genirq: Rremove redundant check
[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/kthread.h>
12 #include <linux/module.h>
13 #include <linux/random.h>
14 #include <linux/interrupt.h>
15 #include <linux/slab.h>
16 #include <linux/sched.h>
17
18 #include "internals.h"
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_to_desc(irq);
33         unsigned int status;
34
35         if (!desc)
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                 raw_spin_lock_irqsave(&desc->lock, flags);
50                 status = desc->status;
51                 raw_spin_unlock_irqrestore(&desc->lock, flags);
52
53                 /* Oops, that failed? */
54         } while (status & IRQ_INPROGRESS);
55
56         /*
57          * We made sure that no hardirq handler is running. Now verify
58          * that no threaded handlers are active.
59          */
60         wait_event(desc->wait_for_threads, !atomic_read(&desc->threads_active));
61 }
62 EXPORT_SYMBOL(synchronize_irq);
63
64 #ifdef CONFIG_SMP
65 cpumask_var_t irq_default_affinity;
66
67 /**
68  *      irq_can_set_affinity - Check if the affinity of a given irq can be set
69  *      @irq:           Interrupt to check
70  *
71  */
72 int irq_can_set_affinity(unsigned int irq)
73 {
74         struct irq_desc *desc = irq_to_desc(irq);
75
76         if (CHECK_IRQ_PER_CPU(desc->status) || !desc->irq_data.chip ||
77             !desc->irq_data.chip->irq_set_affinity)
78                 return 0;
79
80         return 1;
81 }
82
83 /**
84  *      irq_set_thread_affinity - Notify irq threads to adjust affinity
85  *      @desc:          irq descriptor which has affitnity changed
86  *
87  *      We just set IRQTF_AFFINITY and delegate the affinity setting
88  *      to the interrupt thread itself. We can not call
89  *      set_cpus_allowed_ptr() here as we hold desc->lock and this
90  *      code can be called from hard interrupt context.
91  */
92 void irq_set_thread_affinity(struct irq_desc *desc)
93 {
94         struct irqaction *action = desc->action;
95
96         while (action) {
97                 if (action->thread)
98                         set_bit(IRQTF_AFFINITY, &action->thread_flags);
99                 action = action->next;
100         }
101 }
102
103 #ifdef CONFIG_GENERIC_PENDING_IRQ
104 static inline bool irq_can_move_pcntxt(struct irq_desc *desc)
105 {
106         return desc->status & IRQ_MOVE_PCNTXT;
107 }
108 static inline bool irq_move_pending(struct irq_desc *desc)
109 {
110         return desc->status & IRQ_MOVE_PENDING;
111 }
112 static inline void
113 irq_copy_pending(struct irq_desc *desc, const struct cpumask *mask)
114 {
115         cpumask_copy(desc->pending_mask, mask);
116 }
117 static inline void
118 irq_get_pending(struct cpumask *mask, struct irq_desc *desc)
119 {
120         cpumask_copy(mask, desc->pending_mask);
121 }
122 #else
123 static inline bool irq_can_move_pcntxt(struct irq_desc *desc) { return true; }
124 static inline bool irq_move_pending(struct irq_desc *desc) { return false; }
125 static inline void
126 irq_copy_pending(struct irq_desc *desc, const struct cpumask *mask) { }
127 static inline void
128 irq_get_pending(struct cpumask *mask, struct irq_desc *desc) { }
129 #endif
130
131 /**
132  *      irq_set_affinity - Set the irq affinity of a given irq
133  *      @irq:           Interrupt to set affinity
134  *      @cpumask:       cpumask
135  *
136  */
137 int irq_set_affinity(unsigned int irq, const struct cpumask *mask)
138 {
139         struct irq_desc *desc = irq_to_desc(irq);
140         struct irq_chip *chip = desc->irq_data.chip;
141         unsigned long flags;
142         int ret = 0;
143
144         if (!chip->irq_set_affinity)
145                 return -EINVAL;
146
147         raw_spin_lock_irqsave(&desc->lock, flags);
148
149         if (irq_can_move_pcntxt(desc)) {
150                 ret = chip->irq_set_affinity(&desc->irq_data, mask, false);
151                 if (!ret) {
152                         cpumask_copy(desc->irq_data.affinity, mask);
153                         irq_set_thread_affinity(desc);
154                 }
155         } else {
156                 desc->status |= IRQ_MOVE_PENDING;
157                 irq_copy_pending(desc, mask);
158         }
159
160         if (desc->affinity_notify) {
161                 kref_get(&desc->affinity_notify->kref);
162                 schedule_work(&desc->affinity_notify->work);
163         }
164         desc->status |= IRQ_AFFINITY_SET;
165         raw_spin_unlock_irqrestore(&desc->lock, flags);
166         return ret;
167 }
168
169 int irq_set_affinity_hint(unsigned int irq, const struct cpumask *m)
170 {
171         struct irq_desc *desc = irq_to_desc(irq);
172         unsigned long flags;
173
174         if (!desc)
175                 return -EINVAL;
176
177         raw_spin_lock_irqsave(&desc->lock, flags);
178         desc->affinity_hint = m;
179         raw_spin_unlock_irqrestore(&desc->lock, flags);
180
181         return 0;
182 }
183 EXPORT_SYMBOL_GPL(irq_set_affinity_hint);
184
185 static void irq_affinity_notify(struct work_struct *work)
186 {
187         struct irq_affinity_notify *notify =
188                 container_of(work, struct irq_affinity_notify, work);
189         struct irq_desc *desc = irq_to_desc(notify->irq);
190         cpumask_var_t cpumask;
191         unsigned long flags;
192
193         if (!desc || !alloc_cpumask_var(&cpumask, GFP_KERNEL))
194                 goto out;
195
196         raw_spin_lock_irqsave(&desc->lock, flags);
197         if (irq_move_pending(desc))
198                 irq_get_pending(cpumask, desc);
199         else
200                 cpumask_copy(cpumask, desc->irq_data.affinity);
201         raw_spin_unlock_irqrestore(&desc->lock, flags);
202
203         notify->notify(notify, cpumask);
204
205         free_cpumask_var(cpumask);
206 out:
207         kref_put(&notify->kref, notify->release);
208 }
209
210 /**
211  *      irq_set_affinity_notifier - control notification of IRQ affinity changes
212  *      @irq:           Interrupt for which to enable/disable notification
213  *      @notify:        Context for notification, or %NULL to disable
214  *                      notification.  Function pointers must be initialised;
215  *                      the other fields will be initialised by this function.
