2 * linux/kernel/irq/manage.c
4 * Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
5 * Copyright (C) 2005-2006 Thomas Gleixner
7 * This file contains driver APIs to the irq subsystem.
10 #include <linux/irq.h>
11 #include <linux/kthread.h>
12 #include <linux/module.h>
13 #include <linux/random.h>
14 #include <linux/interrupt.h>
15 #include <linux/slab.h>
16 #include <linux/sched.h>
18 #include "internals.h"
21 * synchronize_irq - wait for pending IRQ handlers (on other CPUs)
22 * @irq: interrupt number to wait for
24 * This function waits for any pending IRQ handlers for this interrupt
25 * to complete before returning. If you use this function while
26 * holding a resource the IRQ handler may need you will deadlock.
28 * This function may be called - with care - from IRQ context.
30 void synchronize_irq(unsigned int irq)
32 struct irq_desc *desc = irq_to_desc(irq);
42 * Wait until we're out of the critical section. This might
43 * give the wrong answer due to the lack of memory barriers.
45 while (desc->status & IRQ_INPROGRESS)
48 /* Ok, that indicated we're done: double-check carefully. */
49 spin_lock_irqsave(&desc->lock, flags);
50 status = desc->status;
51 spin_unlock_irqrestore(&desc->lock, flags);
53 /* Oops, that failed? */
54 } while (status & IRQ_INPROGRESS);
57 * We made sure that no hardirq handler is running. Now verify
58 * that no threaded handlers are active.
60 wait_event(desc->wait_for_threads, !atomic_read(&desc->threads_active));
62 EXPORT_SYMBOL(synchronize_irq);
65 cpumask_var_t irq_default_affinity;
68 * irq_can_set_affinity - Check if the affinity of a given irq can be set
69 * @irq: Interrupt to check
72 int irq_can_set_affinity(unsigned int irq)
74 struct irq_desc *desc = irq_to_desc(irq);
76 if (CHECK_IRQ_PER_CPU(desc->status) || !desc->chip ||
77 !desc->chip->set_affinity)
84 irq_set_thread_affinity(struct irq_desc *desc, const struct cpumask *cpumask)
86 struct irqaction *action = desc->action;
90 set_cpus_allowed_ptr(action->thread, cpumask);
91 action = action->next;
96 * irq_set_affinity - Set the irq affinity of a given irq
97 * @irq: Interrupt to set affinity
101 int irq_set_affinity(unsigned int irq, const struct cpumask *cpumask)
103 struct irq_desc *desc = irq_to_desc(irq);
106 if (!desc->chip->set_affinity)
109 spin_lock_irqsave(&desc->lock, flags);
111 #ifdef CONFIG_GENERIC_PENDING_IRQ
112 if (desc->status & IRQ_MOVE_PCNTXT || desc->status & IRQ_DISABLED) {
113 cpumask_copy(desc->affinity, cpumask);
114 desc->chip->set_affinity(irq, cpumask);
116 desc->status |= IRQ_MOVE_PENDING;
117 cpumask_copy(desc->pending_mask, cpumask);
120 cpumask_copy(desc->affinity, cpumask);
121 desc->chip->set_affinity(irq, cpumask);
123 irq_set_thread_affinity(desc, cpumask);
124 desc->status |= IRQ_AFFINITY_SET;
125 spin_unlock_irqrestore(&desc->lock, flags);
129 #ifndef CONFIG_AUTO_IRQ_AFFINITY
131 * Generic version of the affinity autoselector.
133 static int setup_affinity(unsigned int irq, struct irq_desc *desc)
135 if (!irq_can_set_affinity(irq))
139 * Preserve an userspace affinity setup, but make sure that
140 * one of the targets is online.
