x86: apic_ops for lguest
[sfrench/cifs-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 /**
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         if (desc->status & IRQ_MOVE_PCNTXT) {
91                 unsigned long flags;
92
93                 spin_lock_irqsave(&desc->lock, flags);
94                 desc->chip->set_affinity(irq, cpumask);
95                 spin_unlock_irqrestore(&desc->lock, flags);
96         } else
97                 set_pending_irq(irq, cpumask);
98 #else
99         desc->affinity = cpumask;
100         desc->chip->set_affinity(irq, cpumask);
101 #endif
102         return 0;
103 }
104
105 #endif
106
107 /**
108  *      disable_irq_nosync - disable an irq without waiting
109  *      @irq: Interrupt to disable
110  *
111  *      Disable the selected interrupt line.  Disables and Enables are
112  *      nested.
113  *      Unlike disable_irq(), this function does not ensure existing
114  *      instances of the IRQ handler have completed before returning.
115  *
116  *      This function may be called from IRQ context.
117  */
118 void disable_irq_nosync(unsigned int irq)
119 {
120         struct irq_desc *desc = irq_desc + irq;
121         unsigned long flags;
122
123         if (irq >= NR_IRQS)
124                 return;
125
126         spin_lock_irqsave(&desc->lock, flags);
127         if (!desc->depth++) {
128                 desc->status |= IRQ_DISABLED;
129                 desc->chip->disable(irq);
130         }
131         spin_unlock_irqrestore(&desc->lock, flags);
132 }
133 EXPORT_SYMBOL(disable_irq_nosync);
134
135 /**
136  *      disable_irq - disable an irq and wait for completion
137  *      @irq: Interrupt to disable
138  *
139  *      Disable the selected interrupt line.  Enables and Disables are
140  *      nested.
141  *      This function waits for any pending IRQ handlers for this interrupt
142  *      to complete before returning. If you use this function while
143  *      holding a resource the IRQ handler may need you will deadlock.
144  *
145  *      This function may be called - with care - from IRQ context.
146  */
147 void disable_irq(unsigned int irq)
148 {
149         struct irq_desc *desc = irq_desc + irq;
150
151         if (irq >= NR_IRQS)
152                 return;
153
154         disable_irq_nosync(irq);
155         if (desc->action)
156                 synchronize_irq(irq);
157 }
158 EXPORT_SYMBOL(disable_irq);
159
160 static void __enable_irq(struct irq_desc *desc, unsigned int irq)
161 {
162         switch (desc->depth) {
163         case 0:
164                 printk(KERN_WARNING "Unbalanced enable for IRQ %d\n", irq);
165                 WARN_ON(1);
166                 break;
167         case 1: {
168                 unsigned int status = desc->status & ~IRQ_DISABLED;
169
170                 /* Prevent probing on this irq: */
171                 desc->status = status | IRQ_NOPROBE;
172                 check_irq_resend(desc, irq);
173                 /* fall-through */
174         }
175         default:
176                 desc->depth--;
177         }
178 }
179
180 /**
181  *      enable_irq - enable handling of an irq
182  *      @irq: Interrupt to enable
183  *
184  *      Undoes the effect of one call to disable_irq().  If this
185  *      matches the last disable, processing of interrupts on this
186  *      IRQ line is re-enabled.
187  *
188  *      This function may be called from IRQ context.
189  */
190 void enable_irq(unsigned int irq)
191 {
192         struct irq_desc *desc = irq_desc + irq;
193         unsigned long flags;
194
195         if (irq >= NR_IRQS)
196                 return;
197
198         spin_lock_irqsave(&desc->lock, flags);
199         __enable_irq(desc, irq);
200         spin_unlock_irqrestore(&desc->lock, flags);
201 }
202 EXPORT_SYMBOL(enable_irq);
203
204 /**
205  *      set_irq_wake - control irq power management wakeup
206  *      @irq:   interrupt to control
207  *      @on:    enable/disable power management wakeup
208  *
209  *      Enable/disable power management wakeup mode, which is
210  *      disabled by default.  Enables and disables must match,
211  *      just as they match for non-wakeup mode support.
212  *
213  *      Wakeup mode lets this IRQ wake the system from sleep
214  *      states like "suspend to RAM".
215  */
216 int set_irq_wake(unsigned int irq, unsigned int on)
217 {
218         struct irq_desc *desc = irq_desc + irq;
219         unsigned long flags;
220         int ret = -ENXIO;
221         int (*set_wake)(unsigned, unsigned) = desc->chip->set_wake;
222
223         /* wakeup-capable irqs can be shared between drivers that
224          * don't need to have the same sleep mode behaviors.
