genirq: Namespace cleanup
[linux-2.6.git] / kernel / irq / manage.c
1 /*
2  * linux/kernel/irq/manage.c
3  *
4  * Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
5  * Copyright (C) 2005-2006 Thomas Gleixner
6  *
7  * This file contains driver APIs to the irq subsystem.
8  */
9
10 #include <linux/irq.h>
11 #include <linux/kthread.h>
12 #include <linux/module.h>
13 #include <linux/random.h>
14 #include <linux/interrupt.h>
15 #include <linux/slab.h>
16 #include <linux/sched.h>
17
18 #include "internals.h"
19
20 /**
21  *      synchronize_irq - wait for pending IRQ handlers (on other CPUs)
22  *      @irq: interrupt number to wait for
23  *
24  *      This function waits for any pending IRQ handlers for this interrupt
25  *      to complete before returning. If you use this function while
26  *      holding a resource the IRQ handler may need you will deadlock.
27  *
28  *      This function may be called - with care - from IRQ context.
29  */
30 void synchronize_irq(unsigned int irq)
31 {
32         struct irq_desc *desc = irq_to_desc(irq);
33         unsigned int status;
34
35         if (!desc)
36                 return;
37
38         do {
39                 unsigned long flags;
40
41                 /*
42                  * Wait until we're out of the critical section.  This might
43                  * give the wrong answer due to the lack of memory barriers.
44                  */
45                 while (desc->status & IRQ_INPROGRESS)
46                         cpu_relax();
47
48                 /* Ok, that indicated we're done: double-check carefully. */
49                 raw_spin_lock_irqsave(&desc->lock, flags);
50                 status = desc->status;
51                 raw_spin_unlock_irqrestore(&desc->lock, flags);
52
53                 /* Oops, that failed? */
54         } while (status & IRQ_INPROGRESS);
55
56         /*
57          * We made sure that no hardirq handler is running. Now verify
58          * that no threaded handlers are active.
59          */
60         wait_event(desc->wait_for_threads, !atomic_read(&desc->threads_active));
61 }
62 EXPORT_SYMBOL(synchronize_irq);
63
64 #ifdef CONFIG_SMP
65 cpumask_var_t irq_default_affinity;
66
67 /**
68  *      irq_can_set_affinity - Check if the affinity of a given irq can be set
69  *      @irq:           Interrupt to check
70  *
71  */
72 int irq_can_set_affinity(unsigned int irq)
73 {
74         struct irq_desc *desc = irq_to_desc(irq);
75
76         if (CHECK_IRQ_PER_CPU(desc->status) || !desc->irq_data.chip ||
77             !desc->irq_data.chip->irq_set_affinity)
78                 return 0;
79
80         return 1;
81 }
82
83 /**
84  *      irq_set_thread_affinity - Notify irq threads to adjust affinity
85  *      @desc:          irq descriptor which has affitnity changed
86  *
87  *      We just set IRQTF_AFFINITY and delegate the affinity setting
88  *      to the interrupt thread itself. We can not call
89  *      set_cpus_allowed_ptr() here as we hold desc->lock and this
90  *      code can be called from hard interrupt context.
91  */
92 void irq_set_thread_affinity(struct irq_desc *desc)
93 {
94         struct irqaction *action = desc->action;
95
96         while (action) {
97                 if (action->thread)
98                         set_bit(IRQTF_AFFINITY, &action->thread_flags);
99                 action = action->next;
100         }
101 }
102
103 /**
104  *      irq_set_affinity - Set the irq affinity of a given irq
105  *      @irq:           Interrupt to set affinity
106  *      @cpumask:       cpumask
107  *
108  */
109 int irq_set_affinity(unsigned int irq, const struct cpumask *cpumask)
110 {
111         struct irq_desc *desc = irq_to_desc(irq);
112         struct irq_chip *chip = desc->irq_data.chip;
113         unsigned long flags;
114
115         if (!chip->irq_set_affinity)
116                 return -EINVAL;
117
118         raw_spin_lock_irqsave(&desc->lock, flags);
119
120 #ifdef CONFIG_GENERIC_PENDING_IRQ
121         if (desc->status & IRQ_MOVE_PCNTXT) {
122                 if (!chip->irq_set_affinity(&desc->irq_data, cpumask, false)) {
123                         cpumask_copy(desc->irq_data.affinity, cpumask);
124                         irq_set_thread_affinity(desc);
125                 }
126         }
127         else {
128                 desc->status |= IRQ_MOVE_PENDING;
129                 cpumask_copy(desc->pending_mask, cpumask);
130         }
131 #else
132         if (!chip->irq_set_affinity(&desc->irq_data, cpumask, false)) {
133                 cpumask_copy(desc->irq_data.affinity, cpumask);
134                 irq_set_thread_affinity(desc);
135         }
136 #endif
137         if (desc->affinity_notify) {
138                 kref_get(&desc->affinity_notify->kref);
139                 schedule_work(&desc->affinity_notify->work);
140         }
141         desc->status |= IRQ_AFFINITY_SET;
142         raw_spin_unlock_irqrestore(&desc->lock, flags);
143         return 0;
144 }
145
146 int irq_set_affinity_hint(unsigned int irq, const struct cpumask *m)
147 {
148         struct irq_desc *desc = irq_to_desc(irq);
149         unsigned long flags;
150
151         if (!desc)
152                 return -EINVAL;
153
154         raw_spin_lock_irqsave(&desc->lock, flags);
155         desc->affinity_hint = m;
156         raw_spin_unlock_irqrestore(&desc->lock, flags);
157
158         return 0;
159 }
160 EXPORT_SYMBOL_GPL(irq_set_affinity_hint);
161
162 static void irq_affinity_notify(struct work_struct *work)
163 {
164         struct irq_affinity_notify *notify =
165                 container_of(work, struct irq_affinity_notify, work);
166         struct irq_desc *desc = irq_to_desc(notify->irq);
167         cpumask_var_t cpumask;
168         unsigned long flags;
169
170         if (!desc)
171                 goto out;
172
173         if (!alloc_cpumask_var(&cpumask, GFP_KERNEL))
174                 goto out;
175
176         raw_spin_lock_irqsave(&desc->lock, flags);
177 #ifdef CONFIG_GENERIC_PENDING_IRQ
178         if (desc->status & IRQ_MOVE_PENDING)
179                 cpumask_copy(cpumask, desc->pending_mask);
180         else
181 #endif
182                 cpumask_copy(cpumask, desc->irq_data.affinity);
183         raw_spin_unlock_irqrestore(&desc->lock, flags);
184
185         notify->notify(notify, cpumask);
186
187         free_cpumask_var(cpumask);
188 out:
189         kref_put(&notify->kref, notify->release);
190 }
191
192 /**
193  *      irq_set_affinity_notifier - control notification of IRQ affinity changes
194  *      @irq:           Interrupt for which to enable/disable notification
195  *      @notify:        Context for notification, or %NULL to disable
196  *                      notification.  Function pointers must be initialised;
197  *                      the other fields will be initialised by this function.
