2 * arch/s390/kernel/vtime.c
3 * Virtual cpu timer based timer functions.
6 * Copyright (C) 2004 IBM Deutschland Entwicklung GmbH, IBM Corporation
7 * Author(s): Jan Glauber <jan.glauber@de.ibm.com>
10 #include <linux/config.h>
11 #include <linux/module.h>
12 #include <linux/kernel.h>
13 #include <linux/time.h>
14 #include <linux/delay.h>
15 #include <linux/init.h>
16 #include <linux/smp.h>
17 #include <linux/types.h>
18 #include <linux/timex.h>
19 #include <linux/notifier.h>
20 #include <linux/kernel_stat.h>
21 #include <linux/rcupdate.h>
23 #include <asm/s390_ext.h>
24 #include <asm/timer.h>
26 #define VTIMER_MAGIC (TIMER_MAGIC + 1)
27 static ext_int_info_t ext_int_info_timer;
28 DEFINE_PER_CPU(struct vtimer_queue, virt_cpu_timer);
30 #ifdef CONFIG_VIRT_CPU_ACCOUNTING
32 * Update process times based on virtual cpu times stored by entry.S
33 * to the lowcore fields user_timer, system_timer & steal_clock.
35 void account_user_vtime(struct task_struct *tsk)
41 timer = S390_lowcore.last_update_timer;
42 clock = S390_lowcore.last_update_clock;
43 asm volatile (" STPT %0\n" /* Store current cpu timer value */
44 " STCK %1" /* Store current tod clock value */
45 : "=m" (S390_lowcore.last_update_timer),
46 "=m" (S390_lowcore.last_update_clock) );
47 S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer;
48 S390_lowcore.steal_clock += S390_lowcore.last_update_clock - clock;
50 cputime = S390_lowcore.user_timer >> 12;
51 rcu_user_flag = cputime != 0;
52 S390_lowcore.user_timer -= cputime << 12;
53 S390_lowcore.steal_clock -= cputime << 12;
54 account_user_time(tsk, cputime);
56 cputime = S390_lowcore.system_timer >> 12;
57 S390_lowcore.system_timer -= cputime << 12;
58 S390_lowcore.steal_clock -= cputime << 12;
59 account_system_time(tsk, HARDIRQ_OFFSET, cputime);
61 cputime = S390_lowcore.steal_clock;
62 if ((__s64) cputime > 0) {
64 S390_lowcore.steal_clock -= cputime << 12;
65 account_steal_time(tsk, cputime);
69 if (rcu_pending(smp_processor_id()))
70 rcu_check_callbacks(smp_processor_id(), rcu_user_flag);
75 * Update process times based on virtual cpu times stored by entry.S
76 * to the lowcore fields user_timer, system_timer & steal_clock.
78 void account_system_vtime(struct task_struct *tsk)
83 timer = S390_lowcore.last_update_timer;
84 asm volatile (" STPT %0" /* Store current cpu timer value */
85 : "=m" (S390_lowcore.last_update_timer) );
86 S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer;
88 cputime = S390_lowcore.system_timer >> 12;
89 S390_lowcore.system_timer -= cputime << 12;
90 S390_lowcore.steal_clock -= cputime << 12;
91 account_system_time(tsk, 0, cputime);
94 static inline void set_vtimer(__u64 expires)
98 asm volatile (" STPT %0\n" /* Store current cpu timer value */
99 " SPT %1" /* Set new value immediatly afterwards */
100 : "=m" (timer) : "m" (expires) );
101 S390_lowcore.system_timer += S390_lowcore.last_update_timer - timer;
102 S390_lowcore.last_update_timer = expires;
104 /* store expire time for this CPU timer */
105 per_cpu(virt_cpu_timer, smp_processor_id()).to_expire = expires;
108 static inline void set_vtimer(__u64 expires)
110 S390_lowcore.last_update_timer = expires;
111 asm volatile ("SPT %0" : : "m" (S390_lowcore.last_update_timer));
113 /* store expire time for this CPU timer */
114 per_cpu(virt_cpu_timer, smp_processor_id()).to_expire = expires;
118 static void start_cpu_timer(void)
120 struct vtimer_queue *vt_list;
122 vt_list = &per_cpu(virt_cpu_timer, smp_processor_id());
123 set_vtimer(vt_list->idle);
126 static void stop_cpu_timer(void)
129 struct vtimer_queue *vt_list;
131 vt_list = &per_cpu(virt_cpu_timer, smp_processor_id());
134 if (list_empty(&vt_list->list)) {
135 vt_list->idle = VTIMER_MAX_SLICE;
140 asm volatile ("STPT %0" : "=m" (done));
143 * If done is negative we do not stop the CPU timer
144 * because we will get instantly an interrupt that
145 * will start the CPU timer again.
