noncoherent_xbar.hh revision 8922 
1/*
2 * Copyright (c) 2011 ARM Limited
3 * All rights reserved
4 *
5 * The license below extends only to copyright in the software and shall
6 * not be construed as granting a license to any other intellectual
7 * property including but not limited to intellectual property relating
8 * to a hardware implementation of the functionality of the software
9 * licensed hereunder.  You may use the software subject to the license
10 * terms below provided that you ensure that this notice is replicated
11 * unmodified and in its entirety in all distributions of the software,
12 * modified or unmodified, in source code or in binary form.
13 *
14 * Copyright (c) 2002-2005 The Regents of The University of Michigan
15 * All rights reserved.
16 *
17 * Redistribution and use in source and binary forms, with or without
18 * modification, are permitted provided that the following conditions are
19 * met: redistributions of source code must retain the above copyright
20 * notice, this list of conditions and the following disclaimer;
21 * redistributions in binary form must reproduce the above copyright
22 * notice, this list of conditions and the following disclaimer in the
23 * documentation and/or other materials provided with the distribution;
24 * neither the name of the copyright holders nor the names of its
25 * contributors may be used to endorse or promote products derived from
26 * this software without specific prior written permission.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
29 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
30 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
31 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
32 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
33 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
34 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
35 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
36 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
37 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
38 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
39 *
40 * Authors: Ron Dreslinski
41 *          Ali Saidi
42 *          Andreas Hansson
43 *          William Wang
44 */
45
46/**
47 * @file
48 * Declaration of a bus object.
49 */
50
51#ifndef __MEM_BUS_HH__
52#define __MEM_BUS_HH__
53
54#include <list>
55#include <set>
56#include <string>
57
58#include "base/range.hh"
59#include "base/range_map.hh"
60#include "base/types.hh"
61#include "mem/mem_object.hh"
62#include "mem/packet.hh"
63#include "mem/port.hh"
64#include "params/Bus.hh"
65#include "sim/eventq.hh"
66
67class Bus : public MemObject
68{
69    /**
70     * Declaration of the bus slave port type, one will be
71     * instantiated for each of the master interfaces connecting to
72     * the bus.
73     */
74    class BusSlavePort : public SlavePort
75    {
76      private:
77        /** A pointer to the bus to which this port belongs. */
78        Bus *bus;
79
80        /** A id to keep track of the interface ID of this port. */
81        int id;
82
83      public:
84
85        /** Constructor for the BusSlavePort.*/
86        BusSlavePort(const std::string &_name, Bus *_bus, int _id)
87            : SlavePort(_name, _bus), bus(_bus), id(_id)
88        { }
89
90        int getId() const { return id; }
91
92      protected:
93
94        /** When reciving a timing request from the peer port (at id),
95            pass it to the bus. */
96        virtual bool recvTiming(PacketPtr pkt)
97        { pkt->setSrc(id); return bus->recvTiming(pkt); }
98
99        /** When reciving a Atomic requestfrom the peer port (at id),
100            pass it to the bus. */
101        virtual Tick recvAtomic(PacketPtr pkt)
102        { pkt->setSrc(id); return bus->recvAtomic(pkt); }
103
104        /** When reciving a Functional requestfrom the peer port (at id),
105            pass it to the bus. */
106        virtual void recvFunctional(PacketPtr pkt)
107        { pkt->setSrc(id); bus->recvFunctional(pkt); }
108
109        /** When reciving a retry from the peer port (at id),
110            pass it to the bus. */
111        virtual void recvRetry()
112        { bus->recvRetry(id); }
113
114        // This should return all the 'owned' addresses that are
115        // downstream from this bus, yes?  That is, the union of all
116        // the 'owned' address ranges of all the other interfaces on
117        // this bus...
118        virtual AddrRangeList getAddrRanges()
119        { return bus->getAddrRanges(id); }
120
121        // Ask the bus to ask everyone on the bus what their block size is and
122        // take the max of it. This might need to be changed a bit if we ever
123        // support multiple block sizes.
124        virtual unsigned deviceBlockSize() const
125        { return bus->findBlockSize(id); }
126
127    };
128
129    /**
130     * Declaration of the bus master port type, one will be
131     * instantiated for each of the slave interfaces connecting to the
132     * bus.
