2 * Copyright (c) 1990 The Regents of the University of California.
5 * This code is derived from software contributed to Berkeley by
6 * William Jolitz and Don Ahn.
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
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.
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
32 * from: @(#)clock.c 7.2 (Berkeley) 5/12/91
35 #include <sys/cdefs.h>
36 __FBSDID("$FreeBSD$");
39 * Routines to handle clock hardware.
42 #include "opt_clock.h"
45 #include <sys/param.h>
46 #include <sys/systm.h>
50 #include <sys/mutex.h>
52 #include <sys/timetc.h>
53 #include <sys/kernel.h>
54 #include <sys/module.h>
55 #include <sys/sched.h>
57 #include <sys/sysctl.h>
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>
70 #include <isa/isareg.h>
71 #include <isa/isavar.h>
74 #define TIMER_DIV(x) ((i8254_freq + (x) / 2) / (x))
80 #define TIMER_FREQ 1193182
82 u_int i8254_freq = TIMER_FREQ;
83 TUNABLE_INT("hw.i8254.freq", &i8254_freq);
85 static int i8254_real_max_count;
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;
96 /* Values for timerX_state: */
98 #define RELEASE_PENDING 1
100 #define ACQUIRE_PENDING 3
102 static u_char timer2_state;
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);
108 static struct timecounter i8254_timecounter = {
109 i8254_get_timecount, /* get_timecount */
111 ~0u, /* counter_mask */
118 hardclockintr(struct trapframe *frame)
121 if (PCPU_GET(cpuid) == 0)
122 hardclock(TRAPF_USERMODE(frame), TRAPF_PC(frame));
124 hardclock_cpu(TRAPF_USERMODE(frame));
125 return (FILTER_HANDLED);
129 statclockintr(struct trapframe *frame)
132 profclockintr(frame);
133 statclock(TRAPF_USERMODE(frame));
134 return (FILTER_HANDLED);
138 profclockintr(struct trapframe *frame)
141 if (!using_atrtc_timer)
142 hardclockintr(frame);
144 profclock(TRAPF_USERMODE(frame), TRAPF_PC(frame));
145 return (FILTER_HANDLED);
149 clkintr(struct trapframe *frame)
152 if (timecounter->tc_get_timecount == i8254_get_timecount) {
153 mtx_lock_spin(&clock_lock);
157 i8254_offset += i8254_max_count;
161 mtx_unlock_spin(&clock_lock);
163 KASSERT(!using_lapic_timer, ("clk interrupt enabled with lapic timer"));
165 if (using_atrtc_timer) {
168 ipi_all_but_self(IPI_HARDCLOCK);
170 hardclockintr(frame);
176 ipi_all_but_self(IPI_STATCLOCK);
178 statclockintr(frame);
182 ipi_all_but_self(IPI_PROFCLOCK);
184 profclockintr(frame);
188 return (FILTER_HANDLED);
192 timer_spkr_acquire(void)
196 mode = TIMER_SEL2 | TIMER_SQWAVE | TIMER_16BIT;
198 if (timer2_state != RELEASED)
200 timer2_state = ACQUIRED;
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.
209 outb(TIMER_MODE, TIMER_SEL2 | (mode & 0x3f));
210 ppi_spkr_on(); /* enable counter2 output to speaker */
215 timer_spkr_release(void)
218 if (timer2_state != ACQUIRED)
220 timer2_state = RELEASED;
221 outb(TIMER_MODE, TIMER_SEL2 | TIMER_SQWAVE | TIMER_16BIT);
222 ppi_spkr_off(); /* disable counter2 output to speaker */
227 timer_spkr_setfreq(int freq)
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);
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.
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.
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.
259 rtcintr(struct trapframe *frame)
263 while (rtcin(RTC_INTR) & RTCIR_PERIOD) {
269 ipi_all_but_self(IPI_STATCLOCK);
271 statclockintr(frame);
275 ipi_all_but_self(IPI_PROFCLOCK);
277 profclockintr(frame);
280 return(flag ? FILTER_HANDLED : FILTER_STRAY);
288 mtx_lock_spin(&clock_lock);
290 /* Select timer0 and latch counter value. */
291 outb(TIMER_MODE, TIMER_SEL0 | TIMER_LATCH);
293 low = inb(TIMER_CNTR0);
294 high = inb(TIMER_CNTR0);
296 mtx_unlock_spin(&clock_lock);
297 return ((high << 8) | low);
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!
