xref: /freebsd/sys/x86/isa/clock.c (revision bc3f5ec90bde2f3a5e4021d133c89793d68b8c73)
1 /*-
2  * Copyright (c) 1990 The Regents of the University of California.
3  * Copyright (c) 2010 Alexander Motin <mav@FreeBSD.org>
4  * All rights reserved.
5  *
6  * This code is derived from software contributed to Berkeley by
7  * William Jolitz and Don Ahn.
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
12  * 1. Redistributions of source code must retain the above copyright
13  *    notice, this list of conditions and the following disclaimer.
14  * 2. Redistributions in binary form must reproduce the above copyright
15  *    notice, this list of conditions and the following disclaimer in the
16  *    documentation and/or other materials provided with the distribution.
17  * 4. Neither the name of the University nor the names of its contributors
18  *    may be used to endorse or promote products derived from this software
19  *    without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  *
33  *	from: @(#)clock.c	7.2 (Berkeley) 5/12/91
34  */
35 
36 #include <sys/cdefs.h>
37 __FBSDID("$FreeBSD$");
38 
39 /*
40  * Routines to handle clock hardware.
41  */
42 
43 #include "opt_clock.h"
44 #include "opt_isa.h"
45 #include "opt_mca.h"
46 
47 #include <sys/param.h>
48 #include <sys/systm.h>
49 #include <sys/bus.h>
50 #include <sys/lock.h>
51 #include <sys/kdb.h>
52 #include <sys/mutex.h>
53 #include <sys/proc.h>
54 #include <sys/kernel.h>
55 #include <sys/module.h>
56 #include <sys/rman.h>
57 #include <sys/sched.h>
58 #include <sys/smp.h>
59 #include <sys/sysctl.h>
60 #include <sys/timeet.h>
61 #include <sys/timetc.h>
62 
63 #include <machine/clock.h>
64 #include <machine/cpu.h>
65 #include <machine/intr_machdep.h>
66 #include <machine/ppireg.h>
67 #include <machine/timerreg.h>
68 #include <x86/init.h>
69 
70 #ifdef PC98
71 #include <pc98/pc98/pc98_machdep.h>
72 #else
73 #include <isa/rtc.h>
74 #endif
75 #ifdef DEV_ISA
76 #ifdef PC98
77 #include <pc98/cbus/cbus.h>
78 #else
79 #include <isa/isareg.h>
80 #endif
81 #include <isa/isavar.h>
82 #endif
83 
84 #ifdef DEV_MCA
85 #include <i386/bios/mca_machdep.h>
86 #endif
87 
88 int	clkintr_pending;
89 #ifndef TIMER_FREQ
90 #ifdef PC98
91 #define TIMER_FREQ   2457600
92 #else
93 #define TIMER_FREQ   1193182
94 #endif
95 #endif
96 u_int	i8254_freq = TIMER_FREQ;
97 TUNABLE_INT("hw.i8254.freq", &i8254_freq);
98 int	i8254_max_count;
99 static int i8254_timecounter = 1;
100 
101 struct mtx clock_lock;
102 static	struct intsrc *i8254_intsrc;
103 static	uint16_t i8254_lastcount;
104 static	uint16_t i8254_offset;
105 static	int	(*i8254_pending)(struct intsrc *);
106 static	int	i8254_ticked;
107 
108 struct attimer_softc {
109 	int intr_en;
110 	int port_rid, intr_rid;
111 	struct resource *port_res;
112 	struct resource *intr_res;
113 #ifdef PC98
114 	int port_rid2;
115 	struct resource *port_res2;
116 #endif
117 	void *intr_handler;
118 	struct timecounter tc;
119 	struct eventtimer et;
120 	int		mode;
121 #define	MODE_STOP	0
122 #define	MODE_PERIODIC	1
123 #define	MODE_ONESHOT	2
124 	uint32_t	period;
125 };
126 static struct attimer_softc *attimer_sc = NULL;
127 
128 static int timer0_period = -2;
129 static int timer0_mode = 0xffff;
130 static int timer0_last = 0xffff;
