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 static int lapic_allclocks = 1;
88 TUNABLE_INT("machdep.lapic_allclocks", &lapic_allclocks);
90 struct mtx clock_lock;
91 static struct intsrc *i8254_intsrc;
92 static u_int32_t i8254_lastcount;
93 static u_int32_t i8254_offset;
94 static int (*i8254_pending)(struct intsrc *);
95 static int i8254_ticked;
96 static int using_atrtc_timer;
97 static enum lapic_clock using_lapic_timer = LAPIC_CLOCK_NONE;
99 /* Values for timerX_state: */
101 #define RELEASE_PENDING 1
103 #define ACQUIRE_PENDING 3
105 static u_char timer2_state;
107 static unsigned i8254_get_timecount(struct timecounter *tc);
108 static unsigned i8254_simple_get_timecount(struct timecounter *tc);
109 static void set_i8254_freq(u_int freq, int intr_freq);
111 static struct timecounter i8254_timecounter = {
112 i8254_get_timecount, /* get_timecount */
114 ~0u, /* counter_mask */
121 hardclockintr(struct trapframe *frame)
124 if (PCPU_GET(cpuid) == 0)
125 hardclock(TRAPF_USERMODE(frame), TRAPF_PC(frame));
127 hardclock_cpu(TRAPF_USERMODE(frame));
128 return (FILTER_HANDLED);
132 statclockintr(struct trapframe *frame)
135 profclockintr(frame);
136 statclock(TRAPF_USERMODE(frame));
137 return (FILTER_HANDLED);
141 profclockintr(struct trapframe *frame)
144 if (!using_atrtc_timer)
145 hardclockintr(frame);
147 profclock(TRAPF_USERMODE(frame), TRAPF_PC(frame));
148 return (FILTER_HANDLED);
152 clkintr(struct trapframe *frame)
155 if (timecounter->tc_get_timecount == i8254_get_timecount) {
156 mtx_lock_spin(&clock_lock);
160 i8254_offset += i8254_max_count;
164 mtx_unlock_spin(&clock_lock);
166 KASSERT(using_lapic_timer == LAPIC_CLOCK_NONE,
167 ("clk interrupt enabled with lapic timer"));
169 if (using_atrtc_timer) {
172 ipi_all_but_self(IPI_HARDCLOCK);
174 hardclockintr(frame);
180 ipi_all_but_self(IPI_STATCLOCK);
182 statclockintr(frame);
186 ipi_all_but_self(IPI_PROFCLOCK);
188 profclockintr(frame);
192 return (FILTER_HANDLED);
196 timer_spkr_acquire(void)
200 mode = TIMER_SEL2 | TIMER_SQWAVE | TIMER_16BIT;
202 if (timer2_state != RELEASED)
204 timer2_state = ACQUIRED;
207 * This access to the timer registers is as atomic as possible
208 * because it is a single instruction. We could do better if we
209 * knew the rate. Use of splclock() limits glitches to 10-100us,
210 * and this is probably good enough for timer2, so we aren't as
211 * careful with it as with timer0.
213 outb(TIMER_MODE, TIMER_SEL2 | (mode & 0x3f));
214 ppi_spkr_on(); /* enable counter2 output to speaker */
219 timer_spkr_release(void)
222 if (timer2_state != ACQUIRED)
224 timer2_state = RELEASED;
225 outb(TIMER_MODE, TIMER_SEL2 | TIMER_SQWAVE | TIMER_16BIT);
226 ppi_spkr_off(); /* disable counter2 output to speaker */
231 timer_spkr_setfreq(int freq)
234 freq = i8254_freq / freq;
235 mtx_lock_spin(&clock_lock);
236 outb(TIMER_CNTR2, freq & 0xff);
237 outb(TIMER_CNTR2, freq >> 8);
238 mtx_unlock_spin(&clock_lock);
242 * This routine receives statistical clock interrupts from the RTC.
243 * As explained above, these occur at 128 interrupts per second.
244 * When profiling, we receive interrupts at a rate of 1024 Hz.
246 * This does not actually add as much overhead as it sounds, because
247 * when the statistical clock is active, the hardclock driver no longer
248 * needs to keep (inaccurate) statistics on its own. This decouples
249 * statistics gathering from scheduling interrupts.
251 * The RTC chip requires that we read status register C (RTC_INTR)
252 * to acknowledge an interrupt, before it will generate the next one.
253 * Under high interrupt load, rtcintr() can be indefinitely delayed and
254 * the clock can tick immediately after the read from RTC_INTR. In this
255 * case, the mc146818A interrupt signal will not drop for long enough
256 * to register with the 8259 PIC. If an interrupt is missed, the stat
257 * clock will halt, considerably degrading system performance. This is
258 * why we use 'while' rather than a more straightforward 'if' below.
259 * Stat clock ticks can still be lost, causing minor loss of accuracy
260 * in the statistics, but the stat clock will no longer stop.
