blob: da6c9ecad4e47fc0758ed70d184eec8847400b20 [file] [log] [blame]
Thomas Gleixner906568c2007-02-16 01:28:01 -08001/*
2 * linux/kernel/time/tick-common.c
3 *
4 * This file contains the base functions to manage periodic tick
5 * related events.
6 *
7 * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
8 * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
9 * Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner
10 *
11 * This code is licenced under the GPL version 2. For details see
12 * kernel-base/COPYING.
13 */
14#include <linux/cpu.h>
15#include <linux/err.h>
16#include <linux/hrtimer.h>
Russell Kingd7b90682008-04-17 07:46:24 +020017#include <linux/interrupt.h>
Thomas Gleixner906568c2007-02-16 01:28:01 -080018#include <linux/percpu.h>
19#include <linux/profile.h>
20#include <linux/sched.h>
Thomas Gleixner906568c2007-02-16 01:28:01 -080021
Russell Kingd7b90682008-04-17 07:46:24 +020022#include <asm/irq_regs.h>
23
Thomas Gleixnerf8381cb2007-02-16 01:28:02 -080024#include "tick-internal.h"
25
Thomas Gleixner906568c2007-02-16 01:28:01 -080026/*
27 * Tick devices
28 */
Thomas Gleixnerf8381cb2007-02-16 01:28:02 -080029DEFINE_PER_CPU(struct tick_device, tick_cpu_device);
Thomas Gleixner906568c2007-02-16 01:28:01 -080030/*
31 * Tick next event: keeps track of the tick time
32 */
Thomas Gleixnerf8381cb2007-02-16 01:28:02 -080033ktime_t tick_next_period;
34ktime_t tick_period;
Thomas Gleixner64414022008-09-22 18:46:37 +020035int tick_do_timer_cpu __read_mostly = TICK_DO_TIMER_BOOT;
Thomas Gleixnerb5f91da2009-12-08 12:40:31 +010036static DEFINE_RAW_SPINLOCK(tick_device_lock);
Thomas Gleixner906568c2007-02-16 01:28:01 -080037
Ingo Molnar289f4802007-02-16 01:28:15 -080038/*
39 * Debugging: see timer_list.c
40 */
41struct tick_device *tick_get_device(int cpu)
42{
43 return &per_cpu(tick_cpu_device, cpu);
44}
45
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -080046/**
47 * tick_is_oneshot_available - check for a oneshot capable event device
48 */
49int tick_is_oneshot_available(void)
50{
Christoph Lameter909ea962010-12-08 16:22:55 +010051 struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev);
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -080052
Thomas Gleixner3a142a02011-02-25 22:34:23 +010053 if (!dev || !(dev->features & CLOCK_EVT_FEAT_ONESHOT))
54 return 0;
55 if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
56 return 1;
57 return tick_broadcast_oneshot_available();
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -080058}
59
Thomas Gleixner906568c2007-02-16 01:28:01 -080060/*
61 * Periodic tick
62 */
63static void tick_periodic(int cpu)
64{
65 if (tick_do_timer_cpu == cpu) {
66 write_seqlock(&xtime_lock);
67
68 /* Keep track of the next tick event */
69 tick_next_period = ktime_add(tick_next_period, tick_period);
70
71 do_timer(1);
72 write_sequnlock(&xtime_lock);
73 }
74
75 update_process_times(user_mode(get_irq_regs()));
76 profile_tick(CPU_PROFILING);
77}
78
79/*
80 * Event handler for periodic ticks
81 */
82void tick_handle_periodic(struct clock_event_device *dev)
83{
84 int cpu = smp_processor_id();
David S. Miller3494c162007-02-24 22:11:42 -080085 ktime_t next;
Thomas Gleixner906568c2007-02-16 01:28:01 -080086
87 tick_periodic(cpu);
88
89 if (dev->mode != CLOCK_EVT_MODE_ONESHOT)
90 return;
91 /*
92 * Setup the next period for devices, which do not have
93 * periodic mode:
94 */
David S. Miller3494c162007-02-24 22:11:42 -080095 next = ktime_add(dev->next_event, tick_period);
Thomas Gleixner906568c2007-02-16 01:28:01 -080096 for (;;) {
Martin Schwidefskyd1748302011-08-23 15:29:42 +020097 if (!clockevents_program_event(dev, next, false))
Thomas Gleixner906568c2007-02-16 01:28:01 -080098 return;
john stultz74a03b62009-05-01 13:10:25 -070099 /*
100 * Have to be careful here. If we're in oneshot mode,
101 * before we call tick_periodic() in a loop, we need
102 * to be sure we're using a real hardware clocksource.
