627d401c2979bbfd1c564098c4bb4223e1412452
[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/config.h>
11 #include <linux/irq.h>
12 #include <linux/module.h>
13 #include <linux/random.h>
14 #include <linux/interrupt.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
34         if (irq >= NR_IRQS)
35                 return;
36
37         while (desc->status & IRQ_INPROGRESS)
38                 cpu_relax();
39 }
40 EXPORT_SYMBOL(synchronize_irq);
41
42 #endif
43
44 /**
45  *      disable_irq_nosync - disable an irq without waiting
46  *      @irq: Interrupt to disable
47  *
48  *      Disable the selected interrupt line.  Disables and Enables are
49  *      nested.
50  *      Unlike disable_irq(), this function does not ensure existing
51  *      instances of the IRQ handler have completed before returning.
52  *
53  *      This function may be called from IRQ context.
54  */
55 void disable_irq_nosync(unsigned int irq)
56 {
57         struct irq_desc *desc = irq_desc + irq;
58         unsigned long flags;
59
60         if (irq >= NR_IRQS)
61                 return;
62
63         spin_lock_irqsave(&desc->lock, flags);
64         if (!desc->depth++) {
65                 desc->status |= IRQ_DISABLED;
66                 desc->chip->disable(irq);
67         }
68         spin_unlock_irqrestore(&desc->lock, flags);
69 }
70 EXPORT_SYMBOL(disable_irq_nosync);
71
72 /**
73  *      disable_irq - disable an irq and wait for completion
74  *      @irq: Interrupt to disable
75  *
76  *      Disable the selected interrupt line.  Enables and Disables are
77  *      nested.
78  *      This function waits for any pending IRQ handlers for this interrupt
79  *      to complete before returning. If you use this function while
80  *      holding a resource the IRQ handler may need you will deadlock.
81  *
82  *      This function may be called - with care - from IRQ context.
83  */
84 void disable_irq(unsigned int irq)
85 {
86         struct irq_desc *desc = irq_desc + irq;
87
88         if (irq >= NR_IRQS)
89                 return;
90
91         disable_irq_nosync(irq);
92         if (desc->action)
93                 synchronize_irq(irq);
94 }
95 EXPORT_SYMBOL(disable_irq);
96
97 /**
98  *      enable_irq - enable handling of an irq
99  *      @irq: Interrupt to enable
100  *
101  *      Undoes the effect of one call to disable_irq().  If this
102  *      matches the last disable, processing of interrupts on this
103  *      IRQ line is re-enabled.
104  *
105  *      This function may be called from IRQ context.
106  */
107 void enable_irq(unsigned int irq)
108 {
109         struct irq_desc *desc = irq_desc + irq;
110         unsigned long flags;
111
112         if (irq >= NR_IRQS)
113                 return;
114
115         spin_lock_irqsave(&desc->lock, flags);
116         switch (desc->depth) {
117         case 0:
118                 printk(KERN_WARNING "Unablanced enable_irq(%d)\n", irq);
119                 WARN_ON(1);
120                 break;
121         case 1: {
122                 unsigned int status = desc->status & ~IRQ_DISABLED;
123
124                 /* Prevent probing on this irq: */
125                 desc->status = status | IRQ_NOPROBE;
126                 check_irq_resend(desc, irq);
127                 /* fall-through */
128         }
129         default:
130                 desc->depth--;
131         }
132         spin_unlock_irqrestore(&desc->lock, flags);
133 }
134 EXPORT_SYMBOL(enable_irq);
135
136 /**
137  *      set_irq_wake - control irq power management wakeup
138  *      @irq:   interrupt to control
139  *      @on:    enable/disable power management wakeup
140  *
141  *      Enable/disable power management wakeup mode
142  */
143 int set_irq_wake(unsigned int irq, unsigned int on)
144 {
145         struct irq_desc *desc = irq_desc + irq;
146         unsigned long flags;
147         int ret = -ENXIO;
148
149         spin_lock_irqsave(&desc->lock, flags);
150         if (desc->chip->set_wake)
151                 ret = desc->chip->set_wake(irq, on);
152         spin_unlock_irqrestore(&desc->lock, flags);
153         return ret;
154 }
155 EXPORT_SYMBOL(set_irq_wake);
156
157 /*
158  * Internal function that tells the architecture code whether a
159  * particular irq has been exclusively allocated or is available
160  * for driver use.
161  */
162 int can_request_irq(unsigned int irq, unsigned long irqflags)
163 {
164         struct irqaction *action;
165
166         if (irq >= NR_IRQS || irq_desc[irq].status & IRQ_NOREQUEST)
167                 return 0;
168
169         action = irq_desc[irq].action;
170         if (action)
171                 if (irqflags & action->flags & SA_SHIRQ)
172                         action = NULL;
173
174         return !action;
175 }
176
177 void compat_irq_chip_set_default_handler(struct irq_desc *desc)
178 {
179         /*
180          * If the architecture still has not overriden
181          * the flow handler then zap the default. This
182          * should catch incorrect flow-type setting.
