xref: /openbmc/linux/kernel/irq/manage.c (revision 6774def6)
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 #define pr_fmt(fmt) "genirq: " fmt
11 
12 #include <linux/irq.h>
13 #include <linux/kthread.h>
14 #include <linux/module.h>
15 #include <linux/random.h>
16 #include <linux/interrupt.h>
17 #include <linux/slab.h>
18 #include <linux/sched.h>
19 #include <linux/sched/rt.h>
20 #include <linux/task_work.h>
21 
22 #include "internals.h"
23 
24 #ifdef CONFIG_IRQ_FORCED_THREADING
25 __read_mostly bool force_irqthreads;
26 
27 static int __init setup_forced_irqthreads(char *arg)
28 {
29 	force_irqthreads = true;
30 	return 0;
31 }
32 early_param("threadirqs", setup_forced_irqthreads);
33 #endif
34 
35 static void __synchronize_hardirq(struct irq_desc *desc)
36 {
37 	bool inprogress;
38 
39 	do {
40 		unsigned long flags;
41 
42 		/*
43 		 * Wait until we're out of the critical section.  This might
44 		 * give the wrong answer due to the lack of memory barriers.
45 		 */
46 		while (irqd_irq_inprogress(&desc->irq_data))
47 			cpu_relax();
48 
49 		/* Ok, that indicated we're done: double-check carefully. */
50 		raw_spin_lock_irqsave(&desc->lock, flags);
51 		inprogress = irqd_irq_inprogress(&desc->irq_data);
52 		raw_spin_unlock_irqrestore(&desc->lock, flags);
53 
54 		/* Oops, that failed? */
55 	} while (inprogress);
56 }
57 
58 /**
59  *	synchronize_hardirq - wait for pending hard IRQ handlers (on other CPUs)
60  *	@irq: interrupt number to wait for
61  *
62  *	This function waits for any pending hard IRQ handlers for this
63  *	interrupt to complete before returning. If you use this
64  *	function while holding a resource the IRQ handler may need you
65  *	will deadlock. It does not take associated threaded handlers
66  *	into account.
67  *
68  *	Do not use this for shutdown scenarios where you must be sure
69  *	that all parts (hardirq and threaded handler) have completed.
70  *
71  *	This function may be called - with care - from IRQ context.
72  */
73 void synchronize_hardirq(unsigned int irq)
74 {
75 	struct irq_desc *desc = irq_to_desc(irq);
76 
77 	if (desc)
78 		__synchronize_hardirq(desc);
79 }
80 EXPORT_SYMBOL(synchronize_hardirq);
81 
82 /**
83  *	synchronize_irq - wait for pending IRQ handlers (on other CPUs)
84  *	@irq: interrupt number to wait for
85  *
86  *	This function waits for any pending IRQ handlers for this interrupt
87  *	to complete before returning. If you use this function while
88  *	holding a resource the IRQ handler may need you will deadlock.
89  *
90  *	This function may be called - with care - from IRQ context.
91  */
92 void synchronize_irq(unsigned int irq)
93 {
94 	struct irq_desc *desc = irq_to_desc(irq);
95 
96 	if (desc) {
97 		__synchronize_hardirq(desc);
98 		/*
99 		 * We made sure that no hardirq handler is
100 		 * running. Now verify that no threaded handlers are
101 		 * active.
102 		 */
103 		wait_event(desc->wait_for_threads,
104 			   !atomic_read(&desc->threads_active));
105 	}
106 }
107 EXPORT_SYMBOL(synchronize_irq);
108 
109 #ifdef CONFIG_SMP
110 cpumask_var_t irq_default_affinity;
111 
112 /**
113  *	irq_can_set_affinity - Check if the affinity of a given irq can be set
114  *	@irq:		Interrupt to check
115  *
116  */
117 int irq_can_set_affinity(unsigned int irq)
118 {
119 	struct irq_desc *desc = irq_to_desc(irq);
120 
121 	if (!desc || !irqd_can_balance(&desc->irq_data) ||
122 	    !desc->irq_data.chip || !desc->irq_data.chip->irq_set_affinity)
123 		return 0;
124 
125 	return 1;
126 }
127 
128 /**
129  *	irq_set_thread_affinity - Notify irq threads to adjust affinity
130  *	@desc:		irq descriptor which has affitnity changed
131  *
132  *	We just set IRQTF_AFFINITY and delegate the affinity setting
133  *	to the interrupt thread itself. We can not call
134  *	set_cpus_allowed_ptr() here as we hold desc->lock and this
135  *	code can be called from hard interrupt context.
136  */
137 void irq_set_thread_affinity(struct irq_desc *desc)
138 {
139 	struct irqaction *action = desc->action;
140 
141 	while (action) {
142 		if (action->thread)
143 			set_bit(IRQTF_AFFINITY, &action->thread_flags);
144 		action = action->next;
145 	}
146 }
147 
148 #ifdef CONFIG_GENERIC_PENDING_IRQ
149 static inline bool irq_can_move_pcntxt(struct irq_data *data)
150 {
151 	return irqd_can_move_in_process_context(data);
152 }
153 static inline bool irq_move_pending(struct irq_data *data)
154 {
155 	return irqd_is_setaffinity_pending(data);
156 }
157 static inline void
158 irq_copy_pending(struct irq_desc *desc, const struct cpumask *mask)
159 {
160 	cpumask_copy(desc->pending_mask, mask);
161 }
162 static inline void
163 irq_get_pending(struct cpumask *mask, struct irq_desc *desc)
164 {
165 	cpumask_copy(mask, desc->pending_mask);
166 }
167 #else
168 static inline bool irq_can_move_pcntxt(struct irq_data *data) { return true; }
169 static inline bool irq_move_pending(struct irq_data *data) { return false; }
170 static inline void
171 irq_copy_pending(struct irq_desc *desc, const struct cpumask *mask) { }
172 static inline void
173 irq_get_pending(struct cpumask *mask, struct irq_desc *desc) { }
174 #endif
175 
176 int irq_do_set_affinity(struct irq_data *data, const struct cpumask *mask,
177 			bool force)
178 {
179 	struct irq_desc *desc = irq_data_to_desc(data);
180 	struct irq_chip *chip = irq_data_get_irq_chip(data);
181 	int ret;
182 
183 	ret = chip->irq_set_affinity(data, mask, force);
184 	switch (ret) {
185 	case IRQ_SET_MASK_OK:
186 		cpumask_copy(data->affinity, mask);
187 	case IRQ_SET_MASK_OK_NOCOPY:
188 		irq_set_thread_affinity(desc);
189 		ret = 0;
190 	}
191 
192 	return ret;
193 }
194 
195 int irq_set_affinity_locked(struct irq_data *data, const struct cpumask *mask,
196 			    bool force)
197 {
198 	struct irq_chip *chip = irq_data_get_irq_chip(data);
199 	struct irq_desc *desc = irq_data_to_desc(data);
200 	int ret = 0;
201 
202 	if (!chip || !chip->irq_set_affinity)
203 		return -EINVAL;
204 
205 	if (irq_can_move_pcntxt(data)) {
206 		ret = irq_do_set_affinity(data, mask, force);
207 	} else {
208 		irqd_set_move_pending(data);
209 		irq_copy_pending(desc, mask);
210 	}
211 
212 	if (desc->affinity_notify) {
213 		kref_get(&desc->affinity_notify->kref);
214 		schedule_work(&desc->affinity_notify->work);
215 	}
216 	irqd_set(data, IRQD_AFFINITY_SET);
217 
218 	return ret;
219 }
220 
221 int __irq_set_affinity(unsigned int irq, const struct cpumask *mask, bool force)
222 {
223 	struct irq_desc *desc = irq_to_desc(irq);
224 	unsigned long flags;
225 	int ret;
226 
227 	if (!desc)
228 		return -EINVAL;
229 
230 	raw_spin_lock_irqsave(&desc->lock, flags);
231 	ret = irq_set_affinity_locked(irq_desc_get_irq_data(desc), mask, force);
232 	raw_spin_unlock_irqrestore(&desc->lock, flags);
233 	return ret;
234 }
235 
236 int irq_set_affinity_hint(unsigned int irq, const struct cpumask *m)
237 {
238 	unsigned long flags;
239 	struct irq_desc *desc = irq_get_desc_lock(irq, &flags, IRQ_GET_DESC_CHECK_GLOBAL);
240 
241 	if (!desc)
242 		return -EINVAL;
243 	desc->affinity_hint = m;
244 	irq_put_desc_unlock(desc, flags);
245 	return 0;
246 }
247 EXPORT_SYMBOL_GPL(irq_set_affinity_hint);
248 
249 static void irq_affinity_notify(struct work_struct *work)
250 {
251 	struct irq_affinity_notify *notify =
252 		container_of(work, struct irq_affinity_notify, work);
253 	struct irq_desc *desc = irq_to_desc(notify->irq);
254 	cpumask_var_t cpumask;
255 	unsigned long flags;
256 
257 	if (!desc || !alloc_cpumask_var(&cpumask, GFP_KERNEL))
258 		goto out;
259 
260 	raw_spin_lock_irqsave(&desc->lock, flags);
261 	if (irq_move_pending(&desc->irq_data))
262 		irq_get_pending(cpumask, desc);
263 	else
264 		cpumask_copy(cpumask, desc->irq_data.affinity);
265 	raw_spin_unlock_irqrestore(&desc->lock, flags);
266 
267 	notify->notify(notify, cpumask);
268 
269 	free_cpumask_var(cpumask);
270 out:
271 	kref_put(&notify->kref, notify->release);
272 }
273 
274 /**
275  *	irq_set_affinity_notifier - control notification of IRQ affinity changes
276  *	@irq:		Interrupt for which to enable/disable notification
277  *	@notify:	Context for notification, or %NULL to disable
278  *			notification.  Function pointers must be initialised;
279  *			the other fields will be initialised by this function.
