1 /*
2 * linux/kernel/time/tick-broadcast.c
3 *
4 * This file contains functions which emulate a local clock-event
5 * device via a broadcast event source.
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>
17 #include <linux/interrupt.h>
18 #include <linux/percpu.h>
19 #include <linux/profile.h>
20 #include <linux/sched.h>
21 #include <linux/tick.h>
22
23 #include "tick-internal.h"
24
25 /*
26 * Broadcast support for broken x86 hardware, where the local apic
27 * timer stops in C3 state.
28 */
29
30 static struct tick_device tick_broadcast_device;
31 /* FIXME: Use cpumask_var_t. */
32 static DECLARE_BITMAP(tick_broadcast_mask, NR_CPUS);
33 static DECLARE_BITMAP(tmpmask, NR_CPUS);
34 static DEFINE_SPINLOCK(tick_broadcast_lock);
35 static int tick_broadcast_force;
36
37 #ifdef CONFIG_TICK_ONESHOT
38 static void tick_broadcast_clear_oneshot(int cpu);
39 #else
40 static inline void tick_broadcast_clear_oneshot(int cpu) { }
41 #endif
42
43 /*
44 * Debugging: see timer_list.c
45 */
46 struct tick_device *tick_get_broadcast_device(void)
47 {
48 return &tick_broadcast_device;
49 }
50
51 struct cpumask *tick_get_broadcast_mask(void)
52 {
53 return to_cpumask(tick_broadcast_mask);
54 }
55
56 /*
57 * Start the device in periodic mode
58 */
59 static void tick_broadcast_start_periodic(struct clock_event_device *bc)
60 {
61 if (bc)
62 tick_setup_periodic(bc, 1);
63 }
64
65 /*
66 * Check, if the device can be utilized as broadcast device:
67 */
68 int tick_check_broadcast_device(struct clock_event_device *dev)
69 {
70 if ((tick_broadcast_device.evtdev &&
71 tick_broadcast_device.evtdev->rating >= dev->rating) ||
72 (dev->features & CLOCK_EVT_FEAT_C3STOP))
73 return 0;
74
75 clockevents_exchange_device(NULL, dev);
76 tick_broadcast_device.evtdev = dev;
77 if (!cpumask_empty(tick_get_broadcast_mask()))
78 tick_broadcast_start_periodic(dev);
79 return 1;
80 }
81
82 /*
83 * Check, if the device is the broadcast device
84 */
85 int tick_is_broadcast_device(struct clock_event_device *dev)
86 {
87 return (dev && tick_broadcast_device.evtdev == dev);
88 }
89
90 /*
91 * Check, if the device is disfunctional and a place holder, which
92 * needs to be handled by the broadcast device.
93 */
94 int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu)
95 {
96 unsigned long flags;
97 int ret = 0;
98
99 spin_lock_irqsave(&tick_broadcast_lock, flags);
100
101 /*
102 * Devices might be registered with both periodic and oneshot
103 * mode disabled. This signals, that the device needs to be
104 * operated from the broadcast device and is a placeholder for
105 * the cpu local device.
106 */
107 if (!tick_device_is_functional(dev)) {
108 dev->event_handler = tick_handle_periodic;
109 cpumask_set_cpu(cpu, tick_get_broadcast_mask());
110 tick_broadcast_start_periodic(tick_broadcast_device.evtdev);
111 ret = 1;
112 } else {
113 /*
114 * When the new device is not affected by the stop
115 * feature and the cpu is marked in the broadcast mask
116 * then clear the broadcast bit.
117 */
118 if (!(dev->features & CLOCK_EVT_FEAT_C3STOP)) {
119 int cpu = smp_processor_id();
120
121 cpumask_clear_cpu(cpu, tick_get_broadcast_mask());
122 tick_broadcast_clear_oneshot(cpu);
123 }
124 }
125 spin_unlock_irqrestore(&tick_broadcast_lock, flags);
126 return ret;
127 }
128
129 /*
130 * Broadcast the event to the cpus, which are set in the mask (mangled).
