xref: /openbmc/linux/kernel/irq/manage.c (revision b6bec26c)
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/task_work.h>
20 
21 #include "internals.h"
22 
23 #ifdef CONFIG_IRQ_FORCED_THREADING
24 __read_mostly bool force_irqthreads;
25 
26 static int __init setup_forced_irqthreads(char *arg)
27 {
28 	force_irqthreads = true;
29 	return 0;
30 }
31 early_param("threadirqs", setup_forced_irqthreads);
32 #endif
33 
34 /**
35  *	synchronize_irq - wait for pending IRQ handlers (on other CPUs)
36  *	@irq: interrupt number to wait for
37  *
38  *	This function waits for any pending IRQ handlers for this interrupt
39  *	to complete before returning. If you use this function while
40  *	holding a resource the IRQ handler may need you will deadlock.
41  *
42  *	This function may be called - with care - from IRQ context.
43  */
44 void synchronize_irq(unsigned int irq)
45 {
46 	struct irq_desc *desc = irq_to_desc(irq);
47 	bool inprogress;
48 
49 	if (!desc)
50 		return;
51 
52 	do {
53 		unsigned long flags;
54 
55 		/*
56 		 * Wait until we're out of the critical section.  This might
57 		 * give the wrong answer due to the lack of memory barriers.
58 		 */
59 		while (irqd_irq_inprogress(&desc->irq_data))
60 			cpu_relax();
61 
62 		/* Ok, that indicated we're done: double-check carefully. */
63 		raw_spin_lock_irqsave(&desc->lock, flags);
64 		inprogress = irqd_irq_inprogress(&desc->irq_data);
65 		raw_spin_unlock_irqrestore(&desc->lock, flags);
66 
67 		/* Oops, that failed? */
68 	} while (inprogress);
69 
70 	/*
71 	 * We made sure that no hardirq handler is running. Now verify
72 	 * that no threaded handlers are active.
73 	 */
74 	wait_event(desc->wait_for_threads, !atomic_read(&desc->threads_active));
75 }
76 EXPORT_SYMBOL(synchronize_irq);
77 
78 #ifdef CONFIG_SMP
79 cpumask_var_t irq_default_affinity;
80 
81 /**
82  *	irq_can_set_affinity - Check if the affinity of a given irq can be set
83  *	@irq:		Interrupt to check
84  *
85  */
86 int irq_can_set_affinity(unsigned int irq)
87 {
88 	struct irq_desc *desc = irq_to_desc(irq);
89 
90 	if (!desc || !irqd_can_balance(&desc->irq_data) ||
91 	    !desc->irq_data.chip || !desc->irq_data.chip->irq_set_affinity)
92 		return 0;
93 
94 	return 1;
95 }
96 
97 /**
98  *	irq_set_thread_affinity - Notify irq threads to adjust affinity
99  *	@desc:		irq descriptor which has affitnity changed
100  *
101  *	We just set IRQTF_AFFINITY and delegate the affinity setting
102  *	to the interrupt thread itself. We can not call
103  *	set_cpus_allowed_ptr() here as we hold desc->lock and this
104  *	code can be called from hard interrupt context.
105  */
106 void irq_set_thread_affinity(struct irq_desc *desc)
107 {
108 	struct irqaction *action = desc->action;
109 
110 	while (action) {
111 		if (action->thread)
112 			set_bit(IRQTF_AFFINITY, &action->thread_flags);
113 		action = action->next;
114 	}
115 }
116 
117 #ifdef CONFIG_GENERIC_PENDING_IRQ
118 static inline bool irq_can_move_pcntxt(struct irq_data *data)
119 {
120 	return irqd_can_move_in_process_context(data);
121 }
122 static inline bool irq_move_pending(struct irq_data *data)
123 {
124 	return irqd_is_setaffinity_pending(data);
125 }
126 static inline void
127 irq_copy_pending(struct irq_desc *desc, const struct cpumask *mask)
128 {
129 	cpumask_copy(desc->pending_mask, mask);
130 }
131 static inline void
132 irq_get_pending(struct cpumask *mask, struct irq_desc *desc)
133 {
134 	cpumask_copy(mask, desc->pending_mask);
135 }
136 #else
137 static inline bool irq_can_move_pcntxt(struct irq_data *data) { return true; }
138 static inline bool irq_move_pending(struct irq_data *data) { return false; }
139 static inline void
140 irq_copy_pending(struct irq_desc *desc, const struct cpumask *mask) { }
141 static inline void
142 irq_get_pending(struct cpumask *mask, struct irq_desc *desc) { }
143 #endif
144 
145 int irq_do_set_affinity(struct irq_data *data, const struct cpumask *mask,
146 			bool force)
147 {
148 	struct irq_desc *desc = irq_data_to_desc(data);
149 	struct irq_chip *chip = irq_data_get_irq_chip(data);
150 	int ret;
151 
152 	ret = chip->irq_set_affinity(data, mask, false);
153 	switch (ret) {
154 	case IRQ_SET_MASK_OK:
155 		cpumask_copy(data->affinity, mask);
156 	case IRQ_SET_MASK_OK_NOCOPY:
157 		irq_set_thread_affinity(desc);
158 		ret = 0;
159 	}
160 
161 	return ret;
162 }
163 
164 int __irq_set_affinity_locked(struct irq_data *data, const struct cpumask *mask)
165 {
166 	struct irq_chip *chip = irq_data_get_irq_chip(data);
167 	struct irq_desc *desc = irq_data_to_desc(data);
168 	int ret = 0;
169 
170 	if (!chip || !chip->irq_set_affinity)
171 		return -EINVAL;
172 
173 	if (irq_can_move_pcntxt(data)) {
174 		ret = irq_do_set_affinity(data, mask, false);
175 	} else {
176 		irqd_set_move_pending(data);
177 		irq_copy_pending(desc, mask);
178 	}
179 
180 	if (desc->affinity_notify) {
181 		kref_get(&desc->affinity_notify->kref);
182 		schedule_work(&desc->affinity_notify->work);
183 	}
184 	irqd_set(data, IRQD_AFFINITY_SET);
185 
186 	return ret;
187 }
188 
189 /**
190  *	irq_set_affinity - Set the irq affinity of a given irq
191  *	@irq:		Interrupt to set affinity
192  *	@mask:		cpumask
193  *
194  */
195 int irq_set_affinity(unsigned int irq, const struct cpumask *mask)
196 {
197 	struct irq_desc *desc = irq_to_desc(irq);
198 	unsigned long flags;
199 	int ret;
200 
201 	if (!desc)
202 		return -EINVAL;
203 
204 	raw_spin_lock_irqsave(&desc->lock, flags);
205 	ret =  __irq_set_affinity_locked(irq_desc_get_irq_data(desc), mask);
206 	raw_spin_unlock_irqrestore(&desc->lock, flags);
207 	return ret;
208 }
209 
210 int irq_set_affinity_hint(unsigned int irq, const struct cpumask *m)
211 {
212 	unsigned long flags;
213 	struct irq_desc *desc = irq_get_desc_lock(irq, &flags, IRQ_GET_DESC_CHECK_GLOBAL);
214 
215 	if (!desc)
216 		return -EINVAL;
217 	desc->affinity_hint = m;
218 	irq_put_desc_unlock(desc, flags);
219 	return 0;
220 }
221 EXPORT_SYMBOL_GPL(irq_set_affinity_hint);
222 
223 static void irq_affinity_notify(struct work_struct *work)
224 {
225 	struct irq_affinity_notify *notify =
226 		container_of(work, struct irq_affinity_notify, work);
227 	struct irq_desc *desc = irq_to_desc(notify->irq);
228 	cpumask_var_t cpumask;
229 	unsigned long flags;
230 
231 	if (!desc || !alloc_cpumask_var(&cpumask, GFP_KERNEL))
232 		goto out;
233 
234 	raw_spin_lock_irqsave(&desc->lock, flags);
235 	if (irq_move_pending(&desc->irq_data))
236 		irq_get_pending(cpumask, desc);
237 	else
238 		cpumask_copy(cpumask, desc->irq_data.affinity);
239 	raw_spin_unlock_irqrestore(&desc->lock, flags);
240 
241 	notify->notify(notify, cpumask);
242 
243 	free_cpumask_var(cpumask);
244 out:
245 	kref_put(&notify->kref, notify->release);
246 }
247 
248 /**
249  *	irq_set_affinity_notifier - control notification of IRQ affinity changes
250  *	@irq:		Interrupt for which to enable/disable notification
251  *	@notify:	Context for notification, or %NULL to disable
252  *			notification.  Function pointers must be initialised;
253  *			the other fields will be initialised by this function.
