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 <list>
  42 #include <inttypes.h>
  43
  44 #include "base/range.hh"
  45 #include "mem/mem_object.hh"
  46 #include "mem/packet.hh"
  47 #include "mem/port.hh"
  48 #include "mem/request.hh"
  49 #include "sim/eventq.hh"
  50
  51 class Bus : public MemObject
  52 {
  53     /** a globally unique id for this bus. */
  54     int busId;
  55     /** the clock speed for the bus */
  56     int clock;
  57     /** the width of the bus in bytes */
  58     int width;
  59     /** the next tick at which the bus will be idle */
  60     Tick tickNextIdle;
  61
  62     Event * drainEvent;
  63
  64     static const int defaultId = -3; //Make it unique from Broadcast
  65
  66     struct DevMap {
  67         int portId;
  68         Range<Addr> range;
  69     };
  70     std::vector<DevMap> portList;
  71     AddrRangeList defaultRange;
  72     std::vector<DevMap> portSnoopList;
  73
  74     /** Function called by the port when the bus is recieving a Timing
  75       transaction.*/
  76     bool recvTiming(PacketPtr pkt);
  77
  78     /** Function called by the port when the bus is recieving a Atomic
  79       transaction.*/
  80     Tick recvAtomic(PacketPtr pkt);
  81
  82     /** Function called by the port when the bus is recieving a Functional
  83         transaction.*/
  84     void recvFunctional(PacketPtr pkt);
  85
  86     /** Timing function called by port when it is once again able to process
  87      * requests. */
  88     void recvRetry(int id);
  89
  90     /** Function called by the port when the bus is recieving a status change.*/
  91     void recvStatusChange(Port::Status status, int id);
  92
  93     /** Find which port connected to this bus (if any) should be given a packet
  94      * with this address.
  95      * @param addr Address to find port for.
  96      * @param id Id of the port this packet was received from (to prevent
  97      *             loops)
  98      * @return pointer to port that the packet should be sent out of.
  99      */
 100     Port *findPort(Addr addr, int id);
 101
 102     /** Find all ports with a matching snoop range, except src port.  Keep in mind
 103      * that the ranges shouldn't overlap or you will get a double snoop to the same
 104      * interface.and the cache will assert out.
 105      * @param addr Address to find snoop prts for.
 106      * @param id Id of the src port of the request to avoid calling snoop on src
 107      * @return vector of IDs to snoop on
 108      */
 109     std::vector<int> findSnoopPorts(Addr addr, int id);
 110
 111     /** Snoop all relevant ports atomicly. */
 112     Tick atomicSnoop(PacketPtr pkt);
 113
 114     /** Snoop all relevant ports functionally. */
 115     void functionalSnoop(PacketPtr pkt);
 116
 117     /** Call snoop on caches, be sure to set SNOOP_COMMIT bit if you want
 118      * the snoop to happen
 119      * @return True if succeds.
 120      */
 121     bool timingSnoop(PacketPtr pkt);
 122
 123     /** Process address range request.
 124      * @param resp addresses that we can respond to
 125      * @param snoop addresses that we would like to snoop
 126      * @param id ide of the busport that made the request.
