src/mem/bus.cc

   1 /*
   2  * Copyright (c) 2006 The Regents of The University of Michigan
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions are
   7  * met: redistributions of source code must retain the above copyright
   8  * notice, this list of conditions and the following disclaimer;
   9  * redistributions in binary form must reproduce the above copyright
  10  * notice, this list of conditions and the following disclaimer in the
  11  * documentation and/or other materials provided with the distribution;
  12  * neither the name of the copyright holders nor the names of its
  13  * contributors may be used to endorse or promote products derived from
  14  * this software without specific prior written permission.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  17  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  18  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  19  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  20  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  21  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  22  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  26  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27  *
  28  * Authors: Ali Saidi
  29  */
  30
  31 /**
  32  * @file
  33  * Definition of a bus object.
  34  */
  35
  36
  37 #include "base/misc.hh"
  38 #include "base/trace.hh"
  39 #include "mem/bus.hh"
  40 #include "sim/builder.hh"
  41
  42 Port *
  43 Bus::getPort(const std::string &if_name, int idx)
  44 {
  45     if (if_name == "default")
  46         if (defaultPort == NULL) {
  47             defaultPort = new BusPort(csprintf("%s-default",name()), this,
  48                     defaultId);
  49             return defaultPort;
  50         } else
  51             fatal("Default port already set\n");
  52
  53     // if_name ignored?  forced to be empty?
  54     int id = interfaces.size();
  55     BusPort *bp = new BusPort(csprintf("%s-p%d", name(), id), this, id);
  56     interfaces.push_back(bp);
  57     return bp;
  58 }
  59
  60 /** Get the ranges of anyone other buses that we are connected to. */
  61 void
  62 Bus::init()
  63 {
  64     std::vector<Port*>::iterator intIter;
  65
  66     for (intIter = interfaces.begin(); intIter != interfaces.end(); intIter++)
  67         (*intIter)->sendStatusChange(Port::RangeChange);
  68 }
  69
  70 Bus::BusFreeEvent::BusFreeEvent(Bus *_bus) : Event(&mainEventQueue), bus(_bus)
  71 {}
  72
  73 void Bus::BusFreeEvent::process()
  74 {
  75     bus->recvRetry(-1);
  76 }
  77
  78 const char * Bus::BusFreeEvent::description()
  79 {
  80     return "bus became available";
  81 }
  82
  83 /** Function called by the port when the bus is receiving a Timing
  84  * transaction.*/
  85 bool
  86 Bus::recvTiming(Packet *pkt)
  87 {
  88     Port *port;
  89     DPRINTF(Bus, "recvTiming: packet src %d dest %d addr 0x%x cmd %s\n",
  90             pkt->getSrc(), pkt->getDest(), pkt->getAddr(), pkt->cmdString());
  91
  92     Port *pktPort = interfaces[pkt->getSrc()];
  93
  94     // If the bus is busy, or other devices are in line ahead of the current
  95     // one, put this device on the retry list.
  96     if (tickNextIdle > curTick ||
  97             (retryList.size() && (!inRetry || pktPort != retryList.front()))) {
  98         DPRINTF(Bus, "Adding RETRY for %i\n", pktPort);
  99         addToRetryList(pktPort);
 100         return false;
 101     }
 102
 103     short dest = pkt->getDest();
 104     if (dest == Packet::Broadcast) {
 105         if (timingSnoop(pkt)) {
 106             pkt->flags |= SNOOP_COMMIT;
 107             bool success = timingSnoop(pkt);
 108             assert(success);
 109             if (pkt->flags & SATISFIED) {
 110                 //Cache-Cache transfer occuring
 111                 if (inRetry) {
 112                     DPRINTF(Bus, "Removing RETRY %i\n", retryList.front());
 113                     retryList.pop_front();
 114                     inRetry = false;
 115                 }
 116                 return true;
 117             }
 118             port = findPort(pkt->getAddr(), pkt->getSrc());
 119         } else {
 120             //Snoop didn't succeed
 121             DPRINTF(Bus, "Snoop caused adding to RETRY list %i\n", pktPort);
 122             addToRetryList(pktPort);
 123             return false;
 124         }
 125     } else {
 126         assert(dest >= 0 && dest < interfaces.size());
 127         assert(dest != pkt->getSrc()); // catch infinite loops
 128         port = interfaces[dest];
 129     }
 130
 131     //Bring tickNextIdle up to the present tick
 132     //There is some potential ambiguity where a cycle starts, which might make
 133     //a difference when devices are acting right around a cycle boundary. Using
 134     //a < allows things which happen exactly on a cycle boundary to take up only
 135     //the following cycle. Anthing that happens later will have to "wait" for
 136     //the end of that cycle, and then start using the bus after that.