254  *
255  *	Must be called in process context.  Notification may only be enabled
256  *	after the IRQ is allocated and must be disabled before the IRQ is
257  *	freed using free_irq().
258  */
259 int
260 irq_set_affinity_notifier(unsigned int irq, struct irq_affinity_notify *notify)
261 {
262 	struct irq_desc *desc = irq_to_desc(irq);
263 	struct irq_affinity_notify *old_notify;
264 	unsigned long flags;
265 
266 	/* The release function is promised process context */
267 	might_sleep();
268 
269 	if (!desc)
270 		return -EINVAL;
271 
272 	/* Complete initialisation of *notify */
273 	if (notify) {
274 		notify->irq = irq;
275 		kref_init(&notify->kref);
276 		INIT_WORK(&notify->work, irq_affinity_notify);
277 	}
278 
279 	raw_spin_lock_irqsave(&desc->lock, flags);
280 	old_notify = desc->affinity_notify;
281 	desc->affinity_notify = notify;
282 	raw_spin_unlock_irqrestore(&desc->lock, flags);
283 
284 	if (old_notify)
285 		kref_put(&old_notify->kref, old_notify->release);
286 
287 	return 0;
288 }
289 EXPORT_SYMBOL_GPL(irq_set_affinity_notifier);
290 
291 #ifndef CONFIG_AUTO_IRQ_AFFINITY
292 /*
293  * Generic version of the affinity autoselector.
294  */
295 static int
296 setup_affinity(unsigned int irq, struct irq_desc *desc, struct cpumask *mask)
297 {
298 	struct cpumask *set = irq_default_affinity;
299 	int node = desc->irq_data.node;
300 
301 	/* Excludes PER_CPU and NO_BALANCE interrupts */
302 	if (!irq_can_set_affinity(irq))
303 		return 0;
304 
305 	/*
306 	 * Preserve an userspace affinity setup, but make sure that
307 	 * one of the targets is online.
308 	 */
309 	if (irqd_has_set(&desc->irq_data, IRQD_AFFINITY_SET)) {
310 		if (cpumask_intersects(desc->irq_data.affinity,
311 				       cpu_online_mask))
312 			set = desc->irq_data.affinity;
313 		else
314 			irqd_clear(&desc->irq_data, IRQD_AFFINITY_SET);
315 	}
316 
317 	cpumask_and(mask, cpu_online_mask, set);
318 	if (node != NUMA_NO_NODE) {
319 		const struct cpumask *nodemask = cpumask_of_node(node);
320 
321 		/* make sure at least one of the cpus in nodemask is online */
322 		if (cpumask_intersects(mask, nodemask))
323 			cpumask_and(mask, mask, nodemask);
324 	}
325 	irq_do_set_affinity(&desc->irq_data, mask, false);
326 	return 0;
327 }
328 #else
329 static inline int
330 setup_affinity(unsigned int irq, struct irq_desc *d, struct cpumask *mask)
331 {
332 	return irq_select_affinity(irq);
333 }
334 #endif
335 
336 /*
337  * Called when affinity is set via /proc/irq
338  */
339 int irq_select_affinity_usr(unsigned int irq, struct cpumask *mask)
340 {
341 	struct irq_desc *desc = irq_to_desc(irq);
342 	unsigned long flags;
343 	int ret;
344 
345 	raw_spin_lock_irqsave(&desc->lock, flags);
346 	ret = setup_affinity(irq, desc, mask);
347 	raw_spin_unlock_irqrestore(&desc->lock, flags);
348 	return ret;
349 }
350 
351 #else
352 static inline int
353 setup_affinity(unsigned int irq, struct irq_desc *desc, struct cpumask *mask)
354 {
355 	return 0;
356 }
357 #endif
358 
359 void __disable_irq(struct irq_desc *desc, unsigned int irq, bool suspend)
360 {
361 	if (suspend) {
362 		if (!desc->action || (desc->action->flags & IRQF_NO_SUSPEND))
363 			return;
364 		desc->istate |= IRQS_SUSPENDED;
365 	}
366 
367 	if (!desc->depth++)
368 		irq_disable(desc);
369 }
370 
371 static int __disable_irq_nosync(unsigned int irq)
372 {
373 	unsigned long flags;
374 	struct irq_desc *desc = irq_get_desc_buslock(irq, &flags, IRQ_GET_DESC_CHECK_GLOBAL);
375 
376 	if (!desc)
377 		return -EINVAL;
378 	__disable_irq(desc, irq, false);
379 	irq_put_desc_busunlock(desc, flags);
380 	return 0;
381 }
382 
383 /**
384  *	disable_irq_nosync - disable an irq without waiting
385  *	@irq: Interrupt to disable
386  *
387  *	Disable the selected interrupt line.  Disables and Enables are
388  *	nested.
389  *	Unlike disable_irq(), this function does not ensure existing
390  *	instances of the IRQ handler have completed before returning.
391  *
392  *	This function may be called from IRQ context.
393  */
394 void disable_irq_nosync(unsigned int irq)
395 {
396 	__disable_irq_nosync(irq);
397 }
398 EXPORT_SYMBOL(disable_irq_nosync);
399 
400 /**
401  *	disable_irq - disable an irq and wait for completion
402  *	@irq: Interrupt to disable
403  *
404  *	Disable the selected interrupt line.  Enables and Disables are
405  *	nested.
406  *	This function waits for any pending IRQ handlers for this interrupt
407  *	to complete before returning. If you use this function while
408  *	holding a resource the IRQ handler may need you will deadlock.
409  *
410  *	This function may be called - with care - from IRQ context.
411  */
412 void disable_irq(unsigned int irq)
413 {
414 	if (!__disable_irq_nosync(irq))
415 		synchronize_irq(irq);
416 }
417 EXPORT_SYMBOL(disable_irq);
418 
419 void __enable_irq(struct irq_desc *desc, unsigned int irq, bool resume)
420 {
421 	if (resume) {
422 		if (!(desc->istate & IRQS_SUSPENDED)) {
423 			if (!desc->action)
424 				return;
425 			if (!(desc->action->flags & IRQF_FORCE_RESUME))
426 				return;
427 			/* Pretend that it got disabled ! */
428 			desc->depth++;
429 		}
430 		desc->istate &= ~IRQS_SUSPENDED;
431 	}
432 
433 	switch (desc->depth) {
434 	case 0:
435  err_out:
436 		WARN(1, KERN_WARNING "Unbalanced enable for IRQ %d\n", irq);
437 		break;
438 	case 1: {
439 		if (desc->istate & IRQS_SUSPENDED)
440 			goto err_out;
441 		/* Prevent probing on this irq: */
442 		irq_settings_set_noprobe(desc);
443 		irq_enable(desc);
444 		check_irq_resend(desc, irq);
445 		/* fall-through */
446 	}
447 	default:
448 		desc->depth--;
449 	}
450 }
451 
452 /**
453  *	enable_irq - enable handling of an irq
454  *	@irq: Interrupt to enable
455  *
456  *	Undoes the effect of one call to disable_irq().  If this
457  *	matches the last disable, processing of interrupts on this
458  *	IRQ line is re-enabled.
