src/mem/bus.hh

   1 /*
   2  * Copyright (c) 2002-2005 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: Ron Dreslinski
  29  *          Ali Saidi
  30  */
  31
  32 /**
  33  * @file
  34  * Declaration of a bus object.
  35  */
  36
  37 #ifndef __MEM_BUS_HH__
  38 #define __MEM_BUS_HH__
  39
  40 #include <string>
  41 #include <set>
  42 #include <list>
  43
  44 #include "base/hashmap.hh"
  45 #include "base/range.hh"
  46 #include "base/range_map.hh"
  47 #include "base/types.hh"
  48 #include "mem/mem_object.hh"
  49 #include "mem/packet.hh"
  50 #include "mem/port.hh"
  51 #include "mem/request.hh"
  52 #include "params/Bus.hh"
  53 #include "sim/eventq.hh"
  54
  55 class Bus : public MemObject
  56 {
  57     /** Declaration of the buses port type, one will be instantiated for each
  58         of the interfaces connecting to the bus. */
  59     class BusPort : public Port
  60     {
  61         bool _onRetryList;
  62
  63         /** A pointer to the bus to which this port belongs. */
  64         Bus *bus;
  65
  66         /** A id to keep track of the intercafe ID this port is connected to. */
  67         int id;
  68
  69       public:
  70
  71         /** Constructor for the BusPort.*/
  72         BusPort(const std::string &_name, Bus *_bus, int _id)
  73             : Port(_name, _bus), _onRetryList(false), bus(_bus), id(_id)
  74         { }
  75
  76         bool onRetryList()
  77         { return _onRetryList; }
  78
  79         void onRetryList(bool newVal)
  80         { _onRetryList = newVal; }
  81
  82         int getId() { return id; }
  83
  84       protected:
  85
  86         /** When reciving a timing request from the peer port (at id),
  87             pass it to the bus. */
  88         virtual bool recvTiming(PacketPtr pkt)
  89         { pkt->setSrc(id); return bus->recvTiming(pkt); }
  90
  91         /** When reciving a Atomic requestfrom the peer port (at id),
  92             pass it to the bus. */
  93         virtual Tick recvAtomic(PacketPtr pkt)
  94         { pkt->setSrc(id); return bus->recvAtomic(pkt); }
  95
  96         /** When reciving a Functional requestfrom the peer port (at id),
  97             pass it to the bus. */
  98         virtual void recvFunctional(PacketPtr pkt)
  99         { pkt->setSrc(id); bus->recvFunctional(pkt); }
 100
 101         /** When reciving a status changefrom the peer port (at id),
 102             pass it to the bus. */
 103         virtual void recvStatusChange(Status status)
 104         { bus->recvStatusChange(status, id); }
 105
 106         /** When reciving a retry from the peer port (at id),
 107             pass it to the bus. */
 108         virtual void recvRetry()
 109         { bus->recvRetry(id); }
 110
 111         // This should return all the 'owned' addresses that are
 112         // downstream from this bus, yes?  That is, the union of all
 113         // the 'owned' address ranges of all the other interfaces on
 114         // this bus...
 115         virtual void getDeviceAddressRanges(AddrRangeList &resp,
 116                                             bool &snoop)
 117         { bus->addressRanges(resp, snoop, id); }
 118
 119         // Ask the bus to ask everyone on the bus what their block size is and
 120         // take the max of it. This might need to be changed a bit if we ever
 121         // support multiple block sizes.
