Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6
[linux-2.6] / kernel / time / tick-broadcast.c
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 struct tick_device tick_broadcast_device;
31 static cpumask_t tick_broadcast_mask;
32 static DEFINE_SPINLOCK(tick_broadcast_lock);
33 static int tick_broadcast_force;
34
35 #ifdef CONFIG_TICK_ONESHOT
36 static void tick_broadcast_clear_oneshot(int cpu);
37 #else
38 static inline void tick_broadcast_clear_oneshot(int cpu) { }
39 #endif
40
41 /*
42  * Debugging: see timer_list.c
43  */
44 struct tick_device *tick_get_broadcast_device(void)
45 {
46         return &tick_broadcast_device;
47 }
48
49 cpumask_t *tick_get_broadcast_mask(void)
50 {
51         return &tick_broadcast_mask;
52 }
53
54 /*
55  * Start the device in periodic mode
56  */
57 static void tick_broadcast_start_periodic(struct clock_event_device *bc)
58 {
59         if (bc)
60                 tick_setup_periodic(bc, 1);
61 }
62
63 /*
64  * Check, if the device can be utilized as broadcast device:
65  */
66 int tick_check_broadcast_device(struct clock_event_device *dev)
67 {
68         if ((tick_broadcast_device.evtdev &&
69              tick_broadcast_device.evtdev->rating >= dev->rating) ||
70              (dev->features & CLOCK_EVT_FEAT_C3STOP))
71                 return 0;
72
73         clockevents_exchange_device(NULL, dev);
74         tick_broadcast_device.evtdev = dev;
75         if (!cpus_empty(tick_broadcast_mask))
76                 tick_broadcast_start_periodic(dev);
77         return 1;
78 }
79
80 /*
81  * Check, if the device is the broadcast device
82  */
83 int tick_is_broadcast_device(struct clock_event_device *dev)
84 {
85         return (dev && tick_broadcast_device.evtdev == dev);
86 }
87
88 /*
89  * Check, if the device is disfunctional and a place holder, which
90  * needs to be handled by the broadcast device.
91  */
92 int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu)
93 {
94         unsigned long flags;
95         int ret = 0;
96
97         spin_lock_irqsave(&tick_broadcast_lock, flags);
98
99         /*
100          * Devices might be registered with both periodic and oneshot
101          * mode disabled. This signals, that the device needs to be
102          * operated from the broadcast device and is a placeholder for
103          * the cpu local device.
104          */
105         if (!tick_device_is_functional(dev)) {
106                 dev->event_handler = tick_handle_periodic;
107                 cpu_set(cpu, tick_broadcast_mask);
108                 tick_broadcast_start_periodic(tick_broadcast_device.evtdev);
109                 ret = 1;
110         } else {
111                 /*
112                  * When the new device is not affected by the stop
113                  * feature and the cpu is marked in the broadcast mask
114                  * then clear the broadcast bit.
115                  */
116                 if (!(dev->features & CLOCK_EVT_FEAT_C3STOP)) {
117                         int cpu = smp_processor_id();
118
119                         cpu_clear(cpu, tick_broadcast_mask);
120                         tick_broadcast_clear_oneshot(cpu);
121                 }
122         }
123         spin_unlock_irqrestore(&tick_broadcast_lock, flags);
124         return ret;
125 }
126
127 /*
128  * Broadcast the event to the cpus, which are set in the mask
129  */
130 static void tick_do_broadcast(cpumask_t mask)
131 {
132         int cpu = smp_processor_id();
133         struct tick_device *td;
134
135         /*
136          * Check, if the current cpu is in the mask
137          */
138         if (cpu_isset(cpu, mask)) {
139                 cpu_clear(cpu, mask);
140                 td = &per_cpu(tick_cpu_device, cpu);
141                 td->evtdev->event_handler(td->evtdev);
142         }
143
144         if (!cpus_empty(mask)) {
145                 /*
146                  * It might be necessary to actually check whether the devices
147                  * have different broadcast functions. For now, just use the
148                  * one of the first device. This works as long as we have this
149                  * misfeature only on x86 (lapic)
150                  */
151                 cpu = first_cpu(mask);
152                 td = &per_cpu(tick_cpu_device, cpu);
153                 td->evtdev->broadcast(mask);
