irq: Handle spurios irq detection for threaded irqs
[linux-3.10.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 #ifdef CONFIG_IRQ_FORCED_THREADING
21 __read_mostly bool force_irqthreads;
22
23 static int __init setup_forced_irqthreads(char *arg)
24 {
25         force_irqthreads = true;
26         return 0;
27 }
28 early_param("threadirqs", setup_forced_irqthreads);
29 #endif
30
31 /**
32  *      synchronize_irq - wait for pending IRQ handlers (on other CPUs)
33  *      @irq: interrupt number to wait for
34  *
35  *      This function waits for any pending IRQ handlers for this interrupt
36  *      to complete before returning. If you use this function while
37  *      holding a resource the IRQ handler may need you will deadlock.
38  *
39  *      This function may be called - with care - from IRQ context.
40  */
41 void synchronize_irq(unsigned int irq)
42 {
43         struct irq_desc *desc = irq_to_desc(irq);
44         bool inprogress;
45
46         if (!desc)
47                 return;
48
49         do {
50                 unsigned long flags;
51
52                 /*
53                  * Wait until we're out of the critical section.  This might
54                  * give the wrong answer due to the lack of memory barriers.
55                  */
56                 while (irqd_irq_inprogress(&desc->irq_data))
57                         cpu_relax();
58
59                 /* Ok, that indicated we're done: double-check carefully. */
60                 raw_spin_lock_irqsave(&desc->lock, flags);
61                 inprogress = irqd_irq_inprogress(&desc->irq_data);
62                 raw_spin_unlock_irqrestore(&desc->lock, flags);
63
64                 /* Oops, that failed? */
65         } while (inprogress);
66
67         /*
68          * We made sure that no hardirq handler is running. Now verify
69          * that no threaded handlers are active.
70          */
71         wait_event(desc->wait_for_threads, !atomic_read(&desc->threads_active));
72 }
73 EXPORT_SYMBOL(synchronize_irq);
74
75 #ifdef CONFIG_SMP
76 cpumask_var_t irq_default_affinity;
77
78 /**
79  *      irq_can_set_affinity - Check if the affinity of a given irq can be set
80  *      @irq:           Interrupt to check
81  *
82  */
83 int irq_can_set_affinity(unsigned int irq)
84 {
85         struct irq_desc *desc = irq_to_desc(irq);
86
87         if (!desc || !irqd_can_balance(&desc->irq_data) ||
88             !desc->irq_data.chip || !desc->irq_data.chip->irq_set_affinity)
89                 return 0;
90
91         return 1;
92 }
93
94 /**
95  *      irq_set_thread_affinity - Notify irq threads to adjust affinity
96  *      @desc:          irq descriptor which has affitnity changed
97  *
98  *      We just set IRQTF_AFFINITY and delegate the affinity setting
99  *      to the interrupt thread itself. We can not call
100  *      set_cpus_allowed_ptr() here as we hold desc->lock and this
101  *      code can be called from hard interrupt context.
102  */
103 void irq_set_thread_affinity(struct irq_desc *desc)
104 {
105         struct irqaction *action = desc->action;
106
107         while (action) {
108                 if (action->thread)
109                         set_bit(IRQTF_AFFINITY, &action->thread_flags);
110                 action = action->next;
111         }
112 }
113
114 #ifdef CONFIG_GENERIC_PENDING_IRQ
115 static inline bool irq_can_move_pcntxt(struct irq_data *data)
116 {
117         return irqd_can_move_in_process_context(data);
118 }
119 static inline bool irq_move_pending(struct irq_data *data)
120 {
121         return irqd_is_setaffinity_pending(data);
122 }
123 static inline void
124 irq_copy_pending(struct irq_desc *desc, const struct cpumask *mask)
125 {
126         cpumask_copy(desc->pending_mask, mask);
127 }
128 static inline void
129 irq_get_pending(struct cpumask *mask, struct irq_desc *desc)
130 {
131         cpumask_copy(mask, desc->pending_mask);
132 }
133 #else
134 static inline bool irq_can_move_pcntxt(struct irq_data *data) { return true; }
135 static inline bool irq_move_pending(struct irq_data *data) { return false; }
136 static inline void
137 irq_copy_pending(struct irq_desc *desc, const struct cpumask *mask) { }
138 static inline void
139 irq_get_pending(struct cpumask *mask, struct irq_desc *desc) { }
140 #endif
141
142 int __irq_set_affinity_locked(struct irq_data *data, const struct cpumask *mask)
143 {
144         struct irq_chip *chip = irq_data_get_irq_chip(data);
145         struct irq_desc *desc = irq_data_to_desc(data);
146         int ret = 0;
147
148         if (!chip || !chip->irq_set_affinity)
149                 return -EINVAL;
150
151         if (irq_can_move_pcntxt(data)) {
152                 ret = chip->irq_set_affinity(data, mask, false);
153                 switch (ret) {
154                 case IRQ_SET_MASK_OK:
155                         cpumask_copy(data->affinity, mask);
156                 case IRQ_SET_MASK_OK_NOCOPY:
157                         irq_set_thread_affinity(desc);
158                         ret = 0;
159                 }
160         } else {
161                 irqd_set_move_pending(data);
162                 irq_copy_pending(desc, mask);
163         }
164
165         if (desc->affinity_notify) {
166                 kref_get(&desc->affinity_notify->kref);
167                 schedule_work(&desc->affinity_notify->work);
168         }
169         irqd_set(data, IRQD_AFFINITY_SET);
170
171         return ret;
172 }
173
174 /**
175  *      irq_set_affinity - Set the irq affinity of a given irq
176  *      @irq:           Interrupt to set affinity
177  *      @mask:          cpumask
178  *
179  */
180 int irq_set_affinity(unsigned int irq, const struct cpumask *mask)
181 {
182         struct irq_desc *desc = irq_to_desc(irq);
183         unsigned long flags;
184         int ret;
185
186         if (!desc)
187                 return -EINVAL;
188
189         raw_spin_lock_irqsave(&desc->lock, flags);
190         ret =  __irq_set_affinity_locked(irq_desc_get_irq_data(desc), mask);
191         raw_spin_unlock_irqrestore(&desc->lock, flags);
192         return ret;
193 }
194
195 int irq_set_affinity_hint(unsigned int irq, const struct cpumask *m)
196 {
197         unsigned long flags;
198         struct irq_desc *desc = irq_get_desc_lock(irq, &flags);
199
200         if (!desc)
201                 return -EINVAL;
202         desc->affinity_hint = m;
203         irq_put_desc_unlock(desc, flags);
204         return 0;
205 }
206 EXPORT_SYMBOL_GPL(irq_set_affinity_hint);
207
208 static void irq_affinity_notify(struct work_struct *work)
209 {
210         struct irq_affinity_notify *notify =
211                 container_of(work, struct irq_affinity_notify, work);
212         struct irq_desc *desc = irq_to_desc(notify->irq);
213         cpumask_var_t cpumask;
214         unsigned long flags;
215
216         if (!desc || !alloc_cpumask_var(&cpumask, GFP_KERNEL))
217                 goto out;
218
219         raw_spin_lock_irqsave(&desc->lock, flags);
220         if (irq_move_pending(&desc->irq_data))
221                 irq_get_pending(cpumask, desc);
222         else
223                 cpumask_copy(cpumask, desc->irq_data.affinity);
224         raw_spin_unlock_irqrestore(&desc->lock, flags);
225
226         notify->notify(notify, cpumask);
227
228         free_cpumask_var(cpumask);
229 out:
230         kref_put(&notify->kref, notify->release);
231 }
232
233 /**
234  *      irq_set_affinity_notifier - control notification of IRQ affinity changes
235  *      @irq:           Interrupt for which to enable/disable notification
236  *      @notify:        Context for notification, or %NULL to disable
237  *                      notification.  Function pointers must be initialised;
238  *                      the other fields will be initialised by this function.
