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         addToRetryList(pktPort);
  99         return false;
 100     }
 101
 102     short dest = pkt->getDest();
 103     if (dest == Packet::Broadcast) {
 104         if (timingSnoop(pkt)) {
 105             pkt->flags |= SNOOP_COMMIT;
 106             bool success = timingSnoop(pkt);
 107             assert(success);
 108             if (pkt->flags & SATISFIED) {
 109                 //Cache-Cache transfer occuring
 110                 if (inRetry) {
 111                     retryList.pop_front();
 112                     inRetry = false;
 113                 }
 114                 return true;
 115             }
 116             port = findPort(pkt->getAddr(), pkt->getSrc());
 117         } else {
 118             //Snoop didn't succeed
 119             addToRetryList(pktPort);
 120             return false;
 121         }
 122     } else {
 123         assert(dest >= 0 && dest < interfaces.size());
 124         assert(dest != pkt->getSrc()); // catch infinite loops
 125         port = interfaces[dest];
 126     }
 127
 128     //Bring tickNextIdle up to the present tick
 129     //There is some potential ambiguity where a cycle starts, which might make
 130     //a difference when devices are acting right around a cycle boundary. Using
 131     //a < allows things which happen exactly on a cycle boundary to take up only
 132     //the following cycle. Anthing that happens later will have to "wait" for
 133     //the end of that cycle, and then start using the bus after that.
 134     while (tickNextIdle < curTick)
 135         tickNextIdle += clock;
 136
 137     // The packet will be sent. Figure out how long it occupies the bus, and
 138     // how much of that time is for the first "word", aka bus width.
 139     int numCycles = 0;
 140     // Requests need one cycle to send an address
 141     if (pkt->isRequest())
 142         numCycles++;
 143     else if (pkt->isResponse() || pkt->hasData()) {
 144         // If a packet has data, it needs ceil(size/width) cycles to send it
 145         // We're using the "adding instead of dividing" trick again here
 146         if (pkt->hasData()) {
 147             int dataSize = pkt->getSize();
 148             for (int transmitted = 0; transmitted < dataSize;
 149                     transmitted += width) {
 150                 numCycles++;
 151             }
 152         } else {
 153             // If the packet didn't have data, it must have been a response.
 154             // Those use the bus for one cycle to send their data.
 155             numCycles++;
 156         }
 157     }
 158
 159     // The first word will be delivered after the current tick, the delivery
 160     // of the address if any, and one bus cycle to deliver the data
 161     pkt->firstWordTime =
 162         tickNextIdle +
 163         pkt->isRequest() ? clock : 0 +
 164         clock;
 165
 166     //Advance it numCycles bus cycles.
 167     //XXX Should this use the repeated addition trick as well?
 168     tickNextIdle += (numCycles * clock);
 169     if (!busIdle.scheduled()) {
 170         busIdle.schedule(tickNextIdle);
 171     } else {
 172         busIdle.reschedule(tickNextIdle);
 173     }
 174     DPRINTF(Bus, "The bus is now occupied from tick %d to %d\n",
 175             curTick, tickNextIdle);
 176
 177     // The bus will become idle once the current packet is delivered.
 178     pkt->finishTime = tickNextIdle;
 179
 180     if (port->sendTiming(pkt))  {
 181         // Packet was successfully sent. Return true.
 182         // Also take care of retries
 183         if (inRetry) {
 184             retryList.pop_front();
 185             inRetry = false;
 186         }
 187         return true;
 188     }
 189
 190     // Packet not successfully sent. Leave or put it on the retry list.
 191     addToRetryList(pktPort);
 192     return false;
 193 }
 194
 195 void
 196 Bus::recvRetry(int id)
 197 {
 198     // If there's anything waiting...