103 * Otherwise we could get trapped in an infinite
104 * loop, as the tick_periodic() increments jiffies,
105 * when then will increment time, posibly causing
106 * the loop to trigger again and again.
107 */
108 if (timekeeping_valid_for_hres())
109 tick_periodic(cpu);
David S. Miller3494c162007-02-24 22:11:42 -0800110 next = ktime_add(next, tick_period);
Thomas Gleixner906568c2007-02-16 01:28:01 -0800111 }
112}
113
114/*
115 * Setup the device for a periodic tick
116 */
Thomas Gleixnerf8381cb2007-02-16 01:28:02 -0800117void tick_setup_periodic(struct clock_event_device *dev, int broadcast)
Thomas Gleixner906568c2007-02-16 01:28:01 -0800118{
Thomas Gleixnerf8381cb2007-02-16 01:28:02 -0800119 tick_set_periodic_handler(dev, broadcast);
120
121 /* Broadcast setup ? */
122 if (!tick_device_is_functional(dev))
123 return;
Thomas Gleixner906568c2007-02-16 01:28:01 -0800124
Thomas Gleixner27ce4cb2008-09-22 19:04:02 +0200125 if ((dev->features & CLOCK_EVT_FEAT_PERIODIC) &&
126 !tick_broadcast_oneshot_active()) {
Thomas Gleixner906568c2007-02-16 01:28:01 -0800127 clockevents_set_mode(dev, CLOCK_EVT_MODE_PERIODIC);
128 } else {
129 unsigned long seq;
130 ktime_t next;
131
132 do {
133 seq = read_seqbegin(&xtime_lock);
134 next = tick_next_period;
135 } while (read_seqretry(&xtime_lock, seq));
136
137 clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
138
139 for (;;) {
Martin Schwidefskyd1748302011-08-23 15:29:42 +0200140 if (!clockevents_program_event(dev, next, false))
Thomas Gleixner906568c2007-02-16 01:28:01 -0800141 return;
142 next = ktime_add(next, tick_period);
143 }
144 }
145}
146
147/*
148 * Setup the tick device
149 */
150static void tick_setup_device(struct tick_device *td,
151 struct clock_event_device *newdev, int cpu,
Rusty Russell0de26522008-12-13 21:20:26 +1030152 const struct cpumask *cpumask)
Thomas Gleixner906568c2007-02-16 01:28:01 -0800153{
154 ktime_t next_event;
155 void (*handler)(struct clock_event_device *) = NULL;
156
157 /*
158 * First device setup ?
159 */
160 if (!td->evtdev) {
161 /*
162 * If no cpu took the do_timer update, assign it to
163 * this cpu:
164 */
Thomas Gleixner64414022008-09-22 18:46:37 +0200165 if (tick_do_timer_cpu == TICK_DO_TIMER_BOOT) {
Thomas Gleixner906568c2007-02-16 01:28:01 -0800166 tick_do_timer_cpu = cpu;
167 tick_next_period = ktime_get();
168 tick_period = ktime_set(0, NSEC_PER_SEC / HZ);
169 }
170
171 /*
172 * Startup in periodic mode first.
173 */
174 td->mode = TICKDEV_MODE_PERIODIC;
175 } else {
176 handler = td->evtdev->event_handler;
177 next_event = td->evtdev->next_event;
Venkatesh Pallipadi7c1e7682008-09-03 21:36:50 +0000178 td->evtdev->event_handler = clockevents_handle_noop;
Thomas Gleixner906568c2007-02-16 01:28:01 -0800179 }
180
181 td->evtdev = newdev;
182
183 /*
184 * When the device is not per cpu, pin the interrupt to the
185 * current cpu:
186 */
Rusty Russell320ab2b2008-12-13 21:20:26 +1030187 if (!cpumask_equal(newdev->cpumask, cpumask))
Rusty Russell0de26522008-12-13 21:20:26 +1030188 irq_set_affinity(newdev->irq, cpumask);
Thomas Gleixner906568c2007-02-16 01:28:01 -0800189
Thomas Gleixnerf8381cb2007-02-16 01:28:02 -0800190 /*
191 * When global broadcasting is active, check if the current
192 * device is registered as a placeholder for broadcast mode.