216  *
217  *      Must be called in process context.  Notification may only be enabled
218  *      after the IRQ is allocated and must be disabled before the IRQ is
219  *      freed using free_irq().
220  */
221 int
222 irq_set_affinity_notifier(unsigned int irq, struct irq_affinity_notify *notify)
223 {
224         struct irq_desc *desc = irq_to_desc(irq);
225         struct irq_affinity_notify *old_notify;
226         unsigned long flags;
227
228         /* The release function is promised process context */
229         might_sleep();
230
231         if (!desc)
232                 return -EINVAL;
233
234         /* Complete initialisation of *notify */
235         if (notify) {
236                 notify->irq = irq;
237                 kref_init(&notify->kref);
238                 INIT_WORK(&notify->work, irq_affinity_notify);
239         }
240
241         raw_spin_lock_irqsave(&desc->lock, flags);
242         old_notify = desc->affinity_notify;
243         desc->affinity_notify = notify;
244         raw_spin_unlock_irqrestore(&desc->lock, flags);
245
246         if (old_notify)
247                 kref_put(&old_notify->kref, old_notify->release);
248
249         return 0;
250 }
251 EXPORT_SYMBOL_GPL(irq_set_affinity_notifier);
252
253 #ifndef CONFIG_AUTO_IRQ_AFFINITY
254 /*
255  * Generic version of the affinity autoselector.
256  */
257 static int setup_affinity(unsigned int irq, struct irq_desc *desc)
258 {
259         /* Excludes PER_CPU and NO_BALANCE interrupts */
260         if (!irq_can_set_affinity(irq))
261                 return 0;
262
263         /*
264          * Preserve an userspace affinity setup, but make sure that
265          * one of the targets is online.
266          */
267         if (desc->status & (IRQ_AFFINITY_SET)) {
268                 if (cpumask_any_and(desc->irq_data.affinity, cpu_online_mask)
269                     < nr_cpu_ids)
270                         goto set_affinity;
271                 else
272                         desc->status &= ~IRQ_AFFINITY_SET;
273         }
274
275         cpumask_and(desc->irq_data.affinity, cpu_online_mask, irq_default_affinity);
276 set_affinity:
277         desc->irq_data.chip->irq_set_affinity(&desc->irq_data, desc->irq_data.affinity, false);
278
279         return 0;
280 }
281 #else
282 static inline int setup_affinity(unsigned int irq, struct irq_desc *d)
283 {
284         return irq_select_affinity(irq);
285 }
286 #endif
287
288 /*
289  * Called when affinity is set via /proc/irq
290  */
291 int irq_select_affinity_usr(unsigned int irq)
292 {
293         struct irq_desc *desc = irq_to_desc(irq);
294         unsigned long flags;
295         int ret;
296
297         raw_spin_lock_irqsave(&desc->lock, flags);
298         ret = setup_affinity(irq, desc);
299         if (!ret)
300                 irq_set_thread_affinity(desc);
301         raw_spin_unlock_irqrestore(&desc->lock, flags);
302
303         return ret;
304 }
305
306 #else
307 static inline int setup_affinity(unsigned int irq, struct irq_desc *desc)
308 {
309         return 0;
310 }
311 #endif
312
313 void __disable_irq(struct irq_desc *desc, unsigned int irq, bool suspend)
314 {
315         if (suspend) {
316                 if (!desc->action || (desc->action->flags & IRQF_NO_SUSPEND))
317                         return;
318                 desc->status |= IRQ_SUSPENDED;
319         }
320
321         if (!desc->depth++) {
322                 desc->status |= IRQ_DISABLED;
323                 desc->irq_data.chip->irq_disable(&desc->irq_data);
324         }
325 }
326
327 /**
328  *      disable_irq_nosync - disable an irq without waiting
329  *      @irq: Interrupt to disable
330  *
331  *      Disable the selected interrupt line.  Disables and Enables are
332  *      nested.
333  *      Unlike disable_irq(), this function does not ensure existing
334  *      instances of the IRQ handler have completed before returning.
335  *
336  *      This function may be called from IRQ context.
337  */
338 void disable_irq_nosync(unsigned int irq)
339 {
340         struct irq_desc *desc = irq_to_desc(irq);
341         unsigned long flags;
342
343         if (!desc)
344                 return;
345
346         chip_bus_lock(desc);
347         raw_spin_lock_irqsave(&desc->lock, flags);
348         __disable_irq(desc, irq, false);
349         raw_spin_unlock_irqrestore(&desc->lock, flags);
350         chip_bus_sync_unlock(desc);
351 }
352 EXPORT_SYMBOL(disable_irq_nosync);
353
354 /**
355  *      disable_irq - disable an irq and wait for completion
356  *      @irq: Interrupt to disable
357  *
358  *      Disable the selected interrupt line.  Enables and Disables are
359  *      nested.
