genirq: do not execute DEBUG_SHIRQ when irq setup failed
[linux-2.6.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/module.h>
12 #include <linux/random.h>
13 #include <linux/interrupt.h>
14 #include <linux/slab.h>
15
16 #include "internals.h"
17
18 #if defined(CONFIG_SMP) && defined(CONFIG_GENERIC_HARDIRQS)
19 cpumask_var_t irq_default_affinity;
20
21 /**
22  *      synchronize_irq - wait for pending IRQ handlers (on other CPUs)
23  *      @irq: interrupt number to wait for
24  *
25  *      This function waits for any pending IRQ handlers for this interrupt
26  *      to complete before returning. If you use this function while
27  *      holding a resource the IRQ handler may need you will deadlock.
28  *
29  *      This function may be called - with care - from IRQ context.
30  */
31 void synchronize_irq(unsigned int irq)
32 {
33         struct irq_desc *desc = irq_to_desc(irq);
34         unsigned int status;
35
36         if (!desc)
37                 return;
38
39         do {
40                 unsigned long flags;
41
42                 /*
43                  * Wait until we're out of the critical section.  This might
44                  * give the wrong answer due to the lack of memory barriers.
45                  */
46                 while (desc->status & IRQ_INPROGRESS)
47                         cpu_relax();
48
49                 /* Ok, that indicated we're done: double-check carefully. */
50                 spin_lock_irqsave(&desc->lock, flags);
51                 status = desc->status;
52                 spin_unlock_irqrestore(&desc->lock, flags);
53
54                 /* Oops, that failed? */
55         } while (status & IRQ_INPROGRESS);
56 }
57 EXPORT_SYMBOL(synchronize_irq);
58
59 /**
60  *      irq_can_set_affinity - Check if the affinity of a given irq can be set
61  *      @irq:           Interrupt to check
62  *
63  */
64 int irq_can_set_affinity(unsigned int irq)
65 {
66         struct irq_desc *desc = irq_to_desc(irq);
67
68         if (CHECK_IRQ_PER_CPU(desc->status) || !desc->chip ||
69             !desc->chip->set_affinity)
70                 return 0;
71
72         return 1;
73 }
74
75 /**
76  *      irq_set_affinity - Set the irq affinity of a given irq
77  *      @irq:           Interrupt to set affinity
78  *      @cpumask:       cpumask
79  *
80  */
81 int irq_set_affinity(unsigned int irq, const struct cpumask *cpumask)
82 {
83         struct irq_desc *desc = irq_to_desc(irq);
84         unsigned long flags;
85
86         if (!desc->chip->set_affinity)
87                 return -EINVAL;
88
89         spin_lock_irqsave(&desc->lock, flags);
90
91 #ifdef CONFIG_GENERIC_PENDING_IRQ
92         if (desc->status & IRQ_MOVE_PCNTXT || desc->status & IRQ_DISABLED) {
93                 cpumask_copy(desc->affinity, cpumask);
94                 desc->chip->set_affinity(irq, cpumask);
95         } else {
96                 desc->status |= IRQ_MOVE_PENDING;
97                 cpumask_copy(desc->pending_mask, cpumask);
98         }
99 #else
100         cpumask_copy(desc->affinity, cpumask);
101         desc->chip->set_affinity(irq, cpumask);
102 #endif
103         desc->status |= IRQ_AFFINITY_SET;
104         spin_unlock_irqrestore(&desc->lock, flags);
105         return 0;
106 }
107
108 #ifndef CONFIG_AUTO_IRQ_AFFINITY
109 /*
110  * Generic version of the affinity autoselector.
111  */
112 static int setup_affinity(unsigned int irq, struct irq_desc *desc)
113 {
114         if (!irq_can_set_affinity(irq))
115                 return 0;
116
117         /*
118          * Preserve an userspace affinity setup, but make sure that
119          * one of the targets is online.
