[PATCH] Debug shared irqs
[linux-2.6.git] / kernel / irq / manage.c
1 /*
2  * linux/kernel/irq/manage.c
3  *
4  * Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
5  * Copyright (C) 2005-2006 Thomas Gleixner
6  *
7  * This file contains driver APIs to the irq subsystem.
8  */
9
10 #include <linux/irq.h>
11 #include <linux/module.h>
12 #include <linux/random.h>
13 #include <linux/interrupt.h>
14
15 #include "internals.h"
16
17 #ifdef CONFIG_SMP
18
19 /**
20  *      synchronize_irq - wait for pending IRQ handlers (on other CPUs)
21  *      @irq: interrupt number to wait for
22  *
23  *      This function waits for any pending IRQ handlers for this interrupt
24  *      to complete before returning. If you use this function while
25  *      holding a resource the IRQ handler may need you will deadlock.
26  *
27  *      This function may be called - with care - from IRQ context.
28  */
29 void synchronize_irq(unsigned int irq)
30 {
31         struct irq_desc *desc = irq_desc + irq;
32
33         if (irq >= NR_IRQS)
34                 return;
35
36         while (desc->status & IRQ_INPROGRESS)
37                 cpu_relax();
38 }
39 EXPORT_SYMBOL(synchronize_irq);
40
41 #endif
42
43 /**
44  *      disable_irq_nosync - disable an irq without waiting
45  *      @irq: Interrupt to disable
46  *
47  *      Disable the selected interrupt line.  Disables and Enables are
48  *      nested.
49  *      Unlike disable_irq(), this function does not ensure existing
50  *      instances of the IRQ handler have completed before returning.
51  *
52  *      This function may be called from IRQ context.
53  */
54 void disable_irq_nosync(unsigned int irq)
55 {
56         struct irq_desc *desc = irq_desc + irq;
57         unsigned long flags;
58
59         if (irq >= NR_IRQS)
60                 return;
61
62         spin_lock_irqsave(&desc->lock, flags);
63         if (!desc->depth++) {
64                 desc->status |= IRQ_DISABLED;
65                 desc->chip->disable(irq);
66         }
67         spin_unlock_irqrestore(&desc->lock, flags);
68 }
69 EXPORT_SYMBOL(disable_irq_nosync);
70
71 /**
72  *      disable_irq - disable an irq and wait for completion
73  *      @irq: Interrupt to disable
74  *
75  *      Disable the selected interrupt line.  Enables and Disables are
76  *      nested.
77  *      This function waits for any pending IRQ handlers for this interrupt
78  *      to complete before returning. If you use this function while
79  *      holding a resource the IRQ handler may need you will deadlock.
80  *
81  *      This function may be called - with care - from IRQ context.
82  */
83 void disable_irq(unsigned int irq)
84 {
85         struct irq_desc *desc = irq_desc + irq;
86
87         if (irq >= NR_IRQS)
88                 return;
89
90         disable_irq_nosync(irq);
91         if (desc->action)
92                 synchronize_irq(irq);
93 }
94 EXPORT_SYMBOL(disable_irq);
95
96 /**
97  *      enable_irq - enable handling of an irq
98  *      @irq: Interrupt to enable
99  *
100  *      Undoes the effect of one call to disable_irq().  If this
101  *      matches the last disable, processing of interrupts on this
102  *      IRQ line is re-enabled.
103  *
104  *      This function may be called from IRQ context.
105  */
106 void enable_irq(unsigned int irq)
107 {
108         struct irq_desc *desc = irq_desc + irq;
109         unsigned long flags;
110
111         if (irq >= NR_IRQS)
112                 return;
113
114         spin_lock_irqsave(&desc->lock, flags);
115         switch (desc->depth) {
116         case 0:
117                 printk(KERN_WARNING "Unbalanced enable for IRQ %d\n", irq);
118                 WARN_ON(1);
119                 break;
120         case 1: {
121                 unsigned int status = desc->status & ~IRQ_DISABLED;
122
123                 /* Prevent probing on this irq: */
124                 desc->status = status | IRQ_NOPROBE;
125                 check_irq_resend(desc, irq);
126                 /* fall-through */
127         }
128         default:
129                 desc->depth--;
130         }
131         spin_unlock_irqrestore(&desc->lock, flags);
132 }
133 EXPORT_SYMBOL(enable_irq);
134
135 /**
136  *      set_irq_wake - control irq power management wakeup
137  *      @irq:   interrupt to control
138  *      @on:    enable/disable power management wakeup
139  *
140  *      Enable/disable power management wakeup mode, which is
141  *      disabled by default.  Enables and disables must match,
142  *      just as they match for non-wakeup mode support.