193 * This allows us to handle this x86 misfeature in a generic
194 * way.
195 */
196 if (tick_device_uses_broadcast(newdev, cpu))
197 return;
198
Thomas Gleixner906568c2007-02-16 01:28:01 -0800199 if (td->mode == TICKDEV_MODE_PERIODIC)
200 tick_setup_periodic(newdev, 0);
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -0800201 else
202 tick_setup_oneshot(newdev, handler, next_event);
Thomas Gleixner906568c2007-02-16 01:28:01 -0800203}
204
205/*
206 * Check, if the new registered device should be used.
207 */
208static int tick_check_new_device(struct clock_event_device *newdev)
209{
210 struct clock_event_device *curdev;
211 struct tick_device *td;
212 int cpu, ret = NOTIFY_OK;
213 unsigned long flags;
Thomas Gleixner906568c2007-02-16 01:28:01 -0800214
Thomas Gleixnerb5f91da2009-12-08 12:40:31 +0100215 raw_spin_lock_irqsave(&tick_device_lock, flags);
Thomas Gleixner906568c2007-02-16 01:28:01 -0800216
217 cpu = smp_processor_id();
Rusty Russell320ab2b2008-12-13 21:20:26 +1030218 if (!cpumask_test_cpu(cpu, newdev->cpumask))
Venki Pallipadi4a932322007-10-12 23:04:23 +0200219 goto out_bc;
Thomas Gleixner906568c2007-02-16 01:28:01 -0800220
221 td = &per_cpu(tick_cpu_device, cpu);
222 curdev = td->evtdev;
Thomas Gleixner906568c2007-02-16 01:28:01 -0800223
224 /* cpu local device ? */
Rusty Russell320ab2b2008-12-13 21:20:26 +1030225 if (!cpumask_equal(newdev->cpumask, cpumask_of(cpu))) {
Thomas Gleixner906568c2007-02-16 01:28:01 -0800226
227 /*
228 * If the cpu affinity of the device interrupt can not
229 * be set, ignore it.
230 */
231 if (!irq_can_set_affinity(newdev->irq))
232 goto out_bc;
233
234 /*
235 * If we have a cpu local device already, do not replace it
236 * by a non cpu local device
237 */
Rusty Russell320ab2b2008-12-13 21:20:26 +1030238 if (curdev && cpumask_equal(curdev->cpumask, cpumask_of(cpu)))
Thomas Gleixner906568c2007-02-16 01:28:01 -0800239 goto out_bc;
240 }
241
242 /*
243 * If we have an active device, then check the rating and the oneshot
244 * feature.
245 */
246 if (curdev) {
247 /*
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -0800248 * Prefer one shot capable devices !
249 */
250 if ((curdev->features & CLOCK_EVT_FEAT_ONESHOT) &&
251 !(newdev->features & CLOCK_EVT_FEAT_ONESHOT))
252 goto out_bc;
253 /*
Thomas Gleixner906568c2007-02-16 01:28:01 -0800254 * Check the rating
255 */
256 if (curdev->rating >= newdev->rating)
Thomas Gleixnerf8381cb2007-02-16 01:28:02 -0800257 goto out_bc;
Thomas Gleixner906568c2007-02-16 01:28:01 -0800258 }
259
260 /*
261 * Replace the eventually existing device by the new
Thomas Gleixnerf8381cb2007-02-16 01:28:02 -0800262 * device. If the current device is the broadcast device, do
263 * not give it back to the clockevents layer !
