timer.c 15.7 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135
/* -*- linux-c -*-
 * linux/kernel/ipipe/timer.c
 *
 * Copyright (C) 2012 Gilles Chanteperdrix
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, Inc., 675 Mass Ave, Cambridge MA 02139,
 * USA; either version 2 of the License, or (at your option) any later
 * version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 * I-pipe timer request interface.
 */
#include <linux/ipipe.h>
#include <linux/percpu.h>
#include <linux/irqdesc.h>
#include <linux/cpumask.h>
#include <linux/spinlock.h>
#include <linux/ipipe_tickdev.h>
#include <linux/interrupt.h>
#include <linux/export.h>

unsigned long __ipipe_hrtimer_freq;

static LIST_HEAD(timers);
static IPIPE_DEFINE_SPINLOCK(lock);

static DEFINE_PER_CPU(struct ipipe_timer *, percpu_timer);

/*
 * Default request method: switch to oneshot mode if supported.
 */
static void ipipe_timer_default_request(struct ipipe_timer *timer, int steal)
{
	struct clock_event_device *evtdev = timer->host_timer;

	if (!(evtdev->features & CLOCK_EVT_FEAT_ONESHOT))
		return;

	if (clockevent_state_oneshot(evtdev) ||
		clockevent_state_oneshot_stopped(evtdev))
		timer->orig_mode = CLOCK_EVT_MODE_ONESHOT;
	else {
		if (clockevent_state_periodic(evtdev))
			timer->orig_mode = CLOCK_EVT_MODE_PERIODIC;
		else if (clockevent_state_shutdown(evtdev))
			timer->orig_mode = CLOCK_EVT_MODE_SHUTDOWN;
		else
			timer->orig_mode = CLOCK_EVT_MODE_UNUSED;
		evtdev->set_state_oneshot(evtdev);
		evtdev->set_next_event(timer->freq / HZ, evtdev);
	}
}

/*
 * Default release method: return the timer to the mode it had when
 * starting.
 */
static void ipipe_timer_default_release(struct ipipe_timer *timer)
{
	struct clock_event_device *evtdev = timer->host_timer;

	switch (timer->orig_mode) {
	case CLOCK_EVT_MODE_SHUTDOWN:
		evtdev->set_state_shutdown(evtdev);
		break;
	case CLOCK_EVT_MODE_PERIODIC:
		evtdev->set_state_periodic(evtdev);
	case CLOCK_EVT_MODE_ONESHOT:
		evtdev->set_next_event(timer->freq / HZ, evtdev);
		break;
	}
}

static int get_dev_mode(struct clock_event_device *evtdev)
{
	if (clockevent_state_oneshot(evtdev) ||
		clockevent_state_oneshot_stopped(evtdev))
		return CLOCK_EVT_MODE_ONESHOT;

	if (clockevent_state_periodic(evtdev))
		return CLOCK_EVT_MODE_PERIODIC;

	if (clockevent_state_shutdown(evtdev))
		return CLOCK_EVT_MODE_SHUTDOWN;

	return CLOCK_EVT_MODE_UNUSED;
}

void ipipe_host_timer_register(struct clock_event_device *evtdev)
{
	struct ipipe_timer *timer = evtdev->ipipe_timer;

	if (timer == NULL)
		return;

	timer->orig_mode = CLOCK_EVT_MODE_UNUSED;

	if (timer->request == NULL)
		timer->request = ipipe_timer_default_request;

	/*
	 * By default, use the same method as linux timer, on ARM at
	 * least, most set_next_event methods are safe to be called
	 * from Xenomai domain anyway.
	 */
	if (timer->set == NULL) {
		timer->timer_set = evtdev;
		timer->set = (typeof(timer->set))evtdev->set_next_event;
	}

	if (timer->release == NULL)
		timer->release = ipipe_timer_default_release;

	if (timer->name == NULL)
		timer->name = evtdev->name;

	if (timer->rating == 0)
		timer->rating = evtdev->rating;

	timer->freq = (1000000000ULL * evtdev->mult) >> evtdev->shift;

	if (timer->min_delay_ticks == 0)
		timer->min_delay_ticks =
			(evtdev->min_delta_ns * evtdev->mult) >> evtdev->shift;