131 */
132 static void tick_do_broadcast(struct cpumask *mask)
133 {
134 int cpu = smp_processor_id();
135 struct tick_device *td;
136
137 /*
138 * Check, if the current cpu is in the mask
139 */
140 if (cpumask_test_cpu(cpu, mask)) {
141 cpumask_clear_cpu(cpu, mask);
142 td = &per_cpu(tick_cpu_device, cpu);
143 td->evtdev->event_handler(td->evtdev);
144 }
145
146 if (!cpumask_empty(mask)) {
147 /*
148 * It might be necessary to actually check whether the devices
149 * have different broadcast functions. For now, just use the
150 * one of the first device. This works as long as we have this
151 * misfeature only on x86 (lapic)
152 */
153 td = &per_cpu(tick_cpu_device, cpumask_first(mask));
154 td->evtdev->broadcast(mask);
155 }
156 }
157
158 /*
159 * Periodic broadcast:
160 * - invoke the broadcast handlers
161 */
162 static void tick_do_periodic_broadcast(void)
163 {
164 spin_lock(&tick_broadcast_lock);
165
166 cpumask_and(to_cpumask(tmpmask),
167 cpu_online_mask, tick_get_broadcast_mask());
168 tick_do_broadcast(to_cpumask(tmpmask));
169
170 spin_unlock(&tick_broadcast_lock);
171 }
172
173 /*
174 * Event handler for periodic broadcast ticks
175 */
176 static void tick_handle_periodic_broadcast(struct clock_event_device *dev)
177 {
178 ktime_t next;
179
180 tick_do_periodic_broadcast();
181
182 /*
183 * The device is in periodic mode. No reprogramming necessary:
184 */
185 if (dev->mode == CLOCK_EVT_MODE_PERIODIC)
186 return;
187
188 /*
189 * Setup the next period for devices, which do not have
190 * periodic mode. We read dev->next_event first and add to it
191 * when the event alrady expired. clockevents_program_event()
192 * sets dev->next_event only when the event is really
193 * programmed to the device.
194 */
195 for (next = dev->next_event; ;) {
196 next = ktime_add(next, tick_period);
197
198 if (!clockevents_program_event(dev, next, ktime_get()))
199 return;
200 tick_do_periodic_broadcast();
201 }
202 }
203
204 /*
205 * Powerstate information: The system enters/leaves a state, where
206 * affected devices might stop
207 */
208 static void tick_do_broadcast_on_off(unsigned long *reason)
209 {
210 struct clock_event_device *bc, *dev;
211 struct tick_device *td;
212 unsigned long flags;
213 int cpu, bc_stopped;
214
215 spin_lock_irqsave(&tick_broadcast_lock, flags);
216
217 cpu = smp_processor_id();
218 td = &per_cpu(tick_cpu_device, cpu);
219 dev = td->evtdev;
220 bc = tick_broadcast_device.evtdev;
221
222 /*
223 * Is the device not affected by the powerstate ?
224 */
225 if (!dev || !(dev->features & CLOCK_EVT_FEAT_C3STOP))
226 goto out;
227
228 if (!tick_device_is_functional(dev))
229 goto out;
230
231 bc_stopped = cpumask_empty(tick_get_broadcast_mask());
232
233 switch (*reason) {
234 case CLOCK_EVT_NOTIFY_BROADCAST_ON:
235 case CLOCK_EVT_NOTIFY_BROADCAST_FORCE:
236 if (!cpumask_test_cpu(cpu, tick_get_broadcast_mask())) {
237 cpumask_set_cpu(cpu, tick_get_broadcast_mask());
238 if (tick_broadcast_device.mode ==
239 TICKDEV_MODE_PERIODIC)
240 clockevents_shutdown(dev);
241 }
242 if (*reason == CLOCK_EVT_NOTIFY_BROADCAST_FORCE)
243 tick_broadcast_force = 1;
244 break;
245 case CLOCK_EVT_NOTIFY_BROADCAST_OFF:
246 if (!tick_broadcast_force &&
247 cpumask_test_cpu(cpu, tick_get_broadcast_mask())) {
248 cpumask_clear_cpu(cpu, tick_get_broadcast_mask());
249 if (tick_broadcast_device.mode ==
250 TICKDEV_MODE_PERIODIC)
251 tick_setup_periodic(dev, 0);
252 }
253 break;
254 }
255
256 if (cpumask_empty(tick_get_broadcast_mask())) {
257 if (!bc_stopped)
258 clockevents_shutdown(bc);
259 } else if (bc_stopped) {
260 if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
261 tick_broadcast_start_periodic(bc);
262 else
263 tick_broadcast_setup_oneshot(bc);
264 }
265 out:
266 spin_unlock_irqrestore(&tick_broadcast_lock, flags);
267 }
268
269 /*
270 * Powerstate information: The system enters/leaves a state, where
271 * affected devices might stop.