280  *
281  *	Must be called in process context.  Notification may only be enabled
282  *	after the IRQ is allocated and must be disabled before the IRQ is
283  *	freed using free_irq().
284  */
285 int
286 irq_set_affinity_notifier(unsigned int irq, struct irq_affinity_notify *notify)
287 {
288 	struct irq_desc *desc = irq_to_desc(irq);
289 	struct irq_affinity_notify *old_notify;
290 	unsigned long flags;
291 
292 	/* The release function is promised process context */
293 	might_sleep();
294 
295 	if (!desc)
296 		return -EINVAL;
297 
298 	/* Complete initialisation of *notify */
299 	if (notify) {
300 		notify->irq = irq;
301 		kref_init(&notify->kref);
302 		INIT_WORK(&notify->work, irq_affinity_notify);
303 	}
304 
305 	raw_spin_lock_irqsave(&desc->lock, flags);
306 	old_notify = desc->affinity_notify;
307 	desc->affinity_notify = notify;
308 	raw_spin_unlock_irqrestore(&desc->lock, flags);
309 
310 	if (old_notify)
311 		kref_put(&old_notify->kref, old_notify->release);
312 
313 	return 0;
314 }
315 EXPORT_SYMBOL_GPL(irq_set_affinity_notifier);
316 
317 #ifndef CONFIG_AUTO_IRQ_AFFINITY
318 /*
319  * Generic version of the affinity autoselector.
320  */
321 static int
322 setup_affinity(unsigned int irq, struct irq_desc *desc, struct cpumask *mask)
323 {
324 	struct cpumask *set = irq_default_affinity;
325 	int node = desc->irq_data.node;
326 
327 	/* Excludes PER_CPU and NO_BALANCE interrupts */
328 	if (!irq_can_set_affinity(irq))
329 		return 0;
330 
331 	/*
332 	 * Preserve an userspace affinity setup, but make sure that
333 	 * one of the targets is online.
334 	 */
335 	if (irqd_has_set(&desc->irq_data, IRQD_AFFINITY_SET)) {
336 		if (cpumask_intersects(desc->irq_data.affinity,
337 				       cpu_online_mask))
338 			set = desc->irq_data.affinity;
339 		else
340 			irqd_clear(&desc->irq_data, IRQD_AFFINITY_SET);
341 	}
342 
343 	cpumask_and(mask, cpu_online_mask, set);
344 	if (node != NUMA_NO_NODE) {
345 		const struct cpumask *nodemask = cpumask_of_node(node);
346 
347 		/* make sure at least one of the cpus in nodemask is online */
348 		if (cpumask_intersects(mask, nodemask))
349 			cpumask_and(mask, mask, nodemask);
350 	}
351 	irq_do_set_affinity(&desc->irq_data, mask, false);
352 	return 0;
353 }
354 #else
355 static inline int
356 setup_affinity(unsigned int irq, struct irq_desc *d, struct cpumask *mask)
357 {
358 	return irq_select_affinity(irq);
359 }
360 #endif
361 
362 /*
363  * Called when affinity is set via /proc/irq
364  */
365 int irq_select_affinity_usr(unsigned int irq, struct cpumask *mask)
366 {
367 	struct irq_desc *desc = irq_to_desc(irq);
368 	unsigned long flags;
369 	int ret;
370 
371 	raw_spin_lock_irqsave(&desc->lock, flags);
372 	ret = setup_affinity(irq, desc, mask);
373 	raw_spin_unlock_irqrestore(&desc->lock, flags);
374 	return ret;
375 }
376 
377 #else
378 static inline int
379 setup_affinity(unsigned int irq, struct irq_desc *desc, struct cpumask *mask)
380 {
381 	return 0;
382 }
383 #endif
384 
385 void __disable_irq(struct irq_desc *desc, unsigned int irq)
386 {
387 	if (!desc->depth++)
388 		irq_disable(desc);
389 }
390 
391 static int __disable_irq_nosync(unsigned int irq)
392 {
393 	unsigned long flags;
394 	struct irq_desc *desc = irq_get_desc_buslock(irq, &flags, IRQ_GET_DESC_CHECK_GLOBAL);
395 
396 	if (!desc)
397 		return -EINVAL;
398 	__disable_irq(desc, irq);
399 	irq_put_desc_busunlock(desc, flags);
400 	return 0;
401 }
402 
403 /**
404  *	disable_irq_nosync - disable an irq without waiting
405  *	@irq: Interrupt to disable
406  *
407  *	Disable the selected interrupt line.  Disables and Enables are
408  *	nested.
409  *	Unlike disable_irq(), this function does not ensure existing
410  *	instances of the IRQ handler have completed before returning.
411  *
412  *	This function may be called from IRQ context.
413  */
414 void disable_irq_nosync(unsigned int irq)
415 {
416 	__disable_irq_nosync(irq);
417 }
418 EXPORT_SYMBOL(disable_irq_nosync);
419 
420 /**
421  *	disable_irq - disable an irq and wait for completion
422  *	@irq: Interrupt to disable
423  *
424  *	Disable the selected interrupt line.  Enables and Disables are
425  *	nested.
426  *	This function waits for any pending IRQ handlers for this interrupt
427  *	to complete before returning. If you use this function while
428  *	holding a resource the IRQ handler may need you will deadlock.
429  *
430  *	This function may be called - with care - from IRQ context.
431  */
432 void disable_irq(unsigned int irq)
433 {
434 	if (!__disable_irq_nosync(irq))
435 		synchronize_irq(irq);
436 }
437 EXPORT_SYMBOL(disable_irq);
438 
439 void __enable_irq(struct irq_desc *desc, unsigned int irq)
440 {
441 	switch (desc->depth) {
442 	case 0:
443  err_out:
444 		WARN(1, KERN_WARNING "Unbalanced enable for IRQ %d\n", irq);
445 		break;
446 	case 1: {
447 		if (desc->istate & IRQS_SUSPENDED)
448 			goto err_out;
449 		/* Prevent probing on this irq: */
450 		irq_settings_set_noprobe(desc);
451 		irq_enable(desc);
452 		check_irq_resend(desc, irq);
453 		/* fall-through */
454 	}
455 	default:
456 		desc->depth--;
457 	}
458 }
459 
460 /**
461  *	enable_irq - enable handling of an irq
462  *	@irq: Interrupt to enable
463  *
464  *	Undoes the effect of one call to disable_irq().  If this
465  *	matches the last disable, processing of interrupts on this
466  *	IRQ line is re-enabled.