263 rtcintr(struct trapframe *frame)
267 while (rtcin(RTC_INTR) & RTCIR_PERIOD) {
273 ipi_all_but_self(IPI_STATCLOCK);
275 statclockintr(frame);
279 ipi_all_but_self(IPI_PROFCLOCK);
281 profclockintr(frame);
284 return(flag ? FILTER_HANDLED : FILTER_STRAY);
292 mtx_lock_spin(&clock_lock);
294 /* Select timer0 and latch counter value. */
295 outb(TIMER_MODE, TIMER_SEL0 | TIMER_LATCH);
297 low = inb(TIMER_CNTR0);
298 high = inb(TIMER_CNTR0);
300 mtx_unlock_spin(&clock_lock);
301 return ((high << 8) | low);
305 * Wait "n" microseconds.
306 * Relies on timer 1 counting down from (i8254_freq / hz)
307 * Note: timer had better have been programmed before this is first used!
312 int delta, prev_tick, tick, ticks_left;
317 static int state = 0;
320 if (tsc_freq != 0 && !tsc_is_broken) {
321 uint64_t start, end, now;
325 end = start + (tsc_freq * n) / 1000000;
329 } while (now < end || (now > start && end < start));
336 for (n1 = 1; n1 <= 10000000; n1 *= 10)
341 printf("DELAY(%d)...", n);
344 * Read the counter first, so that the rest of the setup overhead is
345 * counted. Guess the initial overhead is 20 usec (on most systems it
346 * takes about 1.5 usec for each of the i/o's in getit(). The loop
347 * takes about 6 usec on a 486/33 and 13 usec on a 386/20. The
348 * multiplications and divisions to scale the count take a while).
350 * However, if ddb is active then use a fake counter since reading
351 * the i8254 counter involves acquiring a lock. ddb must not do
352 * locking for many reasons, but it calls here for at least atkbd
361 n -= 0; /* XXX actually guess no initial overhead */
363 * Calculate (n * (i8254_freq / 1e6)) without using floating point
364 * and without any avoidable overflows.
370 * Use fixed point to avoid a slow division by 1000000.
371 * 39099 = 1193182 * 2^15 / 10^6 rounded to nearest.
372 * 2^15 is the first power of 2 that gives exact results
373 * for n between 0 and 256.
375 ticks_left = ((u_int)n * 39099 + (1 << 15) - 1) >> 15;
378 * Don't bother using fixed point, although gcc-2.7.2
379 * generates particularly poor code for the long long
380 * division, since even the slow way will complete long
381 * before the delay is up (unless we're interrupted).
383 ticks_left = ((u_int)n * (long long)i8254_freq + 999999)
386 while (ticks_left > 0) {
390 tick = prev_tick - 1;
392 tick = i8254_max_count;
399 delta = prev_tick - tick;
402 delta += i8254_max_count;
404 * Guard against i8254_max_count being wrong.
405 * This shouldn't happen in normal operation,
406 * but it may happen if set_i8254_freq() is
416 printf(" %d calls to getit() at %d usec each\n",
417 getit_calls, (n + 5) / getit_calls);
422 set_i8254_freq(u_int freq, int intr_freq)
424 int new_i8254_real_max_count;
426 i8254_timecounter.tc_frequency = freq;
427 mtx_lock_spin(&clock_lock);
429 if (using_lapic_timer != LAPIC_CLOCK_NONE)
430 new_i8254_real_max_count = 0x10000;
432 new_i8254_real_max_count = TIMER_DIV(intr_freq);
433 if (new_i8254_real_max_count != i8254_real_max_count) {
434 i8254_real_max_count = new_i8254_real_max_count;
435 if (i8254_real_max_count == 0x10000)
436 i8254_max_count = 0xffff;
438 i8254_max_count = i8254_real_max_count;
439 outb(TIMER_MODE, TIMER_SEL0 | TIMER_RATEGEN | TIMER_16BIT);
440 outb(TIMER_CNTR0, i8254_real_max_count & 0xff);
441 outb(TIMER_CNTR0, i8254_real_max_count >> 8);
443 mtx_unlock_spin(&clock_lock);
450 mtx_lock_spin(&clock_lock);
451 outb(TIMER_MODE, TIMER_SEL0 | TIMER_RATEGEN | TIMER_16BIT);
452 outb(TIMER_CNTR0, i8254_real_max_count & 0xff);
453 outb(TIMER_CNTR0, i8254_real_max_count >> 8);
454 mtx_unlock_spin(&clock_lock);
457 /* This is separate from startrtclock() so that it can be called early. */
462 mtx_init(&clock_lock, "clk", NULL, MTX_SPIN | MTX_NOPROFILE);
463 set_i8254_freq(i8254_freq, hz);
472 set_i8254_freq(i8254_freq, hz);
473 tc_init(&i8254_timecounter);
479 * Start both clocks running.
484 enum lapic_clock tlsca;
487 /* Initialize RTC. */
489 tasc = atrtc_setup_clock();
492 * If the atrtc successfully initialized and the users didn't force
493 * otherwise use the LAPIC in order to cater hardclock only, otherwise
494 * take in charge all the clock sources.