150 vt_list->offset += vt_list->to_expire - done;
152 /* save the actual expire value */
153 vt_list->idle = done;
156 * We cannot halt the CPU timer, we just write a value that
157 * nearly never expires (only after 71 years) and re-write
158 * the stored expire value if we continue the timer
161 set_vtimer(VTIMER_MAX_SLICE);
165 * Sorted add to a list. List is linear searched until first bigger
168 static void list_add_sorted(struct vtimer_list *timer, struct list_head *head)
170 struct vtimer_list *event;
172 list_for_each_entry(event, head, entry) {
173 if (event->expires > timer->expires) {
174 list_add_tail(&timer->entry, &event->entry);
178 list_add_tail(&timer->entry, head);
182 * Do the callback functions of expired vtimer events.
183 * Called from within the interrupt handler.
185 static void do_callbacks(struct list_head *cb_list, struct pt_regs *regs)
187 struct vtimer_queue *vt_list;
188 struct vtimer_list *event, *tmp;
189 void (*fn)(unsigned long, struct pt_regs*);
192 if (list_empty(cb_list))
195 vt_list = &per_cpu(virt_cpu_timer, smp_processor_id());
197 list_for_each_entry_safe(event, tmp, cb_list, entry) {
198 fn = event->function;
202 if (!event->interval)
203 /* delete one shot timer */
204 list_del_init(&event->entry);
206 /* move interval timer back to list */
207 spin_lock(&vt_list->lock);
208 list_del_init(&event->entry);
209 list_add_sorted(event, &vt_list->list);
210 spin_unlock(&vt_list->lock);
216 * Handler for the virtual CPU timer.
218 static void do_cpu_timer_interrupt(struct pt_regs *regs, __u16 error_code)
222 struct vtimer_queue *vt_list;
223 struct vtimer_list *event, *tmp;
224 struct list_head *ptr;
225 /* the callback queue */
226 struct list_head cb_list;
228 INIT_LIST_HEAD(&cb_list);
229 cpu = smp_processor_id();
230 vt_list = &per_cpu(virt_cpu_timer, cpu);
232 /* walk timer list, fire all expired events */
233 spin_lock(&vt_list->lock);
235 if (vt_list->to_expire < VTIMER_MAX_SLICE)
236 vt_list->offset += vt_list->to_expire;
238 list_for_each_entry_safe(event, tmp, &vt_list->list, entry) {
239 if (event->expires > vt_list->offset)
240 /* found first unexpired event, leave */
243 /* re-charge interval timer, we have to add the offset */
245 event->expires = event->interval + vt_list->offset;
247 /* move expired timer to the callback queue */
248 list_move_tail(&event->entry, &cb_list);
250 spin_unlock(&vt_list->lock);
251 do_callbacks(&cb_list, regs);
253 /* next event is first in list */
254 spin_lock(&vt_list->lock);
255 if (!list_empty(&vt_list->list)) {
256 ptr = vt_list->list.next;
257 event = list_entry(ptr, struct vtimer_list, entry);
258 next = event->expires - vt_list->offset;
260 /* add the expired time from this interrupt handler
261 * and the callback functions
263 asm volatile ("STPT %0" : "=m" (delta));
264 delta = 0xffffffffffffffffLL - delta + 1;
265 vt_list->offset += delta;
269 next = VTIMER_MAX_SLICE;
