Commit | Line | Data |
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f8381cba TG |
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; | |
79bf2bb3 | 32 | static DEFINE_SPINLOCK(tick_broadcast_lock); |
f8381cba | 33 | |
5590a536 TG |
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 | ||
289f480a IM |
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 | ||
f8381cba TG |
53 | /* |
54 | * Start the device in periodic mode | |
55 | */ | |
56 | static void tick_broadcast_start_periodic(struct clock_event_device *bc) | |
57 | { | |
18de5bc4 | 58 | if (bc) |
f8381cba TG |
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 | { | |
4a93232d VP |
67 | if ((tick_broadcast_device.evtdev && |
68 | tick_broadcast_device.evtdev->rating >= dev->rating) || | |
69 | (dev->features & CLOCK_EVT_FEAT_C3STOP)) | |
f8381cba TG |
70 | return 0; |
71 | ||
72 | clockevents_exchange_device(NULL, dev); | |
73 | tick_broadcast_device.evtdev = dev; | |
74 | if (!cpus_empty(tick_broadcast_mask)) | |
75 | tick_broadcast_start_periodic(dev); | |
76 | return 1; | |
77 | } | |
78 | ||
79 | /* | |
80 | * Check, if the device is the broadcast device | |
81 | */ | |
82 | int tick_is_broadcast_device(struct clock_event_device *dev) | |
83 | { | |
84 | return (dev && tick_broadcast_device.evtdev == dev); | |
85 | } | |
86 | ||
87 | /* | |
88 | * Check, if the device is disfunctional and a place holder, which | |
89 | * needs to be handled by the broadcast device. | |
90 | */ | |
91 | int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu) | |
92 | { | |
93 | unsigned long flags; | |
94 | int ret = 0; | |
95 | ||
96 | spin_lock_irqsave(&tick_broadcast_lock, flags); | |
97 | ||
98 | /* | |
99 | * Devices might be registered with both periodic and oneshot | |
100 | * mode disabled. This signals, that the device needs to be | |
101 | * operated from the broadcast device and is a placeholder for | |
102 | * the cpu local device. | |
103 | */ | |
104 | if (!tick_device_is_functional(dev)) { | |
105 | dev->event_handler = tick_handle_periodic; | |
106 | cpu_set(cpu, tick_broadcast_mask); | |
107 | tick_broadcast_start_periodic(tick_broadcast_device.evtdev); | |
108 | ret = 1; | |
5590a536 TG |
109 | } else { |
110 | /* | |
111 | * When the new device is not affected by the stop | |
112 | * feature and the cpu is marked in the broadcast mask | |
113 | * then clear the broadcast bit. | |
114 | */ | |
115 | if (!(dev->features & CLOCK_EVT_FEAT_C3STOP)) { | |
116 | int cpu = smp_processor_id(); | |
f8381cba | 117 | |
5590a536 TG |
118 | cpu_clear(cpu, tick_broadcast_mask); |
119 | tick_broadcast_clear_oneshot(cpu); | |
120 | } | |
121 | } | |
f8381cba TG |
122 | spin_unlock_irqrestore(&tick_broadcast_lock, flags); |
123 | return ret; | |
124 | } | |
125 | ||
126 | /* | |
127 | * Broadcast the event to the cpus, which are set in the mask | |
128 | */ | |
129 | int tick_do_broadcast(cpumask_t mask) | |
130 | { | |
131 | int ret = 0, cpu = smp_processor_id(); | |
132 | struct tick_device *td; | |
133 | ||
134 | /* | |
135 | * Check, if the current cpu is in the mask | |
136 | */ | |
137 | if (cpu_isset(cpu, mask)) { | |
138 | cpu_clear(cpu, mask); | |
139 | td = &per_cpu(tick_cpu_device, cpu); | |
140 | td->evtdev->event_handler(td->evtdev); | |
