xref: /openbmc/linux/kernel/irq/manage.c (revision 22246614)
1 /*
2  * linux/kernel/irq/manage.c
3  *
4  * Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
5  * Copyright (C) 2005-2006 Thomas Gleixner
6  *
7  * This file contains driver APIs to the irq subsystem.
8  */
9 
10 #include <linux/irq.h>
11 #include <linux/module.h>
12 #include <linux/random.h>
13 #include <linux/interrupt.h>
14 #include <linux/slab.h>
15 
16 #include "internals.h"
17 
18 #ifdef CONFIG_SMP
19 
20 /**
21  *	synchronize_irq - wait for pending IRQ handlers (on other CPUs)
22  *	@irq: interrupt number to wait for
23  *
24  *	This function waits for any pending IRQ handlers for this interrupt
25  *	to complete before returning. If you use this function while
26  *	holding a resource the IRQ handler may need you will deadlock.
27  *
28  *	This function may be called - with care - from IRQ context.
29  */
30 void synchronize_irq(unsigned int irq)
31 {
32 	struct irq_desc *desc = irq_desc + irq;
33 	unsigned int status;
34 
35 	if (irq >= NR_IRQS)
36 		return;
37 
38 	do {
39 		unsigned long flags;
40 
41 		/*
42 		 * Wait until we're out of the critical section.  This might
43 		 * give the wrong answer due to the lack of memory barriers.
44 		 */
45 		while (desc->status & IRQ_INPROGRESS)
46 			cpu_relax();
47 
48 		/* Ok, that indicated we're done: double-check carefully. */
49 		spin_lock_irqsave(&desc->lock, flags);
50 		status = desc->status;
51 		spin_unlock_irqrestore(&desc->lock, flags);
52 
53 		/* Oops, that failed? */
54 	} while (status & IRQ_INPROGRESS);
55 }
56 EXPORT_SYMBOL(synchronize_irq);
57 
58 /**
59  *	irq_can_set_affinity - Check if the affinity of a given irq can be set
60  *	@irq:		Interrupt to check
61  *
62  */
63 int irq_can_set_affinity(unsigned int irq)
64 {
65 	struct irq_desc *desc = irq_desc + irq;
66 
67 	if (CHECK_IRQ_PER_CPU(desc->status) || !desc->chip ||
68 	    !desc->chip->set_affinity)
69 		return 0;
70 
71 	return 1;
72 }
73 
74 /**
75  *	irq_set_affinity - Set the irq affinity of a given irq
76  *	@irq:		Interrupt to set affinity
77  *	@cpumask:	cpumask
78  *
79  */
80 int irq_set_affinity(unsigned int irq, cpumask_t cpumask)
81 {
82 	struct irq_desc *desc = irq_desc + irq;
83 
84 	if (!desc->chip->set_affinity)
85 		return -EINVAL;
86 
87 	set_balance_irq_affinity(irq, cpumask);
88 
89 #ifdef CONFIG_GENERIC_PENDING_IRQ
90 	set_pending_irq(irq, cpumask);
91 #else
92 	desc->affinity = cpumask;
93 	desc->chip->set_affinity(irq, cpumask);
94 #endif
95 	return 0;
96 }
97 
98 #endif
99 
100 /**
101  *	disable_irq_nosync - disable an irq without waiting
102  *	@irq: Interrupt to disable
103  *
104  *	Disable the selected interrupt line.  Disables and Enables are
105  *	nested.
106  *	Unlike disable_irq(), this function does not ensure existing
107  *	instances of the IRQ handler have completed before returning.
108  *
109  *	This function may be called from IRQ context.
110  */
111 void disable_irq_nosync(unsigned int irq)
112 {
113 	struct irq_desc *desc = irq_desc + irq;
114 	unsigned long flags;
115 
116 	if (irq >= NR_IRQS)
117 		return;
118 
119 	spin_lock_irqsave(&desc->lock, flags);
120 	if (!desc->depth++) {
121 		desc->status |= IRQ_DISABLED;
122 		desc->chip->disable(irq);
123 	}
124 	spin_unlock_irqrestore(&desc->lock, flags);
125 }
126 EXPORT_SYMBOL(disable_irq_nosync);
127 
128 /**
129  *	disable_irq - disable an irq and wait for completion
130  *	@irq: Interrupt to disable
131  *
132  *	Disable the selected interrupt line.  Enables and Disables are
133  *	nested.
