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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; | |
d3ed7824 | 36 | int tick_do_timer_cpu __read_mostly = -1; |
f8381cba | 37 | DEFINE_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; | |
96 | tick_periodic(cpu); | |
3494c166 | 97 | next = ktime_add(next, tick_period); |
906568c9 TG |
98 | } |
99 | } | |
100 | ||
101 | /* | |
102 | * Setup the device for a periodic tick | |
103 | */ | |
f8381cba | 104 | void tick_setup_periodic(struct clock_event_device *dev, int broadcast) |
906568c9 | 105 | { |
f8381cba TG |
106 | tick_set_periodic_handler(dev, broadcast); |
107 | ||
108 | /* Broadcast setup ? */ | |
109 | if (!tick_device_is_functional(dev)) | |
110 | return; | |
906568c9 TG |
111 | |
112 | if (dev->features & CLOCK_EVT_FEAT_PERIODIC) { | |
113 | clockevents_set_mode(dev, CLOCK_EVT_MODE_PERIODIC); | |
114 | } else { | |
115 | unsigned long seq; | |
116 | ktime_t next; | |
117 | ||
118 | do { | |
119 | seq = read_seqbegin(&xtime_lock); | |
120 | next = tick_next_period; | |
121 | } while (read_seqretry(&xtime_lock, seq)); | |
122 | ||
123 | clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT); | |
124 | ||
125 | for (;;) { | |
126 | if (!clockevents_program_event(dev, next, ktime_get())) | |
127 | return; | |
128 | next = ktime_add(next, tick_period); | |
129 | } | |
130 | } | |
131 | } | |
132 | ||
133 | /* | |
134 | * Setup the tick device | |
135 | */ | |
136 | static void tick_setup_device(struct tick_device *td, | |
137 | struct clock_event_device *newdev, int cpu, | |
c18a41fb | 138 | const cpumask_t *cpumask) |
906568c9 TG |
139 | { |
140 | ktime_t next_event; | |
141 | void (*handler)(struct clock_event_device *) = NULL; | |
142 | ||
143 | /* | |
144 | * First device setup ? | |
145 | */ | |
146 | if (!td->evtdev) { | |
147 | /* | |
148 | * If no cpu took the do_timer update, assign it to | |
149 | * this cpu: | |
150 | */ | |
151 | if (tick_do_timer_cpu == -1) { | |
152 | tick_do_timer_cpu = cpu; | |
153 | tick_next_period = ktime_get(); | |
154 | tick_period = ktime_set(0, NSEC_PER_SEC / HZ); | |
155 | } | |
156 | ||
157 | /* | |
158 | * Startup in periodic mode first. | |
159 | */ | |
160 | td->mode = TICKDEV_MODE_PERIODIC; | |
161 | } else { | |
162 | handler = td->evtdev->event_handler; | |
163 | next_event = td->evtdev->next_event; | |
164 | } | |
165 | ||
166 | td->evtdev = newdev; | |
167 | ||
168 | /* | |
169 | * When the device is not per cpu, pin the interrupt to the | |
170 | * current cpu: | |
171 | */ | |
c18a41fb MT |
172 | if (!cpus_equal(newdev->cpumask, *cpumask)) |
173 | irq_set_affinity(newdev->irq, *cpumask); | |
906568c9 | 174 | |
f8381cba TG |
175 | /* |
176 | * When global broadcasting is active, check if the current | |
177 | * device is registered as a placeholder for broadcast mode. | |
178 | * This allows us to handle this x86 misfeature in a generic | |
179 | * way. | |
180 | */ | |
181 | if (tick_device_uses_broadcast(newdev, cpu)) | |
182 | return; | |
183 | ||
906568c9 TG |
184 | if (td->mode == TICKDEV_MODE_PERIODIC) |
185 | tick_setup_periodic(newdev, 0); | |
79bf2bb3 TG |
186 | else |
187 | tick_setup_oneshot(newdev, handler, next_event); | |
906568c9 TG |
188 | } |
189 | ||
190 | /* | |
191 | * Check, if the new registered device should be used. | |
192 | */ | |
193 | static int tick_check_new_device(struct clock_event_device *newdev) | |
194 | { | |
