Commit | Line | Data |
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906568c9 TG |
1 | /* |
2 | * linux/kernel/time/tick-common.c | |
3 | * | |
4 | * This file contains the base functions to manage periodic tick | |
5 | * related events. | |
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> | |
d7b90689 | 17 | #include <linux/interrupt.h> |
906568c9 TG |
18 | #include <linux/percpu.h> |
19 | #include <linux/profile.h> | |
20 | #include <linux/sched.h> | |
906568c9 | 21 | |
d7b90689 RK |
22 | #include <asm/irq_regs.h> |
23 | ||
f8381cba TG |
24 | #include "tick-internal.h" |
25 | ||
906568c9 TG |
26 | /* |
27 | * Tick devices | |
28 | */ | |
f8381cba | 29 | DEFINE_PER_CPU(struct tick_device, tick_cpu_device); |
906568c9 TG |
30 | /* |
31 | * Tick next event: keeps track of the tick time | |
32 | */ | |
f8381cba TG |
33 | ktime_t tick_next_period; |
34 | ktime_t tick_period; | |
6441402b | 35 | int tick_do_timer_cpu __read_mostly = TICK_DO_TIMER_BOOT; |
b5f91da0 | 36 | static DEFINE_RAW_SPINLOCK(tick_device_lock); |
906568c9 | 37 | |
289f480a IM |
38 | /* |
39 | * Debugging: see timer_list.c | |
40 | */ | |
41 | struct tick_device *tick_get_device(int cpu) | |
42 | { | |
43 | return &per_cpu(tick_cpu_device, cpu); | |
44 | } | |
45 | ||
79bf2bb3 TG |
46 | /** |
47 | * tick_is_oneshot_available - check for a oneshot capable event device | |
48 | */ | |
49 | int tick_is_oneshot_available(void) | |
50 | { | |
909ea964 | 51 | struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev); |
79bf2bb3 | 52 | |
3a142a06 TG |
53 | if (!dev || !(dev->features & CLOCK_EVT_FEAT_ONESHOT)) |
54 | return 0; | |
55 | if (!(dev->features & CLOCK_EVT_FEAT_C3STOP)) | |
56 | return 1; | |
57 | return tick_broadcast_oneshot_available(); | |
79bf2bb3 TG |
58 | } |
59 | ||
906568c9 TG |
60 | /* |
61 | * Periodic tick | |
62 | */ | |
63 | static void tick_periodic(int cpu) | |
64 | { | |
65 | if (tick_do_timer_cpu == cpu) { | |
66 | write_seqlock(&xtime_lock); | |
67 | ||
68 | /* Keep track of the next tick event */ | |
69 | tick_next_period = ktime_add(tick_next_period, tick_period); | |
70 | ||
71 | do_timer(1); | |
72 | write_sequnlock(&xtime_lock); | |
73 | } | |
74 | ||
75 | update_process_times(user_mode(get_irq_regs())); | |
76 | profile_tick(CPU_PROFILING); | |
77 | } | |
78 | ||
79 | /* | |
80 | * Event handler for periodic ticks | |
81 | */ | |
82 | void tick_handle_periodic(struct clock_event_device *dev) | |
83 | { | |
84 | int cpu = smp_processor_id(); | |
3494c166 | 85 | ktime_t next; |
906568c9 TG |
86 | |
87 | tick_periodic(cpu); | |
88 | ||
89 | if (dev->mode != CLOCK_EVT_MODE_ONESHOT) | |
90 | return; | |
91 | /* | |
92 | * Setup the next period for devices, which do not have | |
93 | * periodic mode: | |
94 | */ | |
3494c166 | 95 | next = ktime_add(dev->next_event, tick_period); |
906568c9 | 96 | for (;;) { |
d1748302 | 97 | if (!clockevents_program_event(dev, next, false)) |
906568c9 | 98 | return; |
74a03b69 | 99 | /* |
100 | * Have to be careful here. If we're in oneshot mode, | |
101 | * before we call tick_periodic() in a loop, we need | |
102 | * to be sure we're using a real hardware clocksource. | |
103 | * Otherwise we could get trapped in an infinite | |
104 | * loop, as the tick_periodic() increments jiffies, | |
105 | * when then will increment time, posibly causing | |
106 | * the loop to trigger again and again. | |
107 | */ | |
108 | if (timekeeping_valid_for_hres()) | |
109 | tick_periodic(cpu); | |
3494c166 | 110 | next = ktime_add(next, tick_period); |