143  *
144  *      Wakeup mode lets this IRQ wake the system from sleep
145  *      states like "suspend to RAM".
146  */
147 int set_irq_wake(unsigned int irq, unsigned int on)
148 {
149         struct irq_desc *desc = irq_desc + irq;
150         unsigned long flags;
151         int ret = -ENXIO;
152         int (*set_wake)(unsigned, unsigned) = desc->chip->set_wake;
153
154         /* wakeup-capable irqs can be shared between drivers that
155          * don't need to have the same sleep mode behaviors.
156          */
157         spin_lock_irqsave(&desc->lock, flags);
158         if (on) {
159                 if (desc->wake_depth++ == 0)
160                         desc->status |= IRQ_WAKEUP;
161                 else
162                         set_wake = NULL;
163         } else {
164                 if (desc->wake_depth == 0) {
165                         printk(KERN_WARNING "Unbalanced IRQ %d "
166                                         "wake disable\n", irq);
167                         WARN_ON(1);
168                 } else if (--desc->wake_depth == 0)
169                         desc->status &= ~IRQ_WAKEUP;
170                 else
171                         set_wake = NULL;
172         }
173         if (set_wake)
174                 ret = desc->chip->set_wake(irq, on);
175         spin_unlock_irqrestore(&desc->lock, flags);
176         return ret;
177 }
178 EXPORT_SYMBOL(set_irq_wake);
179
180 /*
181  * Internal function that tells the architecture code whether a
182  * particular irq has been exclusively allocated or is available
183  * for driver use.
184  */
185 int can_request_irq(unsigned int irq, unsigned long irqflags)
186 {
187         struct irqaction *action;
188
189         if (irq >= NR_IRQS || irq_desc[irq].status & IRQ_NOREQUEST)
190                 return 0;
191
192         action = irq_desc[irq].action;
193         if (action)
194                 if (irqflags & action->flags & IRQF_SHARED)
195                         action = NULL;
196
197         return !action;
198 }
199
200 void compat_irq_chip_set_default_handler(struct irq_desc *desc)
201 {
202         /*
203          * If the architecture still has not overriden
204          * the flow handler then zap the default. This
205          * should catch incorrect flow-type setting.
206          */
207         if (desc->handle_irq == &handle_bad_irq)
208                 desc->handle_irq = NULL;
209 }
210
211 /*
212  * Internal function to register an irqaction - typically used to
213  * allocate special interrupts that are part of the architecture.
214  */
215 int setup_irq(unsigned int irq, struct irqaction *new)
216 {
217         struct irq_desc *desc = irq_desc + irq;
218         struct irqaction *old, **p;
219         const char *old_name = NULL;
220         unsigned long flags;
221         int shared = 0;
222
223         if (irq >= NR_IRQS)
224                 return -EINVAL;
225
226         if (desc->chip == &no_irq_chip)
227                 return -ENOSYS;
228         /*
229          * Some drivers like serial.c use request_irq() heavily,
230          * so we have to be careful not to interfere with a
231          * running system.
232          */
233         if (new->flags & IRQF_SAMPLE_RANDOM) {
234                 /*
235                  * This function might sleep, we want to call it first,
236                  * outside of the atomic block.
237                  * Yes, this might clear the entropy pool if the wrong
238                  * driver is attempted to be loaded, without actually
239                  * installing a new handler, but is this really a problem,
240                  * only the sysadmin is able to do this.
241                  */
242                 rand_initialize_irq(irq);
243         }
244
245         /*
246          * The following block of code has to be executed atomically
247          */
248         spin_lock_irqsave(&desc->lock, flags);
249         p = &desc->action;
250         old = *p;
251         if (old) {
252                 /*
253                  * Can't share interrupts unless both agree to and are
254                  * the same type (level, edge, polarity). So both flag
255                  * fields must have IRQF_SHARED set and the bits which
256                  * set the trigger type must match.
