blob: df12434b43ca09ec5ea9b0c48d679b842feddc9e [file] [log] [blame]
Thomas Gleixner906568c2007-02-16 01:28:01 -08001/*
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>
Russell Kingd7b90682008-04-17 07:46:24 +020017#include <linux/interrupt.h>
Thomas Gleixner906568c2007-02-16 01:28:01 -080018#include <linux/percpu.h>
19#include <linux/profile.h>
20#include <linux/sched.h>
21#include <linux/tick.h>
22
Russell Kingd7b90682008-04-17 07:46:24 +020023#include <asm/irq_regs.h>
24
Thomas Gleixnerf8381cb2007-02-16 01:28:02 -080025#include "tick-internal.h"
26
Thomas Gleixner906568c2007-02-16 01:28:01 -080027/*
28 * Tick devices
29 */
Thomas Gleixnerf8381cb2007-02-16 01:28:02 -080030DEFINE_PER_CPU(struct tick_device, tick_cpu_device);
Thomas Gleixner906568c2007-02-16 01:28:01 -080031/*
32 * Tick next event: keeps track of the tick time
33 */
Thomas Gleixnerf8381cb2007-02-16 01:28:02 -080034ktime_t tick_next_period;
35ktime_t tick_period;
Thomas Gleixner64414022008-09-22 18:46:37 +020036int tick_do_timer_cpu __read_mostly = TICK_DO_TIMER_BOOT;
Thomas Gleixnerf8381cb2007-02-16 01:28:02 -080037DEFINE_SPINLOCK(tick_device_lock);
Thomas Gleixner906568c2007-02-16 01:28:01 -080038
Ingo Molnar289f4802007-02-16 01:28:15 -080039/*
40 * Debugging: see timer_list.c
41 */
42struct tick_device *tick_get_device(int cpu)
43{
44 return &per_cpu(tick_cpu_device, cpu);
45}
46
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -080047/**
48 * tick_is_oneshot_available - check for a oneshot capable event device
49 */
50int 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
Thomas Gleixner906568c2007-02-16 01:28:01 -080057/*
58 * Periodic tick
59 */
60static 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 */
79void tick_handle_periodic(struct clock_event_device *dev)
80{
81 int cpu = smp_processor_id();
David S. Miller3494c162007-02-24 22:11:42 -080082 ktime_t next;
Thomas Gleixner906568c2007-02-16 01:28:01 -080083
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 */
David S. Miller3494c162007-02-24 22:11:42 -080092 next = ktime_add(dev->next_event, tick_period);
Thomas Gleixner906568c2007-02-16 01:28:01 -080093 for (;;) {
Thomas Gleixner906568c2007-02-16 01:28:01 -080094 if (!clockevents_program_event(dev, next, ktime_get()))
95 return;
96 tick_periodic(cpu);
David S. Miller3494c162007-02-24 22:11:42 -080097 next = ktime_add(next, tick_period);
Thomas Gleixner906568c2007-02-16 01:28:01 -080098 }
99}
100
101/*
102 * Setup the device for a periodic tick
103 */
Thomas Gleixnerf8381cb2007-02-16 01:28:02 -0800104void tick_setup_periodic(struct clock_event_device *dev, int broadcast)
Thomas Gleixner906568c2007-02-16 01:28:01 -0800105{
Thomas Gleixnerf8381cb2007-02-16 01:28:02 -0800106 tick_set_periodic_handler(dev, broadcast);
107
108 /* Broadcast setup ? */
109 if (!tick_device_is_functional(dev))
110 return;
Thomas Gleixner906568c2007-02-16 01:28:01 -0800111
Thomas Gleixner27ce4cb2008-09-22 19:04:02 +0200112 if ((dev->features & CLOCK_EVT_FEAT_PERIODIC) &&
113 !tick_broadcast_oneshot_active()) {
Thomas Gleixner906568c2007-02-16 01:28:01 -0800114 clockevents_set_mode(dev, CLOCK_EVT_MODE_PERIODIC);
115 } else {
116 unsigned long seq;
117 ktime_t next;
118
119 do {
120 seq = read_seqbegin(&xtime_lock);
121 next = tick_next_period;
122 } while (read_seqretry(&xtime_lock, seq));
123
124 clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
125
126 for (;;) {
127 if (!clockevents_program_event(dev, next, ktime_get()))
128 return;
129 next = ktime_add(next, tick_period);
130 }
131 }
132}
133
134/*
135 * Setup the tick device
136 */
137static void tick_setup_device(struct tick_device *td,
138 struct clock_event_device *newdev, int cpu,
Mike Travisc18a41f2008-07-15 14:14:34 -0700139 const cpumask_t *cpumask)
Thomas Gleixner906568c2007-02-16 01:28:01 -0800140{
141 ktime_t next_event;
142 void (*handler)(struct clock_event_device *) = NULL;
143
144 /*
145 * First device setup ?
