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: src/sys/amd64/isa/clock.c,v 1.243 2008/04/22 19:38:27 phk Exp $");
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/sysctl.h>
57
58 #include <machine/clock.h>
59 #include <machine/cpu.h>
60 #include <machine/intr_machdep.h>
61 #include <machine/md_var.h>
62 #include <machine/apicvar.h>
63 #include <machine/ppireg.h>
64 #include <machine/timerreg.h>
65
66 #include <isa/rtc.h>
67 #ifdef DEV_ISA
68 #include <isa/isareg.h>
69 #include <isa/isavar.h>
70 #endif
71
72 #define TIMER_DIV(x) ((i8254_freq + (x) / 2) / (x))
73
74 int clkintr_pending;
75 static int pscnt = 1;
76 static int psdiv = 1;
77 int statclock_disable;
78 #ifndef TIMER_FREQ
79 #define TIMER_FREQ 1193182
80 #endif
81 u_int i8254_freq = TIMER_FREQ;
82 TUNABLE_INT("hw.i8254.freq", &i8254_freq);
83 int i8254_max_count;
84 static int i8254_real_max_count;
85
86 struct mtx clock_lock;
87 static struct intsrc *i8254_intsrc;
88 static u_int32_t i8254_lastcount;
89 static u_int32_t i8254_offset;
90 static int (*i8254_pending)(struct intsrc *);
91 static int i8254_ticked;
92 static int using_lapic_timer;
93
94 /* Values for timerX_state: */
95 #define RELEASED 0
96 #define RELEASE_PENDING 1
97 #define ACQUIRED 2
98 #define ACQUIRE_PENDING 3
99
100 static u_char timer2_state;
101
102 static unsigned i8254_get_timecount(struct timecounter *tc);
103 static unsigned i8254_simple_get_timecount(struct timecounter *tc);
104 static void set_i8254_freq(u_int freq, int intr_freq);
105
106 static struct timecounter i8254_timecounter = {
107 i8254_get_timecount, /* get_timecount */
108 0, /* no poll_pps */
109 ~0u, /* counter_mask */
110 0, /* frequency */
111 "i8254", /* name */
112 0 /* quality */
113 };
114
115 static int
116 clkintr(struct trapframe *frame)
117 {
118
119 if (timecounter->tc_get_timecount == i8254_get_timecount) {
120 mtx_lock_spin(&clock_lock);
121 if (i8254_ticked)
122 i8254_ticked = 0;
123 else {
124 i8254_offset += i8254_max_count;
125 i8254_lastcount = 0;
126 }
127 clkintr_pending = 0;
128 mtx_unlock_spin(&clock_lock);
129 }
130 KASSERT(!using_lapic_timer, ("clk interrupt enabled with lapic timer"));
131 hardclock(TRAPF_USERMODE(frame), TRAPF_PC(frame));
132 return (FILTER_HANDLED);
133 }
134
135 int
136 timer_spkr_acquire(void)
137 {
138 int mode;
139
140 mode = TIMER_SEL2 | TIMER_SQWAVE | TIMER_16BIT;
141
142 if (timer2_state != RELEASED)
143 return (-1);
144 timer2_state = ACQUIRED;
145
146 /*
147 * This access to the timer registers is as atomic as possible
148 * because it is a single instruction. We could do better if we
149 * knew the rate. Use of splclock() limits glitches to 10-100us,
150 * and this is probably good enough for timer2, so we aren't as
151 * careful with it as with timer0.
152 */
153 outb(TIMER_MODE, TIMER_SEL2 | (mode & 0x3f));
154 ppi_spkr_on(); /* enable counter2 output to speaker */
155 return (0);
156 }
157
158 int
159 timer_spkr_release(void)
160 {
161
162 if (timer2_state != ACQUIRED)
163 return (-1);
164 timer2_state = RELEASED;
165 outb(TIMER_MODE, TIMER_SEL2 | TIMER_SQWAVE | TIMER_16BIT);
166 ppi_spkr_off(); /* disable counter2 output to speaker */
167 return (0);
168 }
169
170 void
171 timer_spkr_setfreq(int freq)
172 {
173
174 freq = i8254_freq / freq;
175 mtx_lock_spin(&clock_lock);
176 outb(TIMER_CNTR2, freq & 0xff);
177 outb(TIMER_CNTR2, freq >> 8);
178 mtx_unlock_spin(&clock_lock);
179 }
180
181 /*
182 * This routine receives statistical clock interrupts from the RTC.
183 * As explained above, these occur at 128 interrupts per second.