134  *	This function waits for any pending IRQ handlers for this interrupt
135  *	to complete before returning. If you use this function while
136  *	holding a resource the IRQ handler may need you will deadlock.
137  *
138  *	This function may be called - with care - from IRQ context.
139  */
140 void disable_irq(unsigned int irq)
141 {
142 	struct irq_desc *desc = irq_desc + irq;
143 
144 	if (irq >= NR_IRQS)
145 		return;
146 
147 	disable_irq_nosync(irq);
148 	if (desc->action)
149 		synchronize_irq(irq);
150 }
151 EXPORT_SYMBOL(disable_irq);
152 
153 static void __enable_irq(struct irq_desc *desc, unsigned int irq)
154 {
155 	switch (desc->depth) {
156 	case 0:
157 		printk(KERN_WARNING "Unbalanced enable for IRQ %d\n", irq);
158 		WARN_ON(1);
159 		break;
160 	case 1: {
161 		unsigned int status = desc->status & ~IRQ_DISABLED;
162 
163 		/* Prevent probing on this irq: */
164 		desc->status = status | IRQ_NOPROBE;
165 		check_irq_resend(desc, irq);
166 		/* fall-through */
167 	}
168 	default:
169 		desc->depth--;
170 	}
171 }
172 
173 /**
174  *	enable_irq - enable handling of an irq
175  *	@irq: Interrupt to enable
176  *
177  *	Undoes the effect of one call to disable_irq().  If this
178  *	matches the last disable, processing of interrupts on this
179  *	IRQ line is re-enabled.
180  *
181  *	This function may be called from IRQ context.
182  */
183 void enable_irq(unsigned int irq)
184 {
185 	struct irq_desc *desc = irq_desc + irq;
186 	unsigned long flags;
187 
188 	if (irq >= NR_IRQS)
189 		return;
190 
191 	spin_lock_irqsave(&desc->lock, flags);
192 	__enable_irq(desc, irq);
193 	spin_unlock_irqrestore(&desc->lock, flags);
194 }
195 EXPORT_SYMBOL(enable_irq);
196 
197 /**
198  *	set_irq_wake - control irq power management wakeup
199  *	@irq:	interrupt to control
200  *	@on:	enable/disable power management wakeup
201  *
202  *	Enable/disable power management wakeup mode, which is
203  *	disabled by default.  Enables and disables must match,
204  *	just as they match for non-wakeup mode support.
205  *
206  *	Wakeup mode lets this IRQ wake the system from sleep
207  *	states like "suspend to RAM".
208  */
209 int set_irq_wake(unsigned int irq, unsigned int on)
210 {
211 	struct irq_desc *desc = irq_desc + irq;
212 	unsigned long flags;
213 	int ret = -ENXIO;
214 	int (*set_wake)(unsigned, unsigned) = desc->chip->set_wake;
215 
216 	/* wakeup-capable irqs can be shared between drivers that
217 	 * don't need to have the same sleep mode behaviors.
218 	 */
219 	spin_lock_irqsave(&desc->lock, flags);
220 	if (on) {
221 		if (desc->wake_depth++ == 0)
222 			desc->status |= IRQ_WAKEUP;
223 		else
224 			set_wake = NULL;
225 	} else {
226 		if (desc->wake_depth == 0) {
227 			printk(KERN_WARNING "Unbalanced IRQ %d "
228 					"wake disable\n", irq);
229 			WARN_ON(1);
230 		} else if (--desc->wake_depth == 0)
231 			desc->status &= ~IRQ_WAKEUP;
232 		else
233 			set_wake = NULL;
234 	}
235 	if (set_wake)
236 		ret = desc->chip->set_wake(irq, on);
237 	spin_unlock_irqrestore(&desc->lock, flags);
238 	return ret;
239 }
240 EXPORT_SYMBOL(set_irq_wake);
241 
242 /*
243  * Internal function that tells the architecture code whether a
244  * particular irq has been exclusively allocated or is available
245  * for driver use.
