coherent_xbar.hh revision 9090 
1/*
2 * Copyright (c) 2011-2012 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 coherent bus.
49 */
50
51#ifndef __MEM_COHERENT_BUS_HH__
52#define __MEM_COHERENT_BUS_HH__
53
54#include "mem/bus.hh"
55#include "params/CoherentBus.hh"
56
57/**
58 * A coherent bus connects a number of (potentially) snooping masters
59 * and slaves, and routes the request and response packets based on
60 * the address, and also forwards all requests to the snoopers and
61 * deals with the snoop responses.
62 *
63 * The coherent bus can be used as a template for modelling QPI,
64* HyperTransport, ACE and coherent OCP buses, and is typically used
65 * for the L1-to-L2 buses and as the main system interconnect.
66 */
67class CoherentBus : public BaseBus
68{
69
70  protected:
71
72    /**
73     * Declaration of the coherent bus slave port type, one will be
74     * instantiated for each of the master ports connecting to the
75     * bus.
76     */
77    class CoherentBusSlavePort : public SlavePort
78    {
79
80      private:
81
82        /** A reference to the bus to which this port belongs. */
83        CoherentBus &bus;
84
85      public:
86
87        CoherentBusSlavePort(const std::string &_name,
88                             CoherentBus &_bus, PortID _id)
89            : SlavePort(_name, &_bus, _id), bus(_bus)
90        { }
91
92      protected:
93
94        /**
95         * When receiving a timing request, pass it to the bus.
96         */
97        virtual bool recvTimingReq(PacketPtr pkt)
98        { return bus.recvTimingReq(pkt, id); }
99
100        /**
101         * When receiving a timing snoop response, pass it to the bus.
102         */
103        virtual bool recvTimingSnoopResp(PacketPtr pkt)
104        { return bus.recvTimingSnoopResp(pkt, id); }
105
106        /**
107         * When receiving an atomic request, pass it to the bus.
108         */
109        virtual Tick recvAtomic(PacketPtr pkt)
110        { return bus.recvAtomic(pkt, id); }
111
112        /**
113         * When receiving a functional request, pass it to the bus.
114         */
115        virtual void recvFunctional(PacketPtr pkt)
116        { bus.recvFunctional(pkt, id); }
117
118        /**
119         * When receiving a retry, pass it to the bus.
120         */
121        virtual void recvRetry()
122        { panic("Bus slave ports always succeed and should never retry.\n"); }
123
124        /**
125         * Return the union of all adress ranges seen by this bus.
126         */
127        virtual AddrRangeList getAddrRanges() const
128        { return bus.getAddrRanges(); }
129
130        /**
131         * Get the maximum block size as seen by the bus.
132         */
133        virtual unsigned deviceBlockSize() const
134        { return bus.findBlockSize(); }
135
136    };
137
138    /**
139     * Declaration of the coherent bus master port type, one will be
140     * instantiated for each of the slave interfaces connecting to the
141     * bus.
142     */
143    class CoherentBusMasterPort : public MasterPort
144    {
145      private:
146        /** A reference to the bus to which this port belongs. */
147        CoherentBus &bus;
148
149      public:
150
151        CoherentBusMasterPort(const std::string &_name,
152                              CoherentBus &_bus, PortID _id)
153            : MasterPort(_name, &_bus, _id), bus(_bus)
154        { }
155
156      protected:
157
158        /**
159         * Determine if this port should be considered a snooper. For
160         * a coherent bus master port this is always true.
161         *
162         * @return a boolean that is true if this port is snooping
163         */
164        virtual bool isSnooping() const
165        { return true; }
166
167        /**
168         * When receiving a timing response, pass it to the bus.
169         */
170        virtual bool recvTimingResp(PacketPtr pkt)
171        { return bus.recvTimingResp(pkt, id); }
172
173        /**
174         * When receiving a timing snoop request, pass it to the bus.
175         */
176        virtual void recvTimingSnoopReq(PacketPtr pkt)
177        { return bus.recvTimingSnoopReq(pkt, id); }
178
179        /**
180         * When receiving an atomic snoop request, pass it to the bus.
