Merge branch 'for-linus' of git://repo.or.cz/cris-mirror
[kernel.git] / kernel / irq / manage.c
1 /*
2  * linux/kernel/irq/manage.c
3  *
4  * Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
5  * Copyright (C) 2005-2006 Thomas Gleixner
6  *
7  * This file contains driver APIs to the irq subsystem.
8  */
9
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>
17
18 #include "internals.h"
19
20 /**
21  *      synchronize_irq - wait for pending IRQ handlers (on other CPUs)
22  *      @irq: interrupt number to wait for
23  *
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.
27  *
28  *      This function may be called - with care - from IRQ context.
29  */
30 void synchronize_irq(unsigned int irq)
31 {
32         struct irq_desc *desc = irq_to_desc(irq);
33         unsigned int status;
34
35         if (!desc)
36                 return;
37
38         do {
39                 unsigned long flags;
40
41                 /*
42                  * Wait until we're out of the critical section.  This might
43                  * give the wrong answer due to the lack of memory barriers.
44                  */
45                 while (desc->status & IRQ_INPROGRESS)
46                         cpu_relax();
47
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);
52
53                 /* Oops, that failed? */
54         } while (status & IRQ_INPROGRESS);
55
56         /*
57          * We made sure that no hardirq handler is running. Now verify
58          * that no threaded handlers are active.
59          */
60         wait_event(desc->wait_for_threads, !atomic_read(&desc->threads_active));
61 }
62 EXPORT_SYMBOL(synchronize_irq);
63
64 #ifdef CONFIG_SMP
65 cpumask_var_t irq_default_affinity;
66
67 /**
68  *      irq_can_set_affinity - Check if the affinity of a given irq can be set
69  *      @irq:           Interrupt to check
70  *
71  */
72 int irq_can_set_affinity(unsigned int irq)
73 {
74         struct irq_desc *desc = irq_to_desc(irq);
75
76         if (CHECK_IRQ_PER_CPU(desc->status) || !desc->chip ||
77             !desc->chip->set_affinity)
78                 return 0;
79
80         return 1;
81 }
82
83 static void
84 irq_set_thread_affinity(struct irq_desc *desc, const struct cpumask *cpumask)
85 {
86         struct irqaction *action = desc->action;
87
88         while (action) {
89                 if (action->thread)
90                         set_cpus_allowed_ptr(action->thread, cpumask);
91                 action = action->next;
92         }
93 }
94
95 /**
96  *      irq_set_affinity - Set the irq affinity of a given irq
97  *      @irq:           Interrupt to set affinity
98  *      @cpumask:       cpumask
99  *
100  */
101 int irq_set_affinity(unsigned int irq, const struct cpumask *cpumask)
102 {
103         struct irq_desc *desc = irq_to_desc(irq);
104         unsigned long flags;
105
106         if (!desc->chip->set_affinity)
107                 return -EINVAL;
108
109         spin_lock_irqsave(&desc->lock, flags);
110
111 #ifdef CONFIG_GENERIC_PENDING_IRQ
112         if (desc->status & IRQ_MOVE_PCNTXT)
113                 desc->chip->set_affinity(irq, cpumask);
114         else {
115                 desc->status |= IRQ_MOVE_PENDING;
116                 cpumask_copy(desc->pending_mask, cpumask);
117         }
118 #else
119         cpumask_copy(desc->affinity, cpumask);
120         desc->chip->set_affinity(irq, cpumask);
121 #endif
122         irq_set_thread_affinity(desc, cpumask);
123         desc->status |= IRQ_AFFINITY_SET;
124         spin_unlock_irqrestore(&desc->lock, flags);
125         return 0;
126 }
127
128 #ifndef CONFIG_AUTO_IRQ_AFFINITY
129 /*
130  * Generic version of the affinity autoselector.
131  */
132 static int setup_affinity(unsigned int irq, struct irq_desc *desc)
133 {
134         if (!irq_can_set_affinity(irq))
135                 return 0;
136
137         /*
138          * Preserve an userspace affinity setup, but make sure that
139          * one of the targets is online.