239  *
240  *      Must be called in process context.  Notification may only be enabled
241  *      after the IRQ is allocated and must be disabled before the IRQ is
242  *      freed using free_irq().
243  */
244 int
245 irq_set_affinity_notifier(unsigned int irq, struct irq_affinity_notify *notify)
246 {
247         struct irq_desc *desc = irq_to_desc(irq);
248         struct irq_affinity_notify *old_notify;
249         unsigned long flags;
250
251         /* The release function is promised process context */
252         might_sleep();
253
254         if (!desc)
255                 return -EINVAL;
256
257         /* Complete initialisation of *notify */
258         if (notify) {
259                 notify->irq = irq;
260                 kref_init(&notify->kref);
261                 INIT_WORK(&notify->work, irq_affinity_notify);
262         }
263
264         raw_spin_lock_irqsave(&desc->lock, flags);
265         old_notify = desc->affinity_notify;
266         desc->affinity_notify = notify;
267         raw_spin_unlock_irqrestore(&desc->lock, flags);
268
269         if (old_notify)
270                 kref_put(&old_notify->kref, old_notify->release);
271
272         return 0;
273 }
274 EXPORT_SYMBOL_GPL(irq_set_affinity_notifier);
275
276 #ifndef CONFIG_AUTO_IRQ_AFFINITY
277 /*
278  * Generic version of the affinity autoselector.
279  */
280 static int
281 setup_affinity(unsigned int irq, struct irq_desc *desc, struct cpumask *mask)
282 {
283         struct irq_chip *chip = irq_desc_get_chip(desc);
284         struct cpumask *set = irq_default_affinity;
285         int ret;
286
287         /* Excludes PER_CPU and NO_BALANCE interrupts */
288         if (!irq_can_set_affinity(irq))
289                 return 0;
290
291         /*
292          * Preserve an userspace affinity setup, but make sure that
293          * one of the targets is online.
294          */
295         if (irqd_has_set(&desc->irq_data, IRQD_AFFINITY_SET)) {
296                 if (cpumask_intersects(desc->irq_data.affinity,
297                                        cpu_online_mask))
298                         set = desc->irq_data.affinity;
299                 else
300                         irqd_clear(&desc->irq_data, IRQD_AFFINITY_SET);
301         }
302
303         cpumask_and(mask, cpu_online_mask, set);
304         ret = chip->irq_set_affinity(&desc->irq_data, mask, false);
305         switch (ret) {
306         case IRQ_SET_MASK_OK:
307                 cpumask_copy(desc->irq_data.affinity, mask);
308         case IRQ_SET_MASK_OK_NOCOPY:
309                 irq_set_thread_affinity(desc);
310         }
311         return 0;
312 }
313 #else
314 static inline int
315 setup_affinity(unsigned int irq, struct irq_desc *d, struct cpumask *mask)
316 {
317         return irq_select_affinity(irq);
318 }
319 #endif
320
321 /*
322  * Called when affinity is set via /proc/irq
323  */
324 int irq_select_affinity_usr(unsigned int irq, struct cpumask *mask)
325 {
326         struct irq_desc *desc = irq_to_desc(irq);
327         unsigned long flags;
328         int ret;
329
330         raw_spin_lock_irqsave(&desc->lock, flags);
331         ret = setup_affinity(irq, desc, mask);
332         raw_spin_unlock_irqrestore(&desc->lock, flags);
333         return ret;
334 }
335
336 #else
337 static inline int
338 setup_affinity(unsigned int irq, struct irq_desc *desc, struct cpumask *mask)
339 {
340         return 0;
341 }
342 #endif
343
344 void __disable_irq(struct irq_desc *desc, unsigned int irq, bool suspend)
345 {
346         if (suspend) {
347                 if (!desc->action || (desc->action->flags & IRQF_NO_SUSPEND))
348                         return;
349                 desc->istate |= IRQS_SUSPENDED;
350         }
351
352         if (!desc->depth++)
353                 irq_disable(desc);
354 }
355
356 static int __disable_irq_nosync(unsigned int irq)
357 {
358         unsigned long flags;
359         struct irq_desc *desc = irq_get_desc_buslock(irq, &flags);
360
361         if (!desc)
362                 return -EINVAL;
363         __disable_irq(desc, irq, false);
364         irq_put_desc_busunlock(desc, flags);
365         return 0;
366 }
367
368 /**
369  *      disable_irq_nosync - disable an irq without waiting
370  *      @irq: Interrupt to disable
371  *
372  *      Disable the selected interrupt line.  Disables and Enables are
373  *      nested.