142 if (desc->status & (IRQ_AFFINITY_SET | IRQ_NO_BALANCING)) {
143 if (cpumask_any_and(desc->affinity, cpu_online_mask)
147 desc->status &= ~IRQ_AFFINITY_SET;
150 cpumask_and(desc->affinity, cpu_online_mask, irq_default_affinity);
152 desc->chip->set_affinity(irq, desc->affinity);
157 static inline int setup_affinity(unsigned int irq, struct irq_desc *d)
159 return irq_select_affinity(irq);
164 * Called when affinity is set via /proc/irq
166 int irq_select_affinity_usr(unsigned int irq)
168 struct irq_desc *desc = irq_to_desc(irq);
172 spin_lock_irqsave(&desc->lock, flags);
173 ret = setup_affinity(irq, desc);
175 irq_set_thread_affinity(desc, desc->affinity);
176 spin_unlock_irqrestore(&desc->lock, flags);
182 static inline int setup_affinity(unsigned int irq, struct irq_desc *desc)
189 * disable_irq_nosync - disable an irq without waiting
190 * @irq: Interrupt to disable
192 * Disable the selected interrupt line. Disables and Enables are
194 * Unlike disable_irq(), this function does not ensure existing
195 * instances of the IRQ handler have completed before returning.
197 * This function may be called from IRQ context.
199 void disable_irq_nosync(unsigned int irq)
201 struct irq_desc *desc = irq_to_desc(irq);
207 spin_lock_irqsave(&desc->lock, flags);
208 if (!desc->depth++) {
209 desc->status |= IRQ_DISABLED;
210 desc->chip->disable(irq);
212 spin_unlock_irqrestore(&desc->lock, flags);
214 EXPORT_SYMBOL(disable_irq_nosync);
217 * disable_irq - disable an irq and wait for completion
218 * @irq: Interrupt to disable
220 * Disable the selected interrupt line. Enables and Disables are
222 * This function waits for any pending IRQ handlers for this interrupt
223 * to complete before returning. If you use this function while
224 * holding a resource the IRQ handler may need you will deadlock.
226 * This function may be called - with care - from IRQ context.
228 void disable_irq(unsigned int irq)
230 struct irq_desc *desc = irq_to_desc(irq);
235 disable_irq_nosync(irq);
237 synchronize_irq(irq);
239 EXPORT_SYMBOL(disable_irq);
241 static void __enable_irq(struct irq_desc *desc, unsigned int irq)
243 switch (desc->depth) {
245 WARN(1, KERN_WARNING "Unbalanced enable for IRQ %d\n", irq);
248 unsigned int status = desc->status & ~IRQ_DISABLED;
250 /* Prevent probing on this irq: */
251 desc->status = status | IRQ_NOPROBE;
252 check_irq_resend(desc, irq);
261 * enable_irq - enable handling of an irq
262 * @irq: Interrupt to enable
264 * Undoes the effect of one call to disable_irq(). If this
265 * matches the last disable, processing of interrupts on this
266 * IRQ line is re-enabled.
268 * This function may be called from IRQ context.
270 void enable_irq(unsigned int irq)
272 struct irq_desc *desc = irq_to_desc(irq);
278 spin_lock_irqsave(&desc->lock, flags);
279 __enable_irq(desc, irq);
280 spin_unlock_irqrestore(&desc->lock, flags);
282 EXPORT_SYMBOL(enable_irq);
284 static int set_irq_wake_real(unsigned int irq, unsigned int on)
286 struct irq_desc *desc = irq_to_desc(irq);
289 if (desc->chip->set_wake)
290 ret = desc->chip->set_wake(irq, on);
296 * set_irq_wake - control irq power management wakeup
297 * @irq: interrupt to control
298 * @on: enable/disable power management wakeup
300 * Enable/disable power management wakeup mode, which is
301 * disabled by default. Enables and disables must match,
302 * just as they match for non-wakeup mode support.
304 * Wakeup mode lets this IRQ wake the system from sleep
305 * states like "suspend to RAM".
307 int set_irq_wake(unsigned int irq, unsigned int on)
309 struct irq_desc *desc = irq_to_desc(irq);
313 /* wakeup-capable irqs can be shared between drivers that
314 * don't need to have the same sleep mode behaviors.