140          */
141         if (desc->status & (IRQ_AFFINITY_SET | IRQ_NO_BALANCING)) {
142                 if (cpumask_any_and(desc->affinity, cpu_online_mask)
143                     < nr_cpu_ids)
144                         goto set_affinity;
145                 else
146                         desc->status &= ~IRQ_AFFINITY_SET;
147         }
148
149         cpumask_and(desc->affinity, cpu_online_mask, irq_default_affinity);
150 set_affinity:
151         desc->chip->set_affinity(irq, desc->affinity);
152
153         return 0;
154 }
155 #else
156 static inline int setup_affinity(unsigned int irq, struct irq_desc *d)
157 {
158         return irq_select_affinity(irq);
159 }
160 #endif
161
162 /*
163  * Called when affinity is set via /proc/irq
164  */
165 int irq_select_affinity_usr(unsigned int irq)
166 {
167         struct irq_desc *desc = irq_to_desc(irq);
168         unsigned long flags;
169         int ret;
170
171         spin_lock_irqsave(&desc->lock, flags);
172         ret = setup_affinity(irq, desc);
173         if (!ret)
174                 irq_set_thread_affinity(desc, desc->affinity);
175         spin_unlock_irqrestore(&desc->lock, flags);
176
177         return ret;
178 }
179
180 #else
181 static inline int setup_affinity(unsigned int irq, struct irq_desc *desc)
182 {
183         return 0;
184 }
185 #endif
186
187 void __disable_irq(struct irq_desc *desc, unsigned int irq, bool suspend)
188 {
189         if (suspend) {
190                 if (!desc->action || (desc->action->flags & IRQF_TIMER))
191                         return;
192                 desc->status |= IRQ_SUSPENDED;
193         }
194
195         if (!desc->depth++) {
196                 desc->status |= IRQ_DISABLED;
197                 desc->chip->disable(irq);
198         }
199 }
200
201 /**
202  *      disable_irq_nosync - disable an irq without waiting
203  *      @irq: Interrupt to disable
204  *
205  *      Disable the selected interrupt line.  Disables and Enables are
206  *      nested.
207  *      Unlike disable_irq(), this function does not ensure existing
208  *      instances of the IRQ handler have completed before returning.
209  *
210  *      This function may be called from IRQ context.
211  */
212 void disable_irq_nosync(unsigned int irq)
213 {
214         struct irq_desc *desc = irq_to_desc(irq);
215         unsigned long flags;
216
217         if (!desc)
218                 return;
219
220         spin_lock_irqsave(&desc->lock, flags);
221         __disable_irq(desc, irq, false);
222         spin_unlock_irqrestore(&desc->lock, flags);
223 }
224 EXPORT_SYMBOL(disable_irq_nosync);
225
226 /**
227  *      disable_irq - disable an irq and wait for completion
228  *      @irq: Interrupt to disable
229  *
230  *      Disable the selected interrupt line.  Enables and Disables are
231  *      nested.
232  *      This function waits for any pending IRQ handlers for this interrupt
233  *      to complete before returning. If you use this function while
234  *      holding a resource the IRQ handler may need you will deadlock.
235  *
236  *      This function may be called - with care - from IRQ context.
237  */
238 void disable_irq(unsigned int irq)
239 {
240         struct irq_desc *desc = irq_to_desc(irq);
241
242         if (!desc)
243                 return;
244
245         disable_irq_nosync(irq);
246         if (desc->action)
247                 synchronize_irq(irq);
248 }
249 EXPORT_SYMBOL(disable_irq);
250
251 void __enable_irq(struct irq_desc *desc, unsigned int irq, bool resume)
252 {
253         if (resume)
254                 desc->status &= ~IRQ_SUSPENDED;
255
256         switch (desc->depth) {
257         case 0:
258  err_out:
259                 WARN(1, KERN_WARNING "Unbalanced enable for IRQ %d\n", irq);
260                 break;
261         case 1: {
262                 unsigned int status = desc->status & ~IRQ_DISABLED;
263
264                 if (desc->status & IRQ_SUSPENDED)
265                         goto err_out;
266                 /* Prevent probing on this irq: */
267                 desc->status = status | IRQ_NOPROBE;
268                 check_irq_resend(desc, irq);
269                 /* fall-through */
270         }
271         default:
272                 desc->depth--;
273         }
274 }
275
276 /**
277  *      enable_irq - enable handling of an irq
278  *      @irq: Interrupt to enable
279  *
280  *      Undoes the effect of one call to disable_irq().  If this
281  *      matches the last disable, processing of interrupts on this
282  *      IRQ line is re-enabled.