374  *      Unlike disable_irq(), this function does not ensure existing
375  *      instances of the IRQ handler have completed before returning.
376  *
377  *      This function may be called from IRQ context.
378  */
379 void disable_irq_nosync(unsigned int irq)
380 {
381         __disable_irq_nosync(irq);
382 }
383 EXPORT_SYMBOL(disable_irq_nosync);
384
385 /**
386  *      disable_irq - disable an irq and wait for completion
387  *      @irq: Interrupt to disable
388  *
389  *      Disable the selected interrupt line.  Enables and Disables are
390  *      nested.
391  *      This function waits for any pending IRQ handlers for this interrupt
392  *      to complete before returning. If you use this function while
393  *      holding a resource the IRQ handler may need you will deadlock.
394  *
395  *      This function may be called - with care - from IRQ context.
396  */
397 void disable_irq(unsigned int irq)
398 {
399         if (!__disable_irq_nosync(irq))
400                 synchronize_irq(irq);
401 }
402 EXPORT_SYMBOL(disable_irq);
403
404 void __enable_irq(struct irq_desc *desc, unsigned int irq, bool resume)
405 {
406         if (resume) {
407                 if (!(desc->istate & IRQS_SUSPENDED)) {
408                         if (!desc->action)
409                                 return;
410                         if (!(desc->action->flags & IRQF_FORCE_RESUME))
411                                 return;
412                         /* Pretend that it got disabled ! */
413                         desc->depth++;
414                 }
415                 desc->istate &= ~IRQS_SUSPENDED;
416         }
417
418         switch (desc->depth) {
419         case 0:
420  err_out:
421                 WARN(1, KERN_WARNING "Unbalanced enable for IRQ %d\n", irq);
422                 break;
423         case 1: {
424                 if (desc->istate & IRQS_SUSPENDED)
425                         goto err_out;
426                 /* Prevent probing on this irq: */
427                 irq_settings_set_noprobe(desc);
428                 irq_enable(desc);
429                 check_irq_resend(desc, irq);
430                 /* fall-through */
431         }
432         default:
433                 desc->depth--;
434         }
435 }
436
437 /**
438  *      enable_irq - enable handling of an irq
439  *      @irq: Interrupt to enable
440  *
441  *      Undoes the effect of one call to disable_irq().  If this
442  *      matches the last disable, processing of interrupts on this
443  *      IRQ line is re-enabled.
444  *
445  *      This function may be called from IRQ context only when
446  *      desc->irq_data.chip->bus_lock and desc->chip->bus_sync_unlock are NULL !
447  */
448 void enable_irq(unsigned int irq)
449 {
450         unsigned long flags;
451         struct irq_desc *desc = irq_get_desc_buslock(irq, &flags);
452
453         if (!desc)
454                 return;
455         if (WARN(!desc->irq_data.chip,
456                  KERN_ERR "enable_irq before setup/request_irq: irq %u\n", irq))
457                 goto out;
458
459         __enable_irq(desc, irq, false);
460 out:
461         irq_put_desc_busunlock(desc, flags);
462 }
463 EXPORT_SYMBOL(enable_irq);
464
465 static int set_irq_wake_real(unsigned int irq, unsigned int on)
466 {
467         struct irq_desc *desc = irq_to_desc(irq);
468         int ret = -ENXIO;
469
470         if (desc->irq_data.chip->irq_set_wake)
471                 ret = desc->irq_data.chip->irq_set_wake(&desc->irq_data, on);
472
473         return ret;
474 }
475
476 /**
477  *      irq_set_irq_wake - control irq power management wakeup
478  *      @irq:   interrupt to control
479  *      @on:    enable/disable power management wakeup
480  *
481  *      Enable/disable power management wakeup mode, which is
482  *      disabled by default.  Enables and disables must match,
483  *      just as they match for non-wakeup mode support.
484  *
485  *      Wakeup mode lets this IRQ wake the system from sleep
486  *      states like "suspend to RAM".
487  */
488 int irq_set_irq_wake(unsigned int irq, unsigned int on)
489 {
490         unsigned long flags;
491         struct irq_desc *desc = irq_get_desc_buslock(irq, &flags);
492         int ret = 0;
493
494         /* wakeup-capable irqs can be shared between drivers that
495          * don't need to have the same sleep mode behaviors.
496          */
497         if (on) {
498                 if (desc->wake_depth++ == 0) {
499                         ret = set_irq_wake_real(irq, on);
500                         if (ret)
501                                 desc->wake_depth = 0;
502                         else
503                                 irqd_set(&desc->irq_data, IRQD_WAKEUP_STATE);
504                 }
505         } else {
506                 if (desc->wake_depth == 0) {
507                         WARN(1, "Unbalanced IRQ %d wake disable\n", irq);
508                 } else if (--desc->wake_depth == 0) {
509                         ret = set_irq_wake_real(irq, on);
510                         if (ret)
511                                 desc->wake_depth = 1;
512                         else
513                                 irqd_clear(&desc->irq_data, IRQD_WAKEUP_STATE);
514                 }
515         }
516         irq_put_desc_busunlock(desc, flags);
517         return ret;
518 }
519 EXPORT_SYMBOL(irq_set_irq_wake);
520
521 /*
522  * Internal function that tells the architecture code whether a
523  * particular irq has been exclusively allocated or is available
524  * for driver use.
525  */
526 int can_request_irq(unsigned int irq, unsigned long irqflags)
527 {
528         unsigned long flags;
529         struct irq_desc *desc = irq_get_desc_lock(irq, &flags);
530         int canrequest = 0;
531
532         if (!desc)
533                 return 0;
534
535         if (irq_settings_can_request(desc)) {
536                 if (desc->action)
537                         if (irqflags & desc->action->flags & IRQF_SHARED)
538                                 canrequest =1;
539         }
540         irq_put_desc_unlock(desc, flags);
541         return canrequest;
542 }
543
544 int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
545                       unsigned long flags)
546 {
547         struct irq_chip *chip = desc->irq_data.chip;
548         int ret, unmask = 0;
549
550         if (!chip || !chip->irq_set_type) {
551                 /*
552                  * IRQF_TRIGGER_* but the PIC does not support multiple
553                  * flow-types?