131 
132 /* Values for timerX_state: */
133 #define	RELEASED	0
134 #define	RELEASE_PENDING	1
135 #define	ACQUIRED	2
136 #define	ACQUIRE_PENDING	3
137 
138 static	u_char	timer2_state;
139 
140 static	unsigned i8254_get_timecount(struct timecounter *tc);
141 static	void	set_i8254_freq(int mode, uint32_t period);
142 
143 void
144 clock_init(void)
145 {
146 	/* Init the clock lock */
147 	mtx_init(&clock_lock, "clk", NULL, MTX_SPIN | MTX_NOPROFILE);
148 	/* Init the clock in order to use DELAY */
149 	init_ops.early_clock_source_init();
150 }
151 
152 static int
153 clkintr(void *arg)
154 {
155 	struct attimer_softc *sc = (struct attimer_softc *)arg;
156 
157 	if (i8254_timecounter && sc->period != 0) {
158 		mtx_lock_spin(&clock_lock);
159 		if (i8254_ticked)
160 			i8254_ticked = 0;
161 		else {
162 			i8254_offset += i8254_max_count;
163 			i8254_lastcount = 0;
164 		}
165 		clkintr_pending = 0;
166 		mtx_unlock_spin(&clock_lock);
167 	}
168 
169 	if (sc && sc->et.et_active && sc->mode != MODE_STOP)
170 		sc->et.et_event_cb(&sc->et, sc->et.et_arg);
171 
172 #ifdef DEV_MCA
173 	/* Reset clock interrupt by asserting bit 7 of port 0x61 */
174 	if (MCA_system)
175 		outb(0x61, inb(0x61) | 0x80);
176 #endif
177 	return (FILTER_HANDLED);
178 }
179 
180 int
181 timer_spkr_acquire(void)
182 {
183 	int mode;
184 
185 #ifdef PC98
186 	mode = TIMER_SEL1 | TIMER_SQWAVE | TIMER_16BIT;
187 #else
188 	mode = TIMER_SEL2 | TIMER_SQWAVE | TIMER_16BIT;
189 #endif
190 
191 	if (timer2_state != RELEASED)
192 		return (-1);
193 	timer2_state = ACQUIRED;
194 
195 	/*
196 	 * This access to the timer registers is as atomic as possible
197 	 * because it is a single instruction.  We could do better if we
198 	 * knew the rate.  Use of splclock() limits glitches to 10-100us,
199 	 * and this is probably good enough for timer2, so we aren't as
200 	 * careful with it as with timer0.
201 	 */
202 #ifdef PC98
203 	outb(TIMER_MODE, TIMER_SEL1 | (mode & 0x3f));
204 #else
205 	outb(TIMER_MODE, TIMER_SEL2 | (mode & 0x3f));
206 #endif
207 	ppi_spkr_on();		/* enable counter2 output to speaker */
208 	return (0);
209 }
210 
211 int
212 timer_spkr_release(void)
213 {
214 
215 	if (timer2_state != ACQUIRED)
216 		return (-1);
217 	timer2_state = RELEASED;
218 #ifdef PC98
219 	outb(TIMER_MODE, TIMER_SEL1 | TIMER_SQWAVE | TIMER_16BIT);
220 #else
221 	outb(TIMER_MODE, TIMER_SEL2 | TIMER_SQWAVE | TIMER_16BIT);
222 #endif
223 	ppi_spkr_off();		/* disable counter2 output to speaker */
224 	return (0);
225 }
226 
227 void
228 timer_spkr_setfreq(int freq)
229 {
230 
231 	freq = i8254_freq / freq;
232 	mtx_lock_spin(&clock_lock);
233 #ifdef PC98
234 	outb(TIMER_CNTR1, freq & 0xff);
235 	outb(TIMER_CNTR1, freq >> 8);
236 #else
237 	outb(TIMER_CNTR2, freq & 0xff);
238 	outb(TIMER_CNTR2, freq >> 8);
239 #endif
240 	mtx_unlock_spin(&clock_lock);
241 }
242 
243 static int
244 getit(void)
245 {
246 	int high, low;
247 
248 	mtx_lock_spin(&clock_lock);
249 
250 	/* Select timer0 and latch counter value. */
251 	outb(TIMER_MODE, TIMER_SEL0 | TIMER_LATCH);
252 
253 	low = inb(TIMER_CNTR0);
254 	high = inb(TIMER_CNTR0);
255 
256 	mtx_unlock_spin(&clock_lock);
257 	return ((high << 8) | low);
258 }
259 
260 /*
261  * Wait "n" microseconds.