198  *
199  *      Must be called in process context.  Notification may only be enabled
200  *      after the IRQ is allocated and must be disabled before the IRQ is
201  *      freed using free_irq().
202  */
203 int
204 irq_set_affinity_notifier(unsigned int irq, struct irq_affinity_notify *notify)
205 {
206         struct irq_desc *desc = irq_to_desc(irq);
207         struct irq_affinity_notify *old_notify;
208         unsigned long flags;
209
210         /* The release function is promised process context */
211         might_sleep();
212
213         if (!desc)
214                 return -EINVAL;
215
216         /* Complete initialisation of *notify */
217         if (notify) {
218                 notify->irq = irq;
219                 kref_init(&notify->kref);
220                 INIT_WORK(&notify->work, irq_affinity_notify);
221         }
222
223         raw_spin_lock_irqsave(&desc->lock, flags);
224         old_notify = desc->affinity_notify;
225         desc->affinity_notify = notify;
226         raw_spin_unlock_irqrestore(&desc->lock, flags);
227
228         if (old_notify)
229                 kref_put(&old_notify->kref, old_notify->release);
230
231         return 0;
232 }
233 EXPORT_SYMBOL_GPL(irq_set_affinity_notifier);
234
235 #ifndef CONFIG_AUTO_IRQ_AFFINITY
236 /*
237  * Generic version of the affinity autoselector.
238  */
239 static int setup_affinity(unsigned int irq, struct irq_desc *desc)
240 {
241         if (!irq_can_set_affinity(irq))
242                 return 0;
243
244         /*
245          * Preserve an userspace affinity setup, but make sure that
246          * one of the targets is online.
247          */
248         if (desc->status & (IRQ_AFFINITY_SET | IRQ_NO_BALANCING)) {
249                 if (cpumask_any_and(desc->irq_data.affinity, cpu_online_mask)
250                     < nr_cpu_ids)
251                         goto set_affinity;
252                 else
253                         desc->status &= ~IRQ_AFFINITY_SET;
254         }
255
256         cpumask_and(desc->irq_data.affinity, cpu_online_mask, irq_default_affinity);
257 set_affinity:
258         desc->irq_data.chip->irq_set_affinity(&desc->irq_data, desc->irq_data.affinity, false);
259
260         return 0;
261 }
262 #else
263 static inline int setup_affinity(unsigned int irq, struct irq_desc *d)
264 {
265         return irq_select_affinity(irq);
266 }
267 #endif
268
269 /*
270  * Called when affinity is set via /proc/irq
271  */
272 int irq_select_affinity_usr(unsigned int irq)
273 {
274         struct irq_desc *desc = irq_to_desc(irq);
275         unsigned long flags;
276         int ret;
277
278         raw_spin_lock_irqsave(&desc->lock, flags);
279         ret = setup_affinity(irq, desc);
280         if (!ret)
281                 irq_set_thread_affinity(desc);
282         raw_spin_unlock_irqrestore(&desc->lock, flags);
283
284         return ret;
285 }
286
287 #else
288 static inline int setup_affinity(unsigned int irq, struct irq_desc *desc)
289 {
290         return 0;
291 }
292 #endif
293
294 void __disable_irq(struct irq_desc *desc, unsigned int irq, bool suspend)
295 {
296         if (suspend) {
297                 if (!desc->action || (desc->action->flags & IRQF_NO_SUSPEND))
298                         return;
299                 desc->status |= IRQ_SUSPENDED;
300         }
301
302         if (!desc->depth++) {
303                 desc->status |= IRQ_DISABLED;
304                 desc->irq_data.chip->irq_disable(&desc->irq_data);
305         }
306 }
307
308 /**
309  *      disable_irq_nosync - disable an irq without waiting
310  *      @irq: Interrupt to disable
311  *
312  *      Disable the selected interrupt line.  Disables and Enables are
313  *      nested.
314  *      Unlike disable_irq(), this function does not ensure existing
315  *      instances of the IRQ handler have completed before returning.
316  *
317  *      This function may be called from IRQ context.
