voltage_domain.hh revision 10395:77b9f96786c1 
1/*
2 * Copyright (c) 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 * Redistribution and use in source and binary forms, with or without
15 * modification, are permitted provided that the following conditions are
16 * met: redistributions of source code must retain the above copyright
17 * notice, this list of conditions and the following disclaimer;
18 * redistributions in binary form must reproduce the above copyright
19 * notice, this list of conditions and the following disclaimer in the
20 * documentation and/or other materials provided with the distribution;
21 * neither the name of the copyright holders nor the names of its
22 * contributors may be used to endorse or promote products derived from
23 * this software without specific prior written permission.
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
26 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
27 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
28 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
29 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
30 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
31 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
32 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
33 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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35 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
36 *
37 * Authors: Vasileios Spiliopoulos
38 *          Akash Bagdia
39 */
40
41#ifndef __SIM_VOLTAGE_DOMAIN_HH__
42#define __SIM_VOLTAGE_DOMAIN_HH__
43
44#include <vector>
45
46#include "base/statistics.hh"
47#include "params/VoltageDomain.hh"
48#include "sim/clock_domain.hh"
49#include "sim/sim_object.hh"
50
51/**
52 * A VoltageDomain is used to group clock domains that operate under
53 * the same voltage. The class provides methods for setting and
54 * getting the voltage.
55 */
56class VoltageDomain : public SimObject
57{
58  public:
59
60    typedef VoltageDomainParams Params;
61    VoltageDomain(const Params *p);
62
63    typedef SrcClockDomain::PerfLevel PerfLevel;
64
65    /**
66     * Get the current voltage.
67     *
68     * @return Voltage of the domain
69     */
70    double voltage() const { return voltageOpPoints[_perfLevel]; }
71
72    /**
73     * Get the voltage at specified performance level.
74     *
75     * @param perf_level Performance level for which the voltage is requested
76     * @return Voltage of the domain at specified performance level
77     */
78    double voltage(PerfLevel perf_level) const
79    {
80        return voltageOpPoints[perf_level];
81    }
82
83    uint32_t numVoltages() const { return (uint32_t)voltageOpPoints.size(); }
84
85    /**
86     * Set the voltage point of the domain.
87     * @param Voltage value to be set
88     */
89    void perfLevel(PerfLevel perf_level);
90
91    /**
92     * Get the voltage point of the domain.
93     * @param Voltage value to be set
94     */
95    PerfLevel perfLevel() const { return _perfLevel; }
96
97    /**
98     * Register a SrcClockDomain with this voltage domain.
99     * @param src_clock_domain The SrcClockDomain to register.
100     */
101    void registerSrcClockDom(SrcClockDomain *src_clock_dom) {
102        assert(src_clock_dom->voltageDomain() == this);
103        srcClockChildren.push_back(src_clock_dom);
104    }
105
106    /**
107     * Startup has all SrcClockDomains registered with this voltage domain, so
108     * try to make sure that all perf level requests from them are met.
109     */
110    void startup();
111
112    /**
113     * Recomputes the highest (fastest, i.e., numerically lowest) requested
114     * performance level of all associated clock domains, and updates the
115     * performance level of this voltage domain to match.  This means that for
116     * two connected clock domains, one fast and one slow, the voltage domain
117     * will provide the voltage associated with the fast DVFS operation point.
118     * Must be called whenever a clock domain decides to swtich its performance
119     * level.
120     *
121     * @return True, if the voltage was actually changed.
122     */
123    bool sanitiseVoltages();
124
125    void regStats();
126
127    void serialize(std::ostream &os);
128    void unserialize(Checkpoint *cp, const std::string &section);
129  private:
130    typedef std::vector<double> Voltages;
131    /**
132     * List of possible minimum voltage at each of the frequency operational
133     * points, should be in descending order and same size as freqOpPoints.
134     * An empty list corresponds to default voltage specified for the voltage
135     * domain its clock domain belongs. The same voltage is applied for each
136     * freqOpPoints, overall implying NO DVS
137     */
138    const Voltages voltageOpPoints;
139    PerfLevel _perfLevel;
140
141    /**
142     * Stat for reporting voltage of the domain
143     */
144    Stats::Value currentVoltage;
145
146    /**
147     * List of associated SrcClockDomains that are connected to this voltage
148     * domain.
149     */
150    typedef std::vector<SrcClockDomain *> SrcClockChildren;
151    SrcClockChildren srcClockChildren;
152};
153
154#endif
155