554                  */
555                 pr_debug("No set_type function for IRQ %d (%s)\n", irq,
556                                 chip ? (chip->name ? : "unknown") : "unknown");
557                 return 0;
558         }
559
560         flags &= IRQ_TYPE_SENSE_MASK;
561
562         if (chip->flags & IRQCHIP_SET_TYPE_MASKED) {
563                 if (!irqd_irq_masked(&desc->irq_data))
564                         mask_irq(desc);
565                 if (!irqd_irq_disabled(&desc->irq_data))
566                         unmask = 1;
567         }
568
569         /* caller masked out all except trigger mode flags */
570         ret = chip->irq_set_type(&desc->irq_data, flags);
571
572         switch (ret) {
573         case IRQ_SET_MASK_OK:
574                 irqd_clear(&desc->irq_data, IRQD_TRIGGER_MASK);
575                 irqd_set(&desc->irq_data, flags);
576
577         case IRQ_SET_MASK_OK_NOCOPY:
578                 flags = irqd_get_trigger_type(&desc->irq_data);
579                 irq_settings_set_trigger_mask(desc, flags);
580                 irqd_clear(&desc->irq_data, IRQD_LEVEL);
581                 irq_settings_clr_level(desc);
582                 if (flags & IRQ_TYPE_LEVEL_MASK) {
583                         irq_settings_set_level(desc);
584                         irqd_set(&desc->irq_data, IRQD_LEVEL);
585                 }
586
587                 ret = 0;
588                 break;
589         default:
590                 pr_err("setting trigger mode %lu for irq %u failed (%pF)\n",
591                        flags, irq, chip->irq_set_type);
592         }
593         if (unmask)
594                 unmask_irq(desc);
595         return ret;
596 }
597
598 /*
599  * Default primary interrupt handler for threaded interrupts. Is
600  * assigned as primary handler when request_threaded_irq is called
601  * with handler == NULL. Useful for oneshot interrupts.
602  */
603 static irqreturn_t irq_default_primary_handler(int irq, void *dev_id)
604 {
605         return IRQ_WAKE_THREAD;
606 }
607
608 /*
609  * Primary handler for nested threaded interrupts. Should never be
610  * called.
611  */
612 static irqreturn_t irq_nested_primary_handler(int irq, void *dev_id)
613 {
614         WARN(1, "Primary handler called for nested irq %d\n", irq);
615         return IRQ_NONE;
616 }
617
618 static int irq_wait_for_interrupt(struct irqaction *action)
619 {
620         while (!kthread_should_stop()) {
621                 set_current_state(TASK_INTERRUPTIBLE);
622
623                 if (test_and_clear_bit(IRQTF_RUNTHREAD,
624                                        &action->thread_flags)) {
625                         __set_current_state(TASK_RUNNING);
626                         return 0;
627                 }
628                 schedule();
629         }
630         return -1;
631 }
632
633 /*
634  * Oneshot interrupts keep the irq line masked until the threaded
635  * handler finished. unmask if the interrupt has not been disabled and
636  * is marked MASKED.
637  */
638 static void irq_finalize_oneshot(struct irq_desc *desc,
639                                  struct irqaction *action, bool force)
640 {
641         if (!(desc->istate & IRQS_ONESHOT))
642                 return;
643 again:
644         chip_bus_lock(desc);
645         raw_spin_lock_irq(&desc->lock);
646
647         /*
648          * Implausible though it may be we need to protect us against
649          * the following scenario:
650          *
651          * The thread is faster done than the hard interrupt handler
652          * on the other CPU. If we unmask the irq line then the
653          * interrupt can come in again and masks the line, leaves due
654          * to IRQS_INPROGRESS and the irq line is masked forever.
655          *
656          * This also serializes the state of shared oneshot handlers
657          * versus "desc->threads_onehsot |= action->thread_mask;" in
658          * irq_wake_thread(). See the comment there which explains the
659          * serialization.
660          */
661         if (unlikely(irqd_irq_inprogress(&desc->irq_data))) {
662                 raw_spin_unlock_irq(&desc->lock);
663                 chip_bus_sync_unlock(desc);
664                 cpu_relax();
665                 goto again;
666         }
667
668         /*
669          * Now check again, whether the thread should run. Otherwise
670          * we would clear the threads_oneshot bit of this thread which
671          * was just set.
672          */
673         if (!force && test_bit(IRQTF_RUNTHREAD, &action->thread_flags))
674                 goto out_unlock;
675
676         desc->threads_oneshot &= ~action->thread_mask;
677
678         if (!desc->threads_oneshot && !irqd_irq_disabled(&desc->irq_data) &&
679             irqd_irq_masked(&desc->irq_data))
680                 unmask_irq(desc);
681
682 out_unlock:
683         raw_spin_unlock_irq(&desc->lock);
684         chip_bus_sync_unlock(desc);
685 }
686
687 #ifdef CONFIG_SMP
688 /*
689  * Check whether we need to chasnge the affinity of the interrupt thread.
690  */
691 static void
692 irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action)
693 {
694         cpumask_var_t mask;
695
696         if (!test_and_clear_bit(IRQTF_AFFINITY, &action->thread_flags))
697                 return;
698
699         /*
700          * In case we are out of memory we set IRQTF_AFFINITY again and
701          * try again next time
702          */
703         if (!alloc_cpumask_var(&mask, GFP_KERNEL)) {
704                 set_bit(IRQTF_AFFINITY, &action->thread_flags);
705                 return;
706         }
707
708         raw_spin_lock_irq(&desc->lock);
709         cpumask_copy(mask, desc->irq_data.affinity);
710         raw_spin_unlock_irq(&desc->lock);
711
712         set_cpus_allowed_ptr(current, mask);
713         free_cpumask_var(mask);
714 }
715 #else
716 static inline void
717 irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action) { }
718 #endif
719
720 /*
721  * Interrupts which are not explicitely requested as threaded
722  * interrupts rely on the implicit bh/preempt disable of the hard irq
723  * context. So we need to disable bh here to avoid deadlocks and other
724  * side effects.
