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> | |
409d4ffa | 21 | #include <linux/module.h> |
906568c9 | 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 | { | |
909ea964 | 52 | struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev); |
79bf2bb3 | 53 | |
3a142a06 TG |
54 | if (!dev || !(dev->features & CLOCK_EVT_FEAT_ONESHOT)) |
55 | return 0; | |
56 | if (!(dev->features & CLOCK_EVT_FEAT_C3STOP)) | |
57 | return 1; | |
58 | return tick_broadcast_oneshot_available(); | |
79bf2bb3 TG |
59 | } |
60 | ||
906568c9 TG |
61 | /* |
62 | * Periodic tick | |
63 | */ | |
64 | static void tick_periodic(int cpu) | |
65 | { | |
66 | if (tick_do_timer_cpu == cpu) { | |
d6ad4187 | 67 | write_seqlock(&jiffies_lock); |
906568c9 TG |
68 | |
69 | /* Keep track of the next tick event */ | |
70 | tick_next_period = ktime_add(tick_next_period, tick_period); | |
71 | ||
72 | do_timer(1); | |
d6ad4187 | 73 | write_sequnlock(&jiffies_lock); |
906568c9 TG |
74 | } |
75 | ||
76 | update_process_times(user_mode(get_irq_regs())); | |
77 | profile_tick(CPU_PROFILING); | |
78 | } | |
79 | ||
80 | /* | |
81 | * Event handler for periodic ticks | |
82 | */ | |
83 | void tick_handle_periodic(struct clock_event_device *dev) | |
84 | { | |
85 | int cpu = smp_processor_id(); | |
3494c166 | 86 | ktime_t next; |
906568c9 TG |
87 | |
88 | tick_periodic(cpu); | |
89 | ||
90 | if (dev->mode != CLOCK_EVT_MODE_ONESHOT) | |
91 | return; | |
92 | /* | |
93 | * Setup the next period for devices, which do not have | |
94 | * periodic mode: | |
95 | */ | |
3494c166 | 96 | next = ktime_add(dev->next_event, tick_period); |
906568c9 | 97 | for (;;) { |
d1748302 | 98 | if (!clockevents_program_event(dev, next, false)) |
906568c9 | 99 | return; |
74a03b69 JS |
100 | /* |
101 | * Have to be careful here. If we're in oneshot mode, | |
102 | * before we call tick_periodic() in a loop, we need | |
103 | * to be sure we're using a real hardware clocksource. | |
104 | * Otherwise we could get trapped in an infinite | |
105 | * loop, as the tick_periodic() increments jiffies, | |
106 | * when then will increment time, posibly causing | |
107 | * the loop to trigger again and again. | |
108 | */ | |
109 | if (timekeeping_valid_for_hres()) | |
110 | tick_periodic(cpu); | |
3494c166 | 111 | next = ktime_add(next, tick_period); |
906568c9 TG |
112 | } |
113 | } | |
114 | ||
115 | /* | |
116 | * Setup the device for a periodic tick | |
117 | */ | |
f8381cba | 118 | void tick_setup_periodic(struct clock_event_device *dev, int broadcast) |
906568c9 | 119 | { |
f8381cba TG |
120 | tick_set_periodic_handler(dev, broadcast); |
121 | ||
122 | /* Broadcast setup ? */ | |
123 | if (!tick_device_is_functional(dev)) | |
124 | return; | |
906568c9 | 125 | |
27ce4cb4 TG |
126 | if ((dev->features & CLOCK_EVT_FEAT_PERIODIC) && |
127 | !tick_broadcast_oneshot_active()) { | |
906568c9 TG |
128 | clockevents_set_mode(dev, CLOCK_EVT_MODE_PERIODIC); |
129 | } else { | |
130 | unsigned long seq; | |
131 | ktime_t next; | |
132 | ||
133 | do { | |
d6ad4187 | 134 | seq = read_seqbegin(&jiffies_lock); |
906568c9 | 135 | next = tick_next_period; |
d6ad4187 | 136 | } while (read_seqretry(&jiffies_lock, seq)); |
906568c9 TG |
137 | |
138 | clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT); | |
139 | ||
140 | for (;;) { | |
d1748302 | 141 | if (!clockevents_program_event(dev, next, false)) |
