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 | |
289f480a IM |
34 | /* |
35 | * Debugging: see timer_list.c | |
36 | */ | |
37 | struct tick_device *tick_get_broadcast_device(void) | |
38 | { | |
39 | return &tick_broadcast_device; | |
40 | } | |
41 | ||
42 | cpumask_t *tick_get_broadcast_mask(void) | |
43 | { | |
44 | return &tick_broadcast_mask; | |
45 | } | |
46 | ||
f8381cba TG |
47 | /* |
48 | * Start the device in periodic mode | |
49 | */ | |
50 | static void tick_broadcast_start_periodic(struct clock_event_device *bc) | |
51 | { | |
52 | if (bc && bc->mode == CLOCK_EVT_MODE_SHUTDOWN) | |
53 | tick_setup_periodic(bc, 1); | |
54 | } | |
55 | ||
56 | /* | |
57 | * Check, if the device can be utilized as broadcast device: | |
58 | */ | |
59 | int tick_check_broadcast_device(struct clock_event_device *dev) | |
60 | { | |
61 | if (tick_broadcast_device.evtdev || | |
62 | (dev->features & CLOCK_EVT_FEAT_C3STOP)) | |
63 | return 0; | |
64 | ||
65 | clockevents_exchange_device(NULL, dev); | |
66 | tick_broadcast_device.evtdev = dev; | |
67 | if (!cpus_empty(tick_broadcast_mask)) | |
68 | tick_broadcast_start_periodic(dev); | |
69 | return 1; | |
70 | } | |
71 | ||
72 | /* | |
73 | * Check, if the device is the broadcast device | |
74 | */ | |
75 | int tick_is_broadcast_device(struct clock_event_device *dev) | |
76 | { | |
77 | return (dev && tick_broadcast_device.evtdev == dev); | |
78 | } | |
79 | ||
80 | /* | |
81 | * Check, if the device is disfunctional and a place holder, which | |
82 | * needs to be handled by the broadcast device. | |
83 | */ | |
84 | int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu) | |
85 | { | |
86 | unsigned long flags; | |
87 | int ret = 0; | |
88 | ||
89 | spin_lock_irqsave(&tick_broadcast_lock, flags); | |
90 | ||
91 | /* | |
92 | * Devices might be registered with both periodic and oneshot | |
93 | * mode disabled. This signals, that the device needs to be | |
94 | * operated from the broadcast device and is a placeholder for | |
95 | * the cpu local device. | |
96 | */ | |
97 | if (!tick_device_is_functional(dev)) { | |
98 | dev->event_handler = tick_handle_periodic; | |
99 | cpu_set(cpu, tick_broadcast_mask); | |
100 | tick_broadcast_start_periodic(tick_broadcast_device.evtdev); | |
101 | ret = 1; | |
102 | } | |
103 | ||
104 | spin_unlock_irqrestore(&tick_broadcast_lock, flags); | |
105 | return ret; | |
106 | } | |
107 | ||
108 | /* | |
109 | * Broadcast the event to the cpus, which are set in the mask | |
110 | */ | |
111 | int tick_do_broadcast(cpumask_t mask) | |
112 | { | |
113 | int ret = 0, cpu = smp_processor_id(); | |
114 | struct tick_device *td; | |
115 | ||
116 | /* | |
117 | * Check, if the current cpu is in the mask | |
118 | */ | |
119 | if (cpu_isset(cpu, mask)) { | |
120 | cpu_clear(cpu, mask); | |
121 | td = &per_cpu(tick_cpu_device, cpu); | |
122 | td->evtdev->event_handler(td->evtdev); | |
123 | ret = 1; | |
124 | } | |
125 | ||
126 | if (!cpus_empty(mask)) { | |
127 | /* | |
128 | * It might be necessary to actually check whether the devices | |
129 | * have different broadcast functions. For now, just use the | |