184 * When profiling, we receive interrupts at a rate of 1024 Hz.
185 *
186 * This does not actually add as much overhead as it sounds, because
187 * when the statistical clock is active, the hardclock driver no longer
188 * needs to keep (inaccurate) statistics on its own. This decouples
189 * statistics gathering from scheduling interrupts.
190 *
191 * The RTC chip requires that we read status register C (RTC_INTR)
192 * to acknowledge an interrupt, before it will generate the next one.
193 * Under high interrupt load, rtcintr() can be indefinitely delayed and
194 * the clock can tick immediately after the read from RTC_INTR. In this
195 * case, the mc146818A interrupt signal will not drop for long enough
196 * to register with the 8259 PIC. If an interrupt is missed, the stat
197 * clock will halt, considerably degrading system performance. This is
198 * why we use 'while' rather than a more straightforward 'if' below.
199 * Stat clock ticks can still be lost, causing minor loss of accuracy
200 * in the statistics, but the stat clock will no longer stop.
201 */
202 static int
203 rtcintr(struct trapframe *frame)
204 {
205 int flag = 0;
206
207 while (rtcin(RTC_INTR) & RTCIR_PERIOD) {
208 flag = 1;
209 if (profprocs != 0) {
210 if (--pscnt == 0)
211 pscnt = psdiv;
212 profclock(TRAPF_USERMODE(frame), TRAPF_PC(frame));
213 }
214 if (pscnt == psdiv)
215 statclock(TRAPF_USERMODE(frame));
216 }
217 return(flag ? FILTER_HANDLED : FILTER_STRAY);
218 }
219
220 static int
221 getit(void)
222 {
223 int high, low;
224
225 mtx_lock_spin(&clock_lock);
226
227 /* Select timer0 and latch counter value. */
228 outb(TIMER_MODE, TIMER_SEL0 | TIMER_LATCH);
229
230 low = inb(TIMER_CNTR0);
231 high = inb(TIMER_CNTR0);
232
233 mtx_unlock_spin(&clock_lock);
234 return ((high << 8) | low);
235 }
236
237 /*
238 * Wait "n" microseconds.
239 * Relies on timer 1 counting down from (i8254_freq / hz)
240 * Note: timer had better have been programmed before this is first used!
241 */
242 void
243 DELAY(int n)
244 {
245 int delta, prev_tick, tick, ticks_left;
246
247 #ifdef DELAYDEBUG
248 int getit_calls = 1;
249 int n1;
250 static int state = 0;
251 #endif
252
253 if (tsc_freq != 0 && !tsc_is_broken) {
254 uint64_t start, end, now;
255
256 sched_pin();
257 start = rdtsc();
258 end = start + (tsc_freq * n) / 1000000;
259 do {
260 cpu_spinwait();
261 now = rdtsc();
262 } while (now < end || (now > start && end < start));
263 sched_unpin();
264 return;
265 }
266 #ifdef DELAYDEBUG
267 if (state == 0) {
268 state = 1;
269 for (n1 = 1; n1 <= 10000000; n1 *= 10)
270 DELAY(n1);
271 state = 2;
272 }
273 if (state == 1)
274 printf("DELAY(%d)...", n);
275 #endif
276 /*
277 * Read the counter first, so that the rest of the setup overhead is
278 * counted. Guess the initial overhead is 20 usec (on most systems it
279 * takes about 1.5 usec for each of the i/o's in getit(). The loop
280 * takes about 6 usec on a 486/33 and 13 usec on a 386/20. The
281 * multiplications and divisions to scale the count take a while).
282 *
283 * However, if ddb is active then use a fake counter since reading
284 * the i8254 counter involves acquiring a lock. ddb must not do
285 * locking for many reasons, but it calls here for at least atkbd
286 * input.
287 */
288 #ifdef KDB
289 if (kdb_active)
290 prev_tick = 1;
291 else
292 #endif
293 prev_tick = getit();
294 n -= 0; /* XXX actually guess no initial overhead */
295 /*
296 * Calculate (n * (i8254_freq / 1e6)) without using floating point
297 * and without any avoidable overflows.
298 */
299 if (n <= 0)
300 ticks_left = 0;
301 else if (n < 256)
302 /*
303 * Use fixed point to avoid a slow division by 1000000.
304 * 39099 = 1193182 * 2^15 / 10^6 rounded to nearest.
305 * 2^15 is the first power of 2 that gives exact results
306 * for n between 0 and 256.