318  */
319 void disable_irq_nosync(unsigned int irq)
320 {
321         struct irq_desc *desc = irq_to_desc(irq);
322         unsigned long flags;
323
324         if (!desc)
325                 return;
326
327         chip_bus_lock(desc);
328         raw_spin_lock_irqsave(&desc->lock, flags);
329         __disable_irq(desc, irq, false);
330         raw_spin_unlock_irqrestore(&desc->lock, flags);
331         chip_bus_sync_unlock(desc);
332 }
333 EXPORT_SYMBOL(disable_irq_nosync);
334
335 /**
336  *      disable_irq - disable an irq and wait for completion
337  *      @irq: Interrupt to disable
338  *
339  *      Disable the selected interrupt line.  Enables and Disables are
340  *      nested.
341  *      This function waits for any pending IRQ handlers for this interrupt
342  *      to complete before returning. If you use this function while
343  *      holding a resource the IRQ handler may need you will deadlock.
344  *
345  *      This function may be called - with care - from IRQ context.
346  */
347 void disable_irq(unsigned int irq)
348 {
349         struct irq_desc *desc = irq_to_desc(irq);
350
351         if (!desc)
352                 return;
353
354         disable_irq_nosync(irq);
355         if (desc->action)
356                 synchronize_irq(irq);
357 }
358 EXPORT_SYMBOL(disable_irq);
359
360 void __enable_irq(struct irq_desc *desc, unsigned int irq, bool resume)
361 {
362         if (resume) {
363                 if (!(desc->status & IRQ_SUSPENDED)) {
364                         if (!desc->action)
365                                 return;
366                         if (!(desc->action->flags & IRQF_FORCE_RESUME))
367                                 return;
368                         /* Pretend that it got disabled ! */
369                         desc->depth++;
370                 }
371                 desc->status &= ~IRQ_SUSPENDED;
372         }
373
374         switch (desc->depth) {
375         case 0:
376  err_out:
377                 WARN(1, KERN_WARNING "Unbalanced enable for IRQ %d\n", irq);
378                 break;
379         case 1: {
380                 unsigned int status = desc->status & ~IRQ_DISABLED;
381
382                 if (desc->status & IRQ_SUSPENDED)
383                         goto err_out;
384                 /* Prevent probing on this irq: */
385                 desc->status = status | IRQ_NOPROBE;
386                 check_irq_resend(desc, irq);
387                 /* fall-through */
388         }
389         default:
390                 desc->depth--;
391         }
392 }
393
394 /**
395  *      enable_irq - enable handling of an irq
396  *      @irq: Interrupt to enable
397  *
398  *      Undoes the effect of one call to disable_irq().  If this
399  *      matches the last disable, processing of interrupts on this
400  *      IRQ line is re-enabled.
401  *
402  *      This function may be called from IRQ context only when
403  *      desc->irq_data.chip->bus_lock and desc->chip->bus_sync_unlock are NULL !
404  */
405 void enable_irq(unsigned int irq)
406 {
407         struct irq_desc *desc = irq_to_desc(irq);
408         unsigned long flags;
409
410         if (!desc)
411                 return;
412
413         if (WARN(!desc->irq_data.chip || !desc->irq_data.chip->irq_enable,
414             KERN_ERR "enable_irq before setup/request_irq: irq %u\n", irq))
415                 return;
416
417         chip_bus_lock(desc);
418         raw_spin_lock_irqsave(&desc->lock, flags);
419         __enable_irq(desc, irq, false);
420         raw_spin_unlock_irqrestore(&desc->lock, flags);
421         chip_bus_sync_unlock(desc);
422 }
423 EXPORT_SYMBOL(enable_irq);
424
425 static int set_irq_wake_real(unsigned int irq, unsigned int on)
426 {
427         struct irq_desc *desc = irq_to_desc(irq);
428         int ret = -ENXIO;
429
430         if (desc->irq_data.chip->irq_set_wake)
431                 ret = desc->irq_data.chip->irq_set_wake(&desc->irq_data, on);
432
433         return ret;
434 }
435
436 /**
437  *      irq_set_irq_wake - control irq power management wakeup
438  *      @irq:   interrupt to control
439  *      @on:    enable/disable power management wakeup
440  *
441  *      Enable/disable power management wakeup mode, which is
442  *      disabled by default.  Enables and disables must match,
443  *      just as they match for non-wakeup mode support.
444  *
445  *      Wakeup mode lets this IRQ wake the system from sleep
446  *      states like "suspend to RAM".
447  */
448 int irq_set_irq_wake(unsigned int irq, unsigned int on)
449 {
450         struct irq_desc *desc = irq_to_desc(irq);
451         unsigned long flags;
452         int ret = 0;
453
454         /* wakeup-capable irqs can be shared between drivers that
455          * don't need to have the same sleep mode behaviors.
456          */
457         chip_bus_lock(desc);
458         raw_spin_lock_irqsave(&desc->lock, flags);
459         if (on) {
460                 if (desc->wake_depth++ == 0) {
461                         ret = set_irq_wake_real(irq, on);
462                         if (ret)
463                                 desc->wake_depth = 0;
464                         else
465                                 desc->status |= IRQ_WAKEUP;
466                 }
467         } else {
468                 if (desc->wake_depth == 0) {
469                         WARN(1, "Unbalanced IRQ %d wake disable\n", irq);
470                 } else if (--desc->wake_depth == 0) {
471                         ret = set_irq_wake_real(irq, on);
472                         if (ret)
473                                 desc->wake_depth = 1;
474                         else
475                                 desc->status &= ~IRQ_WAKEUP;
476                 }
477         }
478
479         raw_spin_unlock_irqrestore(&desc->lock, flags);
480         chip_bus_sync_unlock(desc);
481         return ret;
482 }
483 EXPORT_SYMBOL(irq_set_irq_wake);
484
485 /*
486  * Internal function that tells the architecture code whether a
487  * particular irq has been exclusively allocated or is available
488  * for driver use.
