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);
34 #ifdef CONFIG_TICK_ONESHOT
35 static void tick_broadcast_clear_oneshot(int cpu);
37 static inline void tick_broadcast_clear_oneshot(int cpu) { }
41 * Debugging: see timer_list.c
43 struct tick_device *tick_get_broadcast_device(void)
45 return &tick_broadcast_device;
48 cpumask_t *tick_get_broadcast_mask(void)
50 return &tick_broadcast_mask;
54 * Start the device in periodic mode
56 static void tick_broadcast_start_periodic(struct clock_event_device *bc)
59 tick_setup_periodic(bc, 1);
63 * Check, if the device can be utilized as broadcast device:
65 int tick_check_broadcast_device(struct clock_event_device *dev)
67 if (tick_broadcast_device.evtdev ||
68 (dev->features & CLOCK_EVT_FEAT_C3STOP))
71 clockevents_exchange_device(NULL, dev);
72 tick_broadcast_device.evtdev = dev;
73 if (!cpus_empty(tick_broadcast_mask))
74 tick_broadcast_start_periodic(dev);
79 * Check, if the device is the broadcast device
81 int tick_is_broadcast_device(struct clock_event_device *dev)
83 return (dev && tick_broadcast_device.evtdev == dev);
87 * Check, if the device is disfunctional and a place holder, which
88 * needs to be handled by the broadcast device.
90 int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu)
95 spin_lock_irqsave(&tick_broadcast_lock, flags);
98 * Devices might be registered with both periodic and oneshot
99 * mode disabled. This signals, that the device needs to be
100 * operated from the broadcast device and is a placeholder for
101 * the cpu local device.
103 if (!tick_device_is_functional(dev)) {
104 dev->event_handler = tick_handle_periodic;
105 cpu_set(cpu, tick_broadcast_mask);
106 tick_broadcast_start_periodic(tick_broadcast_device.evtdev);
110 * When the new device is not affected by the stop
111 * feature and the cpu is marked in the broadcast mask
112 * then clear the broadcast bit.
114 if (!(dev->features & CLOCK_EVT_FEAT_C3STOP)) {
115 int cpu = smp_processor_id();
117 cpu_clear(cpu, tick_broadcast_mask);
118 tick_broadcast_clear_oneshot(cpu);
121 spin_unlock_irqrestore(&tick_broadcast_lock, flags);
126 * Broadcast the event to the cpus, which are set in the mask
128 int tick_do_broadcast(cpumask_t mask)
130 int ret = 0, cpu = smp_processor_id();
131 struct tick_device *td;
134 * Check, if the current cpu is in the mask
136 if (cpu_isset(cpu, mask)) {
137 cpu_clear(cpu, mask);
138 td = &per_cpu(tick_cpu_device, cpu);
139 td->evtdev->event_handler(td->evtdev);
143 if (!cpus_empty(mask)) {
145 * It might be necessary to actually check whether the devices
146 * have different broadcast functions. For now, just use the
147 * one of the first device. This works as long as we have this
148 * misfeature only on x86 (lapic)
150 cpu = first_cpu(mask);
151 td = &per_cpu(tick_cpu_device, cpu);
152 td->evtdev->broadcast(mask);
159 * Periodic broadcast:
160 * - invoke the broadcast handlers
162 static void tick_do_periodic_broadcast(void)
166 spin_lock(&tick_broadcast_lock);
168 cpus_and(mask, cpu_online_map, tick_broadcast_mask);
169 tick_do_broadcast(mask);
171 spin_unlock(&tick_broadcast_lock);
175 * Event handler for periodic broadcast ticks
177 static void tick_handle_periodic_broadcast(struct clock_event_device *dev)
179 tick_do_periodic_broadcast();
182 * The device is in periodic mode. No reprogramming necessary:
184 if (dev->mode == CLOCK_EVT_MODE_PERIODIC)
188 * Setup the next period for devices, which do not have
192 ktime_t next = ktime_add(dev->next_event, tick_period);
194 if (!clockevents_program_event(dev, next, ktime_get()))
196 tick_do_periodic_broadcast();
201 * Powerstate information: The system enters/leaves a state, where
202 * affected devices might stop
204 static void tick_do_broadcast_on_off(void *why)
206 struct clock_event_device *bc, *dev;
207 struct tick_device *td;
208 unsigned long flags, *reason = why;
211 spin_lock_irqsave(&tick_broadcast_lock, flags);
213 cpu = smp_processor_id();
214 td = &per_cpu(tick_cpu_device, cpu);
216 bc = tick_broadcast_device.evtdev;
219 * Is the device in broadcast mode forever or is it not
220 * affected by the powerstate ?