360  *      This function waits for any pending IRQ handlers for this interrupt
361  *      to complete before returning. If you use this function while
362  *      holding a resource the IRQ handler may need you will deadlock.
363  *
364  *      This function may be called - with care - from IRQ context.
365  */
366 void disable_irq(unsigned int irq)
367 {
368         struct irq_desc *desc = irq_to_desc(irq);
369
370         if (!desc)
371                 return;
372
373         disable_irq_nosync(irq);
374         if (desc->action)
375                 synchronize_irq(irq);
376 }
377 EXPORT_SYMBOL(disable_irq);
378
379 void __enable_irq(struct irq_desc *desc, unsigned int irq, bool resume)
380 {
381         if (resume) {
382                 if (!(desc->status & IRQ_SUSPENDED)) {
383                         if (!desc->action)
384                                 return;
385                         if (!(desc->action->flags & IRQF_FORCE_RESUME))
386                                 return;
387                         /* Pretend that it got disabled ! */
388                         desc->depth++;
389                 }
390                 desc->status &= ~IRQ_SUSPENDED;
391         }
392
393         switch (desc->depth) {
394         case 0:
395  err_out:
396                 WARN(1, KERN_WARNING "Unbalanced enable for IRQ %d\n", irq);
397                 break;
398         case 1: {
399                 unsigned int status = desc->status & ~IRQ_DISABLED;
400
401                 if (desc->status & IRQ_SUSPENDED)
402                         goto err_out;
403                 /* Prevent probing on this irq: */
404                 desc->status = status | IRQ_NOPROBE;
405                 check_irq_resend(desc, irq);
406                 /* fall-through */
407         }
408         default:
409                 desc->depth--;
410         }
411 }
412
413 /**
414  *      enable_irq - enable handling of an irq
415  *      @irq: Interrupt to enable
416  *
417  *      Undoes the effect of one call to disable_irq().  If this
418  *      matches the last disable, processing of interrupts on this
419  *      IRQ line is re-enabled.
420  *
421  *      This function may be called from IRQ context only when
422  *      desc->irq_data.chip->bus_lock and desc->chip->bus_sync_unlock are NULL !
423  */
424 void enable_irq(unsigned int irq)
425 {
426         struct irq_desc *desc = irq_to_desc(irq);
427         unsigned long flags;
428
429         if (!desc)
430                 return;
431
432         if (WARN(!desc->irq_data.chip || !desc->irq_data.chip->irq_enable,
433             KERN_ERR "enable_irq before setup/request_irq: irq %u\n", irq))
434                 return;
435
436         chip_bus_lock(desc);
437         raw_spin_lock_irqsave(&desc->lock, flags);
438         __enable_irq(desc, irq, false);
439         raw_spin_unlock_irqrestore(&desc->lock, flags);
440         chip_bus_sync_unlock(desc);
441 }
442 EXPORT_SYMBOL(enable_irq);
443
444 static int set_irq_wake_real(unsigned int irq, unsigned int on)
445 {
446         struct irq_desc *desc = irq_to_desc(irq);
447         int ret = -ENXIO;
448
449         if (desc->irq_data.chip->irq_set_wake)
450                 ret = desc->irq_data.chip->irq_set_wake(&desc->irq_data, on);
451
452         return ret;
453 }
454
455 /**
456  *      irq_set_irq_wake - control irq power management wakeup
457  *      @irq:   interrupt to control
458  *      @on:    enable/disable power management wakeup
459  *
460  *      Enable/disable power management wakeup mode, which is
461  *      disabled by default.  Enables and disables must match,
462  *      just as they match for non-wakeup mode support.
463  *
464  *      Wakeup mode lets this IRQ wake the system from sleep
465  *      states like "suspend to RAM".
466  */
467 int irq_set_irq_wake(unsigned int irq, unsigned int on)
468 {
469         struct irq_desc *desc = irq_to_desc(irq);
470         unsigned long flags;
471         int ret = 0;
472
473         /* wakeup-capable irqs can be shared between drivers that
474          * don't need to have the same sleep mode behaviors.
475          */
476         chip_bus_lock(desc);
477         raw_spin_lock_irqsave(&desc->lock, flags);
478         if (on) {
479                 if (desc->wake_depth++ == 0) {
480                         ret = set_irq_wake_real(irq, on);
481                         if (ret)
482                                 desc->wake_depth = 0;
483                         else
484                                 desc->status |= IRQ_WAKEUP;
485                 }
486         } else {
487                 if (desc->wake_depth == 0) {
488                         WARN(1, "Unbalanced IRQ %d wake disable\n", irq);
489                 } else if (--desc->wake_depth == 0) {
490                         ret = set_irq_wake_real(irq, on);
491                         if (ret)
492                                 desc->wake_depth = 1;
493                         else
494                                 desc->status &= ~IRQ_WAKEUP;
495                 }
496         }
497
498         raw_spin_unlock_irqrestore(&desc->lock, flags);
499         chip_bus_sync_unlock(desc);
500         return ret;
501 }
502 EXPORT_SYMBOL(irq_set_irq_wake);
503
504 /*
505  * Internal function that tells the architecture code whether a
506  * particular irq has been exclusively allocated or is available
507  * for driver use.
