serial_link.hh revision 11185 
1/*
2 * Copyright (c) 2011-2013 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) 2006 The Regents of The University of Michigan
15 * Copyright (c) 2015 The University of Bologna
16 * All rights reserved.
17 *
18 * Redistribution and use in source and binary forms, with or without
19 * modification, are permitted provided that the following conditions are
20 * met: redistributions of source code must retain the above copyright
21 * notice, this list of conditions and the following disclaimer;
22 * redistributions in binary form must reproduce the above copyright
23 * notice, this list of conditions and the following disclaimer in the
24 * documentation and/or other materials provided with the distribution;
25 * neither the name of the copyright holders nor the names of its
26 * contributors may be used to endorse or promote products derived from
27 * this software without specific prior written permission.
28 *
29 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
30 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
31 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
32 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
33 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
34 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
35 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
36 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
37 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
38 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
39 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
40 *
41 * Authors: Ali Saidi
42 *          Steve Reinhardt
43 *          Andreas Hansson
44 *          Erfan Azarkhish
45 */
46
47/**
48 * @file
49 * Declaration of the SerialLink Class, modeling Hybrid-Memory-Cube's serial
50 * interface.
51 */
52
53#ifndef __MEM_SERIAL_LINK_HH__
54#define __MEM_SERIAL_LINK_HH__
55
56#include <deque>
57
58#include "base/types.hh"
59#include "mem/mem_object.hh"
60#include "params/SerialLink.hh"
61
62/**
63 * SerialLink is a simple variation of the Bridge class, with the ability to
64 * account for the latency of packet serialization. We assume that the
65 * serializer component at the transmitter side does not need to receive the
66 * whole packet to start the serialization. But the deserializer waits for the
67 * complete packet to check its integrity first.
68  */
69class SerialLink : public MemObject
70{
71  protected:
72
73    /**
74     * A deferred packet stores a packet along with its scheduled
75     * transmission time
76     */
77    class DeferredPacket
78    {
79
80      public:
81
82        const Tick tick;
83        const PacketPtr pkt;
84
85        DeferredPacket(PacketPtr _pkt, Tick _tick) : tick(_tick), pkt(_pkt)
86        { }
87    };
88
89    // Forward declaration to allow the slave port to have a pointer
90    class SerialLinkMasterPort;
91
92    /**
93     * The port on the side that receives requests and sends
94     * responses. The slave port has a set of address ranges that it
95     * is responsible for. The slave port also has a buffer for the
96     * responses not yet sent.
97     */
98    class SerialLinkSlavePort : public SlavePort
99    {
100
101      private:
102
103        /** The serial_link to which this port belongs. */
104        SerialLink& serial_link;
105
106        /**
107         * Master port on the other side of the serial_link.
108         */
109        SerialLinkMasterPort& masterPort;
110
111        /** Minimum request delay though this serial_link. */
112        const Cycles delay;
113
114        /** Address ranges to pass through the serial_link */
115        const AddrRangeList ranges;
116
117        /**
118         * Response packet queue. Response packets are held in this
119         * queue for a specified delay to model the processing delay
120         * of the serial_link. We use a deque as we need to iterate over
121         * the items for functional accesses.
122         */
123        std::deque<DeferredPacket> transmitList;
124
125        /** Counter to track the outstanding responses. */
126        unsigned int outstandingResponses;
127
128        /** If we should send a retry when space becomes available. */
129        bool retryReq;
130
131        /** Max queue size for reserved responses. */
132        unsigned int respQueueLimit;
133
134        /**
135         * Is this side blocked from accepting new response packets.
136         *
137         * @return true if the reserved space has reached the set limit
138         */
139        bool respQueueFull() const;
140
141        /**
142         * Handle send event, scheduled when the packet at the head of
143         * the response queue is ready to transmit (for timing
144         * accesses only).
145         */
146        void trySendTiming();
147
148        /** Send event for the response queue. */
149        EventWrapper<SerialLinkSlavePort,
150                     &SerialLinkSlavePort::trySendTiming> sendEvent;
151
152      public:
153
154        /**
155         * Constructor for the SerialLinkSlavePort.
156         *
157         * @param _name the port name including the owner
158         * @param _serial_link the structural owner
159         * @param _masterPort the master port on the other side of the
160         * serial_link
161         * @param _delay the delay in cycles from receiving to sending
162         * @param _resp_limit the size of the response queue
163         * @param _ranges a number of address ranges to forward
164         */
165        SerialLinkSlavePort(const std::string& _name, SerialLink&
166                        _serial_link, SerialLinkMasterPort& _masterPort,
167                        Cycles _delay, int _resp_limit, const
168                        std::vector<AddrRange>& _ranges);
169
170        /**
171         * Queue a response packet to be sent out later and also schedule
172         * a send if necessary.