459  *
460  *	This function may be called from IRQ context only when
461  *	desc->irq_data.chip->bus_lock and desc->chip->bus_sync_unlock are NULL !
462  */
463 void enable_irq(unsigned int irq)
464 {
465 	unsigned long flags;
466 	struct irq_desc *desc = irq_get_desc_buslock(irq, &flags, IRQ_GET_DESC_CHECK_GLOBAL);
467 
468 	if (!desc)
469 		return;
470 	if (WARN(!desc->irq_data.chip,
471 		 KERN_ERR "enable_irq before setup/request_irq: irq %u\n", irq))
472 		goto out;
473 
474 	__enable_irq(desc, irq, false);
475 out:
476 	irq_put_desc_busunlock(desc, flags);
477 }
478 EXPORT_SYMBOL(enable_irq);
479 
480 static int set_irq_wake_real(unsigned int irq, unsigned int on)
481 {
482 	struct irq_desc *desc = irq_to_desc(irq);
483 	int ret = -ENXIO;
484 
485 	if (irq_desc_get_chip(desc)->flags &  IRQCHIP_SKIP_SET_WAKE)
486 		return 0;
487 
488 	if (desc->irq_data.chip->irq_set_wake)
489 		ret = desc->irq_data.chip->irq_set_wake(&desc->irq_data, on);
490 
491 	return ret;
492 }
493 
494 /**
495  *	irq_set_irq_wake - control irq power management wakeup
496  *	@irq:	interrupt to control
497  *	@on:	enable/disable power management wakeup
498  *
499  *	Enable/disable power management wakeup mode, which is
500  *	disabled by default.  Enables and disables must match,
501  *	just as they match for non-wakeup mode support.
502  *
503  *	Wakeup mode lets this IRQ wake the system from sleep
504  *	states like "suspend to RAM".
505  */
506 int irq_set_irq_wake(unsigned int irq, unsigned int on)
507 {
508 	unsigned long flags;
509 	struct irq_desc *desc = irq_get_desc_buslock(irq, &flags, IRQ_GET_DESC_CHECK_GLOBAL);
510 	int ret = 0;
511 
512 	if (!desc)
513 		return -EINVAL;
514 
515 	/* wakeup-capable irqs can be shared between drivers that
516 	 * don't need to have the same sleep mode behaviors.
517 	 */
518 	if (on) {
519 		if (desc->wake_depth++ == 0) {
520 			ret = set_irq_wake_real(irq, on);
521 			if (ret)
522 				desc->wake_depth = 0;
523 			else
524 				irqd_set(&desc->irq_data, IRQD_WAKEUP_STATE);
525 		}
526 	} else {
527 		if (desc->wake_depth == 0) {
528 			WARN(1, "Unbalanced IRQ %d wake disable\n", irq);
529 		} else if (--desc->wake_depth == 0) {
530 			ret = set_irq_wake_real(irq, on);
531 			if (ret)
532 				desc->wake_depth = 1;
533 			else
534 				irqd_clear(&desc->irq_data, IRQD_WAKEUP_STATE);
535 		}
536 	}
537 	irq_put_desc_busunlock(desc, flags);
538 	return ret;
539 }
540 EXPORT_SYMBOL(irq_set_irq_wake);
541 
542 /*
543  * Internal function that tells the architecture code whether a
544  * particular irq has been exclusively allocated or is available
545  * for driver use.
546  */
547 int can_request_irq(unsigned int irq, unsigned long irqflags)
548 {
549 	unsigned long flags;
550 	struct irq_desc *desc = irq_get_desc_lock(irq, &flags, 0);
551 	int canrequest = 0;
552 
553 	if (!desc)
554 		return 0;
555 
556 	if (irq_settings_can_request(desc)) {
557 		if (desc->action)
558 			if (irqflags & desc->action->flags & IRQF_SHARED)
559 				canrequest =1;
560 	}
561 	irq_put_desc_unlock(desc, flags);
562 	return canrequest;
563 }
564 
565 int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
566 		      unsigned long flags)
567 {
568 	struct irq_chip *chip = desc->irq_data.chip;
569 	int ret, unmask = 0;
570 
571 	if (!chip || !chip->irq_set_type) {
572 		/*
573 		 * IRQF_TRIGGER_* but the PIC does not support multiple
574 		 * flow-types?
575 		 */
576 		pr_debug("No set_type function for IRQ %d (%s)\n", irq,
577 			 chip ? (chip->name ? : "unknown") : "unknown");
578 		return 0;
579 	}
580 
581 	flags &= IRQ_TYPE_SENSE_MASK;
582 
583 	if (chip->flags & IRQCHIP_SET_TYPE_MASKED) {
584 		if (!irqd_irq_masked(&desc->irq_data))
585 			mask_irq(desc);
586 		if (!irqd_irq_disabled(&desc->irq_data))
587 			unmask = 1;
588 	}
589 
590 	/* caller masked out all except trigger mode flags */
591 	ret = chip->irq_set_type(&desc->irq_data, flags);
592 
593 	switch (ret) {
594 	case IRQ_SET_MASK_OK:
595 		irqd_clear(&desc->irq_data, IRQD_TRIGGER_MASK);
596 		irqd_set(&desc->irq_data, flags);
597 
598 	case IRQ_SET_MASK_OK_NOCOPY:
599 		flags = irqd_get_trigger_type(&desc->irq_data);
600 		irq_settings_set_trigger_mask(desc, flags);
601 		irqd_clear(&desc->irq_data, IRQD_LEVEL);
602 		irq_settings_clr_level(desc);
603 		if (flags & IRQ_TYPE_LEVEL_MASK) {
604 			irq_settings_set_level(desc);
605 			irqd_set(&desc->irq_data, IRQD_LEVEL);
606 		}
607 
608 		ret = 0;
609 		break;
610 	default:
611 		pr_err("Setting trigger mode %lu for irq %u failed (%pF)\n",
612 		       flags, irq, chip->irq_set_type);
613 	}
614 	if (unmask)
615 		unmask_irq(desc);
616 	return ret;
617 }
618 
619 #ifdef CONFIG_HARDIRQS_SW_RESEND
620 int irq_set_parent(int irq, int parent_irq)
621 {
622 	unsigned long flags;
623 	struct irq_desc *desc = irq_get_desc_lock(irq, &flags, 0);
624 
625 	if (!desc)
626 		return -EINVAL;
627 
628 	desc->parent_irq = parent_irq;
629 
630 	irq_put_desc_unlock(desc, flags);
631 	return 0;
632 }
633 #endif
634 
635 /*
636  * Default primary interrupt handler for threaded interrupts. Is
637  * assigned as primary handler when request_threaded_irq is called
638  * with handler == NULL. Useful for oneshot interrupts.
639  */
640 static irqreturn_t irq_default_primary_handler(int irq, void *dev_id)
641 {
642 	return IRQ_WAKE_THREAD;
643 }
644 
645 /*
646  * Primary handler for nested threaded interrupts. Should never be
647  * called.
648  */
649 static irqreturn_t irq_nested_primary_handler(int irq, void *dev_id)
650 {
651 	WARN(1, "Primary handler called for nested irq %d\n", irq);
652 	return IRQ_NONE;
653 }
654 
655 static int irq_wait_for_interrupt(struct irqaction *action)
656 {
657 	set_current_state(TASK_INTERRUPTIBLE);
658 
659 	while (!kthread_should_stop()) {
660 
661 		if (test_and_clear_bit(IRQTF_RUNTHREAD,
662 				       &action->thread_flags)) {
663 			__set_current_state(TASK_RUNNING);
664 			return 0;
665 		}
666 		schedule();
667 		set_current_state(TASK_INTERRUPTIBLE);
668 	}
669 	__set_current_state(TASK_RUNNING);
670 	return -1;
671 }
672 
673 /*
674  * Oneshot interrupts keep the irq line masked until the threaded
675  * handler finished. unmask if the interrupt has not been disabled and
676  * is marked MASKED.
