FreeBSD/Linux Kernel Cross Reference
sys/amd64/isa/clock.c
1 /*-
2 * Copyright (c) 1990 The Regents of the University of California.
3 * All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * William Jolitz and Don Ahn.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 4. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 *
32 * from: @(#)clock.c 7.2 (Berkeley) 5/12/91
33 */
34
35 #include <sys/cdefs.h>
36 __FBSDID("$FreeBSD: releng/8.0/sys/amd64/isa/clock.c 194790 2009-06-23 23:16:37Z mav $");
37
38 /*
39 * Routines to handle clock hardware.
40 */
41
42 #include "opt_clock.h"
43 #include "opt_isa.h"
44
45 #include <sys/param.h>
46 #include <sys/systm.h>
47 #include <sys/bus.h>
48 #include <sys/lock.h>
49 #include <sys/kdb.h>
50 #include <sys/mutex.h>
51 #include <sys/proc.h>
52 #include <sys/timetc.h>
53 #include <sys/kernel.h>
54 #include <sys/module.h>
55 #include <sys/sched.h>
56 #include <sys/smp.h>
57 #include <sys/sysctl.h>
58
59 #include <machine/clock.h>
60 #include <machine/cpu.h>
61 #include <machine/intr_machdep.h>
62 #include <machine/md_var.h>
63 #include <machine/apicvar.h>
64 #include <machine/ppireg.h>
65 #include <machine/timerreg.h>
66 #include <machine/smp.h>
67
68 #include <isa/rtc.h>
69 #ifdef DEV_ISA
70 #include <isa/isareg.h>
71 #include <isa/isavar.h>
72 #endif
73
74 #define TIMER_DIV(x) ((i8254_freq + (x) / 2) / (x))
75
76 int clkintr_pending;
77 static int pscnt = 1;
78 static int psdiv = 1;
79 #ifndef TIMER_FREQ
80 #define TIMER_FREQ 1193182
81 #endif
82 u_int i8254_freq = TIMER_FREQ;
83 TUNABLE_INT("hw.i8254.freq", &i8254_freq);
84 int i8254_max_count;
85 static int i8254_real_max_count;
86
87 struct mtx clock_lock;
88 static struct intsrc *i8254_intsrc;
89 static u_int32_t i8254_lastcount;
90 static u_int32_t i8254_offset;
91 static int (*i8254_pending)(struct intsrc *);
92 static int i8254_ticked;
93 static int using_atrtc_timer;
94 static int using_lapic_timer;
95
96 /* Values for timerX_state: */
97 #define RELEASED 0
98 #define RELEASE_PENDING 1
99 #define ACQUIRED 2
100 #define ACQUIRE_PENDING 3
101
102 static u_char timer2_state;
103
104 static unsigned i8254_get_timecount(struct timecounter *tc);
105 static unsigned i8254_simple_get_timecount(struct timecounter *tc);
106 static void set_i8254_freq(u_int freq, int intr_freq);
107
108 static struct timecounter i8254_timecounter = {
109 i8254_get_timecount, /* get_timecount */
110 0, /* no poll_pps */
111 ~0u, /* counter_mask */
112 0, /* frequency */
113 "i8254", /* name */
114 0 /* quality */
115 };
116
117 int
118 hardclockintr(struct trapframe *frame)
119 {
120
121 if (PCPU_GET(cpuid) == 0)
122 hardclock(TRAPF_USERMODE(frame), TRAPF_PC(frame));
123 else
124 hardclock_cpu(TRAPF_USERMODE(frame));
125 return (FILTER_HANDLED);
126 }
127
128 int
129 statclockintr(struct trapframe *frame)
130 {
131
132 profclockintr(frame);
133 statclock(TRAPF_USERMODE(frame));
134 return (FILTER_HANDLED);
135 }
136
137 int
138 profclockintr(struct trapframe *frame)
139 {
140
141 if (!using_atrtc_timer)
142 hardclockintr(frame);
143 if (profprocs != 0)
144 profclock(TRAPF_USERMODE(frame), TRAPF_PC(frame));
145 return (FILTER_HANDLED);
146 }
147
148 static int
149 clkintr(struct trapframe *frame)
150 {