725  */
726 static irqreturn_t
727 irq_forced_thread_fn(struct irq_desc *desc, struct irqaction *action)
728 {
729         irqreturn_t ret;
730
731         local_bh_disable();
732         ret = action->thread_fn(action->irq, action->dev_id);
733         irq_finalize_oneshot(desc, action, false);
734         local_bh_enable();
735         return ret;
736 }
737
738 /*
739  * Interrupts explicitely requested as threaded interupts want to be
740  * preemtible - many of them need to sleep and wait for slow busses to
741  * complete.
742  */
743 static irqreturn_t irq_thread_fn(struct irq_desc *desc,
744                 struct irqaction *action)
745 {
746         irqreturn_t ret;
747
748         ret = action->thread_fn(action->irq, action->dev_id);
749         irq_finalize_oneshot(desc, action, false);
750         return ret;
751 }
752
753 /*
754  * Interrupt handler thread
755  */
756 static int irq_thread(void *data)
757 {
758         static const struct sched_param param = {
759                 .sched_priority = MAX_USER_RT_PRIO/2,
760         };
761         struct irqaction *action = data;
762         struct irq_desc *desc = irq_to_desc(action->irq);
763         irqreturn_t (*handler_fn)(struct irq_desc *desc,
764                         struct irqaction *action);
765         int wake;
766
767         if (force_irqthreads & test_bit(IRQTF_FORCED_THREAD,
768                                         &action->thread_flags))
769                 handler_fn = irq_forced_thread_fn;
770         else
771                 handler_fn = irq_thread_fn;
772
773         sched_setscheduler(current, SCHED_FIFO, &param);
774         current->irqaction = action;
775
776         while (!irq_wait_for_interrupt(action)) {
777
778                 irq_thread_check_affinity(desc, action);
779
780                 atomic_inc(&desc->threads_active);
781
782                 raw_spin_lock_irq(&desc->lock);
783                 if (unlikely(irqd_irq_disabled(&desc->irq_data))) {
784                         /*
785                          * CHECKME: We might need a dedicated
786                          * IRQ_THREAD_PENDING flag here, which
787                          * retriggers the thread in check_irq_resend()
788                          * but AFAICT IRQS_PENDING should be fine as it
789                          * retriggers the interrupt itself --- tglx
790                          */
791                         desc->istate |= IRQS_PENDING;
792                         raw_spin_unlock_irq(&desc->lock);
793                 } else {
794                         irqreturn_t action_ret;
795
796                         raw_spin_unlock_irq(&desc->lock);
797                         action_ret = handler_fn(desc, action);
798                         if (!noirqdebug)
799                                 note_interrupt(action->irq, desc, action_ret);
800                 }
801
802                 wake = atomic_dec_and_test(&desc->threads_active);
803
804                 if (wake && waitqueue_active(&desc->wait_for_threads))
805                         wake_up(&desc->wait_for_threads);
806         }
807
808         /* Prevent a stale desc->threads_oneshot */
809         irq_finalize_oneshot(desc, action, true);
810
811         /*
812          * Clear irqaction. Otherwise exit_irq_thread() would make
813          * fuzz about an active irq thread going into nirvana.
814          */
815         current->irqaction = NULL;
816         return 0;
817 }
818
819 /*
820  * Called from do_exit()
821  */
822 void exit_irq_thread(void)
823 {
824         struct task_struct *tsk = current;
825         struct irq_desc *desc;
826
827         if (!tsk->irqaction)
828                 return;
829
830         printk(KERN_ERR
831                "exiting task \"%s\" (%d) is an active IRQ thread (irq %d)\n",
832                tsk->comm ? tsk->comm : "", tsk->pid, tsk->irqaction->irq);
833
834         desc = irq_to_desc(tsk->irqaction->irq);
835
836         /*
837          * Prevent a stale desc->threads_oneshot. Must be called
838          * before setting the IRQTF_DIED flag.
839          */
840         irq_finalize_oneshot(desc, tsk->irqaction, true);
841
842         /*
843          * Set the THREAD DIED flag to prevent further wakeups of the
844          * soon to be gone threaded handler.
845          */
846         set_bit(IRQTF_DIED, &tsk->irqaction->flags);
847 }
848
849 static void irq_setup_forced_threading(struct irqaction *new)
850 {
851         if (!force_irqthreads)
852                 return;
853         if (new->flags & (IRQF_NO_THREAD | IRQF_PERCPU | IRQF_ONESHOT))
854                 return;
855
856         new->flags |= IRQF_ONESHOT;
857
858         if (!new->thread_fn) {
859                 set_bit(IRQTF_FORCED_THREAD, &new->thread_flags);
860                 new->thread_fn = new->handler;
861                 new->handler = irq_default_primary_handler;
862         }
863 }
864
865 /*
866  * Internal function to register an irqaction - typically used to
867  * allocate special interrupts that are part of the architecture.
868  */
869 static int
870 __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
871 {
872         struct irqaction *old, **old_ptr;
873         const char *old_name = NULL;
874         unsigned long flags, thread_mask = 0;
875         int ret, nested, shared = 0;
876         cpumask_var_t mask;
877
878         if (!desc)
879                 return -EINVAL;
880
881         if (desc->irq_data.chip == &no_irq_chip)
882                 return -ENOSYS;
883         /*
884          * Some drivers like serial.c use request_irq() heavily,
885          * so we have to be careful not to interfere with a
886          * running system.
887          */
888         if (new->flags & IRQF_SAMPLE_RANDOM) {
889                 /*
890                  * This function might sleep, we want to call it first,
891                  * outside of the atomic block.
892                  * Yes, this might clear the entropy pool if the wrong
893                  * driver is attempted to be loaded, without actually
894                  * installing a new handler, but is this really a problem,
895                  * only the sysadmin is able to do this.
896                  */
897                 rand_initialize_irq(irq);
898         }
899
900         /*
901          * Check whether the interrupt nests into another interrupt
902          * thread.