283  *
284  *      This function may be called from IRQ context.
285  */
286 void enable_irq(unsigned int irq)
287 {
288         struct irq_desc *desc = irq_to_desc(irq);
289         unsigned long flags;
290
291         if (!desc)
292                 return;
293
294         spin_lock_irqsave(&desc->lock, flags);
295         __enable_irq(desc, irq, false);
296         spin_unlock_irqrestore(&desc->lock, flags);
297 }
298 EXPORT_SYMBOL(enable_irq);
299
300 static int set_irq_wake_real(unsigned int irq, unsigned int on)
301 {
302         struct irq_desc *desc = irq_to_desc(irq);
303         int ret = -ENXIO;
304
305         if (desc->chip->set_wake)
306                 ret = desc->chip->set_wake(irq, on);
307
308         return ret;
309 }
310
311 /**
312  *      set_irq_wake - control irq power management wakeup
313  *      @irq:   interrupt to control
314  *      @on:    enable/disable power management wakeup
315  *
316  *      Enable/disable power management wakeup mode, which is
317  *      disabled by default.  Enables and disables must match,
318  *      just as they match for non-wakeup mode support.
319  *
320  *      Wakeup mode lets this IRQ wake the system from sleep
321  *      states like "suspend to RAM".
322  */
323 int set_irq_wake(unsigned int irq, unsigned int on)
324 {
325         struct irq_desc *desc = irq_to_desc(irq);
326         unsigned long flags;
327         int ret = 0;
328
329         /* wakeup-capable irqs can be shared between drivers that
330          * don't need to have the same sleep mode behaviors.
331          */
332         spin_lock_irqsave(&desc->lock, flags);
333         if (on) {
334                 if (desc->wake_depth++ == 0) {
335                         ret = set_irq_wake_real(irq, on);
336                         if (ret)
337                                 desc->wake_depth = 0;
338                         else
339                                 desc->status |= IRQ_WAKEUP;
340                 }
341         } else {
342                 if (desc->wake_depth == 0) {
343                         WARN(1, "Unbalanced IRQ %d wake disable\n", irq);
344                 } else if (--desc->wake_depth == 0) {
345                         ret = set_irq_wake_real(irq, on);
346                         if (ret)
347                                 desc->wake_depth = 1;
348                         else
349                                 desc->status &= ~IRQ_WAKEUP;
350                 }
351         }
352
353         spin_unlock_irqrestore(&desc->lock, flags);
354         return ret;
355 }
356 EXPORT_SYMBOL(set_irq_wake);
357
358 /*
359  * Internal function that tells the architecture code whether a
360  * particular irq has been exclusively allocated or is available
361  * for driver use.
362  */
363 int can_request_irq(unsigned int irq, unsigned long irqflags)
364 {
365         struct irq_desc *desc = irq_to_desc(irq);
366         struct irqaction *action;
367
368         if (!desc)
369                 return 0;
370
371         if (desc->status & IRQ_NOREQUEST)
372                 return 0;
373
374         action = desc->action;
375         if (action)
376                 if (irqflags & action->flags & IRQF_SHARED)
377                         action = NULL;
378
379         return !action;
380 }
381
382 void compat_irq_chip_set_default_handler(struct irq_desc *desc)
383 {
384         /*
385          * If the architecture still has not overriden
386          * the flow handler then zap the default. This
387          * should catch incorrect flow-type setting.