262  * Relies on timer 1 counting down from (i8254_freq / hz)
263  * Note: timer had better have been programmed before this is first used!
264  */
265 void
266 i8254_delay(int n)
267 {
268 	int delta, prev_tick, tick, ticks_left;
269 #ifdef DELAYDEBUG
270 	int getit_calls = 1;
271 	int n1;
272 	static int state = 0;
273 
274 	if (state == 0) {
275 		state = 1;
276 		for (n1 = 1; n1 <= 10000000; n1 *= 10)
277 			DELAY(n1);
278 		state = 2;
279 	}
280 	if (state == 1)
281 		printf("DELAY(%d)...", n);
282 #endif
283 	/*
284 	 * Read the counter first, so that the rest of the setup overhead is
285 	 * counted.  Guess the initial overhead is 20 usec (on most systems it
286 	 * takes about 1.5 usec for each of the i/o's in getit().  The loop
287 	 * takes about 6 usec on a 486/33 and 13 usec on a 386/20.  The
288 	 * multiplications and divisions to scale the count take a while).
289 	 *
290 	 * However, if ddb is active then use a fake counter since reading
291 	 * the i8254 counter involves acquiring a lock.  ddb must not do
292 	 * locking for many reasons, but it calls here for at least atkbd
293 	 * input.
294 	 */
295 #ifdef KDB
296 	if (kdb_active)
297 		prev_tick = 1;
298 	else
299 #endif
300 		prev_tick = getit();
301 	n -= 0;			/* XXX actually guess no initial overhead */
302 	/*
303 	 * Calculate (n * (i8254_freq / 1e6)) without using floating point
304 	 * and without any avoidable overflows.
305 	 */
306 	if (n <= 0)
307 		ticks_left = 0;
308 	else if (n < 256)
309 		/*
310 		 * Use fixed point to avoid a slow division by 1000000.
311 		 * 39099 = 1193182 * 2^15 / 10^6 rounded to nearest.
312 		 * 2^15 is the first power of 2 that gives exact results
313 		 * for n between 0 and 256.
314 		 */
315 		ticks_left = ((u_int)n * 39099 + (1 << 15) - 1) >> 15;
316 	else
317 		/*
318 		 * Don't bother using fixed point, although gcc-2.7.2
319 		 * generates particularly poor code for the long long
320 		 * division, since even the slow way will complete long
321 		 * before the delay is up (unless we're interrupted).
322 		 */
323 		ticks_left = ((u_int)n * (long long)i8254_freq + 999999)
324 			     / 1000000;
325 
326 	while (ticks_left > 0) {
327 #ifdef KDB
328 		if (kdb_active) {
329 #ifdef PC98
330 			outb(0x5f, 0);
331 #else
332 			inb(0x84);
333 #endif
334 			tick = prev_tick - 1;
335 			if (tick <= 0)
336 				tick = i8254_max_count;
337 		} else
338 #endif
339 			tick = getit();
340 #ifdef DELAYDEBUG
341 		++getit_calls;
342 #endif
343 		delta = prev_tick - tick;
344 		prev_tick = tick;
345 		if (delta < 0) {
346 			delta += i8254_max_count;
347 			/*
348 			 * Guard against i8254_max_count being wrong.
349 			 * This shouldn't happen in normal operation,
350 			 * but it may happen if set_i8254_freq() is
351 			 * traced.
