2 * linux/kernel/time/tick-broadcast.c
4 * This file contains functions which emulate a local clock-event
5 * device via a broadcast event source.
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
11 * This code is licenced under the GPL version 2. For details see
12 * kernel-base/COPYING.
14 #include <linux/cpu.h>
15 #include <linux/err.h>
16 #include <linux/hrtimer.h>
17 #include <linux/irq.h>
18 #include <linux/percpu.h>
19 #include <linux/profile.h>
20 #include <linux/sched.h>
21 #include <linux/tick.h>
23 #include "tick-internal.h"
26 * Broadcast support for broken x86 hardware, where the local apic
27 * timer stops in C3 state.
30 struct tick_device tick_broadcast_device;
31 static cpumask_t tick_broadcast_mask;
32 static DEFINE_SPINLOCK(tick_broadcast_lock);
35 * Debugging: see timer_list.c
37 struct tick_device *tick_get_broadcast_device(void)
39 return &tick_broadcast_device;
42 cpumask_t *tick_get_broadcast_mask(void)
44 return &tick_broadcast_mask;
48 * Start the device in periodic mode
50 static void tick_broadcast_start_periodic(struct clock_event_device *bc)
53 tick_setup_periodic(bc, 1);
57 * Check, if the device can be utilized as broadcast device:
59 int tick_check_broadcast_device(struct clock_event_device *dev)
61 if (tick_broadcast_device.evtdev ||
62 (dev->features & CLOCK_EVT_FEAT_C3STOP))
65 clockevents_exchange_device(NULL, dev);
66 tick_broadcast_device.evtdev = dev;
67 if (!cpus_empty(tick_broadcast_mask))
68 tick_broadcast_start_periodic(dev);
73 * Check, if the device is the broadcast device
75 int tick_is_broadcast_device(struct clock_event_device *dev)
77 return (dev && tick_broadcast_device.evtdev == dev);
81 * Check, if the device is disfunctional and a place holder, which
82 * needs to be handled by the broadcast device.
84 int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu)
89 spin_lock_irqsave(&tick_broadcast_lock, flags);
92 * Devices might be registered with both periodic and oneshot
93 * mode disabled. This signals, that the device needs to be
94 * operated from the broadcast device and is a placeholder for
95 * the cpu local device.
97 if (!tick_device_is_functional(dev)) {
98 dev->event_handler = tick_handle_periodic;
99 cpu_set(cpu, tick_broadcast_mask);
100 tick_broadcast_start_periodic(tick_broadcast_device.evtdev);
104 spin_unlock_irqrestore(&tick_broadcast_lock, flags);
109 * Broadcast the event to the cpus, which are set in the mask
111 int tick_do_broadcast(cpumask_t mask)
113 int ret = 0, cpu = smp_processor_id();
114 struct tick_device *td;
117 * Check, if the current cpu is in the mask
119 if (cpu_isset(cpu, mask)) {
120 cpu_clear(cpu, mask);
121 td = &per_cpu(tick_cpu_device, cpu);
122 td->evtdev->event_handler(td->evtdev);
126 if (!cpus_empty(mask)) {
128 * It might be necessary to actually check whether the devices
129 * have different broadcast functions. For now, just use the
130 * one of the first device. This works as long as we have this
131 * misfeature only on x86 (lapic)
133 cpu = first_cpu(mask);
134 td = &per_cpu(tick_cpu_device, cpu);
135 td->evtdev->broadcast(mask);
142 * Periodic broadcast:
143 * - invoke the broadcast handlers
145 static void tick_do_periodic_broadcast(void)
149 spin_lock(&tick_broadcast_lock);
151 cpus_and(mask, cpu_online_map, tick_broadcast_mask);
152 tick_do_broadcast(mask);
154 spin_unlock(&tick_broadcast_lock);
158 * Event handler for periodic broadcast ticks
160 static void tick_handle_periodic_broadcast(struct clock_event_device *dev)
162 dev->next_event.tv64 = KTIME_MAX;
164 tick_do_periodic_broadcast();
167 * The device is in periodic mode. No reprogramming necessary:
169 if (dev->mode == CLOCK_EVT_MODE_PERIODIC)
173 * Setup the next period for devices, which do not have
177 ktime_t next = ktime_add(dev->next_event, tick_period);
179 if (!clockevents_program_event(dev, next, ktime_get()))
181 tick_do_periodic_broadcast();
186 * Powerstate information: The system enters/leaves a state, where
187 * affected devices might stop
189 static void tick_do_broadcast_on_off(void *why)
191 struct clock_event_device *bc, *dev;
192 struct tick_device *td;
193 unsigned long flags, *reason = why;
196 spin_lock_irqsave(&tick_broadcast_lock, flags);
198 cpu = smp_processor_id();
199 td = &per_cpu(tick_cpu_device, cpu);
201 bc = tick_broadcast_device.evtdev;
204 * Is the device in broadcast mode forever or is it not
205 * affected by the powerstate ?