257                  */
258                 if (!((old->flags & new->flags) & IRQF_SHARED) ||
259                     ((old->flags ^ new->flags) & IRQF_TRIGGER_MASK)) {
260                         old_name = old->name;
261                         goto mismatch;
262                 }
263
264 #if defined(CONFIG_IRQ_PER_CPU)
265                 /* All handlers must agree on per-cpuness */
266                 if ((old->flags & IRQF_PERCPU) !=
267                     (new->flags & IRQF_PERCPU))
268                         goto mismatch;
269 #endif
270
271                 /* add new interrupt at end of irq queue */
272                 do {
273                         p = &old->next;
274                         old = *p;
275                 } while (old);
276                 shared = 1;
277         }
278
279         *p = new;
280 #if defined(CONFIG_IRQ_PER_CPU)
281         if (new->flags & IRQF_PERCPU)
282                 desc->status |= IRQ_PER_CPU;
283 #endif
284         if (!shared) {
285                 irq_chip_set_defaults(desc->chip);
286
287                 /* Setup the type (level, edge polarity) if configured: */
288                 if (new->flags & IRQF_TRIGGER_MASK) {
289                         if (desc->chip && desc->chip->set_type)
290                                 desc->chip->set_type(irq,
291                                                 new->flags & IRQF_TRIGGER_MASK);
292                         else
293                                 /*
294                                  * IRQF_TRIGGER_* but the PIC does not support
295                                  * multiple flow-types?
296                                  */
297                                 printk(KERN_WARNING "No IRQF_TRIGGER set_type "
298                                        "function for IRQ %d (%s)\n", irq,
299                                        desc->chip ? desc->chip->name :
300                                        "unknown");
301                 } else
302                         compat_irq_chip_set_default_handler(desc);
303
304                 desc->status &= ~(IRQ_AUTODETECT | IRQ_WAITING |
305                                   IRQ_INPROGRESS);
306
307                 if (!(desc->status & IRQ_NOAUTOEN)) {
308                         desc->depth = 0;
309                         desc->status &= ~IRQ_DISABLED;
310                         if (desc->chip->startup)
311                                 desc->chip->startup(irq);
312                         else
313                                 desc->chip->enable(irq);
314                 } else
315                         /* Undo nested disables: */
316                         desc->depth = 1;
317         }
318         /* Reset broken irq detection when installing new handler */
319         desc->irq_count = 0;
320         desc->irqs_unhandled = 0;
321         spin_unlock_irqrestore(&desc->lock, flags);
322
323         new->irq = irq;
324         register_irq_proc(irq);
325         new->dir = NULL;
326         register_handler_proc(irq, new);
327
328         return 0;
329
330 mismatch:
331         if (!(new->flags & IRQF_PROBE_SHARED)) {
332                 printk(KERN_ERR "IRQ handler type mismatch for IRQ %d\n", irq);
333                 if (old_name)
334                         printk(KERN_ERR "current handler: %s\n", old_name);
335                 dump_stack();
336         }
337         spin_unlock_irqrestore(&desc->lock, flags);
338         return -EBUSY;
339 }
340
341 /**
342  *      free_irq - free an interrupt
343  *      @irq: Interrupt line to free
344  *      @dev_id: Device identity to free
345  *
346  *      Remove an interrupt handler. The handler is removed and if the
347  *      interrupt line is no longer in use by any driver it is disabled.
348  *      On a shared IRQ the caller must ensure the interrupt is disabled
349  *      on the card it drives before calling this function. The function
350  *      does not return until any executing interrupts for this IRQ
351  *      have completed.
352  *
353  *      This function must not be called from interrupt context.
354  */
355 void free_irq(unsigned int irq, void *dev_id)
356 {
357         struct irq_desc *desc;
358         struct irqaction **p;
359         unsigned long flags;
360         irqreturn_t (*handler)(int, void *) = NULL;
361
362         WARN_ON(in_interrupt());
363         if (irq >= NR_IRQS)
364                 return;
365
366         desc = irq_desc + irq;
367         spin_lock_irqsave(&desc->lock, flags);
368         p = &desc->action;
369         for (;;) {
370                 struct irqaction *action = *p;
371
372                 if (action) {
373                         struct irqaction **pp = p;
374
375                         p = &action->next;
376                         if (action->dev_id != dev_id)
377                                 continue;
378
379                         /* Found it - now remove it from the list of entries */
380                         *pp = action->next;
381
382                         /* Currently used only by UML, might disappear one day.*/
383 #ifdef CONFIG_IRQ_RELEASE_METHOD
384                         if (desc->chip->release)
385                                 desc->chip->release(irq, dev_id);
386 #endif
387
388                         if (!desc->action) {
389                                 desc->status |= IRQ_DISABLED;
390                                 if (desc->chip->shutdown)
391                                         desc->chip->shutdown(irq);
392                                 else
393                                         desc->chip->disable(irq);
394                         }
395                         spin_unlock_irqrestore(&desc->lock, flags);
396                         unregister_handler_proc(irq, action);
397
398                         /* Make sure it's not being used on another CPU */
399                         synchronize_irq(irq);
400                         if (action->flags & IRQF_SHARED)
401                                 handler = action->handler;
402                         kfree(action);
403                         return;
404                 }
405                 printk(KERN_ERR "Trying to free already-free IRQ %d\n", irq);
406                 spin_unlock_irqrestore(&desc->lock, flags);
407                 return;
408         }
409 #ifdef CONFIG_DEBUG_SHIRQ
410         if (handler) {
411                 /*
412                  * It's a shared IRQ -- the driver ought to be prepared for it
413                  * to happen even now it's being freed, so let's make sure....