136 137 138 139
	if (timer->max_delay_ticks == 0)
		timer->max_delay_ticks =
			(evtdev->max_delta_ns * evtdev->mult) >> evtdev->shift;

140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366
	if (timer->cpumask == NULL)
		timer->cpumask = evtdev->cpumask;

	timer->host_timer = evtdev;

	ipipe_timer_register(timer);
}

/*
 * register a timer: maintain them in a list sorted by rating
 */
void ipipe_timer_register(struct ipipe_timer *timer)
{
	struct ipipe_timer *t;
	unsigned long flags;

	if (timer->timer_set == NULL)
		timer->timer_set = timer;

	if (timer->cpumask == NULL)
		timer->cpumask = cpumask_of(smp_processor_id());

	raw_spin_lock_irqsave(&lock, flags);

	list_for_each_entry(t, &timers, link) {
		if (t->rating <= timer->rating) {
			__list_add(&timer->link, t->link.prev, &t->link);
			goto done;
		}
	}
	list_add_tail(&timer->link, &timers);
  done:
	raw_spin_unlock_irqrestore(&lock, flags);
}

static void ipipe_timer_request_sync(void)
{
	struct ipipe_timer *timer = __ipipe_raw_cpu_read(percpu_timer);
	struct clock_event_device *evtdev;
	int steal;

	if (!timer)
		return;

	evtdev = timer->host_timer;
	steal = evtdev != NULL && !clockevent_state_detached(evtdev);
	timer->request(timer, steal);
}

static void config_pcpu_timer(struct ipipe_timer *t, unsigned hrclock_freq)
{
	unsigned long long tmp;
	unsigned hrtimer_freq;

	if (__ipipe_hrtimer_freq != t->freq)
		__ipipe_hrtimer_freq = t->freq;

	hrtimer_freq = t->freq;
	if (__ipipe_hrclock_freq > UINT_MAX)
		hrtimer_freq /= 1000;

	t->c2t_integ = hrtimer_freq / hrclock_freq;
	tmp = (((unsigned long long)
		(hrtimer_freq % hrclock_freq)) << 32)
		+ hrclock_freq - 1;
	do_div(tmp, hrclock_freq);
	t->c2t_frac = tmp;
}

/* Set up a timer as per-cpu timer for ipipe */
static void install_pcpu_timer(unsigned cpu, unsigned hrclock_freq,
			      struct ipipe_timer *t)
{
	per_cpu(ipipe_percpu.hrtimer_irq, cpu) = t->irq;
	per_cpu(percpu_timer, cpu) = t;
	config_pcpu_timer(t, hrclock_freq);
}

static void select_root_only_timer(unsigned cpu, unsigned hrclock_khz,
				   const struct cpumask *mask,
				   struct ipipe_timer *t) {
	unsigned icpu;
	struct clock_event_device *evtdev;

	/*
	 * If no ipipe-supported CPU shares an interrupt with the
	 * timer, we do not need to care about it.
	 */
	for_each_cpu(icpu, mask) {
		if (t->irq == per_cpu(ipipe_percpu.hrtimer_irq, icpu)) {
			evtdev = t->host_timer;
			if (evtdev && clockevent_state_shutdown(evtdev))
				continue;
			goto found;
		}
	}

	return;

found:
	install_pcpu_timer(cpu, hrclock_khz, t);
}

/*
 * Choose per-cpu timers with the highest rating by traversing the
 * rating-sorted list for each CPU.
 */
int ipipe_select_timers(const struct cpumask *mask)
{
	unsigned hrclock_freq;
	unsigned long long tmp;
	struct ipipe_timer *t;
	struct clock_event_device *evtdev;
	unsigned long flags;
	unsigned cpu;
	cpumask_t fixup;

	if (!__ipipe_hrclock_ok()) {
		printk("I-pipe: high-resolution clock not working\n");
		return -ENODEV;
	}

	if (__ipipe_hrclock_freq > UINT_MAX) {
		tmp = __ipipe_hrclock_freq;
		do_div(tmp, 1000);
		hrclock_freq = tmp;
	} else
		hrclock_freq = __ipipe_hrclock_freq;

	raw_spin_lock_irqsave(&lock, flags);