307 */
308 ticks_left = ((u_int)n * 39099 + (1 << 15) - 1) >> 15;
309 else
310 /*
311 * Don't bother using fixed point, although gcc-2.7.2
312 * generates particularly poor code for the long long
313 * division, since even the slow way will complete long
314 * before the delay is up (unless we're interrupted).
315 */
316 ticks_left = ((u_int)n * (long long)i8254_freq + 999999)
317 / 1000000;
318
319 while (ticks_left > 0) {
320 #ifdef KDB
321 if (kdb_active) {
322 inb(0x84);
323 tick = prev_tick - 1;
324 if (tick <= 0)
325 tick = i8254_max_count;
326 } else
327 #endif
328 tick = getit();
329 #ifdef DELAYDEBUG
330 ++getit_calls;
331 #endif
332 delta = prev_tick - tick;
333 prev_tick = tick;
334 if (delta < 0) {
335 delta += i8254_max_count;
336 /*
337 * Guard against i8254_max_count being wrong.
338 * This shouldn't happen in normal operation,
339 * but it may happen if set_i8254_freq() is
340 * traced.
341 */
342 if (delta < 0)
343 delta = 0;
344 }
345 ticks_left -= delta;
346 }
347 #ifdef DELAYDEBUG
348 if (state == 1)
349 printf(" %d calls to getit() at %d usec each\n",
350 getit_calls, (n + 5) / getit_calls);
351 #endif
352 }
353
354 static void
355 set_i8254_freq(u_int freq, int intr_freq)
356 {
357 int new_i8254_real_max_count;
358
359 i8254_timecounter.tc_frequency = freq;
360 mtx_lock_spin(&clock_lock);
361 i8254_freq = freq;
362 if (using_lapic_timer)
363 new_i8254_real_max_count = 0x10000;
364 else
365 new_i8254_real_max_count = TIMER_DIV(intr_freq);
366 if (new_i8254_real_max_count != i8254_real_max_count) {
367 i8254_real_max_count = new_i8254_real_max_count;
368 if (i8254_real_max_count == 0x10000)
369 i8254_max_count = 0xffff;
370 else
371 i8254_max_count = i8254_real_max_count;
372 outb(TIMER_MODE, TIMER_SEL0 | TIMER_RATEGEN | TIMER_16BIT);
373 outb(TIMER_CNTR0, i8254_real_max_count & 0xff);
374 outb(TIMER_CNTR0, i8254_real_max_count >> 8);
375 }
376 mtx_unlock_spin(&clock_lock);
377 }
378
379 /* This is separate from startrtclock() so that it can be called early. */
380 void
381 i8254_init(void)
382 {
383
384 mtx_init(&clock_lock, "clk", NULL, MTX_SPIN | MTX_NOPROFILE);
385 set_i8254_freq(i8254_freq, hz);
386 }
387
388 void
389 startrtclock()
390 {
391
392 atrtc_start();
393
394 set_i8254_freq(i8254_freq, hz);
395 tc_init(&i8254_timecounter);
396
397 init_TSC();
398 }
399
400 /*
401 * Start both clocks running.
402 */
403 void
404 cpu_initclocks()
405 {
406 int diag;
407
408 using_lapic_timer = lapic_setup_clock();
409 /*
410 * If we aren't using the local APIC timer to drive the kernel
411 * clocks, setup the interrupt handler for the 8254 timer 0 so
412 * that it can drive hardclock(). Otherwise, change the 8254
413 * timecounter to user a simpler algorithm.
414 */
415 if (!using_lapic_timer) {
416 intr_add_handler("clk", 0, (driver_filter_t *)clkintr, NULL,
417 NULL, INTR_TYPE_CLK, NULL);
418 i8254_intsrc = intr_lookup_source(0);
419 if (i8254_intsrc != NULL)
420 i8254_pending =
421 i8254_intsrc->is_pic->pic_source_pending;
422 } else {
423 i8254_timecounter.tc_get_timecount =
424 i8254_simple_get_timecount;
425 i8254_timecounter.tc_counter_mask = 0xffff;
426 set_i8254_freq(i8254_freq, hz);
427 }
428
429 /* Initialize RTC. */
430 atrtc_start();
431
432 /*
433 * If the separate statistics clock hasn't been explicility disabled
434 * and we aren't already using the local APIC timer to drive the
435 * kernel clocks, then setup the RTC to periodically interrupt to
436 * drive statclock() and profclock().