195 | struct clock_event_device *curdev; | |
196 | struct tick_device *td; | |
197 | int cpu, ret = NOTIFY_OK; | |
198 | unsigned long flags; | |
c18a41fb | 199 | cpumask_of_cpu_ptr_declare(cpumask); |
906568c9 TG |
200 | |
201 | spin_lock_irqsave(&tick_device_lock, flags); | |
202 | ||
203 | cpu = smp_processor_id(); | |
c18a41fb | 204 | cpumask_of_cpu_ptr_next(cpumask, cpu); |
906568c9 | 205 | if (!cpu_isset(cpu, newdev->cpumask)) |
4a93232d | 206 | goto out_bc; |
906568c9 TG |
207 | |
208 | td = &per_cpu(tick_cpu_device, cpu); | |
209 | curdev = td->evtdev; | |
906568c9 TG |
210 | |
211 | /* cpu local device ? */ | |
c18a41fb | 212 | if (!cpus_equal(newdev->cpumask, *cpumask)) { |
906568c9 TG |
213 | |
214 | /* | |
215 | * If the cpu affinity of the device interrupt can not | |
216 | * be set, ignore it. | |
217 | */ | |
218 | if (!irq_can_set_affinity(newdev->irq)) | |
219 | goto out_bc; | |
220 | ||
221 | /* | |
222 | * If we have a cpu local device already, do not replace it | |
223 | * by a non cpu local device | |
224 | */ | |
c18a41fb | 225 | if (curdev && cpus_equal(curdev->cpumask, *cpumask)) |
906568c9 TG |
226 | goto out_bc; |
227 | } | |
228 | ||
229 | /* | |
230 | * If we have an active device, then check the rating and the oneshot | |
231 | * feature. | |
232 | */ | |
233 | if (curdev) { | |
79bf2bb3 TG |
234 | /* |
235 | * Prefer one shot capable devices ! | |
236 | */ | |
237 | if ((curdev->features & CLOCK_EVT_FEAT_ONESHOT) && | |
238 | !(newdev->features & CLOCK_EVT_FEAT_ONESHOT)) | |
239 | goto out_bc; | |
906568c9 TG |
240 | /* |
241 | * Check the rating | |
242 | */ | |
243 | if (curdev->rating >= newdev->rating) | |
f8381cba | 244 | goto out_bc; |
906568c9 TG |
245 | } |
246 | ||
247 | /* | |
248 | * Replace the eventually existing device by the new | |
f8381cba TG |
249 | * device. If the current device is the broadcast device, do |
250 | * not give it back to the clockevents layer ! | |
906568c9 | 251 | */ |
f8381cba TG |
252 | if (tick_is_broadcast_device(curdev)) { |
253 | clockevents_set_mode(curdev, CLOCK_EVT_MODE_SHUTDOWN); | |
254 | curdev = NULL; | |
255 | } | |
906568c9 TG |
256 | clockevents_exchange_device(curdev, newdev); |
257 | tick_setup_device(td, newdev, cpu, cpumask); | |
79bf2bb3 TG |
258 | if (newdev->features & CLOCK_EVT_FEAT_ONESHOT) |
259 | tick_oneshot_notify(); | |
906568c9 | 260 | |
f8381cba TG |
261 | spin_unlock_irqrestore(&tick_device_lock, flags); |
262 | return NOTIFY_STOP; | |
263 | ||
264 | out_bc: | |
265 | /* | |
266 | * Can the new device be used as a broadcast device ? | |
267 | */ | |
268 | if (tick_check_broadcast_device(newdev)) | |
269 | ret = NOTIFY_STOP; | |
4a93232d | 270 | |
906568c9 | 271 | spin_unlock_irqrestore(&tick_device_lock, flags); |
f8381cba | 272 | |
906568c9 TG |
273 | return ret; |
274 | } | |
275 | ||
276 | /* | |
277 | * Shutdown an event device on a given cpu: | |
278 | * | |
279 | * This is called on a life CPU, when a CPU is dead. So we cannot | |
280 | * access the hardware device itself. | |
281 | * We just set the mode and remove it from the lists. | |
282 | */ | |
283 | static void tick_shutdown(unsigned int *cpup) | |
284 | { | |
285 | struct tick_device *td = &per_cpu(tick_cpu_device, *cpup); | |
286 | struct clock_event_device *dev = td->evtdev; | |
287 | unsigned long flags; | |
288 | ||
289 | spin_lock_irqsave(&tick_device_lock, flags); | |
290 | td->mode = TICKDEV_MODE_PERIODIC; | |
291 | if (dev) { | |