271 spin_unlock(&vt_list->lock);
275 void init_virt_timer(struct vtimer_list *timer)
277 timer->magic = VTIMER_MAGIC;
278 timer->function = NULL;
279 INIT_LIST_HEAD(&timer->entry);
280 spin_lock_init(&timer->lock);
282 EXPORT_SYMBOL(init_virt_timer);
284 static inline int check_vtimer(struct vtimer_list *timer)
286 if (timer->magic != VTIMER_MAGIC)
291 static inline int vtimer_pending(struct vtimer_list *timer)
293 return (!list_empty(&timer->entry));
297 * this function should only run on the specified CPU
299 static void internal_add_vtimer(struct vtimer_list *timer)
303 struct vtimer_list *event;
304 struct vtimer_queue *vt_list;
306 vt_list = &per_cpu(virt_cpu_timer, timer->cpu);
307 spin_lock_irqsave(&vt_list->lock, flags);
309 if (timer->cpu != smp_processor_id())
310 printk("internal_add_vtimer: BUG, running on wrong CPU");
312 /* if list is empty we only have to set the timer */
313 if (list_empty(&vt_list->list)) {
314 /* reset the offset, this may happen if the last timer was
315 * just deleted by mod_virt_timer and the interrupt
316 * didn't happen until here
323 asm volatile ("STPT %0" : "=m" (done));
325 /* calculate completed work */
326 done = vt_list->to_expire - done + vt_list->offset;
329 list_for_each_entry(event, &vt_list->list, entry)
330 event->expires -= done;
333 list_add_sorted(timer, &vt_list->list);
335 /* get first element, which is the next vtimer slice */
336 event = list_entry(vt_list->list.next, struct vtimer_list, entry);
338 set_vtimer(event->expires);
339 spin_unlock_irqrestore(&vt_list->lock, flags);
340 /* release CPU aquired in prepare_vtimer or mod_virt_timer() */
344 static inline int prepare_vtimer(struct vtimer_list *timer)
346 if (check_vtimer(timer) || !timer->function) {
347 printk("add_virt_timer: uninitialized timer\n");
351 if (!timer->expires || timer->expires > VTIMER_MAX_SLICE) {
352 printk("add_virt_timer: invalid timer expire value!\n");
356 if (vtimer_pending(timer)) {
357 printk("add_virt_timer: timer pending\n");
361 timer->cpu = get_cpu();
366 * add_virt_timer - add an oneshot virtual CPU timer
368 void add_virt_timer(void *new)
370 struct vtimer_list *timer;
372 timer = (struct vtimer_list *)new;
374 if (prepare_vtimer(timer) < 0)
378 internal_add_vtimer(timer);
380 EXPORT_SYMBOL(add_virt_timer);
383 * add_virt_timer_int - add an interval virtual CPU timer
385 void add_virt_timer_periodic(void *new)
387 struct vtimer_list *timer;
389 timer = (struct vtimer_list *)new;
391 if (prepare_vtimer(timer) < 0)
394 timer->interval = timer->expires;
395 internal_add_vtimer(timer);
397 EXPORT_SYMBOL(add_virt_timer_periodic);
400 * If we change a pending timer the function must be called on the CPU
401 * where the timer is running on, e.g. by smp_call_function_on()
403 * The original mod_timer adds the timer if it is not pending. For compatibility
404 * we do the same. The timer will be added on the current CPU as a oneshot timer.