120          */
121         if (desc->status & (IRQ_AFFINITY_SET | IRQ_NO_BALANCING)) {
122                 if (cpumask_any_and(desc->affinity, cpu_online_mask)
123                     < nr_cpu_ids)
124                         goto set_affinity;
125                 else
126                         desc->status &= ~IRQ_AFFINITY_SET;
127         }
128
129         cpumask_and(desc->affinity, cpu_online_mask, irq_default_affinity);
130 set_affinity:
131         desc->chip->set_affinity(irq, desc->affinity);
132
133         return 0;
134 }
135 #else
136 static inline int setup_affinity(unsigned int irq, struct irq_desc *d)
137 {
138         return irq_select_affinity(irq);
139 }
140 #endif
141
142 /*
143  * Called when affinity is set via /proc/irq
144  */
145 int irq_select_affinity_usr(unsigned int irq)
146 {
147         struct irq_desc *desc = irq_to_desc(irq);
148         unsigned long flags;
149         int ret;
150
151         spin_lock_irqsave(&desc->lock, flags);
152         ret = setup_affinity(irq, desc);
153         spin_unlock_irqrestore(&desc->lock, flags);
154
155         return ret;
156 }
157
158 #else
159 static inline int setup_affinity(unsigned int irq, struct irq_desc *desc)
160 {
161         return 0;
162 }
163 #endif
164
165 void __disable_irq(struct irq_desc *desc, unsigned int irq, bool suspend)
166 {
167         if (suspend) {
168                 if (!desc->action || (desc->action->flags & IRQF_TIMER))
169                         return;
170                 desc->status |= IRQ_SUSPENDED;
171         }
172
173         if (!desc->depth++) {
174                 desc->status |= IRQ_DISABLED;
175                 desc->chip->disable(irq);
176         }
177 }
178
179 /**
180  *      disable_irq_nosync - disable an irq without waiting
181  *      @irq: Interrupt to disable
182  *
183  *      Disable the selected interrupt line.  Disables and Enables are
184  *      nested.
185  *      Unlike disable_irq(), this function does not ensure existing
186  *      instances of the IRQ handler have completed before returning.
187  *
188  *      This function may be called from IRQ context.
189  */
190 void disable_irq_nosync(unsigned int irq)
191 {
192         struct irq_desc *desc = irq_to_desc(irq);
193         unsigned long flags;
194
195         if (!desc)
196                 return;
197
198         spin_lock_irqsave(&desc->lock, flags);
199         __disable_irq(desc, irq, false);
200         spin_unlock_irqrestore(&desc->lock, flags);
201 }
202 EXPORT_SYMBOL(disable_irq_nosync);
203
204 /**
205  *      disable_irq - disable an irq and wait for completion
206  *      @irq: Interrupt to disable
207  *
208  *      Disable the selected interrupt line.  Enables and Disables are
209  *      nested.
210  *      This function waits for any pending IRQ handlers for this interrupt
211  *      to complete before returning. If you use this function while
212  *      holding a resource the IRQ handler may need you will deadlock.
213  *
214  *      This function may be called - with care - from IRQ context.
215  */
216 void disable_irq(unsigned int irq)
217 {
218         struct irq_desc *desc = irq_to_desc(irq);
219
220         if (!desc)
221                 return;
222
223         disable_irq_nosync(irq);
224         if (desc->action)
225                 synchronize_irq(irq);
226 }
227 EXPORT_SYMBOL(disable_irq);
228
229 void __enable_irq(struct irq_desc *desc, unsigned int irq, bool resume)
230 {
231         if (resume)
232                 desc->status &= ~IRQ_SUSPENDED;
233
234         switch (desc->depth) {
235         case 0:
236  err_out:
237                 WARN(1, KERN_WARNING "Unbalanced enable for IRQ %d\n", irq);
238                 break;
239         case 1: {
240                 unsigned int status = desc->status & ~IRQ_DISABLED;
241
242                 if (desc->status & IRQ_SUSPENDED)
243                         goto err_out;
244                 /* Prevent probing on this irq: */
245                 desc->status = status | IRQ_NOPROBE;
246                 check_irq_resend(desc, irq);
247                 /* fall-through */
248         }
249         default:
250                 desc->depth--;
251         }
252 }
253
254 /**
255  *      enable_irq - enable handling of an irq
256  *      @irq: Interrupt to enable
257  *
258  *      Undoes the effect of one call to disable_irq().  If this
259  *      matches the last disable, processing of interrupts on this
260  *      IRQ line is re-enabled.
261  *
262  *      This function may be called from IRQ context.
