intel_8254_timer.hh revision 5642:102cf92b8ea9 
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            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        unsigned int num;
108
109        CounterEvent event;
110
111        /** Current count value */
112        uint16_t count;
113
114        /** Latched count */
115        uint16_t latched_count;
116
117        /** Interrupt period */
118        uint16_t period;
119
120        /** Current mode of operation */
121        uint8_t mode;
122
123        /** Output goes high when the counter reaches zero */
124        bool output_high;
125
126        /** State of the count latch */
127        bool latch_on;
128
129        /** Set of values for read_byte and write_byte */
130        enum {LSB, MSB};
131
132        /** Determine which byte of a 16-bit count value to read/write */
133        uint8_t read_byte, write_byte;
134
135        /** Pointer to container */
136        Intel8254Timer *parent;
137
138      public:
139        Counter(Intel8254Timer *p, const std::string &name, unsigned int num);
140
141        /** Latch the current count (if one is not already latched) */
142        void latchCount();
143
144        /** Set the read/write mode */
145        void setRW(int rw_val);
146
147        /** Set operational mode */
148        void setMode(int mode_val);
149
150        /** Set count encoding */
151        void setBCD(int bcd_val);
152
153        /** Read a count byte */
154        uint8_t read();
155
156        /** Write a count byte */
157        void write(const uint8_t data);
158
159        /** Is the output high? */
160        bool outputHigh();
161
162        /**
163         * Serialize this object to the given output stream.
164         * @param base The base name of the counter object.
165         * @param os   The stream to serialize to.
166         */
167        void serialize(const std::string &base, std::ostream &os);
168
169        /**
170         * Reconstruct the state of this object from a checkpoint.
171         * @param base The base name of the counter object.
172         * @param cp The checkpoint use.
173         * @param section The section name of this object
174         */
175        void unserialize(const std::string &base, Checkpoint *cp,
176                         const std::string &section);
177    };
178
179  protected:
180    std::string _name;
181    const std::string &name() const { return _name; }
182
183    /** PIT has three seperate counters */
184    Counter *counter[3];
185
186    virtual void
187    counterInterrupt(unsigned int num)
188    {
189        DPRINTF(Intel8254Timer, "Timer interrupt from counter %d.\n", num);
190    }
191
192  public:
193
194    virtual
195    ~Intel8254Timer()
196    {}
197
198    Intel8254Timer(EventManager *em, const std::string &name,
199            Counter *counter0, Counter *counter1, Counter *counter2);
200
201    Intel8254Timer(EventManager *em, const std::string &name);
202
203    /** Write control word */
204    void writeControl(const CtrlReg data);
205
206    uint8_t
207    readCounter(unsigned int num)
208    {
209        assert(num < 3);
210        return counter[num]->read();
211    }
212
213    void
214    writeCounter(unsigned int num, const uint8_t data)
215    {
216        assert(num < 3);
217        counter[num]->write(data);
218    }
219
220    bool
221    outputHigh(unsigned int num)
222    {
223        assert(num < 3);
224        return counter[num]->outputHigh();
225    }
226
227    /**
228     * Serialize this object to the given output stream.
229     * @param base The base name of the counter object.
230     * @param os The stream to serialize to.
231     */
232    void serialize(const std::string &base, std::ostream &os);
233
234    /**
235     * Reconstruct the state of this object from a checkpoint.
236     * @param base The base name of the counter object.
237     * @param cp The checkpoint use.
238     * @param section The section name of this object
239     */
240    void unserialize(const std::string &base, Checkpoint *cp,
241                     const std::string &section);
242};
243
244#endif // __DEV_8254_HH__
245