 122         virtual unsigned deviceBlockSize() const
 123         { return bus->findBlockSize(id); }
 124
 125     };
 126
 127     class BusFreeEvent : public Event
 128     {
 129         Bus * bus;
 130
 131       public:
 132         BusFreeEvent(Bus * _bus);
 133         void process();
 134         const char *description() const;
 135     };
 136
 137     /** a globally unique id for this bus. */
 138     int busId;
 139     /** the clock speed for the bus */
 140     int clock;
 141     /** cycles of overhead per transaction */
 142     int headerCycles;
 143     /** the width of the bus in bytes */
 144     int width;
 145     /** the next tick at which the bus will be idle */
 146     Tick tickNextIdle;
 147
 148     Event * drainEvent;
 149
 150
 151     static const int defaultId = -3; //Make it unique from Broadcast
 152
 153     typedef range_map<Addr,int>::iterator PortIter;
 154     range_map<Addr, int> portMap;
 155
 156     AddrRangeList defaultRange;
 157
 158     typedef std::vector<BusPort*>::iterator SnoopIter;
 159     std::vector<BusPort*> snoopPorts;
 160
 161     /** Function called by the port when the bus is recieving a Timing
 162       transaction.*/
 163     bool recvTiming(PacketPtr pkt);
 164
 165     /** Function called by the port when the bus is recieving a Atomic
 166       transaction.*/
 167     Tick recvAtomic(PacketPtr pkt);
 168
 169     /** Function called by the port when the bus is recieving a Functional
 170         transaction.*/
 171     void recvFunctional(PacketPtr pkt);
 172
 173     /** Timing function called by port when it is once again able to process
 174      * requests. */
 175     void recvRetry(int id);
 176
 177     /** Function called by the port when the bus is recieving a status change.*/
 178     void recvStatusChange(Port::Status status, int id);
 179
 180     /** Find which port connected to this bus (if any) should be given a packet
 181      * with this address.
 182      * @param addr Address to find port for.
 183      * @return id of port that the packet should be sent out of.
 184      */
 185     int findPort(Addr addr);
 186
 187     // Cache for the findPort function storing recently used ports from portMap
 188     struct PortCache {
 189         bool valid;
 190         int  id;
 191         Addr start;
 192         Addr end;
 193     };
 194
 195     PortCache portCache[3];
 196
 197     // Checks the cache and returns the id of the port that has the requested
 198     // address within its range
 199     inline int checkPortCache(Addr addr) {
 200         if (portCache[0].valid && addr >= portCache[0].start &&
 201             addr < portCache[0].end) {
 202             return portCache[0].id;
 203         }
 204         if (portCache[1].valid && addr >= portCache[1].start &&
 205                    addr < portCache[1].end) {
 206             return portCache[1].id;
 207         }
 208         if (portCache[2].valid && addr >= portCache[2].start &&
 209             addr < portCache[2].end) {
 210             return portCache[2].id;
 211         }
 212
 213         return -1;
 214     }
 215
 216     // Clears the earliest entry of the cache and inserts a new port entry
 217     inline void updatePortCache(short id, Addr start, Addr end) {
 218         portCache[2].valid = portCache[1].valid;
 219         portCache[2].id    = portCache[1].id;
 220         portCache[2].start = portCache[1].start;
 221         portCache[2].end   = portCache[1].end;
 222
 223         portCache[1].valid = portCache[0].valid;
 224         portCache[1].id    = portCache[0].id;
 225         portCache[1].start = portCache[0].start;
 226         portCache[1].end   = portCache[0].end;
 227
 228         portCache[0].valid = true;
 229         portCache[0].id    = id;
 230         portCache[0].start = start;
 231         portCache[0].end   = end;
 232     }
 233
 234     // Clears the cache. Needs to be called in constructor.
 235     inline void clearPortCache() {
 236         portCache[2].valid = false;
 237         portCache[1].valid = false;
 238         portCache[0].valid = false;
 239     }
 240
 241     /** Process address range request.
 242      * @param resp addresses that we can respond to
 243      * @param snoop addresses that we would like to snoop
 244      * @param id ide of the busport that made the request.
 245      */
 246     void addressRanges(AddrRangeList &resp, bool &snoop, int id);
 247
 248     /** Calculate the timing parameters for the packet.  Updates the
 249      * firstWordTime and finishTime fields of the packet object.
 250      * Returns the tick at which the packet header is completed (which
 251      * will be all that is sent if the target rejects the packet).
