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