207 if (!dev || !tick_device_is_functional(dev) ||
208 !(dev->features & CLOCK_EVT_FEAT_C3STOP))
211 if (*reason == CLOCK_EVT_NOTIFY_BROADCAST_ON) {
212 if (!cpu_isset(cpu, tick_broadcast_mask)) {
213 cpu_set(cpu, tick_broadcast_mask);
214 if (td->mode == TICKDEV_MODE_PERIODIC)
215 clockevents_set_mode(dev,
216 CLOCK_EVT_MODE_SHUTDOWN);
219 if (cpu_isset(cpu, tick_broadcast_mask)) {
220 cpu_clear(cpu, tick_broadcast_mask);
221 if (td->mode == TICKDEV_MODE_PERIODIC)
222 tick_setup_periodic(dev, 0);
226 if (cpus_empty(tick_broadcast_mask))
227 clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);
229 if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
230 tick_broadcast_start_periodic(bc);
232 tick_broadcast_setup_oneshot(bc);
235 spin_unlock_irqrestore(&tick_broadcast_lock, flags);
239 * Powerstate information: The system enters/leaves a state, where
240 * affected devices might stop.
242 void tick_broadcast_on_off(unsigned long reason, int *oncpu)
246 if (!cpu_isset(*oncpu, cpu_online_map)) {
247 printk(KERN_ERR "tick-braodcast: ignoring broadcast for "
248 "offline CPU #%d\n", *oncpu);
252 tick_do_broadcast_on_off(&reason);
254 smp_call_function_single(*oncpu,
255 tick_do_broadcast_on_off,
262 * Set the periodic handler depending on broadcast on/off
264 void tick_set_periodic_handler(struct clock_event_device *dev, int broadcast)
267 dev->event_handler = tick_handle_periodic;
269 dev->event_handler = tick_handle_periodic_broadcast;
273 * Remove a CPU from broadcasting
275 void tick_shutdown_broadcast(unsigned int *cpup)
277 struct clock_event_device *bc;
279 unsigned int cpu = *cpup;
281 spin_lock_irqsave(&tick_broadcast_lock, flags);
283 bc = tick_broadcast_device.evtdev;
284 cpu_clear(cpu, tick_broadcast_mask);
286 if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) {
287 if (bc && cpus_empty(tick_broadcast_mask))
288 clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);
291 spin_unlock_irqrestore(&tick_broadcast_lock, flags);
294 void tick_suspend_broadcast(void)
296 struct clock_event_device *bc;
299 spin_lock_irqsave(&tick_broadcast_lock, flags);
301 bc = tick_broadcast_device.evtdev;
303 clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);
305 spin_unlock_irqrestore(&tick_broadcast_lock, flags);
308 int tick_resume_broadcast(void)
310 struct clock_event_device *bc;
314 spin_lock_irqsave(&tick_broadcast_lock, flags);
316 bc = tick_broadcast_device.evtdev;
319 clockevents_set_mode(bc, CLOCK_EVT_MODE_RESUME);
321 switch (tick_broadcast_device.mode) {
322 case TICKDEV_MODE_PERIODIC:
323 if(!cpus_empty(tick_broadcast_mask))
324 tick_broadcast_start_periodic(bc);
325 broadcast = cpu_isset(smp_processor_id(),
326 tick_broadcast_mask);
328 case TICKDEV_MODE_ONESHOT:
329 broadcast = tick_resume_broadcast_oneshot(bc);
333 spin_unlock_irqrestore(&tick_broadcast_lock, flags);
339 #ifdef CONFIG_TICK_ONESHOT
341 static cpumask_t tick_broadcast_oneshot_mask;
344 * Debugging: see timer_list.c
346 cpumask_t *tick_get_broadcast_oneshot_mask(void)
348 return &tick_broadcast_oneshot_mask;
351 static int tick_broadcast_set_event(ktime_t expires, int force)
353 struct clock_event_device *bc = tick_broadcast_device.evtdev;
354 ktime_t now = ktime_get();
358 res = clockevents_program_event(bc, expires, now);
362 expires = ktime_add(now, ktime_set(0, bc->min_delta_ns));
366 int tick_resume_broadcast_oneshot(struct clock_event_device *bc)
368 clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);
370 if(!cpus_empty(tick_broadcast_oneshot_mask))
371 tick_broadcast_set_event(ktime_get(), 1);
373 return cpu_isset(smp_processor_id(), tick_broadcast_oneshot_mask);
377 * Reprogram the broadcast device:
379 * Called with tick_broadcast_lock held and interrupts disabled.
