clockevents: fix periodic broadcast for oneshot devices
[linux-3.10.git] / 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/irq.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
34 #ifdef CONFIG_TICK_ONESHOT
35 static void tick_broadcast_clear_oneshot(int cpu);
36 #else
37 static inline void tick_broadcast_clear_oneshot(int cpu) { }
38 #endif
39
40 /*
41  * Debugging: see timer_list.c
42  */
43 struct tick_device *tick_get_broadcast_device(void)
44 {
45         return &tick_broadcast_device;
46 }
47
48 cpumask_t *tick_get_broadcast_mask(void)
49 {
50         return &tick_broadcast_mask;
51 }
52
53 /*
54  * Start the device in periodic mode
55  */
56 static void tick_broadcast_start_periodic(struct clock_event_device *bc)
57 {
58         if (bc)
59                 tick_setup_periodic(bc, 1);
60 }
61
62 /*
63  * Check, if the device can be utilized as broadcast device:
64  */
65 int tick_check_broadcast_device(struct clock_event_device *dev)
66 {
67         if (tick_broadcast_device.evtdev ||
68             (dev->features & CLOCK_EVT_FEAT_C3STOP))
69                 return 0;
70
71         clockevents_exchange_device(NULL, dev);
72         tick_broadcast_device.evtdev = dev;
73         if (!cpus_empty(tick_broadcast_mask))
74                 tick_broadcast_start_periodic(dev);
75         return 1;
76 }
77
78 /*
79  * Check, if the device is the broadcast device
80  */
81 int tick_is_broadcast_device(struct clock_event_device *dev)
82 {
83         return (dev && tick_broadcast_device.evtdev == dev);
84 }
85
86 /*
87  * Check, if the device is disfunctional and a place holder, which
88  * needs to be handled by the broadcast device.
89  */
90 int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu)
91 {
92         unsigned long flags;
93         int ret = 0;
94
95         spin_lock_irqsave(&tick_broadcast_lock, flags);
96
97         /*
98          * Devices might be registered with both periodic and oneshot
99          * mode disabled. This signals, that the device needs to be
100          * operated from the broadcast device and is a placeholder for
101          * the cpu local device.
102          */
103         if (!tick_device_is_functional(dev)) {
104                 dev->event_handler = tick_handle_periodic;
105                 cpu_set(cpu, tick_broadcast_mask);
106                 tick_broadcast_start_periodic(tick_broadcast_device.evtdev);
107                 ret = 1;
108         } else {
109                 /*
110                  * When the new device is not affected by the stop
111                  * feature and the cpu is marked in the broadcast mask
112                  * then clear the broadcast bit.
113                  */
114                 if (!(dev->features & CLOCK_EVT_FEAT_C3STOP)) {
115                         int cpu = smp_processor_id();
116
117                         cpu_clear(cpu, tick_broadcast_mask);
118                         tick_broadcast_clear_oneshot(cpu);
119                 }
120         }
121         spin_unlock_irqrestore(&tick_broadcast_lock, flags);
122         return ret;
123 }
124
125 /*
126  * Broadcast the event to the cpus, which are set in the mask
127  */
128 int tick_do_broadcast(cpumask_t mask)
129 {
130         int ret = 0, cpu = smp_processor_id();
131         struct tick_device *td;
132
133         /*
134          * Check, if the current cpu is in the mask
135          */
136         if (cpu_isset(cpu, mask)) {
137                 cpu_clear(cpu, mask);
138                 td = &per_cpu(tick_cpu_device, cpu);
139                 td->evtdev->event_handler(td->evtdev);
140                 ret = 1;
141         }
142
143         if (!cpus_empty(mask)) {
144                 /*
145                  * It might be necessary to actually check whether the devices
146                  * have different broadcast functions. For now, just use the
147                  * one of the first device. This works as long as we have this
148                  * misfeature only on x86 (lapic)
149                  */
150                 cpu = first_cpu(mask);
151                 td = &per_cpu(tick_cpu_device, cpu);
152                 td->evtdev->broadcast(mask);
153                 ret = 1;
154         }
155         return ret;
156 }
157
158 /*
159  * Periodic broadcast:
160  * - invoke the broadcast handlers
161  */
162 static void tick_do_periodic_broadcast(void)
163 {
164         cpumask_t mask;
165
166         spin_lock(&tick_broadcast_lock);
167
168         cpus_and(mask, cpu_online_map, tick_broadcast_mask);
169         tick_do_broadcast(mask);
