intel_8254_timer.cc revision 10642:9d3b6e7dd205 
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#include "base/misc.hh"
34#include "debug/Intel8254Timer.hh"
35#include "dev/intel_8254_timer.hh"
36
37using namespace std;
38
39Intel8254Timer::Intel8254Timer(EventManager *em, const string &name,
40    Counter *counter0, Counter *counter1, Counter *counter2) :
41    EventManager(em), _name(name)
42{
43    counter[0] = counter0;
44    counter[1] = counter1;
45    counter[2] = counter2;
46}
47
48Intel8254Timer::Intel8254Timer(EventManager *em, const string &name) :
49    EventManager(em), _name(name)
50{
51    counter[0] = new Counter(this, name + ".counter0", 0);
52    counter[1] = new Counter(this, name + ".counter1", 1);
53    counter[2] = new Counter(this, name + ".counter2", 2);
54}
55
56void
57Intel8254Timer::writeControl(const CtrlReg data)
58{
59    int sel = data.sel;
60
61    if (sel == ReadBackCommand)
62       panic("PITimer Read-Back Command is not implemented.\n");
63
64    if (data.rw == LatchCommand)
65        counter[sel]->latchCount();
66    else {
67        counter[sel]->setRW(data.rw);
68        counter[sel]->setMode(data.mode);
69        counter[sel]->setBCD(data.bcd);
70    }
71}
72
73void
74Intel8254Timer::serialize(const string &base, ostream &os)
75{
76    // serialize the counters
77    counter[0]->serialize(base + ".counter0", os);
78    counter[1]->serialize(base + ".counter1", os);
79    counter[2]->serialize(base + ".counter2", os);
80}
81
82void
83Intel8254Timer::unserialize(const string &base, Checkpoint *cp,
84        const string &section)
85{
86    // unserialze the counters
87    counter[0]->unserialize(base + ".counter0", cp, section);
88    counter[1]->unserialize(base + ".counter1", cp, section);
89    counter[2]->unserialize(base + ".counter2", cp, section);
90}
91
92void
93Intel8254Timer::startup()
94{
95    counter[0]->startup();
96    counter[1]->startup();
97    counter[2]->startup();
98}
99
100Intel8254Timer::Counter::Counter(Intel8254Timer *p,
101        const string &name, unsigned int _num)
102    : _name(name), num(_num), event(this), running(false),
103      initial_count(0), latched_count(0), period(0), mode(0),
104      output_high(false), latch_on(false), read_byte(LSB),
105      write_byte(LSB), parent(p)
106{
107    offset = period * event.getInterval();
108}
109
110void
111Intel8254Timer::Counter::latchCount()
112{
113    // behave like a real latch
114    if(!latch_on) {
115        latch_on = true;
116        read_byte = LSB;
117        latched_count = currentCount();
118    }
119}
120
121int
122Intel8254Timer::Counter::currentCount()
123{
124    int clocks = event.clocksLeft();
125    if (clocks == -1) {
126        warn_once("Reading current count from inactive timer.\n");
127        return 0;
128    }
129    if (mode == RateGen || mode == SquareWave)
130        return clocks + 1;
131    else
132        return clocks;
133}
134
135uint8_t
136Intel8254Timer::Counter::read()
137{
138    if (latch_on) {
139        switch (read_byte) {
140          case LSB:
141            read_byte = MSB;
142            return (uint8_t)latched_count;
143            break;
144          case MSB:
145            read_byte = LSB;
146            latch_on = false;
147            return latched_count >> 8;
148            break;
149          default:
150            panic("Shouldn't be here");
151        }
152    } else {
153        uint16_t count = currentCount();
154        switch (read_byte) {
155          case LSB:
156            read_byte = MSB;
157            return (uint8_t)count;
158            break;
159          case MSB:
160            read_byte = LSB;
161            return count >> 8;
162            break;
163          default:
164            panic("Shouldn't be here");
165        }
166    }
167}
168
169void
170Intel8254Timer::Counter::write(const uint8_t data)
171{
172    switch (write_byte) {
173      case LSB:
174        initial_count = (initial_count & 0xFF00) | data;
175
176        if (event.scheduled())
177            parent->deschedule(event);
178        output_high = false;
179        write_byte = MSB;
180        break;
181
182      case MSB:
183        initial_count = (initial_count & 0x00FF) | (data << 8);
184        // In the RateGen or SquareWave modes, the timer wraps around and
185        // triggers on a value of 1, not 0.
