1/*
2 * Copyright (c) 2011-2015, 2018 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 an abstract crossbar base class.
49 */
50
51#ifndef __MEM_XBAR_HH__
52#define __MEM_XBAR_HH__
53
54#include <deque>
55#include <unordered_map>
56
57#include "base/addr_range_map.hh"
58#include "base/types.hh"
59#include "mem/qport.hh"
60#include "params/BaseXBar.hh"
61#include "sim/clocked_object.hh"
62#include "sim/stats.hh"
63
64/**
65 * The base crossbar contains the common elements of the non-coherent
66 * and coherent crossbar. It is an abstract class that does not have
67 * any of the functionality relating to the actual reception and
68 * transmission of packets, as this is left for the subclasses.
69 *
70 * The BaseXBar is responsible for the basic flow control (busy or
71 * not), the administration of retries, and the address decoding.
72 */
73class BaseXBar : public ClockedObject
74{
75
76  protected:
77
78    /**
79     * A layer is an internal crossbar arbitration point with its own
80     * flow control. Each layer is a converging multiplexer tree. By
81     * instantiating one layer per destination port (and per packet
82     * type, i.e. request, response, snoop request and snoop
83     * response), we model full crossbar structures like AXI, ACE,
84     * PCIe, etc.
85     *
86     * The template parameter, PortClass, indicates the destination
87     * port type for the layer. The retry list holds either master
88     * ports or slave ports, depending on the direction of the
89     * layer. Thus, a request layer has a retry list containing slave
90     * ports, whereas a response layer holds master ports.
91     */
92    template <typename SrcType, typename DstType>
93    class Layer : public Drainable
94    {
95
96      public:
97
98        /**
99         * Create a layer and give it a name. The layer uses
100         * the crossbar an event manager.
101         *
102         * @param _port destination port the layer converges at
103         * @param _xbar the crossbar this layer belongs to
104         * @param _name the layer's name
105         */
106        Layer(DstType& _port, BaseXBar& _xbar, const std::string& _name);
107
108        /**
109         * Drain according to the normal semantics, so that the crossbar
110         * can tell the layer to drain, and pass an event to signal
111         * back when drained.
112         *
113         * @param de drain event to call once drained
114         *
115         * @return 1 if busy or waiting to retry, or 0 if idle
116         */
117        DrainState drain() override;
118
119        const std::string name() const { return xbar.name() + _name; }
120
121
122        /**
123         * Determine if the layer accepts a packet from a specific
124         * port. If not, the port in question is also added to the
125         * retry list. In either case the state of the layer is
126         * updated accordingly.
127         *
128         * @param port Source port presenting the packet
129         *
130         * @return True if the layer accepts the packet
131         */
132        bool tryTiming(SrcType* src_port);
133
134        /**
135         * Deal with a destination port accepting a packet by potentially
136         * removing the source port from the retry list (if retrying) and
137         * occupying the layer accordingly.
138         *
139         * @param busy_time Time to spend as a result of a successful send
140         */
141        void succeededTiming(Tick busy_time);
142
143        /**
144         * Deal with a destination port not accepting a packet by
145         * potentially adding the source port to the retry list (if
146         * not already at the front) and occupying the layer
147         * accordingly.
148         *
149         * @param src_port Source port
150         * @param busy_time Time to spend as a result of a failed send
151         */
152        void failedTiming(SrcType* src_port, Tick busy_time);
153
154        void occupyLayer(Tick until);
155
156        /**
157         * Send a retry to the port at the head of waitingForLayer. The
158         * caller must ensure that the list is not empty.
159         */
160        void retryWaiting();
161
162        /**
163         * Handle a retry from a neighbouring module. This wraps
164         * retryWaiting by verifying that there are ports waiting
165         * before calling retryWaiting.
166         */
167        void recvRetry();
168
169        void regStats();
170
171      protected:
172
173        /**
174         * Sending the actual retry, in a manner specific to the
175         * individual layers. Note that for a MasterPort, there is
176         * both a RequestLayer and a SnoopResponseLayer using the same
177         * port, but using different functions for the flow control.
178         */
179        virtual void sendRetry(SrcType* retry_port) = 0;
180
181      private:
182
183        /** The destination port this layer converges at. */
184        DstType& port;
185
186        /** The crossbar this layer is a part of. */
187        BaseXBar& xbar;
188
189        std::string _name;
190
191        /**
192         * We declare an enum to track the state of the layer. The
193         * starting point is an idle state where the layer is waiting
194         * for a packet to arrive. Upon arrival, the layer
195         * transitions to the busy state, where it remains either
196         * until the packet transfer is done, or the header time is
197         * spent. Once the layer leaves the busy state, it can
198         * either go back to idle, if no packets have arrived while it
199         * was busy, or the layer goes on to retry the first port
200         * in waitingForLayer. A similar transition takes place from
201         * idle to retry if the layer receives a retry from one of
202         * its connected ports. The retry state lasts until the port
203         * in questions calls sendTiming and returns control to the
204         * layer, or goes to a busy state if the port does not
205         * immediately react to the retry by calling sendTiming.
206         */
207        enum State { IDLE, BUSY, RETRY };
208
209        State state;
210
211        /**
212         * A deque of ports that retry should be called on because
213         * the original send was delayed due to a busy layer.
214         */
215        std::deque<SrcType*> waitingForLayer;
216
217        /**
218         * Track who is waiting for the retry when receiving it from a
219         * peer. If no port is waiting NULL is stored.
220         */
221        SrcType* waitingForPeer;
222
223        /**
224         * Release the layer after being occupied and return to an
225         * idle state where we proceed to send a retry to any
226         * potential waiting port, or drain if asked to do so.