406 * returns whether it has modified a pending timer (1) or not (0)
408 int mod_virt_timer(struct vtimer_list *timer, __u64 expires)
410 struct vtimer_queue *vt_list;
414 if (check_vtimer(timer) || !timer->function) {
415 printk("mod_virt_timer: uninitialized timer\n");
419 if (!expires || expires > VTIMER_MAX_SLICE) {
420 printk("mod_virt_timer: invalid expire range\n");
425 * This is a common optimization triggered by the
426 * networking code - if the timer is re-modified
427 * to be the same thing then just return:
429 if (timer->expires == expires && vtimer_pending(timer))
433 vt_list = &per_cpu(virt_cpu_timer, cpu);
435 /* disable interrupts before test if timer is pending */
436 spin_lock_irqsave(&vt_list->lock, flags);
438 /* if timer isn't pending add it on the current CPU */
439 if (!vtimer_pending(timer)) {
440 spin_unlock_irqrestore(&vt_list->lock, flags);
441 /* we do not activate an interval timer with mod_virt_timer */
443 timer->expires = expires;
445 internal_add_vtimer(timer);
449 /* check if we run on the right CPU */
450 if (timer->cpu != cpu) {
451 printk("mod_virt_timer: running on wrong CPU, check your code\n");
452 spin_unlock_irqrestore(&vt_list->lock, flags);
457 list_del_init(&timer->entry);
458 timer->expires = expires;
460 /* also change the interval if we have an interval timer */
462 timer->interval = expires;
464 /* the timer can't expire anymore so we can release the lock */
465 spin_unlock_irqrestore(&vt_list->lock, flags);
466 internal_add_vtimer(timer);
469 EXPORT_SYMBOL(mod_virt_timer);
472 * delete a virtual timer
474 * returns whether the deleted timer was pending (1) or not (0)
476 int del_virt_timer(struct vtimer_list *timer)
479 struct vtimer_queue *vt_list;
481 if (check_vtimer(timer)) {
482 printk("del_virt_timer: timer not initialized\n");
486 /* check if timer is pending */
487 if (!vtimer_pending(timer))
490 vt_list = &per_cpu(virt_cpu_timer, timer->cpu);
491 spin_lock_irqsave(&vt_list->lock, flags);
493 /* we don't interrupt a running timer, just let it expire! */
494 list_del_init(&timer->entry);
496 /* last timer removed */
497 if (list_empty(&vt_list->list)) {
498 vt_list->to_expire = 0;
502 spin_unlock_irqrestore(&vt_list->lock, flags);
505 EXPORT_SYMBOL(del_virt_timer);
508 * Start the virtual CPU timer on the current CPU.
510 void init_cpu_vtimer(void)
512 struct vtimer_queue *vt_list;
515 /* kick the virtual timer */
516 S390_lowcore.exit_timer = VTIMER_MAX_SLICE;
517 S390_lowcore.last_update_timer = VTIMER_MAX_SLICE;
518 asm volatile ("SPT %0" : : "m" (S390_lowcore.last_update_timer));
519 asm volatile ("STCK %0" : "=m" (S390_lowcore.last_update_clock));
520 __ctl_store(cr0, 0, 0);
522 __ctl_load(cr0, 0, 0);
524 vt_list = &per_cpu(virt_cpu_timer, smp_processor_id());
525 INIT_LIST_HEAD(&vt_list->list);
526 spin_lock_init(&vt_list->lock);
527 vt_list->to_expire = 0;
533 static int vtimer_idle_notify(struct notifier_block *self,
534 unsigned long action, void *hcpu)
547 static struct notifier_block vtimer_idle_nb = {
548 .notifier_call = vtimer_idle_notify,
551 void __init vtime_init(void)
553 /* request the cpu timer external interrupt */
554 if (register_early_external_interrupt(0x1005, do_cpu_timer_interrupt,
555 &ext_int_info_timer) != 0)
556 panic("Couldn't request external interrupt 0x1005");
558 if (register_idle_notifier(&vtimer_idle_nb))
559 panic("Couldn't register idle notifier");