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>
56 #include <sys/sysctl.h>
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>
68 #include <isa/isareg.h>
69 #include <isa/isavar.h>
72 #define TIMER_DIV(x) ((i8254_freq + (x) / 2) / (x))
77 int statclock_disable;
79 #define TIMER_FREQ 1193182
81 u_int i8254_freq = TIMER_FREQ;
82 TUNABLE_INT("hw.i8254.freq", &i8254_freq);
84 static int i8254_real_max_count;
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;
94 /* Values for timerX_state: */
96 #define RELEASE_PENDING 1
98 #define ACQUIRE_PENDING 3
100 static u_char timer2_state;
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);
106 static struct timecounter i8254_timecounter = {
107 i8254_get_timecount, /* get_timecount */
109 ~0u, /* counter_mask */
116 clkintr(struct trapframe *frame)
119 if (timecounter->tc_get_timecount == i8254_get_timecount) {
120 mtx_lock_spin(&clock_lock);
124 i8254_offset += i8254_max_count;
128 mtx_unlock_spin(&clock_lock);
130 KASSERT(!using_lapic_timer, ("clk interrupt enabled with lapic timer"));
131 hardclock(TRAPF_USERMODE(frame), TRAPF_PC(frame));
132 return (FILTER_HANDLED);
136 timer_spkr_acquire(void)
140 mode = TIMER_SEL2 | TIMER_SQWAVE | TIMER_16BIT;
142 if (timer2_state != RELEASED)
144 timer2_state = ACQUIRED;
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.
153 outb(TIMER_MODE, TIMER_SEL2 | (mode & 0x3f));
154 ppi_spkr_on(); /* enable counter2 output to speaker */
159 timer_spkr_release(void)
162 if (timer2_state != ACQUIRED)
164 timer2_state = RELEASED;
165 outb(TIMER_MODE, TIMER_SEL2 | TIMER_SQWAVE | TIMER_16BIT);
166 ppi_spkr_off(); /* disable counter2 output to speaker */
171 timer_spkr_setfreq(int freq)
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);
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.
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.
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.
203 rtcintr(struct trapframe *frame)
207 while (rtcin(RTC_INTR) & RTCIR_PERIOD) {
209 if (profprocs != 0) {
212 profclock(TRAPF_USERMODE(frame), TRAPF_PC(frame));
215 statclock(TRAPF_USERMODE(frame));
217 return(flag ? FILTER_HANDLED : FILTER_STRAY);
225 mtx_lock_spin(&clock_lock);
227 /* Select timer0 and latch counter value. */
228 outb(TIMER_MODE, TIMER_SEL0 | TIMER_LATCH);
230 low = inb(TIMER_CNTR0);
231 high = inb(TIMER_CNTR0);
233 mtx_unlock_spin(&clock_lock);
234 return ((high << 8) | low);
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!
245 int delta, prev_tick, tick, ticks_left;
250 static int state = 0;
253 if (tsc_freq != 0 && !tsc_is_broken) {
254 uint64_t start, end, now;
258 end = start + (tsc_freq * n) / 1000000;
262 } while (now < end || (now > start && end < start));
269 for (n1 = 1; n1 <= 10000000; n1 *= 10)
274 printf("DELAY(%d)...", n);
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).
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
294 n -= 0; /* XXX actually guess no initial overhead */
296 * Calculate (n * (i8254_freq / 1e6)) without using floating point
297 * and without any avoidable overflows.
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.
308 ticks_left = ((u_int)n * 39099 + (1 << 15) - 1) >> 15;
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).
316 ticks_left = ((u_int)n * (long long)i8254_freq + 999999)
319 while (ticks_left > 0) {
323 tick = prev_tick - 1;
325 tick = i8254_max_count;
332 delta = prev_tick - tick;
335 delta += i8254_max_count;
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
349 printf(" %d calls to getit() at %d usec each\n",
350 getit_calls, (n + 5) / getit_calls);
355 set_i8254_freq(u_int freq, int intr_freq)
357 int new_i8254_real_max_count;
359 i8254_timecounter.tc_frequency = freq;
360 mtx_lock_spin(&clock_lock);
362 if (using_lapic_timer)
363 new_i8254_real_max_count = 0x10000;
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;
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);
376 mtx_unlock_spin(&clock_lock);
379 /* This is separate from startrtclock() so that it can be called early. */
384 mtx_init(&clock_lock, "clk", NULL, MTX_SPIN | MTX_NOPROFILE);
385 set_i8254_freq(i8254_freq, hz);
394 set_i8254_freq(i8254_freq, hz);
395 tc_init(&i8254_timecounter);
401 * Start both clocks running.
408 using_lapic_timer = lapic_setup_clock();
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.
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)
421 i8254_intsrc->is_pic->pic_source_pending;
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);
429 /* Initialize RTC. */
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().
438 if (!statclock_disable && !using_lapic_timer) {
439 diag = rtcin(RTC_DIAG);
441 printf("RTC BIOS diagnostic error %b\n",
444 /* Setting stathz to nonzero early helps avoid races. */
445 stathz = RTC_NOPROFRATE;
446 profhz = RTC_PROFRATE;
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);
459 cpu_startprofclock(void)
462 if (using_lapic_timer)
464 atrtc_rate(RTCSA_PROF);
465 psdiv = pscnt = psratio;
469 cpu_stopprofclock(void)
472 if (using_lapic_timer)
474 atrtc_rate(RTCSA_NOPROF);
479 sysctl_machdep_i8254_freq(SYSCTL_HANDLER_ARGS)
485 * Use `i8254' instead of `timer' in external names because `timer'
486 * is is too generic. Should use it everywhere.
489 error = sysctl_handle_int(oidp, &freq, 0, req);
490 if (error == 0 && req->newptr != NULL)
491 set_i8254_freq(freq, hz);
495 SYSCTL_PROC(_machdep, OID_AUTO, i8254_freq, CTLTYPE_INT | CTLFLAG_RW,
496 0, sizeof(u_int), sysctl_machdep_i8254_freq, "IU", "");
499 i8254_simple_get_timecount(struct timecounter *tc)
502 return (i8254_max_count - getit());
506 i8254_get_timecount(struct timecounter *tc)
512 rflags = read_rflags();
513 mtx_lock_spin(&clock_lock);
515 /* Select timer0 and latch counter value. */
516 outb(TIMER_MODE, TIMER_SEL0 | TIMER_LATCH);
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))))) {
527 i8254_offset += i8254_max_count;
529 i8254_lastcount = count;
530 count += i8254_offset;
531 mtx_unlock_spin(&clock_lock);
537 * Attach to the ISA PnP descriptors for the timer
539 static struct isa_pnp_id attimer_ids[] = {
540 { 0x0001d041 /* PNP0100 */, "AT timer" },
545 attimer_probe(device_t dev)
549 result = ISA_PNP_PROBE(device_get_parent(dev), dev, attimer_ids);
556 attimer_attach(device_t dev)
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),
572 static driver_t attimer_driver = {
578 static devclass_t attimer_devclass;
580 DRIVER_MODULE(attimer, isa, attimer_driver, attimer_devclass, 0, 0);
581 DRIVER_MODULE(attimer, acpi, attimer_driver, attimer_devclass, 0, 0);