352 			 */
353 			if (delta < 0)
354 				delta = 0;
355 		}
356 		ticks_left -= delta;
357 	}
358 #ifdef DELAYDEBUG
359 	if (state == 1)
360 		printf(" %d calls to getit() at %d usec each\n",
361 		       getit_calls, (n + 5) / getit_calls);
362 #endif
363 }
364 
365 static void
366 set_i8254_freq(int mode, uint32_t period)
367 {
368 	int new_count, new_mode;
369 
370 	mtx_lock_spin(&clock_lock);
371 	if (mode == MODE_STOP) {
372 		if (i8254_timecounter) {
373 			mode = MODE_PERIODIC;
374 			new_count = 0x10000;
375 		} else
376 			new_count = -1;
377 	} else {
378 		new_count = min(((uint64_t)i8254_freq * period +
379 		    0x80000000LLU) >> 32, 0x10000);
380 	}
381 	if (new_count == timer0_period)
382 		goto out;
383 	i8254_max_count = ((new_count & ~0xffff) != 0) ? 0xffff : new_count;
384 	timer0_period = (mode == MODE_PERIODIC) ? new_count : -1;
385 	switch (mode) {
386 	case MODE_STOP:
387 		new_mode = TIMER_SEL0 | TIMER_INTTC | TIMER_16BIT;
388 		outb(TIMER_MODE, new_mode);
389 		outb(TIMER_CNTR0, 0);
390 		outb(TIMER_CNTR0, 0);
391 		break;
392 	case MODE_PERIODIC:
393 		new_mode = TIMER_SEL0 | TIMER_RATEGEN | TIMER_16BIT;
394 		outb(TIMER_MODE, new_mode);
395 		outb(TIMER_CNTR0, new_count & 0xff);
396 		outb(TIMER_CNTR0, new_count >> 8);
397 		break;
398 	case MODE_ONESHOT:
399 		if (new_count < 256 && timer0_last < 256) {
400 			new_mode = TIMER_SEL0 | TIMER_INTTC | TIMER_LSB;
401 			if (new_mode != timer0_mode)
402 				outb(TIMER_MODE, new_mode);
403 			outb(TIMER_CNTR0, new_count & 0xff);
404 			break;
405 		}
406 		new_mode = TIMER_SEL0 | TIMER_INTTC | TIMER_16BIT;
407 		if (new_mode != timer0_mode)
408 			outb(TIMER_MODE, new_mode);
409 		outb(TIMER_CNTR0, new_count & 0xff);
410 		outb(TIMER_CNTR0, new_count >> 8);
411 		break;
412 	default:
413 		panic("set_i8254_freq: unknown operational mode");
414 	}
415 	timer0_mode = new_mode;
416 	timer0_last = new_count;
417 out:
418 	mtx_unlock_spin(&clock_lock);
419 }
420 
421 static void
422 i8254_restore(void)
423 {
424 
425 	timer0_period = -2;
426 	timer0_mode = 0xffff;
427 	timer0_last = 0xffff;
428 	if (attimer_sc != NULL)
429 		set_i8254_freq(attimer_sc->mode, attimer_sc->period);
430 	else
431 		set_i8254_freq(MODE_STOP, 0);
432 }
433 
434 #ifndef __amd64__
435 /*
436  * Restore all the timers non-atomically (XXX: should be atomically).
437  *
438  * This function is called from pmtimer_resume() to restore all the timers.
439  * This should not be necessary, but there are broken laptops that do not
440  * restore all the timers on resume. The APM spec was at best vague on the
441  * subject.
442  * pmtimer is used only with the old APM power management, and not with
443  * acpi, which is required for amd64, so skip it in that case.