	/* First, choose timers for the CPUs handled by ipipe */
	for_each_cpu(cpu, mask) {
		list_for_each_entry(t, &timers, link) {
			if (!cpumask_test_cpu(cpu, t->cpumask))
				continue;

			evtdev = t->host_timer;
			if (evtdev && clockevent_state_shutdown(evtdev))
				continue;
			goto found;
		}

		printk("I-pipe: could not find timer for cpu #%d\n",
		       cpu);
		goto err_remove_all;
found:
		install_pcpu_timer(cpu, hrclock_freq, t);
	}

	/*
	 * Second, check if we need to fix up any CPUs not supported
	 * by ipipe (but by Linux) whose interrupt may need to be
	 * forwarded because they have the same IRQ as an ipipe-enabled
	 * timer.
	 */
	cpumask_andnot(&fixup, cpu_online_mask, mask);

	for_each_cpu(cpu, &fixup) {
		list_for_each_entry(t, &timers, link) {
			if (!cpumask_test_cpu(cpu, t->cpumask))
				continue;

			select_root_only_timer(cpu, hrclock_freq, mask, t);
		}
	}

	raw_spin_unlock_irqrestore(&lock, flags);

	flags = ipipe_critical_enter(ipipe_timer_request_sync);
	ipipe_timer_request_sync();
	ipipe_critical_exit(flags);

	return 0;

err_remove_all:
	raw_spin_unlock_irqrestore(&lock, flags);

	for_each_cpu(cpu, mask) {
		per_cpu(ipipe_percpu.hrtimer_irq, cpu) = -1;
		per_cpu(percpu_timer, cpu) = NULL;
	}
	__ipipe_hrtimer_freq = 0;

	return -ENODEV;
}

static void ipipe_timer_release_sync(void)
{
	struct ipipe_timer *timer = __ipipe_raw_cpu_read(percpu_timer);

	if (timer)
		timer->release(timer);
}

void ipipe_timers_release(void)
{
	unsigned long flags;
	unsigned cpu;

	flags = ipipe_critical_enter(ipipe_timer_release_sync);
	ipipe_timer_release_sync();
	ipipe_critical_exit(flags);

	for_each_online_cpu(cpu) {
		per_cpu(ipipe_percpu.hrtimer_irq, cpu) = -1;
		per_cpu(percpu_timer, cpu) = NULL;
		__ipipe_hrtimer_freq = 0;
	}
}

static void __ipipe_ack_hrtimer_irq(struct irq_desc *desc)
{
	struct ipipe_timer *timer = __ipipe_raw_cpu_read(percpu_timer);

	if (desc)
		desc->ipipe_ack(desc);
	if (timer->ack)
		timer->ack();
	if (desc)
		desc->ipipe_end(desc);
}

static int do_set_oneshot(struct clock_event_device *cdev)
{
	struct ipipe_timer *timer = __ipipe_raw_cpu_read(percpu_timer);

367
	timer->orig_set_state_oneshot(cdev);
368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390
	timer->mode_handler(CLOCK_EVT_MODE_ONESHOT, cdev);

	return 0;
}

static int do_set_periodic(struct clock_event_device *cdev)
{
	struct ipipe_timer *timer = __ipipe_raw_cpu_read(percpu_timer);

	timer->mode_handler(CLOCK_EVT_MODE_PERIODIC, cdev);

	return 0;
}

static int do_set_shutdown(struct clock_event_device *cdev)
{
	struct ipipe_timer *timer = __ipipe_raw_cpu_read(percpu_timer);

	timer->mode_handler(CLOCK_EVT_MODE_SHUTDOWN, cdev);

	return 0;
}

391 392 393
int clockevents_program_event(struct clock_event_device *dev,
			      ktime_t expires, bool force);

394 395 396 397 398 399 400 401 402 403
struct grab_timer_data {
	void (*tick_handler)(void);
	void (*emumode)(enum clock_event_mode mode,
			struct clock_event_device *cdev);
	int (*emutick)(unsigned long evt,
		       struct clock_event_device *cdev);
	int retval;
};

static void grab_timer(void *arg)
404
{
405
	struct grab_timer_data *data = arg;
406 407 408 409 410 411
	struct clock_event_device *evtdev;
	struct ipipe_timer *timer;
	struct irq_desc *desc;
	unsigned long flags;
	int steal, ret;