677  */
678 static void irq_finalize_oneshot(struct irq_desc *desc,
679 				 struct irqaction *action)
680 {
681 	if (!(desc->istate & IRQS_ONESHOT))
682 		return;
683 again:
684 	chip_bus_lock(desc);
685 	raw_spin_lock_irq(&desc->lock);
686 
687 	/*
688 	 * Implausible though it may be we need to protect us against
689 	 * the following scenario:
690 	 *
691 	 * The thread is faster done than the hard interrupt handler
692 	 * on the other CPU. If we unmask the irq line then the
693 	 * interrupt can come in again and masks the line, leaves due
694 	 * to IRQS_INPROGRESS and the irq line is masked forever.
695 	 *
696 	 * This also serializes the state of shared oneshot handlers
697 	 * versus "desc->threads_onehsot |= action->thread_mask;" in
698 	 * irq_wake_thread(). See the comment there which explains the
699 	 * serialization.
700 	 */
701 	if (unlikely(irqd_irq_inprogress(&desc->irq_data))) {
702 		raw_spin_unlock_irq(&desc->lock);
703 		chip_bus_sync_unlock(desc);
704 		cpu_relax();
705 		goto again;
706 	}
707 
708 	/*
709 	 * Now check again, whether the thread should run. Otherwise
710 	 * we would clear the threads_oneshot bit of this thread which
711 	 * was just set.
712 	 */
713 	if (test_bit(IRQTF_RUNTHREAD, &action->thread_flags))
714 		goto out_unlock;
715 
716 	desc->threads_oneshot &= ~action->thread_mask;
717 
718 	if (!desc->threads_oneshot && !irqd_irq_disabled(&desc->irq_data) &&
719 	    irqd_irq_masked(&desc->irq_data))
720 		unmask_irq(desc);
721 
722 out_unlock:
723 	raw_spin_unlock_irq(&desc->lock);
724 	chip_bus_sync_unlock(desc);
725 }
726 
727 #ifdef CONFIG_SMP
728 /*
729  * Check whether we need to chasnge the affinity of the interrupt thread.
730  */
731 static void
732 irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action)
733 {
734 	cpumask_var_t mask;
735 	bool valid = true;
736 
737 	if (!test_and_clear_bit(IRQTF_AFFINITY, &action->thread_flags))
738 		return;
739 
740 	/*
741 	 * In case we are out of memory we set IRQTF_AFFINITY again and
742 	 * try again next time
743 	 */
744 	if (!alloc_cpumask_var(&mask, GFP_KERNEL)) {
745 		set_bit(IRQTF_AFFINITY, &action->thread_flags);
746 		return;
747 	}
748 
749 	raw_spin_lock_irq(&desc->lock);
750 	/*
751 	 * This code is triggered unconditionally. Check the affinity
752 	 * mask pointer. For CPU_MASK_OFFSTACK=n this is optimized out.
753 	 */
754 	if (desc->irq_data.affinity)
755 		cpumask_copy(mask, desc->irq_data.affinity);
756 	else
757 		valid = false;
758 	raw_spin_unlock_irq(&desc->lock);
759 
760 	if (valid)
761 		set_cpus_allowed_ptr(current, mask);
762 	free_cpumask_var(mask);
763 }
764 #else
765 static inline void
766 irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action) { }
767 #endif
768 
769 /*
770  * Interrupts which are not explicitely requested as threaded
771  * interrupts rely on the implicit bh/preempt disable of the hard irq
772  * context. So we need to disable bh here to avoid deadlocks and other
773  * side effects.
774  */
775 static irqreturn_t
776 irq_forced_thread_fn(struct irq_desc *desc, struct irqaction *action)
777 {
778 	irqreturn_t ret;
779 
780 	local_bh_disable();
781 	ret = action->thread_fn(action->irq, action->dev_id);
782 	irq_finalize_oneshot(desc, action);
783 	local_bh_enable();
784 	return ret;
785 }
786 
787 /*
788  * Interrupts explicitely requested as threaded interupts want to be
789  * preemtible - many of them need to sleep and wait for slow busses to
790  * complete.
791  */
792 static irqreturn_t irq_thread_fn(struct irq_desc *desc,
793 		struct irqaction *action)
794 {
795 	irqreturn_t ret;
796 
797 	ret = action->thread_fn(action->irq, action->dev_id);
798 	irq_finalize_oneshot(desc, action);
799 	return ret;
800 }
801 
802 static void wake_threads_waitq(struct irq_desc *desc)
803 {
804 	if (atomic_dec_and_test(&desc->threads_active) &&
805 	    waitqueue_active(&desc->wait_for_threads))
806 		wake_up(&desc->wait_for_threads);
807 }
808 
809 static void irq_thread_dtor(struct callback_head *unused)
810 {
811 	struct task_struct *tsk = current;
812 	struct irq_desc *desc;
813 	struct irqaction *action;
814 
815 	if (WARN_ON_ONCE(!(current->flags & PF_EXITING)))
816 		return;
817 
818 	action = kthread_data(tsk);
819 
820 	pr_err("exiting task \"%s\" (%d) is an active IRQ thread (irq %d)\n",
821 	       tsk->comm, tsk->pid, action->irq);
822 
823 
824 	desc = irq_to_desc(action->irq);
825 	/*
826 	 * If IRQTF_RUNTHREAD is set, we need to decrement
827 	 * desc->threads_active and wake possible waiters.
828 	 */
829 	if (test_and_clear_bit(IRQTF_RUNTHREAD, &action->thread_flags))
830 		wake_threads_waitq(desc);
831 
832 	/* Prevent a stale desc->threads_oneshot */
833 	irq_finalize_oneshot(desc, action);
834 }
835 
836 /*
837  * Interrupt handler thread
838  */
839 static int irq_thread(void *data)
840 {
841 	struct callback_head on_exit_work;
842 	static const struct sched_param param = {
843 		.sched_priority = MAX_USER_RT_PRIO/2,
844 	};
845 	struct irqaction *action = data;
846 	struct irq_desc *desc = irq_to_desc(action->irq);
847 	irqreturn_t (*handler_fn)(struct irq_desc *desc,
848 			struct irqaction *action);
849 
850 	if (force_irqthreads && test_bit(IRQTF_FORCED_THREAD,
851 					&action->thread_flags))
852 		handler_fn = irq_forced_thread_fn;
853 	else
854 		handler_fn = irq_thread_fn;
855 
856 	sched_setscheduler(current, SCHED_FIFO, &param);
857 
858 	init_task_work(&on_exit_work, irq_thread_dtor);
859 	task_work_add(current, &on_exit_work, false);
860 
861 	irq_thread_check_affinity(desc, action);
862 
863 	while (!irq_wait_for_interrupt(action)) {
864 		irqreturn_t action_ret;
865 
866 		irq_thread_check_affinity(desc, action);
867 
868 		action_ret = handler_fn(desc, action);
869 		if (!noirqdebug)
870 			note_interrupt(action->irq, desc, action_ret);
871 
872 		wake_threads_waitq(desc);
873 	}
874 
875 	/*
876 	 * This is the regular exit path. __free_irq() is stopping the
877 	 * thread via kthread_stop() after calling
878 	 * synchronize_irq(). So neither IRQTF_RUNTHREAD nor the
879 	 * oneshot mask bit can be set. We cannot verify that as we
880 	 * cannot touch the oneshot mask at this point anymore as
881 	 * __setup_irq() might have given out currents thread_mask
882 	 * again.