467  *
468  *	This function may be called from IRQ context only when
469  *	desc->irq_data.chip->bus_lock and desc->chip->bus_sync_unlock are NULL !
470  */
471 void enable_irq(unsigned int irq)
472 {
473 	unsigned long flags;
474 	struct irq_desc *desc = irq_get_desc_buslock(irq, &flags, IRQ_GET_DESC_CHECK_GLOBAL);
475 
476 	if (!desc)
477 		return;
478 	if (WARN(!desc->irq_data.chip,
479 		 KERN_ERR "enable_irq before setup/request_irq: irq %u\n", irq))
480 		goto out;
481 
482 	__enable_irq(desc, irq);
483 out:
484 	irq_put_desc_busunlock(desc, flags);
485 }
486 EXPORT_SYMBOL(enable_irq);
487 
488 static int set_irq_wake_real(unsigned int irq, unsigned int on)
489 {
490 	struct irq_desc *desc = irq_to_desc(irq);
491 	int ret = -ENXIO;
492 
493 	if (irq_desc_get_chip(desc)->flags &  IRQCHIP_SKIP_SET_WAKE)
494 		return 0;
495 
496 	if (desc->irq_data.chip->irq_set_wake)
497 		ret = desc->irq_data.chip->irq_set_wake(&desc->irq_data, on);
498 
499 	return ret;
500 }
501 
502 /**
503  *	irq_set_irq_wake - control irq power management wakeup
504  *	@irq:	interrupt to control
505  *	@on:	enable/disable power management wakeup
506  *
507  *	Enable/disable power management wakeup mode, which is
508  *	disabled by default.  Enables and disables must match,
509  *	just as they match for non-wakeup mode support.
510  *
511  *	Wakeup mode lets this IRQ wake the system from sleep
512  *	states like "suspend to RAM".
513  */
514 int irq_set_irq_wake(unsigned int irq, unsigned int on)
515 {
516 	unsigned long flags;
517 	struct irq_desc *desc = irq_get_desc_buslock(irq, &flags, IRQ_GET_DESC_CHECK_GLOBAL);
518 	int ret = 0;
519 
520 	if (!desc)
521 		return -EINVAL;
522 
523 	/* wakeup-capable irqs can be shared between drivers that
524 	 * don't need to have the same sleep mode behaviors.
525 	 */
526 	if (on) {
527 		if (desc->wake_depth++ == 0) {
528 			ret = set_irq_wake_real(irq, on);
529 			if (ret)
530 				desc->wake_depth = 0;
531 			else
532 				irqd_set(&desc->irq_data, IRQD_WAKEUP_STATE);
533 		}
534 	} else {
535 		if (desc->wake_depth == 0) {
536 			WARN(1, "Unbalanced IRQ %d wake disable\n", irq);
537 		} else if (--desc->wake_depth == 0) {
538 			ret = set_irq_wake_real(irq, on);
539 			if (ret)
540 				desc->wake_depth = 1;
541 			else
542 				irqd_clear(&desc->irq_data, IRQD_WAKEUP_STATE);
543 		}
544 	}
545 	irq_put_desc_busunlock(desc, flags);
546 	return ret;
547 }
548 EXPORT_SYMBOL(irq_set_irq_wake);
549 
550 /*
551  * Internal function that tells the architecture code whether a
552  * particular irq has been exclusively allocated or is available
553  * for driver use.
554  */
555 int can_request_irq(unsigned int irq, unsigned long irqflags)
556 {
557 	unsigned long flags;
558 	struct irq_desc *desc = irq_get_desc_lock(irq, &flags, 0);
559 	int canrequest = 0;
560 
561 	if (!desc)
562 		return 0;
563 
564 	if (irq_settings_can_request(desc)) {
565 		if (!desc->action ||
566 		    irqflags & desc->action->flags & IRQF_SHARED)
567 			canrequest = 1;
568 	}
569 	irq_put_desc_unlock(desc, flags);
570 	return canrequest;
571 }
572 
573 int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
574 		      unsigned long flags)
575 {
576 	struct irq_chip *chip = desc->irq_data.chip;
577 	int ret, unmask = 0;
578 
579 	if (!chip || !chip->irq_set_type) {
580 		/*
581 		 * IRQF_TRIGGER_* but the PIC does not support multiple
582 		 * flow-types?
583 		 */
584 		pr_debug("No set_type function for IRQ %d (%s)\n", irq,
585 			 chip ? (chip->name ? : "unknown") : "unknown");
586 		return 0;
587 	}
588 
589 	flags &= IRQ_TYPE_SENSE_MASK;
590 
591 	if (chip->flags & IRQCHIP_SET_TYPE_MASKED) {
592 		if (!irqd_irq_masked(&desc->irq_data))
593 			mask_irq(desc);
594 		if (!irqd_irq_disabled(&desc->irq_data))
595 			unmask = 1;
596 	}
597 
598 	/* caller masked out all except trigger mode flags */
599 	ret = chip->irq_set_type(&desc->irq_data, flags);
600 
601 	switch (ret) {
602 	case IRQ_SET_MASK_OK:
603 		irqd_clear(&desc->irq_data, IRQD_TRIGGER_MASK);
604 		irqd_set(&desc->irq_data, flags);
605 
606 	case IRQ_SET_MASK_OK_NOCOPY:
607 		flags = irqd_get_trigger_type(&desc->irq_data);
608 		irq_settings_set_trigger_mask(desc, flags);
609 		irqd_clear(&desc->irq_data, IRQD_LEVEL);
610 		irq_settings_clr_level(desc);
611 		if (flags & IRQ_TYPE_LEVEL_MASK) {
612 			irq_settings_set_level(desc);
613 			irqd_set(&desc->irq_data, IRQD_LEVEL);
614 		}
615 
616 		ret = 0;
617 		break;
618 	default:
619 		pr_err("Setting trigger mode %lu for irq %u failed (%pF)\n",
620 		       flags, irq, chip->irq_set_type);
621 	}
622 	if (unmask)
623 		unmask_irq(desc);
624 	return ret;
625 }
626 
627 #ifdef CONFIG_HARDIRQS_SW_RESEND
628 int irq_set_parent(int irq, int parent_irq)
629 {
630 	unsigned long flags;
631 	struct irq_desc *desc = irq_get_desc_lock(irq, &flags, 0);
632 
633 	if (!desc)
634 		return -EINVAL;
635 
636 	desc->parent_irq = parent_irq;
637 
638 	irq_put_desc_unlock(desc, flags);
639 	return 0;
640 }
641 #endif
642 
643 /*
644  * Default primary interrupt handler for threaded interrupts. Is
645  * assigned as primary handler when request_threaded_irq is called
646  * with handler == NULL. Useful for oneshot interrupts.
647  */
648 static irqreturn_t irq_default_primary_handler(int irq, void *dev_id)
649 {
650 	return IRQ_WAKE_THREAD;
651 }
652 
653 /*
654  * Primary handler for nested threaded interrupts. Should never be
655  * called.
656  */
657 static irqreturn_t irq_nested_primary_handler(int irq, void *dev_id)
658 {
659 	WARN(1, "Primary handler called for nested irq %d\n", irq);
660 	return IRQ_NONE;
661 }
662 
663 static int irq_wait_for_interrupt(struct irqaction *action)
664 {
665 	set_current_state(TASK_INTERRUPTIBLE);
666 
667 	while (!kthread_should_stop()) {
668 
669 		if (test_and_clear_bit(IRQTF_RUNTHREAD,
670 				       &action->thread_flags)) {
671 			__set_current_state(TASK_RUNNING);
672 			return 0;
673 		}
674 		schedule();
675 		set_current_state(TASK_INTERRUPTIBLE);
676 	}
677 	__set_current_state(TASK_RUNNING);
678 	return -1;
679 }
680 
681 /*
682  * Oneshot interrupts keep the irq line masked until the threaded
683  * handler finished. unmask if the interrupt has not been disabled and
684  * is marked MASKED.