906568c9 TG |
142 | return; |
143 | next = ktime_add(next, tick_period); | |
144 | } | |
145 | } | |
146 | } | |
147 | ||
148 | /* | |
149 | * Setup the tick device | |
150 | */ | |
151 | static void tick_setup_device(struct tick_device *td, | |
152 | struct clock_event_device *newdev, int cpu, | |
0de26520 | 153 | const struct cpumask *cpumask) |
906568c9 TG |
154 | { |
155 | ktime_t next_event; | |
156 | void (*handler)(struct clock_event_device *) = NULL; | |
157 | ||
158 | /* | |
159 | * First device setup ? | |
160 | */ | |
161 | if (!td->evtdev) { | |
162 | /* | |
163 | * If no cpu took the do_timer update, assign it to | |
164 | * this cpu: | |
165 | */ | |
6441402b | 166 | if (tick_do_timer_cpu == TICK_DO_TIMER_BOOT) { |
c5bfece2 | 167 | if (!tick_nohz_full_cpu(cpu)) |
a382bf93 FW |
168 | tick_do_timer_cpu = cpu; |
169 | else | |
170 | tick_do_timer_cpu = TICK_DO_TIMER_NONE; | |
906568c9 TG |
171 | tick_next_period = ktime_get(); |
172 | tick_period = ktime_set(0, NSEC_PER_SEC / HZ); | |
173 | } | |
174 | ||
175 | /* | |
176 | * Startup in periodic mode first. | |
177 | */ | |
178 | td->mode = TICKDEV_MODE_PERIODIC; | |
179 | } else { | |
180 | handler = td->evtdev->event_handler; | |
181 | next_event = td->evtdev->next_event; | |
7c1e7689 | 182 | td->evtdev->event_handler = clockevents_handle_noop; |
906568c9 TG |
183 | } |
184 | ||
185 | td->evtdev = newdev; | |
186 | ||
187 | /* | |
188 | * When the device is not per cpu, pin the interrupt to the | |
189 | * current cpu: | |
190 | */ | |
320ab2b0 | 191 | if (!cpumask_equal(newdev->cpumask, cpumask)) |
0de26520 | 192 | irq_set_affinity(newdev->irq, cpumask); |
906568c9 | 193 | |
f8381cba TG |
194 | /* |
195 | * When global broadcasting is active, check if the current | |
196 | * device is registered as a placeholder for broadcast mode. | |
197 | * This allows us to handle this x86 misfeature in a generic | |
1c0d08e6 TG |
198 | * way. This function also returns !=0 when we keep the |
199 | * current active broadcast state for this CPU. | |
f8381cba TG |
200 | */ |
201 | if (tick_device_uses_broadcast(newdev, cpu)) | |
202 | return; | |
203 | ||
906568c9 TG |
204 | if (td->mode == TICKDEV_MODE_PERIODIC) |
205 | tick_setup_periodic(newdev, 0); | |
79bf2bb3 TG |
206 | else |
207 | tick_setup_oneshot(newdev, handler, next_event); | |
906568c9 TG |
208 | } |
209 | ||
9bae8ea0 TG |
210 | static bool tick_check_percpu(struct clock_event_device *curdev, |
211 | struct clock_event_device *newdev, int cpu) | |
212 | { | |
213 | if (!cpumask_test_cpu(cpu, newdev->cpumask)) | |
214 | return false; | |
215 | if (cpumask_equal(newdev->cpumask, cpumask_of(cpu))) | |
216 | return true; | |
217 | /* Check if irq affinity can be set */ | |
218 | if (newdev->irq >= 0 && !irq_can_set_affinity(newdev->irq)) | |
219 | return false; | |
220 | /* Prefer an existing cpu local device */ | |
221 | if (curdev && cpumask_equal(curdev->cpumask, cpumask_of(cpu))) | |
222 | return false; | |
223 | return true; | |
224 | } | |
225 | ||
226 | static bool tick_check_preferred(struct clock_event_device *curdev, | |
227 | struct clock_event_device *newdev) | |
228 | { | |
229 | /* Prefer oneshot capable device */ | |
230 | if (!(newdev->features & CLOCK_EVT_FEAT_ONESHOT)) { | |
231 | if (curdev && (curdev->features & CLOCK_EVT_FEAT_ONESHOT)) | |