414                  * We do this after actually deregistering it, to make sure that
415                  * a 'real' IRQ doesn't run in parallel with our fake
416                  */
417                 handler(irq, dev_id);
418         }
419 #endif
420 }
421 EXPORT_SYMBOL(free_irq);
422
423 /**
424  *      request_irq - allocate an interrupt line
425  *      @irq: Interrupt line to allocate
426  *      @handler: Function to be called when the IRQ occurs
427  *      @irqflags: Interrupt type flags
428  *      @devname: An ascii name for the claiming device
429  *      @dev_id: A cookie passed back to the handler function
430  *
431  *      This call allocates interrupt resources and enables the
432  *      interrupt line and IRQ handling. From the point this
433  *      call is made your handler function may be invoked. Since
434  *      your handler function must clear any interrupt the board
435  *      raises, you must take care both to initialise your hardware
436  *      and to set up the interrupt handler in the right order.
437  *
438  *      Dev_id must be globally unique. Normally the address of the
439  *      device data structure is used as the cookie. Since the handler
440  *      receives this value it makes sense to use it.
441  *
442  *      If your interrupt is shared you must pass a non NULL dev_id
443  *      as this is required when freeing the interrupt.
444  *
445  *      Flags:
446  *
447  *      IRQF_SHARED             Interrupt is shared
448  *      IRQF_DISABLED   Disable local interrupts while processing
449  *      IRQF_SAMPLE_RANDOM      The interrupt can be used for entropy
450  *
451  */
452 int request_irq(unsigned int irq, irq_handler_t handler,
453                 unsigned long irqflags, const char *devname, void *dev_id)
454 {
455         struct irqaction *action;
456         int retval;
457
458 #ifdef CONFIG_LOCKDEP
459         /*
460          * Lockdep wants atomic interrupt handlers:
461          */
462         irqflags |= SA_INTERRUPT;
463 #endif
464         /*
465          * Sanity-check: shared interrupts must pass in a real dev-ID,
466          * otherwise we'll have trouble later trying to figure out
467          * which interrupt is which (messes up the interrupt freeing
468          * logic etc).
469          */
470         if ((irqflags & IRQF_SHARED) && !dev_id)
471                 return -EINVAL;
472         if (irq >= NR_IRQS)
473                 return -EINVAL;
474         if (irq_desc[irq].status & IRQ_NOREQUEST)
475                 return -EINVAL;
476         if (!handler)
477                 return -EINVAL;
478
479         action = kmalloc(sizeof(struct irqaction), GFP_ATOMIC);
480         if (!action)
481                 return -ENOMEM;
482
483         action->handler = handler;
484         action->flags = irqflags;
485         cpus_clear(action->mask);
486         action->name = devname;
487         action->next = NULL;
488         action->dev_id = dev_id;
489
490         select_smp_affinity(irq);
491
492 #ifdef CONFIG_DEBUG_SHIRQ
493         if (irqflags & IRQF_SHARED) {
494                 /*
495                  * It's a shared IRQ -- the driver ought to be prepared for it
496                  * to happen immediately, so let's make sure....
497                  * We do this before actually registering it, to make sure that
498                  * a 'real' IRQ doesn't run in parallel with our fake
499                  */
500                 if (irqflags & IRQF_DISABLED) {
501                         unsigned long flags;
502
503                         local_irq_save(flags);
504                         handler(irq, dev_id);
505                         local_irq_restore(flags);
506                 } else
507                         handler(irq, dev_id);
508         }
509 #endif
510
511         retval = setup_irq(irq, action);
512         if (retval)
513                 kfree(action);
514
515         return retval;
516 }
517 EXPORT_SYMBOL(request_irq);