292 | /* | |
293 | * Prevent that the clock events layer tries to call | |
294 | * the set mode function! | |
295 | */ | |
296 | dev->mode = CLOCK_EVT_MODE_UNUSED; | |
297 | clockevents_exchange_device(dev, NULL); | |
298 | td->evtdev = NULL; | |
299 | } | |
d3ed7824 TG |
300 | /* Transfer the do_timer job away from this cpu */ |
301 | if (*cpup == tick_do_timer_cpu) { | |
302 | int cpu = first_cpu(cpu_online_map); | |
303 | ||
304 | tick_do_timer_cpu = (cpu != NR_CPUS) ? cpu : -1; | |
305 | } | |
906568c9 TG |
306 | spin_unlock_irqrestore(&tick_device_lock, flags); |
307 | } | |
308 | ||
cd05a1f8 | 309 | static void tick_suspend(void) |
6321dd60 TG |
310 | { |
311 | struct tick_device *td = &__get_cpu_var(tick_cpu_device); | |
312 | unsigned long flags; | |
313 | ||
314 | spin_lock_irqsave(&tick_device_lock, flags); | |
cd05a1f8 | 315 | clockevents_set_mode(td->evtdev, CLOCK_EVT_MODE_SHUTDOWN); |
6321dd60 TG |
316 | spin_unlock_irqrestore(&tick_device_lock, flags); |
317 | } | |
318 | ||
cd05a1f8 | 319 | static void tick_resume(void) |
6321dd60 TG |
320 | { |
321 | struct tick_device *td = &__get_cpu_var(tick_cpu_device); | |
322 | unsigned long flags; | |
18de5bc4 | 323 | int broadcast = tick_resume_broadcast(); |
6321dd60 TG |
324 | |
325 | spin_lock_irqsave(&tick_device_lock, flags); | |
18de5bc4 TG |
326 | clockevents_set_mode(td->evtdev, CLOCK_EVT_MODE_RESUME); |
327 | ||
328 | if (!broadcast) { | |
329 | if (td->mode == TICKDEV_MODE_PERIODIC) | |
330 | tick_setup_periodic(td->evtdev, 0); | |
331 | else | |
332 | tick_resume_oneshot(); | |
333 | } | |
6321dd60 TG |
334 | spin_unlock_irqrestore(&tick_device_lock, flags); |
335 | } | |
336 | ||
906568c9 TG |
337 | /* |
338 | * Notification about clock event devices | |
339 | */ | |
340 | static int tick_notify(struct notifier_block *nb, unsigned long reason, | |
341 | void *dev) | |
342 | { | |
343 | switch (reason) { | |
344 | ||
345 | case CLOCK_EVT_NOTIFY_ADD: | |
346 | return tick_check_new_device(dev); | |
347 | ||
f8381cba TG |
348 | case CLOCK_EVT_NOTIFY_BROADCAST_ON: |
349 | case CLOCK_EVT_NOTIFY_BROADCAST_OFF: | |
1595f452 | 350 | case CLOCK_EVT_NOTIFY_BROADCAST_FORCE: |
f8381cba TG |
351 | tick_broadcast_on_off(reason, dev); |
352 | break; | |
353 | ||
79bf2bb3 TG |
354 | case CLOCK_EVT_NOTIFY_BROADCAST_ENTER: |
355 | case CLOCK_EVT_NOTIFY_BROADCAST_EXIT: | |
356 | tick_broadcast_oneshot_control(reason); | |
357 | break; | |
358 | ||
906568c9 | 359 | case CLOCK_EVT_NOTIFY_CPU_DEAD: |
79bf2bb3 | 360 | tick_shutdown_broadcast_oneshot(dev); |
f8381cba | 361 | tick_shutdown_broadcast(dev); |
906568c9 TG |
362 | tick_shutdown(dev); |
363 | break; | |
364 | ||
6321dd60 | 365 | case CLOCK_EVT_NOTIFY_SUSPEND: |
cd05a1f8 | 366 | tick_suspend(); |
6321dd60 TG |
367 | tick_suspend_broadcast(); |
368 | break; | |
369 | ||
370 | case CLOCK_EVT_NOTIFY_RESUME: | |
18de5bc4 | 371 | tick_resume(); |
6321dd60 TG |
372 | break; |
373 | ||
906568c9 TG |
374 | default: |
375 | break; | |
376 | } | |
377 | ||
378 | return NOTIFY_OK; | |
379 | } | |
380 | ||
381 | static struct notifier_block tick_notifier = { | |
382 | .notifier_call = tick_notify, | |
383 | }; | |
384 | ||
385 | /** | |
386 | * tick_init - initialize the tick control | |
387 | * | |
388 | * Register the notifier with the clockevents framework | |
389 | */ | |
390 | void __init tick_init(void) | |
391 | { | |
392 | clockevents_register_notifier(&tick_notifier); | |
393 | } |