308 int delta, prev_tick, tick, ticks_left;
313 static int state = 0;
316 if (tsc_freq != 0 && !tsc_is_broken) {
317 uint64_t start, end, now;
321 end = start + (tsc_freq * n) / 1000000;
325 } while (now < end || (now > start && end < start));
332 for (n1 = 1; n1 <= 10000000; n1 *= 10)
337 printf("DELAY(%d)...", n);
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).
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
357 n -= 0; /* XXX actually guess no initial overhead */
359 * Calculate (n * (i8254_freq / 1e6)) without using floating point
360 * and without any avoidable overflows.
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.
371 ticks_left = ((u_int)n * 39099 + (1 << 15) - 1) >> 15;
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).
379 ticks_left = ((u_int)n * (long long)i8254_freq + 999999)
382 while (ticks_left > 0) {
386 tick = prev_tick - 1;
388 tick = i8254_max_count;
395 delta = prev_tick - tick;
398 delta += i8254_max_count;
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
412 printf(" %d calls to getit() at %d usec each\n",
413 getit_calls, (n + 5) / getit_calls);
418 set_i8254_freq(u_int freq, int intr_freq)
420 int new_i8254_real_max_count;
422 i8254_timecounter.tc_frequency = freq;
423 mtx_lock_spin(&clock_lock);
425 if (using_lapic_timer)
426 new_i8254_real_max_count = 0x10000;
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;
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);
439 mtx_unlock_spin(&clock_lock);
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);
453 /* This is separate from startrtclock() so that it can be called early. */
458 mtx_init(&clock_lock, "clk", NULL, MTX_SPIN | MTX_NOPROFILE);
459 set_i8254_freq(i8254_freq, hz);
468 set_i8254_freq(i8254_freq, hz);
469 tc_init(&i8254_timecounter);
475 * Start both clocks running.
481 using_lapic_timer = lapic_setup_clock();
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.
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)
494 i8254_intsrc->is_pic->pic_source_pending;
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);
502 /* Initialize RTC. */
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().
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);
524 stathz = hz / (hz / 128);
532 cpu_startprofclock(void)
535 if (using_lapic_timer || !using_atrtc_timer)
537 atrtc_rate(RTCSA_PROF);
538 psdiv = pscnt = psratio;
542 cpu_stopprofclock(void)
545 if (using_lapic_timer || !using_atrtc_timer)
547 atrtc_rate(RTCSA_NOPROF);
552 sysctl_machdep_i8254_freq(SYSCTL_HANDLER_ARGS)
558 * Use `i8254' instead of `timer' in external names because `timer'
559 * is is too generic. Should use it everywhere.
562 error = sysctl_handle_int(oidp, &freq, 0, req);
563 if (error == 0 && req->newptr != NULL)
564 set_i8254_freq(freq, hz);
568 SYSCTL_PROC(_machdep, OID_AUTO, i8254_freq, CTLTYPE_INT | CTLFLAG_RW,
569 0, sizeof(u_int), sysctl_machdep_i8254_freq, "IU", "");
572 i8254_simple_get_timecount(struct timecounter *tc)
575 return (i8254_max_count - getit());
579 i8254_get_timecount(struct timecounter *tc)
585 rflags = read_rflags();
586 mtx_lock_spin(&clock_lock);
588 /* Select timer0 and latch counter value. */
589 outb(TIMER_MODE, TIMER_SEL0 | TIMER_LATCH);
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))))) {
600 i8254_offset += i8254_max_count;
602 i8254_lastcount = count;
603 count += i8254_offset;
604 mtx_unlock_spin(&clock_lock);
610 * Attach to the ISA PnP descriptors for the timer
612 static struct isa_pnp_id attimer_ids[] = {
613 { 0x0001d041 /* PNP0100 */, "AT timer" },
618 attimer_probe(device_t dev)
622 result = ISA_PNP_PROBE(device_get_parent(dev), dev, attimer_ids);
629 attimer_attach(device_t dev)
635 attimer_resume(device_t dev)
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),
653 static driver_t attimer_driver = {
659 static devclass_t attimer_devclass;
661 DRIVER_MODULE(attimer, isa, attimer_driver, attimer_devclass, 0, 0);
662 DRIVER_MODULE(attimer, acpi, attimer_driver, attimer_devclass, 0, 0);