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