388          */
389         if (desc->handle_irq == &handle_bad_irq)
390                 desc->handle_irq = NULL;
391 }
392
393 int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
394                 unsigned long flags)
395 {
396         int ret;
397         struct irq_chip *chip = desc->chip;
398
399         if (!chip || !chip->set_type) {
400                 /*
401                  * IRQF_TRIGGER_* but the PIC does not support multiple
402                  * flow-types?
403                  */
404                 pr_debug("No set_type function for IRQ %d (%s)\n", irq,
405                                 chip ? (chip->name ? : "unknown") : "unknown");
406                 return 0;
407         }
408
409         /* caller masked out all except trigger mode flags */
410         ret = chip->set_type(irq, flags);
411
412         if (ret)
413                 pr_err("setting trigger mode %d for irq %u failed (%pF)\n",
414                                 (int)flags, irq, chip->set_type);
415         else {
416                 if (flags & (IRQ_TYPE_LEVEL_LOW | IRQ_TYPE_LEVEL_HIGH))
417                         flags |= IRQ_LEVEL;
418                 /* note that IRQF_TRIGGER_MASK == IRQ_TYPE_SENSE_MASK */
419                 desc->status &= ~(IRQ_LEVEL | IRQ_TYPE_SENSE_MASK);
420                 desc->status |= flags;
421         }
422
423         return ret;
424 }
425
426 static int irq_wait_for_interrupt(struct irqaction *action)
427 {
428         while (!kthread_should_stop()) {
429                 set_current_state(TASK_INTERRUPTIBLE);
430
431                 if (test_and_clear_bit(IRQTF_RUNTHREAD,
432                                        &action->thread_flags)) {
433                         __set_current_state(TASK_RUNNING);
434                         return 0;
435                 }
436                 schedule();
437         }
438         return -1;
439 }
440
441 /*
442  * Interrupt handler thread
443  */
444 static int irq_thread(void *data)
445 {
446         struct sched_param param = { .sched_priority = MAX_USER_RT_PRIO/2, };
447         struct irqaction *action = data;
448         struct irq_desc *desc = irq_to_desc(action->irq);
449         int wake;
450
451         sched_setscheduler(current, SCHED_FIFO, &param);
452         current->irqaction = action;
453
454         while (!irq_wait_for_interrupt(action)) {
455
456                 atomic_inc(&desc->threads_active);
457
458                 spin_lock_irq(&desc->lock);
459                 if (unlikely(desc->status & IRQ_DISABLED)) {
460                         /*
461                          * CHECKME: We might need a dedicated
462                          * IRQ_THREAD_PENDING flag here, which
463                          * retriggers the thread in check_irq_resend()
464                          * but AFAICT IRQ_PENDING should be fine as it
465                          * retriggers the interrupt itself --- tglx
466                          */
467                         desc->status |= IRQ_PENDING;
468                         spin_unlock_irq(&desc->lock);
469                 } else {
470                         spin_unlock_irq(&desc->lock);
471
472                         action->thread_fn(action->irq, action->dev_id);
473                 }
474
475                 wake = atomic_dec_and_test(&desc->threads_active);
476
477                 if (wake && waitqueue_active(&desc->wait_for_threads))
478                         wake_up(&desc->wait_for_threads);
479         }
480
481         /*
482          * Clear irqaction. Otherwise exit_irq_thread() would make
483          * fuzz about an active irq thread going into nirvana.
484          */
485         current->irqaction = NULL;
486         return 0;
487 }
488
489 /*
490  * Called from do_exit()
491  */
492 void exit_irq_thread(void)
493 {
494         struct task_struct *tsk = current;
495
496         if (!tsk->irqaction)
497                 return;
498
499         printk(KERN_ERR
500                "exiting task \"%s\" (%d) is an active IRQ thread (irq %d)\n",
501                tsk->comm ? tsk->comm : "", tsk->pid, tsk->irqaction->irq);
502
503         /*
504          * Set the THREAD DIED flag to prevent further wakeups of the
505          * soon to be gone threaded handler.