183          */
184         if (desc->handle_irq == &handle_bad_irq)
185                 desc->handle_irq = NULL;
186 }
187
188 /*
189  * Internal function to register an irqaction - typically used to
190  * allocate special interrupts that are part of the architecture.
191  */
192 int setup_irq(unsigned int irq, struct irqaction *new)
193 {
194         struct irq_desc *desc = irq_desc + irq;
195         struct irqaction *old, **p;
196         unsigned long flags;
197         int shared = 0;
198
199         if (irq >= NR_IRQS)
200                 return -EINVAL;
201
202         if (desc->chip == &no_irq_type)
203                 return -ENOSYS;
204         /*
205          * Some drivers like serial.c use request_irq() heavily,
206          * so we have to be careful not to interfere with a
207          * running system.
208          */
209         if (new->flags & SA_SAMPLE_RANDOM) {
210                 /*
211                  * This function might sleep, we want to call it first,
212                  * outside of the atomic block.
213                  * Yes, this might clear the entropy pool if the wrong
214                  * driver is attempted to be loaded, without actually
215                  * installing a new handler, but is this really a problem,
216                  * only the sysadmin is able to do this.
217                  */
218                 rand_initialize_irq(irq);
219         }
220
221         /*
222          * The following block of code has to be executed atomically
223          */
224         spin_lock_irqsave(&desc->lock, flags);
225         p = &desc->action;
226         old = *p;
227         if (old) {
228                 /*
229                  * Can't share interrupts unless both agree to and are
230                  * the same type (level, edge, polarity). So both flag
231                  * fields must have SA_SHIRQ set and the bits which
232                  * set the trigger type must match.
233                  */
234                 if (!((old->flags & new->flags) & SA_SHIRQ) ||
235                     ((old->flags ^ new->flags) & SA_TRIGGER_MASK))
236                         goto mismatch;
237
238 #if defined(CONFIG_IRQ_PER_CPU) && defined(SA_PERCPU_IRQ)
239                 /* All handlers must agree on per-cpuness */
240                 if ((old->flags & IRQ_PER_CPU) != (new->flags & IRQ_PER_CPU))
241                         goto mismatch;
242 #endif
243
244                 /* add new interrupt at end of irq queue */
245                 do {
246                         p = &old->next;
247                         old = *p;
248                 } while (old);
249                 shared = 1;
250         }
251
252         *p = new;
253 #if defined(CONFIG_IRQ_PER_CPU) && defined(SA_PERCPU_IRQ)
254         if (new->flags & SA_PERCPU_IRQ)
255                 desc->status |= IRQ_PER_CPU;
256 #endif
257         if (!shared) {
258                 irq_chip_set_defaults(desc->chip);
259
260                 /* Setup the type (level, edge polarity) if configured: */
261                 if (new->flags & SA_TRIGGER_MASK) {
262                         if (desc->chip && desc->chip->set_type)
263                                 desc->chip->set_type(irq,
264                                                 new->flags & SA_TRIGGER_MASK);
265                         else
266                                 /*
267                                  * SA_TRIGGER_* but the PIC does not support
268                                  * multiple flow-types?
269                                  */
270                                 printk(KERN_WARNING "setup_irq(%d) SA_TRIGGER"
271                                        "set. No set_type function available\n",
272                                        irq);
273                 } else
274                         compat_irq_chip_set_default_handler(desc);
275
276                 desc->status &= ~(IRQ_AUTODETECT | IRQ_WAITING |
277                                   IRQ_INPROGRESS);
278
279                 if (!(desc->status & IRQ_NOAUTOEN)) {
280                         desc->depth = 0;
281                         desc->status &= ~IRQ_DISABLED;
282                         if (desc->chip->startup)
283                                 desc->chip->startup(irq);
284                         else
285                                 desc->chip->enable(irq);
286                 } else
287                         /* Undo nested disables: */
288                         desc->depth = 1;
289         }
290         spin_unlock_irqrestore(&desc->lock, flags);
291
292         new->irq = irq;
293         register_irq_proc(irq);
294         new->dir = NULL;
295         register_handler_proc(irq, new);
296
297         return 0;
298
299 mismatch:
300         spin_unlock_irqrestore(&desc->lock, flags);
301         if (!(new->flags & SA_PROBEIRQ)) {
302                 printk(KERN_ERR "%s: irq handler mismatch\n", __FUNCTION__);
303                 dump_stack();
304         }
305         return -EBUSY;
306 }
307
308 /**
309  *      free_irq - free an interrupt
310  *      @irq: Interrupt line to free
311  *      @dev_id: Device identity to free
312  *
313  *      Remove an interrupt handler. The handler is removed and if the
314  *      interrupt line is no longer in use by any driver it is disabled.