222 if (!dev || !tick_device_is_functional(dev) ||
223 !(dev->features & CLOCK_EVT_FEAT_C3STOP))
226 if (*reason == CLOCK_EVT_NOTIFY_BROADCAST_ON) {
227 if (!cpu_isset(cpu, tick_broadcast_mask)) {
228 cpu_set(cpu, tick_broadcast_mask);
229 if (td->mode == TICKDEV_MODE_PERIODIC)
230 clockevents_set_mode(dev,
231 CLOCK_EVT_MODE_SHUTDOWN);
234 if (cpu_isset(cpu, tick_broadcast_mask)) {
235 cpu_clear(cpu, tick_broadcast_mask);
236 if (td->mode == TICKDEV_MODE_PERIODIC)
237 tick_setup_periodic(dev, 0);
241 if (cpus_empty(tick_broadcast_mask))
242 clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);
244 if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
245 tick_broadcast_start_periodic(bc);
247 tick_broadcast_setup_oneshot(bc);
250 spin_unlock_irqrestore(&tick_broadcast_lock, flags);
254 * Powerstate information: The system enters/leaves a state, where
255 * affected devices might stop.
257 void tick_broadcast_on_off(unsigned long reason, int *oncpu)
261 if (!cpu_isset(*oncpu, cpu_online_map)) {
262 printk(KERN_ERR "tick-braodcast: ignoring broadcast for "
263 "offline CPU #%d\n", *oncpu);
267 tick_do_broadcast_on_off(&reason);
269 smp_call_function_single(*oncpu,
270 tick_do_broadcast_on_off,
277 * Set the periodic handler depending on broadcast on/off
279 void tick_set_periodic_handler(struct clock_event_device *dev, int broadcast)
282 dev->event_handler = tick_handle_periodic;
284 dev->event_handler = tick_handle_periodic_broadcast;
288 * Remove a CPU from broadcasting
290 void tick_shutdown_broadcast(unsigned int *cpup)
292 struct clock_event_device *bc;
294 unsigned int cpu = *cpup;
296 spin_lock_irqsave(&tick_broadcast_lock, flags);
298 bc = tick_broadcast_device.evtdev;
299 cpu_clear(cpu, tick_broadcast_mask);
301 if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) {
302 if (bc && cpus_empty(tick_broadcast_mask))
303 clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);
306 spin_unlock_irqrestore(&tick_broadcast_lock, flags);
309 void tick_suspend_broadcast(void)
311 struct clock_event_device *bc;
314 spin_lock_irqsave(&tick_broadcast_lock, flags);
316 bc = tick_broadcast_device.evtdev;
318 clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);
320 spin_unlock_irqrestore(&tick_broadcast_lock, flags);
323 int tick_resume_broadcast(void)
325 struct clock_event_device *bc;
329 spin_lock_irqsave(&tick_broadcast_lock, flags);
331 bc = tick_broadcast_device.evtdev;
334 clockevents_set_mode(bc, CLOCK_EVT_MODE_RESUME);
336 switch (tick_broadcast_device.mode) {
337 case TICKDEV_MODE_PERIODIC:
338 if(!cpus_empty(tick_broadcast_mask))
339 tick_broadcast_start_periodic(bc);
340 broadcast = cpu_isset(smp_processor_id(),
341 tick_broadcast_mask);
343 case TICKDEV_MODE_ONESHOT:
344 broadcast = tick_resume_broadcast_oneshot(bc);
348 spin_unlock_irqrestore(&tick_broadcast_lock, flags);
354 #ifdef CONFIG_TICK_ONESHOT
356 static cpumask_t tick_broadcast_oneshot_mask;
359 * Debugging: see timer_list.c
361 cpumask_t *tick_get_broadcast_oneshot_mask(void)
363 return &tick_broadcast_oneshot_mask;
366 static int tick_broadcast_set_event(ktime_t expires, int force)
368 struct clock_event_device *bc = tick_broadcast_device.evtdev;
369 ktime_t now = ktime_get();
373 res = clockevents_program_event(bc, expires, now);
377 expires = ktime_add(now, ktime_set(0, bc->min_delta_ns));
381 int tick_resume_broadcast_oneshot(struct clock_event_device *bc)
383 clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);
388 * Reprogram the broadcast device:
390 * Called with tick_broadcast_lock held and interrupts disabled.