506          */
507         set_bit(IRQTF_DIED, &tsk->irqaction->flags);
508 }
509
510 /*
511  * Internal function to register an irqaction - typically used to
512  * allocate special interrupts that are part of the architecture.
513  */
514 static int
515 __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
516 {
517         struct irqaction *old, **old_ptr;
518         const char *old_name = NULL;
519         unsigned long flags;
520         int shared = 0;
521         int ret;
522
523         if (!desc)
524                 return -EINVAL;
525
526         if (desc->chip == &no_irq_chip)
527                 return -ENOSYS;
528         /*
529          * Some drivers like serial.c use request_irq() heavily,
530          * so we have to be careful not to interfere with a
531          * running system.
532          */
533         if (new->flags & IRQF_SAMPLE_RANDOM) {
534                 /*
535                  * This function might sleep, we want to call it first,
536                  * outside of the atomic block.
537                  * Yes, this might clear the entropy pool if the wrong
538                  * driver is attempted to be loaded, without actually
539                  * installing a new handler, but is this really a problem,
540                  * only the sysadmin is able to do this.
541                  */
542                 rand_initialize_irq(irq);
543         }
544
545         /*
546          * Threaded handler ?
547          */
548         if (new->thread_fn) {
549                 struct task_struct *t;
550
551                 t = kthread_create(irq_thread, new, "irq/%d-%s", irq,
552                                    new->name);
553                 if (IS_ERR(t))
554                         return PTR_ERR(t);
555                 /*
556                  * We keep the reference to the task struct even if
557                  * the thread dies to avoid that the interrupt code
558                  * references an already freed task_struct.
559                  */
560                 get_task_struct(t);
561                 new->thread = t;
562                 wake_up_process(t);
563         }
564
565         /*
566          * The following block of code has to be executed atomically
567          */
568         spin_lock_irqsave(&desc->lock, flags);
569         old_ptr = &desc->action;
570         old = *old_ptr;
571         if (old) {
572                 /*
573                  * Can't share interrupts unless both agree to and are
574                  * the same type (level, edge, polarity). So both flag
575                  * fields must have IRQF_SHARED set and the bits which
576                  * set the trigger type must match.
577                  */
578                 if (!((old->flags & new->flags) & IRQF_SHARED) ||
579                     ((old->flags ^ new->flags) & IRQF_TRIGGER_MASK)) {
580                         old_name = old->name;
581                         goto mismatch;
582                 }
583
584 #if defined(CONFIG_IRQ_PER_CPU)
585                 /* All handlers must agree on per-cpuness */
586                 if ((old->flags & IRQF_PERCPU) !=
587                     (new->flags & IRQF_PERCPU))
588                         goto mismatch;
589 #endif
590
591                 /* add new interrupt at end of irq queue */
592                 do {
593                         old_ptr = &old->next;
594                         old = *old_ptr;
595                 } while (old);
596                 shared = 1;
597         }
598
599         if (!shared) {
600                 irq_chip_set_defaults(desc->chip);
601
602                 init_waitqueue_head(&desc->wait_for_threads);
603
604                 /* Setup the type (level, edge polarity) if configured: */
605                 if (new->flags & IRQF_TRIGGER_MASK) {
606                         ret = __irq_set_trigger(desc, irq,
