bridge.hh revision 3349:fec4a86fa212 
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 "mem/mem_object.hh"
46#include "mem/packet.hh"
47#include "mem/port.hh"
48#include "sim/eventq.hh"
49
50class Bridge : public MemObject
51{
52  protected:
53    /** Declaration of the buses port type, one will be instantiated for each
54        of the interfaces connecting to the bus. */
55    class BridgePort : public Port
56    {
57        /** A pointer to the bridge to which this port belongs. */
58        Bridge *bridge;
59
60        /**
61         * Pointer to the port on the other side of the bridge
62         * (connected to the other bus).
63         */
64        BridgePort *otherPort;
65
66        /** Minimum delay though this bridge. */
67        Tick delay;
68
69        class PacketBuffer : public Packet::SenderState {
70
71          public:
72            Tick ready;
73            PacketPtr pkt;
74            Packet::SenderState *origSenderState;
75            short origSrc;
76            bool expectResponse;
77
78            PacketBuffer(PacketPtr _pkt, Tick t)
79                : ready(t), pkt(_pkt),
80                  origSenderState(_pkt->senderState), origSrc(_pkt->getSrc()),
81                  expectResponse(_pkt->needsResponse())
82            {
83                if (!pkt->isResponse())
84                    pkt->senderState = this;
85            }
86
87            void fixResponse(PacketPtr pkt)
88            {
89                assert(pkt->senderState == this);
90                pkt->setDest(origSrc);
91                pkt->senderState = origSenderState;
92            }
93        };
94
95        /**
96         * Outbound packet queue.  Packets are held in this queue for a
97         * specified delay to model the processing delay of the
98         * bridge.
99         */
100        std::list<PacketBuffer*> sendQueue;
101
102        int outstandingResponses;
103
104        /** Max queue size for outbound packets */
105        int queueLimit;
106
107        /**
108         * Is this side blocked from accepting outbound packets?
109         */
110        bool queueFull() { return (sendQueue.size() == queueLimit); }
111
112        bool queueForSendTiming(PacketPtr pkt);
113
114        void finishSend(PacketBuffer *buf);
115
116        /**
117         * Handle send event, scheduled when the packet at the head of
118         * the outbound queue is ready to transmit (for timing
119         * accesses only).
120         */
121        void trySend();
122
123        class SendEvent : public Event
124        {
125            BridgePort *port;
126
127          public:
128            SendEvent(BridgePort *p)
129                : Event(&mainEventQueue), port(p) {}
130
131            virtual void process() { port->trySend(); }
132
133            virtual const char *description() { return "bridge send event"; }
134        };
135
136        SendEvent sendEvent;
137
138      public:
139
140        /** Constructor for the BusPort.*/
141        BridgePort(const std::string &_name,
142                   Bridge *_bridge, BridgePort *_otherPort,
143                   int _delay, int _queueLimit);
144
145      protected:
146
147        /** When receiving a timing request from the peer port,
148            pass it to the bridge. */
149        virtual bool recvTiming(PacketPtr pkt);
150
151        /** When receiving a retry request from the peer port,
152            pass it to the bridge. */
153        virtual void recvRetry();
154
155        /** When receiving a Atomic requestfrom the peer port,
156            pass it to the bridge. */
157        virtual Tick recvAtomic(PacketPtr pkt);
158
159        /** When receiving a Functional request from the peer port,
160            pass it to the bridge. */
161        virtual void recvFunctional(PacketPtr pkt);
162
163        /** When receiving a status changefrom the peer port,
164            pass it to the bridge. */
165        virtual void recvStatusChange(Status status);
166
167        /** When receiving a address range request the peer port,
168            pass it to the bridge. */
169        virtual void getDeviceAddressRanges(AddrRangeList &resp,
170                                            AddrRangeList &snoop);
171    };
172
173    BridgePort portA, portB;
174
175    /** If this bridge should acknowledge writes. */
176    bool ackWrites;
177
178  public:
179
180    /** A function used to return the port associated with this bus object. */
181    virtual Port *getPort(const std::string &if_name, int idx = -1);
182
183    virtual void init();
184
185    Bridge(const std::string &n, int qsa, int qsb, Tick _delay, int write_ack);
186};
187
188#endif //__MEM_BUS_HH__
189