903          */
904         nested = irq_settings_is_nested_thread(desc);
905         if (nested) {
906                 if (!new->thread_fn)
907                         return -EINVAL;
908                 /*
909                  * Replace the primary handler which was provided from
910                  * the driver for non nested interrupt handling by the
911                  * dummy function which warns when called.
912                  */
913                 new->handler = irq_nested_primary_handler;
914         } else {
915                 if (irq_settings_can_thread(desc))
916                         irq_setup_forced_threading(new);
917         }
918
919         /*
920          * Create a handler thread when a thread function is supplied
921          * and the interrupt does not nest into another interrupt
922          * thread.
923          */
924         if (new->thread_fn && !nested) {
925                 struct task_struct *t;
926
927                 t = kthread_create(irq_thread, new, "irq/%d-%s", irq,
928                                    new->name);
929                 if (IS_ERR(t))
930                         return PTR_ERR(t);
931                 /*
932                  * We keep the reference to the task struct even if
933                  * the thread dies to avoid that the interrupt code
934                  * references an already freed task_struct.
935                  */
936                 get_task_struct(t);
937                 new->thread = t;
938         }
939
940         if (!alloc_cpumask_var(&mask, GFP_KERNEL)) {
941                 ret = -ENOMEM;
942                 goto out_thread;
943         }
944
945         /*
946          * The following block of code has to be executed atomically
947          */
948         raw_spin_lock_irqsave(&desc->lock, flags);
949         old_ptr = &desc->action;
950         old = *old_ptr;
951         if (old) {
952                 /*
953                  * Can't share interrupts unless both agree to and are
954                  * the same type (level, edge, polarity). So both flag
955                  * fields must have IRQF_SHARED set and the bits which
956                  * set the trigger type must match. Also all must
957                  * agree on ONESHOT.
958                  */
959                 if (!((old->flags & new->flags) & IRQF_SHARED) ||
960                     ((old->flags ^ new->flags) & IRQF_TRIGGER_MASK) ||
961                     ((old->flags ^ new->flags) & IRQF_ONESHOT)) {
962                         old_name = old->name;
963                         goto mismatch;
964                 }
965
966                 /* All handlers must agree on per-cpuness */
967                 if ((old->flags & IRQF_PERCPU) !=
968                     (new->flags & IRQF_PERCPU))
969                         goto mismatch;
970
971                 /* add new interrupt at end of irq queue */
972                 do {
973                         thread_mask |= old->thread_mask;
974                         old_ptr = &old->next;
975                         old = *old_ptr;
976                 } while (old);
977                 shared = 1;
978         }
979
980         /*
981          * Setup the thread mask for this irqaction. Unlikely to have
982          * 32 resp 64 irqs sharing one line, but who knows.
983          */
984         if (new->flags & IRQF_ONESHOT && thread_mask == ~0UL) {
985                 ret = -EBUSY;
986                 goto out_mask;
987         }
988         new->thread_mask = 1 << ffz(thread_mask);
989
990         if (!shared) {
991                 init_waitqueue_head(&desc->wait_for_threads);
992
993                 /* Setup the type (level, edge polarity) if configured: */
994                 if (new->flags & IRQF_TRIGGER_MASK) {
995                         ret = __irq_set_trigger(desc, irq,
996                                         new->flags & IRQF_TRIGGER_MASK);
997
998                         if (ret)
999                                 goto out_mask;
1000                 }
1001
1002                 desc->istate &= ~(IRQS_AUTODETECT | IRQS_SPURIOUS_DISABLED | \
1003                                   IRQS_ONESHOT | IRQS_WAITING);
1004                 irqd_clear(&desc->irq_data, IRQD_IRQ_INPROGRESS);
1005
1006                 if (new->flags & IRQF_PERCPU) {
1007                         irqd_set(&desc->irq_data, IRQD_PER_CPU);
1008                         irq_settings_set_per_cpu(desc);
1009                 }
1010
1011                 if (new->flags & IRQF_ONESHOT)
1012                         desc->istate |= IRQS_ONESHOT;
1013
1014                 if (irq_settings_can_autoenable(desc))
1015                         irq_startup(desc);
1016                 else
1017                         /* Undo nested disables: */
1018                         desc->depth = 1;
1019
1020                 /* Exclude IRQ from balancing if requested */
1021                 if (new->flags & IRQF_NOBALANCING) {
1022                         irq_settings_set_no_balancing(desc);
1023                         irqd_set(&desc->irq_data, IRQD_NO_BALANCING);
1024                 }
1025
1026                 /* Set default affinity mask once everything is setup */
1027                 setup_affinity(irq, desc, mask);
1028
1029         } else if (new->flags & IRQF_TRIGGER_MASK) {
1030                 unsigned int nmsk = new->flags & IRQF_TRIGGER_MASK;
1031                 unsigned int omsk = irq_settings_get_trigger_mask(desc);
1032
1033                 if (nmsk != omsk)
1034                         /* hope the handler works with current  trigger mode */
1035                         pr_warning("IRQ %d uses trigger mode %u; requested %u\n",
1036                                    irq, nmsk, omsk);
1037         }
1038
1039         new->irq = irq;
1040         *old_ptr = new;
1041
1042         /* Reset broken irq detection when installing new handler */
1043         desc->irq_count = 0;
1044         desc->irqs_unhandled = 0;
1045
1046         /*
1047          * Check whether we disabled the irq via the spurious handler
1048          * before. Reenable it and give it another chance.
1049          */
1050         if (shared && (desc->istate & IRQS_SPURIOUS_DISABLED)) {
1051                 desc->istate &= ~IRQS_SPURIOUS_DISABLED;
1052                 __enable_irq(desc, irq, false);
1053         }
1054
1055         raw_spin_unlock_irqrestore(&desc->lock, flags);
1056
1057         /*
1058          * Strictly no need to wake it up, but hung_task complains
1059          * when no hard interrupt wakes the thread up.
