src/mem/bus.hh

   1 /*
   2  * Copyright (c) 2011 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) 2002-2005 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: Ron Dreslinski
  41  *          Ali Saidi
  42  *          Andreas Hansson
  43  *          William Wang
  44  */
  45
  46 /**
  47  * @file
  48  * Declaration of a bus object.
  49  */
  50
  51 #ifndef __MEM_BUS_HH__
  52 #define __MEM_BUS_HH__
  53
  54 #include <list>
  55 #include <set>
  56 #include <string>
  57
  58 #include "base/range.hh"
  59 #include "base/range_map.hh"
  60 #include "base/types.hh"
  61 #include "mem/mem_object.hh"
  62 #include "mem/packet.hh"
  63 #include "mem/port.hh"
  64 #include "params/Bus.hh"
  65 #include "sim/eventq.hh"
  66
  67 class Bus : public MemObject
  68 {
  69     /**
  70      * Declaration of the bus slave port type, one will be
  71      * instantiated for each of the master interfaces connecting to
  72      * the bus.
  73      */
  74     class BusSlavePort : public SlavePort
  75     {
  76       private:
  77         /** A pointer to the bus to which this port belongs. */
  78         Bus *bus;
  79
  80         /** A id to keep track of the interface ID of this port. */
  81         int id;
  82
  83       public:
  84
  85         /** Constructor for the BusSlavePort.*/
  86         BusSlavePort(const std::string &_name, Bus *_bus, int _id)
  87             : SlavePort(_name, _bus), bus(_bus), id(_id)
  88         { }
  89
  90         int getId() const { return id; }
  91
  92       protected:
  93
  94         /**
  95          * When receiving a timing request, pass it to the bus.
  96          */
  97         virtual bool recvTiming(PacketPtr pkt)
  98         { pkt->setSrc(id); return bus->recvTiming(pkt); }
  99
 100         /**
 101          * When receiving a timing snoop response, pass it to the bus.
 102          */
 103         virtual bool recvTimingSnoop(PacketPtr pkt)
 104         { pkt->setSrc(id); return bus->recvTimingSnoop(pkt); }
 105
 106         /**
 107          * When receiving an atomic request, pass it to the bus.
 108          */
 109         virtual Tick recvAtomic(PacketPtr pkt)
 110         { pkt->setSrc(id); return bus->recvAtomic(pkt); }
 111
 112         /**
 113          * When receiving a functional request, pass it to the bus.
 114          */
 115         virtual void recvFunctional(PacketPtr pkt)
 116         { pkt->setSrc(id); bus->recvFunctional(pkt); }
 117
 118         /**
 119          * When receiving a retry, pass it to the bus.
 120          */
 121         virtual void recvRetry()
 122         { panic("Bus slave ports always succeed and should never retry.\n"); }
 123
 124         // This should return all the 'owned' addresses that are
 125         // downstream from this bus, yes?  That is, the union of all
 126         // the 'owned' address ranges of all the other interfaces on
 127         // this bus...
 128         virtual AddrRangeList getAddrRanges()
 129         { return bus->getAddrRanges(id); }
 130
 131         // Ask the bus to ask everyone on the bus what their block size is and
 132         // take the max of it. This might need to be changed a bit if we ever
 133         // support multiple block sizes.
 134         virtual unsigned deviceBlockSize() const
 135         { return bus->findBlockSize(id); }
 136
 137     };
 138
 139     /**
 140      * Declaration of the bus master port type, one will be
 141      * instantiated for each of the slave interfaces connecting to the
 142      * bus.
 143      */
 144     class BusMasterPort : public MasterPort
 145     {
 146       private:
 147         /** A pointer to the bus to which this port belongs. */
 148         Bus *bus;
 149
 150         /** A id to keep track of the interface ID of this port. */
 151         int id;
 152
 153       public:
 154
 155         /** Constructor for the BusMasterPort.*/
 156         BusMasterPort(const std::string &_name, Bus *_bus, int _id)
 157             : MasterPort(_name, _bus), bus(_bus), id(_id)
 158         { }
 159
 160         int getId() const { return id; }
 161
 162         /**
 163          * Determine if this port should be considered a snooper. This
 164          * is determined by the bus.
