1 // SPDX-License-Identifier: GPL-2.0
3  * This file contains functions which manage clock event devices.
5  * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
6  * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
7  * Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner
17 #include "tick-internal.h"
19 /* The registered clock event devices */
35 	u64 clc = (u64) latch << evt->shift;  in cev_delta2ns()
38 	if (WARN_ON(!evt->mult))  in cev_delta2ns()
39 		evt->mult = 1;  in cev_delta2ns()
40 	rnd = (u64) evt->mult - 1;  in cev_delta2ns()
46 	if ((clc >> evt->shift) != (u64)latch)  in cev_delta2ns()
52 	 * For mult <= (1 << shift) we can safely add mult - 1 to  in cev_delta2ns()
56 	 * For mult > (1 << shift), i.e. device frequency is > 1GHz we  in cev_delta2ns()
57 	 * need to be careful. Adding mult - 1 will result in a value  in cev_delta2ns()
59 	 * than latch by up to (mult - 1) >> shift. For the min_delta  in cev_delta2ns()
68 	if ((~0ULL - clc > rnd) &&  in cev_delta2ns()
69 	    (!ismax || evt->mult <= (1ULL << evt->shift)))  in cev_delta2ns()
72 	do_div(clc, evt->mult);  in cev_delta2ns()
79  * clockevents_delta2ns - Convert a latch value (device ticks) to nanoseconds
81  * @evt:	pointer to clock event device descriptor
94 	if (dev->features & CLOCK_EVT_FEAT_DUMMY)  in __clockevents_switch_state()
97 	/* Transition with new state-specific callbacks */  in __clockevents_switch_state()
103 		if (dev->set_state_shutdown)  in __clockevents_switch_state()
104 			return dev->set_state_shutdown(dev);  in __clockevents_switch_state()
109 		if (!(dev->features & CLOCK_EVT_FEAT_PERIODIC))  in __clockevents_switch_state()
110 			return -ENOSYS;  in __clockevents_switch_state()
111 		if (dev->set_state_periodic)  in __clockevents_switch_state()
112 			return dev->set_state_periodic(dev);  in __clockevents_switch_state()
117 		if (!(dev->features & CLOCK_EVT_FEAT_ONESHOT))  in __clockevents_switch_state()
118 			return -ENOSYS;  in __clockevents_switch_state()
119 		if (dev->set_state_oneshot)  in __clockevents_switch_state()
120 			return dev->set_state_oneshot(dev);  in __clockevents_switch_state()
128 			return -EINVAL;  in __clockevents_switch_state()
130 		if (dev->set_state_oneshot_stopped)  in __clockevents_switch_state()
131 			return dev->set_state_oneshot_stopped(dev);  in __clockevents_switch_state()
133 			return -ENOSYS;  in __clockevents_switch_state()
136 		return -ENOSYS;  in __clockevents_switch_state()
141  * clockevents_switch_state - set the operating state of a clock event device
161 			if (WARN_ON(!dev->mult))  in clockevents_switch_state()
162 				dev->mult = 1;  in clockevents_switch_state()
168  * clockevents_shutdown - shutdown the device and clear next_event
174 	dev->next_event = KTIME_MAX;  in clockevents_shutdown()
178  * clockevents_tick_resume -	Resume the tick device before using it again
185 	if (dev->tick_resume)  in clockevents_tick_resume()
186 		ret = dev->tick_resume(dev);  in clockevents_tick_resume()
197  * clockevents_increase_min_delta - raise minimum delta of a clock event device
200  * Returns 0 on success, -ETIME when the minimum delta reached the limit.
205 	if (dev->min_delta_ns >= MIN_DELTA_LIMIT) {  in clockevents_increase_min_delta()
208 		dev->next_event = KTIME_MAX;  in clockevents_increase_min_delta()
209 		return -ETIME;  in clockevents_increase_min_delta()
212 	if (dev->min_delta_ns < 5000)  in clockevents_increase_min_delta()
213 		dev->min_delta_ns = 5000;  in clockevents_increase_min_delta()
215 		dev->min_delta_ns += dev->min_delta_ns >> 1;  in clockevents_increase_min_delta()
217 	if (dev->min_delta_ns > MIN_DELTA_LIMIT)  in clockevents_increase_min_delta()
218 		dev->min_delta_ns = MIN_DELTA_LIMIT;  in clockevents_increase_min_delta()
222 			dev->name ? dev->name : "?",  in clockevents_increase_min_delta()
223 			(unsigned long long) dev->min_delta_ns);  in clockevents_increase_min_delta()
228  * clockevents_program_min_delta - Set clock event device to the minimum delay.