141 | ret = 1; | |
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 | ret = 1; | |
155 | } | |
156 | return ret; | |
157 | } | |
158 | ||
159 | /* | |
160 | * Periodic broadcast: | |
161 | * - invoke the broadcast handlers | |
162 | */ | |
163 | static void tick_do_periodic_broadcast(void) | |
164 | { | |
165 | cpumask_t mask; | |
166 | ||
167 | spin_lock(&tick_broadcast_lock); | |
168 | ||
169 | cpus_and(mask, cpu_online_map, tick_broadcast_mask); | |
170 | tick_do_broadcast(mask); | |
171 | ||
172 | spin_unlock(&tick_broadcast_lock); | |
173 | } | |
174 | ||
175 | /* | |
176 | * Event handler for periodic broadcast ticks | |
177 | */ | |
178 | static void tick_handle_periodic_broadcast(struct clock_event_device *dev) | |
179 | { | |
f8381cba TG |
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: | |
191 | */ | |
192 | for (;;) { | |
193 | ktime_t next = ktime_add(dev->next_event, tick_period); | |
194 | ||
195 | if (!clockevents_program_event(dev, next, ktime_get())) | |
196 | return; | |
197 | tick_do_periodic_broadcast(); | |
198 | } | |
199 | } | |
200 | ||
201 | /* | |
202 | * Powerstate information: The system enters/leaves a state, where | |
203 | * affected devices might stop | |
204 | */ | |
205 | static void tick_do_broadcast_on_off(void *why) | |
206 | { | |
207 | struct clock_event_device *bc, *dev; | |
208 | struct tick_device *td; | |
209 | unsigned long flags, *reason = why; | |
210 | int cpu; | |
211 | ||
212 | spin_lock_irqsave(&tick_broadcast_lock, flags); | |
213 | ||
214 | cpu = smp_processor_id(); | |
215 | td = &per_cpu(tick_cpu_device, cpu); | |
216 | dev = td->evtdev; | |
217 | bc = tick_broadcast_device.evtdev; | |
218 | ||
219 | /* | |
220 | * Is the device in broadcast mode forever or is it not | |
221 | * affected by the powerstate ? | |
222 | */ | |
223 | if (!dev || !tick_device_is_functional(dev) || | |
224 | !(dev->features & CLOCK_EVT_FEAT_C3STOP)) | |
225 | goto out; | |
226 | ||
227 | if (*reason == CLOCK_EVT_NOTIFY_BROADCAST_ON) { | |
228 | if (!cpu_isset(cpu, tick_broadcast_mask)) { | |
229 | cpu_set(cpu, tick_broadcast_mask); | |
230 | if (td->mode == TICKDEV_MODE_PERIODIC) | |
231 | clockevents_set_mode(dev, | |
232 | CLOCK_EVT_MODE_SHUTDOWN); | |
233 | } | |
234 | } else { | |
235 | if (cpu_isset(cpu, tick_broadcast_mask)) { | |
236 | cpu_clear(cpu, tick_broadcast_mask); | |
237 | if (td->mode == TICKDEV_MODE_PERIODIC) | |
238 | tick_setup_periodic(dev, 0); | |
239 | } | |
240 | } | |
241 | ||
242 | if (cpus_empty(tick_broadcast_mask)) | |
243 | clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN); | |
244 | else { | |
245 | if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) | |
246 | tick_broadcast_start_periodic(bc); | |
79bf2bb3 TG |
247 | else |
248 | tick_broadcast_setup_oneshot(bc); | |
f8381cba TG |
249 | } |
250 | out: | |
251 | spin_unlock_irqrestore(&tick_broadcast_lock, flags); | |
252 | } | |
253 | ||
254 | /* | |
255 | * Powerstate information: The system enters/leaves a state, where | |
256 | * affected devices might stop. | |
257 | */ | |
258 | void tick_broadcast_on_off(unsigned long reason, int *oncpu) | |
259 | { | |
260 | int cpu = get_cpu(); | |
261 | ||
72fcde96 TG |
262 | if (!cpu_isset(*oncpu, cpu_online_map)) { |
