clk: ux500: Support for prcmu_scalable_rate clock
[linux-2.6.git] / kernel / time / tick-common.c
blobda6c9ecad4e47fc0758ed70d184eec8847400b20
1 /*
2 * linux/kernel/time/tick-common.c
4 * This file contains the base functions to manage periodic tick
5 * related events.
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/interrupt.h>
18 #include <linux/percpu.h>
19 #include <linux/profile.h>
20 #include <linux/sched.h>
22 #include <asm/irq_regs.h>
24 #include "tick-internal.h"
27 * Tick devices
29 DEFINE_PER_CPU(struct tick_device, tick_cpu_device);
31 * Tick next event: keeps track of the tick time
33 ktime_t tick_next_period;
34 ktime_t tick_period;
35 int tick_do_timer_cpu __read_mostly = TICK_DO_TIMER_BOOT;
36 static DEFINE_RAW_SPINLOCK(tick_device_lock);
39 * Debugging: see timer_list.c
41 struct tick_device *tick_get_device(int cpu)
43 return &per_cpu(tick_cpu_device, cpu);
46 /**
47 * tick_is_oneshot_available - check for a oneshot capable event device
49 int tick_is_oneshot_available(void)
51 struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev);
53 if (!dev || !(dev->features & CLOCK_EVT_FEAT_ONESHOT))
54 return 0;
55 if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
56 return 1;
57 return tick_broadcast_oneshot_available();
61 * Periodic tick
63 static void tick_periodic(int cpu)
65 if (tick_do_timer_cpu == cpu) {
66 write_seqlock(&xtime_lock);
68 /* Keep track of the next tick event */
69 tick_next_period = ktime_add(tick_next_period, tick_period);
71 do_timer(1);
72 write_sequnlock(&xtime_lock);
75 update_process_times(user_mode(get_irq_regs()));
76 profile_tick(CPU_PROFILING);
80 * Event handler for periodic ticks
82 void tick_handle_periodic(struct clock_event_device *dev)
84 int cpu = smp_processor_id();
85 ktime_t next;
87 tick_periodic(cpu);
89 if (dev->mode != CLOCK_EVT_MODE_ONESHOT)
90 return;
92 * Setup the next period for devices, which do not have
93 * periodic mode:
95 next = ktime_add(dev->next_event, tick_period);
96 for (;;) {
97 if (!clockevents_program_event(dev, next, false))
98 return;
100 * Have to be careful here. If we're in oneshot mode,
101 * before we call tick_periodic() in a loop, we need
102 * to be sure we're using a real hardware clocksource.
103 * Otherwise we could get trapped in an infinite
104 * loop, as the tick_periodic() increments jiffies,
105 * when then will increment time, posibly causing
106 * the loop to trigger again and again.
108 if (timekeeping_valid_for_hres())
109 tick_periodic(cpu);
110 next = ktime_add(next, tick_period);
115 * Setup the device for a periodic tick
117 void tick_setup_periodic(struct clock_event_device *dev, int broadcast)
119 tick_set_periodic_handler(dev, broadcast);
121 /* Broadcast setup ? */
122 if (!tick_device_is_functional(dev))
123 return;
125 if ((dev->features & CLOCK_EVT_FEAT_PERIODIC) &&
126 !tick_broadcast_oneshot_active()) {
127 clockevents_set_mode(dev, CLOCK_EVT_MODE_PERIODIC);
128 } else {
129 unsigned long seq;
130 ktime_t next;
132 do {
133 seq = read_seqbegin(&xtime_lock);
134 next = tick_next_period;
135 } while (read_seqretry(&xtime_lock, seq));
137 clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
139 for (;;) {
140 if (!clockevents_program_event(dev, next, false))
141 return;
142 next = ktime_add(next, tick_period);
148 * Setup the tick device
150 static void tick_setup_device(struct tick_device *td,
151 struct clock_event_device *newdev, int cpu,
152 const struct cpumask *cpumask)
154 ktime_t next_event;
155 void (*handler)(struct clock_event_device *) = NULL;
158 * First device setup ?