508  */
509 int can_request_irq(unsigned int irq, unsigned long irqflags)
510 {
511         struct irq_desc *desc = irq_to_desc(irq);
512         struct irqaction *action;
513         unsigned long flags;
514
515         if (!desc)
516                 return 0;
517
518         if (desc->status & IRQ_NOREQUEST)
519                 return 0;
520
521         raw_spin_lock_irqsave(&desc->lock, flags);
522         action = desc->action;
523         if (action)
524                 if (irqflags & action->flags & IRQF_SHARED)
525                         action = NULL;
526
527         raw_spin_unlock_irqrestore(&desc->lock, flags);
528
529         return !action;
530 }
531
532 void compat_irq_chip_set_default_handler(struct irq_desc *desc)
533 {
534         /*
535          * If the architecture still has not overriden
536          * the flow handler then zap the default. This
537          * should catch incorrect flow-type setting.
538          */
539         if (desc->handle_irq == &handle_bad_irq)
540                 desc->handle_irq = NULL;
541 }
542
543 int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
544                       unsigned long flags)
545 {
546         int ret;
547         struct irq_chip *chip = desc->irq_data.chip;
548
549         if (!chip || !chip->irq_set_type) {
550                 /*
551                  * IRQF_TRIGGER_* but the PIC does not support multiple
552                  * flow-types?
553                  */
554                 pr_debug("No set_type function for IRQ %d (%s)\n", irq,
555                                 chip ? (chip->name ? : "unknown") : "unknown");
556                 return 0;
557         }
558
559         /* caller masked out all except trigger mode flags */
560         ret = chip->irq_set_type(&desc->irq_data, flags);
561
562         if (ret)
563                 pr_err("setting trigger mode %lu for irq %u failed (%pF)\n",
564                        flags, irq, chip->irq_set_type);
565         else {
566                 if (flags & (IRQ_TYPE_LEVEL_LOW | IRQ_TYPE_LEVEL_HIGH))
567                         flags |= IRQ_LEVEL;
568                 /* note that IRQF_TRIGGER_MASK == IRQ_TYPE_SENSE_MASK */
569                 desc->status &= ~(IRQ_LEVEL | IRQ_TYPE_SENSE_MASK);
570                 desc->status |= flags;
571
572                 if (chip != desc->irq_data.chip)
573                         irq_chip_set_defaults(desc->irq_data.chip);
574         }
575
576         return ret;
577 }
578
579 /*
580  * Default primary interrupt handler for threaded interrupts. Is
581  * assigned as primary handler when request_threaded_irq is called
582  * with handler == NULL. Useful for oneshot interrupts.
583  */
584 static irqreturn_t irq_default_primary_handler(int irq, void *dev_id)
585 {
586         return IRQ_WAKE_THREAD;
587 }
588
589 /*
590  * Primary handler for nested threaded interrupts. Should never be
591  * called.
592  */
593 static irqreturn_t irq_nested_primary_handler(int irq, void *dev_id)
594 {
595         WARN(1, "Primary handler called for nested irq %d\n", irq);
596         return IRQ_NONE;
597 }
598
599 static int irq_wait_for_interrupt(struct irqaction *action)
600 {
601         while (!kthread_should_stop()) {
602                 set_current_state(TASK_INTERRUPTIBLE);
603
604                 if (test_and_clear_bit(IRQTF_RUNTHREAD,
605                                        &action->thread_flags)) {
606                         __set_current_state(TASK_RUNNING);
607                         return 0;
608                 }
609                 schedule();
610         }
611         return -1;
612 }
613
614 /*
615  * Oneshot interrupts keep the irq line masked until the threaded
616  * handler finished. unmask if the interrupt has not been disabled and
617  * is marked MASKED.
618  */
619 static void irq_finalize_oneshot(unsigned int irq, struct irq_desc *desc)
620 {
621 again:
622         chip_bus_lock(desc);
623         raw_spin_lock_irq(&desc->lock);
624
625         /*
626          * Implausible though it may be we need to protect us against
627          * the following scenario:
628          *
629          * The thread is faster done than the hard interrupt handler
630          * on the other CPU. If we unmask the irq line then the
631          * interrupt can come in again and masks the line, leaves due
632          * to IRQ_INPROGRESS and the irq line is masked forever.
633          */
634         if (unlikely(desc->status & IRQ_INPROGRESS)) {
635                 raw_spin_unlock_irq(&desc->lock);
636                 chip_bus_sync_unlock(desc);
637                 cpu_relax();
638                 goto again;
639         }
640
641         if (!(desc->status & IRQ_DISABLED) && (desc->status & IRQ_MASKED)) {
642                 desc->status &= ~IRQ_MASKED;
643                 desc->irq_data.chip->irq_unmask(&desc->irq_data);
644         }
645         raw_spin_unlock_irq(&desc->lock);
646         chip_bus_sync_unlock(desc);
647 }
648
649 #ifdef CONFIG_SMP
650 /*
651  * Check whether we need to change the affinity of the interrupt thread.