489  */
490 int can_request_irq(unsigned int irq, unsigned long irqflags)
491 {
492         struct irq_desc *desc = irq_to_desc(irq);
493         struct irqaction *action;
494         unsigned long flags;
495
496         if (!desc)
497                 return 0;
498
499         if (desc->status & IRQ_NOREQUEST)
500                 return 0;
501
502         raw_spin_lock_irqsave(&desc->lock, flags);
503         action = desc->action;
504         if (action)
505                 if (irqflags & action->flags & IRQF_SHARED)
506                         action = NULL;
507
508         raw_spin_unlock_irqrestore(&desc->lock, flags);
509
510         return !action;
511 }
512
513 void compat_irq_chip_set_default_handler(struct irq_desc *desc)
514 {
515         /*
516          * If the architecture still has not overriden
517          * the flow handler then zap the default. This
518          * should catch incorrect flow-type setting.
519          */
520         if (desc->handle_irq == &handle_bad_irq)
521                 desc->handle_irq = NULL;
522 }
523
524 int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
525                       unsigned long flags)
526 {
527         int ret;
528         struct irq_chip *chip = desc->irq_data.chip;
529
530         if (!chip || !chip->irq_set_type) {
531                 /*
532                  * IRQF_TRIGGER_* but the PIC does not support multiple
533                  * flow-types?
534                  */
535                 pr_debug("No set_type function for IRQ %d (%s)\n", irq,
536                                 chip ? (chip->name ? : "unknown") : "unknown");
537                 return 0;
538         }
539
540         /* caller masked out all except trigger mode flags */
541         ret = chip->irq_set_type(&desc->irq_data, flags);
542
543         if (ret)
544                 pr_err("setting trigger mode %lu for irq %u failed (%pF)\n",
545                        flags, irq, chip->irq_set_type);
546         else {
547                 if (flags & (IRQ_TYPE_LEVEL_LOW | IRQ_TYPE_LEVEL_HIGH))
548                         flags |= IRQ_LEVEL;
549                 /* note that IRQF_TRIGGER_MASK == IRQ_TYPE_SENSE_MASK */
550                 desc->status &= ~(IRQ_LEVEL | IRQ_TYPE_SENSE_MASK);
551                 desc->status |= flags;
552
553                 if (chip != desc->irq_data.chip)
554                         irq_chip_set_defaults(desc->irq_data.chip);
555         }
556
557         return ret;
558 }
559
560 /*
561  * Default primary interrupt handler for threaded interrupts. Is
562  * assigned as primary handler when request_threaded_irq is called
563  * with handler == NULL. Useful for oneshot interrupts.
564  */
565 static irqreturn_t irq_default_primary_handler(int irq, void *dev_id)
566 {
567         return IRQ_WAKE_THREAD;
568 }
569
570 /*
571  * Primary handler for nested threaded interrupts. Should never be
572  * called.
573  */
574 static irqreturn_t irq_nested_primary_handler(int irq, void *dev_id)
575 {
576         WARN(1, "Primary handler called for nested irq %d\n", irq);
577         return IRQ_NONE;
578 }
579
580 static int irq_wait_for_interrupt(struct irqaction *action)
581 {
582         while (!kthread_should_stop()) {
583                 set_current_state(TASK_INTERRUPTIBLE);
584
585                 if (test_and_clear_bit(IRQTF_RUNTHREAD,
586                                        &action->thread_flags)) {
587                         __set_current_state(TASK_RUNNING);
588                         return 0;
589                 }
590                 schedule();
591         }
592         return -1;
593 }
594
595 /*
596  * Oneshot interrupts keep the irq line masked until the threaded
597  * handler finished. unmask if the interrupt has not been disabled and
598  * is marked MASKED.
599  */
600 static void irq_finalize_oneshot(unsigned int irq, struct irq_desc *desc)
601 {
602 again:
603         chip_bus_lock(desc);
604         raw_spin_lock_irq(&desc->lock);
605
606         /*
607          * Implausible though it may be we need to protect us against
608          * the following scenario:
609          *
610          * The thread is faster done than the hard interrupt handler
611          * on the other CPU. If we unmask the irq line then the
612          * interrupt can come in again and masks the line, leaves due
613          * to IRQ_INPROGRESS and the irq line is masked forever.
614          */
615         if (unlikely(desc->status & IRQ_INPROGRESS)) {
616                 raw_spin_unlock_irq(&desc->lock);
617                 chip_bus_sync_unlock(desc);
618                 cpu_relax();
619                 goto again;
620         }
621
622         if (!(desc->status & IRQ_DISABLED) && (desc->status & IRQ_MASKED)) {
623                 desc->status &= ~IRQ_MASKED;
624                 desc->irq_data.chip->irq_unmask(&desc->irq_data);
625         }
626         raw_spin_unlock_irq(&desc->lock);
627         chip_bus_sync_unlock(desc);
628 }
629
630 #ifdef CONFIG_SMP
631 /*
632  * Check whether we need to change the affinity of the interrupt thread.