151
152 if (timecounter->tc_get_timecount == i8254_get_timecount) {
153 mtx_lock_spin(&clock_lock);
154 if (i8254_ticked)
155 i8254_ticked = 0;
156 else {
157 i8254_offset += i8254_max_count;
158 i8254_lastcount = 0;
159 }
160 clkintr_pending = 0;
161 mtx_unlock_spin(&clock_lock);
162 }
163 KASSERT(!using_lapic_timer, ("clk interrupt enabled with lapic timer"));
164
165 if (using_atrtc_timer) {
166 #ifdef SMP
167 if (smp_started)
168 ipi_all_but_self(IPI_HARDCLOCK);
169 #endif
170 hardclockintr(frame);
171 } else {
172 if (--pscnt <= 0) {
173 pscnt = psratio;
174 #ifdef SMP
175 if (smp_started)
176 ipi_all_but_self(IPI_STATCLOCK);
177 #endif
178 statclockintr(frame);
179 } else {
180 #ifdef SMP
181 if (smp_started)
182 ipi_all_but_self(IPI_PROFCLOCK);
183 #endif
184 profclockintr(frame);
185 }
186 }
187
188 return (FILTER_HANDLED);
189 }
190
191 int
192 timer_spkr_acquire(void)
193 {
194 int mode;
195
196 mode = TIMER_SEL2 | TIMER_SQWAVE | TIMER_16BIT;
197
198 if (timer2_state != RELEASED)
199 return (-1);
200 timer2_state = ACQUIRED;
201
202 /*
203 * This access to the timer registers is as atomic as possible
204 * because it is a single instruction. We could do better if we
205 * knew the rate. Use of splclock() limits glitches to 10-100us,
206 * and this is probably good enough for timer2, so we aren't as
207 * careful with it as with timer0.
208 */
209 outb(TIMER_MODE, TIMER_SEL2 | (mode & 0x3f));
210 ppi_spkr_on(); /* enable counter2 output to speaker */
211 return (0);
212 }
213
214 int
215 timer_spkr_release(void)
216 {
217
218 if (timer2_state != ACQUIRED)
219 return (-1);
220 timer2_state = RELEASED;
221 outb(TIMER_MODE, TIMER_SEL2 | TIMER_SQWAVE | TIMER_16BIT);
222 ppi_spkr_off(); /* disable counter2 output to speaker */
223 return (0);
224 }
225
226 void
227 timer_spkr_setfreq(int freq)
228 {
229
230 freq = i8254_freq / freq;
231 mtx_lock_spin(&clock_lock);
232 outb(TIMER_CNTR2, freq & 0xff);
233 outb(TIMER_CNTR2, freq >> 8);
234 mtx_unlock_spin(&clock_lock);
235 }
236
237 /*
238 * This routine receives statistical clock interrupts from the RTC.
239 * As explained above, these occur at 128 interrupts per second.
240 * When profiling, we receive interrupts at a rate of 1024 Hz.
241 *
242 * This does not actually add as much overhead as it sounds, because
243 * when the statistical clock is active, the hardclock driver no longer
244 * needs to keep (inaccurate) statistics on its own. This decouples
245 * statistics gathering from scheduling interrupts.
246 *
247 * The RTC chip requires that we read status register C (RTC_INTR)
248 * to acknowledge an interrupt, before it will generate the next one.
249 * Under high interrupt load, rtcintr() can be indefinitely delayed and
250 * the clock can tick immediately after the read from RTC_INTR. In this
251 * case, the mc146818A interrupt signal will not drop for long enough
252 * to register with the 8259 PIC. If an interrupt is missed, the stat
253 * clock will halt, considerably degrading system performance. This is
254 * why we use 'while' rather than a more straightforward 'if' below.
255 * Stat clock ticks can still be lost, causing minor loss of accuracy
256 * in the statistics, but the stat clock will no longer stop.