263  */
264 void enable_irq(unsigned int irq)
265 {
266         struct irq_desc *desc = irq_to_desc(irq);
267         unsigned long flags;
268
269         if (!desc)
270                 return;
271
272         spin_lock_irqsave(&desc->lock, flags);
273         __enable_irq(desc, irq, false);
274         spin_unlock_irqrestore(&desc->lock, flags);
275 }
276 EXPORT_SYMBOL(enable_irq);
277
278 static int set_irq_wake_real(unsigned int irq, unsigned int on)
279 {
280         struct irq_desc *desc = irq_to_desc(irq);
281         int ret = -ENXIO;
282
283         if (desc->chip->set_wake)
284                 ret = desc->chip->set_wake(irq, on);
285
286         return ret;
287 }
288
289 /**
290  *      set_irq_wake - control irq power management wakeup
291  *      @irq:   interrupt to control
292  *      @on:    enable/disable power management wakeup
293  *
294  *      Enable/disable power management wakeup mode, which is
295  *      disabled by default.  Enables and disables must match,
296  *      just as they match for non-wakeup mode support.
297  *
298  *      Wakeup mode lets this IRQ wake the system from sleep
299  *      states like "suspend to RAM".
300  */
301 int set_irq_wake(unsigned int irq, unsigned int on)
302 {
303         struct irq_desc *desc = irq_to_desc(irq);
304         unsigned long flags;
305         int ret = 0;
306
307         /* wakeup-capable irqs can be shared between drivers that
308          * don't need to have the same sleep mode behaviors.
309          */
310         spin_lock_irqsave(&desc->lock, flags);
311         if (on) {
312                 if (desc->wake_depth++ == 0) {
313                         ret = set_irq_wake_real(irq, on);
314                         if (ret)
315                                 desc->wake_depth = 0;
316                         else
317                                 desc->status |= IRQ_WAKEUP;
318                 }
319         } else {
320                 if (desc->wake_depth == 0) {
321                         WARN(1, "Unbalanced IRQ %d wake disable\n", irq);
322                 } else if (--desc->wake_depth == 0) {
323                         ret = set_irq_wake_real(irq, on);
324                         if (ret)
325                                 desc->wake_depth = 1;
326                         else
327                                 desc->status &= ~IRQ_WAKEUP;
328                 }
329         }
330
331         spin_unlock_irqrestore(&desc->lock, flags);
332         return ret;
333 }
334 EXPORT_SYMBOL(set_irq_wake);
335
336 /*
337  * Internal function that tells the architecture code whether a
338  * particular irq has been exclusively allocated or is available
339  * for driver use.
340  */
341 int can_request_irq(unsigned int irq, unsigned long irqflags)
342 {
343         struct irq_desc *desc = irq_to_desc(irq);
344         struct irqaction *action;
345
346         if (!desc)
347                 return 0;
348
349         if (desc->status & IRQ_NOREQUEST)
350                 return 0;
351
352         action = desc->action;
353         if (action)
354                 if (irqflags & action->flags & IRQF_SHARED)
355                         action = NULL;
356
357         return !action;
358 }
359
360 void compat_irq_chip_set_default_handler(struct irq_desc *desc)
361 {
362         /*
363          * If the architecture still has not overriden
364          * the flow handler then zap the default. This
365          * should catch incorrect flow-type setting.
366          */
367         if (desc->handle_irq == &handle_bad_irq)
368                 desc->handle_irq = NULL;
369 }
370
371 int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
372                 unsigned long flags)
373 {
374         int ret;
375         struct irq_chip *chip = desc->chip;
376
377         if (!chip || !chip->set_type) {
378                 /*
379                  * IRQF_TRIGGER_* but the PIC does not support multiple
380                  * flow-types?
381                  */
382                 pr_debug("No set_type function for IRQ %d (%s)\n", irq,
383                                 chip ? (chip->name ? : "unknown") : "unknown");
384                 return 0;
385         }
386
387         /* caller masked out all except trigger mode flags */
388         ret = chip->set_type(irq, flags);
389
390         if (ret)
391                 pr_err("setting trigger mode %d for irq %u failed (%pF)\n",
392                                 (int)flags, irq, chip->set_type);
393         else {
394                 if (flags & (IRQ_TYPE_LEVEL_LOW | IRQ_TYPE_LEVEL_HIGH))
395                         flags |= IRQ_LEVEL;
396                 /* note that IRQF_TRIGGER_MASK == IRQ_TYPE_SENSE_MASK */
397                 desc->status &= ~(IRQ_LEVEL | IRQ_TYPE_SENSE_MASK);
398                 desc->status |= flags;
399         }
400
401         return ret;
402 }
403
404 /*
405  * Internal function to register an irqaction - typically used to
406  * allocate special interrupts that are part of the architecture.
407  */
408 static int
409 __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
410 {
411         struct irqaction *old, **old_ptr;
412         const char *old_name = NULL;
413         unsigned long flags;
414         int shared = 0;
415         int ret;
416
417         if (!desc)
418                 return -EINVAL;
419
420         if (desc->chip == &no_irq_chip)
421                 return -ENOSYS;
422         /*
423          * Some drivers like serial.c use request_irq() heavily,
424          * so we have to be careful not to interfere with a
425          * running system.