160 if (!td->evtdev) {
162 * If no cpu took the do_timer update, assign it to
163 * this cpu:
165 if (tick_do_timer_cpu == TICK_DO_TIMER_BOOT) {
166 tick_do_timer_cpu = cpu;
167 tick_next_period = ktime_get();
168 tick_period = ktime_set(0, NSEC_PER_SEC / HZ);
172 * Startup in periodic mode first.
174 td->mode = TICKDEV_MODE_PERIODIC;
175 } else {
176 handler = td->evtdev->event_handler;
177 next_event = td->evtdev->next_event;
178 td->evtdev->event_handler = clockevents_handle_noop;
181 td->evtdev = newdev;
184 * When the device is not per cpu, pin the interrupt to the
185 * current cpu:
187 if (!cpumask_equal(newdev->cpumask, cpumask))
188 irq_set_affinity(newdev->irq, cpumask);
191 * When global broadcasting is active, check if the current
192 * device is registered as a placeholder for broadcast mode.
193 * This allows us to handle this x86 misfeature in a generic
194 * way.
196 if (tick_device_uses_broadcast(newdev, cpu))
197 return;
199 if (td->mode == TICKDEV_MODE_PERIODIC)
200 tick_setup_periodic(newdev, 0);
201 else
202 tick_setup_oneshot(newdev, handler, next_event);
206 * Check, if the new registered device should be used.
208 static int tick_check_new_device(struct clock_event_device *newdev)
210 struct clock_event_device *curdev;
211 struct tick_device *td;
212 int cpu, ret = NOTIFY_OK;
213 unsigned long flags;
215 raw_spin_lock_irqsave(&tick_device_lock, flags);
217 cpu = smp_processor_id();
218 if (!cpumask_test_cpu(cpu, newdev->cpumask))
219 goto out_bc;
221 td = &per_cpu(tick_cpu_device, cpu);
222 curdev = td->evtdev;
224 /* cpu local device ? */
225 if (!cpumask_equal(newdev->cpumask, cpumask_of(cpu))) {
228 * If the cpu affinity of the device interrupt can not
229 * be set, ignore it.
231 if (!irq_can_set_affinity(newdev->irq))
232 goto out_bc;
235 * If we have a cpu local device already, do not replace it
236 * by a non cpu local device
238 if (curdev && cpumask_equal(curdev->cpumask, cpumask_of(cpu)))
239 goto out_bc;
243 * If we have an active device, then check the rating and the oneshot
244 * feature.
246 if (curdev) {
248 * Prefer one shot capable devices !
250 if ((curdev->features & CLOCK_EVT_FEAT_ONESHOT) &&
251 !(newdev->features & CLOCK_EVT_FEAT_ONESHOT))
252 goto out_bc;
254 * Check the rating
256 if (curdev->rating >= newdev->rating)
257 goto out_bc;
261 * Replace the eventually existing device by the new
262 * device. If the current device is the broadcast device, do
263 * not give it back to the clockevents layer !
265 if (tick_is_broadcast_device(curdev)) {
266 clockevents_shutdown(curdev);
267 curdev = NULL;
269 clockevents_exchange_device(curdev, newdev);
270 tick_setup_device(td, newdev, cpu, cpumask_of(cpu));
271 if (newdev->features & CLOCK_EVT_FEAT_ONESHOT)
272 tick_oneshot_notify();
274 raw_spin_unlock_irqrestore(&tick_device_lock, flags);
275 return NOTIFY_STOP;
277 out_bc:
279 * Can the new device be used as a broadcast device ?
281 if (tick_check_broadcast_device(newdev))
282 ret = NOTIFY_STOP;
284 raw_spin_unlock_irqrestore(&tick_device_lock, flags);
286 return ret;
290 * Transfer the do_timer job away from a dying cpu.
292 * Called with interrupts disabled.