257 */
258 static int
259 rtcintr(struct trapframe *frame)
260 {
261 int flag = 0;
262
263 while (rtcin(RTC_INTR) & RTCIR_PERIOD) {
264 flag = 1;
265 if (--pscnt <= 0) {
266 pscnt = psdiv;
267 #ifdef SMP
268 if (smp_started)
269 ipi_all_but_self(IPI_STATCLOCK);
270 #endif
271 statclockintr(frame);
272 } else {
273 #ifdef SMP
274 if (smp_started)
275 ipi_all_but_self(IPI_PROFCLOCK);
276 #endif
277 profclockintr(frame);
278 }
279 }
280 return(flag ? FILTER_HANDLED : FILTER_STRAY);
281 }
282
283 static int
284 getit(void)
285 {
286 int high, low;
287
288 mtx_lock_spin(&clock_lock);
289
290 /* Select timer0 and latch counter value. */
291 outb(TIMER_MODE, TIMER_SEL0 | TIMER_LATCH);
292
293 low = inb(TIMER_CNTR0);
294 high = inb(TIMER_CNTR0);
295
296 mtx_unlock_spin(&clock_lock);
297 return ((high << 8) | low);
298 }
299
300 /*
301 * Wait "n" microseconds.
302 * Relies on timer 1 counting down from (i8254_freq / hz)
303 * Note: timer had better have been programmed before this is first used!
304 */
305 void
306 DELAY(int n)
307 {
308 int delta, prev_tick, tick, ticks_left;
309
310 #ifdef DELAYDEBUG
311 int getit_calls = 1;
312 int n1;
313 static int state = 0;
314 #endif
315
316 if (tsc_freq != 0 && !tsc_is_broken) {
317 uint64_t start, end, now;
318
319 sched_pin();
320 start = rdtsc();
321 end = start + (tsc_freq * n) / 1000000;
322 do {
323 cpu_spinwait();
324 now = rdtsc();
325 } while (now < end || (now > start && end < start));
326 sched_unpin();
327 return;
328 }
329 #ifdef DELAYDEBUG
330 if (state == 0) {
331 state = 1;
332 for (n1 = 1; n1 <= 10000000; n1 *= 10)
333 DELAY(n1);
334 state = 2;
335 }
336 if (state == 1)
337 printf("DELAY(%d)...", n);
338 #endif
339 /*
340 * Read the counter first, so that the rest of the setup overhead is
341 * counted. Guess the initial overhead is 20 usec (on most systems it
342 * takes about 1.5 usec for each of the i/o's in getit(). The loop
343 * takes about 6 usec on a 486/33 and 13 usec on a 386/20. The
344 * multiplications and divisions to scale the count take a while).
345 *
346 * However, if ddb is active then use a fake counter since reading
347 * the i8254 counter involves acquiring a lock. ddb must not do
348 * locking for many reasons, but it calls here for at least atkbd
349 * input.
350 */
351 #ifdef KDB
352 if (kdb_active)
353 prev_tick = 1;
354 else
355 #endif
356 prev_tick = getit();
357 n -= 0; /* XXX actually guess no initial overhead */
358 /*
359 * Calculate (n * (i8254_freq / 1e6)) without using floating point
360 * and without any avoidable overflows.
361 */
362 if (n <= 0)
363 ticks_left = 0;
364 else if (n < 256)
365 /*
366 * Use fixed point to avoid a slow division by 1000000.
367 * 39099 = 1193182 * 2^15 / 10^6 rounded to nearest.
368 * 2^15 is the first power of 2 that gives exact results
369 * for n between 0 and 256.
370 */
371 ticks_left = ((u_int)n * 39099 + (1 << 15) - 1) >> 15;
372 else
373 /*
374 * Don't bother using fixed point, although gcc-2.7.2
375 * generates particularly poor code for the long long
376 * division, since even the slow way will complete long
377 * before the delay is up (unless we're interrupted).
378 */
379 ticks_left = ((u_int)n * (long long)i8254_freq + 999999)
380 / 1000000;
381
382 while (ticks_left > 0) {
383 #ifdef KDB
384 if (kdb_active) {
385 inb(0x84);
386 tick = prev_tick - 1;
387 if (tick <= 0)
388 tick = i8254_max_count;
389 } else
390 #endif
391 tick = getit();
392 #ifdef DELAYDEBUG
393 ++getit_calls;
394 #endif
395 delta = prev_tick - tick;
396 prev_tick = tick;
397 if (delta < 0) {
398 delta += i8254_max_count;
399 /*
400 * Guard against i8254_max_count being wrong.
401 * This shouldn't happen in normal operation,
402 * but it may happen if set_i8254_freq() is
403 * traced.