381 static int tick_broadcast_reprogram(void)
383 ktime_t expires = { .tv64 = KTIME_MAX };
384 struct tick_device *td;
388 * Find the event which expires next:
390 for (cpu = first_cpu(tick_broadcast_oneshot_mask); cpu != NR_CPUS;
391 cpu = next_cpu(cpu, tick_broadcast_oneshot_mask)) {
392 td = &per_cpu(tick_cpu_device, cpu);
393 if (td->evtdev->next_event.tv64 < expires.tv64)
394 expires = td->evtdev->next_event;
397 if (expires.tv64 == KTIME_MAX)
400 return tick_broadcast_set_event(expires, 0);
404 * Handle oneshot mode broadcasting
406 static void tick_handle_oneshot_broadcast(struct clock_event_device *dev)
408 struct tick_device *td;
413 spin_lock(&tick_broadcast_lock);
415 dev->next_event.tv64 = KTIME_MAX;
416 mask = CPU_MASK_NONE;
418 /* Find all expired events */
419 for (cpu = first_cpu(tick_broadcast_oneshot_mask); cpu != NR_CPUS;
420 cpu = next_cpu(cpu, tick_broadcast_oneshot_mask)) {
421 td = &per_cpu(tick_cpu_device, cpu);
422 if (td->evtdev->next_event.tv64 <= now.tv64)
427 * Wakeup the cpus which have an expired event. The broadcast
428 * device is reprogrammed in the return from idle code.
430 if (!tick_do_broadcast(mask)) {
432 * The global event did not expire any CPU local
433 * events. This happens in dyntick mode, as the
434 * maximum PIT delta is quite small.
436 if (tick_broadcast_reprogram())
439 spin_unlock(&tick_broadcast_lock);
443 * Powerstate information: The system enters/leaves a state, where
444 * affected devices might stop
446 void tick_broadcast_oneshot_control(unsigned long reason)
448 struct clock_event_device *bc, *dev;
449 struct tick_device *td;
453 spin_lock_irqsave(&tick_broadcast_lock, flags);
456 * Periodic mode does not care about the enter/exit of power
459 if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
462 bc = tick_broadcast_device.evtdev;
463 cpu = smp_processor_id();
464 td = &per_cpu(tick_cpu_device, cpu);
467 if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
470 if (reason == CLOCK_EVT_NOTIFY_BROADCAST_ENTER) {
471 if (!cpu_isset(cpu, tick_broadcast_oneshot_mask)) {
472 cpu_set(cpu, tick_broadcast_oneshot_mask);
473 clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN);
474 if (dev->next_event.tv64 < bc->next_event.tv64)
475 tick_broadcast_set_event(dev->next_event, 1);
478 if (cpu_isset(cpu, tick_broadcast_oneshot_mask)) {
479 cpu_clear(cpu, tick_broadcast_oneshot_mask);
480 clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
481 if (dev->next_event.tv64 != KTIME_MAX)
482 tick_program_event(dev->next_event, 1);
487 spin_unlock_irqrestore(&tick_broadcast_lock, flags);
491 * tick_broadcast_setup_highres - setup the broadcast device for highres
493 void tick_broadcast_setup_oneshot(struct clock_event_device *bc)
495 if (bc->mode != CLOCK_EVT_MODE_ONESHOT) {
496 bc->event_handler = tick_handle_oneshot_broadcast;
497 clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);
498 bc->next_event.tv64 = KTIME_MAX;
503 * Select oneshot operating mode for the broadcast device
505 void tick_broadcast_switch_to_oneshot(void)
507 struct clock_event_device *bc;
510 spin_lock_irqsave(&tick_broadcast_lock, flags);
512 tick_broadcast_device.mode = TICKDEV_MODE_ONESHOT;
513 bc = tick_broadcast_device.evtdev;
515 tick_broadcast_setup_oneshot(bc);
516 spin_unlock_irqrestore(&tick_broadcast_lock, flags);
521 * Remove a dead CPU from broadcasting
523 void tick_shutdown_broadcast_oneshot(unsigned int *cpup)
525 struct clock_event_device *bc;
527 unsigned int cpu = *cpup;
529 spin_lock_irqsave(&tick_broadcast_lock, flags);
531 bc = tick_broadcast_device.evtdev;
532 cpu_clear(cpu, tick_broadcast_oneshot_mask);
534 if (tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT) {
535 if (bc && cpus_empty(tick_broadcast_oneshot_mask))
536 clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);
539 spin_unlock_irqrestore(&tick_broadcast_lock, flags);