316 spin_lock_irqsave(&desc->lock, flags);
318 if (desc->wake_depth++ == 0) {
319 ret = set_irq_wake_real(irq, on);
321 desc->wake_depth = 0;
323 desc->status |= IRQ_WAKEUP;
326 if (desc->wake_depth == 0) {
327 WARN(1, "Unbalanced IRQ %d wake disable\n", irq);
328 } else if (--desc->wake_depth == 0) {
329 ret = set_irq_wake_real(irq, on);
331 desc->wake_depth = 1;
333 desc->status &= ~IRQ_WAKEUP;
337 spin_unlock_irqrestore(&desc->lock, flags);
340 EXPORT_SYMBOL(set_irq_wake);
343 * Internal function that tells the architecture code whether a
344 * particular irq has been exclusively allocated or is available
347 int can_request_irq(unsigned int irq, unsigned long irqflags)
349 struct irq_desc *desc = irq_to_desc(irq);
350 struct irqaction *action;
355 if (desc->status & IRQ_NOREQUEST)
358 action = desc->action;
360 if (irqflags & action->flags & IRQF_SHARED)
366 void compat_irq_chip_set_default_handler(struct irq_desc *desc)
369 * If the architecture still has not overriden
370 * the flow handler then zap the default. This
371 * should catch incorrect flow-type setting.
373 if (desc->handle_irq == &handle_bad_irq)
374 desc->handle_irq = NULL;
377 int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
381 struct irq_chip *chip = desc->chip;
383 if (!chip || !chip->set_type) {
385 * IRQF_TRIGGER_* but the PIC does not support multiple
388 pr_debug("No set_type function for IRQ %d (%s)\n", irq,
389 chip ? (chip->name ? : "unknown") : "unknown");
393 /* caller masked out all except trigger mode flags */
394 ret = chip->set_type(irq, flags);
397 pr_err("setting trigger mode %d for irq %u failed (%pF)\n",
398 (int)flags, irq, chip->set_type);
400 if (flags & (IRQ_TYPE_LEVEL_LOW | IRQ_TYPE_LEVEL_HIGH))
402 /* note that IRQF_TRIGGER_MASK == IRQ_TYPE_SENSE_MASK */
403 desc->status &= ~(IRQ_LEVEL | IRQ_TYPE_SENSE_MASK);
404 desc->status |= flags;
410 static int irq_wait_for_interrupt(struct irqaction *action)
412 while (!kthread_should_stop()) {
413 set_current_state(TASK_INTERRUPTIBLE);
415 if (test_and_clear_bit(IRQTF_RUNTHREAD,
416 &action->thread_flags)) {
417 __set_current_state(TASK_RUNNING);
426 * Interrupt handler thread
428 static int irq_thread(void *data)
430 struct sched_param param = { .sched_priority = MAX_USER_RT_PRIO/2, };
431 struct irqaction *action = data;
432 struct irq_desc *desc = irq_to_desc(action->irq);
435 sched_setscheduler(current, SCHED_FIFO, ¶m);
436 current->irqaction = action;
438 while (!irq_wait_for_interrupt(action)) {
440 atomic_inc(&desc->threads_active);
442 spin_lock_irq(&desc->lock);
443 if (unlikely(desc->status & IRQ_DISABLED)) {
445 * CHECKME: We might need a dedicated
446 * IRQ_THREAD_PENDING flag here, which
447 * retriggers the thread in check_irq_resend()
448 * but AFAICT IRQ_PENDING should be fine as it
449 * retriggers the interrupt itself --- tglx
451 desc->status |= IRQ_PENDING;
452 spin_unlock_irq(&desc->lock);
454 spin_unlock_irq(&desc->lock);
456 action->thread_fn(action->irq, action->dev_id);
459 wake = atomic_dec_and_test(&desc->threads_active);
461 if (wake && waitqueue_active(&desc->wait_for_threads))
462 wake_up(&desc->wait_for_threads);
466 * Clear irqaction. Otherwise exit_irq_thread() would make
467 * fuzz about an active irq thread going into nirvana.
469 current->irqaction = NULL;
474 * Called from do_exit()
476 void exit_irq_thread(void)
478 struct task_struct *tsk = current;
484 "exiting task \"%s\" (%d) is an active IRQ thread (irq %d)\n",
485 tsk->comm ? tsk->comm : "", tsk->pid, tsk->irqaction->irq);
488 * Set the THREAD DIED flag to prevent further wakeups of the
489 * soon to be gone threaded handler.