 137     while (tickNextIdle < curTick)
 138         tickNextIdle += clock;
 139
 140     // The packet will be sent. Figure out how long it occupies the bus, and
 141     // how much of that time is for the first "word", aka bus width.
 142     int numCycles = 0;
 143     // Requests need one cycle to send an address
 144     if (pkt->isRequest())
 145         numCycles++;
 146     else if (pkt->isResponse() || pkt->hasData()) {
 147         // If a packet has data, it needs ceil(size/width) cycles to send it
 148         // We're using the "adding instead of dividing" trick again here
 149         if (pkt->hasData()) {
 150             int dataSize = pkt->getSize();
 151             for (int transmitted = 0; transmitted < dataSize;
 152                     transmitted += width) {
 153                 numCycles++;
 154             }
 155         } else {
 156             // If the packet didn't have data, it must have been a response.
 157             // Those use the bus for one cycle to send their data.
 158             numCycles++;
 159         }
 160     }
 161
 162     // The first word will be delivered after the current tick, the delivery
 163     // of the address if any, and one bus cycle to deliver the data
 164     pkt->firstWordTime =
 165         tickNextIdle +
 166         pkt->isRequest() ? clock : 0 +
 167         clock;
 168
 169     //Advance it numCycles bus cycles.
 170     //XXX Should this use the repeated addition trick as well?
 171     tickNextIdle += (numCycles * clock);
 172     if (!busIdle.scheduled()) {
 173         busIdle.schedule(tickNextIdle);
 174     } else {
 175         busIdle.reschedule(tickNextIdle);
 176     }
 177     DPRINTF(Bus, "The bus is now occupied from tick %d to %d\n",
 178             curTick, tickNextIdle);
 179
 180     // The bus will become idle once the current packet is delivered.
 181     pkt->finishTime = tickNextIdle;
 182
 183     if (port->sendTiming(pkt))  {
 184         // Packet was successfully sent. Return true.
 185         // Also take care of retries
 186         if (inRetry) {
 187             DPRINTF(Bus, "Remove retry from list %i\n", retryList.front());
 188             retryList.pop_front();
 189             inRetry = false;
 190         }
 191         return true;
 192     }
 193
 194     // Packet not successfully sent. Leave or put it on the retry list.
 195     DPRINTF(Bus, "Adding a retry to RETRY list %i\n", pktPort);
 196     addToRetryList(pktPort);
 197     return false;
 198 }
 199
 200 void
 201 Bus::recvRetry(int id)
 202 {
 203     DPRINTF(Bus, "Received a retry\n");
 204     // If there's anything waiting...
 205     if (retryList.size()) {
 206         //retryingPort = retryList.front();
 207         inRetry = true;
 208         DPRINTF(Bus, "Sending a retry\n");
 209         retryList.front()->sendRetry();
 210         // If inRetry is still true, sendTiming wasn't called
 211         if (inRetry)
 212             panic("Port %s didn't call sendTiming in it's recvRetry\n",\
 213                     retryList.front()->getPeer()->name());
 214         //assert(!inRetry);
 215     }
 216 }
 217
 218 Port *
 219 Bus::findPort(Addr addr, int id)
 220 {
 221     /* An interval tree would be a better way to do this. --ali. */
 222     int dest_id = -1;
 223     int i = 0;
 224     bool found = false;
 225     AddrRangeIter iter;
 226
 227     while (i < portList.size() && !found)
 228     {
 229         if (portList[i].range == addr) {
 230             dest_id = portList[i].portId;
 231             found = true;
 232             DPRINTF(Bus, "  found addr %#llx on device %d\n", addr, dest_id);
 233         }
 234         i++;
 235     }
 236
 237     // Check if this matches the default range
 238     if (dest_id == -1) {
 239         for (iter = defaultRange.begin(); iter != defaultRange.end(); iter++) {
 240             if (*iter == addr) {
 241                 DPRINTF(Bus, "  found addr %#llx on default\n", addr);
 242                 return defaultPort;
 243             }
 244         }
 245         panic("Unable to find destination for addr: %#llx", addr);
 246     }
 247
 248
 249     // we shouldn't be sending this back to where it came from
 250     assert(dest_id != id);
 251
 252     return interfaces[dest_id];
 253 }
 254
 255 std::vector<int>
 256 Bus::findSnoopPorts(Addr addr, int id)
 257 {
 258     int i = 0;
 259     AddrRangeIter iter;
 260     std::vector<int> ports;
 261
 262     while (i < portSnoopList.size())
 263     {
 264         if (portSnoopList[i].range == addr && portSnoopList[i].portId != id) {
 265             //Careful  to not overlap ranges
 266             //or snoop will be called more than once on the port
 267             ports.push_back(portSnoopList[i].portId);
 268 //            DPRINTF(Bus, "  found snoop addr %#llx on device%d\n", addr,