633  */
634 static void
635 irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action)
636 {
637         cpumask_var_t mask;
638
639         if (!test_and_clear_bit(IRQTF_AFFINITY, &action->thread_flags))
640                 return;
641
642         /*
643          * In case we are out of memory we set IRQTF_AFFINITY again and
644          * try again next time
645          */
646         if (!alloc_cpumask_var(&mask, GFP_KERNEL)) {
647                 set_bit(IRQTF_AFFINITY, &action->thread_flags);
648                 return;
649         }
650
651         raw_spin_lock_irq(&desc->lock);
652         cpumask_copy(mask, desc->irq_data.affinity);
653         raw_spin_unlock_irq(&desc->lock);
654
655         set_cpus_allowed_ptr(current, mask);
656         free_cpumask_var(mask);
657 }
658 #else
659 static inline void
660 irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action) { }
661 #endif
662
663 /*
664  * Interrupt handler thread
665  */
666 static int irq_thread(void *data)
667 {
668         static const struct sched_param param = {
669                 .sched_priority = MAX_USER_RT_PRIO/2,
670         };
671         struct irqaction *action = data;
672         struct irq_desc *desc = irq_to_desc(action->irq);
673         int wake, oneshot = desc->status & IRQ_ONESHOT;
674
675         sched_setscheduler(current, SCHED_FIFO, &param);
676         current->irqaction = action;
677
678         while (!irq_wait_for_interrupt(action)) {
679
680                 irq_thread_check_affinity(desc, action);
681
682                 atomic_inc(&desc->threads_active);
683
684                 raw_spin_lock_irq(&desc->lock);
685                 if (unlikely(desc->status & IRQ_DISABLED)) {
686                         /*
687                          * CHECKME: We might need a dedicated
688                          * IRQ_THREAD_PENDING flag here, which
689                          * retriggers the thread in check_irq_resend()
690                          * but AFAICT IRQ_PENDING should be fine as it
691                          * retriggers the interrupt itself --- tglx
692                          */
693                         desc->status |= IRQ_PENDING;
694                         raw_spin_unlock_irq(&desc->lock);
695                 } else {
696                         raw_spin_unlock_irq(&desc->lock);
697
698                         action->thread_fn(action->irq, action->dev_id);
699
700                         if (oneshot)
701                                 irq_finalize_oneshot(action->irq, desc);
702                 }
703
704                 wake = atomic_dec_and_test(&desc->threads_active);
705
706                 if (wake && waitqueue_active(&desc->wait_for_threads))
707                         wake_up(&desc->wait_for_threads);
708         }
709
710         /*
711          * Clear irqaction. Otherwise exit_irq_thread() would make
712          * fuzz about an active irq thread going into nirvana.
713          */
714         current->irqaction = NULL;
715         return 0;
716 }
717
718 /*
719  * Called from do_exit()
720  */
721 void exit_irq_thread(void)
722 {
723         struct task_struct *tsk = current;
724
725         if (!tsk->irqaction)
726                 return;
727
728         printk(KERN_ERR
729                "exiting task \"%s\" (%d) is an active IRQ thread (irq %d)\n",
730                tsk->comm ? tsk->comm : "", tsk->pid, tsk->irqaction->irq);
731
732         /*
733          * Set the THREAD DIED flag to prevent further wakeups of the
734          * soon to be gone threaded handler.
735          */
736         set_bit(IRQTF_DIED, &tsk->irqaction->flags);
737 }
738
739 /*
740  * Internal function to register an irqaction - typically used to
741  * allocate special interrupts that are part of the architecture.
742  */
743 static int
744 __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
745 {
746         struct irqaction *old, **old_ptr;
747         const char *old_name = NULL;
748         unsigned long flags;
749         int nested, shared = 0;
750         int ret;
751
752         if (!desc)
753                 return -EINVAL;
754
755         if (desc->irq_data.chip == &no_irq_chip)
756                 return -ENOSYS;
757         /*
758          * Some drivers like serial.c use request_irq() heavily,
759          * so we have to be careful not to interfere with a
760          * running system.
761          */
762         if (new->flags & IRQF_SAMPLE_RANDOM) {
763                 /*
764                  * This function might sleep, we want to call it first,
765                  * outside of the atomic block.
766                  * Yes, this might clear the entropy pool if the wrong
767                  * driver is attempted to be loaded, without actually
768                  * installing a new handler, but is this really a problem,
769                  * only the sysadmin is able to do this.
770                  */
771                 rand_initialize_irq(irq);
772         }
773
774         /* Oneshot interrupts are not allowed with shared */
775         if ((new->flags & IRQF_ONESHOT) && (new->flags & IRQF_SHARED))
776                 return -EINVAL;
777
778         /*
779          * Check whether the interrupt nests into another interrupt
780          * thread.
781          */
782         nested = desc->status & IRQ_NESTED_THREAD;
783         if (nested) {
784                 if (!new->thread_fn)
785                         return -EINVAL;
786                 /*
787                  * Replace the primary handler which was provided from
788                  * the driver for non nested interrupt handling by the
789                  * dummy function which warns when called.
790                  */
791                 new->handler = irq_nested_primary_handler;
792         }
793
794         /*
795          * Create a handler thread when a thread function is supplied
796          * and the interrupt does not nest into another interrupt
797          * thread.
798          */
799         if (new->thread_fn && !nested) {
800                 struct task_struct *t;
801
802                 t = kthread_create(irq_thread, new, "irq/%d-%s", irq,
803                                    new->name);
804                 if (IS_ERR(t))
805                         return PTR_ERR(t);
806                 /*
807                  * We keep the reference to the task struct even if
808                  * the thread dies to avoid that the interrupt code
809                  * references an already freed task_struct.