906568c9 TG |
111 | } |
112 | } | |
113 | ||
114 | /* | |
115 | * Setup the device for a periodic tick | |
116 | */ | |
f8381cba | 117 | void tick_setup_periodic(struct clock_event_device *dev, int broadcast) |
906568c9 | 118 | { |
f8381cba TG |
119 | tick_set_periodic_handler(dev, broadcast); |
120 | ||
121 | /* Broadcast setup ? */ | |
122 | if (!tick_device_is_functional(dev)) | |
123 | return; | |
906568c9 | 124 | |
27ce4cb4 TG |
125 | if ((dev->features & CLOCK_EVT_FEAT_PERIODIC) && |
126 | !tick_broadcast_oneshot_active()) { | |
906568c9 TG |
127 | clockevents_set_mode(dev, CLOCK_EVT_MODE_PERIODIC); |
128 | } else { | |
129 | unsigned long seq; | |
130 | ktime_t next; | |
131 | ||
132 | do { | |
133 | seq = read_seqbegin(&xtime_lock); | |
134 | next = tick_next_period; | |
135 | } while (read_seqretry(&xtime_lock, seq)); | |
136 | ||
137 | clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT); | |
138 | ||
139 | for (;;) { | |
d1748302 | 140 | if (!clockevents_program_event(dev, next, false)) |
906568c9 TG |
141 | return; |
142 | next = ktime_add(next, tick_period); | |
143 | } | |
144 | } | |
145 | } | |
146 | ||
147 | /* | |
148 | * Setup the tick device | |
149 | */ | |
150 | static void tick_setup_device(struct tick_device *td, | |
151 | struct clock_event_device *newdev, int cpu, | |
0de26520 | 152 | const struct cpumask *cpumask) |
906568c9 TG |
153 | { |
154 | ktime_t next_event; | |
155 | void (*handler)(struct clock_event_device *) = NULL; | |
156 | ||
157 | /* | |
158 | * First device setup ? | |
159 | */ | |
160 | if (!td->evtdev) { | |
161 | /* | |
162 | * If no cpu took the do_timer update, assign it to | |
163 | * this cpu: | |
164 | */ | |
6441402b | 165 | if (tick_do_timer_cpu == TICK_DO_TIMER_BOOT) { |
906568c9 TG |
166 | tick_do_timer_cpu = cpu; |
167 | tick_next_period = ktime_get(); | |
168 | tick_period = ktime_set(0, NSEC_PER_SEC / HZ); | |
169 | } | |
170 | ||
171 | /* | |
172 | * Startup in periodic mode first. | |
173 | */ | |
174 | td->mode = TICKDEV_MODE_PERIODIC; | |
175 | } else { | |
176 | handler = td->evtdev->event_handler; | |
177 | next_event = td->evtdev->next_event; | |
7c1e7689 | 178 | td->evtdev->event_handler = clockevents_handle_noop; |
906568c9 TG |
179 | } |
180 | ||
181 | td->evtdev = newdev; | |
182 | ||
183 | /* | |
184 | * When the device is not per cpu, pin the interrupt to the | |
185 | * current cpu: | |
186 | */ | |
320ab2b0 | 187 | if (!cpumask_equal(newdev->cpumask, cpumask)) |
0de26520 | 188 | irq_set_affinity(newdev->irq, cpumask); |
906568c9 | 189 | |
f8381cba TG |
190 | /* |
191 | * When global broadcasting is active, check if the current | |
192 | * device is registered as a placeholder for broadcast mode. | |
193 | * This allows us to handle this x86 misfeature in a generic | |
194 | * way. | |
195 | */ | |
196 | if (tick_device_uses_broadcast(newdev, cpu)) | |
197 | return; | |
198 | ||
906568c9 TG |
199 | if (td->mode == TICKDEV_MODE_PERIODIC) |
200 | tick_setup_periodic(newdev, 0); | |
79bf2bb3 TG |
201 | else |
202 | tick_setup_oneshot(newdev, handler, next_event); | |
906568c9 TG |
203 | } |
204 | ||
205 | /* | |
206 | * Check, if the new registered device should be used. | |
207 | */ | |
208 | static int tick_check_new_device(struct clock_event_device *newdev) | |
209 | { | |
210 | struct clock_event_device *curdev; | |
211 | struct tick_device *td; | |
212 | int cpu, ret = NOTIFY_OK; | |
213 | unsigned long flags; | |
906568c9 | 214 | |
b5f91da0 | 215 | raw_spin_lock_irqsave(&tick_device_lock, flags); |