315  *      On a shared IRQ the caller must ensure the interrupt is disabled
316  *      on the card it drives before calling this function. The function
317  *      does not return until any executing interrupts for this IRQ
318  *      have completed.
319  *
320  *      This function must not be called from interrupt context.
321  */
322 void free_irq(unsigned int irq, void *dev_id)
323 {
324         struct irq_desc *desc;
325         struct irqaction **p;
326         unsigned long flags;
327
328         WARN_ON(in_interrupt());
329         if (irq >= NR_IRQS)
330                 return;
331
332         desc = irq_desc + irq;
333         spin_lock_irqsave(&desc->lock, flags);
334         p = &desc->action;
335         for (;;) {
336                 struct irqaction *action = *p;
337
338                 if (action) {
339                         struct irqaction **pp = p;
340
341                         p = &action->next;
342                         if (action->dev_id != dev_id)
343                                 continue;
344
345                         /* Found it - now remove it from the list of entries */
346                         *pp = action->next;
347
348                         /* Currently used only by UML, might disappear one day.*/
349 #ifdef CONFIG_IRQ_RELEASE_METHOD
350                         if (desc->chip->release)
351                                 desc->chip->release(irq, dev_id);
352 #endif
353
354                         if (!desc->action) {
355                                 desc->status |= IRQ_DISABLED;
356                                 if (desc->chip->shutdown)
357                                         desc->chip->shutdown(irq);
358                                 else
359                                         desc->chip->disable(irq);
360                         }
361                         spin_unlock_irqrestore(&desc->lock, flags);
362                         unregister_handler_proc(irq, action);
363
364                         /* Make sure it's not being used on another CPU */
365                         synchronize_irq(irq);
366                         kfree(action);
367                         return;
368                 }
369                 printk(KERN_ERR "Trying to free free IRQ%d\n", irq);
370                 spin_unlock_irqrestore(&desc->lock, flags);
371                 return;
372         }
373 }
374 EXPORT_SYMBOL(free_irq);
375
376 /**
377  *      request_irq - allocate an interrupt line
378  *      @irq: Interrupt line to allocate
379  *      @handler: Function to be called when the IRQ occurs
380  *      @irqflags: Interrupt type flags
381  *      @devname: An ascii name for the claiming device
382  *      @dev_id: A cookie passed back to the handler function
383  *
384  *      This call allocates interrupt resources and enables the
385  *      interrupt line and IRQ handling. From the point this
386  *      call is made your handler function may be invoked. Since
387  *      your handler function must clear any interrupt the board
388  *      raises, you must take care both to initialise your hardware
389  *      and to set up the interrupt handler in the right order.
390  *
391  *      Dev_id must be globally unique. Normally the address of the
392  *      device data structure is used as the cookie. Since the handler
393  *      receives this value it makes sense to use it.
394  *
395  *      If your interrupt is shared you must pass a non NULL dev_id
396  *      as this is required when freeing the interrupt.
397  *
398  *      Flags:
399  *
400  *      SA_SHIRQ                Interrupt is shared
401  *      SA_INTERRUPT            Disable local interrupts while processing
402  *      SA_SAMPLE_RANDOM        The interrupt can be used for entropy
403  *
404  */
405 int request_irq(unsigned int irq,
406                 irqreturn_t (*handler)(int, void *, struct pt_regs *),
407                 unsigned long irqflags, const char *devname, void *dev_id)
408 {
409         struct irqaction *action;
410         int retval;
411
412         /*
413          * Sanity-check: shared interrupts must pass in a real dev-ID,
414          * otherwise we'll have trouble later trying to figure out
415          * which interrupt is which (messes up the interrupt freeing
416          * logic etc).
417          */
418         if ((irqflags & SA_SHIRQ) && !dev_id)
419                 return -EINVAL;
420         if (irq >= NR_IRQS)
421                 return -EINVAL;
422         if (irq_desc[irq].status & IRQ_NOREQUEST)
423                 return -EINVAL;
424         if (!handler)
425                 return -EINVAL;
426
427         action = kmalloc(sizeof(struct irqaction), GFP_ATOMIC);
428         if (!action)
429                 return -ENOMEM;
430
431         action->handler = handler;
432         action->flags = irqflags;
433         cpus_clear(action->mask);
434         action->name = devname;
435         action->next = NULL;
436         action->dev_id = dev_id;
437
438         select_smp_affinity(irq);
439
440         retval = setup_irq(irq, action);
441         if (retval)
442                 kfree(action);
443
444         return retval;
445 }
446 EXPORT_SYMBOL(request_irq);
447