883 	 */
884 	task_work_cancel(current, irq_thread_dtor);
885 	return 0;
886 }
887 
888 static void irq_setup_forced_threading(struct irqaction *new)
889 {
890 	if (!force_irqthreads)
891 		return;
892 	if (new->flags & (IRQF_NO_THREAD | IRQF_PERCPU | IRQF_ONESHOT))
893 		return;
894 
895 	new->flags |= IRQF_ONESHOT;
896 
897 	if (!new->thread_fn) {
898 		set_bit(IRQTF_FORCED_THREAD, &new->thread_flags);
899 		new->thread_fn = new->handler;
900 		new->handler = irq_default_primary_handler;
901 	}
902 }
903 
904 /*
905  * Internal function to register an irqaction - typically used to
906  * allocate special interrupts that are part of the architecture.
907  */
908 static int
909 __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
910 {
911 	struct irqaction *old, **old_ptr;
912 	unsigned long flags, thread_mask = 0;
913 	int ret, nested, shared = 0;
914 	cpumask_var_t mask;
915 
916 	if (!desc)
917 		return -EINVAL;
918 
919 	if (desc->irq_data.chip == &no_irq_chip)
920 		return -ENOSYS;
921 	if (!try_module_get(desc->owner))
922 		return -ENODEV;
923 
924 	/*
925 	 * Check whether the interrupt nests into another interrupt
926 	 * thread.
927 	 */
928 	nested = irq_settings_is_nested_thread(desc);
929 	if (nested) {
930 		if (!new->thread_fn) {
931 			ret = -EINVAL;
932 			goto out_mput;
933 		}
934 		/*
935 		 * Replace the primary handler which was provided from
936 		 * the driver for non nested interrupt handling by the
937 		 * dummy function which warns when called.
938 		 */
939 		new->handler = irq_nested_primary_handler;
940 	} else {
941 		if (irq_settings_can_thread(desc))
942 			irq_setup_forced_threading(new);
943 	}
944 
945 	/*
946 	 * Create a handler thread when a thread function is supplied
947 	 * and the interrupt does not nest into another interrupt
948 	 * thread.
949 	 */
950 	if (new->thread_fn && !nested) {
951 		struct task_struct *t;
952 
953 		t = kthread_create(irq_thread, new, "irq/%d-%s", irq,
954 				   new->name);
955 		if (IS_ERR(t)) {
956 			ret = PTR_ERR(t);
957 			goto out_mput;
958 		}
959 		/*
960 		 * We keep the reference to the task struct even if
961 		 * the thread dies to avoid that the interrupt code
962 		 * references an already freed task_struct.
963 		 */
964 		get_task_struct(t);
965 		new->thread = t;
966 		/*
967 		 * Tell the thread to set its affinity. This is
968 		 * important for shared interrupt handlers as we do
969 		 * not invoke setup_affinity() for the secondary
970 		 * handlers as everything is already set up. Even for
971 		 * interrupts marked with IRQF_NO_BALANCE this is
972 		 * correct as we want the thread to move to the cpu(s)
973 		 * on which the requesting code placed the interrupt.
974 		 */
975 		set_bit(IRQTF_AFFINITY, &new->thread_flags);
976 	}
977 
978 	if (!alloc_cpumask_var(&mask, GFP_KERNEL)) {
979 		ret = -ENOMEM;
980 		goto out_thread;
981 	}
982 
983 	/*
984 	 * Drivers are often written to work w/o knowledge about the
985 	 * underlying irq chip implementation, so a request for a
986 	 * threaded irq without a primary hard irq context handler
987 	 * requires the ONESHOT flag to be set. Some irq chips like
988 	 * MSI based interrupts are per se one shot safe. Check the
989 	 * chip flags, so we can avoid the unmask dance at the end of
990 	 * the threaded handler for those.
991 	 */
992 	if (desc->irq_data.chip->flags & IRQCHIP_ONESHOT_SAFE)
993 		new->flags &= ~IRQF_ONESHOT;
994 
995 	/*
996 	 * The following block of code has to be executed atomically
997 	 */
998 	raw_spin_lock_irqsave(&desc->lock, flags);
999 	old_ptr = &desc->action;
1000 	old = *old_ptr;
1001 	if (old) {
1002 		/*
1003 		 * Can't share interrupts unless both agree to and are
1004 		 * the same type (level, edge, polarity). So both flag
1005 		 * fields must have IRQF_SHARED set and the bits which
1006 		 * set the trigger type must match. Also all must
1007 		 * agree on ONESHOT.
1008 		 */
1009 		if (!((old->flags & new->flags) & IRQF_SHARED) ||
1010 		    ((old->flags ^ new->flags) & IRQF_TRIGGER_MASK) ||
1011 		    ((old->flags ^ new->flags) & IRQF_ONESHOT))
1012 			goto mismatch;
1013 
1014 		/* All handlers must agree on per-cpuness */
1015 		if ((old->flags & IRQF_PERCPU) !=
1016 		    (new->flags & IRQF_PERCPU))
1017 			goto mismatch;
1018 
1019 		/* add new interrupt at end of irq queue */
1020 		do {
1021 			/*
1022 			 * Or all existing action->thread_mask bits,
1023 			 * so we can find the next zero bit for this
1024 			 * new action.
1025 			 */
1026 			thread_mask |= old->thread_mask;
1027 			old_ptr = &old->next;
1028 			old = *old_ptr;
1029 		} while (old);
1030 		shared = 1;
1031 	}
1032 
1033 	/*
1034 	 * Setup the thread mask for this irqaction for ONESHOT. For
1035 	 * !ONESHOT irqs the thread mask is 0 so we can avoid a
1036 	 * conditional in irq_wake_thread().
1037 	 */
1038 	if (new->flags & IRQF_ONESHOT) {
1039 		/*
1040 		 * Unlikely to have 32 resp 64 irqs sharing one line,
1041 		 * but who knows.
1042 		 */
1043 		if (thread_mask == ~0UL) {
1044 			ret = -EBUSY;
1045 			goto out_mask;
1046 		}
1047 		/*
1048 		 * The thread_mask for the action is or'ed to
1049 		 * desc->thread_active to indicate that the
1050 		 * IRQF_ONESHOT thread handler has been woken, but not
1051 		 * yet finished. The bit is cleared when a thread
1052 		 * completes. When all threads of a shared interrupt
1053 		 * line have completed desc->threads_active becomes
1054 		 * zero and the interrupt line is unmasked. See
1055 		 * handle.c:irq_wake_thread() for further information.
1056 		 *
1057 		 * If no thread is woken by primary (hard irq context)
1058 		 * interrupt handlers, then desc->threads_active is
1059 		 * also checked for zero to unmask the irq line in the
1060 		 * affected hard irq flow handlers
1061 		 * (handle_[fasteoi|level]_irq).
1062 		 *
1063 		 * The new action gets the first zero bit of
1064 		 * thread_mask assigned. See the loop above which or's
1065 		 * all existing action->thread_mask bits.
1066 		 */
1067 		new->thread_mask = 1 << ffz(thread_mask);
1068 
1069 	} else if (new->handler == irq_default_primary_handler &&
1070 		   !(desc->irq_data.chip->flags & IRQCHIP_ONESHOT_SAFE)) {
1071 		/*
1072 		 * The interrupt was requested with handler = NULL, so
1073 		 * we use the default primary handler for it. But it
1074 		 * does not have the oneshot flag set. In combination
1075 		 * with level interrupts this is deadly, because the
1076 		 * default primary handler just wakes the thread, then
1077 		 * the irq lines is reenabled, but the device still
1078 		 * has the level irq asserted. Rinse and repeat....
1079 		 *
1080 		 * While this works for edge type interrupts, we play
1081 		 * it safe and reject unconditionally because we can't
1082 		 * say for sure which type this interrupt really
1083 		 * has. The type flags are unreliable as the
1084 		 * underlying chip implementation can override them.