154         }
155 }
156
157 /*
158  * Periodic broadcast:
159  * - invoke the broadcast handlers
160  */
161 static void tick_do_periodic_broadcast(void)
162 {
163         cpumask_t mask;
164
165         spin_lock(&tick_broadcast_lock);
166
167         cpus_and(mask, cpu_online_map, tick_broadcast_mask);
168         tick_do_broadcast(mask);
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(void *why)
209 {
210         struct clock_event_device *bc, *dev;
211         struct tick_device *td;
212         unsigned long flags, *reason = why;
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 = cpus_empty(tick_broadcast_mask);
232
233         switch (*reason) {
234         case CLOCK_EVT_NOTIFY_BROADCAST_ON:
235         case CLOCK_EVT_NOTIFY_BROADCAST_FORCE:
236                 if (!cpu_isset(cpu, tick_broadcast_mask)) {
237                         cpu_set(cpu, tick_broadcast_mask);
238                         if (bc->mode == TICKDEV_MODE_PERIODIC)
239                                 clockevents_shutdown(dev);
240                 }
241                 if (*reason == CLOCK_EVT_NOTIFY_BROADCAST_FORCE)
242                         tick_broadcast_force = 1;
243                 break;
244         case CLOCK_EVT_NOTIFY_BROADCAST_OFF:
245                 if (!tick_broadcast_force &&
246                     cpu_isset(cpu, tick_broadcast_mask)) {
247                         cpu_clear(cpu, tick_broadcast_mask);
248                         if (bc->mode == TICKDEV_MODE_PERIODIC)
249                                 tick_setup_periodic(dev, 0);
250                 }
251                 break;
252         }
253
254         if (cpus_empty(tick_broadcast_mask)) {
255                 if (!bc_stopped)
256                         clockevents_shutdown(bc);
257         } else if (bc_stopped) {
258                 if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
259                         tick_broadcast_start_periodic(bc);
260                 else
261                         tick_broadcast_setup_oneshot(bc);
262         }
263 out:
264         spin_unlock_irqrestore(&tick_broadcast_lock, flags);
265 }
266
267 /*
268  * Powerstate information: The system enters/leaves a state, where
269  * affected devices might stop.
270  */
271 void tick_broadcast_on_off(unsigned long reason, int *oncpu)
272 {
273         if (!cpu_isset(*oncpu, cpu_online_map))
274                 printk(KERN_ERR "tick-broadcast: ignoring broadcast for "
275                        "offline CPU #%d\n", *oncpu);
276         else
277                 smp_call_function_single(*oncpu, tick_do_broadcast_on_off,
278                                          &reason, 1);
279 }
280
281 /*
282  * Set the periodic handler depending on broadcast on/off
283  */
284 void tick_set_periodic_handler(struct clock_event_device *dev, int broadcast)
285 {
286         if (!broadcast)
287                 dev->event_handler = tick_handle_periodic;
288         else
289                 dev->event_handler = tick_handle_periodic_broadcast;
290 }
291
292 /*
293  * Remove a CPU from broadcasting
294  */
295 void tick_shutdown_broadcast(unsigned int *cpup)
296 {
297         struct clock_event_device *bc;
298         unsigned long flags;
299         unsigned int cpu = *cpup;
300
301         spin_lock_irqsave(&tick_broadcast_lock, flags);
302
303         bc = tick_broadcast_device.evtdev;
304         cpu_clear(cpu, tick_broadcast_mask);
305
306         if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) {
307                 if (bc && cpus_empty(tick_broadcast_mask))
308                         clockevents_shutdown(bc);
309         }
310
311         spin_unlock_irqrestore(&tick_broadcast_lock, flags);
312 }
313
314 void tick_suspend_broadcast(void)
315 {
316         struct clock_event_device *bc;
317         unsigned long flags;
318
319         spin_lock_irqsave(&tick_broadcast_lock, flags);
320
321         bc = tick_broadcast_device.evtdev;
322         if (bc)
323                 clockevents_shutdown(bc);
324
325         spin_unlock_irqrestore(&tick_broadcast_lock, flags);
326 }
327
328 int tick_resume_broadcast(void)
329 {
330         struct clock_event_device *bc;
331         unsigned long flags;
332         int broadcast = 0;
333
334         spin_lock_irqsave(&tick_broadcast_lock, flags);
335