426          */
427         if (new->flags & IRQF_SAMPLE_RANDOM) {
428                 /*
429                  * This function might sleep, we want to call it first,
430                  * outside of the atomic block.
431                  * Yes, this might clear the entropy pool if the wrong
432                  * driver is attempted to be loaded, without actually
433                  * installing a new handler, but is this really a problem,
434                  * only the sysadmin is able to do this.
435                  */
436                 rand_initialize_irq(irq);
437         }
438
439         /*
440          * The following block of code has to be executed atomically
441          */
442         spin_lock_irqsave(&desc->lock, flags);
443         old_ptr = &desc->action;
444         old = *old_ptr;
445         if (old) {
446                 /*
447                  * Can't share interrupts unless both agree to and are
448                  * the same type (level, edge, polarity). So both flag
449                  * fields must have IRQF_SHARED set and the bits which
450                  * set the trigger type must match.
451                  */
452                 if (!((old->flags & new->flags) & IRQF_SHARED) ||
453                     ((old->flags ^ new->flags) & IRQF_TRIGGER_MASK)) {
454                         old_name = old->name;
455                         goto mismatch;
456                 }
457
458 #if defined(CONFIG_IRQ_PER_CPU)
459                 /* All handlers must agree on per-cpuness */
460                 if ((old->flags & IRQF_PERCPU) !=
461                     (new->flags & IRQF_PERCPU))
462                         goto mismatch;
463 #endif
464
465                 /* add new interrupt at end of irq queue */
466                 do {
467                         old_ptr = &old->next;
468                         old = *old_ptr;
469                 } while (old);
470                 shared = 1;
471         }
472
473         if (!shared) {
474                 irq_chip_set_defaults(desc->chip);
475
476                 /* Setup the type (level, edge polarity) if configured: */
477                 if (new->flags & IRQF_TRIGGER_MASK) {
478                         ret = __irq_set_trigger(desc, irq,
479                                         new->flags & IRQF_TRIGGER_MASK);
480
481                         if (ret) {
482                                 spin_unlock_irqrestore(&desc->lock, flags);
483                                 return ret;
484                         }
485                 } else
486                         compat_irq_chip_set_default_handler(desc);
487 #if defined(CONFIG_IRQ_PER_CPU)
488                 if (new->flags & IRQF_PERCPU)
489                         desc->status |= IRQ_PER_CPU;
490 #endif
491
492                 desc->status &= ~(IRQ_AUTODETECT | IRQ_WAITING |
493                                   IRQ_INPROGRESS | IRQ_SPURIOUS_DISABLED);
494
495                 if (!(desc->status & IRQ_NOAUTOEN)) {
496                         desc->depth = 0;
497                         desc->status &= ~IRQ_DISABLED;
498                         desc->chip->startup(irq);
499                 } else
500                         /* Undo nested disables: */
501                         desc->depth = 1;
502
503                 /* Exclude IRQ from balancing if requested */
504                 if (new->flags & IRQF_NOBALANCING)
505                         desc->status |= IRQ_NO_BALANCING;
506
507                 /* Set default affinity mask once everything is setup */
508                 setup_affinity(irq, desc);
509
510         } else if ((new->flags & IRQF_TRIGGER_MASK)
511                         && (new->flags & IRQF_TRIGGER_MASK)
512                                 != (desc->status & IRQ_TYPE_SENSE_MASK)) {
513                 /* hope the handler works with the actual trigger mode... */
514                 pr_warning("IRQ %d uses trigger mode %d; requested %d\n",
515                                 irq, (int)(desc->status & IRQ_TYPE_SENSE_MASK),
516                                 (int)(new->flags & IRQF_TRIGGER_MASK));
517         }
518
519         *old_ptr = new;
520
521         /* Reset broken irq detection when installing new handler */
522         desc->irq_count = 0;
523         desc->irqs_unhandled = 0;
524
525         /*
526          * Check whether we disabled the irq via the spurious handler
527          * before. Reenable it and give it another chance.