130 | * one of the first device. This works as long as we have this | |
131 | * misfeature only on x86 (lapic) | |
132 | */ | |
133 | cpu = first_cpu(mask); | |
134 | td = &per_cpu(tick_cpu_device, cpu); | |
135 | td->evtdev->broadcast(mask); | |
136 | ret = 1; | |
137 | } | |
138 | return ret; | |
139 | } | |
140 | ||
141 | /* | |
142 | * Periodic broadcast: | |
143 | * - invoke the broadcast handlers | |
144 | */ | |
145 | static void tick_do_periodic_broadcast(void) | |
146 | { | |
147 | cpumask_t mask; | |
148 | ||
149 | spin_lock(&tick_broadcast_lock); | |
150 | ||
151 | cpus_and(mask, cpu_online_map, tick_broadcast_mask); | |
152 | tick_do_broadcast(mask); | |
153 | ||
154 | spin_unlock(&tick_broadcast_lock); | |
155 | } | |
156 | ||
157 | /* | |
158 | * Event handler for periodic broadcast ticks | |
159 | */ | |
160 | static void tick_handle_periodic_broadcast(struct clock_event_device *dev) | |
161 | { | |
162 | dev->next_event.tv64 = KTIME_MAX; | |
163 | ||
164 | tick_do_periodic_broadcast(); | |
165 | ||
166 | /* | |
167 | * The device is in periodic mode. No reprogramming necessary: | |
168 | */ | |
169 | if (dev->mode == CLOCK_EVT_MODE_PERIODIC) | |
170 | return; | |
171 | ||
172 | /* | |
173 | * Setup the next period for devices, which do not have | |
174 | * periodic mode: | |
175 | */ | |
176 | for (;;) { | |
177 | ktime_t next = ktime_add(dev->next_event, tick_period); | |
178 | ||
179 | if (!clockevents_program_event(dev, next, ktime_get())) | |
180 | return; | |
181 | tick_do_periodic_broadcast(); | |
182 | } | |
183 | } | |
184 | ||
185 | /* | |
186 | * Powerstate information: The system enters/leaves a state, where | |
187 | * affected devices might stop | |
188 | */ | |
189 | static void tick_do_broadcast_on_off(void *why) | |
190 | { | |
191 | struct clock_event_device *bc, *dev; | |
192 | struct tick_device *td; | |
193 | unsigned long flags, *reason = why; | |
194 | int cpu; | |
195 | ||
196 | spin_lock_irqsave(&tick_broadcast_lock, flags); | |
197 | ||
198 | cpu = smp_processor_id(); | |
199 | td = &per_cpu(tick_cpu_device, cpu); | |
200 | dev = td->evtdev; | |
201 | bc = tick_broadcast_device.evtdev; | |
202 | ||
203 | /* | |
204 | * Is the device in broadcast mode forever or is it not | |
205 | * affected by the powerstate ? | |
206 | */ | |
207 | if (!dev || !tick_device_is_functional(dev) || | |
208 | !(dev->features & CLOCK_EVT_FEAT_C3STOP)) | |
209 | goto out; | |
210 | ||
211 | if (*reason == CLOCK_EVT_NOTIFY_BROADCAST_ON) { | |
212 | if (!cpu_isset(cpu, tick_broadcast_mask)) { | |
213 | cpu_set(cpu, tick_broadcast_mask); | |
214 | if (td->mode == TICKDEV_MODE_PERIODIC) | |
215 | clockevents_set_mode(dev, | |
216 | CLOCK_EVT_MODE_SHUTDOWN); | |
217 | } | |
218 | } else { | |
219 | if (cpu_isset(cpu, tick_broadcast_mask)) { | |
220 | cpu_clear(cpu, tick_broadcast_mask); | |
221 | if (td->mode == TICKDEV_MODE_PERIODIC) | |
222 | tick_setup_periodic(dev, 0); | |
223 | } | |
224 | } | |
225 | ||
226 | if (cpus_empty(tick_broadcast_mask)) | |
227 | clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN); | |
228 | else { | |
229 | if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) | |