263 | printk(KERN_ERR "tick-braodcast: ignoring broadcast for " | |
264 | "offline CPU #%d\n", *oncpu); | |
265 | } else { | |
266 | ||
267 | if (cpu == *oncpu) | |
268 | tick_do_broadcast_on_off(&reason); | |
269 | else | |
270 | smp_call_function_single(*oncpu, | |
271 | tick_do_broadcast_on_off, | |
272 | &reason, 1, 1); | |
273 | } | |
f8381cba TG |
274 | put_cpu(); |
275 | } | |
276 | ||
277 | /* | |
278 | * Set the periodic handler depending on broadcast on/off | |
279 | */ | |
280 | void tick_set_periodic_handler(struct clock_event_device *dev, int broadcast) | |
281 | { | |
282 | if (!broadcast) | |
283 | dev->event_handler = tick_handle_periodic; | |
284 | else | |
285 | dev->event_handler = tick_handle_periodic_broadcast; | |
286 | } | |
287 | ||
288 | /* | |
289 | * Remove a CPU from broadcasting | |
290 | */ | |
291 | void tick_shutdown_broadcast(unsigned int *cpup) | |
292 | { | |
293 | struct clock_event_device *bc; | |
294 | unsigned long flags; | |
295 | unsigned int cpu = *cpup; | |
296 | ||
297 | spin_lock_irqsave(&tick_broadcast_lock, flags); | |
298 | ||
299 | bc = tick_broadcast_device.evtdev; | |
300 | cpu_clear(cpu, tick_broadcast_mask); | |
301 | ||
302 | if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) { | |
303 | if (bc && cpus_empty(tick_broadcast_mask)) | |
304 | clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN); | |
305 | } | |
306 | ||
307 | spin_unlock_irqrestore(&tick_broadcast_lock, flags); | |
308 | } | |
79bf2bb3 | 309 | |
6321dd60 TG |
310 | void tick_suspend_broadcast(void) |
311 | { | |
312 | struct clock_event_device *bc; | |
313 | unsigned long flags; | |
314 | ||
315 | spin_lock_irqsave(&tick_broadcast_lock, flags); | |
316 | ||
317 | bc = tick_broadcast_device.evtdev; | |
18de5bc4 | 318 | if (bc) |
6321dd60 TG |
319 | clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN); |
320 | ||
321 | spin_unlock_irqrestore(&tick_broadcast_lock, flags); | |
322 | } | |
323 | ||
324 | int tick_resume_broadcast(void) | |
325 | { | |
326 | struct clock_event_device *bc; | |
327 | unsigned long flags; | |
328 | int broadcast = 0; | |
329 | ||
330 | spin_lock_irqsave(&tick_broadcast_lock, flags); | |
331 | ||
332 | bc = tick_broadcast_device.evtdev; | |
6321dd60 | 333 | |
cd05a1f8 | 334 | if (bc) { |
18de5bc4 TG |
335 | clockevents_set_mode(bc, CLOCK_EVT_MODE_RESUME); |
336 | ||
cd05a1f8 TG |
337 | switch (tick_broadcast_device.mode) { |
338 | case TICKDEV_MODE_PERIODIC: | |
339 | if(!cpus_empty(tick_broadcast_mask)) | |
340 | tick_broadcast_start_periodic(bc); | |
341 | broadcast = cpu_isset(smp_processor_id(), | |
342 | tick_broadcast_mask); | |
343 | break; | |
344 | case TICKDEV_MODE_ONESHOT: | |
345 | broadcast = tick_resume_broadcast_oneshot(bc); | |
346 | break; | |
347 | } | |
6321dd60 TG |
348 | } |
349 | spin_unlock_irqrestore(&tick_broadcast_lock, flags); | |
350 | ||
351 | return broadcast; | |
352 | } | |
353 | ||
354 | ||
79bf2bb3 TG |
355 | #ifdef CONFIG_TICK_ONESHOT |
356 | ||
357 | static cpumask_t tick_broadcast_oneshot_mask; | |
358 | ||
289f480a IM |
359 | /* |
360 | * Debugging: see timer_list.c | |
361 | */ | |
362 | cpumask_t *tick_get_broadcast_oneshot_mask(void) | |
363 | { | |
364 | return &tick_broadcast_oneshot_mask; | |
365 | } | |
366 | ||