607                                         new->flags & IRQF_TRIGGER_MASK);
608
609                         if (ret)
610                                 goto out_thread;
611                 } else
612                         compat_irq_chip_set_default_handler(desc);
613 #if defined(CONFIG_IRQ_PER_CPU)
614                 if (new->flags & IRQF_PERCPU)
615                         desc->status |= IRQ_PER_CPU;
616 #endif
617
618                 desc->status &= ~(IRQ_AUTODETECT | IRQ_WAITING |
619                                   IRQ_INPROGRESS | IRQ_SPURIOUS_DISABLED);
620
621                 if (!(desc->status & IRQ_NOAUTOEN)) {
622                         desc->depth = 0;
623                         desc->status &= ~IRQ_DISABLED;
624                         desc->chip->startup(irq);
625                 } else
626                         /* Undo nested disables: */
627                         desc->depth = 1;
628
629                 /* Exclude IRQ from balancing if requested */
630                 if (new->flags & IRQF_NOBALANCING)
631                         desc->status |= IRQ_NO_BALANCING;
632
633                 /* Set default affinity mask once everything is setup */
634                 setup_affinity(irq, desc);
635
636         } else if ((new->flags & IRQF_TRIGGER_MASK)
637                         && (new->flags & IRQF_TRIGGER_MASK)
638                                 != (desc->status & IRQ_TYPE_SENSE_MASK)) {
639                 /* hope the handler works with the actual trigger mode... */
640                 pr_warning("IRQ %d uses trigger mode %d; requested %d\n",
641                                 irq, (int)(desc->status & IRQ_TYPE_SENSE_MASK),
642                                 (int)(new->flags & IRQF_TRIGGER_MASK));
643         }
644
645         *old_ptr = new;
646
647         /* Reset broken irq detection when installing new handler */
648         desc->irq_count = 0;
649         desc->irqs_unhandled = 0;
650
651         /*
652          * Check whether we disabled the irq via the spurious handler
653          * before. Reenable it and give it another chance.
654          */
655         if (shared && (desc->status & IRQ_SPURIOUS_DISABLED)) {
656                 desc->status &= ~IRQ_SPURIOUS_DISABLED;
657                 __enable_irq(desc, irq, false);
658         }
659
660         spin_unlock_irqrestore(&desc->lock, flags);
661
662         new->irq = irq;
663         register_irq_proc(irq, desc);
664         new->dir = NULL;
665         register_handler_proc(irq, new);
666
667         return 0;
668
669 mismatch:
670 #ifdef CONFIG_DEBUG_SHIRQ
671         if (!(new->flags & IRQF_PROBE_SHARED)) {
672                 printk(KERN_ERR "IRQ handler type mismatch for IRQ %d\n", irq);
673                 if (old_name)
674                         printk(KERN_ERR "current handler: %s\n", old_name);
675                 dump_stack();
676         }
677 #endif
678         ret = -EBUSY;
679
680 out_thread:
681         spin_unlock_irqrestore(&desc->lock, flags);
682         if (new->thread) {
683                 struct task_struct *t = new->thread;
684
685                 new->thread = NULL;
686                 if (likely(!test_bit(IRQTF_DIED, &new->thread_flags)))
687                         kthread_stop(t);
688                 put_task_struct(t);
689         }
690         return ret;
691 }
692
693 /**
694  *      setup_irq - setup an interrupt
695  *      @irq: Interrupt line to setup
696  *      @act: irqaction for the interrupt
697  *
698  * Used to statically setup interrupts in the early boot process.
699  */
700 int setup_irq(unsigned int irq, struct irqaction *act)
701 {
702         struct irq_desc *desc = irq_to_desc(irq);
703
704         return __setup_irq(irq, desc, act);
705 }
706 EXPORT_SYMBOL_GPL(setup_irq);
707
708  /*
709  * Internal function to unregister an irqaction - used to free
710  * regular and special interrupts that are part of the architecture.