230 | tick_broadcast_start_periodic(bc); | |
79bf2bb3 TG |
231 | else |
232 | tick_broadcast_setup_oneshot(bc); | |
f8381cba TG |
233 | } |
234 | out: | |
235 | spin_unlock_irqrestore(&tick_broadcast_lock, flags); | |
236 | } | |
237 | ||
238 | /* | |
239 | * Powerstate information: The system enters/leaves a state, where | |
240 | * affected devices might stop. | |
241 | */ | |
242 | void tick_broadcast_on_off(unsigned long reason, int *oncpu) | |
243 | { | |
244 | int cpu = get_cpu(); | |
245 | ||
246 | if (cpu == *oncpu) | |
247 | tick_do_broadcast_on_off(&reason); | |
248 | else | |
249 | smp_call_function_single(*oncpu, tick_do_broadcast_on_off, | |
250 | &reason, 1, 1); | |
251 | put_cpu(); | |
252 | } | |
253 | ||
254 | /* | |
255 | * Set the periodic handler depending on broadcast on/off | |
256 | */ | |
257 | void tick_set_periodic_handler(struct clock_event_device *dev, int broadcast) | |
258 | { | |
259 | if (!broadcast) | |
260 | dev->event_handler = tick_handle_periodic; | |
261 | else | |
262 | dev->event_handler = tick_handle_periodic_broadcast; | |
263 | } | |
264 | ||
265 | /* | |
266 | * Remove a CPU from broadcasting | |
267 | */ | |
268 | void tick_shutdown_broadcast(unsigned int *cpup) | |
269 | { | |
270 | struct clock_event_device *bc; | |
271 | unsigned long flags; | |
272 | unsigned int cpu = *cpup; | |
273 | ||
274 | spin_lock_irqsave(&tick_broadcast_lock, flags); | |
275 | ||
276 | bc = tick_broadcast_device.evtdev; | |
277 | cpu_clear(cpu, tick_broadcast_mask); | |
278 | ||
279 | if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) { | |
280 | if (bc && cpus_empty(tick_broadcast_mask)) | |
281 | clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN); | |
282 | } | |
283 | ||
284 | spin_unlock_irqrestore(&tick_broadcast_lock, flags); | |
285 | } | |
79bf2bb3 | 286 | |
6321dd60 TG |
287 | void tick_suspend_broadcast(void) |
288 | { | |
289 | struct clock_event_device *bc; | |
290 | unsigned long flags; | |
291 | ||
292 | spin_lock_irqsave(&tick_broadcast_lock, flags); | |
293 | ||
294 | bc = tick_broadcast_device.evtdev; | |
295 | if (bc && tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) | |
296 | clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN); | |
297 | ||
298 | spin_unlock_irqrestore(&tick_broadcast_lock, flags); | |
299 | } | |
300 | ||
301 | int tick_resume_broadcast(void) | |
302 | { | |
303 | struct clock_event_device *bc; | |
304 | unsigned long flags; | |
305 | int broadcast = 0; | |
306 | ||
307 | spin_lock_irqsave(&tick_broadcast_lock, flags); | |
308 | ||
309 | bc = tick_broadcast_device.evtdev; | |
310 | if (bc) { | |
311 | if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC && | |
312 | !cpus_empty(tick_broadcast_mask)) | |
313 | tick_broadcast_start_periodic(bc); | |
314 | ||
315 | broadcast = cpu_isset(smp_processor_id(), tick_broadcast_mask); | |
316 | } | |
317 | spin_unlock_irqrestore(&tick_broadcast_lock, flags); | |
318 | ||
319 | return broadcast; | |
320 | } | |
321 | ||
322 | ||
79bf2bb3 TG |
323 | #ifdef CONFIG_TICK_ONESHOT |
324 | ||
325 | static cpumask_t tick_broadcast_oneshot_mask; | |
326 | ||
289f480a IM |
327 | /* |