685  */
686 static void irq_finalize_oneshot(struct irq_desc *desc,
687 				 struct irqaction *action)
688 {
689 	if (!(desc->istate & IRQS_ONESHOT))
690 		return;
691 again:
692 	chip_bus_lock(desc);
693 	raw_spin_lock_irq(&desc->lock);
694 
695 	/*
696 	 * Implausible though it may be we need to protect us against
697 	 * the following scenario:
698 	 *
699 	 * The thread is faster done than the hard interrupt handler
700 	 * on the other CPU. If we unmask the irq line then the
701 	 * interrupt can come in again and masks the line, leaves due
702 	 * to IRQS_INPROGRESS and the irq line is masked forever.
703 	 *
704 	 * This also serializes the state of shared oneshot handlers
705 	 * versus "desc->threads_onehsot |= action->thread_mask;" in
706 	 * irq_wake_thread(). See the comment there which explains the
707 	 * serialization.
708 	 */
709 	if (unlikely(irqd_irq_inprogress(&desc->irq_data))) {
710 		raw_spin_unlock_irq(&desc->lock);
711 		chip_bus_sync_unlock(desc);
712 		cpu_relax();
713 		goto again;
714 	}
715 
716 	/*
717 	 * Now check again, whether the thread should run. Otherwise
718 	 * we would clear the threads_oneshot bit of this thread which
719 	 * was just set.
720 	 */
721 	if (test_bit(IRQTF_RUNTHREAD, &action->thread_flags))
722 		goto out_unlock;
723 
724 	desc->threads_oneshot &= ~action->thread_mask;
725 
726 	if (!desc->threads_oneshot && !irqd_irq_disabled(&desc->irq_data) &&
727 	    irqd_irq_masked(&desc->irq_data))
728 		unmask_threaded_irq(desc);
729 
730 out_unlock:
731 	raw_spin_unlock_irq(&desc->lock);
732 	chip_bus_sync_unlock(desc);
733 }
734 
735 #ifdef CONFIG_SMP
736 /*
737  * Check whether we need to change the affinity of the interrupt thread.
738  */
739 static void
740 irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action)
741 {
742 	cpumask_var_t mask;
743 	bool valid = true;
744 
745 	if (!test_and_clear_bit(IRQTF_AFFINITY, &action->thread_flags))
746 		return;
747 
748 	/*
749 	 * In case we are out of memory we set IRQTF_AFFINITY again and
750 	 * try again next time
751 	 */
752 	if (!alloc_cpumask_var(&mask, GFP_KERNEL)) {
753 		set_bit(IRQTF_AFFINITY, &action->thread_flags);
754 		return;
755 	}
756 
757 	raw_spin_lock_irq(&desc->lock);
758 	/*
759 	 * This code is triggered unconditionally. Check the affinity
760 	 * mask pointer. For CPU_MASK_OFFSTACK=n this is optimized out.
761 	 */
762 	if (desc->irq_data.affinity)
763 		cpumask_copy(mask, desc->irq_data.affinity);
764 	else
765 		valid = false;
766 	raw_spin_unlock_irq(&desc->lock);
767 
768 	if (valid)
769 		set_cpus_allowed_ptr(current, mask);
770 	free_cpumask_var(mask);
771 }
772 #else
773 static inline void
774 irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action) { }
775 #endif
776 
777 /*
778  * Interrupts which are not explicitely requested as threaded
779  * interrupts rely on the implicit bh/preempt disable of the hard irq
780  * context. So we need to disable bh here to avoid deadlocks and other
781  * side effects.
782  */
783 static irqreturn_t
784 irq_forced_thread_fn(struct irq_desc *desc, struct irqaction *action)
785 {
786 	irqreturn_t ret;
787 
788 	local_bh_disable();
789 	ret = action->thread_fn(action->irq, action->dev_id);
790 	irq_finalize_oneshot(desc, action);
791 	local_bh_enable();
792 	return ret;
793 }
794 
795 /*
796  * Interrupts explicitly requested as threaded interrupts want to be
797  * preemtible - many of them need to sleep and wait for slow busses to
798  * complete.
799  */
800 static irqreturn_t irq_thread_fn(struct irq_desc *desc,
801 		struct irqaction *action)
802 {
803 	irqreturn_t ret;
804 
805 	ret = action->thread_fn(action->irq, action->dev_id);
806 	irq_finalize_oneshot(desc, action);
807 	return ret;
808 }
809 
810 static void wake_threads_waitq(struct irq_desc *desc)
811 {
812 	if (atomic_dec_and_test(&desc->threads_active))
813 		wake_up(&desc->wait_for_threads);
814 }
815 
816 static void irq_thread_dtor(struct callback_head *unused)
817 {
818 	struct task_struct *tsk = current;
819 	struct irq_desc *desc;
820 	struct irqaction *action;
821 
822 	if (WARN_ON_ONCE(!(current->flags & PF_EXITING)))
823 		return;
824 
825 	action = kthread_data(tsk);
826 
827 	pr_err("exiting task \"%s\" (%d) is an active IRQ thread (irq %d)\n",
828 	       tsk->comm, tsk->pid, action->irq);
829 
830 
831 	desc = irq_to_desc(action->irq);
832 	/*
833 	 * If IRQTF_RUNTHREAD is set, we need to decrement
834 	 * desc->threads_active and wake possible waiters.
835 	 */
836 	if (test_and_clear_bit(IRQTF_RUNTHREAD, &action->thread_flags))
837 		wake_threads_waitq(desc);
838 
839 	/* Prevent a stale desc->threads_oneshot */
840 	irq_finalize_oneshot(desc, action);
841 }
842 
843 /*
844  * Interrupt handler thread
845  */
846 static int irq_thread(void *data)
847 {
848 	struct callback_head on_exit_work;
849 	struct irqaction *action = data;
850 	struct irq_desc *desc = irq_to_desc(action->irq);
851 	irqreturn_t (*handler_fn)(struct irq_desc *desc,
852 			struct irqaction *action);
853 
854 	if (force_irqthreads && test_bit(IRQTF_FORCED_THREAD,
855 					&action->thread_flags))
856 		handler_fn = irq_forced_thread_fn;
857 	else
858 		handler_fn = irq_thread_fn;
859 
860 	init_task_work(&on_exit_work, irq_thread_dtor);
861 	task_work_add(current, &on_exit_work, false);
862 
863 	irq_thread_check_affinity(desc, action);
864 
865 	while (!irq_wait_for_interrupt(action)) {
866 		irqreturn_t action_ret;
867 
868 		irq_thread_check_affinity(desc, action);
869 
870 		action_ret = handler_fn(desc, action);
871 		if (action_ret == IRQ_HANDLED)
872 			atomic_inc(&desc->threads_handled);
873 
874 		wake_threads_waitq(desc);
875 	}
876 
877 	/*
878 	 * This is the regular exit path. __free_irq() is stopping the
879 	 * thread via kthread_stop() after calling
880 	 * synchronize_irq(). So neither IRQTF_RUNTHREAD nor the
881 	 * oneshot mask bit can be set. We cannot verify that as we
882 	 * cannot touch the oneshot mask at this point anymore as
883 	 * __setup_irq() might have given out currents thread_mask
884 	 * again.
