intel_8254_timer.hh revision 9356:b279bad40aa3 
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 <iostream>
37#include <string>
38
39#include "base/bitunion.hh"
40#include "base/types.hh"
41#include "base/trace.hh"
42#include "debug/Intel8254Timer.hh"
43#include "sim/eventq_impl.hh"
44#include "sim/serialize.hh"
45
46/** Programmable Interval Timer (Intel 8254) */
47class Intel8254Timer : public EventManager
48{
49  protected:
50    BitUnion8(CtrlReg)
51        Bitfield<7, 6> sel;
52        Bitfield<5, 4> rw;
53        Bitfield<3, 1> mode;
54        Bitfield<0> bcd;
55    EndBitUnion(CtrlReg)
56
57    enum SelectVal {
58        SelectCounter0,
59        SelectCounter1,
60        SelectCounter2,
61        ReadBackCommand
62    };
63
64    enum ReadWriteVal {
65        LatchCommand,
66        LsbOnly,
67        MsbOnly,
68        TwoPhase
69    };
70
71    enum ModeVal {
72        InitTc,
73        OneShot,
74        RateGen,
75        SquareWave,
76        SoftwareStrobe,
77        HardwareStrobe
78    };
79
80    /** Counter element for PIT */
81    class Counter
82    {
83        /** Event for counter interrupt */
84        class CounterEvent : public Event
85        {
86          private:
87            /** Pointer back to Counter */
88            Counter* counter;
89            Tick interval;
90
91          public:
92            CounterEvent(Counter*);
93
94            /** Event process */
95            void process();
96
97            /** Event description */
98            virtual const char *description() const;
99
100            friend class Counter;
101
102            void setTo(int clocks);
103
104            int clocksLeft();
105        };
106
107      private:
108        std::string _name;
109        const std::string &name() const { return _name; }
110
111        unsigned int num;
112
113        CounterEvent event;
114
115        /** Initial count value */
116        uint16_t initial_count;
117
118        /** Latched count */
119        uint16_t latched_count;
120
121        /** Interrupt period */
122        uint16_t period;
123
124        /** Current mode of operation */
125        uint8_t mode;
126
127        /** Output goes high when the counter reaches zero */
128        bool output_high;
129
130        /** State of the count latch */
131        bool latch_on;
132
133        /** Set of values for read_byte and write_byte */
134        enum {LSB, MSB};
135
136        /** Determine which byte of a 16-bit count value to read/write */
137        uint8_t read_byte, write_byte;
138
139        /** Pointer to container */
140        Intel8254Timer *parent;
141
142      public:
143        Counter(Intel8254Timer *p, const std::string &name, unsigned int num);
144
145        /** Latch the current count (if one is not already latched) */
146        void latchCount();
147
148        /** Get the current count for this counter */
149        int currentCount();
150
151        /** Set the read/write mode */
152        void setRW(int rw_val);
153
154        /** Set operational mode */
155        void setMode(int mode_val);
156
157        /** Set count encoding */
158        void setBCD(int bcd_val);
159
160        /** Read a count byte */
161        uint8_t read();
162
163        /** Write a count byte */
164        void write(const uint8_t data);
165
166        /** Is the output high? */
167        bool outputHigh();
168
169        /**
170         * Serialize this object to the given output stream.
171         * @param base The base name of the counter object.
172         * @param os   The stream to serialize to.
173         */
174        void serialize(const std::string &base, std::ostream &os);
175
176        /**
177         * Reconstruct the state of this object from a checkpoint.
178         * @param base The base name of the counter object.
179         * @param cp The checkpoint use.
180         * @param section The section name of this object
181         */
182        void unserialize(const std::string &base, Checkpoint *cp,
183                         const std::string &section);
184    };
185
186  protected:
187    std::string _name;
188    const std::string &name() const { return _name; }
189
190    /** PIT has three seperate counters */
191    Counter *counter[3];
192
193    virtual void
194    counterInterrupt(unsigned int num)
195    {
196        DPRINTF(Intel8254Timer, "Timer interrupt from counter %d.\n", num);
197    }
198
199  public:
200
201    virtual
202    ~Intel8254Timer()
203    {}
204
205    Intel8254Timer(EventManager *em, const std::string &name,
206            Counter *counter0, Counter *counter1, Counter *counter2);
207
208    Intel8254Timer(EventManager *em, const std::string &name);
209
210    /** Write control word */
211    void writeControl(const CtrlReg data);
212
213    uint8_t
214    readCounter(unsigned int num)
215    {
216        assert(num < 3);
217        return counter[num]->read();
218    }
219
220    void
221    writeCounter(unsigned int num, const uint8_t data)
222    {
223        assert(num < 3);
224        counter[num]->write(data);
225    }
226
227    bool
228    outputHigh(unsigned int num)
229    {
230        assert(num < 3);
231        return counter[num]->outputHigh();
232    }
233
234    /**
235     * Serialize this object to the given output stream.
236     * @param base The base name of the counter object.
237     * @param os The stream to serialize to.
238     */
239    void serialize(const std::string &base, std::ostream &os);
240
241    /**
242     * Reconstruct the state of this object from a checkpoint.
243     * @param base The base name of the counter object.
244     * @param cp The checkpoint use.
245     * @param section The section name of this object
246     */
247    void unserialize(const std::string &base, Checkpoint *cp,
248                     const std::string &section);
249};
250
251#endif // __DEV_8254_HH__
252