pkt->finishTime; 272 273 // determine if the response is from a snoop request we 274 // created as the result of a normal request (in which case it 275 // should be in the outstandingReq), or if we merely forwarded 276 // someone else's snoop request 277 if (outstandingReq.find(pkt->req) == outstandingReq.end()) { 278 // this is a snoop response to a snoop request we 279 // forwarded, e.g. coming from the L1 and going to the L2 280 // this should be forwarded as a snoop response 281 bool success M5_VAR_USED = masterPorts[dest]->sendTimingSnoopResp(pkt); 282 assert(success); 283 } else { 284 // we got a snoop response on one of our slave ports, 285 // i.e. from a coherent master connected to the bus, and 286 // since we created the snoop request as part of 287 // recvTiming, this should now be a normal response again 288 outstandingReq.erase(pkt->req); 289 290 // this is a snoop response from a coherent master, with a 291 // destination field set on its way through the bus as 292 // request, hence it should never go back to where the 293 // snoop response came from, but instead to where the 294 // original request came from 295 assert(slave_port_id != dest); 296 297 // as a normal response, it should go back to a master 298 // through one of our slave ports 299 bool success M5_VAR_USED = slavePorts[dest]->sendTimingResp(pkt); 300 301 // currently it is illegal to block responses... can lead 302 // to deadlock 303 assert(success); 304 } 305 306 succeededTiming(packetFinishTime); 307 308 return true; 309} 310 311 312void 313CoherentBus::forwardTiming(PacketPtr pkt, PortID exclude_slave_port_id) 314{ 315 for (SlavePortIter s = snoopPorts.begin(); s != snoopPorts.end(); ++s) { 316 SlavePort *p = *s; 317 // we could have gotten this request from a snooping master 318 // (corresponding to our own slave port that is also in 319 // snoopPorts) and should not send it back to where it came 320 // from 321 if (exclude_slave_port_id == InvalidPortID || 322 p->getId() != exclude_slave_port_id) { 323 // cache is not allowed to refuse snoop 324 p->sendTimingSnoopReq(pkt); 325 } 326 } 327} 328 329Tick 330CoherentBus::recvAtomic(PacketPtr pkt, PortID slave_port_id) 331{ 332 DPRINTF(CoherentBus, "recvAtomic: packet src %s addr 0x%x cmd %s\n", 333 slavePorts[slave_port_id]->name(), pkt->getAddr(), 334 pkt->cmdString()); 335 336 MemCmd snoop_response_cmd = MemCmd::InvalidCmd; 337 Tick snoop_response_latency = 0; 338 339 // uncacheable requests need never be snooped 340 if (!pkt->req->isUncacheable()) { 341 // forward to all snoopers but the source 342 std::pair<MemCmd, Tick> snoop_result = 343 forwardAtomic(pkt, slave_port_id); 344 snoop_response_cmd = snoop_result.first; 345 snoop_response_latency = snoop_result.second; 346 } 347 348 // even if we had a snoop response, we must continue and also 349 // perform the actual request at the destination 350 PortID dest_id = findPort(pkt->getAddr()); 351 352 // forward the request to the appropriate destination 353 Tick response_latency = masterPorts[dest_id]->sendAtomic(pkt); 354 355 // if we got a response from a snooper, restore it here 356 if (snoop_response_cmd != MemCmd::InvalidCmd) { 357 // no one else should have responded 358 assert(!pkt->isResponse()); 359 pkt->cmd = snoop_response_cmd; 360 response_latency = snoop_response_latency; 361 } 362 363 pkt->finishTime = curTick() + response_latency; 364 return response_latency; 365} 366 367Tick 368CoherentBus::recvAtomicSnoop(PacketPtr pkt, PortID master_port_id) 369{ 370 DPRINTF(CoherentBus, "recvAtomicSnoop: packet src %s addr 0x%x cmd %s\n", 371 masterPorts[master_port_id]->name(), pkt->getAddr(), 372 pkt->cmdString()); 373 374 // forward to all snoopers 375 std::pair<MemCmd, Tick> snoop_result = 376 forwardAtomic(pkt, InvalidPortID); 377 MemCmd snoop_response_cmd = snoop_result.first; 