294 static void tick_handover_do_timer(int *cpup)
296 if (*cpup == tick_do_timer_cpu) {
297 int cpu = cpumask_first(cpu_online_mask);
299 tick_do_timer_cpu = (cpu < nr_cpu_ids) ? cpu :
300 TICK_DO_TIMER_NONE;
305 * Shutdown an event device on a given cpu:
307 * This is called on a life CPU, when a CPU is dead. So we cannot
308 * access the hardware device itself.
309 * We just set the mode and remove it from the lists.
311 static void tick_shutdown(unsigned int *cpup)
313 struct tick_device *td = &per_cpu(tick_cpu_device, *cpup);
314 struct clock_event_device *dev = td->evtdev;
315 unsigned long flags;
317 raw_spin_lock_irqsave(&tick_device_lock, flags);
318 td->mode = TICKDEV_MODE_PERIODIC;
319 if (dev) {
321 * Prevent that the clock events layer tries to call
322 * the set mode function!
324 dev->mode = CLOCK_EVT_MODE_UNUSED;
325 clockevents_exchange_device(dev, NULL);
326 td->evtdev = NULL;
328 raw_spin_unlock_irqrestore(&tick_device_lock, flags);
331 static void tick_suspend(void)
333 struct tick_device *td = &__get_cpu_var(tick_cpu_device);
334 unsigned long flags;
336 raw_spin_lock_irqsave(&tick_device_lock, flags);
337 clockevents_shutdown(td->evtdev);
338 raw_spin_unlock_irqrestore(&tick_device_lock, flags);
341 static void tick_resume(void)
343 struct tick_device *td = &__get_cpu_var(tick_cpu_device);
344 unsigned long flags;
345 int broadcast = tick_resume_broadcast();
347 raw_spin_lock_irqsave(&tick_device_lock, flags);
348 clockevents_set_mode(td->evtdev, CLOCK_EVT_MODE_RESUME);
350 if (!broadcast) {
351 if (td->mode == TICKDEV_MODE_PERIODIC)
352 tick_setup_periodic(td->evtdev, 0);
353 else
354 tick_resume_oneshot();
356 raw_spin_unlock_irqrestore(&tick_device_lock, flags);
360 * Notification about clock event devices
362 static int tick_notify(struct notifier_block *nb, unsigned long reason,
363 void *dev)
365 switch (reason) {
367 case CLOCK_EVT_NOTIFY_ADD:
368 return tick_check_new_device(dev);
370 case CLOCK_EVT_NOTIFY_BROADCAST_ON:
371 case CLOCK_EVT_NOTIFY_BROADCAST_OFF:
372 case CLOCK_EVT_NOTIFY_BROADCAST_FORCE:
373 tick_broadcast_on_off(reason, dev);
374 break;
376 case CLOCK_EVT_NOTIFY_BROADCAST_ENTER:
377 case CLOCK_EVT_NOTIFY_BROADCAST_EXIT:
378 tick_broadcast_oneshot_control(reason);
379 break;
381 case CLOCK_EVT_NOTIFY_CPU_DYING:
382 tick_handover_do_timer(dev);
383 break;
385 case CLOCK_EVT_NOTIFY_CPU_DEAD:
386 tick_shutdown_broadcast_oneshot(dev);
387 tick_shutdown_broadcast(dev);
388 tick_shutdown(dev);
389 break;
391 case CLOCK_EVT_NOTIFY_SUSPEND:
392 tick_suspend();
393 tick_suspend_broadcast();
394 break;
396 case CLOCK_EVT_NOTIFY_RESUME:
397 tick_resume();
398 break;
400 default:
401 break;
404 return NOTIFY_OK;
407 static struct notifier_block tick_notifier = {
408 .notifier_call = tick_notify,
412 * tick_init - initialize the tick control
414 * Register the notifier with the clockevents framework
416 void __init tick_init(void)
418 clockevents_register_notifier(&tick_notifier);