170
171         spin_unlock(&tick_broadcast_lock);
172 }
173
174 /*
175  * Event handler for periodic broadcast ticks
176  */
177 static void tick_handle_periodic_broadcast(struct clock_event_device *dev)
178 {
179         tick_do_periodic_broadcast();
180
181         /*
182          * The device is in periodic mode. No reprogramming necessary:
183          */
184         if (dev->mode == CLOCK_EVT_MODE_PERIODIC)
185                 return;
186
187         /*
188          * Setup the next period for devices, which do not have
189          * periodic mode:
190          */
191         for (;;) {
192                 ktime_t next = ktime_add(dev->next_event, tick_period);
193
194                 if (!clockevents_program_event(dev, next, ktime_get()))
195                         return;
196                 tick_do_periodic_broadcast();
197         }
198 }
199
200 /*
201  * Powerstate information: The system enters/leaves a state, where
202  * affected devices might stop
203  */
204 static void tick_do_broadcast_on_off(void *why)
205 {
206         struct clock_event_device *bc, *dev;
207         struct tick_device *td;
208         unsigned long flags, *reason = why;
209         int cpu;
210
211         spin_lock_irqsave(&tick_broadcast_lock, flags);
212
213         cpu = smp_processor_id();
214         td = &per_cpu(tick_cpu_device, cpu);
215         dev = td->evtdev;
216         bc = tick_broadcast_device.evtdev;
217
218         /*
219          * Is the device in broadcast mode forever or is it not
220          * affected by the powerstate ?
221          */
222         if (!dev || !tick_device_is_functional(dev) ||
223             !(dev->features & CLOCK_EVT_FEAT_C3STOP))
224                 goto out;
225
226         if (*reason == CLOCK_EVT_NOTIFY_BROADCAST_ON) {
227                 if (!cpu_isset(cpu, tick_broadcast_mask)) {
228                         cpu_set(cpu, tick_broadcast_mask);
229                         if (td->mode == TICKDEV_MODE_PERIODIC)
230                                 clockevents_set_mode(dev,
231                                                      CLOCK_EVT_MODE_SHUTDOWN);
232                 }
233         } else {
234                 if (cpu_isset(cpu, tick_broadcast_mask)) {
235                         cpu_clear(cpu, tick_broadcast_mask);
236                         if (td->mode == TICKDEV_MODE_PERIODIC)
237                                 tick_setup_periodic(dev, 0);
238                 }
239         }
240
241         if (cpus_empty(tick_broadcast_mask))
242                 clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);
243         else {
244                 if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
245                         tick_broadcast_start_periodic(bc);
246                 else
247                         tick_broadcast_setup_oneshot(bc);
248         }
249 out:
250         spin_unlock_irqrestore(&tick_broadcast_lock, flags);
251 }
252
253 /*
254  * Powerstate information: The system enters/leaves a state, where
255  * affected devices might stop.
256  */
257 void tick_broadcast_on_off(unsigned long reason, int *oncpu)
258 {
259         int cpu = get_cpu();
260
261         if (!cpu_isset(*oncpu, cpu_online_map)) {
262                 printk(KERN_ERR "tick-braodcast: ignoring broadcast for "
263                        "offline CPU #%d\n", *oncpu);
264         } else {
265
266                 if (cpu == *oncpu)
267                         tick_do_broadcast_on_off(&reason);
268                 else
269                         smp_call_function_single(*oncpu,
270                                                  tick_do_broadcast_on_off,
271                                                  &reason, 1, 1);
272         }
273         put_cpu();
274 }
275
276 /*
277  * Set the periodic handler depending on broadcast on/off
278  */
279 void tick_set_periodic_handler(struct clock_event_device *dev, int broadcast)
280 {
281         if (!broadcast)
282                 dev->event_handler = tick_handle_periodic;
283         else
284                 dev->event_handler = tick_handle_periodic_broadcast;
285 }
286
287 /*
288  * Remove a CPU from broadcasting
289  */
290 void tick_shutdown_broadcast(unsigned int *cpup)
291 {
292         struct clock_event_device *bc;
293         unsigned long flags;
294         unsigned int cpu = *cpup;
295
296         spin_lock_irqsave(&tick_broadcast_lock, flags);
297
298         bc = tick_broadcast_device.evtdev;
299         cpu_clear(cpu, tick_broadcast_mask);
300
301         if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) {
