clock_domain.hh revision 11416:a10d9e2ef671 
1/*
2 * Copyright (c) 2013-2014 ARM Limited
3 * Copyright (c) 2013 Cornell University
4 * All rights reserved
5 *
6 * The license below extends only to copyright in the software and shall
7 * not be construed as granting a license to any other intellectual
8 * property including but not limited to intellectual property relating
9 * to a hardware implementation of the functionality of the software
10 * licensed hereunder.  You may use the software subject to the license
11 * terms below provided that you ensure that this notice is replicated
12 * unmodified and in its entirety in all distributions of the software,
13 * modified or unmodified, in source code or in binary form.
14 *
15 * Redistribution and use in source and binary forms, with or without
16 * modification, are permitted provided that the following conditions are
17 * met: redistributions of source code must retain the above copyright
18 * notice, this list of conditions and the following disclaimer;
19 * redistributions in binary form must reproduce the above copyright
20 * notice, this list of conditions and the following disclaimer in the
21 * documentation and/or other materials provided with the distribution;
22 * neither the name of the copyright holders nor the names of its
23 * contributors may be used to endorse or promote products derived from
24 * this software without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
27 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
28 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
29 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
30 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
31 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
32 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
33 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
34 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
35 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
36 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
37 *
38 * Authors: Vasileios Spiliopoulos
39 *          Akash Bagdia
40 *          Christopher Torng
41 *          Stephan Diestelhorst
42 */
43
44/**
45 * @file
46 * ClockDomain declarations.
47 */
48
49#ifndef __SIM_CLOCK_DOMAIN_HH__
50#define __SIM_CLOCK_DOMAIN_HH__
51
52#include <algorithm>
53
54#include "base/statistics.hh"
55#include "params/ClockDomain.hh"
56#include "params/DerivedClockDomain.hh"
57#include "params/SrcClockDomain.hh"
58#include "sim/sim_object.hh"
59
60/**
61 * Forward declaration
62 */
63class DerivedClockDomain;
64class VoltageDomain;
65class Clocked;
66
67/**
68 * The ClockDomain provides clock to group of clocked objects bundled
69 * under the same clock domain. The clock domains, in turn, are
70 * grouped into voltage domains. The clock domains provide support for
71 * a hierarchial structure with source and derived domains.
72 */
73class ClockDomain : public SimObject
74{
75
76  private:
77
78    /**
79     * Stat to report clock period of clock domain
80     */
81    Stats::Value currentClock;
82
83  protected:
84
85    /**
86     * Pre-computed clock period in ticks. This is populated by the
87     * inheriting classes based on how their period is determined.
88     */
89    Tick _clockPeriod;
90
91    /**
92     * Voltage domain this clock domain belongs to
93     */
94    VoltageDomain *_voltageDomain;
95
96    /**
97     * Pointers to potential derived clock domains so we can propagate
98     * changes.
99     */
100    std::vector<DerivedClockDomain*> children;
101
102    /**
103     * Pointers to members of this clock domain, so that when the clock
104     * period changes, we can update each member's tick.
105     */
106    std::vector<Clocked *> members;
107
108  public:
109
110    typedef ClockDomainParams Params;
111    ClockDomain(const Params *p, VoltageDomain *voltage_domain) :
112        SimObject(p),
113        _clockPeriod(0),
114        _voltageDomain(voltage_domain) {}
115
116    void regStats();
117
118    /**
119     * Get the clock period.
120     *
121     * @return Clock period in ticks
122     */
123    Tick clockPeriod() const { return _clockPeriod; }
124
125    /**
126     * Register a Clocked object with this ClockDomain.
127     *
128     * @param Clocked to add as a member
129     */
130    void registerWithClockDomain(Clocked *c)
131    {
132        assert(c != NULL);
133        assert(std::find(members.begin(), members.end(), c) == members.end());
134        members.push_back(c);
135    }
136
137    /**
138     * Get the voltage domain.
139     *
140     * @return Voltage domain this clock domain belongs to
141     */
142    inline VoltageDomain *voltageDomain() const { return _voltageDomain; }
143
144
145    /**
146     * Get the current voltage this clock domain operates at.
147     *
148     * @return Voltage applied to the clock domain
149     */
150    double voltage() const;
151
152    /**
153     * Add a derived domain.