444  */
445 void
446 timer_restore(void)
447 {
448 
449 	i8254_restore();		/* restore i8254_freq and hz */
450 #ifndef PC98
451 	atrtc_restore();		/* reenable RTC interrupts */
452 #endif
453 }
454 #endif
455 
456 /* This is separate from startrtclock() so that it can be called early. */
457 void
458 i8254_init(void)
459 {
460 
461 #ifdef PC98
462 	if (pc98_machine_type & M_8M)
463 		i8254_freq = 1996800L; /* 1.9968 MHz */
464 #endif
465 	set_i8254_freq(MODE_STOP, 0);
466 }
467 
468 void
469 startrtclock()
470 {
471 
472 	init_TSC();
473 }
474 
475 void
476 cpu_initclocks(void)
477 {
478 
479 	cpu_initclocks_bsp();
480 }
481 
482 static int
483 sysctl_machdep_i8254_freq(SYSCTL_HANDLER_ARGS)
484 {
485 	int error;
486 	u_int freq;
487 
488 	/*
489 	 * Use `i8254' instead of `timer' in external names because `timer'
490 	 * is too generic.  Should use it everywhere.
491 	 */
492 	freq = i8254_freq;
493 	error = sysctl_handle_int(oidp, &freq, 0, req);
494 	if (error == 0 && req->newptr != NULL) {
495 		i8254_freq = freq;
496 		if (attimer_sc != NULL) {
497 			set_i8254_freq(attimer_sc->mode, attimer_sc->period);
498 			attimer_sc->tc.tc_frequency = freq;
499 		} else {
500 			set_i8254_freq(MODE_STOP, 0);
501 		}
502 	}
503 	return (error);
504 }
505 
506 SYSCTL_PROC(_machdep, OID_AUTO, i8254_freq, CTLTYPE_INT | CTLFLAG_RW,
507     0, sizeof(u_int), sysctl_machdep_i8254_freq, "IU",
508     "i8254 timer frequency");
509 
510 static unsigned
511 i8254_get_timecount(struct timecounter *tc)
512 {
513 	device_t dev = (device_t)tc->tc_priv;
514 	struct attimer_softc *sc = device_get_softc(dev);
515 	register_t flags;
516 	uint16_t count;
517 	u_int high, low;
518 
519 	if (sc->period == 0)
520 		return (i8254_max_count - getit());
521 
522 #ifdef __amd64__
523 	flags = read_rflags();
524 #else
525 	flags = read_eflags();
526 #endif
527 	mtx_lock_spin(&clock_lock);
528 
529 	/* Select timer0 and latch counter value. */
530 	outb(TIMER_MODE, TIMER_SEL0 | TIMER_LATCH);
531 
532 	low = inb(TIMER_CNTR0);
533 	high = inb(TIMER_CNTR0);
534 	count = i8254_max_count - ((high << 8) | low);
535 	if (count < i8254_lastcount ||
536 	    (!i8254_ticked && (clkintr_pending ||
537 	    ((count < 20 || (!(flags & PSL_I) &&
538 	    count < i8254_max_count / 2u)) &&
539 	    i8254_pending != NULL && i8254_pending(i8254_intsrc))))) {
540 		i8254_ticked = 1;
541 		i8254_offset += i8254_max_count;
542 	}
543 	i8254_lastcount = count;
544 	count += i8254_offset;
545 	mtx_unlock_spin(&clock_lock);
546 	return (count);
547 }
548 
549 static int
550 attimer_start(struct eventtimer *et, sbintime_t first, sbintime_t period)
551 {
552 	device_t dev = (device_t)et->et_priv;
553 	struct attimer_softc *sc = device_get_softc(dev);
554 
555 	if (period != 0) {
556 		sc->mode = MODE_PERIODIC;
557 		sc->period = period;
558 	} else {
559 		sc->mode = MODE_ONESHOT;
560 		sc->period = first;
561 	}
