serial_link.hh revision 12823 
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        EventFunctionWrapper sendEvent;
150
151      public:
152
153        /**
154         * Constructor for the SerialLinkSlavePort.
155         *
156         * @param _name the port name including the owner
157         * @param _serial_link the structural owner
158         * @param _masterPort the master port on the other side of the
159         * serial_link
160         * @param _delay the delay in cycles from receiving to sending
161         * @param _resp_limit the size of the response queue
162         * @param _ranges a number of address ranges to forward
163         */
164        SerialLinkSlavePort(const std::string& _name, SerialLink&
165                        _serial_link, SerialLinkMasterPort& _masterPort,
166                        Cycles _delay, int _resp_limit, const
167                        std::vector<AddrRange>& _ranges);
168
169        /**
170         * Queue a response packet to be sent out later and also schedule
171         * a send if necessary.
172         *
173         * @param pkt a response to send out after a delay
174         * @param when tick when response packet should be sent
175         */
176        void schedTimingResp(PacketPtr pkt, Tick when);
177
178        /**
179         * Retry any stalled request that we have failed to accept at
180         * an earlier point in time. This call will do nothing if no
181         * request is waiting.
182         */
183        void retryStalledReq();
184
185      protected:
186
187        /** When receiving a timing request from the peer port,
188            pass it to the serial_link. */
189        bool recvTimingReq(PacketPtr pkt);
190
191        /** When receiving a retry request from the peer port,
192            pass it to the serial_link. */
193        void recvRespRetry();
194
195        /** When receiving a Atomic requestfrom the peer port,
196            pass it to the serial_link. */
197        Tick recvAtomic(PacketPtr pkt);
198
199        /** When receiving a Functional request from the peer port,
200            pass it to the serial_link. */
201        void recvFunctional(PacketPtr pkt);
202
203        /** When receiving a address range request the peer port,
204            pass it to the serial_link. */
205        AddrRangeList getAddrRanges() const;
206    };
207
208
209    /**
210     * Port on the side that forwards requests and receives
211     * responses. The master port has a buffer for the requests not
212     * yet sent.
213     */
214    class SerialLinkMasterPort : public MasterPort
215    {
216
217      private:
218
219        /** The serial_link to which this port belongs. */
220        SerialLink& serial_link;
221
222        /**
223         * The slave port on the other side of the serial_link.
224         */
225        SerialLinkSlavePort& slavePort;
226
227        /** Minimum delay though this serial_link. */
228        const Cycles delay;
229
230        /**
231         * Request packet queue. Request packets are held in this
232         * queue for a specified delay to model the processing delay
233         * of the serial_link.  We use a deque as we need to iterate over
234         * the items for functional accesses.
235         */
236        std::deque<DeferredPacket> transmitList;
237
238        /** Max queue size for request packets */
239        const unsigned int reqQueueLimit;
240
241        /**
242         * Handle send event, scheduled when the packet at the head of
243         * the outbound queue is ready to transmit (for timing
244         * accesses only).
245         */
246        void trySendTiming();
247
248        /** Send event for the request queue. */
249        EventFunctionWrapper sendEvent;
250
251      public:
252
253        /**
254         * Constructor for the SerialLinkMasterPort.
255         *
256         * @param _name the port name including the owner
257         * @param _serial_link the structural owner
258         * @param _slavePort the slave port on the other side of the
259         * serial_link
260         * @param _delay the delay in cycles from receiving to sending
261         * @param _req_limit the size of the request queue
262         */
263        SerialLinkMasterPort(const std::string& _name, SerialLink&
264                         _serial_link, SerialLinkSlavePort& _slavePort, Cycles
265                         _delay, int _req_limit);
266
267        /**
268         * Is this side blocked from accepting new request packets.
269         *
270         * @return true if the occupied space has reached the set limit
271         */
272        bool reqQueueFull() const;
273
274        /**
275         * Queue a request packet to be sent out later and also schedule
276         * a send if necessary.
277         *
278         * @param pkt a request to send out after a delay
279         * @param when tick when response packet should be sent
280         */
281        void schedTimingReq(PacketPtr pkt, Tick when);
282
283        /**
284         * Check a functional request against the packets in our
285         * request queue.
286         *
287         * @param pkt packet to check against
288         *
289         * @return true if we find a match
290         */
291        bool trySatisfyFunctional(PacketPtr pkt);
292
293      protected:
294
295        /** When receiving a timing request from the peer port,
296            pass it to the serial_link. */
297        bool recvTimingResp(PacketPtr pkt);
298
299        /** When receiving a retry request from the peer port,
300            pass it to the serial_link. */
301        void recvReqRetry();
302    };
303
304    /** Slave port of the serial_link. */
305    SerialLinkSlavePort slavePort;
306
307    /** Master port of the serial_link. */
308    SerialLinkMasterPort masterPort;
309
310    /** Number of parallel lanes in this serial link */
311    unsigned num_lanes;
312
313    /** Speed of each link (Gb/s) in this serial link */
314    uint64_t link_speed;
315
316  public:
317
318    virtual BaseMasterPort& getMasterPort(const std::string& if_name,
319                                          PortID idx = InvalidPortID);
320    virtual BaseSlavePort& getSlavePort(const std::string& if_name,
321                                        PortID idx = InvalidPortID);
322
323    virtual void init();
324
325    typedef SerialLinkParams Params;
326
327    SerialLink(SerialLinkParams *p);
328};
329
330#endif //__MEM_SERIAL_LINK_HH__
331