225          */
226         spin_lock_irqsave(&desc->lock, flags);
227         if (on) {
228                 if (desc->wake_depth++ == 0)
229                         desc->status |= IRQ_WAKEUP;
230                 else
231                         set_wake = NULL;
232         } else {
233                 if (desc->wake_depth == 0) {
234                         printk(KERN_WARNING "Unbalanced IRQ %d "
235                                         "wake disable\n", irq);
236                         WARN_ON(1);
237                 } else if (--desc->wake_depth == 0)
238                         desc->status &= ~IRQ_WAKEUP;
239                 else
240                         set_wake = NULL;
241         }
242         if (set_wake)
243                 ret = desc->chip->set_wake(irq, on);
244         spin_unlock_irqrestore(&desc->lock, flags);
245         return ret;
246 }
247 EXPORT_SYMBOL(set_irq_wake);
248
249 /*
250  * Internal function that tells the architecture code whether a
251  * particular irq has been exclusively allocated or is available
252  * for driver use.
253  */
254 int can_request_irq(unsigned int irq, unsigned long irqflags)
255 {
256         struct irqaction *action;
257
258         if (irq >= NR_IRQS || irq_desc[irq].status & IRQ_NOREQUEST)
259                 return 0;
260
261         action = irq_desc[irq].action;
262         if (action)
263                 if (irqflags & action->flags & IRQF_SHARED)
264                         action = NULL;
265
266         return !action;
267 }
268
269 void compat_irq_chip_set_default_handler(struct irq_desc *desc)
270 {
271         /*
272          * If the architecture still has not overriden
273          * the flow handler then zap the default. This
274          * should catch incorrect flow-type setting.
275          */
276         if (desc->handle_irq == &handle_bad_irq)
277                 desc->handle_irq = NULL;
278 }
279
280 /*
281  * Internal function to register an irqaction - typically used to
282  * allocate special interrupts that are part of the architecture.
283  */
284 int setup_irq(unsigned int irq, struct irqaction *new)
285 {
286         struct irq_desc *desc = irq_desc + irq;
287         struct irqaction *old, **p;
288         const char *old_name = NULL;
289         unsigned long flags;
290         int shared = 0;
291
292         if (irq >= NR_IRQS)
293                 return -EINVAL;
294
295         if (desc->chip == &no_irq_chip)
296                 return -ENOSYS;
297         /*
298          * Some drivers like serial.c use request_irq() heavily,
299          * so we have to be careful not to interfere with a
300          * running system.
301          */
302         if (new->flags & IRQF_SAMPLE_RANDOM) {
303                 /*
304                  * This function might sleep, we want to call it first,
305                  * outside of the atomic block.
306                  * Yes, this might clear the entropy pool if the wrong
307                  * driver is attempted to be loaded, without actually
308                  * installing a new handler, but is this really a problem,
309                  * only the sysadmin is able to do this.
310                  */
311                 rand_initialize_irq(irq);
312         }
313
314         /*
315          * The following block of code has to be executed atomically
316          */
317         spin_lock_irqsave(&desc->lock, flags);
318         p = &desc->action;
319         old = *p;
320         if (old) {
321                 /*
322                  * Can't share interrupts unless both agree to and are
323                  * the same type (level, edge, polarity). So both flag
324                  * fields must have IRQF_SHARED set and the bits which
325                  * set the trigger type must match.
326                  */
327                 if (!((old->flags & new->flags) & IRQF_SHARED) ||
328                     ((old->flags ^ new->flags) & IRQF_TRIGGER_MASK)) {
329                         old_name = old->name;
330                         goto mismatch;
331                 }
332
333 #if defined(CONFIG_IRQ_PER_CPU)
334                 /* All handlers must agree on per-cpuness */
335                 if ((old->flags & IRQF_PERCPU) !=
336                     (new->flags & IRQF_PERCPU))
337                         goto mismatch;
338 #endif
339
340                 /* add new interrupt at end of irq queue */
341                 do {
342                         p = &old->next;
343                         old = *p;
344                 } while (old);
345                 shared = 1;
346         }
347
348         *p = new;
349
350         /* Exclude IRQ from balancing */
351         if (new->flags & IRQF_NOBALANCING)
352                 desc->status |= IRQ_NO_BALANCING;
353
354         if (!shared) {
355                 irq_chip_set_defaults(desc->chip);
356
357 #if defined(CONFIG_IRQ_PER_CPU)
358                 if (new->flags & IRQF_PERCPU)
359                         desc->status |= IRQ_PER_CPU;
360 #endif
361
362                 /* Setup the type (level, edge polarity) if configured: */
363                 if (new->flags & IRQF_TRIGGER_MASK) {
364                         if (desc->chip && desc->chip->set_type)
365                                 desc->chip->set_type(irq,
366                                                 new->flags & IRQF_TRIGGER_MASK);
367                         else
368                                 /*
369                                  * IRQF_TRIGGER_* but the PIC does not support
370                                  * multiple flow-types?