173         *
174         * @param pkt a response to send out after a delay
175         * @param when tick when response packet should be sent
176         */
177        void schedTimingResp(PacketPtr pkt, Tick when);
178
179        /**
180         * Retry any stalled request that we have failed to accept at
181         * an earlier point in time. This call will do nothing if no
182         * request is waiting.
183         */
184        void retryStalledReq();
185
186      protected:
187
188        /** When receiving a timing request from the peer port,
189            pass it to the serial_link. */
190        bool recvTimingReq(PacketPtr pkt);
191
192        /** When receiving a retry request from the peer port,
193            pass it to the serial_link. */
194        void recvRespRetry();
195
196        /** When receiving a Atomic requestfrom the peer port,
197            pass it to the serial_link. */
198        Tick recvAtomic(PacketPtr pkt);
199
200        /** When receiving a Functional request from the peer port,
201            pass it to the serial_link. */
202        void recvFunctional(PacketPtr pkt);
203
204        /** When receiving a address range request the peer port,
205            pass it to the serial_link. */
206        AddrRangeList getAddrRanges() const;
207    };
208
209
210    /**
211     * Port on the side that forwards requests and receives
212     * responses. The master port has a buffer for the requests not
213     * yet sent.
214     */
215    class SerialLinkMasterPort : public MasterPort
216    {
217
218      private:
219
220        /** The serial_link to which this port belongs. */
221        SerialLink& serial_link;
222
223        /**
224         * The slave port on the other side of the serial_link.
225         */
226        SerialLinkSlavePort& slavePort;
227
228        /** Minimum delay though this serial_link. */
229        const Cycles delay;
230
231        /**
232         * Request packet queue. Request packets are held in this
233         * queue for a specified delay to model the processing delay
234         * of the serial_link.  We use a deque as we need to iterate over
235         * the items for functional accesses.
236         */
237        std::deque<DeferredPacket> transmitList;
238
239        /** Max queue size for request packets */
240        const unsigned int reqQueueLimit;
241
242        /**
243         * Handle send event, scheduled when the packet at the head of
244         * the outbound queue is ready to transmit (for timing
245         * accesses only).
246         */
247        void trySendTiming();
248
249        /** Send event for the request queue. */
250        EventWrapper<SerialLinkMasterPort,
251                     &SerialLinkMasterPort::trySendTiming> sendEvent;
252
253      public:
254
255        /**
256         * Constructor for the SerialLinkMasterPort.
257         *
258         * @param _name the port name including the owner
259         * @param _serial_link the structural owner
260         * @param _slavePort the slave port on the other side of the
261         * serial_link
262         * @param _delay the delay in cycles from receiving to sending
263         * @param _req_limit the size of the request queue
264         */
265        SerialLinkMasterPort(const std::string& _name, SerialLink&
266                         _serial_link, SerialLinkSlavePort& _slavePort, Cycles
267                         _delay, int _req_limit);
268
269        /**
270         * Is this side blocked from accepting new request packets.
271         *
272         * @return true if the occupied space has reached the set limit
273         */
274        bool reqQueueFull() const;
275
276        /**
277         * Queue a request packet to be sent out later and also schedule
278         * a send if necessary.
279         *
280         * @param pkt a request to send out after a delay
281         * @param when tick when response packet should be sent
282         */
283        void schedTimingReq(PacketPtr pkt, Tick when);
284
285        /**
286         * Check a functional request against the packets in our
287         * request queue.
288         *
289         * @param pkt packet to check against
290         *
291         * @return true if we find a match
292         */
293        bool checkFunctional(PacketPtr pkt);
294
295      protected:
296
297        /** When receiving a timing request from the peer port,
298            pass it to the serial_link. */
299        bool recvTimingResp(PacketPtr pkt);
300
301        /** When receiving a retry request from the peer port,
302            pass it to the serial_link. */
303        void recvReqRetry();
304    };
305
306    /** Slave port of the serial_link. */
307    SerialLinkSlavePort slavePort;
308
309    /** Master port of the serial_link. */
310    SerialLinkMasterPort masterPort;
311
312    /** Number of parallel lanes in this serial link */
313    unsigned num_lanes;
314
315  public:
316
317    virtual BaseMasterPort& getMasterPort(const std::string& if_name,
318                                          PortID idx = InvalidPortID);
319    virtual BaseSlavePort& getSlavePort(const std::string& if_name,
320                                        PortID idx = InvalidPortID);
321
322    virtual void init();
323
324    typedef SerialLinkParams Params;
325
326    SerialLink(SerialLinkParams *p);
327};
328
329#endif //__MEM_SERIAL_LINK_HH__
330