231  * Returns 0 on success, -ETIME when the retry loop failed.
240 		delta = dev->min_delta_ns;  in clockevents_program_min_delta()
241 		dev->next_event = ktime_add_ns(ktime_get(), delta);  in clockevents_program_min_delta()
246 		dev->retries++;  in clockevents_program_min_delta()
247 		clc = ((unsigned long long) delta * dev->mult) >> dev->shift;  in clockevents_program_min_delta()
248 		if (dev->set_next_event((unsigned long) clc, dev) == 0)  in clockevents_program_min_delta()
258 				return -ETIME;  in clockevents_program_min_delta()
267  * clockevents_program_min_delta - Set clock event device to the minimum delay.
270  * Returns 0 on success, -ETIME when the retry loop failed.
279 		delta += dev->min_delta_ns;  in clockevents_program_min_delta()
280 		dev->next_event = ktime_add_ns(ktime_get(), delta);  in clockevents_program_min_delta()
285 		dev->retries++;  in clockevents_program_min_delta()
286 		clc = ((unsigned long long) delta * dev->mult) >> dev->shift;  in clockevents_program_min_delta()
287 		if (dev->set_next_event((unsigned long) clc, dev) == 0)  in clockevents_program_min_delta()
290 	return -ETIME;  in clockevents_program_min_delta()
296  * clockevents_program_event - Reprogram the clock event device.
298  * @expires:	absolute expiry time (monotonic clock)
301  * Returns 0 on success, -ETIME when the event is in the past.
311 		return -ETIME;  in clockevents_program_event()
313 	dev->next_event = expires;  in clockevents_program_event()
323 	if (dev->features & CLOCK_EVT_FEAT_KTIME)  in clockevents_program_event()
324 		return dev->set_next_ktime(expires, dev);  in clockevents_program_event()
328 		return force ? clockevents_program_min_delta(dev) : -ETIME;  in clockevents_program_event()
330 	delta = min(delta, (int64_t) dev->max_delta_ns);  in clockevents_program_event()
331 	delta = max(delta, (int64_t) dev->min_delta_ns);  in clockevents_program_event()
333 	clc = ((unsigned long long) delta * dev->mult) >> dev->shift;  in clockevents_program_event()
334 	rc = dev->set_next_event((unsigned long) clc, dev);  in clockevents_program_event()
350 		list_del(&dev->list);  in clockevents_notify_released()
351 		list_add(&dev->list, &clockevent_devices);  in clockevents_notify_released()
357  * Try to install a replacement clock event device
370 		if (!try_module_get(dev->owner))  in clockevents_replace()
374 			module_put(newdev->owner);  in clockevents_replace()
379 		list_del_init(&ced->list);  in clockevents_replace()
381 	return newdev ? 0 : -EBUSY;  in clockevents_replace()
391 		list_del_init(&ced->list);  in __clockevents_try_unbind()
395 	return ced == per_cpu(tick_cpu_device, cpu).evtdev ? -EAGAIN : -EBUSY;  in __clockevents_try_unbind()
407 	res = __clockevents_try_unbind(cu->ce, smp_processor_id());  in __clockevents_unbind()
408 	if (res == -EAGAIN)  in __clockevents_unbind()
409 		res = clockevents_replace(cu->ce);  in __clockevents_unbind()
410 	cu->res = res;  in __clockevents_unbind()
420 	struct ce_unbind cu = { .ce = ced, .res = -ENODEV };  in clockevents_unbind()
441  * clockevents_register_device - register a clock event device
451 	if (!dev->cpumask) {  in clockevents_register_device()
453 		dev->cpumask = cpumask_of(smp_processor_id());  in clockevents_register_device()
456 	if (dev->cpumask == cpu_all_mask) {  in clockevents_register_device()
