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