810                  */
811                 get_task_struct(t);
812                 new->thread = t;
813         }
814
815         /*
816          * The following block of code has to be executed atomically
817          */
818         raw_spin_lock_irqsave(&desc->lock, flags);
819         old_ptr = &desc->action;
820         old = *old_ptr;
821         if (old) {
822                 /*
823                  * Can't share interrupts unless both agree to and are
824                  * the same type (level, edge, polarity). So both flag
825                  * fields must have IRQF_SHARED set and the bits which
826                  * set the trigger type must match.
827                  */
828                 if (!((old->flags & new->flags) & IRQF_SHARED) ||
829                     ((old->flags ^ new->flags) & IRQF_TRIGGER_MASK)) {
830                         old_name = old->name;
831                         goto mismatch;
832                 }
833
834 #if defined(CONFIG_IRQ_PER_CPU)
835                 /* All handlers must agree on per-cpuness */
836                 if ((old->flags & IRQF_PERCPU) !=
837                     (new->flags & IRQF_PERCPU))
838                         goto mismatch;
839 #endif
840
841                 /* add new interrupt at end of irq queue */
842                 do {
843                         old_ptr = &old->next;
844                         old = *old_ptr;
845                 } while (old);
846                 shared = 1;
847         }
848
849         if (!shared) {
850                 irq_chip_set_defaults(desc->irq_data.chip);
851
852                 init_waitqueue_head(&desc->wait_for_threads);
853
854                 /* Setup the type (level, edge polarity) if configured: */
855                 if (new->flags & IRQF_TRIGGER_MASK) {
856                         ret = __irq_set_trigger(desc, irq,
857                                         new->flags & IRQF_TRIGGER_MASK);
858
859                         if (ret)
860                                 goto out_thread;
861                 } else
862                         compat_irq_chip_set_default_handler(desc);
863 #if defined(CONFIG_IRQ_PER_CPU)
864                 if (new->flags & IRQF_PERCPU)
865                         desc->status |= IRQ_PER_CPU;
866 #endif
867
868                 desc->status &= ~(IRQ_AUTODETECT | IRQ_WAITING | IRQ_ONESHOT |
869                                   IRQ_INPROGRESS | IRQ_SPURIOUS_DISABLED);
870
871                 if (new->flags & IRQF_ONESHOT)
872                         desc->status |= IRQ_ONESHOT;
873
874                 if (!(desc->status & IRQ_NOAUTOEN)) {
875                         desc->depth = 0;
876                         desc->status &= ~IRQ_DISABLED;
877                         desc->irq_data.chip->irq_startup(&desc->irq_data);
878                 } else
879                         /* Undo nested disables: */
880                         desc->depth = 1;
881
882                 /* Exclude IRQ from balancing if requested */
883                 if (new->flags & IRQF_NOBALANCING)
884                         desc->status |= IRQ_NO_BALANCING;
885
886                 /* Set default affinity mask once everything is setup */
887                 setup_affinity(irq, desc);
888
889         } else if ((new->flags & IRQF_TRIGGER_MASK)
890                         && (new->flags & IRQF_TRIGGER_MASK)
891                                 != (desc->status & IRQ_TYPE_SENSE_MASK)) {
892                 /* hope the handler works with the actual trigger mode... */
893                 pr_warning("IRQ %d uses trigger mode %d; requested %d\n",
894                                 irq, (int)(desc->status & IRQ_TYPE_SENSE_MASK),
895                                 (int)(new->flags & IRQF_TRIGGER_MASK));
896         }
897
898         new->irq = irq;
899         *old_ptr = new;
900
901         /* Reset broken irq detection when installing new handler */
902         desc->irq_count = 0;
903         desc->irqs_unhandled = 0;
904
905         /*
906          * Check whether we disabled the irq via the spurious handler
907          * before. Reenable it and give it another chance.
908          */
909         if (shared && (desc->status & IRQ_SPURIOUS_DISABLED)) {
910                 desc->status &= ~IRQ_SPURIOUS_DISABLED;
911                 __enable_irq(desc, irq, false);
912         }
913
914         raw_spin_unlock_irqrestore(&desc->lock, flags);
915
916         /*
917          * Strictly no need to wake it up, but hung_task complains
918          * when no hard interrupt wakes the thread up.
919          */
920         if (new->thread)
921                 wake_up_process(new->thread);
922
923         register_irq_proc(irq, desc);
924         new->dir = NULL;
925         register_handler_proc(irq, new);
926
927         return 0;
928
929 mismatch:
930 #ifdef CONFIG_DEBUG_SHIRQ
931         if (!(new->flags & IRQF_PROBE_SHARED)) {
932                 printk(KERN_ERR "IRQ handler type mismatch for IRQ %d\n", irq);
933                 if (old_name)
934                         printk(KERN_ERR "current handler: %s\n", old_name);
935                 dump_stack();
936         }
937 #endif
938         ret = -EBUSY;
939
940 out_thread:
941         raw_spin_unlock_irqrestore(&desc->lock, flags);
942         if (new->thread) {
943                 struct task_struct *t = new->thread;
944
945                 new->thread = NULL;
946                 if (likely(!test_bit(IRQTF_DIED, &new->thread_flags)))
947                         kthread_stop(t);
948                 put_task_struct(t);
949         }
950         return ret;
951 }
952
953 /**
954  *      setup_irq - setup an interrupt
955  *      @irq: Interrupt line to setup
956  *      @act: irqaction for the interrupt
957  *
958  * Used to statically setup interrupts in the early boot process.
