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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; | |
7c1e7689 | 164 | td->evtdev->event_handler = clockevents_handle_noop; |
906568c9 TG |
165 | } |
166 | ||
167 | td->evtdev = newdev; | |
168 | ||
169 | /* | |
170 | * When the device is not per cpu, pin the interrupt to the | |
171 | * current cpu: | |
172 | */ | |
c18a41fb MT |
173 | if (!cpus_equal(newdev->cpumask, *cpumask)) |
174 | irq_set_affinity(newdev->irq, *cpumask); | |
906568c9 | 175 | |
f8381cba TG |
176 | /* |
177 | * When global broadcasting is active, check if the current | |
178 | * device is registered as a placeholder for broadcast mode. | |
179 | * This allows us to handle this x86 misfeature in a generic | |
180 | * way. | |
181 | */ | |
182 | if (tick_device_uses_broadcast(newdev, cpu)) | |
183 | return; | |
184 | ||
906568c9 TG |
185 | if (td->mode == TICKDEV_MODE_PERIODIC) |
186 | tick_setup_periodic(newdev, 0); | |
79bf2bb3 TG |
187 | else |
188 | tick_setup_oneshot(newdev, handler, next_event); | |
906568c9 TG |
189 | } |
190 | ||
191 | /* | |
192 | * Check, if the new registered device should be used. | |
193 | */ | |
194 | static int tick_check_new_device(struct clock_event_device *newdev) | |
195 | { | |
196 | struct clock_event_device *curdev; | |
197 | struct tick_device *td; | |
198 | int cpu, ret = NOTIFY_OK; | |
199 | unsigned long flags; | |
906568c9 TG |
200 | |
201 | spin_lock_irqsave(&tick_device_lock, flags); | |
202 | ||
203 | cpu = smp_processor_id(); | |
204 | if (!cpu_isset(cpu, newdev->cpumask)) | |
4a93232d | 205 | goto out_bc; |
906568c9 TG |
206 | |
207 | td = &per_cpu(tick_cpu_device, cpu); | |
208 | curdev = td->evtdev; | |
906568c9 TG |
209 | |
210 | /* cpu local device ? */ | |
0bc3cc03 | 211 | if (!cpus_equal(newdev->cpumask, cpumask_of_cpu(cpu))) { |
906568c9 TG |
212 | |
213 | /* | |
214 | * If the cpu affinity of the device interrupt can not | |
215 | * be set, ignore it. | |
216 | */ | |
217 | if (!irq_can_set_affinity(newdev->irq)) | |
218 | goto out_bc; | |
219 | ||
220 | /* | |
221 | * If we have a cpu local device already, do not replace it | |
222 | * by a non cpu local device | |
223 | */ | |
0bc3cc03 | 224 | if (curdev && cpus_equal(curdev->cpumask, cpumask_of_cpu(cpu))) |
906568c9 TG |
225 | goto out_bc; |
226 | } | |
227 | ||
228 | /* | |
229 | * If we have an active device, then check the rating and the oneshot | |
230 | * feature. | |
231 | */ | |
232 | if (curdev) { | |
79bf2bb3 TG |
233 | /* |
234 | * Prefer one shot capable devices ! | |
235 | */ | |
236 | if ((curdev->features & CLOCK_EVT_FEAT_ONESHOT) && | |
237 | !(newdev->features & CLOCK_EVT_FEAT_ONESHOT)) | |
238 | goto out_bc; | |
906568c9 TG |
239 | /* |
240 | * Check the rating | |
241 | */ | |
242 | if (curdev->rating >= newdev->rating) | |
f8381cba | 243 | goto out_bc; |
906568c9 TG |
244 | } |
245 | ||
246 | /* | |
247 | * Replace the eventually existing device by the new | |
f8381cba TG |
248 | * device. If the current device is the broadcast device, do |
249 | * not give it back to the clockevents layer ! | |
906568c9 | 250 | */ |
f8381cba | 251 | if (tick_is_broadcast_device(curdev)) { |
2344abbc | 252 | clockevents_shutdown(curdev); |
f8381cba TG |
253 | curdev = NULL; |
254 | } | |
906568c9 | 255 | clockevents_exchange_device(curdev, newdev); |
0bc3cc03 | 256 | tick_setup_device(td, newdev, cpu, &cpumask_of_cpu(cpu)); |
79bf2bb3 TG |
257 | if (newdev->features & CLOCK_EVT_FEAT_ONESHOT) |
258 | tick_oneshot_notify(); | |
906568c9 | 259 | |
f8381cba TG |
260 | spin_unlock_irqrestore(&tick_device_lock, flags); |
261 | return NOTIFY_STOP; | |
262 | ||
263 | out_bc: | |
264 | /* | |
265 | * Can the new device be used as a broadcast device ? | |
266 | */ | |
267 | if (tick_check_broadcast_device(newdev)) | |
268 | ret = NOTIFY_STOP; | |
4a93232d | 269 | |
906568c9 | 270 | spin_unlock_irqrestore(&tick_device_lock, flags); |
f8381cba | 271 | |
906568c9 TG |
272 | return ret; |
273 | } | |
274 | ||
275 | /* | |