232 | return false; | |
233 | if (tick_oneshot_mode_active()) | |
234 | return false; | |
235 | } | |
236 | ||
7281bb56 SB |
237 | /* |
238 | * Use the higher rated one, but prefer a CPU local device with a lower | |
239 | * rating than a non-CPU local device | |
240 | */ | |
241 | return !curdev || | |
242 | newdev->rating > curdev->rating || | |
243 | !cpumask_equal(curdev->cpumask, newdev->cpumask); | |
9bae8ea0 TG |
244 | } |
245 | ||
906568c9 TG |
246 | /* |
247 | * Check, if the new registered device should be used. | |
248 | */ | |
e8d63033 | 249 | void tick_check_new_device(struct clock_event_device *newdev) |
906568c9 TG |
250 | { |
251 | struct clock_event_device *curdev; | |
252 | struct tick_device *td; | |
e8d63033 | 253 | int cpu; |
906568c9 | 254 | unsigned long flags; |
906568c9 | 255 | |
b5f91da0 | 256 | raw_spin_lock_irqsave(&tick_device_lock, flags); |
906568c9 TG |
257 | |
258 | cpu = smp_processor_id(); | |
320ab2b0 | 259 | if (!cpumask_test_cpu(cpu, newdev->cpumask)) |
4a93232d | 260 | goto out_bc; |
906568c9 TG |
261 | |
262 | td = &per_cpu(tick_cpu_device, cpu); | |
263 | curdev = td->evtdev; | |
906568c9 TG |
264 | |
265 | /* cpu local device ? */ | |
9bae8ea0 TG |
266 | if (!tick_check_percpu(curdev, newdev, cpu)) |
267 | goto out_bc; | |
906568c9 | 268 | |
9bae8ea0 TG |
269 | /* Preference decision */ |
270 | if (!tick_check_preferred(curdev, newdev)) | |
271 | goto out_bc; | |
906568c9 | 272 | |
409d4ffa TG |
273 | if (!try_module_get(newdev->owner)) |
274 | return; | |
275 | ||
906568c9 TG |
276 | /* |
277 | * Replace the eventually existing device by the new | |
f8381cba TG |
278 | * device. If the current device is the broadcast device, do |
279 | * not give it back to the clockevents layer ! | |
906568c9 | 280 | */ |
f8381cba | 281 | if (tick_is_broadcast_device(curdev)) { |
2344abbc | 282 | clockevents_shutdown(curdev); |
f8381cba TG |
283 | curdev = NULL; |
284 | } | |
906568c9 | 285 | clockevents_exchange_device(curdev, newdev); |
6b954823 | 286 | tick_setup_device(td, newdev, cpu, cpumask_of(cpu)); |
79bf2bb3 TG |
287 | if (newdev->features & CLOCK_EVT_FEAT_ONESHOT) |
288 | tick_oneshot_notify(); | |
906568c9 | 289 | |
b5f91da0 | 290 | raw_spin_unlock_irqrestore(&tick_device_lock, flags); |
e8d63033 | 291 | return; |
f8381cba TG |
292 | |
293 | out_bc: | |
294 | /* | |
295 | * Can the new device be used as a broadcast device ? | |
296 | */ | |
e8d63033 | 297 | tick_install_broadcast_device(newdev); |
b5f91da0 | 298 | raw_spin_unlock_irqrestore(&tick_device_lock, flags); |
906568c9 TG |
299 | } |
300 | ||
94df7de0 SD |
301 | /* |
302 | * Transfer the do_timer job away from a dying cpu. | |
303 | * | |
304 | * Called with interrupts disabled. | |
305 | */ | |
306 | static void tick_handover_do_timer(int *cpup) | |
307 | { | |
308 | if (*cpup == tick_do_timer_cpu) { | |
309 | int cpu = cpumask_first(cpu_online_mask); | |
310 | ||
311 | tick_do_timer_cpu = (cpu < nr_cpu_ids) ? cpu : | |
312 | TICK_DO_TIMER_NONE; | |
313 | } | |
314 | } | |
315 | ||
906568c9 TG |
316 | /* |
317 | * Shutdown an event device on a given cpu: | |
318 | * | |
319 | * This is called on a life CPU, when a CPU is dead. So we cannot | |
320 | * access the hardware device itself. | |
321 | * We just set the mode and remove it from the lists. | |
322 | */ | |
323 | static void tick_shutdown(unsigned int *cpup) | |
