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Merge branch 'for-2.6.26' of master.kernel.org:/pub/scm/linux/kernel/git/jwboyer...
[linux-2.6] / 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 /**
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_desc + irq;
33         unsigned int status;
34
35         if (irq >= NR_IRQS)
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 EXPORT_SYMBOL(synchronize_irq);
57
58 /**
59  *      irq_can_set_affinity - Check if the affinity of a given irq can be set
60  *      @irq:           Interrupt to check
61  *
62  */
63 int irq_can_set_affinity(unsigned int irq)
64 {
65         struct irq_desc *desc = irq_desc + irq;
66
67         if (CHECK_IRQ_PER_CPU(desc->status) || !desc->chip ||
68             !desc->chip->set_affinity)
69                 return 0;
70
71         return 1;
72 }
73
74 /**
75  *      irq_set_affinity - Set the irq affinity of a given irq
76  *      @irq:           Interrupt to set affinity
77  *      @cpumask:       cpumask
78  *
79  */
80 int irq_set_affinity(unsigned int irq, cpumask_t cpumask)
81 {
82         struct irq_desc *desc = irq_desc + irq;
83
84         if (!desc->chip->set_affinity)
85                 return -EINVAL;
86
87         set_balance_irq_affinity(irq, cpumask);
88
89 #ifdef CONFIG_GENERIC_PENDING_IRQ
90         set_pending_irq(irq, cpumask);
91 #else
92         desc->affinity = cpumask;
93         desc->chip->set_affinity(irq, cpumask);
94 #endif
95         return 0;
96 }
97
98 #endif
99
100 /**
101  *      disable_irq_nosync - disable an irq without waiting
102  *      @irq: Interrupt to disable
103  *
104  *      Disable the selected interrupt line.  Disables and Enables are
105  *      nested.
106  *      Unlike disable_irq(), this function does not ensure existing
107  *      instances of the IRQ handler have completed before returning.
108  *
109  *      This function may be called from IRQ context.
110  */
111 void disable_irq_nosync(unsigned int irq)
112 {
113         struct irq_desc *desc = irq_desc + irq;
114         unsigned long flags;
115
116         if (irq >= NR_IRQS)
117                 return;
118
119         spin_lock_irqsave(&desc->lock, flags);
120         if (!desc->depth++) {
121                 desc->status |= IRQ_DISABLED;
122                 desc->chip->disable(irq);
123         }
124         spin_unlock_irqrestore(&desc->lock, flags);
125 }
126 EXPORT_SYMBOL(disable_irq_nosync);
127
128 /**
129  *      disable_irq - disable an irq and wait for completion
130  *      @irq: Interrupt to disable
131  *
132  *      Disable the selected interrupt line.  Enables and Disables are
133  *      nested.
134  *      This function waits for any pending IRQ handlers for this interrupt
135  *      to complete before returning. If you use this function while
136  *      holding a resource the IRQ handler may need you will deadlock.
137  *
138  *      This function may be called - with care - from IRQ context.
139  */
140 void disable_irq(unsigned int irq)
141 {
142         struct irq_desc *desc = irq_desc + irq;
143
144         if (irq >= NR_IRQS)
145                 return;
146
147         disable_irq_nosync(irq);
148         if (desc->action)
149                 synchronize_irq(irq);
150 }
151 EXPORT_SYMBOL(disable_irq);
152
153 static void __enable_irq(struct irq_desc *desc, unsigned int irq)
154 {
155         switch (desc->depth) {
156         case 0:
157                 printk(KERN_WARNING "Unbalanced enable for IRQ %d\n", irq);
158                 WARN_ON(1);
159                 break;
160         case 1: {
161                 unsigned int status = desc->status & ~IRQ_DISABLED;
162
163                 /* Prevent probing on this irq: */
164                 desc->status = status | IRQ_NOPROBE;
165                 check_irq_resend(desc, irq);
166                 /* fall-through */
167         }
168         default:
169                 desc->depth--;
170         }
171 }
172
173 /**
174  *      enable_irq - enable handling of an irq
175  *      @irq: Interrupt to enable
176  *
177  *      Undoes the effect of one call to disable_irq().  If this
178  *      matches the last disable, processing of interrupts on this
179  *      IRQ line is re-enabled.
180  *
181  *      This function may be called from IRQ context.
182  */
183 void enable_irq(unsigned int irq)
184 {
185         struct irq_desc *desc = irq_desc + irq;
186         unsigned long flags;
187
188         if (irq >= NR_IRQS)
189                 return;
190
191         spin_lock_irqsave(&desc->lock, flags);
192         __enable_irq(desc, irq);
193         spin_unlock_irqrestore(&desc->lock, flags);
194 }
195 EXPORT_SYMBOL(enable_irq);
196
197 /**
198  *      set_irq_wake - control irq power management wakeup
199  *      @irq:   interrupt to control
200  *      @on:    enable/disable power management wakeup
201  *
202  *      Enable/disable power management wakeup mode, which is
203  *      disabled by default.  Enables and disables must match,
204  *      just as they match for non-wakeup mode support.