 127      */
 128     void addressRanges(AddrRangeList &resp, AddrRangeList &snoop, int id);
 129
 130     /** Occupy the bus with transmitting the packet pkt */
 131     void occupyBus(PacketPtr pkt);
 132
 133     /** Declaration of the buses port type, one will be instantiated for each
 134         of the interfaces connecting to the bus. */
 135     class BusPort : public Port
 136     {
 137         bool _onRetryList;
 138
 139         /** A pointer to the bus to which this port belongs. */
 140         Bus *bus;
 141
 142         /** A id to keep track of the intercafe ID this port is connected to. */
 143         int id;
 144
 145       public:
 146
 147         /** Constructor for the BusPort.*/
 148         BusPort(const std::string &_name, Bus *_bus, int _id)
 149             : Port(_name, _bus), _onRetryList(false), bus(_bus), id(_id)
 150         { }
 151
 152         bool onRetryList()
 153         { return _onRetryList; }
 154
 155         void onRetryList(bool newVal)
 156         { _onRetryList = newVal; }
 157
 158       protected:
 159
 160         /** When reciving a timing request from the peer port (at id),
 161             pass it to the bus. */
 162         virtual bool recvTiming(PacketPtr pkt)
 163         { pkt->setSrc(id); return bus->recvTiming(pkt); }
 164
 165         /** When reciving a Atomic requestfrom the peer port (at id),
 166             pass it to the bus. */
 167         virtual Tick recvAtomic(PacketPtr pkt)
 168         { pkt->setSrc(id); return bus->recvAtomic(pkt); }
 169
 170         /** When reciving a Functional requestfrom the peer port (at id),
 171             pass it to the bus. */
 172         virtual void recvFunctional(PacketPtr pkt)
 173         { pkt->setSrc(id); bus->recvFunctional(pkt); }
 174
 175         /** When reciving a status changefrom the peer port (at id),
 176             pass it to the bus. */
 177         virtual void recvStatusChange(Status status)
 178         { bus->recvStatusChange(status, id); }
 179
 180         /** When reciving a retry from the peer port (at id),
 181             pass it to the bus. */
 182         virtual void recvRetry()
 183         { bus->recvRetry(id); }
 184
 185         // This should return all the 'owned' addresses that are
 186         // downstream from this bus, yes?  That is, the union of all
 187         // the 'owned' address ranges of all the other interfaces on
 188         // this bus...
 189         virtual void getDeviceAddressRanges(AddrRangeList &resp,
 190                                             AddrRangeList &snoop)
 191         { bus->addressRanges(resp, snoop, id); }
 192
 193         // Hack to make translating port work without changes
 194         virtual int deviceBlockSize() { return 32; }
 195
 196     };
 197
 198     class BusFreeEvent : public Event
 199     {
 200         Bus * bus;
 201
 202       public:
 203         BusFreeEvent(Bus * _bus);
 204         void process();
 205         const char *description();
 206     };
 207
 208     BusFreeEvent busIdle;
 209
 210     bool inRetry;
 211
 212     /** An array of pointers to the peer port interfaces
 213         connected to this bus.*/
 214     std::vector<BusPort*> interfaces;
 215
 216     /** An array of pointers to ports that retry should be called on because the
 217      * original send failed for whatever reason.*/
 218     std::list<BusPort*> retryList;
 219
 220     void addToRetryList(BusPort * port)
 221     {
 222         if (!inRetry) {
 223             // The device wasn't retrying a packet, or wasn't at an appropriate
 224             // time.
 225             assert(!port->onRetryList());
 226             port->onRetryList(true);
 227             retryList.push_back(port);
 228         } else {
 229             if (port->onRetryList()) {
 230                 // The device was retrying a packet. It didn't work, so we'll leave
 231                 // it at the head of the retry list.
 232                 assert(port == retryList.front());
 233                 inRetry = false;
 234             }
 235             else {
 236                 port->onRetryList(true);
 237                 retryList.push_back(port);
 238             }
 239         }
 240     }
 241
 242     /** Port that handles requests that don't match any of the interfaces.*/
 243     BusPort *defaultPort;
 244
 245     /** Has the user specified their own default responder? */
 246     bool responderSet;
 247
 248   public:
 249
 250     /** A function used to return the port associated with this bus object. */
 251     virtual Port *getPort(const std::string &if_name, int idx = -1);
 252
 253     virtual void init();
 254
 255     unsigned int drain(Event *de);
 256
 257     Bus(const std::string &n, int bus_id, int _clock, int _width,
 258         bool responder_set)
 259         : MemObject(n), busId(bus_id), clock(_clock), width(_width),
 260           tickNextIdle(0), busIdle(this), inRetry(false), defaultPort(NULL),
 261           responderSet(responder_set)
 262     {
 263         //Both the width and clock period must be positive
 264         if (width <= 0)
 265             fatal("Bus width must be positive\n");
 266         if (clock <= 0)
 267             fatal("Bus clock period must be positive\n");
 268     }
 269
 270 };
 271
 272 #endif //__MEM_BUS_HH__