bridge.hh revision 4451:bfb7c7c0b7ea 
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                Addr pbs = port->peerBlockSize();
112                Addr blockAddr = pkt->getAddr() & ~(pbs-1);
113                partialWriteFixed = true;
114                PacketDataPtr data;
115
116                data = new uint8_t[pbs];
117                RequestPtr funcReq = new Request(blockAddr, 4, 0);
118                PacketPtr funcPkt = new Packet(funcReq, MemCmd::ReadReq,
119                            Packet::Broadcast);
120                for (int x = 0; x < pbs; x+=4) {
121                    funcReq->setPhys(blockAddr + x, 4, 0);
122                    funcPkt->reinitFromRequest();
123                    funcPkt->dataStatic(data + x);
124                    port->sendFunctional(funcPkt);
125                    assert(funcPkt->result == Packet::Success);
126                }
127                delete funcPkt;
128                delete funcReq;
129
130                oldPkt = pkt;
131                memcpy(data + oldPkt->getOffset(pbs), pkt->getPtr<uint8_t>(),
132                        pkt->getSize());
133                pkt = new Packet(oldPkt->req, MemCmd::WriteInvalidateReq,
134                        Packet::Broadcast, pbs);
135                pkt->dataDynamicArray(data);
136                pkt->senderState = oldPkt->senderState;
137            }
138
139            void undoPartialWriteFix()
140            {
141                if (!partialWriteFixed)
142                    return;
143                delete pkt;
144                pkt = oldPkt;
145                partialWriteFixed = false;
146            }
147
148        };
149
150        /**
151         * Outbound packet queue.  Packets are held in this queue for a
152         * specified delay to model the processing delay of the
153         * bridge.
154         */
155        std::list<PacketBuffer*> sendQueue;
156
157        int outstandingResponses;
158        int queuedRequests;
159
160        /** If we're waiting for a retry to happen.*/
161        bool inRetry;
162
163        /** Max queue size for outbound packets */
164        int reqQueueLimit;
165
166        /** Max queue size for reserved responses. */
167        int respQueueLimit;
168
169        /**
170         * Is this side blocked from accepting outbound packets?
171         */
172        bool respQueueFull();
173        bool reqQueueFull();
174
175        void queueForSendTiming(PacketPtr pkt);
176
177        void finishSend(PacketBuffer *buf);
178
179        void nackRequest(PacketPtr pkt);
180
181        /**
182         * Handle send event, scheduled when the packet at the head of
183         * the outbound queue is ready to transmit (for timing
184         * accesses only).
185         */
186        void trySend();
187
188        class SendEvent : public Event
189        {
190            BridgePort *port;
191
192          public:
193            SendEvent(BridgePort *p)
194                : Event(&mainEventQueue), port(p) {}
195
196            virtual void process() { port->trySend(); }
197
198            virtual const char *description() { return "bridge send event"; }
199        };
200
201        SendEvent sendEvent;
202
203      public:
204        /** Constructor for the BusPort.*/
205        BridgePort(const std::string &_name, Bridge *_bridge,
206                BridgePort *_otherPort, int _delay, int _nack_delay,
207                int _req_limit, int _resp_limit, bool fix_partial_write);
208
209      protected:
210
211        /** When receiving a timing request from the peer port,
212            pass it to the bridge. */
213        virtual bool recvTiming(PacketPtr pkt);
214
215        /** When receiving a retry request from the peer port,
216            pass it to the bridge. */
217        virtual void recvRetry();
218
219        /** When receiving a Atomic requestfrom the peer port,
220            pass it to the bridge. */
221        virtual Tick recvAtomic(PacketPtr pkt);
222
223        /** When receiving a Functional request from the peer port,
224            pass it to the bridge. */
225        virtual void recvFunctional(PacketPtr pkt);
226
227        /** When receiving a status changefrom the peer port,
228            pass it to the bridge. */
229        virtual void recvStatusChange(Status status);
230
231        /** When receiving a address range request the peer port,
232            pass it to the bridge. */
233        virtual void getDeviceAddressRanges(AddrRangeList &resp,
234                                            AddrRangeList &snoop);
235    };
236
237    BridgePort portA, portB;
238
239    /** If this bridge should acknowledge writes. */
240    bool ackWrites;
241
242  public:
243    struct Params
244    {
245        std::string name;
246        int req_size_a;
247        int req_size_b;
248        int resp_size_a;
249        int resp_size_b;
250        Tick delay;
251        Tick nack_delay;
252        bool write_ack;
253        bool fix_partial_write_a;
254        bool fix_partial_write_b;
255    };
256
257  protected:
258    Params *_params;
259
260  public:
261    const Params *params() const { return _params; }
262
263    /** A function used to return the port associated with this bus object. */
264    virtual Port *getPort(const std::string &if_name, int idx = -1);
265
266    virtual void init();
267
268    Bridge(Params *p);
269};
270
271#endif //__MEM_BUS_HH__
272