885 	 */
886 	task_work_cancel(current, irq_thread_dtor);
887 	return 0;
888 }
889 
890 /**
891  *	irq_wake_thread - wake the irq thread for the action identified by dev_id
892  *	@irq:		Interrupt line
893  *	@dev_id:	Device identity for which the thread should be woken
894  *
895  */
896 void irq_wake_thread(unsigned int irq, void *dev_id)
897 {
898 	struct irq_desc *desc = irq_to_desc(irq);
899 	struct irqaction *action;
900 	unsigned long flags;
901 
902 	if (!desc || WARN_ON(irq_settings_is_per_cpu_devid(desc)))
903 		return;
904 
905 	raw_spin_lock_irqsave(&desc->lock, flags);
906 	for (action = desc->action; action; action = action->next) {
907 		if (action->dev_id == dev_id) {
908 			if (action->thread)
909 				__irq_wake_thread(desc, action);
910 			break;
911 		}
912 	}
913 	raw_spin_unlock_irqrestore(&desc->lock, flags);
914 }
915 EXPORT_SYMBOL_GPL(irq_wake_thread);
916 
917 static void irq_setup_forced_threading(struct irqaction *new)
918 {
919 	if (!force_irqthreads)
920 		return;
921 	if (new->flags & (IRQF_NO_THREAD | IRQF_PERCPU | IRQF_ONESHOT))
922 		return;
923 
924 	new->flags |= IRQF_ONESHOT;
925 
926 	if (!new->thread_fn) {
927 		set_bit(IRQTF_FORCED_THREAD, &new->thread_flags);
928 		new->thread_fn = new->handler;
929 		new->handler = irq_default_primary_handler;
930 	}
931 }
932 
933 static int irq_request_resources(struct irq_desc *desc)
934 {
935 	struct irq_data *d = &desc->irq_data;
936 	struct irq_chip *c = d->chip;
937 
938 	return c->irq_request_resources ? c->irq_request_resources(d) : 0;
939 }
940 
941 static void irq_release_resources(struct irq_desc *desc)
942 {
943 	struct irq_data *d = &desc->irq_data;
944 	struct irq_chip *c = d->chip;
945 
946 	if (c->irq_release_resources)
947 		c->irq_release_resources(d);
948 }
949 
950 /*
951  * Internal function to register an irqaction - typically used to
952  * allocate special interrupts that are part of the architecture.
953  */
954 static int
955 __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
956 {
957 	struct irqaction *old, **old_ptr;
958 	unsigned long flags, thread_mask = 0;
959 	int ret, nested, shared = 0;
960 	cpumask_var_t mask;
961 
962 	if (!desc)
963 		return -EINVAL;
964 
965 	if (desc->irq_data.chip == &no_irq_chip)
966 		return -ENOSYS;
967 	if (!try_module_get(desc->owner))
968 		return -ENODEV;
969 
970 	/*
971 	 * Check whether the interrupt nests into another interrupt
972 	 * thread.
973 	 */
974 	nested = irq_settings_is_nested_thread(desc);
975 	if (nested) {
976 		if (!new->thread_fn) {
977 			ret = -EINVAL;
978 			goto out_mput;
979 		}
980 		/*
981 		 * Replace the primary handler which was provided from
982 		 * the driver for non nested interrupt handling by the
983 		 * dummy function which warns when called.
984 		 */
985 		new->handler = irq_nested_primary_handler;
986 	} else {
987 		if (irq_settings_can_thread(desc))
988 			irq_setup_forced_threading(new);
989 	}
990 
991 	/*
992 	 * Create a handler thread when a thread function is supplied
993 	 * and the interrupt does not nest into another interrupt
994 	 * thread.
995 	 */
996 	if (new->thread_fn && !nested) {
997 		struct task_struct *t;
998 		static const struct sched_param param = {
999 			.sched_priority = MAX_USER_RT_PRIO/2,
1000 		};
1001 
1002 		t = kthread_create(irq_thread, new, "irq/%d-%s", irq,
1003 				   new->name);
1004 		if (IS_ERR(t)) {
1005 			ret = PTR_ERR(t);
1006 			goto out_mput;
1007 		}
1008 
1009 		sched_setscheduler_nocheck(t, SCHED_FIFO, &param);
1010 
1011 		/*
1012 		 * We keep the reference to the task struct even if
1013 		 * the thread dies to avoid that the interrupt code
1014 		 * references an already freed task_struct.
1015 		 */
1016 		get_task_struct(t);
1017 		new->thread = t;
1018 		/*
1019 		 * Tell the thread to set its affinity. This is
1020 		 * important for shared interrupt handlers as we do
1021 		 * not invoke setup_affinity() for the secondary
1022 		 * handlers as everything is already set up. Even for
1023 		 * interrupts marked with IRQF_NO_BALANCE this is
1024 		 * correct as we want the thread to move to the cpu(s)
1025 		 * on which the requesting code placed the interrupt.
1026 		 */
1027 		set_bit(IRQTF_AFFINITY, &new->thread_flags);
1028 	}
1029 
1030 	if (!alloc_cpumask_var(&mask, GFP_KERNEL)) {
1031 		ret = -ENOMEM;
1032 		goto out_thread;
1033 	}
1034 
1035 	/*
1036 	 * Drivers are often written to work w/o knowledge about the
1037 	 * underlying irq chip implementation, so a request for a
1038 	 * threaded irq without a primary hard irq context handler
1039 	 * requires the ONESHOT flag to be set. Some irq chips like
1040 	 * MSI based interrupts are per se one shot safe. Check the
1041 	 * chip flags, so we can avoid the unmask dance at the end of
1042 	 * the threaded handler for those.
1043 	 */
1044 	if (desc->irq_data.chip->flags & IRQCHIP_ONESHOT_SAFE)
1045 		new->flags &= ~IRQF_ONESHOT;
1046 
1047 	/*
1048 	 * The following block of code has to be executed atomically
1049 	 */
1050 	raw_spin_lock_irqsave(&desc->lock, flags);
1051 	old_ptr = &desc->action;
1052 	old = *old_ptr;
1053 	if (old) {
1054 		/*
1055 		 * Can't share interrupts unless both agree to and are
1056 		 * the same type (level, edge, polarity). So both flag
1057 		 * fields must have IRQF_SHARED set and the bits which
1058 		 * set the trigger type must match. Also all must
1059 		 * agree on ONESHOT.
1060 		 */
1061 		if (!((old->flags & new->flags) & IRQF_SHARED) ||
1062 		    ((old->flags ^ new->flags) & IRQF_TRIGGER_MASK) ||
1063 		    ((old->flags ^ new->flags) & IRQF_ONESHOT))
1064 			goto mismatch;
1065 
1066 		/* All handlers must agree on per-cpuness */
1067 		if ((old->flags & IRQF_PERCPU) !=
1068 		    (new->flags & IRQF_PERCPU))
1069 			goto mismatch;
1070 
1071 		/* add new interrupt at end of irq queue */
1072 		do {
1073 			/*
1074 			 * Or all existing action->thread_mask bits,
1075 			 * so we can find the next zero bit for this
1076 			 * new action.
1077 			 */
1078 			thread_mask |= old->thread_mask;
1079 			old_ptr = &old->next;
1080 			old = *old_ptr;
1081 		} while (old);
1082 		shared = 1;
1083 	}
1084 
1085 	/*
1086 	 * Setup the thread mask for this irqaction for ONESHOT. For
1087 	 * !ONESHOT irqs the thread mask is 0 so we can avoid a
1088 	 * conditional in irq_wake_thread().
1089 	 */
1090 	if (new->flags & IRQF_ONESHOT) {
1091 		/*
1092 		 * Unlikely to have 32 resp 64 irqs sharing one line,
1093 		 * but who knows.
1094 		 */
1095 		if (thread_mask == ~0UL) {
1096 			ret = -EBUSY;
1097 			goto out_mask;
1098 		}
1099 		/*
1100 		 * The thread_mask for the action is or'ed to
1101 		 * desc->thread_active to indicate that the
1102 		 * IRQF_ONESHOT thread handler has been woken, but not
1103 		 * yet finished. The bit is cleared when a thread
1104 		 * completes. When all threads of a shared interrupt
1105 		 * line have completed desc->threads_active becomes
1106 		 * zero and the interrupt line is unmasked. See
1107 		 * handle.c:irq_wake_thread() for further information.
1108 		 *
1109 		 * If no thread is woken by primary (hard irq context)
1110 		 * interrupt handlers, then desc->threads_active is
1111 		 * also checked for zero to unmask the irq line in the
1112 		 * affected hard irq flow handlers
1113 		 * (handle_[fasteoi|level]_irq).
1114 		 *
1115 		 * The new action gets the first zero bit of
1116 		 * thread_mask assigned. See the loop above which or's
1117 		 * all existing action->thread_mask bits.
1118 		 */
1119 		new->thread_mask = 1 << ffz(thread_mask);
1120 
1121 	} else if (new->handler == irq_default_primary_handler &&
1122 		   !(desc->irq_data.chip->flags & IRQCHIP_ONESHOT_SAFE)) {
1123 		/*
1124 		 * The interrupt was requested with handler = NULL, so
1125 		 * we use the default primary handler for it. But it
1126 		 * does not have the oneshot flag set. In combination
1127 		 * with level interrupts this is deadly, because the
1128 		 * default primary handler just wakes the thread, then
1129 		 * the irq lines is reenabled, but the device still
1130 		 * has the level irq asserted. Rinse and repeat....