79bf2bb3 TG |
367 | static int tick_broadcast_set_event(ktime_t expires, int force) |
368 | { | |
369 | struct clock_event_device *bc = tick_broadcast_device.evtdev; | |
370 | ktime_t now = ktime_get(); | |
371 | int res; | |
372 | ||
373 | for(;;) { | |
374 | res = clockevents_program_event(bc, expires, now); | |
375 | if (!res || !force) | |
376 | return res; | |
377 | now = ktime_get(); | |
378 | expires = ktime_add(now, ktime_set(0, bc->min_delta_ns)); | |
379 | } | |
380 | } | |
381 | ||
cd05a1f8 TG |
382 | int tick_resume_broadcast_oneshot(struct clock_event_device *bc) |
383 | { | |
384 | clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT); | |
b7e113dc | 385 | return 0; |
cd05a1f8 TG |
386 | } |
387 | ||
79bf2bb3 TG |
388 | /* |
389 | * Reprogram the broadcast device: | |
390 | * | |
391 | * Called with tick_broadcast_lock held and interrupts disabled. | |
392 | */ | |
393 | static int tick_broadcast_reprogram(void) | |
394 | { | |
395 | ktime_t expires = { .tv64 = KTIME_MAX }; | |
396 | struct tick_device *td; | |
397 | int cpu; | |
398 | ||
399 | /* | |
400 | * Find the event which expires next: | |
401 | */ | |
402 | for (cpu = first_cpu(tick_broadcast_oneshot_mask); cpu != NR_CPUS; | |
403 | cpu = next_cpu(cpu, tick_broadcast_oneshot_mask)) { | |
404 | td = &per_cpu(tick_cpu_device, cpu); | |
405 | if (td->evtdev->next_event.tv64 < expires.tv64) | |
406 | expires = td->evtdev->next_event; | |
407 | } | |
408 | ||
409 | if (expires.tv64 == KTIME_MAX) | |
410 | return 0; | |
411 | ||
412 | return tick_broadcast_set_event(expires, 0); | |
413 | } | |
414 | ||
415 | /* | |
416 | * Handle oneshot mode broadcasting | |
417 | */ | |
418 | static void tick_handle_oneshot_broadcast(struct clock_event_device *dev) | |
419 | { | |
420 | struct tick_device *td; | |
421 | cpumask_t mask; | |
422 | ktime_t now; | |
423 | int cpu; | |
424 | ||
425 | spin_lock(&tick_broadcast_lock); | |
426 | again: | |
427 | dev->next_event.tv64 = KTIME_MAX; | |
428 | mask = CPU_MASK_NONE; | |
429 | now = ktime_get(); | |
430 | /* Find all expired events */ | |
431 | for (cpu = first_cpu(tick_broadcast_oneshot_mask); cpu != NR_CPUS; | |
432 | cpu = next_cpu(cpu, tick_broadcast_oneshot_mask)) { | |
433 | td = &per_cpu(tick_cpu_device, cpu); | |
434 | if (td->evtdev->next_event.tv64 <= now.tv64) | |
435 | cpu_set(cpu, mask); | |
436 | } | |
437 | ||
438 | /* | |
439 | * Wakeup the cpus which have an expired event. The broadcast | |
440 | * device is reprogrammed in the return from idle code. | |
441 | */ | |
442 | if (!tick_do_broadcast(mask)) { | |
443 | /* | |
444 | * The global event did not expire any CPU local | |
445 | * events. This happens in dyntick mode, as the | |
446 | * maximum PIT delta is quite small. | |
447 | */ | |
448 | if (tick_broadcast_reprogram()) | |
449 | goto again; | |
450 | } | |
451 | spin_unlock(&tick_broadcast_lock); | |
452 | } | |
453 | ||
454 | /* | |
455 | * Powerstate information: The system enters/leaves a state, where | |
456 | * affected devices might stop | |
457 | */ | |
458 | void tick_broadcast_oneshot_control(unsigned long reason) | |
459 | { | |
460 | struct clock_event_device *bc, *dev; | |
461 | struct tick_device *td; | |
462 | unsigned long flags; | |
463 | int cpu; | |
464 | ||
