bridge.hh revision 2657:b119b774656b 
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
29/**
30 * @file Decleration of a simple bus bridge object with no buffering
31 */
32
33#ifndef __MEM_BRIDGE_HH__
34#define __MEM_BRIDGE_HH__
35
36#include <string>
37#include <list>
38#include <inttypes.h>
39#include <queue>
40
41#include "mem/mem_object.hh"
42#include "mem/packet.hh"
43#include "mem/port.hh"
44#include "sim/eventq.hh"
45
46class Bridge : public MemObject
47{
48  protected:
49    /** Decleration of the buses port type, one will be instantiated for each
50        of the interfaces connecting to the bus. */
51    class BridgePort : public Port
52    {
53        /** A pointer to the bridge to which this port belongs. */
54        Bridge *bridge;
55
56        /**
57         * Pointer to the port on the other side of the bridge
58         * (connected to the other bus).
59         */
60        BridgePort *otherPort;
61
62        /** Minimum delay though this bridge. */
63        Tick delay;
64
65        class PacketBuffer : public Packet::SenderState {
66
67          public:
68            Tick ready;
69            Packet *pkt;
70            Packet::SenderState *origSenderState;
71            short origSrc;
72            bool expectResponse;
73
74            PacketBuffer(Packet *_pkt, Tick t)
75                : ready(t), pkt(_pkt),
76                  origSenderState(_pkt->senderState), origSrc(_pkt->getSrc()),
77                  expectResponse(_pkt->needsResponse())
78            {
79                if (!pkt->isResponse())
80                    pkt->senderState = this;
81            }
82
83            void fixResponse(Packet *pkt)
84            {
85                assert(pkt->senderState == this);
86                pkt->setDest(origSrc);
87                pkt->senderState = origSenderState;
88            }
89        };
90
91        /**
92         * Outbound packet queue.  Packets are held in this queue for a
93         * specified delay to model the processing delay of the
94         * bridge.
95         */
96        std::list<PacketBuffer*> sendQueue;
97
98        int outstandingResponses;
99
100        /** Max queue size for outbound packets */
101        int queueLimit;
102
103        /**
104         * Is this side blocked from accepting outbound packets?
105         */
106        bool queueFull() { return (sendQueue.size() == queueLimit); }
107
108        bool queueForSendTiming(Packet *pkt);
109
110        void finishSend(PacketBuffer *buf);
111
112        /**
113         * Handle send event, scheduled when the packet at the head of
114         * the outbound queue is ready to transmit (for timing
115         * accesses only).
116         */
117        void trySend();
118
119        class SendEvent : public Event
120        {
121            BridgePort *port;
122
123          public:
124            SendEvent(BridgePort *p)
125                : Event(&mainEventQueue), port(p) {}
126
127            virtual void process() { port->trySend(); }
128
129            virtual const char *description() { return "bridge send event"; }
130        };
131
132        SendEvent sendEvent;
133
134      public:
135
136        /** Constructor for the BusPort.*/
137        BridgePort(const std::string &_name,
138                   Bridge *_bridge, BridgePort *_otherPort,
139                   int _delay, int _queueLimit);
140
141      protected:
142
143        /** When receiving a timing request from the peer port,
144            pass it to the bridge. */
145        virtual bool recvTiming(Packet *pkt);
146
147        /** When receiving a retry request from the peer port,
148            pass it to the bridge. */
149        virtual void recvRetry();
150
151        /** When receiving a Atomic requestfrom the peer port,
152            pass it to the bridge. */
153        virtual Tick recvAtomic(Packet *pkt);
154
155        /** When receiving a Functional request from the peer port,
156            pass it to the bridge. */
157        virtual void recvFunctional(Packet *pkt);
158
159        /** When receiving a status changefrom the peer port,
160            pass it to the bridge. */
161        virtual void recvStatusChange(Status status);
162
163        /** When receiving a address range request the peer port,
164            pass it to the bridge. */
165        virtual void getDeviceAddressRanges(AddrRangeList &resp,
166                                            AddrRangeList &snoop);
167    };
168
169    BridgePort portA, portB;
170
171    /** If this bridge should acknowledge writes. */
172    bool ackWrites;
173
174  public:
175
176    /** A function used to return the port associated with this bus object. */
177    virtual Port *getPort(const std::string &if_name);
178
179    virtual void init();
180
181    Bridge(const std::string &n, int qsa, int qsb, Tick _delay, int write_ack);
182};
183
184#endif //__MEM_BUS_HH__
185