412
	flags = hard_local_irq_save();
413

414 415
	timer = this_cpu_read(percpu_timer);
	evtdev = timer->host_timer;
416
	ret = ipipe_request_irq(ipipe_head_domain, timer->irq,
417
				(ipipe_irq_handler_t)data->tick_handler,
418 419
				NULL, __ipipe_ack_hrtimer_irq);
	if (ret < 0 && ret != -EBUSY) {
420 421 422
		hard_local_irq_restore(flags);
		data->retval = ret;
		return;
423 424 425 426 427 428 429 430 431 432 433
	}

	steal = evtdev != NULL && !clockevent_state_detached(evtdev);
	if (steal && evtdev->ipipe_stolen == 0) {
		timer->real_mult = evtdev->mult;
		timer->real_shift = evtdev->shift;
		timer->orig_set_state_periodic = evtdev->set_state_periodic;
		timer->orig_set_state_oneshot = evtdev->set_state_oneshot;
		timer->orig_set_state_oneshot_stopped = evtdev->set_state_oneshot_stopped;
		timer->orig_set_state_shutdown = evtdev->set_state_shutdown;
		timer->orig_set_next_event = evtdev->set_next_event;
434
		timer->mode_handler = data->emumode;
435 436 437
		evtdev->mult = 1;
		evtdev->shift = 0;
		evtdev->max_delta_ns = UINT_MAX;
438 439 440 441 442 443 444 445
		if (timer->orig_set_state_periodic)
			evtdev->set_state_periodic = do_set_periodic;
		if (timer->orig_set_state_oneshot)
			evtdev->set_state_oneshot = do_set_oneshot;
		if (timer->orig_set_state_oneshot_stopped)
			evtdev->set_state_oneshot_stopped = do_set_oneshot;
		if (timer->orig_set_state_shutdown)
			evtdev->set_state_shutdown = do_set_shutdown;
446
		evtdev->set_next_event = data->emutick;
447 448 449
		evtdev->ipipe_stolen = 1;
	}

450
	hard_local_irq_restore(flags);
451

452
	data->retval = get_dev_mode(evtdev);
453 454 455 456 457

	desc = irq_to_desc(timer->irq);
	if (desc && irqd_irq_disabled(&desc->irq_data))
		ipipe_enable_irq(timer->irq);

458
	if (evtdev->ipipe_stolen && clockevent_state_oneshot(evtdev)) {
459 460
		ret = clockevents_program_event(evtdev,
						evtdev->next_event, true);
461 462 463 464 465 466 467 468 469 470 471 472 473 474
		if (ret)
			data->retval = ret;
	}
}

int ipipe_timer_start(void (*tick_handler)(void),
		      void (*emumode)(enum clock_event_mode mode,
				      struct clock_event_device *cdev),
		      int (*emutick)(unsigned long evt,
				     struct clock_event_device *cdev),
		      unsigned int cpu)
{
	struct grab_timer_data data;
	int ret;
475

476 477 478 479 480 481 482
	data.tick_handler = tick_handler;
	data.emutick = emutick;
	data.emumode = emumode;
	data.retval = -EINVAL;
	ret = smp_call_function_single(cpu, grab_timer, &data, true);

	return ret ?: data.retval;
483 484
}

485
static void release_timer(void *arg)
486 487 488 489
{
	struct clock_event_device *evtdev;
	struct ipipe_timer *timer;
	struct irq_desc *desc;
490
	unsigned long flags;
491

492 493 494
	flags = hard_local_irq_save();

	timer = this_cpu_read(percpu_timer);
495 496 497 498 499

	desc = irq_to_desc(timer->irq);
	if (desc && irqd_irq_disabled(&desc->irq_data))
		ipipe_disable_irq(timer->irq);