652  */
653 static void
654 irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action)
655 {
656         cpumask_var_t mask;
657
658         if (!test_and_clear_bit(IRQTF_AFFINITY, &action->thread_flags))
659                 return;
660
661         /*
662          * In case we are out of memory we set IRQTF_AFFINITY again and
663          * try again next time
664          */
665         if (!alloc_cpumask_var(&mask, GFP_KERNEL)) {
666                 set_bit(IRQTF_AFFINITY, &action->thread_flags);
667                 return;
668         }
669
670         raw_spin_lock_irq(&desc->lock);
671         cpumask_copy(mask, desc->irq_data.affinity);
672         raw_spin_unlock_irq(&desc->lock);
673
674         set_cpus_allowed_ptr(current, mask);
675         free_cpumask_var(mask);
676 }
677 #else
678 static inline void
679 irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action) { }
680 #endif
681
682 /*
683  * Interrupt handler thread
684  */
685 static int irq_thread(void *data)
686 {
687         static const struct sched_param param = {
688                 .sched_priority = MAX_USER_RT_PRIO/2,
689         };
690         struct irqaction *action = data;
691         struct irq_desc *desc = irq_to_desc(action->irq);
692         int wake, oneshot = desc->status & IRQ_ONESHOT;
693
694         sched_setscheduler(current, SCHED_FIFO, &param);
695         current->irqaction = action;
696
697         while (!irq_wait_for_interrupt(action)) {
698
699                 irq_thread_check_affinity(desc, action);
700
701                 atomic_inc(&desc->threads_active);
702
703                 raw_spin_lock_irq(&desc->lock);
704                 if (unlikely(desc->status & IRQ_DISABLED)) {
705                         /*
706                          * CHECKME: We might need a dedicated
707                          * IRQ_THREAD_PENDING flag here, which
708                          * retriggers the thread in check_irq_resend()
709                          * but AFAICT IRQ_PENDING should be fine as it
710                          * retriggers the interrupt itself --- tglx
711                          */
712                         desc->status |= IRQ_PENDING;
713                         raw_spin_unlock_irq(&desc->lock);
714                 } else {
715                         raw_spin_unlock_irq(&desc->lock);
716
717                         action->thread_fn(action->irq, action->dev_id);
718
719                         if (oneshot)
720                                 irq_finalize_oneshot(action->irq, desc);
721                 }
722
723                 wake = atomic_dec_and_test(&desc->threads_active);
724
725                 if (wake && waitqueue_active(&desc->wait_for_threads))
726                         wake_up(&desc->wait_for_threads);
727         }
728
729         /*
730          * Clear irqaction. Otherwise exit_irq_thread() would make
731          * fuzz about an active irq thread going into nirvana.
732          */
733         current->irqaction = NULL;
734         return 0;
735 }
736
737 /*
738  * Called from do_exit()
739  */
740 void exit_irq_thread(void)
741 {
742         struct task_struct *tsk = current;
743
744         if (!tsk->irqaction)
745                 return;
746
747         printk(KERN_ERR
748                "exiting task \"%s\" (%d) is an active IRQ thread (irq %d)\n",
749                tsk->comm ? tsk->comm : "", tsk->pid, tsk->irqaction->irq);
750
751         /*
752          * Set the THREAD DIED flag to prevent further wakeups of the
753          * soon to be gone threaded handler.
754          */
755         set_bit(IRQTF_DIED, &tsk->irqaction->flags);
756 }
757
758 /*
759  * Internal function to register an irqaction - typically used to
760  * allocate special interrupts that are part of the architecture.
761  */
762 static int
763 __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
764 {
765         struct irqaction *old, **old_ptr;
766         const char *old_name = NULL;
767         unsigned long flags;
768         int nested, shared = 0;
769         int ret;
770
771         if (!desc)
772                 return -EINVAL;
773
774         if (desc->irq_data.chip == &no_irq_chip)
775                 return -ENOSYS;
776         /*
777          * Some drivers like serial.c use request_irq() heavily,
778          * so we have to be careful not to interfere with a
779          * running system.
780          */
781         if (new->flags & IRQF_SAMPLE_RANDOM) {
782                 /*
783                  * This function might sleep, we want to call it first,
784                  * outside of the atomic block.
785                  * Yes, this might clear the entropy pool if the wrong
786                  * driver is attempted to be loaded, without actually
787                  * installing a new handler, but is this really a problem,
788                  * only the sysadmin is able to do this.
789                  */
790                 rand_initialize_irq(irq);
791         }
792
793         /* Oneshot interrupts are not allowed with shared */
794         if ((new->flags & IRQF_ONESHOT) && (new->flags & IRQF_SHARED))
795                 return -EINVAL;
796
797         /*
798          * Check whether the interrupt nests into another interrupt
799          * thread.
800          */
801         nested = desc->status & IRQ_NESTED_THREAD;
802         if (nested) {
803                 if (!new->thread_fn)
804                         return -EINVAL;
805                 /*
806                  * Replace the primary handler which was provided from
807                  * the driver for non nested interrupt handling by the
808                  * dummy function which warns when called.
809                  */
810                 new->handler = irq_nested_primary_handler;
811         }
812
813         /*
814          * Create a handler thread when a thread function is supplied
815          * and the interrupt does not nest into another interrupt
816          * thread.
817          */
818         if (new->thread_fn && !nested) {
819                 struct task_struct *t;
820
821                 t = kthread_create(irq_thread, new, "irq/%d-%s", irq,
822                                    new->name);
823                 if (IS_ERR(t))
824                         return PTR_ERR(t);
825                 /*
826                  * We keep the reference to the task struct even if
827                  * the thread dies to avoid that the interrupt code
828                  * references an already freed task_struct.
829                  */
830                 get_task_struct(t);
831                 new->thread = t;
832         }
833
834         /*
835          * The following block of code has to be executed atomically
836          */
837         raw_spin_lock_irqsave(&desc->lock, flags);
838         old_ptr = &desc->action;
839         old = *old_ptr;
840         if (old) {
841                 /*
842                  * Can't share interrupts unless both agree to and are
843                  * the same type (level, edge, polarity). So both flag
844                  * fields must have IRQF_SHARED set and the bits which
845                  * set the trigger type must match.