1085 		 */
1086 		pr_err("Threaded irq requested with handler=NULL and !ONESHOT for irq %d\n",
1087 		       irq);
1088 		ret = -EINVAL;
1089 		goto out_mask;
1090 	}
1091 
1092 	if (!shared) {
1093 		init_waitqueue_head(&desc->wait_for_threads);
1094 
1095 		/* Setup the type (level, edge polarity) if configured: */
1096 		if (new->flags & IRQF_TRIGGER_MASK) {
1097 			ret = __irq_set_trigger(desc, irq,
1098 					new->flags & IRQF_TRIGGER_MASK);
1099 
1100 			if (ret)
1101 				goto out_mask;
1102 		}
1103 
1104 		desc->istate &= ~(IRQS_AUTODETECT | IRQS_SPURIOUS_DISABLED | \
1105 				  IRQS_ONESHOT | IRQS_WAITING);
1106 		irqd_clear(&desc->irq_data, IRQD_IRQ_INPROGRESS);
1107 
1108 		if (new->flags & IRQF_PERCPU) {
1109 			irqd_set(&desc->irq_data, IRQD_PER_CPU);
1110 			irq_settings_set_per_cpu(desc);
1111 		}
1112 
1113 		if (new->flags & IRQF_ONESHOT)
1114 			desc->istate |= IRQS_ONESHOT;
1115 
1116 		if (irq_settings_can_autoenable(desc))
1117 			irq_startup(desc, true);
1118 		else
1119 			/* Undo nested disables: */
1120 			desc->depth = 1;
1121 
1122 		/* Exclude IRQ from balancing if requested */
1123 		if (new->flags & IRQF_NOBALANCING) {
1124 			irq_settings_set_no_balancing(desc);
1125 			irqd_set(&desc->irq_data, IRQD_NO_BALANCING);
1126 		}
1127 
1128 		/* Set default affinity mask once everything is setup */
1129 		setup_affinity(irq, desc, mask);
1130 
1131 	} else if (new->flags & IRQF_TRIGGER_MASK) {
1132 		unsigned int nmsk = new->flags & IRQF_TRIGGER_MASK;
1133 		unsigned int omsk = irq_settings_get_trigger_mask(desc);
1134 
1135 		if (nmsk != omsk)
1136 			/* hope the handler works with current  trigger mode */
1137 			pr_warning("irq %d uses trigger mode %u; requested %u\n",
1138 				   irq, nmsk, omsk);
1139 	}
1140 
1141 	new->irq = irq;
1142 	*old_ptr = new;
1143 
1144 	/* Reset broken irq detection when installing new handler */
1145 	desc->irq_count = 0;
1146 	desc->irqs_unhandled = 0;
1147 
1148 	/*
1149 	 * Check whether we disabled the irq via the spurious handler
1150 	 * before. Reenable it and give it another chance.
1151 	 */
1152 	if (shared && (desc->istate & IRQS_SPURIOUS_DISABLED)) {
1153 		desc->istate &= ~IRQS_SPURIOUS_DISABLED;
1154 		__enable_irq(desc, irq, false);
1155 	}
1156 
1157 	raw_spin_unlock_irqrestore(&desc->lock, flags);
1158 
1159 	/*
1160 	 * Strictly no need to wake it up, but hung_task complains
1161 	 * when no hard interrupt wakes the thread up.
1162 	 */
1163 	if (new->thread)
1164 		wake_up_process(new->thread);
1165 
1166 	register_irq_proc(irq, desc);
1167 	new->dir = NULL;
1168 	register_handler_proc(irq, new);
1169 	free_cpumask_var(mask);
1170 
1171 	return 0;
1172 
1173 mismatch:
1174 	if (!(new->flags & IRQF_PROBE_SHARED)) {
1175 		pr_err("Flags mismatch irq %d. %08x (%s) vs. %08x (%s)\n",
1176 		       irq, new->flags, new->name, old->flags, old->name);
1177 #ifdef CONFIG_DEBUG_SHIRQ
1178 		dump_stack();
1179 #endif
1180 	}
1181 	ret = -EBUSY;
1182 
1183 out_mask:
1184 	raw_spin_unlock_irqrestore(&desc->lock, flags);
1185 	free_cpumask_var(mask);
1186 
1187 out_thread:
1188 	if (new->thread) {
1189 		struct task_struct *t = new->thread;
1190 
1191 		new->thread = NULL;
1192 		kthread_stop(t);
1193 		put_task_struct(t);
1194 	}
1195 out_mput:
1196 	module_put(desc->owner);
1197 	return ret;
1198 }
1199 
1200 /**
1201  *	setup_irq - setup an interrupt
1202  *	@irq: Interrupt line to setup
1203  *	@act: irqaction for the interrupt
1204  *
1205  * Used to statically setup interrupts in the early boot process.
1206  */
1207 int setup_irq(unsigned int irq, struct irqaction *act)
1208 {
1209 	int retval;
1210 	struct irq_desc *desc = irq_to_desc(irq);
1211 
1212 	if (WARN_ON(irq_settings_is_per_cpu_devid(desc)))
1213 		return -EINVAL;
1214 	chip_bus_lock(desc);
1215 	retval = __setup_irq(irq, desc, act);
1216 	chip_bus_sync_unlock(desc);
1217 
1218 	return retval;
1219 }
1220 EXPORT_SYMBOL_GPL(setup_irq);
1221 
1222 /*
1223  * Internal function to unregister an irqaction - used to free
1224  * regular and special interrupts that are part of the architecture.
1225  */
1226 static struct irqaction *__free_irq(unsigned int irq, void *dev_id)
1227 {
1228 	struct irq_desc *desc = irq_to_desc(irq);
1229 	struct irqaction *action, **action_ptr;
1230 	unsigned long flags;
1231 
1232 	WARN(in_interrupt(), "Trying to free IRQ %d from IRQ context!\n", irq);
1233 
1234 	if (!desc)
1235 		return NULL;
1236 
1237 	raw_spin_lock_irqsave(&desc->lock, flags);
1238 
1239 	/*
1240 	 * There can be multiple actions per IRQ descriptor, find the right
1241 	 * one based on the dev_id:
1242 	 */
1243 	action_ptr = &desc->action;
1244 	for (;;) {
1245 		action = *action_ptr;
1246 
1247 		if (!action) {
1248 			WARN(1, "Trying to free already-free IRQ %d\n", irq);
1249 			raw_spin_unlock_irqrestore(&desc->lock, flags);
1250 
1251 			return NULL;
1252 		}
1253 
1254 		if (action->dev_id == dev_id)
1255 			break;
1256 		action_ptr = &action->next;
1257 	}
1258 
1259 	/* Found it - now remove it from the list of entries: */
1260 	*action_ptr = action->next;
1261 
1262 	/* If this was the last handler, shut down the IRQ line: */
1263 	if (!desc->action)
1264 		irq_shutdown(desc);
1265 
1266 #ifdef CONFIG_SMP
1267 	/* make sure affinity_hint is cleaned up */
1268 	if (WARN_ON_ONCE(desc->affinity_hint))
1269 		desc->affinity_hint = NULL;
1270 #endif
1271 
1272 	raw_spin_unlock_irqrestore(&desc->lock, flags);
1273 
1274 	unregister_handler_proc(irq, action);
1275 
1276 	/* Make sure it's not being used on another CPU: */
1277 	synchronize_irq(irq);
1278 
1279 #ifdef CONFIG_DEBUG_SHIRQ
1280 	/*
1281 	 * It's a shared IRQ -- the driver ought to be prepared for an IRQ
1282 	 * event to happen even now it's being freed, so let's make sure that
1283 	 * is so by doing an extra call to the handler ....