392 static int tick_broadcast_reprogram(void)
394 ktime_t expires = { .tv64 = KTIME_MAX };
395 struct tick_device *td;
399 * Find the event which expires next:
401 for (cpu = first_cpu(tick_broadcast_oneshot_mask); cpu != NR_CPUS;
402 cpu = next_cpu(cpu, tick_broadcast_oneshot_mask)) {
403 td = &per_cpu(tick_cpu_device, cpu);
404 if (td->evtdev->next_event.tv64 < expires.tv64)
405 expires = td->evtdev->next_event;
408 if (expires.tv64 == KTIME_MAX)
411 return tick_broadcast_set_event(expires, 0);
415 * Handle oneshot mode broadcasting
417 static void tick_handle_oneshot_broadcast(struct clock_event_device *dev)
419 struct tick_device *td;
424 spin_lock(&tick_broadcast_lock);
426 dev->next_event.tv64 = KTIME_MAX;
427 mask = CPU_MASK_NONE;
429 /* Find all expired events */
430 for (cpu = first_cpu(tick_broadcast_oneshot_mask); cpu != NR_CPUS;
431 cpu = next_cpu(cpu, tick_broadcast_oneshot_mask)) {
432 td = &per_cpu(tick_cpu_device, cpu);
433 if (td->evtdev->next_event.tv64 <= now.tv64)
438 * Wakeup the cpus which have an expired event. The broadcast
439 * device is reprogrammed in the return from idle code.
441 if (!tick_do_broadcast(mask)) {
443 * The global event did not expire any CPU local
444 * events. This happens in dyntick mode, as the
445 * maximum PIT delta is quite small.
447 if (tick_broadcast_reprogram())
450 spin_unlock(&tick_broadcast_lock);
454 * Powerstate information: The system enters/leaves a state, where
455 * affected devices might stop
457 void tick_broadcast_oneshot_control(unsigned long reason)
459 struct clock_event_device *bc, *dev;
460 struct tick_device *td;
464 spin_lock_irqsave(&tick_broadcast_lock, flags);
467 * Periodic mode does not care about the enter/exit of power
470 if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
473 bc = tick_broadcast_device.evtdev;
474 cpu = smp_processor_id();
475 td = &per_cpu(tick_cpu_device, cpu);
478 if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
481 if (reason == CLOCK_EVT_NOTIFY_BROADCAST_ENTER) {
482 if (!cpu_isset(cpu, tick_broadcast_oneshot_mask)) {
483 cpu_set(cpu, tick_broadcast_oneshot_mask);
484 clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN);
485 if (dev->next_event.tv64 < bc->next_event.tv64)
486 tick_broadcast_set_event(dev->next_event, 1);
489 if (cpu_isset(cpu, tick_broadcast_oneshot_mask)) {
490 cpu_clear(cpu, tick_broadcast_oneshot_mask);
491 clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
492 if (dev->next_event.tv64 != KTIME_MAX)
493 tick_program_event(dev->next_event, 1);
498 spin_unlock_irqrestore(&tick_broadcast_lock, flags);
502 * Reset the one shot broadcast for a cpu
504 * Called with tick_broadcast_lock held
506 static void tick_broadcast_clear_oneshot(int cpu)
508 cpu_clear(cpu, tick_broadcast_oneshot_mask);
512 * tick_broadcast_setup_highres - setup the broadcast device for highres
514 void tick_broadcast_setup_oneshot(struct clock_event_device *bc)
516 if (bc->mode != CLOCK_EVT_MODE_ONESHOT) {
517 bc->event_handler = tick_handle_oneshot_broadcast;
518 clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);
519 bc->next_event.tv64 = KTIME_MAX;
524 * Select oneshot operating mode for the broadcast device
526 void tick_broadcast_switch_to_oneshot(void)
528 struct clock_event_device *bc;
531 spin_lock_irqsave(&tick_broadcast_lock, flags);
533 tick_broadcast_device.mode = TICKDEV_MODE_ONESHOT;
534 bc = tick_broadcast_device.evtdev;
536 tick_broadcast_setup_oneshot(bc);
537 spin_unlock_irqrestore(&tick_broadcast_lock, flags);
542 * Remove a dead CPU from broadcasting
544 void tick_shutdown_broadcast_oneshot(unsigned int *cpup)
547 unsigned int cpu = *cpup;
549 spin_lock_irqsave(&tick_broadcast_lock, flags);
552 * Clear the broadcast mask flag for the dead cpu, but do not
553 * stop the broadcast device!
555 cpu_clear(cpu, tick_broadcast_oneshot_mask);
557 spin_unlock_irqrestore(&tick_broadcast_lock, flags);