bridge.hh revision 4450:54dbcf524f0b 
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        /** Min delay to respond to a nack. */
70        Tick nackDelay;
71
72        bool fixPartialWrite;
73
74        class PacketBuffer : public Packet::SenderState {
75
76          public:
77            Tick ready;
78            PacketPtr pkt;
79            Packet::SenderState *origSenderState;
80            short origSrc;
81            bool expectResponse;
82
83            bool partialWriteFixed;
84            PacketPtr oldPkt;
85
86            PacketBuffer(PacketPtr _pkt, Tick t, bool nack = false)
87                : ready(t), pkt(_pkt),
88                  origSenderState(_pkt->senderState), origSrc(_pkt->getSrc()),
89                  expectResponse(_pkt->needsResponse() && !nack),
90                  partialWriteFixed(false)
91
92            {
93                if (!pkt->isResponse() && !nack && pkt->result != Packet::Nacked)
94                    pkt->senderState = this;
95            }
96
97            void fixResponse(PacketPtr pkt)
98            {
99                assert(pkt->senderState == this);
100                pkt->setDest(origSrc);
101                pkt->senderState = origSenderState;
102                if (partialWriteFixed)
103                    delete oldPkt;
104            }
105
106            void partialWriteFix(Port *port)
107            {
108                assert(!partialWriteFixed);
109                assert(expectResponse);
110
111                int pbs = port->peerBlockSize();
112                partialWriteFixed = true;
113                PacketDataPtr data;
114
115                data = new uint8_t[pbs];
116                PacketPtr funcPkt = new Packet(pkt->req, MemCmd::ReadReq,
117                        Packet::Broadcast, pbs);
118
119                funcPkt->dataStatic(data);
120                port->sendFunctional(funcPkt);
121                assert(funcPkt->result == Packet::Success);
122                delete funcPkt;
123
124                oldPkt = pkt;
125                memcpy(data + oldPkt->getOffset(pbs), pkt->getPtr<uint8_t>(),
126                        pkt->getSize());
127                pkt = new Packet(oldPkt->req, MemCmd::WriteInvalidateReq,
128                        Packet::Broadcast, pbs);
129                pkt->dataDynamicArray(data);
130                pkt->senderState = oldPkt->senderState;
131            }
132
133            void undoPartialWriteFix()
134            {
135                if (!partialWriteFixed)
136                    return;
137                delete pkt;
138                pkt = oldPkt;
139                partialWriteFixed = false;
140            }
141
142        };
143
144        /**
145         * Outbound packet queue.  Packets are held in this queue for a
146         * specified delay to model the processing delay of the
147         * bridge.
148         */
149        std::list<PacketBuffer*> sendQueue;
150
151        int outstandingResponses;
152        int queuedRequests;
153
154        /** If we're waiting for a retry to happen.*/
155        bool inRetry;
156
157        /** Max queue size for outbound packets */
158        int reqQueueLimit;
159
160        /** Max queue size for reserved responses. */
161        int respQueueLimit;
162
163        /**
164         * Is this side blocked from accepting outbound packets?
165         */
166        bool respQueueFull();
167        bool reqQueueFull();
168
169        void queueForSendTiming(PacketPtr pkt);
170
171        void finishSend(PacketBuffer *buf);
172
173        void nackRequest(PacketPtr pkt);
174
175        /**
176         * Handle send event, scheduled when the packet at the head of
177         * the outbound queue is ready to transmit (for timing
178         * accesses only).
179         */
180        void trySend();
181
182        class SendEvent : public Event
183        {
184            BridgePort *port;
185
186          public:
187            SendEvent(BridgePort *p)
188                : Event(&mainEventQueue), port(p) {}
189
190            virtual void process() { port->trySend(); }
191
192            virtual const char *description() { return "bridge send event"; }
193        };
194
195        SendEvent sendEvent;
196
197      public:
198        /** Constructor for the BusPort.*/
199        BridgePort(const std::string &_name, Bridge *_bridge,
200                BridgePort *_otherPort, int _delay, int _nack_delay,
201                int _req_limit, int _resp_limit, bool fix_partial_write);
202
203      protected:
204
205        /** When receiving a timing request from the peer port,
206            pass it to the bridge. */
207        virtual bool recvTiming(PacketPtr pkt);
208
209        /** When receiving a retry request from the peer port,
210            pass it to the bridge. */
211        virtual void recvRetry();
212
213        /** When receiving a Atomic requestfrom the peer port,
214            pass it to the bridge. */
215        virtual Tick recvAtomic(PacketPtr pkt);
216
217        /** When receiving a Functional request from the peer port,
218            pass it to the bridge. */
219        virtual void recvFunctional(PacketPtr pkt);
220
221        /** When receiving a status changefrom the peer port,
222            pass it to the bridge. */
223        virtual void recvStatusChange(Status status);
224
225        /** When receiving a address range request the peer port,
226            pass it to the bridge. */
227        virtual void getDeviceAddressRanges(AddrRangeList &resp,
228                                            AddrRangeList &snoop);
229    };
230
231    BridgePort portA, portB;
232
233    /** If this bridge should acknowledge writes. */
234    bool ackWrites;
235
236  public:
237    struct Params
238    {
239        std::string name;
240        int req_size_a;
241        int req_size_b;
242        int resp_size_a;
243        int resp_size_b;
244        Tick delay;
245        Tick nack_delay;
246        bool write_ack;
247        bool fix_partial_write_a;
248        bool fix_partial_write_b;
249    };
250
251  protected:
252    Params *_params;
253
254  public:
255    const Params *params() const { return _params; }
256
257    /** A function used to return the port associated with this bus object. */
258    virtual Port *getPort(const std::string &if_name, int idx = -1);
259
260    virtual void init();
261
262    Bridge(Params *p);
263};
264
265#endif //__MEM_BUS_HH__
266