1131 		 *
1132 		 * While this works for edge type interrupts, we play
1133 		 * it safe and reject unconditionally because we can't
1134 		 * say for sure which type this interrupt really
1135 		 * has. The type flags are unreliable as the
1136 		 * underlying chip implementation can override them.
1137 		 */
1138 		pr_err("Threaded irq requested with handler=NULL and !ONESHOT for irq %d\n",
1139 		       irq);
1140 		ret = -EINVAL;
1141 		goto out_mask;
1142 	}
1143 
1144 	if (!shared) {
1145 		ret = irq_request_resources(desc);
1146 		if (ret) {
1147 			pr_err("Failed to request resources for %s (irq %d) on irqchip %s\n",
1148 			       new->name, irq, desc->irq_data.chip->name);
1149 			goto out_mask;
1150 		}
1151 
1152 		init_waitqueue_head(&desc->wait_for_threads);
1153 
1154 		/* Setup the type (level, edge polarity) if configured: */
1155 		if (new->flags & IRQF_TRIGGER_MASK) {
1156 			ret = __irq_set_trigger(desc, irq,
1157 					new->flags & IRQF_TRIGGER_MASK);
1158 
1159 			if (ret)
1160 				goto out_mask;
1161 		}
1162 
1163 		desc->istate &= ~(IRQS_AUTODETECT | IRQS_SPURIOUS_DISABLED | \
1164 				  IRQS_ONESHOT | IRQS_WAITING);
1165 		irqd_clear(&desc->irq_data, IRQD_IRQ_INPROGRESS);
1166 
1167 		if (new->flags & IRQF_PERCPU) {
1168 			irqd_set(&desc->irq_data, IRQD_PER_CPU);
1169 			irq_settings_set_per_cpu(desc);
1170 		}
1171 
1172 		if (new->flags & IRQF_ONESHOT)
1173 			desc->istate |= IRQS_ONESHOT;
1174 
1175 		if (irq_settings_can_autoenable(desc))
1176 			irq_startup(desc, true);
1177 		else
1178 			/* Undo nested disables: */
1179 			desc->depth = 1;
1180 
1181 		/* Exclude IRQ from balancing if requested */
1182 		if (new->flags & IRQF_NOBALANCING) {
1183 			irq_settings_set_no_balancing(desc);
1184 			irqd_set(&desc->irq_data, IRQD_NO_BALANCING);
1185 		}
1186 
1187 		/* Set default affinity mask once everything is setup */
1188 		setup_affinity(irq, desc, mask);
1189 
1190 	} else if (new->flags & IRQF_TRIGGER_MASK) {
1191 		unsigned int nmsk = new->flags & IRQF_TRIGGER_MASK;
1192 		unsigned int omsk = irq_settings_get_trigger_mask(desc);
1193 
1194 		if (nmsk != omsk)
1195 			/* hope the handler works with current  trigger mode */
1196 			pr_warning("irq %d uses trigger mode %u; requested %u\n",
1197 				   irq, nmsk, omsk);
1198 	}
1199 
1200 	new->irq = irq;
1201 	*old_ptr = new;
1202 
1203 	irq_pm_install_action(desc, new);
1204 
1205 	/* Reset broken irq detection when installing new handler */
1206 	desc->irq_count = 0;
1207 	desc->irqs_unhandled = 0;
1208 
1209 	/*
1210 	 * Check whether we disabled the irq via the spurious handler
1211 	 * before. Reenable it and give it another chance.
1212 	 */
1213 	if (shared && (desc->istate & IRQS_SPURIOUS_DISABLED)) {
1214 		desc->istate &= ~IRQS_SPURIOUS_DISABLED;
1215 		__enable_irq(desc, irq);
1216 	}
1217 
1218 	raw_spin_unlock_irqrestore(&desc->lock, flags);
1219 
1220 	/*
1221 	 * Strictly no need to wake it up, but hung_task complains
1222 	 * when no hard interrupt wakes the thread up.
1223 	 */
1224 	if (new->thread)
1225 		wake_up_process(new->thread);
1226 
1227 	register_irq_proc(irq, desc);
1228 	new->dir = NULL;
1229 	register_handler_proc(irq, new);
1230 	free_cpumask_var(mask);
1231 
1232 	return 0;
1233 
1234 mismatch:
1235 	if (!(new->flags & IRQF_PROBE_SHARED)) {
1236 		pr_err("Flags mismatch irq %d. %08x (%s) vs. %08x (%s)\n",
1237 		       irq, new->flags, new->name, old->flags, old->name);
1238 #ifdef CONFIG_DEBUG_SHIRQ
1239 		dump_stack();
1240 #endif
1241 	}
1242 	ret = -EBUSY;
1243 
1244 out_mask:
1245 	raw_spin_unlock_irqrestore(&desc->lock, flags);
1246 	free_cpumask_var(mask);
1247 
1248 out_thread:
1249 	if (new->thread) {
1250 		struct task_struct *t = new->thread;
1251 
1252 		new->thread = NULL;
1253 		kthread_stop(t);
1254 		put_task_struct(t);
1255 	}
1256 out_mput:
1257 	module_put(desc->owner);
1258 	return ret;
1259 }
1260 
1261 /**
1262  *	setup_irq - setup an interrupt
1263  *	@irq: Interrupt line to setup
1264  *	@act: irqaction for the interrupt
1265  *
1266  * Used to statically setup interrupts in the early boot process.
1267  */
1268 int setup_irq(unsigned int irq, struct irqaction *act)
1269 {
1270 	int retval;
1271 	struct irq_desc *desc = irq_to_desc(irq);
1272 
1273 	if (WARN_ON(irq_settings_is_per_cpu_devid(desc)))
1274 		return -EINVAL;
1275 	chip_bus_lock(desc);
1276 	retval = __setup_irq(irq, desc, act);
1277 	chip_bus_sync_unlock(desc);
1278 
1279 	return retval;
1280 }
1281 EXPORT_SYMBOL_GPL(setup_irq);
1282 
1283 /*
1284  * Internal function to unregister an irqaction - used to free
1285  * regular and special interrupts that are part of the architecture.
1286  */
1287 static struct irqaction *__free_irq(unsigned int irq, void *dev_id)
1288 {
1289 	struct irq_desc *desc = irq_to_desc(irq);
1290 	struct irqaction *action, **action_ptr;
1291 	unsigned long flags;
1292 
1293 	WARN(in_interrupt(), "Trying to free IRQ %d from IRQ context!\n", irq);
1294 
1295 	if (!desc)
1296 		return NULL;
1297 
1298 	raw_spin_lock_irqsave(&desc->lock, flags);
1299 
1300 	/*
1301 	 * There can be multiple actions per IRQ descriptor, find the right
1302 	 * one based on the dev_id:
1303 	 */
1304 	action_ptr = &desc->action;
1305 	for (;;) {
1306 		action = *action_ptr;
1307 
1308 		if (!action) {
1309 			WARN(1, "Trying to free already-free IRQ %d\n", irq);
1310 			raw_spin_unlock_irqrestore(&desc->lock, flags);
1311 
1312 			return NULL;
1313 		}
1314 
1315 		if (action->dev_id == dev_id)
1316 			break;
1317 		action_ptr = &action->next;
1318 	}
1319 
1320 	/* Found it - now remove it from the list of entries: */
1321 	*action_ptr = action->next;
1322 
1323 	irq_pm_remove_action(desc, action);
1324 
1325 	/* If this was the last handler, shut down the IRQ line: */
1326 	if (!desc->action) {
1327 		irq_shutdown(desc);
1328 		irq_release_resources(desc);
1329 	}
1330 
1331 #ifdef CONFIG_SMP
1332 	/* make sure affinity_hint is cleaned up */
1333 	if (WARN_ON_ONCE(desc->affinity_hint))
1334 		desc->affinity_hint = NULL;
1335 #endif
1336 
1337 	raw_spin_unlock_irqrestore(&desc->lock, flags);
1338 
1339 	unregister_handler_proc(irq, action);
1340 
1341 	/* Make sure it's not being used on another CPU: */
1342 	synchronize_irq(irq);
1343 
1344 #ifdef CONFIG_DEBUG_SHIRQ
1345 	/*
1346 	 * It's a shared IRQ -- the driver ought to be prepared for an IRQ
1347 	 * event to happen even now it's being freed, so let's make sure that
1348 	 * is so by doing an extra call to the handler ....