227         */
228        void releaseLayer();
229        EventFunctionWrapper releaseEvent;
230
231        /**
232         * Stats for occupancy and utilization. These stats capture
233         * the time the layer spends in the busy state and are thus only
234         * relevant when the memory system is in timing mode.
235         */
236        Stats::Scalar occupancy;
237        Stats::Formula utilization;
238
239    };
240
241    class ReqLayer : public Layer<SlavePort, MasterPort>
242    {
243      public:
244        /**
245         * Create a request layer and give it a name.
246         *
247         * @param _port destination port the layer converges at
248         * @param _xbar the crossbar this layer belongs to
249         * @param _name the layer's name
250         */
251        ReqLayer(MasterPort& _port, BaseXBar& _xbar, const std::string& _name) :
252            Layer(_port, _xbar, _name)
253        {}
254
255      protected:
256        void
257        sendRetry(SlavePort* retry_port) override
258        {
259            retry_port->sendRetryReq();
260        }
261    };
262
263    class RespLayer : public Layer<MasterPort, SlavePort>
264    {
265      public:
266        /**
267         * Create a response layer and give it a name.
268         *
269         * @param _port destination port the layer converges at
270         * @param _xbar the crossbar this layer belongs to
271         * @param _name the layer's name
272         */
273        RespLayer(SlavePort& _port, BaseXBar& _xbar,
274                  const std::string& _name) :
275            Layer(_port, _xbar, _name)
276        {}
277
278      protected:
279        void
280        sendRetry(MasterPort* retry_port) override
281        {
282            retry_port->sendRetryResp();
283        }
284    };
285
286    class SnoopRespLayer : public Layer<SlavePort, MasterPort>
287    {
288      public:
289        /**
290         * Create a snoop response layer and give it a name.
291         *
292         * @param _port destination port the layer converges at
293         * @param _xbar the crossbar this layer belongs to
294         * @param _name the layer's name
295         */
296        SnoopRespLayer(MasterPort& _port, BaseXBar& _xbar,
297                       const std::string& _name) :
298            Layer(_port, _xbar, _name)
299        {}
300
301      protected:
302
303        void
304        sendRetry(SlavePort* retry_port) override
305        {
306            retry_port->sendRetrySnoopResp();
307        }
308    };
309
310    /**
311     * Cycles of front-end pipeline including the delay to accept the request
312     * and to decode the address.
313     */
314    const Cycles frontendLatency;
315    const Cycles forwardLatency;
316    const Cycles responseLatency;
317    /** the width of the xbar in bytes */
318    const uint32_t width;
319
320    AddrRangeMap<PortID, 3> portMap;
321
322    /**
323     * Remember where request packets came from so that we can route
324     * responses to the appropriate port. This relies on the fact that
325     * the underlying Request pointer inside the Packet stays
326     * constant.
327     */
328    std::unordered_map<RequestPtr, PortID> routeTo;
329
330    /** all contigous ranges seen by this crossbar */
331    AddrRangeList xbarRanges;
332
333    AddrRange defaultRange;
334
335    /**
336     * Function called by the port when the crossbar is recieving a
337     * range change.
338     *
339     * @param master_port_id id of the port that received the change
340     */
341    virtual void recvRangeChange(PortID master_port_id);
342
343    /**
344     * Find which port connected to this crossbar (if any) should be
345     * given a packet with this address range.
346     *
347     * @param addr_range Address range to find port for.
348     * @return id of port that the packet should be sent out of.
349     */
350    PortID findPort(AddrRange addr_range);
351
352    /**
353     * Return the address ranges the crossbar is responsible for.
354     *
355     * @return a list of non-overlapping address ranges
356     */
357    AddrRangeList getAddrRanges() const;
358
359    /**
360     * Calculate the timing parameters for the packet. Updates the
361     * headerDelay and payloadDelay fields of the packet
362     * object with the relative number of ticks required to transmit
363     * the header and the payload, respectively.
364     *
365     * @param pkt Packet to populate with timings
366     * @param header_delay Header delay to be added
367     */
368    void calcPacketTiming(PacketPtr pkt, Tick header_delay);
369
370    /**
371     * Remember for each of the master ports of the crossbar if we got
372     * an address range from the connected slave. For convenience,
373     * also keep track of if we got ranges from all the slave modules
374     * or not.
375     */
376    std::vector<bool> gotAddrRanges;
377    bool gotAllAddrRanges;
378
379    /** The master and slave ports of the crossbar */
380    std::vector<QueuedSlavePort*> slavePorts;
381    std::vector<MasterPort*> masterPorts;
382
383    /** Port that handles requests that don't match any of the interfaces.*/
384    PortID defaultPortID;
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    const bool useDefaultRange;
391
392    BaseXBar(const BaseXBarParams *p);
393
394    /**
395     * Stats for transaction distribution and data passing through the
396     * crossbar. The transaction distribution is globally counting
397     * different types of commands. The packet count and total packet
398     * size are two-dimensional vectors that are indexed by the
399     * slave port and master port id (thus the neighbouring master and
400     * neighbouring slave), summing up both directions (request and
401     * response).
402     */
403    Stats::Vector transDist;
404    Stats::Vector2d pktCount;
405    Stats::Vector2d pktSize;
406
407  public:
408
409    virtual ~BaseXBar();
410
411    /** A function used to return the port associated with this object. */
412    Port &getPort(const std::string &if_name,
413                  PortID idx=InvalidPortID) override;
414
415    void regStats() override;
416};
417
418#endif //__MEM_XBAR_HH__
419