959  */
960 int setup_irq(unsigned int irq, struct irqaction *act)
961 {
962         int retval;
963         struct irq_desc *desc = irq_to_desc(irq);
964
965         chip_bus_lock(desc);
966         retval = __setup_irq(irq, desc, act);
967         chip_bus_sync_unlock(desc);
968
969         return retval;
970 }
971 EXPORT_SYMBOL_GPL(setup_irq);
972
973  /*
974  * Internal function to unregister an irqaction - used to free
975  * regular and special interrupts that are part of the architecture.
976  */
977 static struct irqaction *__free_irq(unsigned int irq, void *dev_id)
978 {
979         struct irq_desc *desc = irq_to_desc(irq);
980         struct irqaction *action, **action_ptr;
981         unsigned long flags;
982
983         WARN(in_interrupt(), "Trying to free IRQ %d from IRQ context!\n", irq);
984
985         if (!desc)
986                 return NULL;
987
988         raw_spin_lock_irqsave(&desc->lock, flags);
989
990         /*
991          * There can be multiple actions per IRQ descriptor, find the right
992          * one based on the dev_id:
993          */
994         action_ptr = &desc->action;
995         for (;;) {
996                 action = *action_ptr;
997
998                 if (!action) {
999                         WARN(1, "Trying to free already-free IRQ %d\n", irq);
1000                         raw_spin_unlock_irqrestore(&desc->lock, flags);
1001
1002                         return NULL;
1003                 }
1004
1005                 if (action->dev_id == dev_id)
1006                         break;
1007                 action_ptr = &action->next;
1008         }
1009
1010         /* Found it - now remove it from the list of entries: */
1011         *action_ptr = action->next;
1012
1013         /* Currently used only by UML, might disappear one day: */
1014 #ifdef CONFIG_IRQ_RELEASE_METHOD
1015         if (desc->irq_data.chip->release)
1016                 desc->irq_data.chip->release(irq, dev_id);
1017 #endif
1018
1019         /* If this was the last handler, shut down the IRQ line: */
1020         if (!desc->action) {
1021                 desc->status |= IRQ_DISABLED;
1022                 if (desc->irq_data.chip->irq_shutdown)
1023                         desc->irq_data.chip->irq_shutdown(&desc->irq_data);
1024                 else
1025                         desc->irq_data.chip->irq_disable(&desc->irq_data);
1026         }
1027
1028 #ifdef CONFIG_SMP
1029         /* make sure affinity_hint is cleaned up */
1030         if (WARN_ON_ONCE(desc->affinity_hint))
1031                 desc->affinity_hint = NULL;
1032 #endif
1033
1034         raw_spin_unlock_irqrestore(&desc->lock, flags);
1035
1036         unregister_handler_proc(irq, action);
1037
1038         /* Make sure it's not being used on another CPU: */
1039         synchronize_irq(irq);
1040
1041 #ifdef CONFIG_DEBUG_SHIRQ
1042         /*
1043          * It's a shared IRQ -- the driver ought to be prepared for an IRQ
1044          * event to happen even now it's being freed, so let's make sure that
1045          * is so by doing an extra call to the handler ....
1046          *
1047          * ( We do this after actually deregistering it, to make sure that a
1048          *   'real' IRQ doesn't run in * parallel with our fake. )
1049          */
1050         if (action->flags & IRQF_SHARED) {
1051                 local_irq_save(flags);
1052                 action->handler(irq, dev_id);
1053                 local_irq_restore(flags);
1054         }
1055 #endif
1056
1057         if (action->thread) {
1058                 if (!test_bit(IRQTF_DIED, &action->thread_flags))
1059                         kthread_stop(action->thread);
1060                 put_task_struct(action->thread);
1061         }
1062
1063         return action;
1064 }
1065
1066 /**
1067  *      remove_irq - free an interrupt
1068  *      @irq: Interrupt line to free
1069  *      @act: irqaction for the interrupt
1070  *
1071  * Used to remove interrupts statically setup by the early boot process.
1072  */
1073 void remove_irq(unsigned int irq, struct irqaction *act)
1074 {
1075         __free_irq(irq, act->dev_id);
1076 }
1077 EXPORT_SYMBOL_GPL(remove_irq);
1078
1079 /**
1080  *      free_irq - free an interrupt allocated with request_irq
1081  *      @irq: Interrupt line to free
1082  *      @dev_id: Device identity to free
1083  *
1084  *      Remove an interrupt handler. The handler is removed and if the
1085  *      interrupt line is no longer in use by any driver it is disabled.
1086  *      On a shared IRQ the caller must ensure the interrupt is disabled
1087  *      on the card it drives before calling this function. The function
1088  *      does not return until any executing interrupts for this IRQ
1089  *      have completed.
1090  *
1091  *      This function must not be called from interrupt context.
1092  */
1093 void free_irq(unsigned int irq, void *dev_id)
1094 {
1095         struct irq_desc *desc = irq_to_desc(irq);
1096
1097         if (!desc)
1098                 return;
1099
1100 #ifdef CONFIG_SMP
1101         if (WARN_ON(desc->affinity_notify))
1102                 desc->affinity_notify = NULL;
1103 #endif
1104
1105         chip_bus_lock(desc);
1106         kfree(__free_irq(irq, dev_id));
1107         chip_bus_sync_unlock(desc);
1108 }
1109 EXPORT_SYMBOL(free_irq);
1110
1111 /**
1112  *      request_threaded_irq - allocate an interrupt line
1113  *      @irq: Interrupt line to allocate
1114  *      @handler: Function to be called when the IRQ occurs.