491 set_bit(IRQTF_DIED, &tsk->irqaction->flags);
495 * Internal function to register an irqaction - typically used to
496 * allocate special interrupts that are part of the architecture.
499 __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
501 struct irqaction *old, **old_ptr;
502 const char *old_name = NULL;
510 if (desc->chip == &no_irq_chip)
513 * Some drivers like serial.c use request_irq() heavily,
514 * so we have to be careful not to interfere with a
517 if (new->flags & IRQF_SAMPLE_RANDOM) {
519 * This function might sleep, we want to call it first,
520 * outside of the atomic block.
521 * Yes, this might clear the entropy pool if the wrong
522 * driver is attempted to be loaded, without actually
523 * installing a new handler, but is this really a problem,
524 * only the sysadmin is able to do this.
526 rand_initialize_irq(irq);
532 if (new->thread_fn) {
533 struct task_struct *t;
535 t = kthread_create(irq_thread, new, "irq/%d-%s", irq,
540 * We keep the reference to the task struct even if
541 * the thread dies to avoid that the interrupt code
542 * references an already freed task_struct.
550 * The following block of code has to be executed atomically
552 spin_lock_irqsave(&desc->lock, flags);
553 old_ptr = &desc->action;
557 * Can't share interrupts unless both agree to and are
558 * the same type (level, edge, polarity). So both flag
559 * fields must have IRQF_SHARED set and the bits which
560 * set the trigger type must match.
562 if (!((old->flags & new->flags) & IRQF_SHARED) ||
563 ((old->flags ^ new->flags) & IRQF_TRIGGER_MASK)) {
564 old_name = old->name;
568 #if defined(CONFIG_IRQ_PER_CPU)
569 /* All handlers must agree on per-cpuness */
570 if ((old->flags & IRQF_PERCPU) !=
571 (new->flags & IRQF_PERCPU))
575 /* add new interrupt at end of irq queue */
577 old_ptr = &old->next;
584 irq_chip_set_defaults(desc->chip);
586 init_waitqueue_head(&desc->wait_for_threads);
588 /* Setup the type (level, edge polarity) if configured: */
589 if (new->flags & IRQF_TRIGGER_MASK) {
590 ret = __irq_set_trigger(desc, irq,
591 new->flags & IRQF_TRIGGER_MASK);
596 compat_irq_chip_set_default_handler(desc);
597 #if defined(CONFIG_IRQ_PER_CPU)
598 if (new->flags & IRQF_PERCPU)
599 desc->status |= IRQ_PER_CPU;
602 desc->status &= ~(IRQ_AUTODETECT | IRQ_WAITING |
603 IRQ_INPROGRESS | IRQ_SPURIOUS_DISABLED);
605 if (!(desc->status & IRQ_NOAUTOEN)) {
607 desc->status &= ~IRQ_DISABLED;
608 desc->chip->startup(irq);
610 /* Undo nested disables: */
613 /* Exclude IRQ from balancing if requested */
614 if (new->flags & IRQF_NOBALANCING)
615 desc->status |= IRQ_NO_BALANCING;
617 /* Set default affinity mask once everything is setup */
618 setup_affinity(irq, desc);
620 } else if ((new->flags & IRQF_TRIGGER_MASK)
621 && (new->flags & IRQF_TRIGGER_MASK)
622 != (desc->status & IRQ_TYPE_SENSE_MASK)) {
623 /* hope the handler works with the actual trigger mode... */
624 pr_warning("IRQ %d uses trigger mode %d; requested %d\n",
625 irq, (int)(desc->status & IRQ_TYPE_SENSE_MASK),
626 (int)(new->flags & IRQF_TRIGGER_MASK));
631 /* Reset broken irq detection when installing new handler */
633 desc->irqs_unhandled = 0;
636 * Check whether we disabled the irq via the spurious handler
637 * before. Reenable it and give it another chance.