528          */
529         if (shared && (desc->status & IRQ_SPURIOUS_DISABLED)) {
530                 desc->status &= ~IRQ_SPURIOUS_DISABLED;
531                 __enable_irq(desc, irq, false);
532         }
533
534         spin_unlock_irqrestore(&desc->lock, flags);
535
536         new->irq = irq;
537         register_irq_proc(irq, desc);
538         new->dir = NULL;
539         register_handler_proc(irq, new);
540
541         return 0;
542
543 mismatch:
544 #ifdef CONFIG_DEBUG_SHIRQ
545         if (!(new->flags & IRQF_PROBE_SHARED)) {
546                 printk(KERN_ERR "IRQ handler type mismatch for IRQ %d\n", irq);
547                 if (old_name)
548                         printk(KERN_ERR "current handler: %s\n", old_name);
549                 dump_stack();
550         }
551 #endif
552         spin_unlock_irqrestore(&desc->lock, flags);
553         return -EBUSY;
554 }
555
556 /**
557  *      setup_irq - setup an interrupt
558  *      @irq: Interrupt line to setup
559  *      @act: irqaction for the interrupt
560  *
561  * Used to statically setup interrupts in the early boot process.
562  */
563 int setup_irq(unsigned int irq, struct irqaction *act)
564 {
565         struct irq_desc *desc = irq_to_desc(irq);
566
567         return __setup_irq(irq, desc, act);
568 }
569 EXPORT_SYMBOL_GPL(setup_irq);
570
571  /*
572  * Internal function to unregister an irqaction - used to free
573  * regular and special interrupts that are part of the architecture.
574  */
575 static struct irqaction *__free_irq(unsigned int irq, void *dev_id)
576 {
577         struct irq_desc *desc = irq_to_desc(irq);
578         struct irqaction *action, **action_ptr;
579         unsigned long flags;
580
581         WARN(in_interrupt(), "Trying to free IRQ %d from IRQ context!\n", irq);
582
583         if (!desc)
584                 return NULL;
585
586         spin_lock_irqsave(&desc->lock, flags);
587
588         /*
589          * There can be multiple actions per IRQ descriptor, find the right
590          * one based on the dev_id:
591          */
592         action_ptr = &desc->action;
593         for (;;) {
594                 action = *action_ptr;
595
596                 if (!action) {
597                         WARN(1, "Trying to free already-free IRQ %d\n", irq);
598                         spin_unlock_irqrestore(&desc->lock, flags);
599
600                         return NULL;
601                 }
602
603                 if (action->dev_id == dev_id)
604                         break;
605                 action_ptr = &action->next;
606         }
607
608         /* Found it - now remove it from the list of entries: */
609         *action_ptr = action->next;
610
611         /* Currently used only by UML, might disappear one day: */
612 #ifdef CONFIG_IRQ_RELEASE_METHOD
613         if (desc->chip->release)
614                 desc->chip->release(irq, dev_id);
615 #endif
616
617         /* If this was the last handler, shut down the IRQ line: */
618         if (!desc->action) {
619                 desc->status |= IRQ_DISABLED;
620                 if (desc->chip->shutdown)
621                         desc->chip->shutdown(irq);
622                 else
623                         desc->chip->disable(irq);
624         }
625         spin_unlock_irqrestore(&desc->lock, flags);
626
627         unregister_handler_proc(irq, action);
628
629         /* Make sure it's not being used on another CPU: */
630         synchronize_irq(irq);
631
632 #ifdef CONFIG_DEBUG_SHIRQ
633         /*
634          * It's a shared IRQ -- the driver ought to be prepared for an IRQ
635          * event to happen even now it's being freed, so let's make sure that
636          * is so by doing an extra call to the handler ....
637          *
638          * ( We do this after actually deregistering it, to make sure that a
639          *   'real' IRQ doesn't run in * parallel with our fake. )
640          */
641         if (action->flags & IRQF_SHARED) {
642                 local_irq_save(flags);
643                 action->handler(irq, dev_id);
644                 local_irq_restore(flags);
645         }
646 #endif
647         return action;
648 }
649
650 /**
651  *      remove_irq - free an interrupt
652  *      @irq: Interrupt line to free
653  *      @act: irqaction for the interrupt
654  *
655  * Used to remove interrupts statically setup by the early boot process.
656  */
657 void remove_irq(unsigned int irq, struct irqaction *act)
658 {
659         __free_irq(irq, act->dev_id);
660 }
661 EXPORT_SYMBOL_GPL(remove_irq);
662
663 /**
664  *      free_irq - free an interrupt allocated with request_irq
665  *      @irq: Interrupt line to free
666  *      @dev_id: Device identity to free
667  *
668  *      Remove an interrupt handler. The handler is removed and if the
669  *      interrupt line is no longer in use by any driver it is disabled.