496 tlsca = (lapic_allclocks == 0 && tasc != 0) ? LAPIC_CLOCK_HARDCLOCK :
498 using_lapic_timer = lapic_setup_clock(tlsca);
501 * If we aren't using the local APIC timer to drive the kernel
502 * clocks, setup the interrupt handler for the 8254 timer 0 so
503 * that it can drive hardclock(). Otherwise, change the 8254
504 * timecounter to user a simpler algorithm.
506 if (using_lapic_timer == LAPIC_CLOCK_NONE) {
507 intr_add_handler("clk", 0, (driver_filter_t *)clkintr, NULL,
508 NULL, INTR_TYPE_CLK, NULL);
509 i8254_intsrc = intr_lookup_source(0);
510 if (i8254_intsrc != NULL)
512 i8254_intsrc->is_pic->pic_source_pending;
514 i8254_timecounter.tc_get_timecount =
515 i8254_simple_get_timecount;
516 i8254_timecounter.tc_counter_mask = 0xffff;
517 set_i8254_freq(i8254_freq, hz);
521 * If the separate statistics clock hasn't been explicility disabled
522 * and we aren't already using the local APIC timer to drive the
523 * kernel clocks, then setup the RTC to periodically interrupt to
524 * drive statclock() and profclock().
526 if (using_lapic_timer != LAPIC_CLOCK_ALL) {
527 using_atrtc_timer = tasc;
528 if (using_atrtc_timer) {
529 /* Enable periodic interrupts from the RTC. */
530 intr_add_handler("rtc", 8,
531 (driver_filter_t *)rtcintr, NULL, NULL,
532 INTR_TYPE_CLK, NULL);
539 stathz = hz / (hz / 128);
547 cpu_startprofclock(void)
550 if (using_lapic_timer == LAPIC_CLOCK_ALL || !using_atrtc_timer)
552 atrtc_rate(RTCSA_PROF);
553 psdiv = pscnt = psratio;
557 cpu_stopprofclock(void)
560 if (using_lapic_timer == LAPIC_CLOCK_ALL || !using_atrtc_timer)
562 atrtc_rate(RTCSA_NOPROF);
567 sysctl_machdep_i8254_freq(SYSCTL_HANDLER_ARGS)
573 * Use `i8254' instead of `timer' in external names because `timer'
574 * is is too generic. Should use it everywhere.
577 error = sysctl_handle_int(oidp, &freq, 0, req);
578 if (error == 0 && req->newptr != NULL)
579 set_i8254_freq(freq, hz);
583 SYSCTL_PROC(_machdep, OID_AUTO, i8254_freq, CTLTYPE_INT | CTLFLAG_RW,
584 0, sizeof(u_int), sysctl_machdep_i8254_freq, "IU", "");
587 i8254_simple_get_timecount(struct timecounter *tc)
590 return (i8254_max_count - getit());
594 i8254_get_timecount(struct timecounter *tc)
600 rflags = read_rflags();
601 mtx_lock_spin(&clock_lock);
603 /* Select timer0 and latch counter value. */
604 outb(TIMER_MODE, TIMER_SEL0 | TIMER_LATCH);
606 low = inb(TIMER_CNTR0);
607 high = inb(TIMER_CNTR0);
608 count = i8254_max_count - ((high << 8) | low);
609 if (count < i8254_lastcount ||
610 (!i8254_ticked && (clkintr_pending ||
611 ((count < 20 || (!(rflags & PSL_I) &&
612 count < i8254_max_count / 2u)) &&
613 i8254_pending != NULL && i8254_pending(i8254_intsrc))))) {
615 i8254_offset += i8254_max_count;
617 i8254_lastcount = count;
618 count += i8254_offset;
619 mtx_unlock_spin(&clock_lock);
625 * Attach to the ISA PnP descriptors for the timer
627 static struct isa_pnp_id attimer_ids[] = {
628 { 0x0001d041 /* PNP0100 */, "AT timer" },
633 attimer_probe(device_t dev)
637 result = ISA_PNP_PROBE(device_get_parent(dev), dev, attimer_ids);
644 attimer_attach(device_t dev)
650 attimer_resume(device_t dev)
657 static device_method_t attimer_methods[] = {
658 /* Device interface */
659 DEVMETHOD(device_probe, attimer_probe),
660 DEVMETHOD(device_attach, attimer_attach),
661 DEVMETHOD(device_detach, bus_generic_detach),
662 DEVMETHOD(device_shutdown, bus_generic_shutdown),
663 DEVMETHOD(device_suspend, bus_generic_suspend),
664 DEVMETHOD(device_resume, attimer_resume),
668 static driver_t attimer_driver = {
674 static devclass_t attimer_devclass;
676 DRIVER_MODULE(attimer, isa, attimer_driver, attimer_devclass, 0, 0);
677 DRIVER_MODULE(attimer, acpi, attimer_driver, attimer_devclass, 0, 0);