246  */
247 int can_request_irq(unsigned int irq, unsigned long irqflags)
248 {
249 	struct irqaction *action;
250 
251 	if (irq >= NR_IRQS || irq_desc[irq].status & IRQ_NOREQUEST)
252 		return 0;
253 
254 	action = irq_desc[irq].action;
255 	if (action)
256 		if (irqflags & action->flags & IRQF_SHARED)
257 			action = NULL;
258 
259 	return !action;
260 }
261 
262 void compat_irq_chip_set_default_handler(struct irq_desc *desc)
263 {
264 	/*
265 	 * If the architecture still has not overriden
266 	 * the flow handler then zap the default. This
267 	 * should catch incorrect flow-type setting.
268 	 */
269 	if (desc->handle_irq == &handle_bad_irq)
270 		desc->handle_irq = NULL;
271 }
272 
273 /*
274  * Internal function to register an irqaction - typically used to
275  * allocate special interrupts that are part of the architecture.
276  */
277 int setup_irq(unsigned int irq, struct irqaction *new)
278 {
279 	struct irq_desc *desc = irq_desc + irq;
280 	struct irqaction *old, **p;
281 	const char *old_name = NULL;
282 	unsigned long flags;
283 	int shared = 0;
284 
285 	if (irq >= NR_IRQS)
286 		return -EINVAL;
287 
288 	if (desc->chip == &no_irq_chip)
289 		return -ENOSYS;
290 	/*
291 	 * Some drivers like serial.c use request_irq() heavily,
292 	 * so we have to be careful not to interfere with a
293 	 * running system.
294 	 */
295 	if (new->flags & IRQF_SAMPLE_RANDOM) {
296 		/*
297 		 * This function might sleep, we want to call it first,
298 		 * outside of the atomic block.
299 		 * Yes, this might clear the entropy pool if the wrong
300 		 * driver is attempted to be loaded, without actually
301 		 * installing a new handler, but is this really a problem,
302 		 * only the sysadmin is able to do this.
303 		 */
304 		rand_initialize_irq(irq);
305 	}
306 
307 	/*
308 	 * The following block of code has to be executed atomically
309 	 */
310 	spin_lock_irqsave(&desc->lock, flags);
311 	p = &desc->action;
312 	old = *p;
313 	if (old) {
314 		/*
315 		 * Can't share interrupts unless both agree to and are
316 		 * the same type (level, edge, polarity). So both flag
317 		 * fields must have IRQF_SHARED set and the bits which
318 		 * set the trigger type must match.
319 		 */
320 		if (!((old->flags & new->flags) & IRQF_SHARED) ||
321 		    ((old->flags ^ new->flags) & IRQF_TRIGGER_MASK)) {
322 			old_name = old->name;
323 			goto mismatch;
324 		}
325 
326 #if defined(CONFIG_IRQ_PER_CPU)
327 		/* All handlers must agree on per-cpuness */
328 		if ((old->flags & IRQF_PERCPU) !=
329 		    (new->flags & IRQF_PERCPU))
330 			goto mismatch;
331 #endif
332 
333 		/* add new interrupt at end of irq queue */
334 		do {
335 			p = &old->next;
336 			old = *p;
337 		} while (old);
338 		shared = 1;
339 	}
340 
341 	*p = new;
342 
343 	/* Exclude IRQ from balancing */
344 	if (new->flags & IRQF_NOBALANCING)
345 		desc->status |= IRQ_NO_BALANCING;
346 
347 	if (!shared) {
348 		irq_chip_set_defaults(desc->chip);
349 
350 #if defined(CONFIG_IRQ_PER_CPU)
351 		if (new->flags & IRQF_PERCPU)
352 			desc->status |= IRQ_PER_CPU;
353 #endif
354 
355 		/* Setup the type (level, edge polarity) if configured: */
356 		if (new->flags & IRQF_TRIGGER_MASK) {
357 			if (desc->chip && desc->chip->set_type)
358 				desc->chip->set_type(irq,
359 						new->flags & IRQF_TRIGGER_MASK);
360 			else
361 				/*
362 				 * IRQF_TRIGGER_* but the PIC does not support
363 				 * multiple flow-types?