276 | * Shutdown an event device on a given cpu: | |
277 | * | |
278 | * This is called on a life CPU, when a CPU is dead. So we cannot | |
279 | * access the hardware device itself. | |
280 | * We just set the mode and remove it from the lists. | |
281 | */ | |
282 | static void tick_shutdown(unsigned int *cpup) | |
283 | { | |
284 | struct tick_device *td = &per_cpu(tick_cpu_device, *cpup); | |
285 | struct clock_event_device *dev = td->evtdev; | |
286 | unsigned long flags; | |
287 | ||
288 | spin_lock_irqsave(&tick_device_lock, flags); | |
289 | td->mode = TICKDEV_MODE_PERIODIC; | |
290 | if (dev) { | |
291 | /* | |
292 | * Prevent that the clock events layer tries to call | |
293 | * the set mode function! | |
294 | */ | |
295 | dev->mode = CLOCK_EVT_MODE_UNUSED; | |
296 | clockevents_exchange_device(dev, NULL); | |
297 | td->evtdev = NULL; | |
298 | } | |
d3ed7824 TG |
299 | /* Transfer the do_timer job away from this cpu */ |
300 | if (*cpup == tick_do_timer_cpu) { | |
301 | int cpu = first_cpu(cpu_online_map); | |
302 | ||
303 | tick_do_timer_cpu = (cpu != NR_CPUS) ? cpu : -1; | |
304 | } | |
906568c9 TG |
305 | spin_unlock_irqrestore(&tick_device_lock, flags); |
306 | } | |
307 | ||
cd05a1f8 | 308 | static void tick_suspend(void) |
6321dd60 TG |
309 | { |
310 | struct tick_device *td = &__get_cpu_var(tick_cpu_device); | |
311 | unsigned long flags; | |
312 | ||
313 | spin_lock_irqsave(&tick_device_lock, flags); | |
2344abbc | 314 | clockevents_shutdown(td->evtdev); |
6321dd60 TG |
315 | spin_unlock_irqrestore(&tick_device_lock, flags); |
316 | } | |
317 | ||
cd05a1f8 | 318 | static void tick_resume(void) |
6321dd60 TG |
319 | { |
320 | struct tick_device *td = &__get_cpu_var(tick_cpu_device); | |
321 | unsigned long flags; | |
18de5bc4 | 322 | int broadcast = tick_resume_broadcast(); |
6321dd60 TG |
323 | |
324 | spin_lock_irqsave(&tick_device_lock, flags); | |
18de5bc4 TG |
325 | clockevents_set_mode(td->evtdev, CLOCK_EVT_MODE_RESUME); |
326 | ||
327 | if (!broadcast) { | |
328 | if (td->mode == TICKDEV_MODE_PERIODIC) | |
329 | tick_setup_periodic(td->evtdev, 0); | |
330 | else | |
331 | tick_resume_oneshot(); | |
332 | } | |
6321dd60 TG |
333 | spin_unlock_irqrestore(&tick_device_lock, flags); |
334 | } | |
335 | ||
906568c9 TG |
336 | /* |
337 | * Notification about clock event devices | |
338 | */ | |
339 | static int tick_notify(struct notifier_block *nb, unsigned long reason, | |
340 | void *dev) | |
341 | { | |
342 | switch (reason) { | |
343 | ||
344 | case CLOCK_EVT_NOTIFY_ADD: | |
345 | return tick_check_new_device(dev); | |
346 | ||
f8381cba TG |
347 | case CLOCK_EVT_NOTIFY_BROADCAST_ON: |
348 | case CLOCK_EVT_NOTIFY_BROADCAST_OFF: | |
1595f452 | 349 | case CLOCK_EVT_NOTIFY_BROADCAST_FORCE: |
f8381cba TG |
350 | tick_broadcast_on_off(reason, dev); |
351 | break; | |
352 | ||
79bf2bb3 TG |
353 | case CLOCK_EVT_NOTIFY_BROADCAST_ENTER: |
354 | case CLOCK_EVT_NOTIFY_BROADCAST_EXIT: | |
355 | tick_broadcast_oneshot_control(reason); | |
356 | break; | |
357 | ||
906568c9 | 358 | case CLOCK_EVT_NOTIFY_CPU_DEAD: |
79bf2bb3 | 359 | tick_shutdown_broadcast_oneshot(dev); |
f8381cba | 360 | tick_shutdown_broadcast(dev); |
906568c9 TG |
361 | tick_shutdown(dev); |
362 | break; | |
363 | ||
6321dd60 | 364 | case CLOCK_EVT_NOTIFY_SUSPEND: |
cd05a1f8 | 365 | tick_suspend(); |
6321dd60 TG |
366 | tick_suspend_broadcast(); |
367 | break; | |
368 | ||
369 | case CLOCK_EVT_NOTIFY_RESUME: | |
18de5bc4 | 370 | tick_resume(); |
6321dd60 TG |
371 | break; |
372 | ||
906568c9 TG |
373 | default: |
374 | break; | |
375 | } | |
376 | ||
377 | return NOTIFY_OK; | |
378 | } | |
379 | ||
380 | static struct notifier_block tick_notifier = { | |
381 | .notifier_call = tick_notify, | |
382 | }; | |
383 | ||
384 | /** | |
385 | * tick_init - initialize the tick control | |
386 | * | |
387 | * Register the notifier with the clockevents framework | |
388 | */ | |
389 | void __init tick_init(void) | |
390 | { | |
391 | clockevents_register_notifier(&tick_notifier); | |
392 | } |