1284 	 *
1285 	 * ( We do this after actually deregistering it, to make sure that a
1286 	 *   'real' IRQ doesn't run in * parallel with our fake. )
1287 	 */
1288 	if (action->flags & IRQF_SHARED) {
1289 		local_irq_save(flags);
1290 		action->handler(irq, dev_id);
1291 		local_irq_restore(flags);
1292 	}
1293 #endif
1294 
1295 	if (action->thread) {
1296 		kthread_stop(action->thread);
1297 		put_task_struct(action->thread);
1298 	}
1299 
1300 	module_put(desc->owner);
1301 	return action;
1302 }
1303 
1304 /**
1305  *	remove_irq - free an interrupt
1306  *	@irq: Interrupt line to free
1307  *	@act: irqaction for the interrupt
1308  *
1309  * Used to remove interrupts statically setup by the early boot process.
1310  */
1311 void remove_irq(unsigned int irq, struct irqaction *act)
1312 {
1313 	struct irq_desc *desc = irq_to_desc(irq);
1314 
1315 	if (desc && !WARN_ON(irq_settings_is_per_cpu_devid(desc)))
1316 	    __free_irq(irq, act->dev_id);
1317 }
1318 EXPORT_SYMBOL_GPL(remove_irq);
1319 
1320 /**
1321  *	free_irq - free an interrupt allocated with request_irq
1322  *	@irq: Interrupt line to free
1323  *	@dev_id: Device identity to free
1324  *
1325  *	Remove an interrupt handler. The handler is removed and if the
1326  *	interrupt line is no longer in use by any driver it is disabled.
1327  *	On a shared IRQ the caller must ensure the interrupt is disabled
1328  *	on the card it drives before calling this function. The function
1329  *	does not return until any executing interrupts for this IRQ
1330  *	have completed.
1331  *
1332  *	This function must not be called from interrupt context.
1333  */
1334 void free_irq(unsigned int irq, void *dev_id)
1335 {
1336 	struct irq_desc *desc = irq_to_desc(irq);
1337 
1338 	if (!desc || WARN_ON(irq_settings_is_per_cpu_devid(desc)))
1339 		return;
1340 
1341 #ifdef CONFIG_SMP
1342 	if (WARN_ON(desc->affinity_notify))
1343 		desc->affinity_notify = NULL;
1344 #endif
1345 
1346 	chip_bus_lock(desc);
1347 	kfree(__free_irq(irq, dev_id));
1348 	chip_bus_sync_unlock(desc);
1349 }
1350 EXPORT_SYMBOL(free_irq);
1351 
1352 /**
1353  *	request_threaded_irq - allocate an interrupt line
1354  *	@irq: Interrupt line to allocate
1355  *	@handler: Function to be called when the IRQ occurs.
1356  *		  Primary handler for threaded interrupts
1357  *		  If NULL and thread_fn != NULL the default
1358  *		  primary handler is installed
1359  *	@thread_fn: Function called from the irq handler thread
1360  *		    If NULL, no irq thread is created
1361  *	@irqflags: Interrupt type flags
1362  *	@devname: An ascii name for the claiming device
1363  *	@dev_id: A cookie passed back to the handler function
1364  *
1365  *	This call allocates interrupt resources and enables the
1366  *	interrupt line and IRQ handling. From the point this
1367  *	call is made your handler function may be invoked. Since
1368  *	your handler function must clear any interrupt the board
1369  *	raises, you must take care both to initialise your hardware
1370  *	and to set up the interrupt handler in the right order.
1371  *
1372  *	If you want to set up a threaded irq handler for your device
1373  *	then you need to supply @handler and @thread_fn. @handler is
1374  *	still called in hard interrupt context and has to check
1375  *	whether the interrupt originates from the device. If yes it
1376  *	needs to disable the interrupt on the device and return
1377  *	IRQ_WAKE_THREAD which will wake up the handler thread and run
1378  *	@thread_fn. This split handler design is necessary to support
1379  *	shared interrupts.
1380  *
1381  *	Dev_id must be globally unique. Normally the address of the
1382  *	device data structure is used as the cookie. Since the handler
1383  *	receives this value it makes sense to use it.
1384  *
1385  *	If your interrupt is shared you must pass a non NULL dev_id
1386  *	as this is required when freeing the interrupt.
1387  *
1388  *	Flags:
1389  *
1390  *	IRQF_SHARED		Interrupt is shared
1391  *	IRQF_TRIGGER_*		Specify active edge(s) or level
1392  *
1393  */
1394 int request_threaded_irq(unsigned int irq, irq_handler_t handler,
1395 			 irq_handler_t thread_fn, unsigned long irqflags,
1396 			 const char *devname, void *dev_id)
1397 {
1398 	struct irqaction *action;
1399 	struct irq_desc *desc;
1400 	int retval;
1401 
1402 	/*
1403 	 * Sanity-check: shared interrupts must pass in a real dev-ID,
1404 	 * otherwise we'll have trouble later trying to figure out
1405 	 * which interrupt is which (messes up the interrupt freeing
1406 	 * logic etc).
1407 	 */
1408 	if ((irqflags & IRQF_SHARED) && !dev_id)
1409 		return -EINVAL;
1410 
1411 	desc = irq_to_desc(irq);
1412 	if (!desc)
1413 		return -EINVAL;
1414 
1415 	if (!irq_settings_can_request(desc) ||
1416 	    WARN_ON(irq_settings_is_per_cpu_devid(desc)))
1417 		return -EINVAL;
1418 
1419 	if (!handler) {
1420 		if (!thread_fn)
1421 			return -EINVAL;
1422 		handler = irq_default_primary_handler;
1423 	}
1424 
1425 	action = kzalloc(sizeof(struct irqaction), GFP_KERNEL);
1426 	if (!action)
1427 		return -ENOMEM;
1428 
1429 	action->handler = handler;
1430 	action->thread_fn = thread_fn;
1431 	action->flags = irqflags;
1432 	action->name = devname;
1433 	action->dev_id = dev_id;
1434 
1435 	chip_bus_lock(desc);
1436 	retval = __setup_irq(irq, desc, action);
1437 	chip_bus_sync_unlock(desc);
1438 
1439 	if (retval)
1440 		kfree(action);
1441 
1442 #ifdef CONFIG_DEBUG_SHIRQ_FIXME
1443 	if (!retval && (irqflags & IRQF_SHARED)) {
1444 		/*
1445 		 * It's a shared IRQ -- the driver ought to be prepared for it
1446 		 * to happen immediately, so let's make sure....
1447 		 * We disable the irq to make sure that a 'real' IRQ doesn't
1448 		 * run in parallel with our fake.
1449 		 */
1450 		unsigned long flags;
1451 
1452 		disable_irq(irq);
1453 		local_irq_save(flags);
1454 
1455 		handler(irq, dev_id);
1456 
1457 		local_irq_restore(flags);
1458 		enable_irq(irq);
1459 	}
1460 #endif
1461 	return retval;
1462 }
1463 EXPORT_SYMBOL(request_threaded_irq);
1464 
1465 /**
1466  *	request_any_context_irq - allocate an interrupt line
1467  *	@irq: Interrupt line to allocate
1468  *	@handler: Function to be called when the IRQ occurs.
1469  *		  Threaded handler for threaded interrupts.
1470  *	@flags: Interrupt type flags
1471  *	@name: An ascii name for the claiming device
1472  *	@dev_id: A cookie passed back to the handler function
1473  *
1474  *	This call allocates interrupt resources and enables the
1475  *	interrupt line and IRQ handling. It selects either a
1476  *	hardirq or threaded handling method depending on the
1477  *	context.
1478  *
1479  *	On failure, it returns a negative value. On success,
1480  *	it returns either IRQC_IS_HARDIRQ or IRQC_IS_NESTED.