364 				 */
365 				printk(KERN_WARNING "No IRQF_TRIGGER set_type "
366 				       "function for IRQ %d (%s)\n", irq,
367 				       desc->chip ? desc->chip->name :
368 				       "unknown");
369 		} else
370 			compat_irq_chip_set_default_handler(desc);
371 
372 		desc->status &= ~(IRQ_AUTODETECT | IRQ_WAITING |
373 				  IRQ_INPROGRESS | IRQ_SPURIOUS_DISABLED);
374 
375 		if (!(desc->status & IRQ_NOAUTOEN)) {
376 			desc->depth = 0;
377 			desc->status &= ~IRQ_DISABLED;
378 			if (desc->chip->startup)
379 				desc->chip->startup(irq);
380 			else
381 				desc->chip->enable(irq);
382 		} else
383 			/* Undo nested disables: */
384 			desc->depth = 1;
385 	}
386 	/* Reset broken irq detection when installing new handler */
387 	desc->irq_count = 0;
388 	desc->irqs_unhandled = 0;
389 
390 	/*
391 	 * Check whether we disabled the irq via the spurious handler
392 	 * before. Reenable it and give it another chance.
393 	 */
394 	if (shared && (desc->status & IRQ_SPURIOUS_DISABLED)) {
395 		desc->status &= ~IRQ_SPURIOUS_DISABLED;
396 		__enable_irq(desc, irq);
397 	}
398 
399 	spin_unlock_irqrestore(&desc->lock, flags);
400 
401 	new->irq = irq;
402 	register_irq_proc(irq);
403 	new->dir = NULL;
404 	register_handler_proc(irq, new);
405 
406 	return 0;
407 
408 mismatch:
409 #ifdef CONFIG_DEBUG_SHIRQ
410 	if (!(new->flags & IRQF_PROBE_SHARED)) {
411 		printk(KERN_ERR "IRQ handler type mismatch for IRQ %d\n", irq);
412 		if (old_name)
413 			printk(KERN_ERR "current handler: %s\n", old_name);
414 		dump_stack();
415 	}
416 #endif
417 	spin_unlock_irqrestore(&desc->lock, flags);
418 	return -EBUSY;
419 }
420 
421 /**
422  *	free_irq - free an interrupt
423  *	@irq: Interrupt line to free
424  *	@dev_id: Device identity to free
425  *
426  *	Remove an interrupt handler. The handler is removed and if the
427  *	interrupt line is no longer in use by any driver it is disabled.
428  *	On a shared IRQ the caller must ensure the interrupt is disabled
429  *	on the card it drives before calling this function. The function
430  *	does not return until any executing interrupts for this IRQ
431  *	have completed.
432  *
433  *	This function must not be called from interrupt context.
434  */
435 void free_irq(unsigned int irq, void *dev_id)
436 {
437 	struct irq_desc *desc;
438 	struct irqaction **p;
439 	unsigned long flags;
440 
441 	WARN_ON(in_interrupt());
442 	if (irq >= NR_IRQS)
443 		return;
444 
445 	desc = irq_desc + irq;
446 	spin_lock_irqsave(&desc->lock, flags);
447 	p = &desc->action;
448 	for (;;) {
449 		struct irqaction *action = *p;
450 
451 		if (action) {
452 			struct irqaction **pp = p;
453 
454 			p = &action->next;
455 			if (action->dev_id != dev_id)
456 				continue;
457 
458 			/* Found it - now remove it from the list of entries */
459 			*pp = action->next;
460 
461 			/* Currently used only by UML, might disappear one day.*/
462 #ifdef CONFIG_IRQ_RELEASE_METHOD
463 			if (desc->chip->release)
464 				desc->chip->release(irq, dev_id);
465 #endif
466 
467 			if (!desc->action) {
468 				desc->status |= IRQ_DISABLED;
469 				if (desc->chip->shutdown)
470 					desc->chip->shutdown(irq);
471 				else
472 					desc->chip->disable(irq);
473 			}
474 			spin_unlock_irqrestore(&desc->lock, flags);
475 			unregister_handler_proc(irq, action);
476 
477 			/* Make sure it's not being used on another CPU */
478 			synchronize_irq(irq);
479 #ifdef CONFIG_DEBUG_SHIRQ
480 			/*
481 			 * It's a shared IRQ -- the driver ought to be
482 			 * prepared for it to happen even now it's
483 			 * being freed, so let's make sure....  We do