205  *
206  *      Wakeup mode lets this IRQ wake the system from sleep
207  *      states like "suspend to RAM".
208  */
209 int set_irq_wake(unsigned int irq, unsigned int on)
210 {
211         struct irq_desc *desc = irq_desc + irq;
212         unsigned long flags;
213         int ret = -ENXIO;
214         int (*set_wake)(unsigned, unsigned) = desc->chip->set_wake;
215
216         /* wakeup-capable irqs can be shared between drivers that
217          * don't need to have the same sleep mode behaviors.
218          */
219         spin_lock_irqsave(&desc->lock, flags);
220         if (on) {
221                 if (desc->wake_depth++ == 0)
222                         desc->status |= IRQ_WAKEUP;
223                 else
224                         set_wake = NULL;
225         } else {
226                 if (desc->wake_depth == 0) {
227                         printk(KERN_WARNING "Unbalanced IRQ %d "
228                                         "wake disable\n", irq);
229                         WARN_ON(1);
230                 } else if (--desc->wake_depth == 0)
231                         desc->status &= ~IRQ_WAKEUP;
232                 else
233                         set_wake = NULL;
234         }
235         if (set_wake)
236                 ret = desc->chip->set_wake(irq, on);
237         spin_unlock_irqrestore(&desc->lock, flags);
238         return ret;
239 }
240 EXPORT_SYMBOL(set_irq_wake);
241
242 /*
243  * Internal function that tells the architecture code whether a
244  * particular irq has been exclusively allocated or is available
245  * for driver use.
246  */
247 int can_request_irq(unsigned int irq, unsigned long irqflags)
248 {
249         struct irqaction *action;
250
251         if (irq >= NR_IRQS || irq_desc[irq].status & IRQ_NOREQUEST)
252                 return 0;
253
254         action = irq_desc[irq].action;
255         if (action)
256                 if (irqflags & action->flags & IRQF_SHARED)
257                         action = NULL;
258
259         return !action;
260 }
261
262 void compat_irq_chip_set_default_handler(struct irq_desc *desc)
263 {
264         /*
265          * If the architecture still has not overriden
266          * the flow handler then zap the default. This
267          * should catch incorrect flow-type setting.
268          */
269         if (desc->handle_irq == &handle_bad_irq)
270                 desc->handle_irq = NULL;
271 }
272
273 /*
274  * Internal function to register an irqaction - typically used to
275  * allocate special interrupts that are part of the architecture.
276  */
277 int setup_irq(unsigned int irq, struct irqaction *new)
278 {
279         struct irq_desc *desc = irq_desc + irq;
280         struct irqaction *old, **p;
281         const char *old_name = NULL;
282         unsigned long flags;
283         int shared = 0;
284
285         if (irq >= NR_IRQS)
286                 return -EINVAL;
287
288         if (desc->chip == &no_irq_chip)
289                 return -ENOSYS;
290         /*
291          * Some drivers like serial.c use request_irq() heavily,
292          * so we have to be careful not to interfere with a
293          * running system.
294          */
295         if (new->flags & IRQF_SAMPLE_RANDOM) {
296                 /*
297                  * This function might sleep, we want to call it first,
298                  * outside of the atomic block.
299                  * Yes, this might clear the entropy pool if the wrong
300                  * driver is attempted to be loaded, without actually
301                  * installing a new handler, but is this really a problem,
302                  * only the sysadmin is able to do this.
303                  */
304                 rand_initialize_irq(irq);
305         }
306
307         /*
308          * The following block of code has to be executed atomically
309          */
310         spin_lock_irqsave(&desc->lock, flags);
311         p = &desc->action;
312         old = *p;
313         if (old) {
314                 /*
315                  * Can't share interrupts unless both agree to and are
316                  * the same type (level, edge, polarity). So both flag
317                  * fields must have IRQF_SHARED set and the bits which
318                  * set the trigger type must match.