186        if (mode == RateGen || mode == SquareWave)
187            period = initial_count - 1;
188        else
189            period = initial_count;
190
191        offset = period * event.getInterval();
192
193        if (running && (period > 0))
194            event.setTo(period);
195
196        write_byte = LSB;
197        break;
198    }
199}
200
201void
202Intel8254Timer::Counter::setRW(int rw_val)
203{
204    if (rw_val != TwoPhase)
205        panic("Only LSB/MSB read/write is implemented.\n");
206}
207
208void
209Intel8254Timer::Counter::setMode(int mode_val)
210{
211    if(mode_val != InitTc && mode_val != RateGen &&
212       mode_val != SquareWave)
213        panic("PIT mode %#x is not implemented: \n", mode_val);
214
215    mode = mode_val;
216}
217
218void
219Intel8254Timer::Counter::setBCD(int bcd_val)
220{
221    if (bcd_val)
222        panic("PITimer does not implement BCD counts.\n");
223}
224
225bool
226Intel8254Timer::Counter::outputHigh()
227{
228    return output_high;
229}
230
231void
232Intel8254Timer::Counter::serialize(const string &base, ostream &os)
233{
234    paramOut(os, base + ".initial_count", initial_count);
235    paramOut(os, base + ".latched_count", latched_count);
236    paramOut(os, base + ".period", period);
237    paramOut(os, base + ".mode", mode);
238    paramOut(os, base + ".output_high", output_high);
239    paramOut(os, base + ".latch_on", latch_on);
240    paramOut(os, base + ".read_byte", read_byte);
241    paramOut(os, base + ".write_byte", write_byte);
242
243    Tick event_tick_offset = 0;
244    if (event.scheduled())
245        event_tick_offset = event.when() - curTick();
246    paramOut(os, base + ".event_tick_offset", event_tick_offset);
247}
248
249void
250Intel8254Timer::Counter::unserialize(const string &base, Checkpoint *cp,
251                                         const string &section)
252{
253    paramIn(cp, section, base + ".initial_count", initial_count);
254    paramIn(cp, section, base + ".latched_count", latched_count);
255    paramIn(cp, section, base + ".period", period);
256    paramIn(cp, section, base + ".mode", mode);
257    paramIn(cp, section, base + ".output_high", output_high);
258    paramIn(cp, section, base + ".latch_on", latch_on);
259    paramIn(cp, section, base + ".read_byte", read_byte);
260    paramIn(cp, section, base + ".write_byte", write_byte);
261
262    Tick event_tick_offset = 0;
263    assert(!event.scheduled());
264    paramIn(cp, section, base + ".event_tick_offset", event_tick_offset);
265    offset = event_tick_offset;
266}
267
268void
269Intel8254Timer::Counter::startup()
270{
271    running = true;
272    if ((period > 0) && (offset > 0))
273    {
274        parent->schedule(event, curTick() + offset);
275    }
276}
277
278Intel8254Timer::Counter::CounterEvent::CounterEvent(Counter* c_ptr)
279{
280    interval = (Tick)(SimClock::Float::s / 1193180.0);
281    counter = c_ptr;
282}
283
284void
285Intel8254Timer::Counter::CounterEvent::process()
286{
287    switch (counter->mode) {
288      case InitTc:
289        counter->output_high = true;
290        break;
291      case RateGen:
292      case SquareWave:
293        setTo(counter->period);
294        break;
295      default:
296        panic("Unimplemented PITimer mode.\n");
297    }
298    counter->parent->counterInterrupt(counter->num);
299}
300
301void
302Intel8254Timer::Counter::CounterEvent::setTo(int clocks)
303{
304    if (clocks == 0)
305        panic("Timer can't be set to go off instantly.\n");
306    DPRINTF(Intel8254Timer, "Timer set to curTick() + %d\n",
307            clocks * interval);
308    counter->parent->schedule(this, curTick() + clocks * interval);
309}
310
311int
312Intel8254Timer::Counter::CounterEvent::clocksLeft()
313{
314    if (!scheduled())
315        return -1;
316    return (when() - curTick() + interval - 1) / interval;
317}
318
319const char *
320Intel8254Timer::Counter::CounterEvent::description() const
321{
322    return "Intel 8254 Interval timer";
323}
324
325Tick
326Intel8254Timer::Counter::CounterEvent::getInterval()
327{
328    return interval;
329}
330
331