484 			 * this after actually deregistering it, to
485 			 * make sure that a 'real' IRQ doesn't run in
486 			 * parallel with our fake
487 			 */
488 			if (action->flags & IRQF_SHARED) {
489 				local_irq_save(flags);
490 				action->handler(irq, dev_id);
491 				local_irq_restore(flags);
492 			}
493 #endif
494 			kfree(action);
495 			return;
496 		}
497 		printk(KERN_ERR "Trying to free already-free IRQ %d\n", irq);
498 #ifdef CONFIG_DEBUG_SHIRQ
499 		dump_stack();
500 #endif
501 		spin_unlock_irqrestore(&desc->lock, flags);
502 		return;
503 	}
504 }
505 EXPORT_SYMBOL(free_irq);
506 
507 /**
508  *	request_irq - allocate an interrupt line
509  *	@irq: Interrupt line to allocate
510  *	@handler: Function to be called when the IRQ occurs
511  *	@irqflags: Interrupt type flags
512  *	@devname: An ascii name for the claiming device
513  *	@dev_id: A cookie passed back to the handler function
514  *
515  *	This call allocates interrupt resources and enables the
516  *	interrupt line and IRQ handling. From the point this
517  *	call is made your handler function may be invoked. Since
518  *	your handler function must clear any interrupt the board
519  *	raises, you must take care both to initialise your hardware
520  *	and to set up the interrupt handler in the right order.
521  *
522  *	Dev_id must be globally unique. Normally the address of the
523  *	device data structure is used as the cookie. Since the handler
524  *	receives this value it makes sense to use it.
525  *
526  *	If your interrupt is shared you must pass a non NULL dev_id
527  *	as this is required when freeing the interrupt.
528  *
529  *	Flags:
530  *
531  *	IRQF_SHARED		Interrupt is shared
532  *	IRQF_DISABLED	Disable local interrupts while processing
533  *	IRQF_SAMPLE_RANDOM	The interrupt can be used for entropy
534  *
535  */
536 int request_irq(unsigned int irq, irq_handler_t handler,
537 		unsigned long irqflags, const char *devname, void *dev_id)
538 {
539 	struct irqaction *action;
540 	int retval;
541 
542 #ifdef CONFIG_LOCKDEP
543 	/*
544 	 * Lockdep wants atomic interrupt handlers:
545 	 */
546 	irqflags |= IRQF_DISABLED;
547 #endif
548 	/*
549 	 * Sanity-check: shared interrupts must pass in a real dev-ID,
550 	 * otherwise we'll have trouble later trying to figure out
551 	 * which interrupt is which (messes up the interrupt freeing
552 	 * logic etc).
553 	 */
554 	if ((irqflags & IRQF_SHARED) && !dev_id)
555 		return -EINVAL;
556 	if (irq >= NR_IRQS)
557 		return -EINVAL;
558 	if (irq_desc[irq].status & IRQ_NOREQUEST)
559 		return -EINVAL;
560 	if (!handler)
561 		return -EINVAL;
562 
563 	action = kmalloc(sizeof(struct irqaction), GFP_ATOMIC);
564 	if (!action)
565 		return -ENOMEM;
566 
567 	action->handler = handler;
568 	action->flags = irqflags;
569 	cpus_clear(action->mask);
570 	action->name = devname;
571 	action->next = NULL;
572 	action->dev_id = dev_id;
573 
574 	select_smp_affinity(irq);
575 
576 #ifdef CONFIG_DEBUG_SHIRQ
577 	if (irqflags & IRQF_SHARED) {
578 		/*
579 		 * It's a shared IRQ -- the driver ought to be prepared for it
580 		 * to happen immediately, so let's make sure....
581 		 * We do this before actually registering it, to make sure that
582 		 * a 'real' IRQ doesn't run in parallel with our fake
583 		 */
584 		unsigned long flags;
585 
586 		local_irq_save(flags);
587 		handler(irq, dev_id);
588 		local_irq_restore(flags);
589 	}
590 #endif
591 
592 	retval = setup_irq(irq, action);
593 	if (retval)
594 		kfree(action);
595 
596 	return retval;
597 }
598 EXPORT_SYMBOL(request_irq);
599