562 	if (!sc->intr_en) {
563 		i8254_intsrc->is_pic->pic_enable_source(i8254_intsrc);
564 		sc->intr_en = 1;
565 	}
566 	set_i8254_freq(sc->mode, sc->period);
567 	return (0);
568 }
569 
570 static int
571 attimer_stop(struct eventtimer *et)
572 {
573 	device_t dev = (device_t)et->et_priv;
574 	struct attimer_softc *sc = device_get_softc(dev);
575 
576 	sc->mode = MODE_STOP;
577 	sc->period = 0;
578 	set_i8254_freq(sc->mode, sc->period);
579 	return (0);
580 }
581 
582 #ifdef DEV_ISA
583 /*
584  * Attach to the ISA PnP descriptors for the timer
585  */
586 static struct isa_pnp_id attimer_ids[] = {
587 	{ 0x0001d041 /* PNP0100 */, "AT timer" },
588 	{ 0 }
589 };
590 
591 #ifdef PC98
592 static void
593 pc98_alloc_resource(device_t dev)
594 {
595 	static bus_addr_t iat1[] = {0, 2, 4, 6};
596 	static bus_addr_t iat2[] = {0, 4};
597 	struct attimer_softc *sc;
598 
599 	sc = device_get_softc(dev);
600 
601 	sc->port_rid = 0;
602 	bus_set_resource(dev, SYS_RES_IOPORT, sc->port_rid, IO_TIMER1, 1);
603 	sc->port_res = isa_alloc_resourcev(dev, SYS_RES_IOPORT,
604 	    &sc->port_rid, iat1, 4, RF_ACTIVE);
605 	if (sc->port_res == NULL)
606 		device_printf(dev, "Warning: Couldn't map I/O.\n");
607 	else
608 		isa_load_resourcev(sc->port_res, iat1, 4);
609 
610 	sc->port_rid2 = 4;
611 	bus_set_resource(dev, SYS_RES_IOPORT, sc->port_rid2, TIMER_CNTR1, 1);
612 	sc->port_res2 = isa_alloc_resourcev(dev, SYS_RES_IOPORT,
613 	    &sc->port_rid2, iat2, 2, RF_ACTIVE);
614 	if (sc->port_res2 == NULL)
615 		device_printf(dev, "Warning: Couldn't map I/O.\n");
616 	else
617 		isa_load_resourcev(sc->port_res2, iat2, 2);
618 }
619 
620 static void
621 pc98_release_resource(device_t dev)
622 {
623 	struct attimer_softc *sc;
624 
625 	sc = device_get_softc(dev);
626 
627 	if (sc->port_res)
628 		bus_release_resource(dev, SYS_RES_IOPORT, sc->port_rid,
629 		    sc->port_res);
630 	if (sc->port_res2)
631 		bus_release_resource(dev, SYS_RES_IOPORT, sc->port_rid2,
632 		    sc->port_res2);
633 }
634 #endif
635 
636 static int
637 attimer_probe(device_t dev)
638 {
639 	int result;
640 
641 	result = ISA_PNP_PROBE(device_get_parent(dev), dev, attimer_ids);
642 	/* ENOENT means no PnP-ID, device is hinted. */
643 	if (result == ENOENT) {
644 		device_set_desc(dev, "AT timer");
645 #ifdef PC98
646 		/* To print resources correctly. */
647 		pc98_alloc_resource(dev);
648 		pc98_release_resource(dev);
649 #endif
650 		return (BUS_PROBE_LOW_PRIORITY);
651 	}
652 	return (result);
653 }
654 
655 static int
656 attimer_attach(device_t dev)
657 {
658 	struct attimer_softc *sc;
659 	u_long s;
660 	int i;
661 
662 	attimer_sc = sc = device_get_softc(dev);
663 	bzero(sc, sizeof(struct attimer_softc));
664 #ifdef PC98
665 	pc98_alloc_resource(dev);
666 #else
667 	if (!(sc->port_res = bus_alloc_resource(dev, SYS_RES_IOPORT,
668 	    &sc->port_rid, IO_TIMER1, IO_TIMER1 + 3, 4, RF_ACTIVE)))