 199     if (retryList.size()) {
 200         //retryingPort = retryList.front();
 201         inRetry = true;
 202         retryList.front()->sendRetry();
 203         // If inRetry is still true, sendTiming wasn't called
 204         if (inRetry)
 205             panic("Port %s didn't call sendTiming in it's recvRetry\n",\
 206                     retryList.front()->getPeer()->name());
 207         //assert(!inRetry);
 208     }
 209 }
 210
 211 Port *
 212 Bus::findPort(Addr addr, int id)
 213 {
 214     /* An interval tree would be a better way to do this. --ali. */
 215     int dest_id = -1;
 216     int i = 0;
 217     bool found = false;
 218     AddrRangeIter iter;
 219
 220     while (i < portList.size() && !found)
 221     {
 222         if (portList[i].range == addr) {
 223             dest_id = portList[i].portId;
 224             found = true;
 225             DPRINTF(Bus, "  found addr %#llx on device %d\n", addr, dest_id);
 226         }
 227         i++;
 228     }
 229
 230     // Check if this matches the default range
 231     if (dest_id == -1) {
 232         for (iter = defaultRange.begin(); iter != defaultRange.end(); iter++) {
 233             if (*iter == addr) {
 234                 DPRINTF(Bus, "  found addr %#llx on default\n", addr);
 235                 return defaultPort;
 236             }
 237         }
 238         panic("Unable to find destination for addr: %#llx", addr);
 239     }
 240
 241
 242     // we shouldn't be sending this back to where it came from
 243     assert(dest_id != id);
 244
 245     return interfaces[dest_id];
 246 }
 247
 248 std::vector<int>
 249 Bus::findSnoopPorts(Addr addr, int id)
 250 {
 251     int i = 0;
 252     AddrRangeIter iter;
 253     std::vector<int> ports;
 254
 255     while (i < portSnoopList.size())
 256     {
 257         if (portSnoopList[i].range == addr && portSnoopList[i].portId != id) {
 258             //Careful  to not overlap ranges
 259             //or snoop will be called more than once on the port
 260             ports.push_back(portSnoopList[i].portId);
 261             DPRINTF(Bus, "  found snoop addr %#llx on device%d\n", addr,
 262                     portSnoopList[i].portId);
 263         }
 264         i++;
 265     }
 266     return ports;
 267 }
 268
 269 void
 270 Bus::atomicSnoop(Packet *pkt)
 271 {
 272     std::vector<int> ports = findSnoopPorts(pkt->getAddr(), pkt->getSrc());
 273
 274     while (!ports.empty())
 275     {
 276         interfaces[ports.back()]->sendAtomic(pkt);
 277         ports.pop_back();
 278     }
 279 }
 280
 281 void
 282 Bus::functionalSnoop(Packet *pkt)
 283 {
 284     std::vector<int> ports = findSnoopPorts(pkt->getAddr(), pkt->getSrc());
 285
 286     while (!ports.empty())
 287     {
 288         interfaces[ports.back()]->sendFunctional(pkt);
 289         ports.pop_back();
 290     }
 291 }
 292
 293 bool
 294 Bus::timingSnoop(Packet *pkt)
 295 {
 296     std::vector<int> ports = findSnoopPorts(pkt->getAddr(), pkt->getSrc());
 297     bool success = true;
 298
 299     while (!ports.empty() && success)
 300     {
 301         success = interfaces[ports.back()]->sendTiming(pkt);
 302         ports.pop_back();
 303     }
 304
 305     return success;
 306 }
 307
 308
 309 /** Function called by the port when the bus is receiving a Atomic
 310  * transaction.*/
 311 Tick
 312 Bus::recvAtomic(Packet *pkt)
 313 {
 314     DPRINTF(Bus, "recvAtomic: packet src %d dest %d addr 0x%x cmd %s\n",
 315             pkt->getSrc(), pkt->getDest(), pkt->getAddr(), pkt->cmdString());
 316     assert(pkt->getDest() == Packet::Broadcast);
 317     atomicSnoop(pkt);
 318     return findPort(pkt->getAddr(), pkt->getSrc())->sendAtomic(pkt);
 319 }
 320
 321 /** Function called by the port when the bus is receiving a Functional
 322  * transaction.*/
 323 void
 324 Bus::recvFunctional(Packet *pkt)
 325 {
 326     DPRINTF(Bus, "recvFunctional: packet src %d dest %d addr 0x%x cmd %s\n",
 327             pkt->getSrc(), pkt->getDest(), pkt->getAddr(), pkt->cmdString());
 328     assert(pkt->getDest() == Packet::Broadcast);
 329     functionalSnoop(pkt);
 330     findPort(pkt->getAddr(), pkt->getSrc())->sendFunctional(pkt);
 331 }
 332
 333 /** Function called by the port when the bus is receiving a status change.*/
 334 void
 335 Bus::recvStatusChange(Port::Status status, int id)
 336 {
 337     AddrRangeList ranges;
 338     AddrRangeList snoops;
 339     int x;
 340     AddrRangeIter iter;
 341
 342     assert(status == Port::RangeChange &&
 343            "The other statuses need to be implemented.");
 344
 345     DPRINTF(BusAddrRanges, "received RangeChange from device id %d\n", id);
 346
 347     if (id == defaultId) {
 348         defaultRange.clear();
 349         defaultPort->getPeerAddressRanges(ranges, snoops);
 350         assert(snoops.size() == 0);