146 */
147 if (!td->evtdev) {
148 /*
149 * If no cpu took the do_timer update, assign it to
150 * this cpu:
151 */
Thomas Gleixner64414022008-09-22 18:46:37 +0200152 if (tick_do_timer_cpu == TICK_DO_TIMER_BOOT) {
Thomas Gleixner906568c2007-02-16 01:28:01 -0800153 tick_do_timer_cpu = cpu;
154 tick_next_period = ktime_get();
155 tick_period = ktime_set(0, NSEC_PER_SEC / HZ);
156 }
157
158 /*
159 * Startup in periodic mode first.
160 */
161 td->mode = TICKDEV_MODE_PERIODIC;
162 } else {
163 handler = td->evtdev->event_handler;
164 next_event = td->evtdev->next_event;
Venkatesh Pallipadi7c1e7682008-09-03 21:36:50 +0000165 td->evtdev->event_handler = clockevents_handle_noop;
Thomas Gleixner906568c2007-02-16 01:28:01 -0800166 }
167
168 td->evtdev = newdev;
169
170 /*
171 * When the device is not per cpu, pin the interrupt to the
172 * current cpu:
173 */
Mike Travisc18a41f2008-07-15 14:14:34 -0700174 if (!cpus_equal(newdev->cpumask, *cpumask))
175 irq_set_affinity(newdev->irq, *cpumask);
Thomas Gleixner906568c2007-02-16 01:28:01 -0800176
Thomas Gleixnerf8381cb2007-02-16 01:28:02 -0800177 /*
178 * When global broadcasting is active, check if the current
179 * device is registered as a placeholder for broadcast mode.
180 * This allows us to handle this x86 misfeature in a generic
181 * way.
182 */
183 if (tick_device_uses_broadcast(newdev, cpu))
184 return;
185
Thomas Gleixner906568c2007-02-16 01:28:01 -0800186 if (td->mode == TICKDEV_MODE_PERIODIC)
187 tick_setup_periodic(newdev, 0);
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -0800188 else
189 tick_setup_oneshot(newdev, handler, next_event);
Thomas Gleixner906568c2007-02-16 01:28:01 -0800190}
191
192/*
193 * Check, if the new registered device should be used.