846                  */
847                 if (!((old->flags & new->flags) & IRQF_SHARED) ||
848                     ((old->flags ^ new->flags) & IRQF_TRIGGER_MASK)) {
849                         old_name = old->name;
850                         goto mismatch;
851                 }
852
853 #if defined(CONFIG_IRQ_PER_CPU)
854                 /* All handlers must agree on per-cpuness */
855                 if ((old->flags & IRQF_PERCPU) !=
856                     (new->flags & IRQF_PERCPU))
857                         goto mismatch;
858 #endif
859
860                 /* add new interrupt at end of irq queue */
861                 do {
862                         old_ptr = &old->next;
863                         old = *old_ptr;
864                 } while (old);
865                 shared = 1;
866         }
867
868         if (!shared) {
869                 irq_chip_set_defaults(desc->irq_data.chip);
870
871                 init_waitqueue_head(&desc->wait_for_threads);
872
873                 /* Setup the type (level, edge polarity) if configured: */
874                 if (new->flags & IRQF_TRIGGER_MASK) {
875                         ret = __irq_set_trigger(desc, irq,
876                                         new->flags & IRQF_TRIGGER_MASK);
877
878                         if (ret)
879                                 goto out_thread;
880                 } else
881                         compat_irq_chip_set_default_handler(desc);
882 #if defined(CONFIG_IRQ_PER_CPU)
883                 if (new->flags & IRQF_PERCPU)
884                         desc->status |= IRQ_PER_CPU;
885 #endif
886
887                 desc->status &= ~(IRQ_AUTODETECT | IRQ_WAITING | IRQ_ONESHOT |
888                                   IRQ_INPROGRESS | IRQ_SPURIOUS_DISABLED);
889
890                 if (new->flags & IRQF_ONESHOT)
891                         desc->status |= IRQ_ONESHOT;
892
893                 if (!(desc->status & IRQ_NOAUTOEN)) {
894                         desc->depth = 0;
895                         desc->status &= ~IRQ_DISABLED;
896                         desc->irq_data.chip->irq_startup(&desc->irq_data);
897                 } else
898                         /* Undo nested disables: */
899                         desc->depth = 1;
900
901                 /* Exclude IRQ from balancing if requested */
902                 if (new->flags & IRQF_NOBALANCING)
903                         desc->status |= IRQ_NO_BALANCING;
904
905                 /* Set default affinity mask once everything is setup */
906                 setup_affinity(irq, desc);
907
908         } else if ((new->flags & IRQF_TRIGGER_MASK)
909                         && (new->flags & IRQF_TRIGGER_MASK)
910                                 != (desc->status & IRQ_TYPE_SENSE_MASK)) {
911                 /* hope the handler works with the actual trigger mode... */
912                 pr_warning("IRQ %d uses trigger mode %d; requested %d\n",
913                                 irq, (int)(desc->status & IRQ_TYPE_SENSE_MASK),
914                                 (int)(new->flags & IRQF_TRIGGER_MASK));
915         }
916
917         new->irq = irq;
918         *old_ptr = new;
919
920         /* Reset broken irq detection when installing new handler */
921         desc->irq_count = 0;
922         desc->irqs_unhandled = 0;
923
924         /*
925          * Check whether we disabled the irq via the spurious handler
926          * before. Reenable it and give it another chance.
927          */
928         if (shared && (desc->status & IRQ_SPURIOUS_DISABLED)) {
929                 desc->status &= ~IRQ_SPURIOUS_DISABLED;
930                 __enable_irq(desc, irq, false);
931         }
932
933         raw_spin_unlock_irqrestore(&desc->lock, flags);
934
935         /*
936          * Strictly no need to wake it up, but hung_task complains
937          * when no hard interrupt wakes the thread up.
938          */
939         if (new->thread)
940                 wake_up_process(new->thread);
941
942         register_irq_proc(irq, desc);
943         new->dir = NULL;
944         register_handler_proc(irq, new);
945
946         return 0;
947
948 mismatch:
949 #ifdef CONFIG_DEBUG_SHIRQ
950         if (!(new->flags & IRQF_PROBE_SHARED)) {
951                 printk(KERN_ERR "IRQ handler type mismatch for IRQ %d\n", irq);
952                 if (old_name)
953                         printk(KERN_ERR "current handler: %s\n", old_name);
954                 dump_stack();
955         }
956 #endif
957         ret = -EBUSY;
958
959 out_thread:
960         raw_spin_unlock_irqrestore(&desc->lock, flags);
961         if (new->thread) {
962                 struct task_struct *t = new->thread;
963
964                 new->thread = NULL;
965                 if (likely(!test_bit(IRQTF_DIED, &new->thread_flags)))
966                         kthread_stop(t);
967                 put_task_struct(t);
968         }
969         return ret;
970 }
971
972 /**
973  *      setup_irq - setup an interrupt
974  *      @irq: Interrupt line to setup
975  *      @act: irqaction for the interrupt
976  *
977  * Used to statically setup interrupts in the early boot process.
978  */
979 int setup_irq(unsigned int irq, struct irqaction *act)
980 {
981         int retval;
982         struct irq_desc *desc = irq_to_desc(irq);
983
984         chip_bus_lock(desc);
985         retval = __setup_irq(irq, desc, act);
986         chip_bus_sync_unlock(desc);
987
988         return retval;
989 }
990 EXPORT_SYMBOL_GPL(setup_irq);
991
992  /*
993  * Internal function to unregister an irqaction - used to free
994  * regular and special interrupts that are part of the architecture.