1349 	 *
1350 	 * ( We do this after actually deregistering it, to make sure that a
1351 	 *   'real' IRQ doesn't run in * parallel with our fake. )
1352 	 */
1353 	if (action->flags & IRQF_SHARED) {
1354 		local_irq_save(flags);
1355 		action->handler(irq, dev_id);
1356 		local_irq_restore(flags);
1357 	}
1358 #endif
1359 
1360 	if (action->thread) {
1361 		kthread_stop(action->thread);
1362 		put_task_struct(action->thread);
1363 	}
1364 
1365 	module_put(desc->owner);
1366 	return action;
1367 }
1368 
1369 /**
1370  *	remove_irq - free an interrupt
1371  *	@irq: Interrupt line to free
1372  *	@act: irqaction for the interrupt
1373  *
1374  * Used to remove interrupts statically setup by the early boot process.
1375  */
1376 void remove_irq(unsigned int irq, struct irqaction *act)
1377 {
1378 	struct irq_desc *desc = irq_to_desc(irq);
1379 
1380 	if (desc && !WARN_ON(irq_settings_is_per_cpu_devid(desc)))
1381 	    __free_irq(irq, act->dev_id);
1382 }
1383 EXPORT_SYMBOL_GPL(remove_irq);
1384 
1385 /**
1386  *	free_irq - free an interrupt allocated with request_irq
1387  *	@irq: Interrupt line to free
1388  *	@dev_id: Device identity to free
1389  *
1390  *	Remove an interrupt handler. The handler is removed and if the
1391  *	interrupt line is no longer in use by any driver it is disabled.
1392  *	On a shared IRQ the caller must ensure the interrupt is disabled
1393  *	on the card it drives before calling this function. The function
1394  *	does not return until any executing interrupts for this IRQ
1395  *	have completed.
1396  *
1397  *	This function must not be called from interrupt context.
1398  */
1399 void free_irq(unsigned int irq, void *dev_id)
1400 {
1401 	struct irq_desc *desc = irq_to_desc(irq);
1402 
1403 	if (!desc || WARN_ON(irq_settings_is_per_cpu_devid(desc)))
1404 		return;
1405 
1406 #ifdef CONFIG_SMP
1407 	if (WARN_ON(desc->affinity_notify))
1408 		desc->affinity_notify = NULL;
1409 #endif
1410 
1411 	chip_bus_lock(desc);
1412 	kfree(__free_irq(irq, dev_id));
1413 	chip_bus_sync_unlock(desc);
1414 }
1415 EXPORT_SYMBOL(free_irq);
1416 
1417 /**
1418  *	request_threaded_irq - allocate an interrupt line
1419  *	@irq: Interrupt line to allocate
1420  *	@handler: Function to be called when the IRQ occurs.
1421  *		  Primary handler for threaded interrupts
1422  *		  If NULL and thread_fn != NULL the default
1423  *		  primary handler is installed
1424  *	@thread_fn: Function called from the irq handler thread
1425  *		    If NULL, no irq thread is created
1426  *	@irqflags: Interrupt type flags
1427  *	@devname: An ascii name for the claiming device
1428  *	@dev_id: A cookie passed back to the handler function
1429  *
1430  *	This call allocates interrupt resources and enables the
1431  *	interrupt line and IRQ handling. From the point this
1432  *	call is made your handler function may be invoked. Since
1433  *	your handler function must clear any interrupt the board
1434  *	raises, you must take care both to initialise your hardware
1435  *	and to set up the interrupt handler in the right order.
1436  *
1437  *	If you want to set up a threaded irq handler for your device
1438  *	then you need to supply @handler and @thread_fn. @handler is
1439  *	still called in hard interrupt context and has to check
1440  *	whether the interrupt originates from the device. If yes it
1441  *	needs to disable the interrupt on the device and return
1442  *	IRQ_WAKE_THREAD which will wake up the handler thread and run
1443  *	@thread_fn. This split handler design is necessary to support
1444  *	shared interrupts.
1445  *
1446  *	Dev_id must be globally unique. Normally the address of the
1447  *	device data structure is used as the cookie. Since the handler
1448  *	receives this value it makes sense to use it.
1449  *
1450  *	If your interrupt is shared you must pass a non NULL dev_id
1451  *	as this is required when freeing the interrupt.
1452  *
1453  *	Flags:
1454  *
1455  *	IRQF_SHARED		Interrupt is shared
1456  *	IRQF_TRIGGER_*		Specify active edge(s) or level
1457  *
1458  */
1459 int request_threaded_irq(unsigned int irq, irq_handler_t handler,
1460 			 irq_handler_t thread_fn, unsigned long irqflags,
1461 			 const char *devname, void *dev_id)
1462 {
1463 	struct irqaction *action;
1464 	struct irq_desc *desc;
1465 	int retval;
1466 
1467 	/*
1468 	 * Sanity-check: shared interrupts must pass in a real dev-ID,
1469 	 * otherwise we'll have trouble later trying to figure out
1470 	 * which interrupt is which (messes up the interrupt freeing
1471 	 * logic etc).
1472 	 */
1473 	if ((irqflags & IRQF_SHARED) && !dev_id)
1474 		return -EINVAL;
1475 
1476 	desc = irq_to_desc(irq);
1477 	if (!desc)
1478 		return -EINVAL;
1479 
1480 	if (!irq_settings_can_request(desc) ||
1481 	    WARN_ON(irq_settings_is_per_cpu_devid(desc)))
1482 		return -EINVAL;
1483 
1484 	if (!handler) {
1485 		if (!thread_fn)
1486 			return -EINVAL;
1487 		handler = irq_default_primary_handler;
1488 	}
1489 
1490 	action = kzalloc(sizeof(struct irqaction), GFP_KERNEL);
1491 	if (!action)
1492 		return -ENOMEM;
1493 
1494 	action->handler = handler;
1495 	action->thread_fn = thread_fn;
1496 	action->flags = irqflags;
1497 	action->name = devname;
1498 	action->dev_id = dev_id;
1499 
1500 	chip_bus_lock(desc);
1501 	retval = __setup_irq(irq, desc, action);
1502 	chip_bus_sync_unlock(desc);
1503 
1504 	if (retval)
1505 		kfree(action);
1506 
1507 #ifdef CONFIG_DEBUG_SHIRQ_FIXME
1508 	if (!retval && (irqflags & IRQF_SHARED)) {
1509 		/*
1510 		 * It's a shared IRQ -- the driver ought to be prepared for it
1511 		 * to happen immediately, so let's make sure....
1512 		 * We disable the irq to make sure that a 'real' IRQ doesn't
1513 		 * run in parallel with our fake.
1514 		 */
1515 		unsigned long flags;
1516 
1517 		disable_irq(irq);
1518 		local_irq_save(flags);
1519 
1520 		handler(irq, dev_id);
1521 
1522 		local_irq_restore(flags);
1523 		enable_irq(irq);
1524 	}
1525 #endif
1526 	return retval;
1527 }
1528 EXPORT_SYMBOL(request_threaded_irq);
1529 
1530 /**
1531  *	request_any_context_irq - allocate an interrupt line
1532  *	@irq: Interrupt line to allocate
1533  *	@handler: Function to be called when the IRQ occurs.
1534  *		  Threaded handler for threaded interrupts.
1535  *	@flags: Interrupt type flags
1536  *	@name: An ascii name for the claiming device
1537  *	@dev_id: A cookie passed back to the handler function
1538  *
1539  *	This call allocates interrupt resources and enables the
1540  *	interrupt line and IRQ handling. It selects either a
1541  *	hardirq or threaded handling method depending on the
1542  *	context.
1543  *
1544  *	On failure, it returns a negative value. On success,
1545  *	it returns either IRQC_IS_HARDIRQ or IRQC_IS_NESTED.
