bridge.hh revision 2665:a124942bacb8 
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 Decleration of a simple bus bridge object with no buffering
34 */
35
36#ifndef __MEM_BRIDGE_HH__
37#define __MEM_BRIDGE_HH__
38
39#include <string>
40#include <list>
41#include <inttypes.h>
42#include <queue>
43
44#include "mem/mem_object.hh"
45#include "mem/packet.hh"
46#include "mem/port.hh"
47#include "sim/eventq.hh"
48
49class Bridge : public MemObject
50{
51  protected:
52    /** Decleration of the buses port type, one will be instantiated for each
53        of the interfaces connecting to the bus. */
54    class BridgePort : public Port
55    {
56        /** A pointer to the bridge to which this port belongs. */
57        Bridge *bridge;
58
59        /**
60         * Pointer to the port on the other side of the bridge
61         * (connected to the other bus).
62         */
63        BridgePort *otherPort;
64
65        /** Minimum delay though this bridge. */
66        Tick delay;
67
68        class PacketBuffer : public Packet::SenderState {
69
70          public:
71            Tick ready;
72            Packet *pkt;
73            Packet::SenderState *origSenderState;
74            short origSrc;
75            bool expectResponse;
76
77            PacketBuffer(Packet *_pkt, Tick t)
78                : ready(t), pkt(_pkt),
79                  origSenderState(_pkt->senderState), origSrc(_pkt->getSrc()),
80                  expectResponse(_pkt->needsResponse())
81            {
82                if (!pkt->isResponse())
83                    pkt->senderState = this;
84            }
85
86            void fixResponse(Packet *pkt)
87            {
88                assert(pkt->senderState == this);
89                pkt->setDest(origSrc);
90                pkt->senderState = origSenderState;
91            }
92        };
93
94        /**
95         * Outbound packet queue.  Packets are held in this queue for a
96         * specified delay to model the processing delay of the
97         * bridge.
98         */
99        std::list<PacketBuffer*> sendQueue;
100
101        int outstandingResponses;
102
103        /** Max queue size for outbound packets */
104        int queueLimit;
105
106        /**
107         * Is this side blocked from accepting outbound packets?
108         */
109        bool queueFull() { return (sendQueue.size() == queueLimit); }
110
111        bool queueForSendTiming(Packet *pkt);
112
113        void finishSend(PacketBuffer *buf);
114
115        /**
116         * Handle send event, scheduled when the packet at the head of
117         * the outbound queue is ready to transmit (for timing
118         * accesses only).
119         */
120        void trySend();
121
122        class SendEvent : public Event
123        {
124            BridgePort *port;
125
126          public:
127            SendEvent(BridgePort *p)
128                : Event(&mainEventQueue), port(p) {}
129
130            virtual void process() { port->trySend(); }
131
132            virtual const char *description() { return "bridge send event"; }
133        };
134
135        SendEvent sendEvent;
136
137      public:
138
139        /** Constructor for the BusPort.*/
140        BridgePort(const std::string &_name,
141                   Bridge *_bridge, BridgePort *_otherPort,
142                   int _delay, int _queueLimit);
143
144      protected:
145
146        /** When receiving a timing request from the peer port,
147            pass it to the bridge. */
148        virtual bool recvTiming(Packet *pkt);
149
150        /** When receiving a retry request from the peer port,
151            pass it to the bridge. */
152        virtual void recvRetry();
153
154        /** When receiving a Atomic requestfrom the peer port,
155            pass it to the bridge. */
156        virtual Tick recvAtomic(Packet *pkt);
157
158        /** When receiving a Functional request from the peer port,
159            pass it to the bridge. */
160        virtual void recvFunctional(Packet *pkt);
161
162        /** When receiving a status changefrom the peer port,
163            pass it to the bridge. */
164        virtual void recvStatusChange(Status status);
165
166        /** When receiving a address range request the peer port,
167            pass it to the bridge. */
168        virtual void getDeviceAddressRanges(AddrRangeList &resp,
169                                            AddrRangeList &snoop);
170    };
171
172    BridgePort portA, portB;
173
174    /** If this bridge should acknowledge writes. */
175    bool ackWrites;
176
177  public:
178
179    /** A function used to return the port associated with this bus object. */
180    virtual Port *getPort(const std::string &if_name);
181
182    virtual void init();
183
184    Bridge(const std::string &n, int qsa, int qsb, Tick _delay, int write_ack);
185};
186
187#endif //__MEM_BUS_HH__
188