906568c9 TG |
216 | |
217 | cpu = smp_processor_id(); | |
320ab2b0 | 218 | if (!cpumask_test_cpu(cpu, newdev->cpumask)) |
4a93232d | 219 | goto out_bc; |
906568c9 TG |
220 | |
221 | td = &per_cpu(tick_cpu_device, cpu); | |
222 | curdev = td->evtdev; | |
906568c9 TG |
223 | |
224 | /* cpu local device ? */ | |
320ab2b0 | 225 | if (!cpumask_equal(newdev->cpumask, cpumask_of(cpu))) { |
906568c9 TG |
226 | |
227 | /* | |
228 | * If the cpu affinity of the device interrupt can not | |
229 | * be set, ignore it. | |
230 | */ | |
231 | if (!irq_can_set_affinity(newdev->irq)) | |
232 | goto out_bc; | |
233 | ||
234 | /* | |
235 | * If we have a cpu local device already, do not replace it | |
236 | * by a non cpu local device | |
237 | */ | |
320ab2b0 | 238 | if (curdev && cpumask_equal(curdev->cpumask, cpumask_of(cpu))) |
906568c9 TG |
239 | goto out_bc; |
240 | } | |
241 | ||
242 | /* | |
243 | * If we have an active device, then check the rating and the oneshot | |
244 | * feature. | |
245 | */ | |
246 | if (curdev) { | |
79bf2bb3 TG |
247 | /* |
248 | * Prefer one shot capable devices ! | |
249 | */ | |
250 | if ((curdev->features & CLOCK_EVT_FEAT_ONESHOT) && | |
251 | !(newdev->features & CLOCK_EVT_FEAT_ONESHOT)) | |
252 | goto out_bc; | |
906568c9 TG |
253 | /* |
254 | * Check the rating | |
255 | */ | |
256 | if (curdev->rating >= newdev->rating) | |
f8381cba | 257 | goto out_bc; |
906568c9 TG |
258 | } |
259 | ||
260 | /* | |
261 | * Replace the eventually existing device by the new | |
f8381cba TG |
262 | * device. If the current device is the broadcast device, do |
263 | * not give it back to the clockevents layer ! | |
906568c9 | 264 | */ |
f8381cba | 265 | if (tick_is_broadcast_device(curdev)) { |
2344abbc | 266 | clockevents_shutdown(curdev); |
f8381cba TG |
267 | curdev = NULL; |
268 | } | |
906568c9 | 269 | clockevents_exchange_device(curdev, newdev); |
6b954823 | 270 | tick_setup_device(td, newdev, cpu, cpumask_of(cpu)); |
79bf2bb3 TG |
271 | if (newdev->features & CLOCK_EVT_FEAT_ONESHOT) |
272 | tick_oneshot_notify(); | |
906568c9 | 273 | |
b5f91da0 | 274 | raw_spin_unlock_irqrestore(&tick_device_lock, flags); |
f8381cba TG |
275 | return NOTIFY_STOP; |
276 | ||
277 | out_bc: | |
278 | /* | |
279 | * Can the new device be used as a broadcast device ? | |
280 | */ | |
281 | if (tick_check_broadcast_device(newdev)) | |
282 | ret = NOTIFY_STOP; | |
4a93232d | 283 | |
b5f91da0 | 284 | raw_spin_unlock_irqrestore(&tick_device_lock, flags); |
f8381cba | 285 | |
906568c9 TG |
286 | return ret; |
287 | } | |
288 | ||
94df7de0 SD |
289 | /* |
290 | * Transfer the do_timer job away from a dying cpu. | |
291 | * | |
292 | * Called with interrupts disabled. | |
293 | */ | |
294 | static void tick_handover_do_timer(int *cpup) | |
295 | { | |
296 | if (*cpup == tick_do_timer_cpu) { | |
297 | int cpu = cpumask_first(cpu_online_mask); | |
298 | ||
299 | tick_do_timer_cpu = (cpu < nr_cpu_ids) ? cpu : | |
300 | TICK_DO_TIMER_NONE; | |
301 | } | |
302 | } | |
303 | ||
906568c9 TG |
304 | /* |
305 | * Shutdown an event device on a given cpu: | |
306 | * | |
307 | * This is called on a life CPU, when a CPU is dead. So we cannot | |
308 | * access the hardware device itself. | |
309 | * We just set the mode and remove it from the lists. | |
310 | */ | |
311 | static void tick_shutdown(unsigned int *cpup) | |
312 | { | |
313 | struct tick_device *td = &per_cpu(tick_cpu_device, *cpup); | |
314 | struct clock_event_device *dev = td->evtdev; | |
