intel_8254_timer.cc revision 7903:7fcfb515d7bf 
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 "dev/intel_8254_timer.hh"
35
36using namespace std;
37
38Intel8254Timer::Intel8254Timer(EventManager *em, const string &name,
39    Counter *counter0, Counter *counter1, Counter *counter2) :
40    EventManager(em), _name(name)
41{
42    counter[0] = counter0;
43    counter[1] = counter1;
44    counter[2] = counter2;
45}
46
47Intel8254Timer::Intel8254Timer(EventManager *em, const string &name) :
48    EventManager(em), _name(name)
49{
50    counter[0] = new Counter(this, name + ".counter0", 0);
51    counter[1] = new Counter(this, name + ".counter1", 1);
52    counter[2] = new Counter(this, name + ".counter2", 2);
53}
54
55void
56Intel8254Timer::writeControl(const CtrlReg data)
57{
58    int sel = data.sel;
59
60    if (sel == ReadBackCommand)
61       panic("PITimer Read-Back Command is not implemented.\n");
62
63    if (data.rw == LatchCommand)
64        counter[sel]->latchCount();
65    else {
66        counter[sel]->setRW(data.rw);
67        counter[sel]->setMode(data.mode);
68        counter[sel]->setBCD(data.bcd);
69    }
70}
71
72void
73Intel8254Timer::serialize(const string &base, ostream &os)
74{
75    // serialize the counters
76    counter[0]->serialize(base + ".counter0", os);
77    counter[1]->serialize(base + ".counter1", os);
78    counter[2]->serialize(base + ".counter2", os);
79}
80
81void
82Intel8254Timer::unserialize(const string &base, Checkpoint *cp,
83        const string &section)
84{
85    // unserialze the counters
86    counter[0]->unserialize(base + ".counter0", cp, section);
87    counter[1]->unserialize(base + ".counter1", cp, section);
88    counter[2]->unserialize(base + ".counter2", cp, section);
89}
90
91Intel8254Timer::Counter::Counter(Intel8254Timer *p,
92        const string &name, unsigned int _num)
93    : _name(name), num(_num), event(this), initial_count(0),
94      latched_count(0), period(0), mode(0), output_high(false),
95      latch_on(false), read_byte(LSB), write_byte(LSB), parent(p)
96{
97
98}
99
100void
101Intel8254Timer::Counter::latchCount()
102{
103    // behave like a real latch
104    if(!latch_on) {
105        latch_on = true;
106        read_byte = LSB;
107        latched_count = currentCount();
108    }
109}
110
111int
112Intel8254Timer::Counter::currentCount()
113{
114    int clocks = event.clocksLeft();
115    if (clocks == -1) {
116        warn_once("Reading current count from inactive timer.\n");
117        return 0;
118    }
119    if (mode == RateGen || mode == SquareWave)
120        return clocks + 1;
121    else
122        return clocks;
123}
124
125uint8_t
126Intel8254Timer::Counter::read()
127{
128    if (latch_on) {
129        switch (read_byte) {
130          case LSB:
131            read_byte = MSB;
132            return (uint8_t)latched_count;
133            break;
134          case MSB:
135            read_byte = LSB;
136            latch_on = false;
137            return latched_count >> 8;
138            break;
139          default:
140            panic("Shouldn't be here");
141        }
142    } else {
143        uint16_t count = currentCount();
144        switch (read_byte) {
145          case LSB:
146            read_byte = MSB;
147            return (uint8_t)count;
148            break;
149          case MSB:
150            read_byte = LSB;
151            return count >> 8;
152            break;
153          default:
154            panic("Shouldn't be here");
155        }
156    }
157}
158
159void
160Intel8254Timer::Counter::write(const uint8_t data)
161{
162    switch (write_byte) {
163      case LSB:
164        initial_count = (initial_count & 0xFF00) | data;
165
166        if (event.scheduled())
167            parent->deschedule(event);
168        output_high = false;
169        write_byte = MSB;
170        break;
171
172      case MSB:
173        initial_count = (initial_count & 0x00FF) | (data << 8);
174        // In the RateGen or SquareWave modes, the timer wraps around and
175        // triggers on a value of 1, not 0.
