bridge.hh revision 4432 
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        bool fixPartialWrite;
70
71        class PacketBuffer : public Packet::SenderState {
72
73          public:
74            Tick ready;
75            PacketPtr pkt;
76            Packet::SenderState *origSenderState;
77            short origSrc;
78            bool expectResponse;
79
80            bool partialWriteFixed;
81            PacketPtr oldPkt;
82
83            PacketBuffer(PacketPtr _pkt, Tick t)
84                : ready(t), pkt(_pkt),
85                  origSenderState(_pkt->senderState), origSrc(_pkt->getSrc()),
86                  expectResponse(_pkt->needsResponse()), partialWriteFixed(false)
87            {
88                if (!pkt->isResponse())
89                    pkt->senderState = this;
90            }
91
92            void fixResponse(PacketPtr pkt)
93            {
94                assert(pkt->senderState == this);
95                pkt->setDest(origSrc);
96                pkt->senderState = origSenderState;
97                if (partialWriteFixed)
98                    delete oldPkt;
99            }
100
101            void partialWriteFix(Port *port)
102            {
103                assert(!partialWriteFixed);
104                assert(expectResponse);
105
106                int pbs = port->peerBlockSize();
107                partialWriteFixed = true;
108                PacketDataPtr data;
109
110                data = new uint8_t[pbs];
111                PacketPtr funcPkt = new Packet(pkt->req, MemCmd::ReadReq,
112                        Packet::Broadcast, pbs);
113
114                funcPkt->dataStatic(data);
115                port->sendFunctional(funcPkt);
116                assert(funcPkt->result == Packet::Success);
117                delete funcPkt;
118
119                oldPkt = pkt;
120                memcpy(data + oldPkt->getOffset(pbs), pkt->getPtr<uint8_t>(),
121                        pkt->getSize());
122                pkt = new Packet(oldPkt->req, MemCmd::WriteInvalidateReq,
123                        Packet::Broadcast, pbs);
124                pkt->dataDynamicArray(data);
125                pkt->senderState = oldPkt->senderState;
126            }
127
128            void undoPartialWriteFix()
129            {
130                if (!partialWriteFixed)
131                    return;
132                delete pkt;
133                pkt = oldPkt;
134                partialWriteFixed = false;
135            }
136
137        };
138
139        /**
140         * Outbound packet queue.  Packets are held in this queue for a
141         * specified delay to model the processing delay of the
142         * bridge.
143         */
144        std::list<PacketBuffer*> sendQueue;
145
146        int outstandingResponses;
147
148        /** Max queue size for outbound packets */
149        int queueLimit;
150
151        /**
152         * Is this side blocked from accepting outbound packets?
153         */
154        bool queueFull() { return (sendQueue.size() == queueLimit); }
155
156        bool queueForSendTiming(PacketPtr pkt);
157
158        void finishSend(PacketBuffer *buf);
159
160        /**
161         * Handle send event, scheduled when the packet at the head of
162         * the outbound queue is ready to transmit (for timing
163         * accesses only).
164         */
165        void trySend();
166
167        class SendEvent : public Event
168        {
169            BridgePort *port;
170
171          public:
172            SendEvent(BridgePort *p)
173                : Event(&mainEventQueue), port(p) {}
174
175            virtual void process() { port->trySend(); }
176
177            virtual const char *description() { return "bridge send event"; }
178        };
179
180        SendEvent sendEvent;
181
182      public:
183
184        /** Constructor for the BusPort.*/
185        BridgePort(const std::string &_name,
186                   Bridge *_bridge, BridgePort *_otherPort,
187                   int _delay, int _queueLimit, bool fix_partial_write);
188
189      protected:
190
191        /** When receiving a timing request from the peer port,
192            pass it to the bridge. */
193        virtual bool recvTiming(PacketPtr pkt);
194
195        /** When receiving a retry request from the peer port,
196            pass it to the bridge. */
197        virtual void recvRetry();
198
199        /** When receiving a Atomic requestfrom the peer port,
200            pass it to the bridge. */
201        virtual Tick recvAtomic(PacketPtr pkt);
202
203        /** When receiving a Functional request from the peer port,
204            pass it to the bridge. */
205        virtual void recvFunctional(PacketPtr pkt);
206
207        /** When receiving a status changefrom the peer port,
208            pass it to the bridge. */
209        virtual void recvStatusChange(Status status);
210
211        /** When receiving a address range request the peer port,
212            pass it to the bridge. */
213        virtual void getDeviceAddressRanges(AddrRangeList &resp,
214                                            AddrRangeList &snoop);
215    };
216
217    BridgePort portA, portB;
218
219    /** If this bridge should acknowledge writes. */
220    bool ackWrites;
221
222  public:
223
224    /** A function used to return the port associated with this bus object. */
225    virtual Port *getPort(const std::string &if_name, int idx = -1);
226
227    virtual void init();
228
229    Bridge(const std::string &n, int qsa, int qsb, Tick _delay, int write_ack,
230            bool fix_partial_write_a, bool fix_partial_write_b);
231};
232
233#endif //__MEM_BUS_HH__
234