 165          *
 166          * @return a boolean that is true if this port is snooping
 167          */
 168         virtual bool isSnooping() const
 169         { return bus->isSnooping(id); }
 170
 171       protected:
 172
 173         /**
 174          * When receiving a timing response, pass it to the bus.
 175          */
 176         virtual bool recvTiming(PacketPtr pkt)
 177         { pkt->setSrc(id); return bus->recvTiming(pkt); }
 178
 179         /**
 180          * When receiving a timing snoop request, pass it to the bus.
 181          */
 182         virtual bool recvTimingSnoop(PacketPtr pkt)
 183         { pkt->setSrc(id); return bus->recvTimingSnoop(pkt); }
 184
 185         /**
 186          * When receiving an atomic snoop request, pass it to the bus.
 187          */
 188         virtual Tick recvAtomicSnoop(PacketPtr pkt)
 189         { pkt->setSrc(id); return bus->recvAtomicSnoop(pkt); }
 190
 191         /**
 192          * When receiving a functional snoop request, pass it to the bus.
 193          */
 194         virtual void recvFunctionalSnoop(PacketPtr pkt)
 195         { pkt->setSrc(id); bus->recvFunctionalSnoop(pkt); }
 196
 197         /** When reciving a range change from the peer port (at id),
 198             pass it to the bus. */
 199         virtual void recvRangeChange()
 200         { bus->recvRangeChange(id); }
 201
 202         /** When reciving a retry from the peer port (at id),
 203             pass it to the bus. */
 204         virtual void recvRetry()
 205         { bus->recvRetry(id); }
 206
 207         // Ask the bus to ask everyone on the bus what their block size is and
 208         // take the max of it. This might need to be changed a bit if we ever
 209         // support multiple block sizes.
 210         virtual unsigned deviceBlockSize() const
 211         { return bus->findBlockSize(id); }
 212
 213     };
 214
 215     /** the clock speed for the bus */
 216     int clock;
 217     /** cycles of overhead per transaction */
 218     int headerCycles;
 219     /** the width of the bus in bytes */
 220     int width;
 221     /** the next tick at which the bus will be idle */
 222     Tick tickNextIdle;
 223
 224     Event * drainEvent;
 225
 226     typedef range_map<Addr,int>::iterator PortIter;
 227     range_map<Addr, int> portMap;
 228
 229     AddrRangeList defaultRange;
 230
 231     typedef std::vector<BusSlavePort*>::iterator SnoopIter;
 232     std::vector<BusSlavePort*> snoopPorts;
 233
 234     /**
 235      * Store the outstanding requests so we can determine which ones
 236      * we generated and which ones were merely forwarded. This is used
 237      * in the coherent bus when coherency responses come back.
 238      */
 239     std::set<RequestPtr> outstandingReq;
 240
 241     /** Function called by the port when the bus is recieving a Timing
 242       transaction.*/
 243     bool recvTiming(PacketPtr pkt);
 244
 245     /** Function called by the port when the bus is recieving a timing
 246         snoop transaction.*/
 247     bool recvTimingSnoop(PacketPtr pkt);
 248
 249     /**
 250      * Forward a timing packet to our snoopers, potentially excluding
 251      * one of the connected coherent masters to avoid sending a packet
 252      * back to where it came from.
 253      *
 254      * @param pkt Packet to forward
 255      * @param exclude_slave_port_id Id of slave port to exclude
 256      */
 257     void forwardTiming(PacketPtr pkt, int exclude_slave_port_id);
 258
 259     /**
 260      * Determine if the bus is to be considered occupied when being
 261      * presented with a packet from a specific port. If so, the port
 262      * in question is also added to the retry list.