176        if (mode == RateGen || mode == SquareWave)
177            period = initial_count - 1;
178        else
179            period = initial_count;
180
181        if (period > 0)
182            event.setTo(period);
183
184        write_byte = LSB;
185        break;
186    }
187}
188
189void
190Intel8254Timer::Counter::setRW(int rw_val)
191{
192    if (rw_val != TwoPhase)
193        panic("Only LSB/MSB read/write is implemented.\n");
194}
195
196void
197Intel8254Timer::Counter::setMode(int mode_val)
198{
199    if(mode_val != InitTc && mode_val != RateGen &&
200       mode_val != SquareWave)
201        panic("PIT mode %#x is not implemented: \n", mode_val);
202
203    mode = mode_val;
204}
205
206void
207Intel8254Timer::Counter::setBCD(int bcd_val)
208{
209    if (bcd_val)
210        panic("PITimer does not implement BCD counts.\n");
211}
212
213bool
214Intel8254Timer::Counter::outputHigh()
215{
216    return output_high;
217}
218
219void
220Intel8254Timer::Counter::serialize(const string &base, ostream &os)
221{
222    paramOut(os, base + ".initial_count", initial_count);
223    paramOut(os, base + ".latched_count", latched_count);
224    paramOut(os, base + ".period", period);
225    paramOut(os, base + ".mode", mode);
226    paramOut(os, base + ".output_high", output_high);
227    paramOut(os, base + ".latch_on", latch_on);
228    paramOut(os, base + ".read_byte", read_byte);
229    paramOut(os, base + ".write_byte", write_byte);
230
231    Tick event_tick = 0;
232    if (event.scheduled())
233        event_tick = event.when();
234    paramOut(os, base + ".event_tick", event_tick);
235}
236
237void
238Intel8254Timer::Counter::unserialize(const string &base, Checkpoint *cp,
239                                         const string &section)
240{
241    paramIn(cp, section, base + ".initial_count", initial_count);
242    paramIn(cp, section, base + ".latched_count", latched_count);
243    paramIn(cp, section, base + ".period", period);
244    paramIn(cp, section, base + ".mode", mode);
245    paramIn(cp, section, base + ".output_high", output_high);
246    paramIn(cp, section, base + ".latch_on", latch_on);
247    paramIn(cp, section, base + ".read_byte", read_byte);
248    paramIn(cp, section, base + ".write_byte", write_byte);
249
250    Tick event_tick = 0;
251    if (event.scheduled())
252        parent->deschedule(event);
253    paramIn(cp, section, base + ".event_tick", event_tick);
254    if (event_tick)
255        parent->schedule(event, event_tick);
256}
257
258Intel8254Timer::Counter::CounterEvent::CounterEvent(Counter* c_ptr)
259{
260    interval = (Tick)(SimClock::Float::s / 1193180.0);
261    counter = c_ptr;
262}
263
264void
265Intel8254Timer::Counter::CounterEvent::process()
266{
267    switch (counter->mode) {
268      case InitTc:
269        counter->output_high = true;
270        break;
271      case RateGen:
272      case SquareWave:
273        setTo(counter->period);
274        break;
275      default:
276        panic("Unimplemented PITimer mode.\n");
277    }
278    counter->parent->counterInterrupt(counter->num);
279}
280
281void
282Intel8254Timer::Counter::CounterEvent::setTo(int clocks)
283{
284    if (clocks == 0)
285        panic("Timer can't be set to go off instantly.\n");
286    DPRINTF(Intel8254Timer, "Timer set to curTick() + %d\n",
287            clocks * interval);
288    counter->parent->schedule(this, curTick() + clocks * interval);
289}
290
291int
292Intel8254Timer::Counter::CounterEvent::clocksLeft()
293{
294    if (!scheduled())
295        return -1;
296    return (when() - curTick() + interval - 1) / interval;
297}
298
299const char *
300Intel8254Timer::Counter::CounterEvent::description() const
301{
302    return "Intel 8254 Interval timer";
303}
304