711  */
712 static struct irqaction *__free_irq(unsigned int irq, void *dev_id)
713 {
714         struct irq_desc *desc = irq_to_desc(irq);
715         struct irqaction *action, **action_ptr;
716         struct task_struct *irqthread;
717         unsigned long flags;
718
719         WARN(in_interrupt(), "Trying to free IRQ %d from IRQ context!\n", irq);
720
721         if (!desc)
722                 return NULL;
723
724         spin_lock_irqsave(&desc->lock, flags);
725
726         /*
727          * There can be multiple actions per IRQ descriptor, find the right
728          * one based on the dev_id:
729          */
730         action_ptr = &desc->action;
731         for (;;) {
732                 action = *action_ptr;
733
734                 if (!action) {
735                         WARN(1, "Trying to free already-free IRQ %d\n", irq);
736                         spin_unlock_irqrestore(&desc->lock, flags);
737
738                         return NULL;
739                 }
740
741                 if (action->dev_id == dev_id)
742                         break;
743                 action_ptr = &action->next;
744         }
745
746         /* Found it - now remove it from the list of entries: */
747         *action_ptr = action->next;
748
749         /* Currently used only by UML, might disappear one day: */
750 #ifdef CONFIG_IRQ_RELEASE_METHOD
751         if (desc->chip->release)
752                 desc->chip->release(irq, dev_id);
753 #endif
754
755         /* If this was the last handler, shut down the IRQ line: */
756         if (!desc->action) {
757                 desc->status |= IRQ_DISABLED;
758                 if (desc->chip->shutdown)
759                         desc->chip->shutdown(irq);
760                 else
761                         desc->chip->disable(irq);
762         }
763
764         irqthread = action->thread;
765         action->thread = NULL;
766
767         spin_unlock_irqrestore(&desc->lock, flags);
768
769         unregister_handler_proc(irq, action);
770
771         /* Make sure it's not being used on another CPU: */
772         synchronize_irq(irq);
773
774         if (irqthread) {
775                 if (!test_bit(IRQTF_DIED, &action->thread_flags))
776                         kthread_stop(irqthread);
777                 put_task_struct(irqthread);
778         }
779
780 #ifdef CONFIG_DEBUG_SHIRQ
781         /*
782          * It's a shared IRQ -- the driver ought to be prepared for an IRQ
783          * event to happen even now it's being freed, so let's make sure that
784          * is so by doing an extra call to the handler ....
785          *
786          * ( We do this after actually deregistering it, to make sure that a
787          *   'real' IRQ doesn't run in * parallel with our fake. )
788          */
789         if (action->flags & IRQF_SHARED) {
790                 local_irq_save(flags);
791                 action->handler(irq, dev_id);
792                 local_irq_restore(flags);
793         }
794 #endif
795         return action;
796 }
797
798 /**
799  *      remove_irq - free an interrupt
800  *      @irq: Interrupt line to free
801  *      @act: irqaction for the interrupt
802  *
803  * Used to remove interrupts statically setup by the early boot process.
804  */
805 void remove_irq(unsigned int irq, struct irqaction *act)
806 {
807         __free_irq(irq, act->dev_id);
808 }
809 EXPORT_SYMBOL_GPL(remove_irq);
810
811 /**
812  *      free_irq - free an interrupt allocated with request_irq
813  *      @irq: Interrupt line to free
814  *      @dev_id: Device identity to free
815  *
816  *      Remove an interrupt handler. The handler is removed and if the
817  *      interrupt line is no longer in use by any driver it is disabled.
818  *      On a shared IRQ the caller must ensure the interrupt is disabled
819  *      on the card it drives before calling this function. The function
820  *      does not return until any executing interrupts for this IRQ
821  *      have completed.
822  *
823  *      This function must not be called from interrupt context.
824  */
825 void free_irq(unsigned int irq, void *dev_id)
826 {
827         kfree(__free_irq(irq, dev_id));
828 }
829 EXPORT_SYMBOL(free_irq);
830
831 /**
832  *      request_threaded_irq - allocate an interrupt line
833  *      @irq: Interrupt line to allocate
834  *      @handler: Function to be called when the IRQ occurs.
835  *                Primary handler for threaded interrupts
836  *      @thread_fn: Function called from the irq handler thread
837  *                  If NULL, no irq thread is created
838  *      @irqflags: Interrupt type flags
839  *      @devname: An ascii name for the claiming device
840  *      @dev_id: A cookie passed back to the handler function
841  *
842  *      This call allocates interrupt resources and enables the
843  *      interrupt line and IRQ handling. From the point this
844  *      call is made your handler function may be invoked. Since
845  *      your handler function must clear any interrupt the board
846  *      raises, you must take care both to initialise your hardware
847  *      and to set up the interrupt handler in the right order.