 351         for(iter = ranges.begin(); iter != ranges.end(); iter++) {
 352             defaultRange.push_back(*iter);
 353             DPRINTF(BusAddrRanges, "Adding range %#llx - %#llx for default range\n",
 354                     iter->start, iter->end);
 355         }
 356     } else {
 357
 358         assert((id < interfaces.size() && id >= 0) || id == -1);
 359         Port *port = interfaces[id];
 360         std::vector<DevMap>::iterator portIter;
 361         std::vector<DevMap>::iterator snoopIter;
 362
 363         // Clean out any previously existent ids
 364         for (portIter = portList.begin(); portIter != portList.end(); ) {
 365             if (portIter->portId == id)
 366                 portIter = portList.erase(portIter);
 367             else
 368                 portIter++;
 369         }
 370
 371         for (snoopIter = portSnoopList.begin(); snoopIter != portSnoopList.end(); ) {
 372             if (snoopIter->portId == id)
 373                 snoopIter = portSnoopList.erase(snoopIter);
 374             else
 375                 snoopIter++;
 376         }
 377
 378         port->getPeerAddressRanges(ranges, snoops);
 379
 380         for(iter = snoops.begin(); iter != snoops.end(); iter++) {
 381             DevMap dm;
 382             dm.portId = id;
 383             dm.range = *iter;
 384
 385             DPRINTF(BusAddrRanges, "Adding snoop range %#llx - %#llx for id %d\n",
 386                     dm.range.start, dm.range.end, id);
 387             portSnoopList.push_back(dm);
 388         }
 389
 390         for(iter = ranges.begin(); iter != ranges.end(); iter++) {
 391             DevMap dm;
 392             dm.portId = id;
 393             dm.range = *iter;
 394
 395             DPRINTF(BusAddrRanges, "Adding range %#llx - %#llx for id %d\n",
 396                     dm.range.start, dm.range.end, id);
 397             portList.push_back(dm);
 398         }
 399     }
 400     DPRINTF(MMU, "port list has %d entries\n", portList.size());
 401
 402     // tell all our peers that our address range has changed.
 403     // Don't tell the device that caused this change, it already knows
 404     for (x = 0; x < interfaces.size(); x++)
 405         if (x != id)
 406             interfaces[x]->sendStatusChange(Port::RangeChange);
 407
 408     if (id != defaultId && defaultPort)
 409         defaultPort->sendStatusChange(Port::RangeChange);
 410 }
 411
 412 void
 413 Bus::addressRanges(AddrRangeList &resp, AddrRangeList &snoop, int id)
 414 {
 415     std::vector<DevMap>::iterator portIter;
 416     AddrRangeIter dflt_iter;
 417     bool subset;
 418
 419     resp.clear();
 420     snoop.clear();
 421
 422     DPRINTF(BusAddrRanges, "received address range request, returning:\n");
 423
 424     for (dflt_iter = defaultRange.begin(); dflt_iter != defaultRange.end();
 425             dflt_iter++) {
 426         resp.push_back(*dflt_iter);
 427         DPRINTF(BusAddrRanges, "  -- %#llx : %#llx\n",dflt_iter->start,
 428                 dflt_iter->end);
 429     }
 430     for (portIter = portList.begin(); portIter != portList.end(); portIter++) {
 431         subset = false;
 432         for (dflt_iter = defaultRange.begin(); dflt_iter != defaultRange.end();
 433                 dflt_iter++) {
 434             if ((portIter->range.start < dflt_iter->start &&
 435                 portIter->range.end >= dflt_iter->start) ||
 436                (portIter->range.start < dflt_iter->end &&
 437                 portIter->range.end >= dflt_iter->end))
 438                 fatal("Devices can not set ranges that itersect the default set\
 439                         but are not a subset of the default set.\n");
 440             if (portIter->range.start >= dflt_iter->start &&
 441                 portIter->range.end <= dflt_iter->end) {
 442                 subset = true;
 443                 DPRINTF(BusAddrRanges, "  -- %#llx : %#llx is a SUBSET\n",
 444                     portIter->range.start, portIter->range.end);
 445             }
 446         }
 447         if (portIter->portId != id && !subset) {
 448             resp.push_back(portIter->range);
 449             DPRINTF(BusAddrRanges, "  -- %#llx : %#llx\n",
 450                     portIter->range.start, portIter->range.end);
 451         }
 452     }
 453 }
 454
 455 BEGIN_DECLARE_SIM_OBJECT_PARAMS(Bus)
 456
 457     Param<int> bus_id;
 458     Param<int> clock;
 459     Param<int> width;
 460
 461 END_DECLARE_SIM_OBJECT_PARAMS(Bus)
 462
 463 BEGIN_INIT_SIM_OBJECT_PARAMS(Bus)
 464     INIT_PARAM(bus_id, "a globally unique bus id"),
 465     INIT_PARAM(clock, "bus clock speed"),
 466     INIT_PARAM(width, "width of the bus (bits)")
 467 END_INIT_SIM_OBJECT_PARAMS(Bus)
 468
 469 CREATE_SIM_OBJECT(Bus)
 470 {
 471     return new Bus(getInstanceName(), bus_id, clock, width);
 472 }
 473
 474 REGISTER_SIM_OBJECT("Bus", Bus)