 252      */
 253     Tick calcPacketTiming(PacketPtr pkt);
 254
 255     /** Occupy the bus until until */
 256     void occupyBus(Tick until);
 257
 258     /** Ask everyone on the bus what their size is
 259      * @param id id of the busport that made the request
 260      * @return the max of all the sizes
 261      */
 262     unsigned findBlockSize(int id);
 263
 264     BusFreeEvent busIdle;
 265
 266     bool inRetry;
 267     std::set<int> inRecvStatusChange;
 268
 269     /** max number of bus ids we've handed out so far */
 270     short maxId;
 271
 272     /** An array of pointers to the peer port interfaces
 273         connected to this bus.*/
 274     m5::hash_map<short,BusPort*> interfaces;
 275
 276     /** An array of pointers to ports that retry should be called on because the
 277      * original send failed for whatever reason.*/
 278     std::list<BusPort*> retryList;
 279
 280     void addToRetryList(BusPort * port)
 281     {
 282         if (!inRetry) {
 283             // The device wasn't retrying a packet, or wasn't at an appropriate
 284             // time.
 285             assert(!port->onRetryList());
 286             port->onRetryList(true);
 287             retryList.push_back(port);
 288         } else {
 289             if (port->onRetryList()) {
 290                 // The device was retrying a packet. It didn't work, so we'll leave
 291                 // it at the head of the retry list.
 292                 assert(port == retryList.front());
 293                 inRetry = false;
 294             }
 295             else {
 296                 port->onRetryList(true);
 297                 retryList.push_back(port);
 298             }
 299         }
 300     }
 301
 302     /** Port that handles requests that don't match any of the interfaces.*/
 303     BusPort *defaultPort;
 304
 305     BusPort *funcPort;
 306     int funcPortId;
 307
 308     /** If true, use address range provided by default device.  Any
 309        address not handled by another port and not in default device's
 310        range will cause a fatal error.  If false, just send all
 311        addresses not handled by another port to default device. */
 312     bool useDefaultRange;
 313
 314     unsigned defaultBlockSize;
 315     unsigned cachedBlockSize;
 316     bool cachedBlockSizeValid;
 317
 318    // Cache for the peer port interfaces
 319     struct BusCache {
 320         bool  valid;
 321         short id;
 322         BusPort  *port;
 323     };
 324
 325     BusCache busCache[3];
 326
 327     // Checks the peer port interfaces cache for the port id and returns
 328     // a pointer to the matching port
 329     inline BusPort* checkBusCache(short id) {
 330         if (busCache[0].valid && id == busCache[0].id) {
 331             return busCache[0].port;
 332         }
 333         if (busCache[1].valid && id == busCache[1].id) {
 334             return busCache[1].port;
 335         }
 336         if (busCache[2].valid && id == busCache[2].id) {
 337             return busCache[2].port;
 338         }
 339
 340         return NULL;
 341     }
 342
 343     // Replaces the earliest entry in the cache with a new entry
 344     inline void updateBusCache(short id, BusPort *port) {
 345         busCache[2].valid = busCache[1].valid;
 346         busCache[2].id    = busCache[1].id;
 347         busCache[2].port  = busCache[1].port;
 348
 349         busCache[1].valid = busCache[0].valid;
 350         busCache[1].id    = busCache[0].id;
 351         busCache[1].port  = busCache[0].port;
 352
 353         busCache[0].valid = true;
 354         busCache[0].id    = id;
 355         busCache[0].port  = port;
 356     }
 357
 358     // Invalidates the cache. Needs to be called in constructor.
 359     inline void clearBusCache() {
 360         busCache[2].valid = false;
 361         busCache[1].valid = false;
 362         busCache[0].valid = false;
 363     }
 364
 365
 366   public:
 367
 368     /** A function used to return the port associated with this bus object. */
 369     virtual Port *getPort(const std::string &if_name, int idx = -1);
 370     virtual void deletePortRefs(Port *p);
 371
 372     virtual void init();
 373     virtual void startup();
 374
 375     unsigned int drain(Event *de);
 376
 377     Bus(const BusParams *p);
 378 };
 379
 380 #endif //__MEM_BUS_HH__