378 Tick snoop_response_latency = snoop_result.second; 379 380 if (snoop_response_cmd != MemCmd::InvalidCmd) 381 pkt->cmd = snoop_response_cmd; 382 383 pkt->finishTime = curTick() + snoop_response_latency; 384 return snoop_response_latency; 385} 386 387std::pair<MemCmd, Tick> 388CoherentBus::forwardAtomic(PacketPtr pkt, PortID exclude_slave_port_id) 389{ 390 // the packet may be changed on snoops, record the original 391 // command to enable us to restore it between snoops so that 392 // additional snoops can take place properly 393 MemCmd orig_cmd = pkt->cmd; 394 MemCmd snoop_response_cmd = MemCmd::InvalidCmd; 395 Tick snoop_response_latency = 0; 396 397 for (SlavePortIter s = snoopPorts.begin(); s != snoopPorts.end(); ++s) { 398 SlavePort *p = *s; 399 // we could have gotten this request from a snooping master 400 // (corresponding to our own slave port that is also in 401 // snoopPorts) and should not send it back to where it came 402 // from 403 if (exclude_slave_port_id == InvalidPortID || 404 p->getId() != exclude_slave_port_id) { 405 Tick latency = p->sendAtomicSnoop(pkt); 406 // in contrast to a functional access, we have to keep on 407 // going as all snoopers must be updated even if we get a 408 // response 409 if (pkt->isResponse()) { 410 // response from snoop agent 411 assert(pkt->cmd != orig_cmd); 412 assert(pkt->memInhibitAsserted()); 413 // should only happen once 414 assert(snoop_response_cmd == MemCmd::InvalidCmd); 415 // save response state 416 snoop_response_cmd = pkt->cmd; 417 snoop_response_latency = latency; 418 // restore original packet state for remaining snoopers 419 pkt->cmd = orig_cmd; 420 } 421 } 422 } 423 424 // the packet is restored as part of the loop and any potential 425 // snoop response is part of the returned pair 426 return std::make_pair(snoop_response_cmd, snoop_response_latency); 427} 428 429void 430CoherentBus::recvFunctional(PacketPtr pkt, PortID slave_port_id) 431{ 432 if (!pkt->isPrint()) { 433 // don't do DPRINTFs on PrintReq as it clutters up the output 434 DPRINTF(CoherentBus, 435 "recvFunctional: packet src %s addr 0x%x cmd %s\n", 436 slavePorts[slave_port_id]->name(), pkt->getAddr(), 437 pkt->cmdString()); 438 } 439 440 // uncacheable requests need never be snooped 441 if (!pkt->req->isUncacheable()) { 442 // forward to all snoopers but the source 443 forwardFunctional(pkt, slave_port_id); 444 } 445 446 // there is no need to continue if the snooping has found what we 447 // were looking for and the packet is already a response 448 if (!pkt->isResponse()) { 449 PortID dest_id = findPort(pkt->getAddr()); 450 451 masterPorts[dest_id]->sendFunctional(pkt); 452 } 453} 454 455void 456CoherentBus::recvFunctionalSnoop(PacketPtr pkt, PortID master_port_id) 457{ 458 if (!pkt->isPrint()) { 459 // don't do DPRINTFs on PrintReq as it clutters up the output 460 DPRINTF(CoherentBus, 461 "recvFunctionalSnoop: packet src %s addr 0x%x cmd %s\n", 462 masterPorts[master_port_id]->name(), pkt->getAddr(), 463 pkt->cmdString()); 464 } 465 466 // forward to all snoopers 467 forwardFunctional(pkt, InvalidPortID); 468} 469 470void 471CoherentBus::forwardFunctional(PacketPtr pkt, PortID exclude_slave_port_id) 472{ 473 for (SlavePortIter s = snoopPorts.begin(); s != snoopPorts.end(); ++s) { 474 SlavePort *p = *s; 475 // we could have gotten this request from a snooping master 476 // (corresponding to our own slave port that is also in 477 // snoopPorts) and should not send it back to where it came 478 // from 479 if (exclude_slave_port_id == InvalidPortID || 480 p->getId() != exclude_slave_port_id) 481 p->sendFunctionalSnoop(pkt); 482 483 // if we get a response we are done 484 if (pkt->isResponse()) { 485 break; 486 } 487 } 488} 489 490CoherentBus * 491CoherentBusParams::create() 492{ 493 return new CoherentBus(this); 494} 495