1546  */
1547 int request_any_context_irq(unsigned int irq, irq_handler_t handler,
1548 			    unsigned long flags, const char *name, void *dev_id)
1549 {
1550 	struct irq_desc *desc = irq_to_desc(irq);
1551 	int ret;
1552 
1553 	if (!desc)
1554 		return -EINVAL;
1555 
1556 	if (irq_settings_is_nested_thread(desc)) {
1557 		ret = request_threaded_irq(irq, NULL, handler,
1558 					   flags, name, dev_id);
1559 		return !ret ? IRQC_IS_NESTED : ret;
1560 	}
1561 
1562 	ret = request_irq(irq, handler, flags, name, dev_id);
1563 	return !ret ? IRQC_IS_HARDIRQ : ret;
1564 }
1565 EXPORT_SYMBOL_GPL(request_any_context_irq);
1566 
1567 void enable_percpu_irq(unsigned int irq, unsigned int type)
1568 {
1569 	unsigned int cpu = smp_processor_id();
1570 	unsigned long flags;
1571 	struct irq_desc *desc = irq_get_desc_lock(irq, &flags, IRQ_GET_DESC_CHECK_PERCPU);
1572 
1573 	if (!desc)
1574 		return;
1575 
1576 	type &= IRQ_TYPE_SENSE_MASK;
1577 	if (type != IRQ_TYPE_NONE) {
1578 		int ret;
1579 
1580 		ret = __irq_set_trigger(desc, irq, type);
1581 
1582 		if (ret) {
1583 			WARN(1, "failed to set type for IRQ%d\n", irq);
1584 			goto out;
1585 		}
1586 	}
1587 
1588 	irq_percpu_enable(desc, cpu);
1589 out:
1590 	irq_put_desc_unlock(desc, flags);
1591 }
1592 EXPORT_SYMBOL_GPL(enable_percpu_irq);
1593 
1594 void disable_percpu_irq(unsigned int irq)
1595 {
1596 	unsigned int cpu = smp_processor_id();
1597 	unsigned long flags;
1598 	struct irq_desc *desc = irq_get_desc_lock(irq, &flags, IRQ_GET_DESC_CHECK_PERCPU);
1599 
1600 	if (!desc)
1601 		return;
1602 
1603 	irq_percpu_disable(desc, cpu);
1604 	irq_put_desc_unlock(desc, flags);
1605 }
1606 EXPORT_SYMBOL_GPL(disable_percpu_irq);
1607 
1608 /*
1609  * Internal function to unregister a percpu irqaction.
1610  */
1611 static struct irqaction *__free_percpu_irq(unsigned int irq, void __percpu *dev_id)
1612 {
1613 	struct irq_desc *desc = irq_to_desc(irq);
1614 	struct irqaction *action;
1615 	unsigned long flags;
1616 
1617 	WARN(in_interrupt(), "Trying to free IRQ %d from IRQ context!\n", irq);
1618 
1619 	if (!desc)
1620 		return NULL;
1621 
1622 	raw_spin_lock_irqsave(&desc->lock, flags);
1623 
1624 	action = desc->action;
1625 	if (!action || action->percpu_dev_id != dev_id) {
1626 		WARN(1, "Trying to free already-free IRQ %d\n", irq);
1627 		goto bad;
1628 	}
1629 
1630 	if (!cpumask_empty(desc->percpu_enabled)) {
1631 		WARN(1, "percpu IRQ %d still enabled on CPU%d!\n",
1632 		     irq, cpumask_first(desc->percpu_enabled));
1633 		goto bad;
1634 	}
1635 
1636 	/* Found it - now remove it from the list of entries: */
1637 	desc->action = NULL;
1638 
1639 	raw_spin_unlock_irqrestore(&desc->lock, flags);
1640 
1641 	unregister_handler_proc(irq, action);
1642 
1643 	module_put(desc->owner);
1644 	return action;
1645 
1646 bad:
1647 	raw_spin_unlock_irqrestore(&desc->lock, flags);
1648 	return NULL;
1649 }
1650 
1651 /**
1652  *	remove_percpu_irq - free a per-cpu interrupt
1653  *	@irq: Interrupt line to free
1654  *	@act: irqaction for the interrupt
1655  *
1656  * Used to remove interrupts statically setup by the early boot process.
1657  */
1658 void remove_percpu_irq(unsigned int irq, struct irqaction *act)
1659 {
1660 	struct irq_desc *desc = irq_to_desc(irq);
1661 
1662 	if (desc && irq_settings_is_per_cpu_devid(desc))
1663 	    __free_percpu_irq(irq, act->percpu_dev_id);
1664 }
1665 
1666 /**
1667  *	free_percpu_irq - free an interrupt allocated with request_percpu_irq
1668  *	@irq: Interrupt line to free
1669  *	@dev_id: Device identity to free
1670  *
1671  *	Remove a percpu interrupt handler. The handler is removed, but
1672  *	the interrupt line is not disabled. This must be done on each
1673  *	CPU before calling this function. The function does not return
1674  *	until any executing interrupts for this IRQ have completed.
1675  *
1676  *	This function must not be called from interrupt context.
1677  */
1678 void free_percpu_irq(unsigned int irq, void __percpu *dev_id)
1679 {
1680 	struct irq_desc *desc = irq_to_desc(irq);
1681 
1682 	if (!desc || !irq_settings_is_per_cpu_devid(desc))
1683 		return;
1684 
1685 	chip_bus_lock(desc);
1686 	kfree(__free_percpu_irq(irq, dev_id));
1687 	chip_bus_sync_unlock(desc);
1688 }
1689 
1690 /**
1691  *	setup_percpu_irq - setup a per-cpu interrupt
1692  *	@irq: Interrupt line to setup
1693  *	@act: irqaction for the interrupt
1694  *
1695  * Used to statically setup per-cpu interrupts in the early boot process.
1696  */
1697 int setup_percpu_irq(unsigned int irq, struct irqaction *act)
1698 {
1699 	struct irq_desc *desc = irq_to_desc(irq);
1700 	int retval;
1701 
1702 	if (!desc || !irq_settings_is_per_cpu_devid(desc))
1703 		return -EINVAL;
1704 	chip_bus_lock(desc);
1705 	retval = __setup_irq(irq, desc, act);
1706 	chip_bus_sync_unlock(desc);
1707 
1708 	return retval;
1709 }
1710 
1711 /**
1712  *	request_percpu_irq - allocate a percpu interrupt line
1713  *	@irq: Interrupt line to allocate
1714  *	@handler: Function to be called when the IRQ occurs.
1715  *	@devname: An ascii name for the claiming device
1716  *	@dev_id: A percpu cookie passed back to the handler function
1717  *
1718  *	This call allocates interrupt resources, but doesn't
1719  *	automatically enable the interrupt. It has to be done on each
1720  *	CPU using enable_percpu_irq().
1721  *
1722  *	Dev_id must be globally unique. It is a per-cpu variable, and
1723  *	the handler gets called with the interrupted CPU's instance of
1724  *	that variable.
1725  */
1726 int request_percpu_irq(unsigned int irq, irq_handler_t handler,
1727 		       const char *devname, void __percpu *dev_id)
1728 {
1729 	struct irqaction *action;
1730 	struct irq_desc *desc;
1731 	int retval;
1732 
1733 	if (!dev_id)
1734 		return -EINVAL;
1735 
1736 	desc = irq_to_desc(irq);
1737 	if (!desc || !irq_settings_can_request(desc) ||
1738 	    !irq_settings_is_per_cpu_devid(desc))
1739 		return -EINVAL;
1740 
1741 	action = kzalloc(sizeof(struct irqaction), GFP_KERNEL);
1742 	if (!action)
1743 		return -ENOMEM;
1744 
1745 	action->handler = handler;
1746 	action->flags = IRQF_PERCPU | IRQF_NO_SUSPEND;
1747 	action->name = devname;
1748 	action->percpu_dev_id = dev_id;
1749 
1750 	chip_bus_lock(desc);
1751 	retval = __setup_irq(irq, desc, action);
1752 	chip_bus_sync_unlock(desc);
1753 
1754 	if (retval)
1755 		kfree(action);
1756 
1757 	return retval;
1758 }
1759