272 */
273 void tick_broadcast_on_off(unsigned long reason, int *oncpu)
274 {
275 if (!cpumask_test_cpu(*oncpu, cpu_online_mask))
276 printk(KERN_ERR "tick-broadcast: ignoring broadcast for "
277 "offline CPU #%d\n", *oncpu);
278 else
279 tick_do_broadcast_on_off(&reason);
280 }
281
282 /*
283 * Set the periodic handler depending on broadcast on/off
284 */
285 void tick_set_periodic_handler(struct clock_event_device *dev, int broadcast)
286 {
287 if (!broadcast)
288 dev->event_handler = tick_handle_periodic;
289 else
290 dev->event_handler = tick_handle_periodic_broadcast;
291 }
292
293 /*
294 * Remove a CPU from broadcasting
295 */
296 void tick_shutdown_broadcast(unsigned int *cpup)
297 {
298 struct clock_event_device *bc;
299 unsigned long flags;
300 unsigned int cpu = *cpup;
301
302 spin_lock_irqsave(&tick_broadcast_lock, flags);
303
304 bc = tick_broadcast_device.evtdev;
305 cpumask_clear_cpu(cpu, tick_get_broadcast_mask());
306
307 if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) {
308 if (bc && cpumask_empty(tick_get_broadcast_mask()))
309 clockevents_shutdown(bc);
310 }
311
312 spin_unlock_irqrestore(&tick_broadcast_lock, flags);
313 }
314
315 void tick_suspend_broadcast(void)
316 {
317 struct clock_event_device *bc;
318 unsigned long flags;
319
320 spin_lock_irqsave(&tick_broadcast_lock, flags);
321
322 bc = tick_broadcast_device.evtdev;
323 if (bc)
324 clockevents_shutdown(bc);
325
326 spin_unlock_irqrestore(&tick_broadcast_lock, flags);
327 }
328
329 int tick_resume_broadcast(void)
330 {
331 struct clock_event_device *bc;
332 unsigned long flags;
333 int broadcast = 0;
334
335 spin_lock_irqsave(&tick_broadcast_lock, flags);
336
337 bc = tick_broadcast_device.evtdev;
338
339 if (bc) {
340 clockevents_set_mode(bc, CLOCK_EVT_MODE_RESUME);
341
342 switch (tick_broadcast_device.mode) {
343 case TICKDEV_MODE_PERIODIC:
344 if (!cpumask_empty(tick_get_broadcast_mask()))
345 tick_broadcast_start_periodic(bc);
346 broadcast = cpumask_test_cpu(smp_processor_id(),
347 tick_get_broadcast_mask());
348 break;
349 case TICKDEV_MODE_ONESHOT:
350 broadcast = tick_resume_broadcast_oneshot(bc);
351 break;
352 }
353 }
354 spin_unlock_irqrestore(&tick_broadcast_lock, flags);
355
356 return broadcast;
357 }
358
359
360 #ifdef CONFIG_TICK_ONESHOT
361
362 /* FIXME: use cpumask_var_t. */
363 static DECLARE_BITMAP(tick_broadcast_oneshot_mask, NR_CPUS);
364
365 /*
366 * Exposed for debugging: see timer_list.c
367 */
368 struct cpumask *tick_get_broadcast_oneshot_mask(void)
369 {
370 return to_cpumask(tick_broadcast_oneshot_mask);
371 }
372
373 static int tick_broadcast_set_event(ktime_t expires, int force)
374 {
375 struct clock_event_device *bc = tick_broadcast_device.evtdev;
376
377 return tick_dev_program_event(bc, expires, force);
378 }
379
380 int tick_resume_broadcast_oneshot(struct clock_event_device *bc)
381 {
382 clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);
383 return 0;
384 }
385
386 /*
387 * Called from irq_enter() when idle was interrupted to reenable the
388 * per cpu device.