639 if (shared && (desc->status & IRQ_SPURIOUS_DISABLED)) {
640 desc->status &= ~IRQ_SPURIOUS_DISABLED;
641 __enable_irq(desc, irq);
644 spin_unlock_irqrestore(&desc->lock, flags);
647 register_irq_proc(irq, desc);
649 register_handler_proc(irq, new);
654 #ifdef CONFIG_DEBUG_SHIRQ
655 if (!(new->flags & IRQF_PROBE_SHARED)) {
656 printk(KERN_ERR "IRQ handler type mismatch for IRQ %d\n", irq);
658 printk(KERN_ERR "current handler: %s\n", old_name);
665 spin_unlock_irqrestore(&desc->lock, flags);
667 struct task_struct *t = new->thread;
670 if (likely(!test_bit(IRQTF_DIED, &new->thread_flags)))
678 * setup_irq - setup an interrupt
679 * @irq: Interrupt line to setup
680 * @act: irqaction for the interrupt
682 * Used to statically setup interrupts in the early boot process.
684 int setup_irq(unsigned int irq, struct irqaction *act)
686 struct irq_desc *desc = irq_to_desc(irq);
688 return __setup_irq(irq, desc, act);
690 EXPORT_SYMBOL_GPL(setup_irq);
693 * Internal function to unregister an irqaction - used to free
694 * regular and special interrupts that are part of the architecture.
696 static struct irqaction *__free_irq(unsigned int irq, void *dev_id)
698 struct irq_desc *desc = irq_to_desc(irq);
699 struct irqaction *action, **action_ptr;
700 struct task_struct *irqthread;
703 WARN(in_interrupt(), "Trying to free IRQ %d from IRQ context!\n", irq);
708 spin_lock_irqsave(&desc->lock, flags);
711 * There can be multiple actions per IRQ descriptor, find the right
712 * one based on the dev_id:
714 action_ptr = &desc->action;
716 action = *action_ptr;
719 WARN(1, "Trying to free already-free IRQ %d\n", irq);
720 spin_unlock_irqrestore(&desc->lock, flags);
725 if (action->dev_id == dev_id)
727 action_ptr = &action->next;
730 /* Found it - now remove it from the list of entries: */
731 *action_ptr = action->next;
733 /* Currently used only by UML, might disappear one day: */
734 #ifdef CONFIG_IRQ_RELEASE_METHOD
735 if (desc->chip->release)
736 desc->chip->release(irq, dev_id);
739 /* If this was the last handler, shut down the IRQ line: */
741 desc->status |= IRQ_DISABLED;
742 if (desc->chip->shutdown)
743 desc->chip->shutdown(irq);
745 desc->chip->disable(irq);
748 irqthread = action->thread;
749 action->thread = NULL;
751 spin_unlock_irqrestore(&desc->lock, flags);
753 unregister_handler_proc(irq, action);
755 /* Make sure it's not being used on another CPU: */
756 synchronize_irq(irq);
759 if (!test_bit(IRQTF_DIED, &action->thread_flags))
760 kthread_stop(irqthread);
761 put_task_struct(irqthread);
764 #ifdef CONFIG_DEBUG_SHIRQ
766 * It's a shared IRQ -- the driver ought to be prepared for an IRQ
767 * event to happen even now it's being freed, so let's make sure that
768 * is so by doing an extra call to the handler ....
770 * ( We do this after actually deregistering it, to make sure that a
771 * 'real' IRQ doesn't run in * parallel with our fake. )
773 if (action->flags & IRQF_SHARED) {
774 local_irq_save(flags);
775 action->handler(irq, dev_id);
776 local_irq_restore(flags);
783 * remove_irq - free an interrupt
784 * @irq: Interrupt line to free
785 * @act: irqaction for the interrupt
787 * Used to remove interrupts statically setup by the early boot process.
789 void remove_irq(unsigned int irq, struct irqaction *act)
791 __free_irq(irq, act->dev_id);
793 EXPORT_SYMBOL_GPL(remove_irq);
796 * free_irq - free an interrupt allocated with request_irq
797 * @irq: Interrupt line to free
798 * @dev_id: Device identity to free
800 * Remove an interrupt handler. The handler is removed and if the
801 * interrupt line is no longer in use by any driver it is disabled.