315 | unsigned long flags; | |
316 | ||
b5f91da0 | 317 | raw_spin_lock_irqsave(&tick_device_lock, flags); |
906568c9 TG |
318 | td->mode = TICKDEV_MODE_PERIODIC; |
319 | if (dev) { | |
320 | /* | |
321 | * Prevent that the clock events layer tries to call | |
322 | * the set mode function! | |
323 | */ | |
324 | dev->mode = CLOCK_EVT_MODE_UNUSED; | |
325 | clockevents_exchange_device(dev, NULL); | |
326 | td->evtdev = NULL; | |
327 | } | |
b5f91da0 | 328 | raw_spin_unlock_irqrestore(&tick_device_lock, flags); |
906568c9 TG |
329 | } |
330 | ||
cd05a1f8 | 331 | static void tick_suspend(void) |
6321dd60 TG |
332 | { |
333 | struct tick_device *td = &__get_cpu_var(tick_cpu_device); | |
334 | unsigned long flags; | |
335 | ||
b5f91da0 | 336 | raw_spin_lock_irqsave(&tick_device_lock, flags); |
2344abbc | 337 | clockevents_shutdown(td->evtdev); |
b5f91da0 | 338 | raw_spin_unlock_irqrestore(&tick_device_lock, flags); |
6321dd60 TG |
339 | } |
340 | ||
cd05a1f8 | 341 | static void tick_resume(void) |
6321dd60 TG |
342 | { |
343 | struct tick_device *td = &__get_cpu_var(tick_cpu_device); | |
344 | unsigned long flags; | |
18de5bc4 | 345 | int broadcast = tick_resume_broadcast(); |
6321dd60 | 346 | |
b5f91da0 | 347 | raw_spin_lock_irqsave(&tick_device_lock, flags); |
18de5bc4 TG |
348 | clockevents_set_mode(td->evtdev, CLOCK_EVT_MODE_RESUME); |
349 | ||
350 | if (!broadcast) { | |
351 | if (td->mode == TICKDEV_MODE_PERIODIC) | |
352 | tick_setup_periodic(td->evtdev, 0); | |
353 | else | |
354 | tick_resume_oneshot(); | |
355 | } | |
b5f91da0 | 356 | raw_spin_unlock_irqrestore(&tick_device_lock, flags); |
6321dd60 TG |
357 | } |
358 | ||
906568c9 TG |
359 | /* |
360 | * Notification about clock event devices | |
361 | */ | |
362 | static int tick_notify(struct notifier_block *nb, unsigned long reason, | |
363 | void *dev) | |
364 | { | |
365 | switch (reason) { | |
366 | ||
367 | case CLOCK_EVT_NOTIFY_ADD: | |
368 | return tick_check_new_device(dev); | |
369 | ||
f8381cba TG |
370 | case CLOCK_EVT_NOTIFY_BROADCAST_ON: |
371 | case CLOCK_EVT_NOTIFY_BROADCAST_OFF: | |
1595f452 | 372 | case CLOCK_EVT_NOTIFY_BROADCAST_FORCE: |
f8381cba TG |
373 | tick_broadcast_on_off(reason, dev); |
374 | break; | |
375 | ||
79bf2bb3 TG |
376 | case CLOCK_EVT_NOTIFY_BROADCAST_ENTER: |
377 | case CLOCK_EVT_NOTIFY_BROADCAST_EXIT: | |
378 | tick_broadcast_oneshot_control(reason); | |
379 | break; | |
380 | ||
94df7de0 SD |
381 | case CLOCK_EVT_NOTIFY_CPU_DYING: |
382 | tick_handover_do_timer(dev); | |
383 | break; | |
384 | ||
906568c9 | 385 | case CLOCK_EVT_NOTIFY_CPU_DEAD: |
79bf2bb3 | 386 | tick_shutdown_broadcast_oneshot(dev); |
f8381cba | 387 | tick_shutdown_broadcast(dev); |
906568c9 TG |
388 | tick_shutdown(dev); |
389 | break; | |
390 | ||
6321dd60 | 391 | case CLOCK_EVT_NOTIFY_SUSPEND: |
cd05a1f8 | 392 | tick_suspend(); |
6321dd60 TG |
393 | tick_suspend_broadcast(); |
394 | break; | |
395 | ||
396 | case CLOCK_EVT_NOTIFY_RESUME: | |
18de5bc4 | 397 | tick_resume(); |
6321dd60 TG |
398 | break; |
399 | ||
906568c9 TG |
400 | default: |
401 | break; | |
402 | } | |
403 | ||
404 | return NOTIFY_OK; | |
405 | } | |
406 | ||
407 | static struct notifier_block tick_notifier = { | |
408 | .notifier_call = tick_notify, | |
409 | }; | |
410 | ||
411 | /** | |
412 | * tick_init - initialize the tick control | |
413 | * | |
414 | * Register the notifier with the clockevents framework | |
415 | */ | |
416 | void __init tick_init(void) | |
417 | { | |
418 | clockevents_register_notifier(&tick_notifier); | |
419 | } |