302                 if (bc && cpus_empty(tick_broadcast_mask))
303                         clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);
304         }
305
306         spin_unlock_irqrestore(&tick_broadcast_lock, flags);
307 }
308
309 void tick_suspend_broadcast(void)
310 {
311         struct clock_event_device *bc;
312         unsigned long flags;
313
314         spin_lock_irqsave(&tick_broadcast_lock, flags);
315
316         bc = tick_broadcast_device.evtdev;
317         if (bc)
318                 clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);
319
320         spin_unlock_irqrestore(&tick_broadcast_lock, flags);
321 }
322
323 int tick_resume_broadcast(void)
324 {
325         struct clock_event_device *bc;
326         unsigned long flags;
327         int broadcast = 0;
328
329         spin_lock_irqsave(&tick_broadcast_lock, flags);
330
331         bc = tick_broadcast_device.evtdev;
332
333         if (bc) {
334                 clockevents_set_mode(bc, CLOCK_EVT_MODE_RESUME);
335
336                 switch (tick_broadcast_device.mode) {
337                 case TICKDEV_MODE_PERIODIC:
338                         if(!cpus_empty(tick_broadcast_mask))
339                                 tick_broadcast_start_periodic(bc);
340                         broadcast = cpu_isset(smp_processor_id(),
341                                               tick_broadcast_mask);
342                         break;
343                 case TICKDEV_MODE_ONESHOT:
344                         broadcast = tick_resume_broadcast_oneshot(bc);
345                         break;
346                 }
347         }
348         spin_unlock_irqrestore(&tick_broadcast_lock, flags);
349
350         return broadcast;
351 }
352
353
354 #ifdef CONFIG_TICK_ONESHOT
355
356 static cpumask_t tick_broadcast_oneshot_mask;
357
358 /*
359  * Debugging: see timer_list.c
360  */
361 cpumask_t *tick_get_broadcast_oneshot_mask(void)
362 {
363         return &tick_broadcast_oneshot_mask;
364 }
365
366 static int tick_broadcast_set_event(ktime_t expires, int force)
367 {
368         struct clock_event_device *bc = tick_broadcast_device.evtdev;
369         ktime_t now = ktime_get();
370         int res;
371
372         for(;;) {
373                 res = clockevents_program_event(bc, expires, now);
374                 if (!res || !force)
375                         return res;
376                 now = ktime_get();
377                 expires = ktime_add(now, ktime_set(0, bc->min_delta_ns));
378         }
379 }
380
381 int tick_resume_broadcast_oneshot(struct clock_event_device *bc)
382 {
383         clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);
384         return 0;
385 }
386
387 /*
388  * Reprogram the broadcast device:
389  *
390  * Called with tick_broadcast_lock held and interrupts disabled.
391  */
392 static int tick_broadcast_reprogram(void)
393 {
394         ktime_t expires = { .tv64 = KTIME_MAX };
395         struct tick_device *td;
396         int cpu;
397
398         /*
399          * Find the event which expires next:
400          */
401         for (cpu = first_cpu(tick_broadcast_oneshot_mask); cpu != NR_CPUS;
402              cpu = next_cpu(cpu, tick_broadcast_oneshot_mask)) {
403                 td = &per_cpu(tick_cpu_device, cpu);
404                 if (td->evtdev->next_event.tv64 < expires.tv64)
405                         expires = td->evtdev->next_event;
406         }
407
408         if (expires.tv64 == KTIME_MAX)
409                 return 0;
410
411         return tick_broadcast_set_event(expires, 0);
412 }
413
414 /*
415  * Handle oneshot mode broadcasting
416  */
417 static void tick_handle_oneshot_broadcast(struct clock_event_device *dev)
418 {
419         struct tick_device *td;
420         cpumask_t mask;
421         ktime_t now;
422         int cpu;
423
424         spin_lock(&tick_broadcast_lock);
425 again:
426         dev->next_event.tv64 = KTIME_MAX;
427         mask = CPU_MASK_NONE;
428         now = ktime_get();
429         /* Find all expired events */
430         for (cpu = first_cpu(tick_broadcast_oneshot_mask); cpu != NR_CPUS;
431              cpu = next_cpu(cpu, tick_broadcast_oneshot_mask)) {
432                 td = &per_cpu(tick_cpu_device, cpu);
433                 if (td->evtdev->next_event.tv64 <= now.tv64)
434                         cpu_set(cpu, mask);
435         }
436
437         /*
438          * Wakeup the cpus which have an expired event. The broadcast
439          * device is reprogrammed in the return from idle code.