194 */
195static int tick_check_new_device(struct clock_event_device *newdev)
196{
197 struct clock_event_device *curdev;
198 struct tick_device *td;
199 int cpu, ret = NOTIFY_OK;
200 unsigned long flags;
Thomas Gleixner906568c2007-02-16 01:28:01 -0800201
202 spin_lock_irqsave(&tick_device_lock, flags);
203
204 cpu = smp_processor_id();
205 if (!cpu_isset(cpu, newdev->cpumask))
Venki Pallipadi4a932322007-10-12 23:04:23 +0200206 goto out_bc;
Thomas Gleixner906568c2007-02-16 01:28:01 -0800207
208 td = &per_cpu(tick_cpu_device, cpu);
209 curdev = td->evtdev;
Thomas Gleixner906568c2007-02-16 01:28:01 -0800210
211 /* cpu local device ? */
Mike Travis0bc3cc02008-07-24 18:21:31 -0700212 if (!cpus_equal(newdev->cpumask, cpumask_of_cpu(cpu))) {
Thomas Gleixner906568c2007-02-16 01:28:01 -0800213
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 */
Mike Travis0bc3cc02008-07-24 18:21:31 -0700225 if (curdev && cpus_equal(curdev->cpumask, cpumask_of_cpu(cpu)))
Thomas Gleixner906568c2007-02-16 01:28:01 -0800226 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) {
234 /*
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -0800235 * 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;
240 /*
Thomas Gleixner906568c2007-02-16 01:28:01 -0800241 * Check the rating
242 */
243 if (curdev->rating >= newdev->rating)
Thomas Gleixnerf8381cb2007-02-16 01:28:02 -0800244 goto out_bc;
Thomas Gleixner906568c2007-02-16 01:28:01 -0800245 }
246
247 /*
248 * Replace the eventually existing device by the new
Thomas Gleixnerf8381cb2007-02-16 01:28:02 -0800249 * device. If the current device is the broadcast device, do
250 * not give it back to the clockevents layer !
Thomas Gleixner906568c2007-02-16 01:28:01 -0800251 */
Thomas Gleixnerf8381cb2007-02-16 01:28:02 -0800252 if (tick_is_broadcast_device(curdev)) {
Thomas Gleixner2344abb2008-09-16 11:32:50 -0700253 clockevents_shutdown(curdev);
Thomas Gleixnerf8381cb2007-02-16 01:28:02 -0800254 curdev = NULL;
255 }
Thomas Gleixner906568c2007-02-16 01:28:01 -0800256 clockevents_exchange_device(curdev, newdev);
Mike Travis0bc3cc02008-07-24 18:21:31 -0700257 tick_setup_device(td, newdev, cpu, &cpumask_of_cpu(cpu));
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -0800258 if (newdev->features & CLOCK_EVT_FEAT_ONESHOT)
259 tick_oneshot_notify();
Thomas Gleixner906568c2007-02-16 01:28:01 -0800260
Thomas Gleixnerf8381cb2007-02-16 01:28:02 -0800261 spin_unlock_irqrestore(&tick_device_lock, flags);
262 return NOTIFY_STOP;
263
264out_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;
Venki Pallipadi4a932322007-10-12 23:04:23 +0200270
Thomas Gleixner906568c2007-02-16 01:28:01 -0800271 spin_unlock_irqrestore(&tick_device_lock, flags);
Thomas Gleixnerf8381cb2007-02-16 01:28:02 -0800272
Thomas Gleixner906568c2007-02-16 01:28:01 -0800273 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 */
283static 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 }
Thomas Gleixnerd3ed7822007-05-08 00:30:03 -0700300 /* 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
Thomas Gleixner64414022008-09-22 18:46:37 +0200304 tick_do_timer_cpu = (cpu != NR_CPUS) ? cpu :
305 TICK_DO_TIMER_NONE;
Thomas Gleixnerd3ed7822007-05-08 00:30:03 -0700306 }
Thomas Gleixner906568c2007-02-16 01:28:01 -0800307 spin_unlock_irqrestore(&tick_device_lock, flags);
