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