133     */
134    class BusMasterPort : public MasterPort
135    {
136      private:
137        /** A pointer to the bus to which this port belongs. */
138        Bus *bus;
139
140        /** A id to keep track of the interface ID of this port. */
141        int id;
142
143      public:
144
145        /** Constructor for the BusMasterPort.*/
146        BusMasterPort(const std::string &_name, Bus *_bus, int _id)
147            : MasterPort(_name, _bus), bus(_bus), id(_id)
148        { }
149
150        int getId() const { return id; }
151
152        /**
153         * Determine if this port should be considered a snooper. This
154         * is determined by the bus.
155         *
156         * @return a boolean that is true if this port is snooping
157         */
158        virtual bool isSnooping() const
159        { return bus->isSnooping(id); }
160
161      protected:
162
163        /** When reciving a timing request from the peer port (at id),
164            pass it to the bus. */
165        virtual bool recvTiming(PacketPtr pkt)
166        { pkt->setSrc(id); return bus->recvTiming(pkt); }
167
168        /** When reciving a Atomic requestfrom the peer port (at id),
169            pass it to the bus. */
170        virtual Tick recvAtomic(PacketPtr pkt)
171        { pkt->setSrc(id); return bus->recvAtomic(pkt); }
172
173        /** When reciving a Functional requestfrom the peer port (at id),
174            pass it to the bus. */
175        virtual void recvFunctional(PacketPtr pkt)
176        { pkt->setSrc(id); bus->recvFunctional(pkt); }
177
178        /** When reciving a range change from the peer port (at id),
179            pass it to the bus. */
180        virtual void recvRangeChange()
181        { bus->recvRangeChange(id); }
182
183        /** When reciving a retry from the peer port (at id),
184            pass it to the bus. */
185        virtual void recvRetry()
186        { bus->recvRetry(id); }
187
188        // Ask the bus to ask everyone on the bus what their block size is and
189        // take the max of it. This might need to be changed a bit if we ever
190        // support multiple block sizes.
191        virtual unsigned deviceBlockSize() const
192        { return bus->findBlockSize(id); }
193
194    };
195
196    /** the clock speed for the bus */
197    int clock;
198    /** cycles of overhead per transaction */
199    int headerCycles;
200    /** the width of the bus in bytes */
201    int width;
202    /** the next tick at which the bus will be idle */
203    Tick tickNextIdle;
204
205    Event * drainEvent;
206
207    typedef range_map<Addr,int>::iterator PortIter;
208    range_map<Addr, int> portMap;
209
210    AddrRangeList defaultRange;
211
212    typedef std::vector<BusSlavePort*>::iterator SnoopIter;
213    std::vector<BusSlavePort*> snoopPorts;
214
215    /** Function called by the port when the bus is recieving a Timing
216      transaction.*/
217    bool recvTiming(PacketPtr pkt);
218
219    /** Function called by the port when the bus is recieving a Atomic
220      transaction.*/
221    Tick recvAtomic(PacketPtr pkt);
222
223    /** Function called by the port when the bus is recieving a Functional
224        transaction.*/
225    void recvFunctional(PacketPtr pkt);
226
227    /** Timing function called by port when it is once again able to process
228     * requests. */
229    void recvRetry(int id);
230
231    /** Function called by the port when the bus is recieving a range change.*/
232    void recvRangeChange(int id);
233
234    /** Find which port connected to this bus (if any) should be given a packet
235     * with this address.
236     * @param addr Address to find port for.
237     * @return id of port that the packet should be sent out of.
238     */
239    int findPort(Addr addr);
240
241    // Cache for the findPort function storing recently used ports from portMap
242    struct PortCache {
243        bool valid;
244        int  id;
245        Addr start;
246        Addr end;
247    };
248
249    PortCache portCache[3];
250
251    // Checks the cache and returns the id of the port that has the requested
252    // address within its range
253    inline int checkPortCache(Addr addr) {
254        if (portCache[0].valid && addr >= portCache[0].start &&
255            addr < portCache[0].end) {
256            return portCache[0].id;
257        }
258        if (portCache[1].valid && addr >= portCache[1].start &&
259                   addr < portCache[1].end) {
260            return portCache[1].id;
261        }
262        if (portCache[2].valid && addr >= portCache[2].start &&
263            addr < portCache[2].end) {
264            return portCache[2].id;
265        }
266
267        return INVALID_PORT_ID;
268    }
269
270    // Clears the earliest entry of the cache and inserts a new port entry
271    inline void updatePortCache(short id, Addr start, Addr end) {
272        portCache[2].valid = portCache[1].valid;
273        portCache[2].id    = portCache[1].id;
274        portCache[2].start = portCache[1].start;
275        portCache[2].end   = portCache[1].end;
276
277        portCache[1].valid = portCache[0].valid;
278        portCache[1].id    = portCache[0].id;
279        portCache[1].start = portCache[0].start;
280        portCache[1].end   = portCache[0].end;
281
282        portCache[0].valid = true;
283        portCache[0].id    = id;
284        portCache[0].start = start;
285        portCache[0].end   = end;
286    }
287
288    // Clears the cache. Needs to be called in constructor.