371                                  */
372                                 printk(KERN_WARNING "No IRQF_TRIGGER set_type "
373                                        "function for IRQ %d (%s)\n", irq,
374                                        desc->chip ? desc->chip->name :
375                                        "unknown");
376                 } else
377                         compat_irq_chip_set_default_handler(desc);
378
379                 desc->status &= ~(IRQ_AUTODETECT | IRQ_WAITING |
380                                   IRQ_INPROGRESS | IRQ_SPURIOUS_DISABLED);
381
382                 if (!(desc->status & IRQ_NOAUTOEN)) {
383                         desc->depth = 0;
384                         desc->status &= ~IRQ_DISABLED;
385                         if (desc->chip->startup)
386                                 desc->chip->startup(irq);
387                         else
388                                 desc->chip->enable(irq);
389                 } else
390                         /* Undo nested disables: */
391                         desc->depth = 1;
392         }
393         /* Reset broken irq detection when installing new handler */
394         desc->irq_count = 0;
395         desc->irqs_unhandled = 0;
396
397         /*
398          * Check whether we disabled the irq via the spurious handler
399          * before. Reenable it and give it another chance.
400          */
401         if (shared && (desc->status & IRQ_SPURIOUS_DISABLED)) {
402                 desc->status &= ~IRQ_SPURIOUS_DISABLED;
403                 __enable_irq(desc, irq);
404         }
405
406         spin_unlock_irqrestore(&desc->lock, flags);
407
408         new->irq = irq;
409         register_irq_proc(irq);
410         new->dir = NULL;
411         register_handler_proc(irq, new);
412
413         return 0;
414
415 mismatch:
416 #ifdef CONFIG_DEBUG_SHIRQ
417         if (!(new->flags & IRQF_PROBE_SHARED)) {
418                 printk(KERN_ERR "IRQ handler type mismatch for IRQ %d\n", irq);
419                 if (old_name)
420                         printk(KERN_ERR "current handler: %s\n", old_name);
421                 dump_stack();
422         }
423 #endif
424         spin_unlock_irqrestore(&desc->lock, flags);
425         return -EBUSY;
426 }
427
428 /**
429  *      free_irq - free an interrupt
430  *      @irq: Interrupt line to free
431  *      @dev_id: Device identity to free
432  *
433  *      Remove an interrupt handler. The handler is removed and if the
434  *      interrupt line is no longer in use by any driver it is disabled.
435  *      On a shared IRQ the caller must ensure the interrupt is disabled
436  *      on the card it drives before calling this function. The function
437  *      does not return until any executing interrupts for this IRQ
438  *      have completed.
439  *
440  *      This function must not be called from interrupt context.