458 		     dev->name);  in clockevents_register_device()
459 		dev->cpumask = cpu_possible_mask;  in clockevents_register_device()
464 	list_add(&dev->list, &clockevent_devices);  in clockevents_register_device()
476 	if (!(dev->features & CLOCK_EVT_FEAT_ONESHOT))  in clockevents_config()
484 	sec = dev->max_delta_ticks;  in clockevents_config()
488 	else if (sec > 600 && dev->max_delta_ticks > UINT_MAX)  in clockevents_config()
492 	dev->min_delta_ns = cev_delta2ns(dev->min_delta_ticks, dev, false);  in clockevents_config()
493 	dev->max_delta_ns = cev_delta2ns(dev->max_delta_ticks, dev, true);  in clockevents_config()
497  * clockevents_config_and_register - Configure and register a clock event device
499  * @freq:	The clock frequency
500  * @min_delta:	The minimum clock ticks to program in oneshot mode
501  * @max_delta:	The maximum clock ticks to program in oneshot mode
509 	dev->min_delta_ticks = min_delta;  in clockevents_config_and_register()
510 	dev->max_delta_ticks = max_delta;  in clockevents_config_and_register()
521 		return clockevents_program_event(dev, dev->next_event, false);  in __clockevents_update_freq()
530  * clockevents_update_freq - Update frequency and reprogram a clock event device.
534  * Reconfigure and reprogram a clock event device in oneshot
539  * Returns 0 on success, -ETIME when the event is in the past.
548 	if (ret == -ENODEV)  in clockevents_update_freq()
562  * clockevents_exchange_device - release and request clock devices
573 	 * Caller releases a clock event device. We queue it into the  in clockevents_exchange_device()
577 		module_put(old->owner);  in clockevents_exchange_device()
579 		list_del(&old->list);  in clockevents_exchange_device()
580 		list_add(&old->list, &clockevents_released);  in clockevents_exchange_device()
590  * clockevents_suspend - suspend clock devices
597 		if (dev->suspend && !clockevent_state_detached(dev))  in clockevents_suspend()
598 			dev->suspend(dev);  in clockevents_suspend()
602  * clockevents_resume - resume clock devices
609 		if (dev->resume && !clockevent_state_detached(dev))  in clockevents_resume()
610 			dev->resume(dev);  in clockevents_resume()
617  * tick_offline_cpu - Take CPU out of the broadcast mechanism
631  * tick_cleanup_dead_cpu - Cleanup the tick and clockevents of a dead cpu
642 	 * Unregister the clock event devices which were  in tick_cleanup_dead_cpu()
646 		list_del(&dev->list);  in tick_cleanup_dead_cpu()
651 		if (cpumask_test_cpu(cpu, dev->cpumask) &&  in tick_cleanup_dead_cpu()
652 		    cpumask_weight(dev->cpumask) == 1 &&  in tick_cleanup_dead_cpu()
655 			list_del(&dev->list);  in tick_cleanup_dead_cpu()
680 	if (td && td->evtdev)  in sysfs_show_current_tick_dev()
681 		count = snprintf(buf, PAGE_SIZE, "%s\n", td->evtdev->name);  in sysfs_show_current_tick_dev()
699 	ret = -ENODEV;  in sysfs_unbind_tick_dev()
703 		if (!strcmp(ce->name, name)) {  in sysfs_unbind_tick_dev()
704 			ret = __clockevents_try_unbind(ce, dev->id);  in sysfs_unbind_tick_dev()
712 	if (ret == -EAGAIN)  in sysfs_unbind_tick_dev()
713 		ret = clockevents_unbind(ce, dev->id);  in sysfs_unbind_tick_dev()
729 		&per_cpu(tick_cpu_device, dev->id);  in tick_get_tick_dev()
743 	return &per_cpu(tick_cpu_device, dev->id);  in tick_get_tick_dev()
756 		dev->id = cpu;  in tick_init_sysfs()
757 		dev->bus = &clockevents_subsys;  in tick_init_sysfs()