319                  */
320                 if (!((old->flags & new->flags) & IRQF_SHARED) ||
321                     ((old->flags ^ new->flags) & IRQF_TRIGGER_MASK)) {
322                         old_name = old->name;
323                         goto mismatch;
324                 }
325
326 #if defined(CONFIG_IRQ_PER_CPU)
327                 /* All handlers must agree on per-cpuness */
328                 if ((old->flags & IRQF_PERCPU) !=
329                     (new->flags & IRQF_PERCPU))
330                         goto mismatch;
331 #endif
332
333                 /* add new interrupt at end of irq queue */
334                 do {
335                         p = &old->next;
336                         old = *p;
337                 } while (old);
338                 shared = 1;
339         }
340
341         *p = new;
342
343         /* Exclude IRQ from balancing */
344         if (new->flags & IRQF_NOBALANCING)
345                 desc->status |= IRQ_NO_BALANCING;
346
347         if (!shared) {
348                 irq_chip_set_defaults(desc->chip);
349
350 #if defined(CONFIG_IRQ_PER_CPU)
351                 if (new->flags & IRQF_PERCPU)
352                         desc->status |= IRQ_PER_CPU;
353 #endif
354
355                 /* Setup the type (level, edge polarity) if configured: */
356                 if (new->flags & IRQF_TRIGGER_MASK) {
357                         if (desc->chip && desc->chip->set_type)
358                                 desc->chip->set_type(irq,
359                                                 new->flags & IRQF_TRIGGER_MASK);
360                         else
361                                 /*
362                                  * IRQF_TRIGGER_* but the PIC does not support
363                                  * multiple flow-types?
364                                  */
365                                 printk(KERN_WARNING "No IRQF_TRIGGER set_type "
366                                        "function for IRQ %d (%s)\n", irq,
367                                        desc->chip ? desc->chip->name :
368                                        "unknown");
369                 } else
370                         compat_irq_chip_set_default_handler(desc);
371
372                 desc->status &= ~(IRQ_AUTODETECT | IRQ_WAITING |
373                                   IRQ_INPROGRESS | IRQ_SPURIOUS_DISABLED);
374
375                 if (!(desc->status & IRQ_NOAUTOEN)) {
376                         desc->depth = 0;
377                         desc->status &= ~IRQ_DISABLED;
378                         if (desc->chip->startup)
379                                 desc->chip->startup(irq);
380                         else
381                                 desc->chip->enable(irq);
382                 } else
383                         /* Undo nested disables: */
384                         desc->depth = 1;
385         }
386         /* Reset broken irq detection when installing new handler */
387         desc->irq_count = 0;
388         desc->irqs_unhandled = 0;
389
390         /*
391          * Check whether we disabled the irq via the spurious handler
392          * before. Reenable it and give it another chance.
393          */
394         if (shared && (desc->status & IRQ_SPURIOUS_DISABLED)) {
395                 desc->status &= ~IRQ_SPURIOUS_DISABLED;
396                 __enable_irq(desc, irq);
397         }
398
399         spin_unlock_irqrestore(&desc->lock, flags);
400
401         new->irq = irq;
402         register_irq_proc(irq);
403         new->dir = NULL;
404         register_handler_proc(irq, new);
405
406         return 0;
407
408 mismatch:
409 #ifdef CONFIG_DEBUG_SHIRQ
410         if (!(new->flags & IRQF_PROBE_SHARED)) {
411                 printk(KERN_ERR "IRQ handler type mismatch for IRQ %d\n", irq);
412                 if (old_name)
413                         printk(KERN_ERR "current handler: %s\n", old_name);
414                 dump_stack();
415         }
416 #endif
417         spin_unlock_irqrestore(&desc->lock, flags);
418         return -EBUSY;
419 }
420
421 /**
422  *      free_irq - free an interrupt
423  *      @irq: Interrupt line to free
424  *      @dev_id: Device identity to free
425  *
426  *      Remove an interrupt handler. The handler is removed and if the
427  *      interrupt line is no longer in use by any driver it is disabled.
428  *      On a shared IRQ the caller must ensure the interrupt is disabled
429  *      on the card it drives before calling this function. The function
430  *      does not return until any executing interrupts for this IRQ
431  *      have completed.
432  *
433  *      This function must not be called from interrupt context.