441  */
442 void free_irq(unsigned int irq, void *dev_id)
443 {
444         struct irq_desc *desc;
445         struct irqaction **p;
446         unsigned long flags;
447
448         WARN_ON(in_interrupt());
449         if (irq >= NR_IRQS)
450                 return;
451
452         desc = irq_desc + irq;
453         spin_lock_irqsave(&desc->lock, flags);
454         p = &desc->action;
455         for (;;) {
456                 struct irqaction *action = *p;
457
458                 if (action) {
459                         struct irqaction **pp = p;
460
461                         p = &action->next;
462                         if (action->dev_id != dev_id)
463                                 continue;
464
465                         /* Found it - now remove it from the list of entries */
466                         *pp = action->next;
467
468                         /* Currently used only by UML, might disappear one day.*/
469 #ifdef CONFIG_IRQ_RELEASE_METHOD
470                         if (desc->chip->release)
471                                 desc->chip->release(irq, dev_id);
472 #endif
473
474                         if (!desc->action) {
475                                 desc->status |= IRQ_DISABLED;
476                                 if (desc->chip->shutdown)
477                                         desc->chip->shutdown(irq);
478                                 else
479                                         desc->chip->disable(irq);
480                         }
481                         spin_unlock_irqrestore(&desc->lock, flags);
482                         unregister_handler_proc(irq, action);
483
484                         /* Make sure it's not being used on another CPU */
485                         synchronize_irq(irq);
486 #ifdef CONFIG_DEBUG_SHIRQ
487                         /*
488                          * It's a shared IRQ -- the driver ought to be
489                          * prepared for it to happen even now it's
490                          * being freed, so let's make sure....  We do
491                          * this after actually deregistering it, to
492                          * make sure that a 'real' IRQ doesn't run in
493                          * parallel with our fake
494                          */
495                         if (action->flags & IRQF_SHARED) {
496                                 local_irq_save(flags);
497                                 action->handler(irq, dev_id);
498                                 local_irq_restore(flags);
499                         }
500 #endif
501                         kfree(action);
502                         return;
503                 }
504                 printk(KERN_ERR "Trying to free already-free IRQ %d\n", irq);
505 #ifdef CONFIG_DEBUG_SHIRQ
506                 dump_stack();
507 #endif
508                 spin_unlock_irqrestore(&desc->lock, flags);
509                 return;
510         }
511 }
512 EXPORT_SYMBOL(free_irq);
513
514 /**
515  *      request_irq - allocate an interrupt line
516  *      @irq: Interrupt line to allocate
517  *      @handler: Function to be called when the IRQ occurs
518  *      @irqflags: Interrupt type flags
519  *      @devname: An ascii name for the claiming device
520  *      @dev_id: A cookie passed back to the handler function
521  *
522  *      This call allocates interrupt resources and enables the
523  *      interrupt line and IRQ handling. From the point this
524  *      call is made your handler function may be invoked. Since
525  *      your handler function must clear any interrupt the board
526  *      raises, you must take care both to initialise your hardware
527  *      and to set up the interrupt handler in the right order.
528  *
529  *      Dev_id must be globally unique. Normally the address of the
530  *      device data structure is used as the cookie. Since the handler
531  *      receives this value it makes sense to use it.
532  *
533  *      If your interrupt is shared you must pass a non NULL dev_id
534  *      as this is required when freeing the interrupt.
535  *
536  *      Flags:
537  *
538  *      IRQF_SHARED             Interrupt is shared
539  *      IRQF_DISABLED   Disable local interrupts while processing
540  *      IRQF_SAMPLE_RANDOM      The interrupt can be used for entropy
541  *
542  */
543 int request_irq(unsigned int irq, irq_handler_t handler,
544                 unsigned long irqflags, const char *devname, void *dev_id)
545 {
546         struct irqaction *action;
547         int retval;
548
549 #ifdef CONFIG_LOCKDEP
550         /*
551          * Lockdep wants atomic interrupt handlers:
552          */
553         irqflags |= IRQF_DISABLED;
554 #endif
555         /*
556          * Sanity-check: shared interrupts must pass in a real dev-ID,
557          * otherwise we'll have trouble later trying to figure out
558          * which interrupt is which (messes up the interrupt freeing
559          * logic etc).
560          */
561         if ((irqflags & IRQF_SHARED) && !dev_id)
562                 return -EINVAL;
563         if (irq >= NR_IRQS)
564                 return -EINVAL;
565         if (irq_desc[irq].status & IRQ_NOREQUEST)
566                 return -EINVAL;
567         if (!handler)
568                 return -EINVAL;
569
570         action = kmalloc(sizeof(struct irqaction), GFP_ATOMIC);
571         if (!action)
572                 return -ENOMEM;
573
574         action->handler = handler;
575         action->flags = irqflags;
576         cpus_clear(action->mask);
577         action->name = devname;
578         action->next = NULL;
579         action->dev_id = dev_id;
580
581         select_smp_affinity(irq);
582
583 #ifdef CONFIG_DEBUG_SHIRQ
584         if (irqflags & IRQF_SHARED) {
585                 /*
586                  * It's a shared IRQ -- the driver ought to be prepared for it
587                  * to happen immediately, so let's make sure....
588                  * We do this before actually registering it, to make sure that
589                  * a 'real' IRQ doesn't run in parallel with our fake
590                  */
591                 unsigned long flags;
592
593                 local_irq_save(flags);
594                 handler(irq, dev_id);
595                 local_irq_restore(flags);
596         }
597 #endif
598
599         retval = setup_irq(irq, action);
600         if (retval)
601                 kfree(action);
602
603         return retval;
604 }
605 EXPORT_SYMBOL(request_irq);