Thomas Gleixner906568c2007-02-16 01:28:01 -0800264 */
Thomas Gleixnerf8381cb2007-02-16 01:28:02 -0800265 if (tick_is_broadcast_device(curdev)) {
Thomas Gleixner2344abb2008-09-16 11:32:50 -0700266 clockevents_shutdown(curdev);
Thomas Gleixnerf8381cb2007-02-16 01:28:02 -0800267 curdev = NULL;
268 }
Thomas Gleixner906568c2007-02-16 01:28:01 -0800269 clockevents_exchange_device(curdev, newdev);
Rusty Russell6b954822009-01-01 10:12:25 +1030270 tick_setup_device(td, newdev, cpu, cpumask_of(cpu));
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -0800271 if (newdev->features & CLOCK_EVT_FEAT_ONESHOT)
272 tick_oneshot_notify();
Thomas Gleixner906568c2007-02-16 01:28:01 -0800273
Thomas Gleixnerb5f91da2009-12-08 12:40:31 +0100274 raw_spin_unlock_irqrestore(&tick_device_lock, flags);
Thomas Gleixnerf8381cb2007-02-16 01:28:02 -0800275 return NOTIFY_STOP;
276
277out_bc:
278 /*
279 * Can the new device be used as a broadcast device ?
280 */
281 if (tick_check_broadcast_device(newdev))
282 ret = NOTIFY_STOP;
Venki Pallipadi4a932322007-10-12 23:04:23 +0200283
Thomas Gleixnerb5f91da2009-12-08 12:40:31 +0100284 raw_spin_unlock_irqrestore(&tick_device_lock, flags);
Thomas Gleixnerf8381cb2007-02-16 01:28:02 -0800285
Thomas Gleixner906568c2007-02-16 01:28:01 -0800286 return ret;
287}
288
289/*
Sebastien Dugue94df7de2008-12-01 14:09:07 +0100290 * Transfer the do_timer job away from a dying cpu.
291 *
292 * Called with interrupts disabled.
293 */
294static void tick_handover_do_timer(int *cpup)
295{
296 if (*cpup == tick_do_timer_cpu) {
297 int cpu = cpumask_first(cpu_online_mask);
298
299 tick_do_timer_cpu = (cpu < nr_cpu_ids) ? cpu :
300 TICK_DO_TIMER_NONE;
301 }
302}
303
304/*
Thomas Gleixner906568c2007-02-16 01:28:01 -0800305 * Shutdown an event device on a given cpu:
306 *
307 * This is called on a life CPU, when a CPU is dead. So we cannot
308 * access the hardware device itself.
309 * We just set the mode and remove it from the lists.
310 */
311static void tick_shutdown(unsigned int *cpup)
312{
313 struct tick_device *td = &per_cpu(tick_cpu_device, *cpup);
314 struct clock_event_device *dev = td->evtdev;
315 unsigned long flags;
316
Thomas Gleixnerb5f91da2009-12-08 12:40:31 +0100317 raw_spin_lock_irqsave(&tick_device_lock, flags);
Thomas Gleixner906568c2007-02-16 01:28:01 -0800318 td->mode = TICKDEV_MODE_PERIODIC;
319 if (dev) {
320 /*
321 * Prevent that the clock events layer tries to call
322 * the set mode function!