336         bc = tick_broadcast_device.evtdev;
337
338         if (bc) {
339                 clockevents_set_mode(bc, CLOCK_EVT_MODE_RESUME);
340
341                 switch (tick_broadcast_device.mode) {
342                 case TICKDEV_MODE_PERIODIC:
343                         if(!cpus_empty(tick_broadcast_mask))
344                                 tick_broadcast_start_periodic(bc);
345                         broadcast = cpu_isset(smp_processor_id(),
346                                               tick_broadcast_mask);
347                         break;
348                 case TICKDEV_MODE_ONESHOT:
349                         broadcast = tick_resume_broadcast_oneshot(bc);
350                         break;
351                 }
352         }
353         spin_unlock_irqrestore(&tick_broadcast_lock, flags);
354
355         return broadcast;
356 }
357
358
359 #ifdef CONFIG_TICK_ONESHOT
360
361 static cpumask_t tick_broadcast_oneshot_mask;
362
363 /*
364  * Debugging: see timer_list.c
365  */
366 cpumask_t *tick_get_broadcast_oneshot_mask(void)
367 {
368         return &tick_broadcast_oneshot_mask;
369 }
370
371 static int tick_broadcast_set_event(ktime_t expires, int force)
372 {
373         struct clock_event_device *bc = tick_broadcast_device.evtdev;
374
375         return tick_dev_program_event(bc, expires, force);
376 }
377
378 int tick_resume_broadcast_oneshot(struct clock_event_device *bc)
379 {
380         clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);
381         return 0;
382 }
383
384 /*
385  * Handle oneshot mode broadcasting
386  */
387 static void tick_handle_oneshot_broadcast(struct clock_event_device *dev)
388 {
389         struct tick_device *td;
390         cpumask_t mask;
391         ktime_t now, next_event;
392         int cpu;
393
394         spin_lock(&tick_broadcast_lock);
395 again:
396         dev->next_event.tv64 = KTIME_MAX;
397         next_event.tv64 = KTIME_MAX;
398         mask = CPU_MASK_NONE;
399         now = ktime_get();
400         /* Find all expired events */
401         for_each_cpu_mask_nr(cpu, tick_broadcast_oneshot_mask) {
402                 td = &per_cpu(tick_cpu_device, cpu);
403                 if (td->evtdev->next_event.tv64 <= now.tv64)
404                         cpu_set(cpu, mask);
405                 else if (td->evtdev->next_event.tv64 < next_event.tv64)
406                         next_event.tv64 = td->evtdev->next_event.tv64;
407         }
408
409         /*
410          * Wakeup the cpus which have an expired event.
411          */
412         tick_do_broadcast(mask);
413
414         /*
415          * Two reasons for reprogram:
416          *
417          * - The global event did not expire any CPU local
418          * events. This happens in dyntick mode, as the maximum PIT
419          * delta is quite small.
420          *
421          * - There are pending events on sleeping CPUs which were not
422          * in the event mask
423          */
424         if (next_event.tv64 != KTIME_MAX) {
425                 /*
426                  * Rearm the broadcast device. If event expired,
427                  * repeat the above
428                  */
429                 if (tick_broadcast_set_event(next_event, 0))
430                         goto again;
431         }
432         spin_unlock(&tick_broadcast_lock);
433 }
434
435 /*
436  * Powerstate information: The system enters/leaves a state, where
437  * affected devices might stop
438  */
439 void tick_broadcast_oneshot_control(unsigned long reason)
440 {
441         struct clock_event_device *bc, *dev;
442         struct tick_device *td;
443         unsigned long flags;
444         int cpu;
445
446         spin_lock_irqsave(&tick_broadcast_lock, flags);
447
448         /*
449          * Periodic mode does not care about the enter/exit of power
450          * states
451          */
452         if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
453                 goto out;
454
455         bc = tick_broadcast_device.evtdev;
456         cpu = smp_processor_id();
457         td = &per_cpu(tick_cpu_device, cpu);
458         dev = td->evtdev;
459
460         if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
461                 goto out;
462
463         if (reason == CLOCK_EVT_NOTIFY_BROADCAST_ENTER) {
464                 if (!cpu_isset(cpu, tick_broadcast_oneshot_mask)) {