328 | * Debugging: see timer_list.c | |
329 | */ | |
330 | cpumask_t *tick_get_broadcast_oneshot_mask(void) | |
331 | { | |
332 | return &tick_broadcast_oneshot_mask; | |
333 | } | |
334 | ||
79bf2bb3 TG |
335 | static int tick_broadcast_set_event(ktime_t expires, int force) |
336 | { | |
337 | struct clock_event_device *bc = tick_broadcast_device.evtdev; | |
338 | ktime_t now = ktime_get(); | |
339 | int res; | |
340 | ||
341 | for(;;) { | |
342 | res = clockevents_program_event(bc, expires, now); | |
343 | if (!res || !force) | |
344 | return res; | |
345 | now = ktime_get(); | |
346 | expires = ktime_add(now, ktime_set(0, bc->min_delta_ns)); | |
347 | } | |
348 | } | |
349 | ||
350 | /* | |
351 | * Reprogram the broadcast device: | |
352 | * | |
353 | * Called with tick_broadcast_lock held and interrupts disabled. | |
354 | */ | |
355 | static int tick_broadcast_reprogram(void) | |
356 | { | |
357 | ktime_t expires = { .tv64 = KTIME_MAX }; | |
358 | struct tick_device *td; | |
359 | int cpu; | |
360 | ||
361 | /* | |
362 | * Find the event which expires next: | |
363 | */ | |
364 | for (cpu = first_cpu(tick_broadcast_oneshot_mask); cpu != NR_CPUS; | |
365 | cpu = next_cpu(cpu, tick_broadcast_oneshot_mask)) { | |
366 | td = &per_cpu(tick_cpu_device, cpu); | |
367 | if (td->evtdev->next_event.tv64 < expires.tv64) | |
368 | expires = td->evtdev->next_event; | |
369 | } | |
370 | ||
371 | if (expires.tv64 == KTIME_MAX) | |
372 | return 0; | |
373 | ||
374 | return tick_broadcast_set_event(expires, 0); | |
375 | } | |
376 | ||
377 | /* | |
378 | * Handle oneshot mode broadcasting | |
379 | */ | |
380 | static void tick_handle_oneshot_broadcast(struct clock_event_device *dev) | |
381 | { | |
382 | struct tick_device *td; | |
383 | cpumask_t mask; | |
384 | ktime_t now; | |
385 | int cpu; | |
386 | ||
387 | spin_lock(&tick_broadcast_lock); | |
388 | again: | |
389 | dev->next_event.tv64 = KTIME_MAX; | |
390 | mask = CPU_MASK_NONE; | |
391 | now = ktime_get(); | |
392 | /* Find all expired events */ | |
393 | for (cpu = first_cpu(tick_broadcast_oneshot_mask); cpu != NR_CPUS; | |
394 | cpu = next_cpu(cpu, tick_broadcast_oneshot_mask)) { | |
395 | td = &per_cpu(tick_cpu_device, cpu); | |
396 | if (td->evtdev->next_event.tv64 <= now.tv64) | |
397 | cpu_set(cpu, mask); | |
398 | } | |
399 | ||
400 | /* | |
401 | * Wakeup the cpus which have an expired event. The broadcast | |
402 | * device is reprogrammed in the return from idle code. | |
403 | */ | |
404 | if (!tick_do_broadcast(mask)) { | |
405 | /* | |
406 | * The global event did not expire any CPU local | |
407 | * events. This happens in dyntick mode, as the | |
408 | * maximum PIT delta is quite small. | |
409 | */ | |
410 | if (tick_broadcast_reprogram()) | |
411 | goto again; | |
412 | } | |
413 | spin_unlock(&tick_broadcast_lock); | |
414 | } | |
415 | ||
416 | /* | |
417 | * Powerstate information: The system enters/leaves a state, where | |
418 | * affected devices might stop | |
419 | */ | |
420 | void tick_broadcast_oneshot_control(unsigned long reason) | |
421 | { | |
422 | struct clock_event_device *bc, *dev; | |
423 | struct tick_device *td; | |
424 | unsigned long flags; | |