669 		device_printf(dev,"Warning: Couldn't map I/O.\n");
670 #endif
671 	i8254_intsrc = intr_lookup_source(0);
672 	if (i8254_intsrc != NULL)
673 		i8254_pending = i8254_intsrc->is_pic->pic_source_pending;
674 	resource_int_value(device_get_name(dev), device_get_unit(dev),
675 	    "timecounter", &i8254_timecounter);
676 	set_i8254_freq(MODE_STOP, 0);
677 	if (i8254_timecounter) {
678 		sc->tc.tc_get_timecount = i8254_get_timecount;
679 		sc->tc.tc_counter_mask = 0xffff;
680 		sc->tc.tc_frequency = i8254_freq;
681 		sc->tc.tc_name = "i8254";
682 		sc->tc.tc_quality = 0;
683 		sc->tc.tc_priv = dev;
684 		tc_init(&sc->tc);
685 	}
686 	if (resource_int_value(device_get_name(dev), device_get_unit(dev),
687 	    "clock", &i) != 0 || i != 0) {
688 	    	sc->intr_rid = 0;
689 		while (bus_get_resource(dev, SYS_RES_IRQ, sc->intr_rid,
690 		    &s, NULL) == 0 && s != 0)
691 			sc->intr_rid++;
692 		if (!(sc->intr_res = bus_alloc_resource(dev, SYS_RES_IRQ,
693 		    &sc->intr_rid, 0, 0, 1, RF_ACTIVE))) {
694 			device_printf(dev,"Can't map interrupt.\n");
695 			return (0);
696 		}
697 		/* Dirty hack, to make bus_setup_intr to not enable source. */
698 		i8254_intsrc->is_handlers++;
699 		if ((bus_setup_intr(dev, sc->intr_res,
700 		    INTR_MPSAFE | INTR_TYPE_CLK,
701 		    (driver_filter_t *)clkintr, NULL,
702 		    sc, &sc->intr_handler))) {
703 			device_printf(dev, "Can't setup interrupt.\n");
704 			i8254_intsrc->is_handlers--;
705 			return (0);
706 		}
707 		i8254_intsrc->is_handlers--;
708 		i8254_intsrc->is_pic->pic_enable_intr(i8254_intsrc);
709 		sc->et.et_name = "i8254";
710 		sc->et.et_flags = ET_FLAGS_PERIODIC;
711 		if (!i8254_timecounter)
712 			sc->et.et_flags |= ET_FLAGS_ONESHOT;
713 		sc->et.et_quality = 100;
714 		sc->et.et_frequency = i8254_freq;
715 		sc->et.et_min_period = (0x0002LLU << 32) / i8254_freq;
716 		sc->et.et_max_period = (0xfffeLLU << 32) / i8254_freq;
717 		sc->et.et_start = attimer_start;
718 		sc->et.et_stop = attimer_stop;
719 		sc->et.et_priv = dev;
720 		et_register(&sc->et);
721 	}
722 	return(0);
723 }
724 
725 static int
726 attimer_resume(device_t dev)
727 {
728 
729 	i8254_restore();
730 	return (0);
731 }
732 
733 static device_method_t attimer_methods[] = {
734 	/* Device interface */
735 	DEVMETHOD(device_probe,		attimer_probe),
736 	DEVMETHOD(device_attach,	attimer_attach),
737 	DEVMETHOD(device_detach,	bus_generic_detach),
738 	DEVMETHOD(device_shutdown,	bus_generic_shutdown),
739 	DEVMETHOD(device_suspend,	bus_generic_suspend),
740 	DEVMETHOD(device_resume,	attimer_resume),
741 	{ 0, 0 }
742 };
743 
744 static driver_t attimer_driver = {
745 	"attimer",
746 	attimer_methods,
747 	sizeof(struct attimer_softc),
748 };
749 
750 static devclass_t attimer_devclass;
751 
752 DRIVER_MODULE(attimer, isa, attimer_driver, attimer_devclass, 0, 0);
753 DRIVER_MODULE(attimer, acpi, attimer_driver, attimer_devclass, 0, 0);
754 
755 #endif /* DEV_ISA */
756