389 */
390 void tick_check_oneshot_broadcast(int cpu)
391 {
392 if (cpumask_test_cpu(cpu, to_cpumask(tick_broadcast_oneshot_mask))) {
393 struct tick_device *td = &per_cpu(tick_cpu_device, cpu);
394
395 clockevents_set_mode(td->evtdev, CLOCK_EVT_MODE_ONESHOT);
396 }
397 }
398
399 /*
400 * Handle oneshot mode broadcasting
401 */
402 static void tick_handle_oneshot_broadcast(struct clock_event_device *dev)
403 {
404 struct tick_device *td;
405 ktime_t now, next_event;
406 int cpu;
407
408 spin_lock(&tick_broadcast_lock);
409 again:
410 dev->next_event.tv64 = KTIME_MAX;
411 next_event.tv64 = KTIME_MAX;
412 cpumask_clear(to_cpumask(tmpmask));
413 now = ktime_get();
414 /* Find all expired events */
415 for_each_cpu(cpu, tick_get_broadcast_oneshot_mask()) {
416 td = &per_cpu(tick_cpu_device, cpu);
417 if (td->evtdev->next_event.tv64 <= now.tv64)
418 cpumask_set_cpu(cpu, to_cpumask(tmpmask));
419 else if (td->evtdev->next_event.tv64 < next_event.tv64)
420 next_event.tv64 = td->evtdev->next_event.tv64;
421 }
422
423 /*
424 * Wakeup the cpus which have an expired event.
425 */
426 tick_do_broadcast(to_cpumask(tmpmask));
427
428 /*
429 * Two reasons for reprogram:
430 *
431 * - The global event did not expire any CPU local
432 * events. This happens in dyntick mode, as the maximum PIT
433 * delta is quite small.
434 *
435 * - There are pending events on sleeping CPUs which were not
436 * in the event mask
437 */
438 if (next_event.tv64 != KTIME_MAX) {
439 /*
440 * Rearm the broadcast device. If event expired,
441 * repeat the above
442 */
443 if (tick_broadcast_set_event(next_event, 0))
444 goto again;
445 }
446 spin_unlock(&tick_broadcast_lock);
447 }
448
449 /*
450 * Powerstate information: The system enters/leaves a state, where
451 * affected devices might stop
452 */
453 void tick_broadcast_oneshot_control(unsigned long reason)
454 {
455 struct clock_event_device *bc, *dev;
456 struct tick_device *td;
457 unsigned long flags;
458 int cpu;
459
460 spin_lock_irqsave(&tick_broadcast_lock, flags);
461
462 /*
463 * Periodic mode does not care about the enter/exit of power
464 * states
465 */
466 if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
467 goto out;
468
469 bc = tick_broadcast_device.evtdev;
470 cpu = smp_processor_id();
471 td = &per_cpu(tick_cpu_device, cpu);
472 dev = td->evtdev;
473
474 if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
475 goto out;
476
477 if (reason == CLOCK_EVT_NOTIFY_BROADCAST_ENTER) {
478 if (!cpumask_test_cpu(cpu, tick_get_broadcast_oneshot_mask())) {
479 cpumask_set_cpu(cpu, tick_get_broadcast_oneshot_mask());
480 clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN);
481 if (dev->next_event.tv64 < bc->next_event.tv64)
482 tick_broadcast_set_event(dev->next_event, 1);
483 }
484 } else {
485 if (cpumask_test_cpu(cpu, tick_get_broadcast_oneshot_mask())) {
486 cpumask_clear_cpu(cpu,
487 tick_get_broadcast_oneshot_mask());
488 clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
489 if (dev->next_event.tv64 != KTIME_MAX)
490 tick_program_event(dev->next_event, 1);
491 }
492 }