802 * On a shared IRQ the caller must ensure the interrupt is disabled
803 * on the card it drives before calling this function. The function
804 * does not return until any executing interrupts for this IRQ
807 * This function must not be called from interrupt context.
809 void free_irq(unsigned int irq, void *dev_id)
811 kfree(__free_irq(irq, dev_id));
813 EXPORT_SYMBOL(free_irq);
816 * request_threaded_irq - allocate an interrupt line
817 * @irq: Interrupt line to allocate
818 * @handler: Function to be called when the IRQ occurs.
819 * Primary handler for threaded interrupts
820 * @thread_fn: Function called from the irq handler thread
821 * If NULL, no irq thread is created
822 * @irqflags: Interrupt type flags
823 * @devname: An ascii name for the claiming device
824 * @dev_id: A cookie passed back to the handler function
826 * This call allocates interrupt resources and enables the
827 * interrupt line and IRQ handling. From the point this
828 * call is made your handler function may be invoked. Since
829 * your handler function must clear any interrupt the board
830 * raises, you must take care both to initialise your hardware
831 * and to set up the interrupt handler in the right order.
833 * If you want to set up a threaded irq handler for your device
834 * then you need to supply @handler and @thread_fn. @handler ist
835 * still called in hard interrupt context and has to check
836 * whether the interrupt originates from the device. If yes it
837 * needs to disable the interrupt on the device and return
838 * IRQ_THREAD_WAKE which will wake up the handler thread and run
839 * @thread_fn. This split handler design is necessary to support
842 * Dev_id must be globally unique. Normally the address of the
843 * device data structure is used as the cookie. Since the handler
844 * receives this value it makes sense to use it.
846 * If your interrupt is shared you must pass a non NULL dev_id
847 * as this is required when freeing the interrupt.
851 * IRQF_SHARED Interrupt is shared
852 * IRQF_DISABLED Disable local interrupts while processing
853 * IRQF_SAMPLE_RANDOM The interrupt can be used for entropy
854 * IRQF_TRIGGER_* Specify active edge(s) or level
857 int request_threaded_irq(unsigned int irq, irq_handler_t handler,
858 irq_handler_t thread_fn, unsigned long irqflags,
859 const char *devname, void *dev_id)
861 struct irqaction *action;
862 struct irq_desc *desc;
866 * handle_IRQ_event() always ignores IRQF_DISABLED except for
867 * the _first_ irqaction (sigh). That can cause oopsing, but
868 * the behavior is classified as "will not fix" so we need to
869 * start nudging drivers away from using that idiom.
871 if ((irqflags & (IRQF_SHARED|IRQF_DISABLED)) ==
872 (IRQF_SHARED|IRQF_DISABLED)) {
874 "IRQ %d/%s: IRQF_DISABLED is not guaranteed on shared IRQs\n",
878 #ifdef CONFIG_LOCKDEP
880 * Lockdep wants atomic interrupt handlers:
882 irqflags |= IRQF_DISABLED;
885 * Sanity-check: shared interrupts must pass in a real dev-ID,
886 * otherwise we'll have trouble later trying to figure out
887 * which interrupt is which (messes up the interrupt freeing
890 if ((irqflags & IRQF_SHARED) && !dev_id)
893 desc = irq_to_desc(irq);
897 if (desc->status & IRQ_NOREQUEST)
902 action = kzalloc(sizeof(struct irqaction), GFP_KERNEL);
906 action->handler = handler;
907 action->thread_fn = thread_fn;
908 action->flags = irqflags;
909 action->name = devname;
910 action->dev_id = dev_id;
912 retval = __setup_irq(irq, desc, action);
916 #ifdef CONFIG_DEBUG_SHIRQ
917 if (irqflags & IRQF_SHARED) {
919 * It's a shared IRQ -- the driver ought to be prepared for it
920 * to happen immediately, so let's make sure....
921 * We disable the irq to make sure that a 'real' IRQ doesn't
922 * run in parallel with our fake.
927 local_irq_save(flags);
929 handler(irq, dev_id);
931 local_irq_restore(flags);
937 EXPORT_SYMBOL(request_threaded_irq);