xbar.hh revision 3489 
1/*
2 * Copyright (c) 2002-2005 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: Ron Dreslinski
29 *          Ali Saidi
30 */
31
32/**
33 * @file
34 * Declaration of a bus object.
35 */
36
37#ifndef __MEM_BUS_HH__
38#define __MEM_BUS_HH__
39
40#include <string>
41#include <list>
42#include <inttypes.h>
43
44#include "base/range.hh"
45#include "mem/mem_object.hh"
46#include "mem/packet.hh"
47#include "mem/port.hh"
48#include "mem/request.hh"
49#include "sim/eventq.hh"
50
51class Bus : public MemObject
52{
53    /** a globally unique id for this bus. */
54    int busId;
55    /** the clock speed for the bus */
56    int clock;
57    /** the width of the bus in bytes */
58    int width;
59    /** the next tick at which the bus will be idle */
60    Tick tickNextIdle;
61
62    static const int defaultId = -3; //Make it unique from Broadcast
63
64    struct DevMap {
65        int portId;
66        Range<Addr> range;
67    };
68    std::vector<DevMap> portList;
69    AddrRangeList defaultRange;
70    std::vector<DevMap> portSnoopList;
71
72    /** Function called by the port when the bus is recieving a Timing
73      transaction.*/
74    bool recvTiming(PacketPtr pkt);
75
76    /** Function called by the port when the bus is recieving a Atomic
77      transaction.*/
78    Tick recvAtomic(PacketPtr pkt);
79
80    /** Function called by the port when the bus is recieving a Functional
81        transaction.*/
82    void recvFunctional(PacketPtr pkt);
83
84    /** Timing function called by port when it is once again able to process
85     * requests. */
86    void recvRetry(int id);
87
88    /** Function called by the port when the bus is recieving a status change.*/
89    void recvStatusChange(Port::Status status, int id);
90
91    /** Find which port connected to this bus (if any) should be given a packet
92     * with this address.
93     * @param addr Address to find port for.
94     * @param id Id of the port this packet was received from (to prevent
95     *             loops)
96     * @return pointer to port that the packet should be sent out of.
97     */
98    Port *findPort(Addr addr, int id);
99
100    /** Find all ports with a matching snoop range, except src port.  Keep in mind
101     * that the ranges shouldn't overlap or you will get a double snoop to the same
102     * interface.and the cache will assert out.
103     * @param addr Address to find snoop prts for.
104     * @param id Id of the src port of the request to avoid calling snoop on src
105     * @return vector of IDs to snoop on
106     */
107    std::vector<int> findSnoopPorts(Addr addr, int id);
108
109    /** Snoop all relevant ports atomicly. */
110    Tick atomicSnoop(PacketPtr pkt);
111
112    /** Snoop all relevant ports functionally. */
113    void functionalSnoop(PacketPtr pkt);
114
115    /** Call snoop on caches, be sure to set SNOOP_COMMIT bit if you want
116     * the snoop to happen
117     * @return True if succeds.
118     */
119    bool timingSnoop(PacketPtr pkt);
120
121    /** Process address range request.
122     * @param resp addresses that we can respond to
123     * @param snoop addresses that we would like to snoop
124     * @param id ide of the busport that made the request.