 269 //                    portSnoopList[i].portId);
 270         }
 271         i++;
 272     }
 273     return ports;
 274 }
 275
 276 void
 277 Bus::atomicSnoop(Packet *pkt)
 278 {
 279     std::vector<int> ports = findSnoopPorts(pkt->getAddr(), pkt->getSrc());
 280
 281     while (!ports.empty())
 282     {
 283         interfaces[ports.back()]->sendAtomic(pkt);
 284         ports.pop_back();
 285     }
 286 }
 287
 288 void
 289 Bus::functionalSnoop(Packet *pkt)
 290 {
 291     std::vector<int> ports = findSnoopPorts(pkt->getAddr(), pkt->getSrc());
 292
 293     while (!ports.empty())
 294     {
 295         interfaces[ports.back()]->sendFunctional(pkt);
 296         ports.pop_back();
 297     }
 298 }
 299
 300 bool
 301 Bus::timingSnoop(Packet *pkt)
 302 {
 303     std::vector<int> ports = findSnoopPorts(pkt->getAddr(), pkt->getSrc());
 304     bool success = true;
 305
 306     while (!ports.empty() && success)
 307     {
 308         success = interfaces[ports.back()]->sendTiming(pkt);
 309         ports.pop_back();
 310     }
 311
 312     return success;
 313 }
 314
 315
 316 /** Function called by the port when the bus is receiving a Atomic
 317  * transaction.*/
 318 Tick
 319 Bus::recvAtomic(Packet *pkt)
 320 {
 321     DPRINTF(Bus, "recvAtomic: packet src %d dest %d addr 0x%x cmd %s\n",
 322             pkt->getSrc(), pkt->getDest(), pkt->getAddr(), pkt->cmdString());
 323     assert(pkt->getDest() == Packet::Broadcast);
 324     atomicSnoop(pkt);
 325     return findPort(pkt->getAddr(), pkt->getSrc())->sendAtomic(pkt);
 326 }
 327
 328 /** Function called by the port when the bus is receiving a Functional
 329  * transaction.*/
 330 void
 331 Bus::recvFunctional(Packet *pkt)
 332 {
 333     DPRINTF(Bus, "recvFunctional: packet src %d dest %d addr 0x%x cmd %s\n",
 334             pkt->getSrc(), pkt->getDest(), pkt->getAddr(), pkt->cmdString());
 335     assert(pkt->getDest() == Packet::Broadcast);
 336     functionalSnoop(pkt);
 337     findPort(pkt->getAddr(), pkt->getSrc())->sendFunctional(pkt);
 338 }
 339
 340 /** Function called by the port when the bus is receiving a status change.*/
 341 void
 342 Bus::recvStatusChange(Port::Status status, int id)
 343 {
 344     AddrRangeList ranges;
 345     AddrRangeList snoops;
 346     int x;
 347     AddrRangeIter iter;
 348
 349     assert(status == Port::RangeChange &&
 350            "The other statuses need to be implemented.");
 351
 352     DPRINTF(BusAddrRanges, "received RangeChange from device id %d\n", id);
 353
 354     if (id == defaultId) {
 355         defaultRange.clear();
 356         defaultPort->getPeerAddressRanges(ranges, snoops);
 357         assert(snoops.size() == 0);
 358         for(iter = ranges.begin(); iter != ranges.end(); iter++) {
 359             defaultRange.push_back(*iter);
 360             DPRINTF(BusAddrRanges, "Adding range %#llx - %#llx for default range\n",
 361                     iter->start, iter->end);
 362         }
 363     } else {
 364
 365         assert((id < interfaces.size() && id >= 0) || id == -1);
 366         Port *port = interfaces[id];
 367         std::vector<DevMap>::iterator portIter;
 368         std::vector<DevMap>::iterator snoopIter;
 369
 370         // Clean out any previously existent ids
 371         for (portIter = portList.begin(); portIter != portList.end(); ) {
 372             if (portIter->portId == id)
 373                 portIter = portList.erase(portIter);
 374             else
 375                 portIter++;
 376         }
 377
 378         for (snoopIter = portSnoopList.begin(); snoopIter != portSnoopList.end(); ) {
 379             if (snoopIter->portId == id)
 380                 snoopIter = portSnoopList.erase(snoopIter);
 381             else
 382                 snoopIter++;
 383         }
 384
 385         port->getPeerAddressRanges(ranges, snoops);
 386
 387         for(iter = snoops.begin(); iter != snoops.end(); iter++) {
 388             DevMap dm;
 389             dm.portId = id;
 390             dm.range = *iter;
 391
 392             DPRINTF(BusAddrRanges, "Adding snoop range %#llx - %#llx for id %d\n",
 393                     dm.range.start, dm.range.end, id);
 394             portSnoopList.push_back(dm);
 395         }
 396
 397         for(iter = ranges.begin(); iter != ranges.end(); iter++) {
 398             DevMap dm;
 399             dm.portId = id;
 400             dm.range = *iter;
 401
 402             DPRINTF(BusAddrRanges, "Adding range %#llx - %#llx for id %d\n",
 403                     dm.range.start, dm.range.end, id);
 404             portList.push_back(dm);
 405         }
 406     }
 407     DPRINTF(MMU, "port list has %d entries\n", portList.size());
 408
 409     // tell all our peers that our address range has changed.
