energy_ctrl.hh revision 10396 
1/*
2 * Copyright (c) 2012-2014 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
34 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
35 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
36 *
37 * Authors: Vasileios Spiliopoulos
38 *          Akash Bagdia
39 *          Stephan Diestelhorst
40 */
41
42/**
43 * @file
44 * The energy controller is a device being used to manage power and energy
45 * related control operations within the system. It provides the necessary
46 * software interface to the kernel. The kernel will require gem5 specific
47 * drivers to access this device.
48 *
49 * Tasks handled by the controller are:
50 * a) Dynamic voltage and frequency scaling control operations
51 *
52 * Note that the registers defined do not resemble any specific controller
53 * device in real hardware. They are currently design to accomodate the gem5
54 * system requirements.
55 */
56
57#ifndef __DEV_ARM_ENERGY_CTRL_HH__
58#define __DEV_ARM_ENERGY_CTRL_HH__
59
60#include "dev/io_device.hh"
61#include "params/EnergyCtrl.hh"
62
63class DVFSHandler;
64
65class EnergyCtrl : public BasicPioDevice
66{
67  public:
68    /**
69     * Discovery flows:
70     * ----------------
71     *   * get basic DVFS handler information
72     *     read(DVFS_HANDLER_STATUS)
73     *     read(DVFS_HANDLER_TRANS_LATENCY)
74     *
75     *   * get the number of domain IDs
76     *     read(DVFS_NUM_DOMAINS) -> domains
77     *
78     *   * query the driver to get the IDs for all i in domains
79     *     write(DVFS_DOMAINID_AT_INDEX <- i)
80     *     read(DOMAIN_ID) -> domainID_i
81     *
82     *   * for each domainID i get voltage / frequency pairs
83     *     write(DOMAIN_ID <- domainID_i)
84     *     read(NUM_OF_PERF_LEVELS) -> levels_i
85     *     * for each l in levels_i
86     *       write(PERF_LEVEL_TO_READ <- l)
87     *       read(FREQ_AT_PERF_LEVEL) -> freq_l_i
88     *       read(VOLT_AT_PERF_LEVEL) -> volt_l_i
89     *
90     *
91     * Setting a specific performance level (V/F combination)
92     * ------------------------------------------------------
93     *   * get performance for domain_ID i
94     *     write(DOMAIN_ID <- i)
95     *     read(PERF_LEVEL) -> perf_level_i
96     *
97     *   * set performance for domain_ID i
98     *     write(DOMAIN_ID <- i)
99     *     write(PERF_LEVEL <- perf_level_i)
100     *     * wait for DVFS transition completion
101     *       while (!read(PERF_LEVEL_ACK));
102     */
103
104    enum Registers {
105        DVFS_HANDLER_STATUS = 0,
106        DVFS_NUM_DOMAINS,
107        DVFS_DOMAINID_AT_INDEX,
108        DVFS_HANDLER_TRANS_LATENCY,
109        DOMAIN_ID,
110        PERF_LEVEL,
111        PERF_LEVEL_ACK,
112        NUM_OF_PERF_LEVELS,
113        PERF_LEVEL_TO_READ,
114        FREQ_AT_PERF_LEVEL,
115        VOLT_AT_PERF_LEVEL,
116        PIO_NUM_FIELDS
117    };
118
119    typedef EnergyCtrlParams Params;
120    EnergyCtrl(const Params *p);
121
122    /**
123     * Read command sent to the device
124     * @param pkt Packet describing this request
125     * @return number of ticks it took to complete
126     */
127    virtual Tick read(PacketPtr pkt);
128    /**
129     * Write command sent to the device
130     * @param pkt Packet describing this request
131     * @return number of ticks it took to complete
132     */
133    virtual Tick write(PacketPtr pkt);
134
135    void serialize(std::ostream &os);
136    void unserialize(Checkpoint *cp, const std::string &section);
137
138    void startup();
139    void init();
140
141  private:
142    DVFSHandler *dvfsHandler;
143
144    /**
145     * Cluster ID (DOMAIN_ID) R/W register, programmed to ID of the domain for
146     * which the set/get performance level command can be issued
147     */
148    uint32_t domainID;
149
150    /**
151     * Index for getting the domain ID from the domain ID list available with
152     * the DVFS handler
153     */
154    uint32_t domainIDIndexToRead;
155
156    /**
157     * Acknowledgment (PERF_LEVEL_ACK) RO register, software polls this
158     * register to read back the status of the last programmed change in the
159     * domain ID and/or the performance level. Valid values are:
160     * '0' - Ack is not OK yet
161     * '1' - Ack is OK
162     * It is a read destructive register with a read of '1' resets the ack to
163     * '0'.
164     */
165    uint32_t perfLevelAck;
166
167    uint32_t perfLevelToRead;
168
169    static uint32_t ticksTokHz(Tick period) {
170        return (uint32_t)(SimClock::Int::ms / period);
171    }
172
173    static uint32_t toMicroVolt(double voltage) {
174        return (uint32_t)(voltage * 1000000);
175    }
176
177    /**
178      * Update the acknowledgment that is read back by the software to confirm
179      * newly requested performance level has been set.
180     */
181    void updatePLAck() {
182        perfLevelAck = 1;
183    }
184
185    EventWrapper<EnergyCtrl, &EnergyCtrl::updatePLAck> updateAckEvent;
186};
187#endif //__DEV_ARM_ENERGY_CTRL_HH__
188