465 | spin_lock_irqsave(&tick_broadcast_lock, flags); | |
466 | ||
467 | /* | |
468 | * Periodic mode does not care about the enter/exit of power | |
469 | * states | |
470 | */ | |
471 | if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) | |
472 | goto out; | |
473 | ||
474 | bc = tick_broadcast_device.evtdev; | |
475 | cpu = smp_processor_id(); | |
476 | td = &per_cpu(tick_cpu_device, cpu); | |
477 | dev = td->evtdev; | |
478 | ||
479 | if (!(dev->features & CLOCK_EVT_FEAT_C3STOP)) | |
480 | goto out; | |
481 | ||
482 | if (reason == CLOCK_EVT_NOTIFY_BROADCAST_ENTER) { | |
483 | if (!cpu_isset(cpu, tick_broadcast_oneshot_mask)) { | |
484 | cpu_set(cpu, tick_broadcast_oneshot_mask); | |
485 | clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN); | |
486 | if (dev->next_event.tv64 < bc->next_event.tv64) | |
487 | tick_broadcast_set_event(dev->next_event, 1); | |
488 | } | |
489 | } else { | |
490 | if (cpu_isset(cpu, tick_broadcast_oneshot_mask)) { | |
491 | cpu_clear(cpu, tick_broadcast_oneshot_mask); | |
492 | clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT); | |
493 | if (dev->next_event.tv64 != KTIME_MAX) | |
494 | tick_program_event(dev->next_event, 1); | |
495 | } | |
496 | } | |
497 | ||
498 | out: | |
499 | spin_unlock_irqrestore(&tick_broadcast_lock, flags); | |
500 | } | |
501 | ||
5590a536 TG |
502 | /* |
503 | * Reset the one shot broadcast for a cpu | |
504 | * | |
505 | * Called with tick_broadcast_lock held | |
506 | */ | |
507 | static void tick_broadcast_clear_oneshot(int cpu) | |
508 | { | |
509 | cpu_clear(cpu, tick_broadcast_oneshot_mask); | |
510 | } | |
511 | ||
79bf2bb3 TG |
512 | /** |
513 | * tick_broadcast_setup_highres - setup the broadcast device for highres | |
514 | */ | |
515 | void tick_broadcast_setup_oneshot(struct clock_event_device *bc) | |
516 | { | |
4a93232d VP |
517 | bc->event_handler = tick_handle_oneshot_broadcast; |
518 | clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT); | |
519 | bc->next_event.tv64 = KTIME_MAX; | |
79bf2bb3 TG |
520 | } |
521 | ||
522 | /* | |
523 | * Select oneshot operating mode for the broadcast device | |
524 | */ | |
525 | void tick_broadcast_switch_to_oneshot(void) | |
526 | { | |
527 | struct clock_event_device *bc; | |
528 | unsigned long flags; | |
529 | ||
530 | spin_lock_irqsave(&tick_broadcast_lock, flags); | |
531 | ||
532 | tick_broadcast_device.mode = TICKDEV_MODE_ONESHOT; | |
533 | bc = tick_broadcast_device.evtdev; | |
534 | if (bc) | |
535 | tick_broadcast_setup_oneshot(bc); | |
536 | spin_unlock_irqrestore(&tick_broadcast_lock, flags); | |
537 | } | |
538 | ||
539 | ||
540 | /* | |
541 | * Remove a dead CPU from broadcasting | |
542 | */ | |
543 | void tick_shutdown_broadcast_oneshot(unsigned int *cpup) | |
544 | { | |
79bf2bb3 TG |
545 | unsigned long flags; |
546 | unsigned int cpu = *cpup; | |
547 | ||
548 | spin_lock_irqsave(&tick_broadcast_lock, flags); | |
549 | ||
31d9b393 TG |
550 | /* |
551 | * Clear the broadcast mask flag for the dead cpu, but do not | |
552 | * stop the broadcast device! | |
553 | */ | |
79bf2bb3 TG |
554 | cpu_clear(cpu, tick_broadcast_oneshot_mask); |
555 | ||
79bf2bb3 TG |
556 | spin_unlock_irqrestore(&tick_broadcast_lock, flags); |
557 | } | |
558 | ||
559 | #endif |