404 */
405 if (delta < 0)
406 delta = 0;
407 }
408 ticks_left -= delta;
409 }
410 #ifdef DELAYDEBUG
411 if (state == 1)
412 printf(" %d calls to getit() at %d usec each\n",
413 getit_calls, (n + 5) / getit_calls);
414 #endif
415 }
416
417 static void
418 set_i8254_freq(u_int freq, int intr_freq)
419 {
420 int new_i8254_real_max_count;
421
422 i8254_timecounter.tc_frequency = freq;
423 mtx_lock_spin(&clock_lock);
424 i8254_freq = freq;
425 if (using_lapic_timer)
426 new_i8254_real_max_count = 0x10000;
427 else
428 new_i8254_real_max_count = TIMER_DIV(intr_freq);
429 if (new_i8254_real_max_count != i8254_real_max_count) {
430 i8254_real_max_count = new_i8254_real_max_count;
431 if (i8254_real_max_count == 0x10000)
432 i8254_max_count = 0xffff;
433 else
434 i8254_max_count = i8254_real_max_count;
435 outb(TIMER_MODE, TIMER_SEL0 | TIMER_RATEGEN | TIMER_16BIT);
436 outb(TIMER_CNTR0, i8254_real_max_count & 0xff);
437 outb(TIMER_CNTR0, i8254_real_max_count >> 8);
438 }
439 mtx_unlock_spin(&clock_lock);
440 }
441
442 static void
443 i8254_restore(void)
444 {
445
446 mtx_lock_spin(&clock_lock);
447 outb(TIMER_MODE, TIMER_SEL0 | TIMER_RATEGEN | TIMER_16BIT);
448 outb(TIMER_CNTR0, i8254_real_max_count & 0xff);
449 outb(TIMER_CNTR0, i8254_real_max_count >> 8);
450 mtx_unlock_spin(&clock_lock);
451 }
452
453 /* This is separate from startrtclock() so that it can be called early. */
454 void
455 i8254_init(void)
456 {
457
458 mtx_init(&clock_lock, "clk", NULL, MTX_SPIN | MTX_NOPROFILE);
459 set_i8254_freq(i8254_freq, hz);
460 }
461
462 void
463 startrtclock()
464 {
465
466 atrtc_start();
467
468 set_i8254_freq(i8254_freq, hz);
469 tc_init(&i8254_timecounter);
470
471 init_TSC();
472 }
473
474 /*
475 * Start both clocks running.
476 */
477 void
478 cpu_initclocks()
479 {
480
481 using_lapic_timer = lapic_setup_clock();
482 /*
483 * If we aren't using the local APIC timer to drive the kernel
484 * clocks, setup the interrupt handler for the 8254 timer 0 so
485 * that it can drive hardclock(). Otherwise, change the 8254
486 * timecounter to user a simpler algorithm.
487 */
488 if (!using_lapic_timer) {
489 intr_add_handler("clk", 0, (driver_filter_t *)clkintr, NULL,
490 NULL, INTR_TYPE_CLK, NULL);
491 i8254_intsrc = intr_lookup_source(0);
492 if (i8254_intsrc != NULL)
493 i8254_pending =
494 i8254_intsrc->is_pic->pic_source_pending;
495 } else {
496 i8254_timecounter.tc_get_timecount =
497 i8254_simple_get_timecount;
498 i8254_timecounter.tc_counter_mask = 0xffff;
499 set_i8254_freq(i8254_freq, hz);
500 }
501
502 /* Initialize RTC. */
503 atrtc_start();
504
505 /*
506 * If the separate statistics clock hasn't been explicility disabled
507 * and we aren't already using the local APIC timer to drive the
508 * kernel clocks, then setup the RTC to periodically interrupt to
509 * drive statclock() and profclock().