437 */
438 if (!statclock_disable && !using_lapic_timer) {
439 diag = rtcin(RTC_DIAG);
440 if (diag != 0)
441 printf("RTC BIOS diagnostic error %b\n",
442 diag, RTCDG_BITS);
443
444 /* Setting stathz to nonzero early helps avoid races. */
445 stathz = RTC_NOPROFRATE;
446 profhz = RTC_PROFRATE;
447
448 /* Enable periodic interrupts from the RTC. */
449 intr_add_handler("rtc", 8,
450 (driver_filter_t *)rtcintr, NULL, NULL,
451 INTR_TYPE_CLK, NULL);
452 atrtc_enable_intr();
453 }
454
455 init_TSC_tc();
456 }
457
458 void
459 cpu_startprofclock(void)
460 {
461
462 if (using_lapic_timer)
463 return;
464 atrtc_rate(RTCSA_PROF);
465 psdiv = pscnt = psratio;
466 }
467
468 void
469 cpu_stopprofclock(void)
470 {
471
472 if (using_lapic_timer)
473 return;
474 atrtc_rate(RTCSA_NOPROF);
475 psdiv = pscnt = 1;
476 }
477
478 static int
479 sysctl_machdep_i8254_freq(SYSCTL_HANDLER_ARGS)
480 {
481 int error;
482 u_int freq;
483
484 /*
485 * Use `i8254' instead of `timer' in external names because `timer'
486 * is is too generic. Should use it everywhere.
487 */
488 freq = i8254_freq;
489 error = sysctl_handle_int(oidp, &freq, 0, req);
490 if (error == 0 && req->newptr != NULL)
491 set_i8254_freq(freq, hz);
492 return (error);
493 }
494
495 SYSCTL_PROC(_machdep, OID_AUTO, i8254_freq, CTLTYPE_INT | CTLFLAG_RW,
496 0, sizeof(u_int), sysctl_machdep_i8254_freq, "IU", "");
497
498 static unsigned
499 i8254_simple_get_timecount(struct timecounter *tc)
500 {
501
502 return (i8254_max_count - getit());
503 }
504
505 static unsigned
506 i8254_get_timecount(struct timecounter *tc)
507 {
508 u_int count;
509 u_int high, low;
510 u_long rflags;
511
512 rflags = read_rflags();
513 mtx_lock_spin(&clock_lock);
514
515 /* Select timer0 and latch counter value. */
516 outb(TIMER_MODE, TIMER_SEL0 | TIMER_LATCH);
517
518 low = inb(TIMER_CNTR0);
519 high = inb(TIMER_CNTR0);
520 count = i8254_max_count - ((high << 8) | low);
521 if (count < i8254_lastcount ||
522 (!i8254_ticked && (clkintr_pending ||
523 ((count < 20 || (!(rflags & PSL_I) &&
524 count < i8254_max_count / 2u)) &&
525 i8254_pending != NULL && i8254_pending(i8254_intsrc))))) {
526 i8254_ticked = 1;
527 i8254_offset += i8254_max_count;
528 }
529 i8254_lastcount = count;
530 count += i8254_offset;
531 mtx_unlock_spin(&clock_lock);
532 return (count);
533 }
534
535 #ifdef DEV_ISA
536 /*
537 * Attach to the ISA PnP descriptors for the timer
538 */
539 static struct isa_pnp_id attimer_ids[] = {
540 { 0x0001d041 /* PNP0100 */, "AT timer" },
541 { 0 }
542 };
543
544 static int
545 attimer_probe(device_t dev)
546 {
547 int result;
548
549 result = ISA_PNP_PROBE(device_get_parent(dev), dev, attimer_ids);
550 if (result <= 0)
551 device_quiet(dev);
552 return(result);
553 }
554
555 static int
556 attimer_attach(device_t dev)
557 {
558 return(0);
559 }
560
561 static device_method_t attimer_methods[] = {
562 /* Device interface */
563 DEVMETHOD(device_probe, attimer_probe),
564 DEVMETHOD(device_attach, attimer_attach),
565 DEVMETHOD(device_detach, bus_generic_detach),
566 DEVMETHOD(device_shutdown, bus_generic_shutdown),
567 DEVMETHOD(device_suspend, bus_generic_suspend),
568 DEVMETHOD(device_resume, bus_generic_resume),
569 { 0, 0 }
570 };
571
572 static driver_t attimer_driver = {
573 "attimer",
574 attimer_methods,
575 1, /* no softc */
576 };
577
578 static devclass_t attimer_devclass;
579
580 DRIVER_MODULE(attimer, isa, attimer_driver, attimer_devclass, 0, 0);
581 DRIVER_MODULE(attimer, acpi, attimer_driver, attimer_devclass, 0, 0);
582
583 #endif /* DEV_ISA */
584 Cache object: 8df0c62add228a80838e1e52f1fc3b66
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