500
	ipipe_free_irq(ipipe_head_domain, timer->irq);
501

502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518
	evtdev = timer->host_timer;
	if (evtdev && evtdev->ipipe_stolen) {
		evtdev->mult = timer->real_mult;
		evtdev->shift = timer->real_shift;
		evtdev->set_state_periodic = timer->orig_set_state_periodic;
		evtdev->set_state_oneshot = timer->orig_set_state_oneshot;
		evtdev->set_state_oneshot_stopped = timer->orig_set_state_oneshot_stopped;
		evtdev->set_state_shutdown = timer->orig_set_state_shutdown;
		evtdev->set_next_event = timer->orig_set_next_event;
		evtdev->ipipe_stolen = 0;
		hard_local_irq_restore(flags);
		if (clockevent_state_oneshot(evtdev))
			clockevents_program_event(evtdev,
						  evtdev->next_event, true);
	} else
		hard_local_irq_restore(flags);
}
519

520 521 522
void ipipe_timer_stop(unsigned int cpu)
{
	smp_call_function_single(cpu, release_timer, NULL, true);
523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548
}

void ipipe_timer_set(unsigned long cdelay)
{
	unsigned long tdelay;
	struct ipipe_timer *t;

	t = __ipipe_raw_cpu_read(percpu_timer);

	/*
	 * Even though some architectures may use a 64 bits delay
	 * here, we voluntarily limit to 32 bits, 4 billions ticks
	 * should be enough for now. Would a timer needs more, an
	 * extra call to the tick handler would simply occur after 4
	 * billions ticks.
	 */
	if (cdelay > UINT_MAX)
		cdelay = UINT_MAX;

	tdelay = cdelay;
	if (t->c2t_integ != 1)
		tdelay *= t->c2t_integ;
	if (t->c2t_frac)
		tdelay += ((unsigned long long)cdelay * t->c2t_frac) >> 32;
	if (tdelay < t->min_delay_ticks)
		tdelay = t->min_delay_ticks;
549 550
	if (tdelay > t->max_delay_ticks)
		tdelay = t->max_delay_ticks;
551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618

	if (t->set(tdelay, t->timer_set) < 0)
		ipipe_raise_irq(t->irq);
}
EXPORT_SYMBOL_GPL(ipipe_timer_set);

const char *ipipe_timer_name(void)
{
	return per_cpu(percpu_timer, 0)->name;
}
EXPORT_SYMBOL_GPL(ipipe_timer_name);

unsigned ipipe_timer_ns2ticks(struct ipipe_timer *timer, unsigned ns)
{
	unsigned long long tmp;
	BUG_ON(!timer->freq);
	tmp = (unsigned long long)ns * timer->freq;
	do_div(tmp, 1000000000);
	return tmp;
}

#ifdef CONFIG_IPIPE_HAVE_HOSTRT
/*
 * NOTE: The architecture specific code must only call this function
 * when a clocksource suitable for CLOCK_HOST_REALTIME is enabled.
 * The event receiver is responsible for providing proper locking.
 */
void ipipe_update_hostrt(struct timekeeper *tk)
{
	struct tk_read_base *tkr = &tk->tkr_mono;
	struct clocksource *clock = tkr->clock;
	struct ipipe_hostrt_data data;
	struct timespec xt;

	xt.tv_sec = tk->xtime_sec;
	xt.tv_nsec = (long)(tkr->xtime_nsec >> tkr->shift);
	ipipe_root_only();
	data.live = 1;
	data.cycle_last = tkr->cycle_last;
	data.mask = clock->mask;
	data.mult = tkr->mult;
	data.shift = tkr->shift;
	data.wall_time_sec = xt.tv_sec;
	data.wall_time_nsec = xt.tv_nsec;
	data.wall_to_monotonic.tv_sec = tk->wall_to_monotonic.tv_sec;
	data.wall_to_monotonic.tv_nsec = tk->wall_to_monotonic.tv_nsec;
	__ipipe_notify_kevent(IPIPE_KEVT_HOSTRT, &data);
}

#endif /* CONFIG_IPIPE_HAVE_HOSTRT */

int clockevents_program_event(struct clock_event_device *dev, ktime_t expires,
			      bool force);

void __ipipe_timer_refresh_freq(unsigned int hrclock_freq)
{
	struct ipipe_timer *t = __ipipe_raw_cpu_read(percpu_timer);
	unsigned long flags;

	if (t && t->refresh_freq) {
		t->freq = t->refresh_freq();
		flags = hard_local_irq_save();
		config_pcpu_timer(t, hrclock_freq);
		hard_local_irq_restore(flags);
		clockevents_program_event(t->host_timer,
					  t->host_timer->next_event, false);
	}
}