510 */
511 if (!using_lapic_timer) {
512 using_atrtc_timer = atrtc_setup_clock();
513 if (using_atrtc_timer) {
514 /* Enable periodic interrupts from the RTC. */
515 intr_add_handler("rtc", 8,
516 (driver_filter_t *)rtcintr, NULL, NULL,
517 INTR_TYPE_CLK, NULL);
518 atrtc_enable_intr();
519 } else {
520 profhz = hz;
521 if (hz < 128)
522 stathz = hz;
523 else
524 stathz = hz / (hz / 128);
525 }
526 }
527
528 init_TSC_tc();
529 }
530
531 void
532 cpu_startprofclock(void)
533 {
534
535 if (using_lapic_timer || !using_atrtc_timer)
536 return;
537 atrtc_rate(RTCSA_PROF);
538 psdiv = pscnt = psratio;
539 }
540
541 void
542 cpu_stopprofclock(void)
543 {
544
545 if (using_lapic_timer || !using_atrtc_timer)
546 return;
547 atrtc_rate(RTCSA_NOPROF);
548 psdiv = pscnt = 1;
549 }
550
551 static int
552 sysctl_machdep_i8254_freq(SYSCTL_HANDLER_ARGS)
553 {
554 int error;
555 u_int freq;
556
557 /*
558 * Use `i8254' instead of `timer' in external names because `timer'
559 * is is too generic. Should use it everywhere.
560 */
561 freq = i8254_freq;
562 error = sysctl_handle_int(oidp, &freq, 0, req);
563 if (error == 0 && req->newptr != NULL)
564 set_i8254_freq(freq, hz);
565 return (error);
566 }
567
568 SYSCTL_PROC(_machdep, OID_AUTO, i8254_freq, CTLTYPE_INT | CTLFLAG_RW,
569 0, sizeof(u_int), sysctl_machdep_i8254_freq, "IU", "");
570
571 static unsigned
572 i8254_simple_get_timecount(struct timecounter *tc)
573 {
574
575 return (i8254_max_count - getit());
576 }
577
578 static unsigned
579 i8254_get_timecount(struct timecounter *tc)
580 {
581 u_int count;
582 u_int high, low;
583 u_long rflags;
584
585 rflags = read_rflags();
586 mtx_lock_spin(&clock_lock);
587
588 /* Select timer0 and latch counter value. */
589 outb(TIMER_MODE, TIMER_SEL0 | TIMER_LATCH);
590
591 low = inb(TIMER_CNTR0);
592 high = inb(TIMER_CNTR0);
593 count = i8254_max_count - ((high << 8) | low);
594 if (count < i8254_lastcount ||
595 (!i8254_ticked && (clkintr_pending ||
596 ((count < 20 || (!(rflags & PSL_I) &&
597 count < i8254_max_count / 2u)) &&
598 i8254_pending != NULL && i8254_pending(i8254_intsrc))))) {
599 i8254_ticked = 1;
600 i8254_offset += i8254_max_count;
601 }
602 i8254_lastcount = count;
603 count += i8254_offset;
604 mtx_unlock_spin(&clock_lock);
605 return (count);
606 }
607
608 #ifdef DEV_ISA
609 /*
610 * Attach to the ISA PnP descriptors for the timer
611 */
612 static struct isa_pnp_id attimer_ids[] = {
613 { 0x0001d041 /* PNP0100 */, "AT timer" },
614 { 0 }
615 };
616
617 static int
618 attimer_probe(device_t dev)
619 {
620 int result;
621
622 result = ISA_PNP_PROBE(device_get_parent(dev), dev, attimer_ids);
623 if (result <= 0)
624 device_quiet(dev);
625 return(result);
626 }
627
628 static int
629 attimer_attach(device_t dev)
630 {
631 return(0);
632 }
633
634 static int
635 attimer_resume(device_t dev)
636 {
637
638 i8254_restore();
639 return(0);
640 }
641
642 static device_method_t attimer_methods[] = {
643 /* Device interface */
644 DEVMETHOD(device_probe, attimer_probe),
645 DEVMETHOD(device_attach, attimer_attach),
646 DEVMETHOD(device_detach, bus_generic_detach),
647 DEVMETHOD(device_shutdown, bus_generic_shutdown),
648 DEVMETHOD(device_suspend, bus_generic_suspend),
649 DEVMETHOD(device_resume, attimer_resume),
650 { 0, 0 }
651 };
652
653 static driver_t attimer_driver = {
654 "attimer",
655 attimer_methods,
656 1, /* no softc */
657 };
658
659 static devclass_t attimer_devclass;
660
661 DRIVER_MODULE(attimer, isa, attimer_driver, attimer_devclass, 0, 0);
662 DRIVER_MODULE(attimer, acpi, attimer_driver, attimer_devclass, 0, 0);
663
664 #endif /* DEV_ISA */
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