intel_8254_timer.cc revision 10905:a6ca6831e775 
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, CheckpointOut &cp) const
75{
76    // serialize the counters
77    counter[0]->serialize(base + ".counter0", cp);
78    counter[1]->serialize(base + ".counter1", cp);
79    counter[2]->serialize(base + ".counter2", cp);
80}
81
82void
83Intel8254Timer::unserialize(const string &base, CheckpointIn &cp)
84{
85    // unserialze the counters
86    counter[0]->unserialize(base + ".counter0", cp);
87    counter[1]->unserialize(base + ".counter1", cp);
88    counter[2]->unserialize(base + ".counter2", cp);
89}
90
91void
92Intel8254Timer::startup()
93{
94    counter[0]->startup();
95    counter[1]->startup();
96    counter[2]->startup();
97}
98
99Intel8254Timer::Counter::Counter(Intel8254Timer *p,
100        const string &name, unsigned int _num)
101    : _name(name), num(_num), event(this), running(false),
102      initial_count(0), latched_count(0), period(0), mode(0),
103      output_high(false), latch_on(false), read_byte(LSB),
104      write_byte(LSB), parent(p)
105{
106    offset = period * event.getInterval();
107}
108
109void
110Intel8254Timer::Counter::latchCount()
111{
112    // behave like a real latch
113    if(!latch_on) {
114        latch_on = true;
115        read_byte = LSB;
116        latched_count = currentCount();
117    }
118}
119
120int
121Intel8254Timer::Counter::currentCount()
122{
123    int clocks = event.clocksLeft();
124    if (clocks == -1) {
125        warn_once("Reading current count from inactive timer.\n");
126        return 0;
127    }
128    if (mode == RateGen || mode == SquareWave)
129        return clocks + 1;
130    else
131        return clocks;
132}
133
134uint8_t
135Intel8254Timer::Counter::read()
136{
137    if (latch_on) {
138        switch (read_byte) {
139          case LSB:
140            read_byte = MSB;
141            return (uint8_t)latched_count;
142            break;
143          case MSB:
144            read_byte = LSB;
145            latch_on = false;
146            return latched_count >> 8;
147            break;
148          default:
149            panic("Shouldn't be here");
150        }
151    } else {
152        uint16_t count = currentCount();
153        switch (read_byte) {
154          case LSB:
155            read_byte = MSB;
156            return (uint8_t)count;
157            break;
158          case MSB:
159            read_byte = LSB;
160            return count >> 8;
161            break;
162          default:
163            panic("Shouldn't be here");
164        }
165    }
166}
167
168void
169Intel8254Timer::Counter::write(const uint8_t data)
170{
171    switch (write_byte) {
172      case LSB:
173        initial_count = (initial_count & 0xFF00) | data;
174
175        if (event.scheduled())
176            parent->deschedule(event);
177        output_high = false;
178        write_byte = MSB;
179        break;
180
181      case MSB:
182        initial_count = (initial_count & 0x00FF) | (data << 8);
183        // In the RateGen or SquareWave modes, the timer wraps around and
184        // triggers on a value of 1, not 0.
185        if (mode == RateGen || mode == SquareWave)
186            period = initial_count - 1;
187        else
188            period = initial_count;
189
190        offset = period * event.getInterval();
191
192        if (running && (period > 0))
193            event.setTo(period);
194
195        write_byte = LSB;
196        break;
197    }
198}
199
200void
201Intel8254Timer::Counter::setRW(int rw_val)
202{
203    if (rw_val != TwoPhase)
204        panic("Only LSB/MSB read/write is implemented.\n");
205}
206
207void
208Intel8254Timer::Counter::setMode(int mode_val)
209{
210    if(mode_val != InitTc && mode_val != RateGen &&
211       mode_val != SquareWave)
212        panic("PIT mode %#x is not implemented: \n", mode_val);
213
214    mode = mode_val;
215}
216
217void
218Intel8254Timer::Counter::setBCD(int bcd_val)
219{
220    if (bcd_val)
221        panic("PITimer does not implement BCD counts.\n");
222}
223
224bool
225Intel8254Timer::Counter::outputHigh()
226{
227    return output_high;
228}
229
230void
231Intel8254Timer::Counter::serialize(const string &base, CheckpointOut &cp) const
232{
233    paramOut(cp, base + ".initial_count", initial_count);
234    paramOut(cp, base + ".latched_count", latched_count);
235    paramOut(cp, base + ".period", period);
236    paramOut(cp, base + ".mode", mode);
237    paramOut(cp, base + ".output_high", output_high);
238    paramOut(cp, base + ".latch_on", latch_on);
239    paramOut(cp, base + ".read_byte", read_byte);
240    paramOut(cp, base + ".write_byte", write_byte);
241
242    Tick event_tick_offset = 0;
243    if (event.scheduled())
244        event_tick_offset = event.when() - curTick();
245    paramOut(cp, base + ".event_tick_offset", event_tick_offset);
246}
247
248void
249Intel8254Timer::Counter::unserialize(const string &base, CheckpointIn &cp)
250{
251    paramIn(cp, base + ".initial_count", initial_count);
252    paramIn(cp, base + ".latched_count", latched_count);
253    paramIn(cp, base + ".period", period);
254    paramIn(cp, base + ".mode", mode);
255    paramIn(cp, base + ".output_high", output_high);
256    paramIn(cp, base + ".latch_on", latch_on);
257    paramIn(cp, base + ".read_byte", read_byte);
258    paramIn(cp, base + ".write_byte", write_byte);
259
260    Tick event_tick_offset = 0;
261    assert(!event.scheduled());
262    paramIn(cp, base + ".event_tick_offset", event_tick_offset);
263    offset = event_tick_offset;
264}
265
266void
267Intel8254Timer::Counter::startup()
268{
269    running = true;
270    if ((period > 0) && (offset > 0))
271    {
272        parent->schedule(event, curTick() + offset);
273    }
274}
275
276Intel8254Timer::Counter::CounterEvent::CounterEvent(Counter* c_ptr)
277{
278    interval = (Tick)(SimClock::Float::s / 1193180.0);
279    counter = c_ptr;
280}
281
282void
283Intel8254Timer::Counter::CounterEvent::process()
284{
285    switch (counter->mode) {
286      case InitTc:
287        counter->output_high = true;
288        break;
289      case RateGen:
290      case SquareWave:
291        setTo(counter->period);
292        break;
293      default:
294        panic("Unimplemented PITimer mode.\n");
295    }
296    counter->parent->counterInterrupt(counter->num);
297}
298
299void
300Intel8254Timer::Counter::CounterEvent::setTo(int clocks)
301{
302    if (clocks == 0)
303        panic("Timer can't be set to go off instantly.\n");
304    DPRINTF(Intel8254Timer, "Timer set to curTick() + %d\n",
305            clocks * interval);
306    counter->parent->schedule(this, curTick() + clocks * interval);
307}
308
309int
310Intel8254Timer::Counter::CounterEvent::clocksLeft()
311{
312    if (!scheduled())
313        return -1;
314    return (when() - curTick() + interval - 1) / interval;
315}
316
317const char *
318Intel8254Timer::Counter::CounterEvent::description() const
319{
320    return "Intel 8254 Interval timer";
321}
322
323Tick
324Intel8254Timer::Counter::CounterEvent::getInterval()
325{
326    return interval;
327}
328
329