125     */
126    void addressRanges(AddrRangeList &resp, AddrRangeList &snoop, int id);
127
128    /** Occupy the bus with transmitting the packet pkt */
129    void occupyBus(PacketPtr pkt);
130
131    /** Declaration of the buses port type, one will be instantiated for each
132        of the interfaces connecting to the bus. */
133    class BusPort : public Port
134    {
135        bool _onRetryList;
136
137        /** A pointer to the bus to which this port belongs. */
138        Bus *bus;
139
140        /** A id to keep track of the intercafe ID this port is connected to. */
141        int id;
142
143      public:
144
145        /** Constructor for the BusPort.*/
146        BusPort(const std::string &_name, Bus *_bus, int _id)
147            : Port(_name, _bus), _onRetryList(false), bus(_bus), id(_id)
148        { }
149
150        bool onRetryList()
151        { return _onRetryList; }
152
153        void onRetryList(bool newVal)
154        { _onRetryList = newVal; }
155
156      protected:
157
158        /** When reciving a timing request from the peer port (at id),
159            pass it to the bus. */
160        virtual bool recvTiming(PacketPtr pkt)
161        { pkt->setSrc(id); return bus->recvTiming(pkt); }
162
163        /** When reciving a Atomic requestfrom the peer port (at id),
164            pass it to the bus. */
165        virtual Tick recvAtomic(PacketPtr pkt)
166        { pkt->setSrc(id); return bus->recvAtomic(pkt); }
167
168        /** When reciving a Functional requestfrom the peer port (at id),
169            pass it to the bus. */
170        virtual void recvFunctional(PacketPtr pkt)
171        { pkt->setSrc(id); bus->recvFunctional(pkt); }
172
173        /** When reciving a status changefrom the peer port (at id),
174            pass it to the bus. */
175        virtual void recvStatusChange(Status status)
176        { bus->recvStatusChange(status, id); }
177
178        /** When reciving a retry from the peer port (at id),
179            pass it to the bus. */
180        virtual void recvRetry()
181        { bus->recvRetry(id); }
182
183        // This should return all the 'owned' addresses that are
184        // downstream from this bus, yes?  That is, the union of all
185        // the 'owned' address ranges of all the other interfaces on
186        // this bus...
187        virtual void getDeviceAddressRanges(AddrRangeList &resp,
188                                            AddrRangeList &snoop)
189        { bus->addressRanges(resp, snoop, id); }
190
191        // Hack to make translating port work without changes
192        virtual int deviceBlockSize() { return 32; }
193
194    };
195
196    class BusFreeEvent : public Event
197    {
198        Bus * bus;
199
200      public:
201        BusFreeEvent(Bus * _bus);
202        void process();
203        const char *description();
204    };
205
206    BusFreeEvent busIdle;
207
208    bool inRetry;
209
210    /** An array of pointers to the peer port interfaces
211        connected to this bus.*/
212    std::vector<BusPort*> interfaces;
213
214    /** An array of pointers to ports that retry should be called on because the
215     * original send failed for whatever reason.*/
216    std::list<BusPort*> retryList;
217
218    void addToRetryList(BusPort * port)
219    {
220        if (!inRetry) {
221            // The device wasn't retrying a packet, or wasn't at an appropriate
222            // time.
223            assert(!port->onRetryList());
224            port->onRetryList(true);
225            retryList.push_back(port);
226        } else {
227            if (port->onRetryList()) {
228                // The device was retrying a packet. It didn't work, so we'll leave
229                // it at the head of the retry list.
230                assert(port == retryList.front());
231                inRetry = false;
232            }
233            else {
234                port->onRetryList(true);
235                retryList.push_back(port);
236            }
237        }
238    }
239
240    /** Port that handles requests that don't match any of the interfaces.*/
241    BusPort *defaultPort;
242
243    /** Has the user specified their own default responder? */
244    bool responderSet;
245
246  public:
247
248    /** A function used to return the port associated with this bus object. */
249    virtual Port *getPort(const std::string &if_name, int idx = -1);
250
251    virtual void init();
252
253    Bus(const std::string &n, int bus_id, int _clock, int _width,
254        bool responder_set)
255        : MemObject(n), busId(bus_id), clock(_clock), width(_width),
256          tickNextIdle(0), busIdle(this), inRetry(false), defaultPort(NULL),
257          responderSet(responder_set)
258    {
259        //Both the width and clock period must be positive
260        if (width <= 0)
261            fatal("Bus width must be positive\n");
262        if (clock <= 0)
263            fatal("Bus clock period must be positive\n");
264    }
265
266};
267
268#endif //__MEM_BUS_HH__
269