154     *
155     * @param Derived domain to add as a child
156     */
157    void addDerivedDomain(DerivedClockDomain *clock_domain)
158    { children.push_back(clock_domain); }
159
160};
161
162/**
163 * The source clock domains provides the notion of a clock domain that is
164 * connected to a tunable clock source. It maintains the clock period and
165 * provides methods for setting/getting the clock and  configuration parameters
166 * for clock domain that handler is going to manage. This includes frequency
167 * values at various performance levels, domain id, and current performance
168 * level. Note that a performance level as requested by the software corresponds
169 * to one of the frequency operational points the domain can operate at.
170 */
171class SrcClockDomain : public ClockDomain
172{
173
174  public:
175
176    typedef SrcClockDomainParams Params;
177    SrcClockDomain(const Params *p);
178
179    /**
180     * Set new clock value
181     * @param clock The new clock period in ticks
182     */
183    void clockPeriod(Tick clock_period);
184
185    // Explicitly import the otherwise hidden clockPeriod
186    using ClockDomain::clockPeriod;
187
188    typedef int32_t DomainID;
189    static const DomainID emptyDomainID = -1;
190
191    /**
192     * @return the domainID of the domain
193     */
194    uint32_t domainID() const { return _domainID; }
195
196    typedef uint32_t PerfLevel;
197    /**
198     * Checks whether the performance level requested exists in the current
199     * domain configuration
200     *
201     * @param the target performance level of the domain
202     *
203     * @return validity status of the given performance level
204     */
205    bool validPerfLevel(PerfLevel perf_level) const {
206        return perf_level < numPerfLevels();
207    }
208
209    /**
210     * Sets the current performance level of the domain
211     *
212     * @param perf_level the target performance level
213     */
214    void perfLevel(PerfLevel perf_level);
215
216    /**
217     * @return the current performance level of the domain
218     */
219    PerfLevel perfLevel() const { return _perfLevel; }
220
221    /**
222     * Get the number of available performance levels for this clock domain.
223     *
224     * @return Number of perf levels configured for this domain.
225     */
226    PerfLevel numPerfLevels() const {return freqOpPoints.size();}
227
228    /**
229     * @returns the clock period (expressed in ticks) for the current
230     * performance level
231     */
232    Tick clkPeriodAtPerfLevel() const { return freqOpPoints[perfLevel()]; }
233
234    Tick clkPeriodAtPerfLevel(PerfLevel perf_level) const
235    {
236        assert(validPerfLevel(perf_level));
237        return freqOpPoints[perf_level];
238    }
239
240    void startup() override;
241
242    void serialize(CheckpointOut &cp) const override;
243    void unserialize(CheckpointIn &cp) override;
244
245  private:
246    /**
247     * Inform other components about the changed performance level
248     */
249    void signalPerfLevelUpdate();
250
251    /**
252      * List of possible frequency operational points, should be in
253      * descending order
254      * An empty list corresponds to default frequency specified for its
255      * clock domain, overall implying NO DVFS
256      */
257    const std::vector<Tick> freqOpPoints;
258
259    /**
260      * Software recognizable id number for the domain, should be unique for
261      * each domain
262      */
263    const uint32_t _domainID;
264
265    /**
266      * Current performance level the domain is set to.
267      * The performance level corresponds to one selected frequency (and related
268      * voltage) from the supplied list of frequencies, with perfLevel = 0 being
269      * the fastest performance state.
270      */
271    PerfLevel _perfLevel;
272};
273
274/**
275 * The derived clock domains provides the notion of a clock domain
276 * that is connected to a parent clock domain that can either be a
277 * source clock domain or a derived clock domain. It maintains the
278 * clock divider and provides methods for getting the clock.
279 */
280class DerivedClockDomain: public ClockDomain
281{
282
283  public:
284
285    typedef DerivedClockDomainParams Params;
286    DerivedClockDomain(const Params *p);
287
288    /**
289     * Called by the parent clock domain to propagate changes. This
290     * also involves propagating the change further to any children of
291     * the derived domain itself.
292     */
293    void updateClockPeriod();
294
295  private:
296
297    /**
298     * Reference to the parent clock domain this clock domain derives
299     * its clock period from
300     */
301    ClockDomain &parent;
302
303    /**
304     * Local clock divider of the domain
305     */
306    const uint64_t clockDivider;
307};
308
309#endif
310