1060          */
1061         if (new->thread)
1062                 wake_up_process(new->thread);
1063
1064         register_irq_proc(irq, desc);
1065         new->dir = NULL;
1066         register_handler_proc(irq, new);
1067         free_cpumask_var(mask);
1068
1069         return 0;
1070
1071 mismatch:
1072 #ifdef CONFIG_DEBUG_SHIRQ
1073         if (!(new->flags & IRQF_PROBE_SHARED)) {
1074                 printk(KERN_ERR "IRQ handler type mismatch for IRQ %d\n", irq);
1075                 if (old_name)
1076                         printk(KERN_ERR "current handler: %s\n", old_name);
1077                 dump_stack();
1078         }
1079 #endif
1080         ret = -EBUSY;
1081
1082 out_mask:
1083         raw_spin_unlock_irqrestore(&desc->lock, flags);
1084         free_cpumask_var(mask);
1085
1086 out_thread:
1087         if (new->thread) {
1088                 struct task_struct *t = new->thread;
1089
1090                 new->thread = NULL;
1091                 if (likely(!test_bit(IRQTF_DIED, &new->thread_flags)))
1092                         kthread_stop(t);
1093                 put_task_struct(t);
1094         }
1095         return ret;
1096 }
1097
1098 /**
1099  *      setup_irq - setup an interrupt
1100  *      @irq: Interrupt line to setup
1101  *      @act: irqaction for the interrupt
1102  *
1103  * Used to statically setup interrupts in the early boot process.
1104  */
1105 int setup_irq(unsigned int irq, struct irqaction *act)
1106 {
1107         int retval;
1108         struct irq_desc *desc = irq_to_desc(irq);
1109
1110         chip_bus_lock(desc);
1111         retval = __setup_irq(irq, desc, act);
1112         chip_bus_sync_unlock(desc);
1113
1114         return retval;
1115 }
1116 EXPORT_SYMBOL_GPL(setup_irq);
1117
1118  /*
1119  * Internal function to unregister an irqaction - used to free
1120  * regular and special interrupts that are part of the architecture.
1121  */
1122 static struct irqaction *__free_irq(unsigned int irq, void *dev_id)
1123 {
1124         struct irq_desc *desc = irq_to_desc(irq);
1125         struct irqaction *action, **action_ptr;
1126         unsigned long flags;
1127
1128         WARN(in_interrupt(), "Trying to free IRQ %d from IRQ context!\n", irq);
1129
1130         if (!desc)
1131                 return NULL;
1132
1133         raw_spin_lock_irqsave(&desc->lock, flags);
1134
1135         /*
1136          * There can be multiple actions per IRQ descriptor, find the right
1137          * one based on the dev_id:
1138          */
1139         action_ptr = &desc->action;
1140         for (;;) {
1141                 action = *action_ptr;
1142
1143                 if (!action) {
1144                         WARN(1, "Trying to free already-free IRQ %d\n", irq);
1145                         raw_spin_unlock_irqrestore(&desc->lock, flags);
1146
1147                         return NULL;
1148                 }
1149
1150                 if (action->dev_id == dev_id)
1151                         break;
1152                 action_ptr = &action->next;
1153         }
1154
1155         /* Found it - now remove it from the list of entries: */
1156         *action_ptr = action->next;
1157
1158         /* Currently used only by UML, might disappear one day: */
1159 #ifdef CONFIG_IRQ_RELEASE_METHOD
1160         if (desc->irq_data.chip->release)
1161                 desc->irq_data.chip->release(irq, dev_id);
1162 #endif
1163
1164         /* If this was the last handler, shut down the IRQ line: */
1165         if (!desc->action)
1166                 irq_shutdown(desc);
1167
1168 #ifdef CONFIG_SMP
1169         /* make sure affinity_hint is cleaned up */
1170         if (WARN_ON_ONCE(desc->affinity_hint))
1171                 desc->affinity_hint = NULL;
1172 #endif
1173
1174         raw_spin_unlock_irqrestore(&desc->lock, flags);
1175
1176         unregister_handler_proc(irq, action);
1177
1178         /* Make sure it's not being used on another CPU: */
1179         synchronize_irq(irq);
1180
1181 #ifdef CONFIG_DEBUG_SHIRQ
1182         /*
1183          * It's a shared IRQ -- the driver ought to be prepared for an IRQ
1184          * event to happen even now it's being freed, so let's make sure that
1185          * is so by doing an extra call to the handler ....
1186          *
1187          * ( We do this after actually deregistering it, to make sure that a
1188          *   'real' IRQ doesn't run in * parallel with our fake. )
1189          */
1190         if (action->flags & IRQF_SHARED) {
1191                 local_irq_save(flags);
1192                 action->handler(irq, dev_id);
1193                 local_irq_restore(flags);
1194         }
1195 #endif
1196
1197         if (action->thread) {
1198                 if (!test_bit(IRQTF_DIED, &action->thread_flags))
1199                         kthread_stop(action->thread);
1200                 put_task_struct(action->thread);
1201         }
1202
1203         return action;
1204 }
1205
1206 /**
1207  *      remove_irq - free an interrupt
1208  *      @irq: Interrupt line to free
1209  *      @act: irqaction for the interrupt
1210  *
1211  * Used to remove interrupts statically setup by the early boot process.
1212  */
1213 void remove_irq(unsigned int irq, struct irqaction *act)
1214 {
1215         __free_irq(irq, act->dev_id);
1216 }
1217 EXPORT_SYMBOL_GPL(remove_irq);
1218
1219 /**
1220  *      free_irq - free an interrupt allocated with request_irq
1221  *      @irq: Interrupt line to free
1222  *      @dev_id: Device identity to free
1223  *
1224  *      Remove an interrupt handler. The handler is removed and if the
1225  *      interrupt line is no longer in use by any driver it is disabled.
1226  *      On a shared IRQ the caller must ensure the interrupt is disabled
1227  *      on the card it drives before calling this function. The function
1228  *      does not return until any executing interrupts for this IRQ
1229  *      have completed.
1230  *
1231  *      This function must not be called from interrupt context.
1232  */
1233 void free_irq(unsigned int irq, void *dev_id)
1234 {
1235         struct irq_desc *desc = irq_to_desc(irq);
1236
1237         if (!desc)
1238                 return;
1239
1240 #ifdef CONFIG_SMP
1241         if (WARN_ON(desc->affinity_notify))
1242                 desc->affinity_notify = NULL;
1243 #endif
1244
1245         chip_bus_lock(desc);
1246         kfree(__free_irq(irq, dev_id));
1247         chip_bus_sync_unlock(desc);
1248 }
1249 EXPORT_SYMBOL(free_irq);
1250
1251 /**
1252  *      request_threaded_irq - allocate an interrupt line
1253  *      @irq: Interrupt line to allocate
1254  *      @handler: Function to be called when the IRQ occurs.