 263      *
 264      * @param pkt Incoming packet
 265      * @param port Source port on the bus presenting the packet
 266      *
 267      * @return True if the bus is to be considered occupied
 268      */
 269     bool isOccupied(PacketPtr pkt, Port* port);
 270
 271     /**
 272      * Deal with a destination port accepting a packet by potentially
 273      * removing the source port from the retry list (if retrying) and
 274      * occupying the bus accordingly.
 275      *
 276      * @param busy_time Time to spend as a result of a successful send
 277      */
 278     void succeededTiming(Tick busy_time);
 279
 280     /** Function called by the port when the bus is recieving a Atomic
 281       transaction.*/
 282     Tick recvAtomic(PacketPtr pkt);
 283
 284     /** Function called by the port when the bus is recieving an
 285         atomic snoop transaction.*/
 286     Tick recvAtomicSnoop(PacketPtr pkt);
 287
 288     /**
 289      * Forward an atomic packet to our snoopers, potentially excluding
 290      * one of the connected coherent masters to avoid sending a packet
 291      * back to where it came from.
 292      *
 293      * @param pkt Packet to forward
 294      * @param exclude_slave_port_id Id of slave port to exclude
 295      *
 296      * @return a pair containing the snoop response and snoop latency
 297      */
 298     std::pair<MemCmd, Tick> forwardAtomic(PacketPtr pkt,
 299                                           int exclude_slave_port_id);
 300
 301     /** Function called by the port when the bus is recieving a Functional
 302         transaction.*/
 303     void recvFunctional(PacketPtr pkt);
 304
 305     /** Function called by the port when the bus is recieving a functional
 306         snoop transaction.*/
 307     void recvFunctionalSnoop(PacketPtr pkt);
 308
 309     /**
 310      * Forward a functional packet to our snoopers, potentially
 311      * excluding one of the connected coherent masters to avoid
 312      * sending a packet back to where it came from.
 313      *
 314      * @param pkt Packet to forward
 315      * @param exclude_slave_port_id Id of slave port to exclude
 316      */
 317     void forwardFunctional(PacketPtr pkt, int exclude_slave_port_id);
 318
 319     /** Timing function called by port when it is once again able to process
 320      * requests. */
 321     void recvRetry(int id);
 322
 323     /** Function called by the port when the bus is recieving a range change.*/
 324     void recvRangeChange(int id);
 325
 326     /** Find which port connected to this bus (if any) should be given a packet
 327      * with this address.
 328      * @param addr Address to find port for.
 329      * @return id of port that the packet should be sent out of.
 330      */
 331     int findPort(Addr addr);
 332
 333     // Cache for the findPort function storing recently used ports from portMap
 334     struct PortCache {
 335         bool valid;
 336         int  id;
 337         Addr start;
 338         Addr end;
 339     };
 340
 341     PortCache portCache[3];
 342
 343     // Checks the cache and returns the id of the port that has the requested
 344     // address within its range
 345     inline int checkPortCache(Addr addr) {
 346         if (portCache[0].valid && addr >= portCache[0].start &&
 347             addr < portCache[0].end) {
 348             return portCache[0].id;
 349         }
 350         if (portCache[1].valid && addr >= portCache[1].start &&
 351                    addr < portCache[1].end) {
 352             return portCache[1].id;
 353         }
 354         if (portCache[2].valid && addr >= portCache[2].start &&
 355             addr < portCache[2].end) {
 356             return portCache[2].id;
 357         }
 358
 359         return INVALID_PORT_ID;
 360     }
 361
 362     // Clears the earliest entry of the cache and inserts a new port entry
 363     inline void updatePortCache(short id, Addr start, Addr end) {
 364         portCache[2].valid = portCache[1].valid;
 365         portCache[2].id    = portCache[1].id;
 366         portCache[2].start = portCache[1].start;
 367         portCache[2].end   = portCache[1].end;
 368
 369         portCache[1].valid = portCache[0].valid;
 370         portCache[1].id    = portCache[0].id;
 371         portCache[1].start = portCache[0].start;
 372         portCache[1].end   = portCache[0].end;
 373
 374         portCache[0].valid = true;
 375         portCache[0].id    = id;
 376         portCache[0].start = start;
 377         portCache[0].end   = end;
 378     }
 379
 380     // Clears the cache. Needs to be called in constructor.
