intel_8254_timer.hh revision 5635 
1/*
2 * Copyright (c) 2004, 2005
3 * The Regents of The University of Michigan
4 * All Rights Reserved
5 *
6 * This code is part of the M5 simulator.
7 *
8 * Permission is granted to use, copy, create derivative works and
9 * redistribute this software and such derivative works for any
10 * purpose, so long as the copyright notice above, this grant of
11 * permission, and the disclaimer below appear in all copies made; and
12 * so long as the name of The University of Michigan is not used in
13 * any advertising or publicity pertaining to the use or distribution
14 * of this software without specific, written prior authorization.
15 *
16 * THIS SOFTWARE IS PROVIDED AS IS, WITHOUT REPRESENTATION FROM THE
17 * UNIVERSITY OF MICHIGAN AS TO ITS FITNESS FOR ANY PURPOSE, AND
18 * WITHOUT WARRANTY BY THE UNIVERSITY OF MICHIGAN OF ANY KIND, EITHER
19 * EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION THE IMPLIED
20 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
21 * PURPOSE. THE REGENTS OF THE UNIVERSITY OF MICHIGAN SHALL NOT BE
22 * LIABLE FOR ANY DAMAGES, INCLUDING DIRECT, SPECIAL, INDIRECT,
23 * INCIDENTAL, OR CONSEQUENTIAL DAMAGES, WITH RESPECT TO ANY CLAIM
24 * ARISING OUT OF OR IN CONNECTION WITH THE USE OF THE SOFTWARE, EVEN
25 * IF IT HAS BEEN OR IS HEREAFTER ADVISED OF THE POSSIBILITY OF SUCH
26 * DAMAGES.
27 *
28 * Authors: Ali G. Saidi
29 *          Andrew L. Schultz
30 *          Miguel J. Serrano
31 */
32
33#ifndef __DEV_8254_HH__
34#define __DEV_8254_HH__
35
36#include <string>
37#include <iostream>
38
39#include "base/bitunion.hh"
40#include "sim/eventq.hh"
41#include "sim/host.hh"
42#include "sim/serialize.hh"
43
44/** Programmable Interval Timer (Intel 8254) */
45class Intel8254Timer : public EventManager
46{
47  protected:
48    BitUnion8(CtrlReg)
49        Bitfield<7, 6> sel;
50        Bitfield<5, 4> rw;
51        Bitfield<3, 1> mode;
52        Bitfield<0> bcd;
53    EndBitUnion(CtrlReg)
54
55    enum SelectVal {
56        SelectCounter0,
57        SelectCounter1,
58        SelectCounter2,
59        ReadBackCommand
60    };
61
62    enum ReadWriteVal {
63        LatchCommand,
64        LsbOnly,
65        MsbOnly,
66        TwoPhase
67    };
68
69    enum ModeVal {
70        InitTc,
71        OneShot,
72        RateGen,
73        SquareWave,
74        SoftwareStrobe,
75        HardwareStrobe
76    };
77
78    /** Counter element for PIT */
79    class Counter
80    {
81        /** Event for counter interrupt */
82        class CounterEvent : public Event
83        {
84          private:
85            /** Pointer back to Counter */
86            Counter* counter;
87            Tick interval;
88
89          public:
90            CounterEvent(Counter*);
91
92            /** Event process */
93            virtual void process();
94
95            /** Event description */
96            virtual const char *description() const;
97
98            friend class Counter;
99
100            void setTo(int clocks);
101        };
102
103      private:
104        std::string _name;
105        const std::string &name() const { return _name; }
106
107        CounterEvent event;
108
109        /** Current count value */
110        uint16_t count;
111
112        /** Latched count */
113        uint16_t latched_count;
114
115        /** Interrupt period */
116        uint16_t period;
117
118        /** Current mode of operation */
119        uint8_t mode;
120
121        /** Output goes high when the counter reaches zero */
122        bool output_high;
123
124        /** State of the count latch */
125        bool latch_on;
126
127        /** Set of values for read_byte and write_byte */
128        enum {LSB, MSB};
129
130        /** Determine which byte of a 16-bit count value to read/write */
131        uint8_t read_byte, write_byte;
132
133        /** Pointer to container */
134        Intel8254Timer *parent;
135
136      public:
137        Counter(Intel8254Timer *p, const std::string &name);
138
139        /** Latch the current count (if one is not already latched) */
140        void latchCount();
141
142        /** Set the read/write mode */
143        void setRW(int rw_val);
144
145        /** Set operational mode */
146        void setMode(int mode_val);
147
148        /** Set count encoding */
149        void setBCD(int bcd_val);
150
151        /** Read a count byte */
152        uint8_t read();
153
154        /** Write a count byte */
155        void write(const uint8_t data);
156
157        /** Is the output high? */
158        bool outputHigh();
159
160        /**
161         * Serialize this object to the given output stream.
162         * @param base The base name of the counter object.
163         * @param os   The stream to serialize to.
164         */
165        void serialize(const std::string &base, std::ostream &os);
166
167        /**
168         * Reconstruct the state of this object from a checkpoint.
169         * @param base The base name of the counter object.
170         * @param cp The checkpoint use.
171         * @param section The section name of this object
172         */
173        void unserialize(const std::string &base, Checkpoint *cp,
174                         const std::string &section);
175    };
176
177  protected:
178    std::string _name;
179    const std::string &name() const { return _name; }
180
181    /** PIT has three seperate counters */
182    Counter *counter[3];
183
184  public:
185
186    Intel8254Timer(EventManager *em, const std::string &name,
187            Counter *counter0, Counter *counter1, Counter *counter2);
188
189    Intel8254Timer(EventManager *em, const std::string &name);
190
191    /** Write control word */
192    void writeControl(const CtrlReg data);
193
194    uint8_t
195    readCounter(unsigned int num)
196    {
197        assert(num < 3);
198        return counter[num]->read();
199    }
200
201    void
202    writeCounter(unsigned int num, const uint8_t data)
203    {
204        assert(num < 3);
205        counter[num]->write(data);
206    }
207
208    bool
209    outputHigh(unsigned int num)
210    {
211        assert(num < 3);
212        return counter[num]->outputHigh();
213    }
214
215    /**
216     * Serialize this object to the given output stream.
217     * @param base The base name of the counter object.
218     * @param os The stream to serialize to.
219     */
220    void serialize(const std::string &base, std::ostream &os);
221
222    /**
223     * Reconstruct the state of this object from a checkpoint.
224     * @param base The base name of the counter object.
225     * @param cp The checkpoint use.
226     * @param section The section name of this object
227     */
228    void unserialize(const std::string &base, Checkpoint *cp,
229                     const std::string &section);
230};
231
232#endif // __DEV_8254_HH__
233