289    inline void clearPortCache() {
290        portCache[2].valid = false;
291        portCache[1].valid = false;
292        portCache[0].valid = false;
293    }
294
295    /**
296     * Return the address ranges this port is responsible for.
297     *
298     * @param id id of the bus port that made the request
299     *
300     * @return a list of non-overlapping address ranges
301     */
302    AddrRangeList getAddrRanges(int id);
303
304    /**
305     * Determine if the bus port is snooping or not.
306     *
307     * @param id id of the bus port that made the request
308     *
309     * @return a boolean indicating if this port is snooping or not
310     */
311    bool isSnooping(int id) const;
312
313    /** Calculate the timing parameters for the packet.  Updates the
314     * firstWordTime and finishTime fields of the packet object.
315     * Returns the tick at which the packet header is completed (which
316     * will be all that is sent if the target rejects the packet).
317     */
318    Tick calcPacketTiming(PacketPtr pkt);
319
320    /** Occupy the bus until until */
321    void occupyBus(Tick until);
322
323    /**
324     * Release the bus after being occupied and return to an idle
325     * state where we proceed to send a retry to any potential waiting
326     * port, or drain if asked to do so.
327     */
328    void releaseBus();
329
330    /**
331     * Send a retry to the port at the head of the retryList. The
332     * caller must ensure that the list is not empty.
333     */
334    void retryWaiting();
335
336    /** Ask everyone on the bus what their size is
337     * @param id id of the busport that made the request
338     * @return the max of all the sizes
339     */
340    unsigned findBlockSize(int id);
341
342    // event used to schedule a release of the bus
343    EventWrapper<Bus, &Bus::releaseBus> busIdleEvent;
344
345    bool inRetry;
346    std::set<int> inRecvRangeChange;
347
348    // keep track of the number of master ports (not counting the
349    // default master) since we need this as an offset into the
350    // interfaces vector
351    unsigned int nbrMasterPorts;
352
353    /** The master and slave ports of the bus */
354    std::vector<BusSlavePort*> slavePorts;
355    std::vector<BusMasterPort*> masterPorts;
356
357    /** An array of pointers to ports that retry should be called on because the
358     * original send failed for whatever reason.*/
359    std::list<Port*> retryList;
360
361    void addToRetryList(Port* port)
362    {
363        if (!inRetry) {
364            // The device wasn't retrying a packet, or wasn't at an
365            // appropriate time.
366            retryList.push_back(port);
367        } else {
368            if (!retryList.empty() && port == retryList.front()) {
369                // The device was retrying a packet. It didn't work,
370                // so we'll leave it at the head of the retry list.
371                inRetry = false;
372            } else {
373                // We are in retry, but not for this port, put it at
374                // the end.
375                retryList.push_back(port);
376            }
377        }
378    }
379
380    /** Port that handles requests that don't match any of the interfaces.*/
381    short defaultPortId;
382
383    /** A symbolic name for a port id that denotes no port. */
384    static const short INVALID_PORT_ID = -1;
385
386    /** If true, use address range provided by default device.  Any
387       address not handled by another port and not in default device's
388       range will cause a fatal error.  If false, just send all
389       addresses not handled by another port to default device. */
390    bool useDefaultRange;
391
392    unsigned defaultBlockSize;
393    unsigned cachedBlockSize;
394    bool cachedBlockSizeValid;
395
396  public:
397
398    /** A function used to return the port associated with this bus object. */
399    virtual MasterPort& getMasterPort(const std::string& if_name, int idx = -1);
400    virtual SlavePort& getSlavePort(const std::string& if_name, int idx = -1);
401
402    virtual void init();
403    virtual void startup();
404
405    unsigned int drain(Event *de);
406
407    Bus(const BusParams *p);
408};
409
410#endif //__MEM_BUS_HH__
411