324 | { | |
325 | struct tick_device *td = &per_cpu(tick_cpu_device, *cpup); | |
326 | struct clock_event_device *dev = td->evtdev; | |
327 | unsigned long flags; | |
328 | ||
b5f91da0 | 329 | raw_spin_lock_irqsave(&tick_device_lock, flags); |
906568c9 TG |
330 | td->mode = TICKDEV_MODE_PERIODIC; |
331 | if (dev) { | |
332 | /* | |
333 | * Prevent that the clock events layer tries to call | |
334 | * the set mode function! | |
335 | */ | |
336 | dev->mode = CLOCK_EVT_MODE_UNUSED; | |
337 | clockevents_exchange_device(dev, NULL); | |
6f7a05d7 | 338 | dev->event_handler = clockevents_handle_noop; |
906568c9 TG |
339 | td->evtdev = NULL; |
340 | } | |
b5f91da0 | 341 | raw_spin_unlock_irqrestore(&tick_device_lock, flags); |
906568c9 TG |
342 | } |
343 | ||
cd05a1f8 | 344 | static void tick_suspend(void) |
6321dd60 TG |
345 | { |
346 | struct tick_device *td = &__get_cpu_var(tick_cpu_device); | |
347 | unsigned long flags; | |
348 | ||
b5f91da0 | 349 | raw_spin_lock_irqsave(&tick_device_lock, flags); |
2344abbc | 350 | clockevents_shutdown(td->evtdev); |
b5f91da0 | 351 | raw_spin_unlock_irqrestore(&tick_device_lock, flags); |
6321dd60 TG |
352 | } |
353 | ||
cd05a1f8 | 354 | static void tick_resume(void) |
6321dd60 TG |
355 | { |
356 | struct tick_device *td = &__get_cpu_var(tick_cpu_device); | |
357 | unsigned long flags; | |
18de5bc4 | 358 | int broadcast = tick_resume_broadcast(); |
6321dd60 | 359 | |
b5f91da0 | 360 | raw_spin_lock_irqsave(&tick_device_lock, flags); |
18de5bc4 TG |
361 | clockevents_set_mode(td->evtdev, CLOCK_EVT_MODE_RESUME); |
362 | ||
363 | if (!broadcast) { | |
364 | if (td->mode == TICKDEV_MODE_PERIODIC) | |
365 | tick_setup_periodic(td->evtdev, 0); | |
366 | else | |
367 | tick_resume_oneshot(); | |
368 | } | |
b5f91da0 | 369 | raw_spin_unlock_irqrestore(&tick_device_lock, flags); |
6321dd60 TG |
370 | } |
371 | ||
e8d63033 | 372 | void tick_notify(unsigned long reason, void *dev) |
906568c9 TG |
373 | { |
374 | switch (reason) { | |
375 | ||
f8381cba TG |
376 | case CLOCK_EVT_NOTIFY_BROADCAST_ON: |
377 | case CLOCK_EVT_NOTIFY_BROADCAST_OFF: | |
1595f452 | 378 | case CLOCK_EVT_NOTIFY_BROADCAST_FORCE: |
f8381cba TG |
379 | tick_broadcast_on_off(reason, dev); |
380 | break; | |
381 | ||
79bf2bb3 TG |
382 | case CLOCK_EVT_NOTIFY_BROADCAST_ENTER: |
383 | case CLOCK_EVT_NOTIFY_BROADCAST_EXIT: | |
384 | tick_broadcast_oneshot_control(reason); | |
385 | break; | |
386 | ||
94df7de0 SD |
387 | case CLOCK_EVT_NOTIFY_CPU_DYING: |
388 | tick_handover_do_timer(dev); | |
389 | break; | |
390 | ||
906568c9 | 391 | case CLOCK_EVT_NOTIFY_CPU_DEAD: |
79bf2bb3 | 392 | tick_shutdown_broadcast_oneshot(dev); |
f8381cba | 393 | tick_shutdown_broadcast(dev); |
906568c9 TG |
394 | tick_shutdown(dev); |
395 | break; | |
396 | ||
6321dd60 | 397 | case CLOCK_EVT_NOTIFY_SUSPEND: |
cd05a1f8 | 398 | tick_suspend(); |
6321dd60 TG |
399 | tick_suspend_broadcast(); |
400 | break; | |
401 | ||
402 | case CLOCK_EVT_NOTIFY_RESUME: | |
18de5bc4 | 403 | tick_resume(); |
6321dd60 TG |
404 | break; |
405 | ||
906568c9 TG |
406 | default: |
407 | break; | |
408 | } | |
906568c9 TG |
409 | } |
410 | ||
906568c9 TG |
411 | /** |
412 | * tick_init - initialize the tick control | |
906568c9 TG |
413 | */ |
414 | void __init tick_init(void) | |
415 | { | |
b352bc1c | 416 | tick_broadcast_init(); |
906568c9 | 417 | } |