425 | int cpu; | |
426 | ||
427 | spin_lock_irqsave(&tick_broadcast_lock, flags); | |
428 | ||
429 | /* | |
430 | * Periodic mode does not care about the enter/exit of power | |
431 | * states | |
432 | */ | |
433 | if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) | |
434 | goto out; | |
435 | ||
436 | bc = tick_broadcast_device.evtdev; | |
437 | cpu = smp_processor_id(); | |
438 | td = &per_cpu(tick_cpu_device, cpu); | |
439 | dev = td->evtdev; | |
440 | ||
441 | if (!(dev->features & CLOCK_EVT_FEAT_C3STOP)) | |
442 | goto out; | |
443 | ||
444 | if (reason == CLOCK_EVT_NOTIFY_BROADCAST_ENTER) { | |
445 | if (!cpu_isset(cpu, tick_broadcast_oneshot_mask)) { | |
446 | cpu_set(cpu, tick_broadcast_oneshot_mask); | |
447 | clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN); | |
448 | if (dev->next_event.tv64 < bc->next_event.tv64) | |
449 | tick_broadcast_set_event(dev->next_event, 1); | |
450 | } | |
451 | } else { | |
452 | if (cpu_isset(cpu, tick_broadcast_oneshot_mask)) { | |
453 | cpu_clear(cpu, tick_broadcast_oneshot_mask); | |
454 | clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT); | |
455 | if (dev->next_event.tv64 != KTIME_MAX) | |
456 | tick_program_event(dev->next_event, 1); | |
457 | } | |
458 | } | |
459 | ||
460 | out: | |
461 | spin_unlock_irqrestore(&tick_broadcast_lock, flags); | |
462 | } | |
463 | ||
464 | /** | |
465 | * tick_broadcast_setup_highres - setup the broadcast device for highres | |
466 | */ | |
467 | void tick_broadcast_setup_oneshot(struct clock_event_device *bc) | |
468 | { | |
469 | if (bc->mode != CLOCK_EVT_MODE_ONESHOT) { | |
470 | bc->event_handler = tick_handle_oneshot_broadcast; | |
471 | clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT); | |
472 | bc->next_event.tv64 = KTIME_MAX; | |
473 | } | |
474 | } | |
475 | ||
476 | /* | |
477 | * Select oneshot operating mode for the broadcast device | |
478 | */ | |
479 | void tick_broadcast_switch_to_oneshot(void) | |
480 | { | |
481 | struct clock_event_device *bc; | |
482 | unsigned long flags; | |
483 | ||
484 | spin_lock_irqsave(&tick_broadcast_lock, flags); | |
485 | ||
486 | tick_broadcast_device.mode = TICKDEV_MODE_ONESHOT; | |
487 | bc = tick_broadcast_device.evtdev; | |
488 | if (bc) | |
489 | tick_broadcast_setup_oneshot(bc); | |
490 | spin_unlock_irqrestore(&tick_broadcast_lock, flags); | |
491 | } | |
492 | ||
493 | ||
494 | /* | |
495 | * Remove a dead CPU from broadcasting | |
496 | */ | |
497 | void tick_shutdown_broadcast_oneshot(unsigned int *cpup) | |
498 | { | |
499 | struct clock_event_device *bc; | |
500 | unsigned long flags; | |
501 | unsigned int cpu = *cpup; | |
502 | ||
503 | spin_lock_irqsave(&tick_broadcast_lock, flags); | |
504 | ||
505 | bc = tick_broadcast_device.evtdev; | |
506 | cpu_clear(cpu, tick_broadcast_oneshot_mask); | |
507 | ||
508 | if (tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT) { | |
509 | if (bc && cpus_empty(tick_broadcast_oneshot_mask)) | |
510 | clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN); | |
511 | } | |
512 | ||
513 | spin_unlock_irqrestore(&tick_broadcast_lock, flags); | |
514 | } | |
515 | ||
516 | #endif |