995  */
996 static struct irqaction *__free_irq(unsigned int irq, void *dev_id)
997 {
998         struct irq_desc *desc = irq_to_desc(irq);
999         struct irqaction *action, **action_ptr;
1000         unsigned long flags;
1001
1002         WARN(in_interrupt(), "Trying to free IRQ %d from IRQ context!\n", irq);
1003
1004         if (!desc)
1005                 return NULL;
1006
1007         raw_spin_lock_irqsave(&desc->lock, flags);
1008
1009         /*
1010          * There can be multiple actions per IRQ descriptor, find the right
1011          * one based on the dev_id:
1012          */
1013         action_ptr = &desc->action;
1014         for (;;) {
1015                 action = *action_ptr;
1016
1017                 if (!action) {
1018                         WARN(1, "Trying to free already-free IRQ %d\n", irq);
1019                         raw_spin_unlock_irqrestore(&desc->lock, flags);
1020
1021                         return NULL;
1022                 }
1023
1024                 if (action->dev_id == dev_id)
1025                         break;
1026                 action_ptr = &action->next;
1027         }
1028
1029         /* Found it - now remove it from the list of entries: */
1030         *action_ptr = action->next;
1031
1032         /* Currently used only by UML, might disappear one day: */
1033 #ifdef CONFIG_IRQ_RELEASE_METHOD
1034         if (desc->irq_data.chip->release)
1035                 desc->irq_data.chip->release(irq, dev_id);
1036 #endif
1037
1038         /* If this was the last handler, shut down the IRQ line: */
1039         if (!desc->action) {
1040                 desc->status |= IRQ_DISABLED;
1041                 if (desc->irq_data.chip->irq_shutdown)
1042                         desc->irq_data.chip->irq_shutdown(&desc->irq_data);
1043                 else
1044                         desc->irq_data.chip->irq_disable(&desc->irq_data);
1045         }
1046
1047 #ifdef CONFIG_SMP
1048         /* make sure affinity_hint is cleaned up */
1049         if (WARN_ON_ONCE(desc->affinity_hint))
1050                 desc->affinity_hint = NULL;
1051 #endif
1052
1053         raw_spin_unlock_irqrestore(&desc->lock, flags);
1054
1055         unregister_handler_proc(irq, action);
1056
1057         /* Make sure it's not being used on another CPU: */
1058         synchronize_irq(irq);
1059
1060 #ifdef CONFIG_DEBUG_SHIRQ
1061         /*
1062          * It's a shared IRQ -- the driver ought to be prepared for an IRQ
1063          * event to happen even now it's being freed, so let's make sure that
1064          * is so by doing an extra call to the handler ....
1065          *
1066          * ( We do this after actually deregistering it, to make sure that a
1067          *   'real' IRQ doesn't run in * parallel with our fake. )
1068          */
1069         if (action->flags & IRQF_SHARED) {
1070                 local_irq_save(flags);
1071                 action->handler(irq, dev_id);
1072                 local_irq_restore(flags);
1073         }
1074 #endif
1075
1076         if (action->thread) {
1077                 if (!test_bit(IRQTF_DIED, &action->thread_flags))
1078                         kthread_stop(action->thread);
1079                 put_task_struct(action->thread);
1080         }
1081
1082         return action;
1083 }
1084
1085 /**
1086  *      remove_irq - free an interrupt
1087  *      @irq: Interrupt line to free
1088  *      @act: irqaction for the interrupt
1089  *
1090  * Used to remove interrupts statically setup by the early boot process.
1091  */
1092 void remove_irq(unsigned int irq, struct irqaction *act)
1093 {
1094         __free_irq(irq, act->dev_id);
1095 }
1096 EXPORT_SYMBOL_GPL(remove_irq);
1097
1098 /**
1099  *      free_irq - free an interrupt allocated with request_irq
1100  *      @irq: Interrupt line to free
1101  *      @dev_id: Device identity to free
1102  *
1103  *      Remove an interrupt handler. The handler is removed and if the
1104  *      interrupt line is no longer in use by any driver it is disabled.
1105  *      On a shared IRQ the caller must ensure the interrupt is disabled
1106  *      on the card it drives before calling this function. The function
1107  *      does not return until any executing interrupts for this IRQ
1108  *      have completed.
1109  *
1110  *      This function must not be called from interrupt context.
1111  */
1112 void free_irq(unsigned int irq, void *dev_id)
1113 {
1114         struct irq_desc *desc = irq_to_desc(irq);
1115
1116         if (!desc)
1117                 return;
1118
1119 #ifdef CONFIG_SMP
1120         if (WARN_ON(desc->affinity_notify))
1121                 desc->affinity_notify = NULL;
1122 #endif
1123
1124         chip_bus_lock(desc);
1125         kfree(__free_irq(irq, dev_id));
1126         chip_bus_sync_unlock(desc);
1127 }
1128 EXPORT_SYMBOL(free_irq);
1129
1130 /**
1131  *      request_threaded_irq - allocate an interrupt line
1132  *      @irq: Interrupt line to allocate
1133  *      @handler: Function to be called when the IRQ occurs.