848  *
849  *      If you want to set up a threaded irq handler for your device
850  *      then you need to supply @handler and @thread_fn. @handler ist
851  *      still called in hard interrupt context and has to check
852  *      whether the interrupt originates from the device. If yes it
853  *      needs to disable the interrupt on the device and return
854  *      IRQ_THREAD_WAKE which will wake up the handler thread and run
855  *      @thread_fn. This split handler design is necessary to support
856  *      shared interrupts.
857  *
858  *      Dev_id must be globally unique. Normally the address of the
859  *      device data structure is used as the cookie. Since the handler
860  *      receives this value it makes sense to use it.
861  *
862  *      If your interrupt is shared you must pass a non NULL dev_id
863  *      as this is required when freeing the interrupt.
864  *
865  *      Flags:
866  *
867  *      IRQF_SHARED             Interrupt is shared
868  *      IRQF_DISABLED   Disable local interrupts while processing
869  *      IRQF_SAMPLE_RANDOM      The interrupt can be used for entropy
870  *      IRQF_TRIGGER_*          Specify active edge(s) or level
871  *
872  */
873 int request_threaded_irq(unsigned int irq, irq_handler_t handler,
874                          irq_handler_t thread_fn, unsigned long irqflags,
875                          const char *devname, void *dev_id)
876 {
877         struct irqaction *action;
878         struct irq_desc *desc;
879         int retval;
880
881         /*
882          * handle_IRQ_event() always ignores IRQF_DISABLED except for
883          * the _first_ irqaction (sigh).  That can cause oopsing, but
884          * the behavior is classified as "will not fix" so we need to
885          * start nudging drivers away from using that idiom.
886          */
887         if ((irqflags & (IRQF_SHARED|IRQF_DISABLED)) ==
888                                         (IRQF_SHARED|IRQF_DISABLED)) {
889                 pr_warning(
890                   "IRQ %d/%s: IRQF_DISABLED is not guaranteed on shared IRQs\n",
891                         irq, devname);
892         }
893
894 #ifdef CONFIG_LOCKDEP
895         /*
896          * Lockdep wants atomic interrupt handlers:
897          */
898         irqflags |= IRQF_DISABLED;
899 #endif
900         /*
901          * Sanity-check: shared interrupts must pass in a real dev-ID,
902          * otherwise we'll have trouble later trying to figure out
903          * which interrupt is which (messes up the interrupt freeing
904          * logic etc).
905          */
906         if ((irqflags & IRQF_SHARED) && !dev_id)
907                 return -EINVAL;
908
909         desc = irq_to_desc(irq);
910         if (!desc)
911                 return -EINVAL;
912
913         if (desc->status & IRQ_NOREQUEST)
914                 return -EINVAL;
915         if (!handler)
916                 return -EINVAL;
917
918         action = kzalloc(sizeof(struct irqaction), GFP_KERNEL);
919         if (!action)
920                 return -ENOMEM;
921
922         action->handler = handler;
923         action->thread_fn = thread_fn;
924         action->flags = irqflags;
925         action->name = devname;
926         action->dev_id = dev_id;
927
928         retval = __setup_irq(irq, desc, action);
929         if (retval)
930                 kfree(action);
931
932 #ifdef CONFIG_DEBUG_SHIRQ
933         if (irqflags & IRQF_SHARED) {
934                 /*
935                  * It's a shared IRQ -- the driver ought to be prepared for it
936                  * to happen immediately, so let's make sure....
937                  * We disable the irq to make sure that a 'real' IRQ doesn't
938                  * run in parallel with our fake.
939                  */
940                 unsigned long flags;
941
942                 disable_irq(irq);
943                 local_irq_save(flags);
944
945                 handler(irq, dev_id);
946
947                 local_irq_restore(flags);
948                 enable_irq(irq);
949         }
950 #endif
951         return retval;
952 }
953 EXPORT_SYMBOL(request_threaded_irq);