493
494 out:
495 spin_unlock_irqrestore(&tick_broadcast_lock, flags);
496 }
497
498 /*
499 * Reset the one shot broadcast for a cpu
500 *
501 * Called with tick_broadcast_lock held
502 */
503 static void tick_broadcast_clear_oneshot(int cpu)
504 {
505 cpumask_clear_cpu(cpu, tick_get_broadcast_oneshot_mask());
506 }
507
508 static void tick_broadcast_init_next_event(struct cpumask *mask,
509 ktime_t expires)
510 {
511 struct tick_device *td;
512 int cpu;
513
514 for_each_cpu(cpu, mask) {
515 td = &per_cpu(tick_cpu_device, cpu);
516 if (td->evtdev)
517 td->evtdev->next_event = expires;
518 }
519 }
520
521 /**
522 * tick_broadcast_setup_oneshot - setup the broadcast device
523 */
524 void tick_broadcast_setup_oneshot(struct clock_event_device *bc)
525 {
526 /* Set it up only once ! */
527 if (bc->event_handler != tick_handle_oneshot_broadcast) {
528 int was_periodic = bc->mode == CLOCK_EVT_MODE_PERIODIC;
529 int cpu = smp_processor_id();
530
531 bc->event_handler = tick_handle_oneshot_broadcast;
532 clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);
533
534 /* Take the do_timer update */
535 tick_do_timer_cpu = cpu;
536
537 /*
538 * We must be careful here. There might be other CPUs
539 * waiting for periodic broadcast. We need to set the
540 * oneshot_mask bits for those and program the
541 * broadcast device to fire.
542 */
543 cpumask_copy(to_cpumask(tmpmask), tick_get_broadcast_mask());
544 cpumask_clear_cpu(cpu, to_cpumask(tmpmask));
545 cpumask_or(tick_get_broadcast_oneshot_mask(),
546 tick_get_broadcast_oneshot_mask(),
547 to_cpumask(tmpmask));
548
549 if (was_periodic && !cpumask_empty(to_cpumask(tmpmask))) {
550 tick_broadcast_init_next_event(to_cpumask(tmpmask),
551 tick_next_period);
552 tick_broadcast_set_event(tick_next_period, 1);
553 } else
554 bc->next_event.tv64 = KTIME_MAX;
555 }
556 }
557
558 /*
559 * Select oneshot operating mode for the broadcast device
560 */
561 void tick_broadcast_switch_to_oneshot(void)
562 {
563 struct clock_event_device *bc;
564 unsigned long flags;
565
566 spin_lock_irqsave(&tick_broadcast_lock, flags);
567
568 tick_broadcast_device.mode = TICKDEV_MODE_ONESHOT;
569 bc = tick_broadcast_device.evtdev;
570 if (bc)
571 tick_broadcast_setup_oneshot(bc);
572 spin_unlock_irqrestore(&tick_broadcast_lock, flags);
573 }
574
575
576 /*
577 * Remove a dead CPU from broadcasting
578 */
579 void tick_shutdown_broadcast_oneshot(unsigned int *cpup)
580 {
581 unsigned long flags;
582 unsigned int cpu = *cpup;
583
584 spin_lock_irqsave(&tick_broadcast_lock, flags);
585
586 /*
587 * Clear the broadcast mask flag for the dead cpu, but do not
588 * stop the broadcast device!
589 */
590 cpumask_clear_cpu(cpu, tick_get_broadcast_oneshot_mask());
591
592 spin_unlock_irqrestore(&tick_broadcast_lock, flags);
593 }
594
595 /*
596 * Check, whether the broadcast device is in one shot mode
597 */
598 int tick_broadcast_oneshot_active(void)
599 {
600 return tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT;
601 }
602
603 #endif
604
|
This page was automatically generated by the
LXR engine.
|