 410     // Don't tell the device that caused this change, it already knows
 411     for (x = 0; x < interfaces.size(); x++)
 412         if (x != id)
 413             interfaces[x]->sendStatusChange(Port::RangeChange);
 414
 415     if (id != defaultId && defaultPort)
 416         defaultPort->sendStatusChange(Port::RangeChange);
 417 }
 418
 419 void
 420 Bus::addressRanges(AddrRangeList &resp, AddrRangeList &snoop, int id)
 421 {
 422     std::vector<DevMap>::iterator portIter;
 423     AddrRangeIter dflt_iter;
 424     bool subset;
 425
 426     resp.clear();
 427     snoop.clear();
 428
 429     DPRINTF(BusAddrRanges, "received address range request, returning:\n");
 430
 431     for (dflt_iter = defaultRange.begin(); dflt_iter != defaultRange.end();
 432             dflt_iter++) {
 433         resp.push_back(*dflt_iter);
 434         DPRINTF(BusAddrRanges, "  -- %#llx : %#llx\n",dflt_iter->start,
 435                 dflt_iter->end);
 436     }
 437     for (portIter = portList.begin(); portIter != portList.end(); portIter++) {
 438         subset = false;
 439         for (dflt_iter = defaultRange.begin(); dflt_iter != defaultRange.end();
 440                 dflt_iter++) {
 441             if ((portIter->range.start < dflt_iter->start &&
 442                 portIter->range.end >= dflt_iter->start) ||
 443                (portIter->range.start < dflt_iter->end &&
 444                 portIter->range.end >= dflt_iter->end))
 445                 fatal("Devices can not set ranges that itersect the default set\
 446                         but are not a subset of the default set.\n");
 447             if (portIter->range.start >= dflt_iter->start &&
 448                 portIter->range.end <= dflt_iter->end) {
 449                 subset = true;
 450                 DPRINTF(BusAddrRanges, "  -- %#llx : %#llx is a SUBSET\n",
 451                     portIter->range.start, portIter->range.end);
 452             }
 453         }
 454         if (portIter->portId != id && !subset) {
 455             resp.push_back(portIter->range);
 456             DPRINTF(BusAddrRanges, "  -- %#llx : %#llx\n",
 457                     portIter->range.start, portIter->range.end);
 458         }
 459     }
 460 }
 461
 462 BEGIN_DECLARE_SIM_OBJECT_PARAMS(Bus)
 463
 464     Param<int> bus_id;
 465     Param<int> clock;
 466     Param<int> width;
 467
 468 END_DECLARE_SIM_OBJECT_PARAMS(Bus)
 469
 470 BEGIN_INIT_SIM_OBJECT_PARAMS(Bus)
 471     INIT_PARAM(bus_id, "a globally unique bus id"),
 472     INIT_PARAM(clock, "bus clock speed"),
 473     INIT_PARAM(width, "width of the bus (bits)")
 474 END_INIT_SIM_OBJECT_PARAMS(Bus)
 475
 476 CREATE_SIM_OBJECT(Bus)
 477 {
 478     return new Bus(getInstanceName(), bus_id, clock, width);
 479 }
 480
 481 REGISTER_SIM_OBJECT("Bus", Bus)