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