670  *      On a shared IRQ the caller must ensure the interrupt is disabled
671  *      on the card it drives before calling this function. The function
672  *      does not return until any executing interrupts for this IRQ
673  *      have completed.
674  *
675  *      This function must not be called from interrupt context.
676  */
677 void free_irq(unsigned int irq, void *dev_id)
678 {
679         kfree(__free_irq(irq, dev_id));
680 }
681 EXPORT_SYMBOL(free_irq);
682
683 /**
684  *      request_irq - allocate an interrupt line
685  *      @irq: Interrupt line to allocate
686  *      @handler: Function to be called when the IRQ occurs
687  *      @irqflags: Interrupt type flags
688  *      @devname: An ascii name for the claiming device
689  *      @dev_id: A cookie passed back to the handler function
690  *
691  *      This call allocates interrupt resources and enables the
692  *      interrupt line and IRQ handling. From the point this
693  *      call is made your handler function may be invoked. Since
694  *      your handler function must clear any interrupt the board
695  *      raises, you must take care both to initialise your hardware
696  *      and to set up the interrupt handler in the right order.
697  *
698  *      Dev_id must be globally unique. Normally the address of the
699  *      device data structure is used as the cookie. Since the handler
700  *      receives this value it makes sense to use it.
701  *
702  *      If your interrupt is shared you must pass a non NULL dev_id
703  *      as this is required when freeing the interrupt.
704  *
705  *      Flags:
706  *
707  *      IRQF_SHARED             Interrupt is shared
708  *      IRQF_DISABLED   Disable local interrupts while processing
709  *      IRQF_SAMPLE_RANDOM      The interrupt can be used for entropy
710  *      IRQF_TRIGGER_*          Specify active edge(s) or level
711  *
712  */
713 int request_irq(unsigned int irq, irq_handler_t handler,
714                 unsigned long irqflags, const char *devname, void *dev_id)
715 {
716         struct irqaction *action;
717         struct irq_desc *desc;
718         int retval;
719
720         /*
721          * handle_IRQ_event() always ignores IRQF_DISABLED except for
722          * the _first_ irqaction (sigh).  That can cause oopsing, but
723          * the behavior is classified as "will not fix" so we need to
724          * start nudging drivers away from using that idiom.
725          */
726         if ((irqflags & (IRQF_SHARED|IRQF_DISABLED)) ==
727                                         (IRQF_SHARED|IRQF_DISABLED)) {
728                 pr_warning(
729                   "IRQ %d/%s: IRQF_DISABLED is not guaranteed on shared IRQs\n",
730                         irq, devname);
731         }
732
733 #ifdef CONFIG_LOCKDEP
734         /*
735          * Lockdep wants atomic interrupt handlers:
736          */
737         irqflags |= IRQF_DISABLED;
738 #endif
739         /*
740          * Sanity-check: shared interrupts must pass in a real dev-ID,
741          * otherwise we'll have trouble later trying to figure out
742          * which interrupt is which (messes up the interrupt freeing
743          * logic etc).
744          */
745         if ((irqflags & IRQF_SHARED) && !dev_id)
746                 return -EINVAL;
747
748         desc = irq_to_desc(irq);
749         if (!desc)
750                 return -EINVAL;
751
752         if (desc->status & IRQ_NOREQUEST)
753                 return -EINVAL;
754         if (!handler)
755                 return -EINVAL;
756
757         action = kzalloc(sizeof(struct irqaction), GFP_KERNEL);
758         if (!action)
759                 return -ENOMEM;
760
761         action->handler = handler;
762         action->flags = irqflags;
763         action->name = devname;
764         action->dev_id = dev_id;
765
766         retval = __setup_irq(irq, desc, action);
767         if (retval)
768                 kfree(action);
769
770 #ifdef CONFIG_DEBUG_SHIRQ
771         if (!retval && (irqflags & IRQF_SHARED)) {
772                 /*
773                  * It's a shared IRQ -- the driver ought to be prepared for it
774                  * to happen immediately, so let's make sure....
775                  * We disable the irq to make sure that a 'real' IRQ doesn't
776                  * run in parallel with our fake.
777                  */
778                 unsigned long flags;
779
780                 disable_irq(irq);
781                 local_irq_save(flags);
782
783                 handler(irq, dev_id);
784
785                 local_irq_restore(flags);
786                 enable_irq(irq);
787         }
788 #endif
789         return retval;
790 }
791 EXPORT_SYMBOL(request_irq);