434  */
435 void free_irq(unsigned int irq, void *dev_id)
436 {
437         struct irq_desc *desc;
438         struct irqaction **p;
439         unsigned long flags;
440
441         WARN_ON(in_interrupt());
442         if (irq >= NR_IRQS)
443                 return;
444
445         desc = irq_desc + irq;
446         spin_lock_irqsave(&desc->lock, flags);
447         p = &desc->action;
448         for (;;) {
449                 struct irqaction *action = *p;
450
451                 if (action) {
452                         struct irqaction **pp = p;
453
454                         p = &action->next;
455                         if (action->dev_id != dev_id)
456                                 continue;
457
458                         /* Found it - now remove it from the list of entries */
459                         *pp = action->next;
460
461                         /* Currently used only by UML, might disappear one day.*/
462 #ifdef CONFIG_IRQ_RELEASE_METHOD
463                         if (desc->chip->release)
464                                 desc->chip->release(irq, dev_id);
465 #endif
466
467                         if (!desc->action) {
468                                 desc->status |= IRQ_DISABLED;
469                                 if (desc->chip->shutdown)
470                                         desc->chip->shutdown(irq);
471                                 else
472                                         desc->chip->disable(irq);
473                         }
474                         spin_unlock_irqrestore(&desc->lock, flags);
475                         unregister_handler_proc(irq, action);
476
477                         /* Make sure it's not being used on another CPU */
478                         synchronize_irq(irq);
479 #ifdef CONFIG_DEBUG_SHIRQ
480                         /*
481                          * It's a shared IRQ -- the driver ought to be
482                          * prepared for it to happen even now it's
483                          * being freed, so let's make sure....  We do
484                          * this after actually deregistering it, to
485                          * make sure that a 'real' IRQ doesn't run in
486                          * parallel with our fake
487                          */
488                         if (action->flags & IRQF_SHARED) {
489                                 local_irq_save(flags);
490                                 action->handler(irq, dev_id);
491                                 local_irq_restore(flags);
492                         }
493 #endif
494                         kfree(action);
495                         return;
496                 }
497                 printk(KERN_ERR "Trying to free already-free IRQ %d\n", irq);
498 #ifdef CONFIG_DEBUG_SHIRQ
499                 dump_stack();
500 #endif
501                 spin_unlock_irqrestore(&desc->lock, flags);
502                 return;
503         }
504 }
505 EXPORT_SYMBOL(free_irq);
506
507 /**
508  *      request_irq - allocate an interrupt line
509  *      @irq: Interrupt line to allocate
510  *      @handler: Function to be called when the IRQ occurs
511  *      @irqflags: Interrupt type flags
512  *      @devname: An ascii name for the claiming device
513  *      @dev_id: A cookie passed back to the handler function
514  *
515  *      This call allocates interrupt resources and enables the
516  *      interrupt line and IRQ handling. From the point this
517  *      call is made your handler function may be invoked. Since
518  *      your handler function must clear any interrupt the board
519  *      raises, you must take care both to initialise your hardware
520  *      and to set up the interrupt handler in the right order.
521  *
522  *      Dev_id must be globally unique. Normally the address of the
523  *      device data structure is used as the cookie. Since the handler
524  *      receives this value it makes sense to use it.
525  *
526  *      If your interrupt is shared you must pass a non NULL dev_id
527  *      as this is required when freeing the interrupt.
528  *
529  *      Flags:
530  *
531  *      IRQF_SHARED             Interrupt is shared
532  *      IRQF_DISABLED   Disable local interrupts while processing
533  *      IRQF_SAMPLE_RANDOM      The interrupt can be used for entropy
534  *
535  */
536 int request_irq(unsigned int irq, irq_handler_t handler,
537                 unsigned long irqflags, const char *devname, void *dev_id)
538 {
539         struct irqaction *action;
540         int retval;
541
542 #ifdef CONFIG_LOCKDEP
543         /*
544          * Lockdep wants atomic interrupt handlers:
545          */
546         irqflags |= IRQF_DISABLED;
547 #endif
548         /*
549          * Sanity-check: shared interrupts must pass in a real dev-ID,
550          * otherwise we'll have trouble later trying to figure out
551          * which interrupt is which (messes up the interrupt freeing
552          * logic etc).
553          */
554         if ((irqflags & IRQF_SHARED) && !dev_id)
555                 return -EINVAL;
556         if (irq >= NR_IRQS)
557                 return -EINVAL;
558         if (irq_desc[irq].status & IRQ_NOREQUEST)
559                 return -EINVAL;
560         if (!handler)
561                 return -EINVAL;
562
563         action = kmalloc(sizeof(struct irqaction), GFP_ATOMIC);
564         if (!action)
565                 return -ENOMEM;
566
567         action->handler = handler;
568         action->flags = irqflags;
569         cpus_clear(action->mask);
570         action->name = devname;
571         action->next = NULL;
572         action->dev_id = dev_id;
573
574         select_smp_affinity(irq);
575
576 #ifdef CONFIG_DEBUG_SHIRQ
577         if (irqflags & IRQF_SHARED) {
578                 /*
579                  * It's a shared IRQ -- the driver ought to be prepared for it
580                  * to happen immediately, so let's make sure....
581                  * We do this before actually registering it, to make sure that
582                  * a 'real' IRQ doesn't run in parallel with our fake
583                  */
584                 unsigned long flags;
585
586                 local_irq_save(flags);
587                 handler(irq, dev_id);
588                 local_irq_restore(flags);
589         }
590 #endif
591
592         retval = setup_irq(irq, action);
593         if (retval)
594                 kfree(action);
595
596         return retval;
597 }
598 EXPORT_SYMBOL(request_irq);