bridge.hh revision 5386:5614618f4027 
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 *          Steve Reinhardt
30 */
31
32/**
33 * @file
34 * Declaration of a simple bus bridge object with no buffering
35 */
36
37#ifndef __MEM_BRIDGE_HH__
38#define __MEM_BRIDGE_HH__
39
40#include <string>
41#include <list>
42#include <inttypes.h>
43#include <queue>
44
45#include "base/fast_alloc.hh"
46#include "mem/mem_object.hh"
47#include "mem/packet.hh"
48#include "mem/port.hh"
49#include "params/Bridge.hh"
50#include "sim/eventq.hh"
51
52class Bridge : public MemObject
53{
54  protected:
55    /** Declaration of the buses port type, one will be instantiated for each
56        of the interfaces connecting to the bus. */
57    class BridgePort : public Port
58    {
59        /** A pointer to the bridge to which this port belongs. */
60        Bridge *bridge;
61
62        /**
63         * Pointer to the port on the other side of the bridge
64         * (connected to the other bus).
65         */
66        BridgePort *otherPort;
67
68        /** Minimum delay though this bridge. */
69        Tick delay;
70
71        /** Min delay to respond to a nack. */
72        Tick nackDelay;
73
74        /** Pass ranges from one side of the bridge to the other? */
75        std::vector<Range<Addr> > filterRanges;
76
77        class PacketBuffer : public Packet::SenderState, public FastAlloc {
78
79          public:
80            Tick ready;
81            PacketPtr pkt;
82            bool nackedHere;
83            Packet::SenderState *origSenderState;
84            short origSrc;
85            bool expectResponse;
86
87            PacketBuffer(PacketPtr _pkt, Tick t, bool nack = false)
88                : ready(t), pkt(_pkt), nackedHere(nack),
89                  origSenderState(_pkt->senderState),
90                  origSrc(nack ? _pkt->getDest() : _pkt->getSrc() ),
91                  expectResponse(_pkt->needsResponse() && !nack)
92
93            {
94                if (!pkt->isResponse() && !nack)
95                    pkt->senderState = this;
96            }
97
98            void fixResponse(PacketPtr pkt)
99            {
100                assert(pkt->senderState == this);
101                pkt->setDest(origSrc);
102                pkt->senderState = origSenderState;
103            }
104        };
105
106        /**
107         * Outbound packet queue.  Packets are held in this queue for a
108         * specified delay to model the processing delay of the
109         * bridge.
110         */
111        std::list<PacketBuffer*> sendQueue;
112
113        int outstandingResponses;
114        int queuedRequests;
115
116        /** If we're waiting for a retry to happen.*/
117        bool inRetry;
118
119        /** Max queue size for outbound packets */
120        int reqQueueLimit;
121
122        /** Max queue size for reserved responses. */
123        int respQueueLimit;
124
125        /**
126         * Is this side blocked from accepting outbound packets?
127         */
128        bool respQueueFull();
129        bool reqQueueFull();
130
131        void queueForSendTiming(PacketPtr pkt);
132
133        void finishSend(PacketBuffer *buf);
134
135        void nackRequest(PacketPtr pkt);
136
137        /**
138         * Handle send event, scheduled when the packet at the head of
139         * the outbound queue is ready to transmit (for timing
140         * accesses only).
141         */
142        void trySend();
143
144        class SendEvent : public Event
145        {
146            BridgePort *port;
147
148          public:
149            SendEvent(BridgePort *p)
150                : Event(&mainEventQueue), port(p) {}
151
152            virtual void process() { port->trySend(); }
153
154            virtual const char *description() const { return "bridge send"; }
155        };
156
157        SendEvent sendEvent;
158
159      public:
160        /** Constructor for the BusPort.*/
161        BridgePort(const std::string &_name, Bridge *_bridge,
162                BridgePort *_otherPort, int _delay, int _nack_delay,
163                int _req_limit, int _resp_limit,
164                std::vector<Range<Addr> > filter_ranges);
165
166      protected:
167
168        /** When receiving a timing request from the peer port,
169            pass it to the bridge. */
170        virtual bool recvTiming(PacketPtr pkt);
171
172        /** When receiving a retry request from the peer port,
173            pass it to the bridge. */
174        virtual void recvRetry();
175
176        /** When receiving a Atomic requestfrom the peer port,
177            pass it to the bridge. */
178        virtual Tick recvAtomic(PacketPtr pkt);
179
180        /** When receiving a Functional request from the peer port,
181            pass it to the bridge. */
182        virtual void recvFunctional(PacketPtr pkt);
183
184        /** When receiving a status changefrom the peer port,
185            pass it to the bridge. */
186        virtual void recvStatusChange(Status status);
187
188        /** When receiving a address range request the peer port,
189            pass it to the bridge. */
190        virtual void getDeviceAddressRanges(AddrRangeList &resp,
191                                            bool &snoop);
192    };
193
194    BridgePort portA, portB;
195
196    /** If this bridge should acknowledge writes. */
197    bool ackWrites;
198
199  public:
200    typedef BridgeParams Params;
201
202  protected:
203    Params *_params;
204
205  public:
206    const Params *params() const { return _params; }
207
208    /** A function used to return the port associated with this bus object. */
209    virtual Port *getPort(const std::string &if_name, int idx = -1);
210
211    virtual void init();
212
213    Bridge(Params *p);
214};
215
216#endif //__MEM_BUS_HH__
217