181         */
182        virtual Tick recvAtomicSnoop(PacketPtr pkt)
183        { return bus.recvAtomicSnoop(pkt, id); }
184
185        /**
186         * When receiving a functional snoop request, pass it to the bus.
187         */
188        virtual void recvFunctionalSnoop(PacketPtr pkt)
189        { bus.recvFunctionalSnoop(pkt, id); }
190
191        /** When reciving a range change from the peer port (at id),
192            pass it to the bus. */
193        virtual void recvRangeChange()
194        { bus.recvRangeChange(id); }
195
196        /** When reciving a retry from the peer port (at id),
197            pass it to the bus. */
198        virtual void recvRetry()
199        { bus.recvRetry(); }
200
201        // Ask the bus to ask everyone on the bus what their block size is and
202        // take the max of it. This might need to be changed a bit if we ever
203        // support multiple block sizes.
204        virtual unsigned deviceBlockSize() const
205        { return bus.findBlockSize(); }
206
207    };
208
209    std::vector<SlavePort*> snoopPorts;
210
211    /**
212     * Store the outstanding requests so we can determine which ones
213     * we generated and which ones were merely forwarded. This is used
214     * in the coherent bus when coherency responses come back.
215     */
216    std::set<RequestPtr> outstandingReq;
217
218    /** Function called by the port when the bus is recieving a Timing
219      request packet.*/
220    virtual bool recvTimingReq(PacketPtr pkt, PortID slave_port_id);
221
222    /** Function called by the port when the bus is recieving a Timing
223      response packet.*/
224    virtual bool recvTimingResp(PacketPtr pkt, PortID master_port_id);
225
226    /** Function called by the port when the bus is recieving a timing
227        snoop request.*/
228    virtual void recvTimingSnoopReq(PacketPtr pkt, PortID master_port_id);
229
230    /** Function called by the port when the bus is recieving a timing
231        snoop response.*/
232    virtual bool recvTimingSnoopResp(PacketPtr pkt, PortID slave_port_id);
233
234    /**
235     * Forward a timing packet to our snoopers, potentially excluding
236     * one of the connected coherent masters to avoid sending a packet
237     * back to where it came from.
238     *
239     * @param pkt Packet to forward
240     * @param exclude_slave_port_id Id of slave port to exclude
241     */
242    void forwardTiming(PacketPtr pkt, PortID exclude_slave_port_id);
243
244    /** Function called by the port when the bus is recieving a Atomic
245      transaction.*/
246    Tick recvAtomic(PacketPtr pkt, PortID slave_port_id);
247
248    /** Function called by the port when the bus is recieving an
249        atomic snoop transaction.*/
250    Tick recvAtomicSnoop(PacketPtr pkt, PortID master_port_id);
251
252    /**
253     * Forward an atomic packet to our snoopers, potentially excluding
254     * one of the connected coherent masters to avoid sending a packet
255     * back to where it came from.
256     *
257     * @param pkt Packet to forward
258     * @param exclude_slave_port_id Id of slave port to exclude
259     *
260     * @return a pair containing the snoop response and snoop latency
261     */
262    std::pair<MemCmd, Tick> forwardAtomic(PacketPtr pkt,
263                                          PortID exclude_slave_port_id);
264
265    /** Function called by the port when the bus is recieving a Functional
266        transaction.*/
267    void recvFunctional(PacketPtr pkt, PortID slave_port_id);
268
269    /** Function called by the port when the bus is recieving a functional
270        snoop transaction.*/
271    void recvFunctionalSnoop(PacketPtr pkt, PortID master_port_id);
272
273    /**
274     * Forward a functional packet to our snoopers, potentially
275     * excluding one of the connected coherent masters to avoid
276     * sending a packet back to where it came from.
277     *
278     * @param pkt Packet to forward
279     * @param exclude_slave_port_id Id of slave port to exclude
280     */
281    void forwardFunctional(PacketPtr pkt, PortID exclude_slave_port_id);
282
283  public:
284
285    virtual void init();
286
287    CoherentBus(const CoherentBusParams *p);
288};
289
290#endif //__MEM_COHERENT_BUS_HH__
291