1481  */
1482 int request_any_context_irq(unsigned int irq, irq_handler_t handler,
1483 			    unsigned long flags, const char *name, void *dev_id)
1484 {
1485 	struct irq_desc *desc = irq_to_desc(irq);
1486 	int ret;
1487 
1488 	if (!desc)
1489 		return -EINVAL;
1490 
1491 	if (irq_settings_is_nested_thread(desc)) {
1492 		ret = request_threaded_irq(irq, NULL, handler,
1493 					   flags, name, dev_id);
1494 		return !ret ? IRQC_IS_NESTED : ret;
1495 	}
1496 
1497 	ret = request_irq(irq, handler, flags, name, dev_id);
1498 	return !ret ? IRQC_IS_HARDIRQ : ret;
1499 }
1500 EXPORT_SYMBOL_GPL(request_any_context_irq);
1501 
1502 void enable_percpu_irq(unsigned int irq, unsigned int type)
1503 {
1504 	unsigned int cpu = smp_processor_id();
1505 	unsigned long flags;
1506 	struct irq_desc *desc = irq_get_desc_lock(irq, &flags, IRQ_GET_DESC_CHECK_PERCPU);
1507 
1508 	if (!desc)
1509 		return;
1510 
1511 	type &= IRQ_TYPE_SENSE_MASK;
1512 	if (type != IRQ_TYPE_NONE) {
1513 		int ret;
1514 
1515 		ret = __irq_set_trigger(desc, irq, type);
1516 
1517 		if (ret) {
1518 			WARN(1, "failed to set type for IRQ%d\n", irq);
1519 			goto out;
1520 		}
1521 	}
1522 
1523 	irq_percpu_enable(desc, cpu);
1524 out:
1525 	irq_put_desc_unlock(desc, flags);
1526 }
1527 
1528 void disable_percpu_irq(unsigned int irq)
1529 {
1530 	unsigned int cpu = smp_processor_id();
1531 	unsigned long flags;
1532 	struct irq_desc *desc = irq_get_desc_lock(irq, &flags, IRQ_GET_DESC_CHECK_PERCPU);
1533 
1534 	if (!desc)
1535 		return;
1536 
1537 	irq_percpu_disable(desc, cpu);
1538 	irq_put_desc_unlock(desc, flags);
1539 }
1540 
1541 /*
1542  * Internal function to unregister a percpu irqaction.
1543  */
1544 static struct irqaction *__free_percpu_irq(unsigned int irq, void __percpu *dev_id)
1545 {
1546 	struct irq_desc *desc = irq_to_desc(irq);
1547 	struct irqaction *action;
1548 	unsigned long flags;
1549 
1550 	WARN(in_interrupt(), "Trying to free IRQ %d from IRQ context!\n", irq);
1551 
1552 	if (!desc)
1553 		return NULL;
1554 
1555 	raw_spin_lock_irqsave(&desc->lock, flags);
1556 
1557 	action = desc->action;
1558 	if (!action || action->percpu_dev_id != dev_id) {
1559 		WARN(1, "Trying to free already-free IRQ %d\n", irq);
1560 		goto bad;
1561 	}
1562 
1563 	if (!cpumask_empty(desc->percpu_enabled)) {
1564 		WARN(1, "percpu IRQ %d still enabled on CPU%d!\n",
1565 		     irq, cpumask_first(desc->percpu_enabled));
1566 		goto bad;
1567 	}
1568 
1569 	/* Found it - now remove it from the list of entries: */
1570 	desc->action = NULL;
1571 
1572 	raw_spin_unlock_irqrestore(&desc->lock, flags);
1573 
1574 	unregister_handler_proc(irq, action);
1575 
1576 	module_put(desc->owner);
1577 	return action;
1578 
1579 bad:
1580 	raw_spin_unlock_irqrestore(&desc->lock, flags);
1581 	return NULL;
1582 }
1583 
1584 /**
1585  *	remove_percpu_irq - free a per-cpu interrupt
1586  *	@irq: Interrupt line to free
1587  *	@act: irqaction for the interrupt
1588  *
1589  * Used to remove interrupts statically setup by the early boot process.
1590  */
1591 void remove_percpu_irq(unsigned int irq, struct irqaction *act)
1592 {
1593 	struct irq_desc *desc = irq_to_desc(irq);
1594 
1595 	if (desc && irq_settings_is_per_cpu_devid(desc))
1596 	    __free_percpu_irq(irq, act->percpu_dev_id);
1597 }
1598 
1599 /**
1600  *	free_percpu_irq - free an interrupt allocated with request_percpu_irq
1601  *	@irq: Interrupt line to free
1602  *	@dev_id: Device identity to free
1603  *
1604  *	Remove a percpu interrupt handler. The handler is removed, but
1605  *	the interrupt line is not disabled. This must be done on each
1606  *	CPU before calling this function. The function does not return
1607  *	until any executing interrupts for this IRQ have completed.
1608  *
1609  *	This function must not be called from interrupt context.
1610  */
1611 void free_percpu_irq(unsigned int irq, void __percpu *dev_id)
1612 {
1613 	struct irq_desc *desc = irq_to_desc(irq);
1614 
1615 	if (!desc || !irq_settings_is_per_cpu_devid(desc))
1616 		return;
1617 
1618 	chip_bus_lock(desc);
1619 	kfree(__free_percpu_irq(irq, dev_id));
1620 	chip_bus_sync_unlock(desc);
1621 }
1622 
1623 /**
1624  *	setup_percpu_irq - setup a per-cpu interrupt
1625  *	@irq: Interrupt line to setup
1626  *	@act: irqaction for the interrupt
1627  *
1628  * Used to statically setup per-cpu interrupts in the early boot process.
1629  */
1630 int setup_percpu_irq(unsigned int irq, struct irqaction *act)
1631 {
1632 	struct irq_desc *desc = irq_to_desc(irq);
1633 	int retval;
1634 
1635 	if (!desc || !irq_settings_is_per_cpu_devid(desc))
1636 		return -EINVAL;
1637 	chip_bus_lock(desc);
1638 	retval = __setup_irq(irq, desc, act);
1639 	chip_bus_sync_unlock(desc);
1640 
1641 	return retval;
1642 }
1643 
1644 /**
1645  *	request_percpu_irq - allocate a percpu interrupt line
1646  *	@irq: Interrupt line to allocate
1647  *	@handler: Function to be called when the IRQ occurs.
1648  *	@devname: An ascii name for the claiming device
1649  *	@dev_id: A percpu cookie passed back to the handler function
1650  *
1651  *	This call allocates interrupt resources, but doesn't
1652  *	automatically enable the interrupt. It has to be done on each
1653  *	CPU using enable_percpu_irq().
1654  *
1655  *	Dev_id must be globally unique. It is a per-cpu variable, and
1656  *	the handler gets called with the interrupted CPU's instance of
1657  *	that variable.
1658  */
1659 int request_percpu_irq(unsigned int irq, irq_handler_t handler,
1660 		       const char *devname, void __percpu *dev_id)
1661 {
1662 	struct irqaction *action;
1663 	struct irq_desc *desc;
1664 	int retval;
1665 
1666 	if (!dev_id)
1667 		return -EINVAL;
1668 
1669 	desc = irq_to_desc(irq);
1670 	if (!desc || !irq_settings_can_request(desc) ||
1671 	    !irq_settings_is_per_cpu_devid(desc))
1672 		return -EINVAL;
1673 
1674 	action = kzalloc(sizeof(struct irqaction), GFP_KERNEL);
1675 	if (!action)
1676 		return -ENOMEM;
1677 
1678 	action->handler = handler;
1679 	action->flags = IRQF_PERCPU | IRQF_NO_SUSPEND;
1680 	action->name = devname;
1681 	action->percpu_dev_id = dev_id;
1682 
1683 	chip_bus_lock(desc);
1684 	retval = __setup_irq(irq, desc, action);
1685 	chip_bus_sync_unlock(desc);
1686 
1687 	if (retval)
1688 		kfree(action);
1689 
1690 	return retval;
1691 }
1692