 381     inline void clearPortCache() {
 382         portCache[2].valid = false;
 383         portCache[1].valid = false;
 384         portCache[0].valid = false;
 385     }
 386
 387     /**
 388      * Return the address ranges this port is responsible for.
 389      *
 390      * @param id id of the bus port that made the request
 391      *
 392      * @return a list of non-overlapping address ranges
 393      */
 394     AddrRangeList getAddrRanges(int id);
 395
 396     /**
 397      * Determine if the bus port is snooping or not.
 398      *
 399      * @param id id of the bus port that made the request
 400      *
 401      * @return a boolean indicating if this port is snooping or not
 402      */
 403     bool isSnooping(int id) const;
 404
 405     /** Calculate the timing parameters for the packet.  Updates the
 406      * firstWordTime and finishTime fields of the packet object.
 407      * Returns the tick at which the packet header is completed (which
 408      * will be all that is sent if the target rejects the packet).
 409      */
 410     Tick calcPacketTiming(PacketPtr pkt);
 411
 412     /** Occupy the bus until until */
 413     void occupyBus(Tick until);
 414
 415     /**
 416      * Release the bus after being occupied and return to an idle
 417      * state where we proceed to send a retry to any potential waiting
 418      * port, or drain if asked to do so.
 419      */
 420     void releaseBus();
 421
 422     /**
 423      * Send a retry to the port at the head of the retryList. The
 424      * caller must ensure that the list is not empty.
 425      */
 426     void retryWaiting();
 427
 428     /** Ask everyone on the bus what their size is
 429      * @param id id of the busport that made the request
 430      * @return the max of all the sizes
 431      */
 432     unsigned findBlockSize(int id);
 433
 434     // event used to schedule a release of the bus
 435     EventWrapper<Bus, &Bus::releaseBus> busIdleEvent;
 436
 437     bool inRetry;
 438     std::set<int> inRecvRangeChange;
 439
 440     /** The master and slave ports of the bus */
 441     std::vector<BusSlavePort*> slavePorts;
 442     std::vector<BusMasterPort*> masterPorts;
 443
 444     /** An array of pointers to ports that retry should be called on because the
 445      * original send failed for whatever reason.*/
 446     std::list<Port*> retryList;
 447
 448     void addToRetryList(Port* port)
 449     {
 450         if (!inRetry) {
 451             // The device wasn't retrying a packet, or wasn't at an
 452             // appropriate time.
 453             retryList.push_back(port);
 454         } else {
 455             if (!retryList.empty() && port == retryList.front()) {
 456                 // The device was retrying a packet. It didn't work,
 457                 // so we'll leave it at the head of the retry list.
 458                 inRetry = false;
 459             } else {
 460                 // We are in retry, but not for this port, put it at
 461                 // the end.
 462                 retryList.push_back(port);
 463             }
 464         }
 465     }
 466
 467     /** Port that handles requests that don't match any of the interfaces.*/
 468     short defaultPortId;
 469
 470     /** A symbolic name for a port id that denotes no port. */
 471     static const short INVALID_PORT_ID = -1;
 472
 473     /** If true, use address range provided by default device.  Any
 474        address not handled by another port and not in default device's
 475        range will cause a fatal error.  If false, just send all
 476        addresses not handled by another port to default device. */
 477     bool useDefaultRange;
 478
 479     unsigned defaultBlockSize;
 480     unsigned cachedBlockSize;
 481     bool cachedBlockSizeValid;
 482
 483   public:
 484
 485     /** A function used to return the port associated with this bus object. */
 486     virtual MasterPort& getMasterPort(const std::string& if_name, int idx = -1);
 487     virtual SlavePort& getSlavePort(const std::string& if_name, int idx = -1);
 488
 489     virtual void init();
 490     virtual void startup();
 491
 492     unsigned int drain(Event *de);
 493
 494     Bus(const BusParams *p);
 495 };
 496
 497 #endif //__MEM_BUS_HH__