465                         cpu_set(cpu, tick_broadcast_oneshot_mask);
466                         clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN);
467                         if (dev->next_event.tv64 < bc->next_event.tv64)
468                                 tick_broadcast_set_event(dev->next_event, 1);
469                 }
470         } else {
471                 if (cpu_isset(cpu, tick_broadcast_oneshot_mask)) {
472                         cpu_clear(cpu, tick_broadcast_oneshot_mask);
473                         clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
474                         if (dev->next_event.tv64 != KTIME_MAX)
475                                 tick_program_event(dev->next_event, 1);
476                 }
477         }
478
479 out:
480         spin_unlock_irqrestore(&tick_broadcast_lock, flags);
481 }
482
483 /*
484  * Reset the one shot broadcast for a cpu
485  *
486  * Called with tick_broadcast_lock held
487  */
488 static void tick_broadcast_clear_oneshot(int cpu)
489 {
490         cpu_clear(cpu, tick_broadcast_oneshot_mask);
491 }
492
493 static void tick_broadcast_init_next_event(cpumask_t *mask, ktime_t expires)
494 {
495         struct tick_device *td;
496         int cpu;
497
498         for_each_cpu_mask_nr(cpu, *mask) {
499                 td = &per_cpu(tick_cpu_device, cpu);
500                 if (td->evtdev)
501                         td->evtdev->next_event = expires;
502         }
503 }
504
505 /**
506  * tick_broadcast_setup_oneshot - setup the broadcast device
507  */
508 void tick_broadcast_setup_oneshot(struct clock_event_device *bc)
509 {
510         /* Set it up only once ! */
511         if (bc->event_handler != tick_handle_oneshot_broadcast) {
512                 int was_periodic = bc->mode == CLOCK_EVT_MODE_PERIODIC;
513                 int cpu = smp_processor_id();
514                 cpumask_t mask;
515
516                 bc->event_handler = tick_handle_oneshot_broadcast;
517                 clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);
518
519                 /* Take the do_timer update */
520                 tick_do_timer_cpu = cpu;
521
522                 /*
523                  * We must be careful here. There might be other CPUs
524                  * waiting for periodic broadcast. We need to set the
525                  * oneshot_mask bits for those and program the
526                  * broadcast device to fire.
527                  */
528                 mask = tick_broadcast_mask;
529                 cpu_clear(cpu, mask);
530                 cpus_or(tick_broadcast_oneshot_mask,
531                         tick_broadcast_oneshot_mask, mask);
532
533                 if (was_periodic && !cpus_empty(mask)) {
534                         tick_broadcast_init_next_event(&mask, tick_next_period);
535                         tick_broadcast_set_event(tick_next_period, 1);
536                 } else
537                         bc->next_event.tv64 = KTIME_MAX;
538         }
539 }
540
541 /*
542  * Select oneshot operating mode for the broadcast device
543  */
544 void tick_broadcast_switch_to_oneshot(void)
545 {
546         struct clock_event_device *bc;
547         unsigned long flags;
548
549         spin_lock_irqsave(&tick_broadcast_lock, flags);
550
551         tick_broadcast_device.mode = TICKDEV_MODE_ONESHOT;
552         bc = tick_broadcast_device.evtdev;
553         if (bc)
554                 tick_broadcast_setup_oneshot(bc);
555         spin_unlock_irqrestore(&tick_broadcast_lock, flags);
556 }
557
558
559 /*
560  * Remove a dead CPU from broadcasting
561  */
562 void tick_shutdown_broadcast_oneshot(unsigned int *cpup)
563 {
564         unsigned long flags;
565         unsigned int cpu = *cpup;
566
567         spin_lock_irqsave(&tick_broadcast_lock, flags);
568
569         /*
570          * Clear the broadcast mask flag for the dead cpu, but do not
571          * stop the broadcast device!
572          */
573         cpu_clear(cpu, tick_broadcast_oneshot_mask);
574
575         spin_unlock_irqrestore(&tick_broadcast_lock, flags);
576 }
577
578 /*
579  * Check, whether the broadcast device is in one shot mode
580  */
581 int tick_broadcast_oneshot_active(void)
582 {
583         return tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT;
584 }
585
586 #endif