440          */
441         if (!tick_do_broadcast(mask)) {
442                 /*
443                  * The global event did not expire any CPU local
444                  * events. This happens in dyntick mode, as the
445                  * maximum PIT delta is quite small.
446                  */
447                 if (tick_broadcast_reprogram())
448                         goto again;
449         }
450         spin_unlock(&tick_broadcast_lock);
451 }
452
453 /*
454  * Powerstate information: The system enters/leaves a state, where
455  * affected devices might stop
456  */
457 void tick_broadcast_oneshot_control(unsigned long reason)
458 {
459         struct clock_event_device *bc, *dev;
460         struct tick_device *td;
461         unsigned long flags;
462         int cpu;
463
464         spin_lock_irqsave(&tick_broadcast_lock, flags);
465
466         /*
467          * Periodic mode does not care about the enter/exit of power
468          * states
469          */
470         if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
471                 goto out;
472
473         bc = tick_broadcast_device.evtdev;
474         cpu = smp_processor_id();
475         td = &per_cpu(tick_cpu_device, cpu);
476         dev = td->evtdev;
477
478         if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
479                 goto out;
480
481         if (reason == CLOCK_EVT_NOTIFY_BROADCAST_ENTER) {
482                 if (!cpu_isset(cpu, tick_broadcast_oneshot_mask)) {
483                         cpu_set(cpu, tick_broadcast_oneshot_mask);
484                         clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN);
485                         if (dev->next_event.tv64 < bc->next_event.tv64)
486                                 tick_broadcast_set_event(dev->next_event, 1);
487                 }
488         } else {
489                 if (cpu_isset(cpu, tick_broadcast_oneshot_mask)) {
490                         cpu_clear(cpu, tick_broadcast_oneshot_mask);
491                         clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
492                         if (dev->next_event.tv64 != KTIME_MAX)
493                                 tick_program_event(dev->next_event, 1);
494                 }
495         }
496
497 out:
498         spin_unlock_irqrestore(&tick_broadcast_lock, flags);
499 }
500
501 /*
502  * Reset the one shot broadcast for a cpu
503  *
504  * Called with tick_broadcast_lock held
505  */
506 static void tick_broadcast_clear_oneshot(int cpu)
507 {
508         cpu_clear(cpu, tick_broadcast_oneshot_mask);
509 }
510
511 /**
512  * tick_broadcast_setup_highres - setup the broadcast device for highres
513  */
514 void tick_broadcast_setup_oneshot(struct clock_event_device *bc)
515 {
516         if (bc->mode != CLOCK_EVT_MODE_ONESHOT) {
517                 bc->event_handler = tick_handle_oneshot_broadcast;
518                 clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);
519                 bc->next_event.tv64 = KTIME_MAX;
520         }
521 }
522
523 /*
524  * Select oneshot operating mode for the broadcast device
525  */
526 void tick_broadcast_switch_to_oneshot(void)
527 {
528         struct clock_event_device *bc;
529         unsigned long flags;
530
531         spin_lock_irqsave(&tick_broadcast_lock, flags);
532
533         tick_broadcast_device.mode = TICKDEV_MODE_ONESHOT;
534         bc = tick_broadcast_device.evtdev;
535         if (bc)
536                 tick_broadcast_setup_oneshot(bc);
537         spin_unlock_irqrestore(&tick_broadcast_lock, flags);
538 }
539
540
541 /*
542  * Remove a dead CPU from broadcasting
543  */
544 void tick_shutdown_broadcast_oneshot(unsigned int *cpup)
545 {
546         unsigned long flags;
547         unsigned int cpu = *cpup;
548
549         spin_lock_irqsave(&tick_broadcast_lock, flags);
550
551         /*
552          * Clear the broadcast mask flag for the dead cpu, but do not
553          * stop the broadcast device!
554          */
555         cpu_clear(cpu, tick_broadcast_oneshot_mask);
556
557         spin_unlock_irqrestore(&tick_broadcast_lock, flags);
558 }
559
560 #endif