bridge.hh revision 4433:4722c6787f69 
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            bool nacked;
83
84            PacketBuffer(PacketPtr _pkt, Tick t, bool nack = false)
85                : ready(t), pkt(_pkt),
86                  origSenderState(_pkt->senderState), origSrc(_pkt->getSrc()),
87                  expectResponse(_pkt->needsResponse() && !nack),
88                  partialWriteFixed(false), nacked(nack)
89
90            {
91                if (!pkt->isResponse() && !nack)
92                    pkt->senderState = this;
93            }
94
95            void fixResponse(PacketPtr pkt)
96            {
97                assert(pkt->senderState == this);
98                pkt->setDest(origSrc);
99                pkt->senderState = origSenderState;
100                if (partialWriteFixed)
101                    delete oldPkt;
102            }
103
104            void partialWriteFix(Port *port)
105            {
106                assert(!partialWriteFixed);
107                assert(expectResponse);
108
109                int pbs = port->peerBlockSize();
110                partialWriteFixed = true;
111                PacketDataPtr data;
112
113                data = new uint8_t[pbs];
114                PacketPtr funcPkt = new Packet(pkt->req, MemCmd::ReadReq,
115                        Packet::Broadcast, pbs);
116
117                funcPkt->dataStatic(data);
118                port->sendFunctional(funcPkt);
119                assert(funcPkt->result == Packet::Success);
120                delete funcPkt;
121
122                oldPkt = pkt;
123                memcpy(data + oldPkt->getOffset(pbs), pkt->getPtr<uint8_t>(),
124                        pkt->getSize());
125                pkt = new Packet(oldPkt->req, MemCmd::WriteInvalidateReq,
126                        Packet::Broadcast, pbs);
127                pkt->dataDynamicArray(data);
128                pkt->senderState = oldPkt->senderState;
129            }
130
131            void undoPartialWriteFix()
132            {
133                if (!partialWriteFixed)
134                    return;
135                delete pkt;
136                pkt = oldPkt;
137                partialWriteFixed = false;
138            }
139
140        };
141
142        /**
143         * Outbound packet queue.  Packets are held in this queue for a
144         * specified delay to model the processing delay of the
145         * bridge.
146         */
147        std::list<PacketBuffer*> sendQueue;
148
149        int outstandingResponses;
150        int queuedRequests;
151
152        /** Max queue size for outbound packets */
153        int queueLimit;
154
155        /**
156         * Is this side blocked from accepting outbound packets?
157         */
158        bool queueFull();
159
160        void queueForSendTiming(PacketPtr pkt);
161
162        void finishSend(PacketBuffer *buf);
163
164        void nackRequest(PacketPtr pkt);
165
166        /**
167         * Handle send event, scheduled when the packet at the head of
168         * the outbound queue is ready to transmit (for timing
169         * accesses only).
170         */
171        void trySend();
172
173        class SendEvent : public Event
174        {
175            BridgePort *port;
176
177          public:
178            SendEvent(BridgePort *p)
179                : Event(&mainEventQueue), port(p) {}
180
181            virtual void process() { port->trySend(); }
182
183            virtual const char *description() { return "bridge send event"; }
184        };
185
186        SendEvent sendEvent;
187
188      public:
189
190        /** Constructor for the BusPort.*/
191        BridgePort(const std::string &_name,
192                   Bridge *_bridge, BridgePort *_otherPort,
193                   int _delay, int _queueLimit, bool fix_partial_write);
194
195      protected:
196
197        /** When receiving a timing request from the peer port,
198            pass it to the bridge. */
199        virtual bool recvTiming(PacketPtr pkt);
200
201        /** When receiving a retry request from the peer port,
202            pass it to the bridge. */
203        virtual void recvRetry();
204
205        /** When receiving a Atomic requestfrom the peer port,
206            pass it to the bridge. */
207        virtual Tick recvAtomic(PacketPtr pkt);
208
209        /** When receiving a Functional request from the peer port,
210            pass it to the bridge. */
211        virtual void recvFunctional(PacketPtr pkt);
212
213        /** When receiving a status changefrom the peer port,
214            pass it to the bridge. */
215        virtual void recvStatusChange(Status status);
216
217        /** When receiving a address range request the peer port,
218            pass it to the bridge. */
219        virtual void getDeviceAddressRanges(AddrRangeList &resp,
220                                            AddrRangeList &snoop);
221    };
222
223    BridgePort portA, portB;
224
225    /** If this bridge should acknowledge writes. */
226    bool ackWrites;
227
228  public:
229
230    /** A function used to return the port associated with this bus object. */
231    virtual Port *getPort(const std::string &if_name, int idx = -1);
232
233    virtual void init();
234
235    Bridge(const std::string &n, int qsa, int qsb, Tick _delay, int write_ack,
236            bool fix_partial_write_a, bool fix_partial_write_b);
237};
238
239#endif //__MEM_BUS_HH__
240