1255  *                Primary handler for threaded interrupts
1256  *                If NULL and thread_fn != NULL the default
1257  *                primary handler is installed
1258  *      @thread_fn: Function called from the irq handler thread
1259  *                  If NULL, no irq thread is created
1260  *      @irqflags: Interrupt type flags
1261  *      @devname: An ascii name for the claiming device
1262  *      @dev_id: A cookie passed back to the handler function
1263  *
1264  *      This call allocates interrupt resources and enables the
1265  *      interrupt line and IRQ handling. From the point this
1266  *      call is made your handler function may be invoked. Since
1267  *      your handler function must clear any interrupt the board
1268  *      raises, you must take care both to initialise your hardware
1269  *      and to set up the interrupt handler in the right order.
1270  *
1271  *      If you want to set up a threaded irq handler for your device
1272  *      then you need to supply @handler and @thread_fn. @handler ist
1273  *      still called in hard interrupt context and has to check
1274  *      whether the interrupt originates from the device. If yes it
1275  *      needs to disable the interrupt on the device and return
1276  *      IRQ_WAKE_THREAD which will wake up the handler thread and run
1277  *      @thread_fn. This split handler design is necessary to support
1278  *      shared interrupts.
1279  *
1280  *      Dev_id must be globally unique. Normally the address of the
1281  *      device data structure is used as the cookie. Since the handler
1282  *      receives this value it makes sense to use it.
1283  *
1284  *      If your interrupt is shared you must pass a non NULL dev_id
1285  *      as this is required when freeing the interrupt.
1286  *
1287  *      Flags:
1288  *
1289  *      IRQF_SHARED             Interrupt is shared
1290  *      IRQF_SAMPLE_RANDOM      The interrupt can be used for entropy
1291  *      IRQF_TRIGGER_*          Specify active edge(s) or level
1292  *
1293  */
1294 int request_threaded_irq(unsigned int irq, irq_handler_t handler,
1295                          irq_handler_t thread_fn, unsigned long irqflags,
1296                          const char *devname, void *dev_id)
1297 {
1298         struct irqaction *action;
1299         struct irq_desc *desc;
1300         int retval;
1301
1302         /*
1303          * Sanity-check: shared interrupts must pass in a real dev-ID,
1304          * otherwise we'll have trouble later trying to figure out
1305          * which interrupt is which (messes up the interrupt freeing
1306          * logic etc).
1307          */
1308         if ((irqflags & IRQF_SHARED) && !dev_id)
1309                 return -EINVAL;
1310
1311         desc = irq_to_desc(irq);
1312         if (!desc)
1313                 return -EINVAL;
1314
1315         if (!irq_settings_can_request(desc))
1316                 return -EINVAL;
1317
1318         if (!handler) {
1319                 if (!thread_fn)
1320                         return -EINVAL;
1321                 handler = irq_default_primary_handler;
1322         }
1323
1324         action = kzalloc(sizeof(struct irqaction), GFP_KERNEL);
1325         if (!action)
1326                 return -ENOMEM;
1327
1328         action->handler = handler;
1329         action->thread_fn = thread_fn;
1330         action->flags = irqflags;
1331         action->name = devname;
1332         action->dev_id = dev_id;
1333
1334         chip_bus_lock(desc);
1335         retval = __setup_irq(irq, desc, action);
1336         chip_bus_sync_unlock(desc);
1337
1338         if (retval)
1339                 kfree(action);
1340
1341 #ifdef CONFIG_DEBUG_SHIRQ_FIXME
1342         if (!retval && (irqflags & IRQF_SHARED)) {
1343                 /*
1344                  * It's a shared IRQ -- the driver ought to be prepared for it
1345                  * to happen immediately, so let's make sure....
1346                  * We disable the irq to make sure that a 'real' IRQ doesn't
1347                  * run in parallel with our fake.
1348                  */
1349                 unsigned long flags;
1350
1351                 disable_irq(irq);
1352                 local_irq_save(flags);
1353
1354                 handler(irq, dev_id);
1355
1356                 local_irq_restore(flags);
1357                 enable_irq(irq);
1358         }
1359 #endif
1360         return retval;
1361 }
1362 EXPORT_SYMBOL(request_threaded_irq);
1363
1364 /**
1365  *      request_any_context_irq - allocate an interrupt line
1366  *      @irq: Interrupt line to allocate
1367  *      @handler: Function to be called when the IRQ occurs.
1368  *                Threaded handler for threaded interrupts.
1369  *      @flags: Interrupt type flags
1370  *      @name: An ascii name for the claiming device
1371  *      @dev_id: A cookie passed back to the handler function
1372  *
1373  *      This call allocates interrupt resources and enables the
1374  *      interrupt line and IRQ handling. It selects either a
1375  *      hardirq or threaded handling method depending on the
1376  *      context.
1377  *
1378  *      On failure, it returns a negative value. On success,
1379  *      it returns either IRQC_IS_HARDIRQ or IRQC_IS_NESTED.
1380  */
1381 int request_any_context_irq(unsigned int irq, irq_handler_t handler,
1382                             unsigned long flags, const char *name, void *dev_id)
1383 {
1384         struct irq_desc *desc = irq_to_desc(irq);
1385         int ret;
1386
1387         if (!desc)
1388                 return -EINVAL;
1389
1390         if (irq_settings_is_nested_thread(desc)) {
1391                 ret = request_threaded_irq(irq, NULL, handler,
1392                                            flags, name, dev_id);
1393                 return !ret ? IRQC_IS_NESTED : ret;
1394         }
1395
1396         ret = request_irq(irq, handler, flags, name, dev_id);
1397         return !ret ? IRQC_IS_HARDIRQ : ret;
1398 }
1399 EXPORT_SYMBOL_GPL(request_any_context_irq);