323 */
324 dev->mode = CLOCK_EVT_MODE_UNUSED;
325 clockevents_exchange_device(dev, NULL);
326 td->evtdev = NULL;
327 }
Thomas Gleixnerb5f91da2009-12-08 12:40:31 +0100328 raw_spin_unlock_irqrestore(&tick_device_lock, flags);
Thomas Gleixner906568c2007-02-16 01:28:01 -0800329}
330
Thomas Gleixnercd05a1f2007-03-17 00:25:52 +0100331static void tick_suspend(void)
Thomas Gleixner6321dd62007-03-06 08:25:42 +0100332{
333 struct tick_device *td = &__get_cpu_var(tick_cpu_device);
334 unsigned long flags;
335
Thomas Gleixnerb5f91da2009-12-08 12:40:31 +0100336 raw_spin_lock_irqsave(&tick_device_lock, flags);
Thomas Gleixner2344abb2008-09-16 11:32:50 -0700337 clockevents_shutdown(td->evtdev);
Thomas Gleixnerb5f91da2009-12-08 12:40:31 +0100338 raw_spin_unlock_irqrestore(&tick_device_lock, flags);
Thomas Gleixner6321dd62007-03-06 08:25:42 +0100339}
340
Thomas Gleixnercd05a1f2007-03-17 00:25:52 +0100341static void tick_resume(void)
Thomas Gleixner6321dd62007-03-06 08:25:42 +0100342{
343 struct tick_device *td = &__get_cpu_var(tick_cpu_device);
344 unsigned long flags;
Thomas Gleixner18de5bc2007-07-21 04:37:34 -0700345 int broadcast = tick_resume_broadcast();
Thomas Gleixner6321dd62007-03-06 08:25:42 +0100346
Thomas Gleixnerb5f91da2009-12-08 12:40:31 +0100347 raw_spin_lock_irqsave(&tick_device_lock, flags);
Thomas Gleixner18de5bc2007-07-21 04:37:34 -0700348 clockevents_set_mode(td->evtdev, CLOCK_EVT_MODE_RESUME);
349
350 if (!broadcast) {
351 if (td->mode == TICKDEV_MODE_PERIODIC)
352 tick_setup_periodic(td->evtdev, 0);
353 else
354 tick_resume_oneshot();
355 }
Thomas Gleixnerb5f91da2009-12-08 12:40:31 +0100356 raw_spin_unlock_irqrestore(&tick_device_lock, flags);
Thomas Gleixner6321dd62007-03-06 08:25:42 +0100357}
358
Thomas Gleixner906568c2007-02-16 01:28:01 -0800359/*
360 * Notification about clock event devices
361 */
362static int tick_notify(struct notifier_block *nb, unsigned long reason,
363 void *dev)
364{
365 switch (reason) {
366
367 case CLOCK_EVT_NOTIFY_ADD:
368 return tick_check_new_device(dev);
369
Thomas Gleixnerf8381cb2007-02-16 01:28:02 -0800370 case CLOCK_EVT_NOTIFY_BROADCAST_ON:
371 case CLOCK_EVT_NOTIFY_BROADCAST_OFF:
Thomas Gleixner1595f452007-10-14 22:57:45 +0200372 case CLOCK_EVT_NOTIFY_BROADCAST_FORCE:
Thomas Gleixnerf8381cb2007-02-16 01:28:02 -0800373 tick_broadcast_on_off(reason, dev);
374 break;
375
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -0800376 case CLOCK_EVT_NOTIFY_BROADCAST_ENTER:
377 case CLOCK_EVT_NOTIFY_BROADCAST_EXIT:
378 tick_broadcast_oneshot_control(reason);
379 break;
380
Sebastien Dugue94df7de2008-12-01 14:09:07 +0100381 case CLOCK_EVT_NOTIFY_CPU_DYING:
382 tick_handover_do_timer(dev);
383 break;
384
Thomas Gleixner906568c2007-02-16 01:28:01 -0800385 case CLOCK_EVT_NOTIFY_CPU_DEAD:
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -0800386 tick_shutdown_broadcast_oneshot(dev);
Thomas Gleixnerf8381cb2007-02-16 01:28:02 -0800387 tick_shutdown_broadcast(dev);
Thomas Gleixner906568c2007-02-16 01:28:01 -0800388 tick_shutdown(dev);
389 break;
390
Thomas Gleixner6321dd62007-03-06 08:25:42 +0100391 case CLOCK_EVT_NOTIFY_SUSPEND:
Thomas Gleixnercd05a1f2007-03-17 00:25:52 +0100392 tick_suspend();
Thomas Gleixner6321dd62007-03-06 08:25:42 +0100393 tick_suspend_broadcast();
394 break;
395
396 case CLOCK_EVT_NOTIFY_RESUME:
Thomas Gleixner18de5bc2007-07-21 04:37:34 -0700397 tick_resume();
Thomas Gleixner6321dd62007-03-06 08:25:42 +0100398 break;
399
Thomas Gleixner906568c2007-02-16 01:28:01 -0800400 default:
401 break;
402 }
403
404 return NOTIFY_OK;
405}
406
407static struct notifier_block tick_notifier = {
408 .notifier_call = tick_notify,
409};
410
411/**
412 * tick_init - initialize the tick control
413 *
414 * Register the notifier with the clockevents framework
415 */
416void __init tick_init(void)
417{
418 clockevents_register_notifier(&tick_notifier);
419}