308}
309
Thomas Gleixnercd05a1f2007-03-17 00:25:52 +0100310static void tick_suspend(void)
Thomas Gleixner6321dd62007-03-06 08:25:42 +0100311{
312 struct tick_device *td = &__get_cpu_var(tick_cpu_device);
313 unsigned long flags;
314
315 spin_lock_irqsave(&tick_device_lock, flags);
Thomas Gleixner2344abb2008-09-16 11:32:50 -0700316 clockevents_shutdown(td->evtdev);
Thomas Gleixner6321dd62007-03-06 08:25:42 +0100317 spin_unlock_irqrestore(&tick_device_lock, flags);
318}
319
Thomas Gleixnercd05a1f2007-03-17 00:25:52 +0100320static void tick_resume(void)
Thomas Gleixner6321dd62007-03-06 08:25:42 +0100321{
322 struct tick_device *td = &__get_cpu_var(tick_cpu_device);
323 unsigned long flags;
Thomas Gleixner18de5bc2007-07-21 04:37:34 -0700324 int broadcast = tick_resume_broadcast();
Thomas Gleixner6321dd62007-03-06 08:25:42 +0100325
326 spin_lock_irqsave(&tick_device_lock, flags);
Thomas Gleixner18de5bc2007-07-21 04:37:34 -0700327 clockevents_set_mode(td->evtdev, CLOCK_EVT_MODE_RESUME);
328
329 if (!broadcast) {
330 if (td->mode == TICKDEV_MODE_PERIODIC)
331 tick_setup_periodic(td->evtdev, 0);
332 else
333 tick_resume_oneshot();
334 }
Thomas Gleixner6321dd62007-03-06 08:25:42 +0100335 spin_unlock_irqrestore(&tick_device_lock, flags);
336}
337
Thomas Gleixner906568c2007-02-16 01:28:01 -0800338/*
339 * Notification about clock event devices
340 */
341static int tick_notify(struct notifier_block *nb, unsigned long reason,
342 void *dev)
343{
344 switch (reason) {
345
346 case CLOCK_EVT_NOTIFY_ADD:
347 return tick_check_new_device(dev);
348
Thomas Gleixnerf8381cb2007-02-16 01:28:02 -0800349 case CLOCK_EVT_NOTIFY_BROADCAST_ON:
350 case CLOCK_EVT_NOTIFY_BROADCAST_OFF:
Thomas Gleixner1595f452007-10-14 22:57:45 +0200351 case CLOCK_EVT_NOTIFY_BROADCAST_FORCE:
Thomas Gleixnerf8381cb2007-02-16 01:28:02 -0800352 tick_broadcast_on_off(reason, dev);
353 break;
354
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -0800355 case CLOCK_EVT_NOTIFY_BROADCAST_ENTER:
356 case CLOCK_EVT_NOTIFY_BROADCAST_EXIT:
357 tick_broadcast_oneshot_control(reason);
358 break;
359
Thomas Gleixner906568c2007-02-16 01:28:01 -0800360 case CLOCK_EVT_NOTIFY_CPU_DEAD:
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -0800361 tick_shutdown_broadcast_oneshot(dev);
Thomas Gleixnerf8381cb2007-02-16 01:28:02 -0800362 tick_shutdown_broadcast(dev);
Thomas Gleixner906568c2007-02-16 01:28:01 -0800363 tick_shutdown(dev);
364 break;
365
Thomas Gleixner6321dd62007-03-06 08:25:42 +0100366 case CLOCK_EVT_NOTIFY_SUSPEND:
Thomas Gleixnercd05a1f2007-03-17 00:25:52 +0100367 tick_suspend();
Thomas Gleixner6321dd62007-03-06 08:25:42 +0100368 tick_suspend_broadcast();
369 break;
370
371 case CLOCK_EVT_NOTIFY_RESUME:
Thomas Gleixner18de5bc2007-07-21 04:37:34 -0700372 tick_resume();
Thomas Gleixner6321dd62007-03-06 08:25:42 +0100373 break;
374
Thomas Gleixner906568c2007-02-16 01:28:01 -0800375 default:
376 break;
377 }
378
379 return NOTIFY_OK;
380}
381
382static struct notifier_block tick_notifier = {
383 .notifier_call = tick_notify,
384};
385
386/**
387 * tick_init - initialize the tick control
388 *
389 * Register the notifier with the clockevents framework
390 */
391void __init tick_init(void)
392{
393 clockevents_register_notifier(&tick_notifier);
394}