1134  *                Primary handler for threaded interrupts
1135  *                If NULL and thread_fn != NULL the default
1136  *                primary handler is installed
1137  *      @thread_fn: Function called from the irq handler thread
1138  *                  If NULL, no irq thread is created
1139  *      @irqflags: Interrupt type flags
1140  *      @devname: An ascii name for the claiming device
1141  *      @dev_id: A cookie passed back to the handler function
1142  *
1143  *      This call allocates interrupt resources and enables the
1144  *      interrupt line and IRQ handling. From the point this
1145  *      call is made your handler function may be invoked. Since
1146  *      your handler function must clear any interrupt the board
1147  *      raises, you must take care both to initialise your hardware
1148  *      and to set up the interrupt handler in the right order.
1149  *
1150  *      If you want to set up a threaded irq handler for your device
1151  *      then you need to supply @handler and @thread_fn. @handler ist
1152  *      still called in hard interrupt context and has to check
1153  *      whether the interrupt originates from the device. If yes it
1154  *      needs to disable the interrupt on the device and return
1155  *      IRQ_WAKE_THREAD which will wake up the handler thread and run
1156  *      @thread_fn. This split handler design is necessary to support
1157  *      shared interrupts.
1158  *
1159  *      Dev_id must be globally unique. Normally the address of the
1160  *      device data structure is used as the cookie. Since the handler
1161  *      receives this value it makes sense to use it.
1162  *
1163  *      If your interrupt is shared you must pass a non NULL dev_id
1164  *      as this is required when freeing the interrupt.
1165  *
1166  *      Flags:
1167  *
1168  *      IRQF_SHARED             Interrupt is shared
1169  *      IRQF_SAMPLE_RANDOM      The interrupt can be used for entropy
1170  *      IRQF_TRIGGER_*          Specify active edge(s) or level
1171  *
1172  */
1173 int request_threaded_irq(unsigned int irq, irq_handler_t handler,
1174                          irq_handler_t thread_fn, unsigned long irqflags,
1175                          const char *devname, void *dev_id)
1176 {
1177         struct irqaction *action;
1178         struct irq_desc *desc;
1179         int retval;
1180
1181         /*
1182          * Sanity-check: shared interrupts must pass in a real dev-ID,
1183          * otherwise we'll have trouble later trying to figure out
1184          * which interrupt is which (messes up the interrupt freeing
1185          * logic etc).
1186          */
1187         if ((irqflags & IRQF_SHARED) && !dev_id)
1188                 return -EINVAL;
1189
1190         desc = irq_to_desc(irq);
1191         if (!desc)
1192                 return -EINVAL;
1193
1194         if (desc->status & IRQ_NOREQUEST)
1195                 return -EINVAL;
1196
1197         if (!handler) {
1198                 if (!thread_fn)
1199                         return -EINVAL;
1200                 handler = irq_default_primary_handler;
1201         }
1202
1203         action = kzalloc(sizeof(struct irqaction), GFP_KERNEL);
1204         if (!action)
1205                 return -ENOMEM;
1206
1207         action->handler = handler;
1208         action->thread_fn = thread_fn;
1209         action->flags = irqflags;
1210         action->name = devname;
1211         action->dev_id = dev_id;
1212
1213         chip_bus_lock(desc);
1214         retval = __setup_irq(irq, desc, action);
1215         chip_bus_sync_unlock(desc);
1216
1217         if (retval)
1218                 kfree(action);
1219
1220 #ifdef CONFIG_DEBUG_SHIRQ_FIXME
1221         if (!retval && (irqflags & IRQF_SHARED)) {
1222                 /*
1223                  * It's a shared IRQ -- the driver ought to be prepared for it
1224                  * to happen immediately, so let's make sure....
1225                  * We disable the irq to make sure that a 'real' IRQ doesn't
1226                  * run in parallel with our fake.
1227                  */
1228                 unsigned long flags;
1229
1230                 disable_irq(irq);
1231                 local_irq_save(flags);
1232
1233                 handler(irq, dev_id);
1234
1235                 local_irq_restore(flags);
1236                 enable_irq(irq);
1237         }
1238 #endif
1239         return retval;
1240 }
1241 EXPORT_SYMBOL(request_threaded_irq);
1242
1243 /**
1244  *      request_any_context_irq - allocate an interrupt line
1245  *      @irq: Interrupt line to allocate
1246  *      @handler: Function to be called when the IRQ occurs.
1247  *                Threaded handler for threaded interrupts.
1248  *      @flags: Interrupt type flags
1249  *      @name: An ascii name for the claiming device
1250  *      @dev_id: A cookie passed back to the handler function
1251  *
1252  *      This call allocates interrupt resources and enables the
1253  *      interrupt line and IRQ handling. It selects either a
1254  *      hardirq or threaded handling method depending on the
1255  *      context.
1256  *
1257  *      On failure, it returns a negative value. On success,
1258  *      it returns either IRQC_IS_HARDIRQ or IRQC_IS_NESTED.
1259  */
1260 int request_any_context_irq(unsigned int irq, irq_handler_t handler,
1261                             unsigned long flags, const char *name, void *dev_id)
1262 {
1263         struct irq_desc *desc = irq_to_desc(irq);
1264         int ret;
1265
1266         if (!desc)
1267                 return -EINVAL;
1268
1269         if (desc->status & IRQ_NESTED_THREAD) {
1270                 ret = request_threaded_irq(irq, NULL, handler,
1271                                            flags, name, dev_id);
1272                 return !ret ? IRQC_IS_NESTED : ret;
1273         }
1274
1275         ret = request_irq(irq, handler, flags, name, dev_id);
1276         return !ret ? IRQC_IS_HARDIRQ : ret;
1277 }
1278 EXPORT_SYMBOL_GPL(request_any_context_irq);