1115  *                Primary handler for threaded interrupts
1116  *                If NULL and thread_fn != NULL the default
1117  *                primary handler is installed
1118  *      @thread_fn: Function called from the irq handler thread
1119  *                  If NULL, no irq thread is created
1120  *      @irqflags: Interrupt type flags
1121  *      @devname: An ascii name for the claiming device
1122  *      @dev_id: A cookie passed back to the handler function
1123  *
1124  *      This call allocates interrupt resources and enables the
1125  *      interrupt line and IRQ handling. From the point this
1126  *      call is made your handler function may be invoked. Since
1127  *      your handler function must clear any interrupt the board
1128  *      raises, you must take care both to initialise your hardware
1129  *      and to set up the interrupt handler in the right order.
1130  *
1131  *      If you want to set up a threaded irq handler for your device
1132  *      then you need to supply @handler and @thread_fn. @handler ist
1133  *      still called in hard interrupt context and has to check
1134  *      whether the interrupt originates from the device. If yes it
1135  *      needs to disable the interrupt on the device and return
1136  *      IRQ_WAKE_THREAD which will wake up the handler thread and run
1137  *      @thread_fn. This split handler design is necessary to support
1138  *      shared interrupts.
1139  *
1140  *      Dev_id must be globally unique. Normally the address of the
1141  *      device data structure is used as the cookie. Since the handler
1142  *      receives this value it makes sense to use it.
1143  *
1144  *      If your interrupt is shared you must pass a non NULL dev_id
1145  *      as this is required when freeing the interrupt.
1146  *
1147  *      Flags:
1148  *
1149  *      IRQF_SHARED             Interrupt is shared
1150  *      IRQF_SAMPLE_RANDOM      The interrupt can be used for entropy
1151  *      IRQF_TRIGGER_*          Specify active edge(s) or level
1152  *
1153  */
1154 int request_threaded_irq(unsigned int irq, irq_handler_t handler,
1155                          irq_handler_t thread_fn, unsigned long irqflags,
1156                          const char *devname, void *dev_id)
1157 {
1158         struct irqaction *action;
1159         struct irq_desc *desc;
1160         int retval;
1161
1162         /*
1163          * Sanity-check: shared interrupts must pass in a real dev-ID,
1164          * otherwise we'll have trouble later trying to figure out
1165          * which interrupt is which (messes up the interrupt freeing
1166          * logic etc).
1167          */
1168         if ((irqflags & IRQF_SHARED) && !dev_id)
1169                 return -EINVAL;
1170
1171         desc = irq_to_desc(irq);
1172         if (!desc)
1173                 return -EINVAL;
1174
1175         if (desc->status & IRQ_NOREQUEST)
1176                 return -EINVAL;
1177
1178         if (!handler) {
1179                 if (!thread_fn)
1180                         return -EINVAL;
1181                 handler = irq_default_primary_handler;
1182         }
1183
1184         action = kzalloc(sizeof(struct irqaction), GFP_KERNEL);
1185         if (!action)
1186                 return -ENOMEM;
1187
1188         action->handler = handler;
1189         action->thread_fn = thread_fn;
1190         action->flags = irqflags;
1191         action->name = devname;
1192         action->dev_id = dev_id;
1193
1194         chip_bus_lock(desc);
1195         retval = __setup_irq(irq, desc, action);
1196         chip_bus_sync_unlock(desc);
1197
1198         if (retval)
1199                 kfree(action);
1200
1201 #ifdef CONFIG_DEBUG_SHIRQ_FIXME
1202         if (!retval && (irqflags & IRQF_SHARED)) {
1203                 /*
1204                  * It's a shared IRQ -- the driver ought to be prepared for it
1205                  * to happen immediately, so let's make sure....
1206                  * We disable the irq to make sure that a 'real' IRQ doesn't
1207                  * run in parallel with our fake.
1208                  */
1209                 unsigned long flags;
1210
1211                 disable_irq(irq);
1212                 local_irq_save(flags);
1213
1214                 handler(irq, dev_id);
1215
1216                 local_irq_restore(flags);
1217                 enable_irq(irq);
1218         }
1219 #endif
1220         return retval;
1221 }
1222 EXPORT_SYMBOL(request_threaded_irq);
1223
1224 /**
1225  *      request_any_context_irq - allocate an interrupt line
1226  *      @irq: Interrupt line to allocate
1227  *      @handler: Function to be called when the IRQ occurs.
1228  *                Threaded handler for threaded interrupts.
1229  *      @flags: Interrupt type flags
1230  *      @name: An ascii name for the claiming device
1231  *      @dev_id: A cookie passed back to the handler function
1232  *
1233  *      This call allocates interrupt resources and enables the
1234  *      interrupt line and IRQ handling. It selects either a
1235  *      hardirq or threaded handling method depending on the
1236  *      context.
1237  *
1238  *      On failure, it returns a negative value. On success,
1239  *      it returns either IRQC_IS_HARDIRQ or IRQC_IS_NESTED.
1240  */
1241 int request_any_context_irq(unsigned int irq, irq_handler_t handler,
1242                             unsigned long flags, const char *name, void *dev_id)
1243 {
1244         struct irq_desc *desc = irq_to_desc(irq);
1245         int ret;
1246
1247         if (!desc)
1248                 return -EINVAL;
1249
1250         if (desc->status & IRQ_NESTED_THREAD) {
1251                 ret = request_threaded_irq(irq, NULL, handler,
1252                                            flags, name, dev_id);
1253                 return !ret ? IRQC_IS_NESTED : ret;
1254         }
1255
1256         ret = request_irq(irq, handler, flags, name, dev_id);
1257         return !ret ? IRQC_IS_HARDIRQ : ret;
1258 }
1259 EXPORT_SYMBOL_GPL(request_any_context_irq);