[PATCH] IRQ type flags
[linux-2.6.git] / arch / arm / kernel / irq.c
1 /*
2  *  linux/arch/arm/kernel/irq.c
3  *
4  *  Copyright (C) 1992 Linus Torvalds
5  *  Modifications for ARM processor Copyright (C) 1995-2000 Russell King.
6  *
7  *  Support for Dynamic Tick Timer Copyright (C) 2004-2005 Nokia Corporation.
8  *  Dynamic Tick Timer written by Tony Lindgren <tony@atomide.com> and
9  *  Tuukka Tikkanen <tuukka.tikkanen@elektrobit.com>.
10  *
11  * This program is free software; you can redistribute it and/or modify
12  * it under the terms of the GNU General Public License version 2 as
13  * published by the Free Software Foundation.
14  *
15  *  This file contains the code used by various IRQ handling routines:
16  *  asking for different IRQ's should be done through these routines
17  *  instead of just grabbing them. Thus setups with different IRQ numbers
18  *  shouldn't result in any weird surprises, and installing new handlers
19  *  should be easier.
20  *
21  *  IRQ's are in fact implemented a bit like signal handlers for the kernel.
22  *  Naturally it's not a 1:1 relation, but there are similarities.
23  */
24 #include <linux/config.h>
25 #include <linux/kernel_stat.h>
26 #include <linux/module.h>
27 #include <linux/signal.h>
28 #include <linux/ioport.h>
29 #include <linux/interrupt.h>
30 #include <linux/ptrace.h>
31 #include <linux/slab.h>
32 #include <linux/random.h>
33 #include <linux/smp.h>
34 #include <linux/init.h>
35 #include <linux/seq_file.h>
36 #include <linux/errno.h>
37 #include <linux/list.h>
38 #include <linux/kallsyms.h>
39 #include <linux/proc_fs.h>
40
41 #include <asm/irq.h>
42 #include <asm/system.h>
43 #include <asm/mach/irq.h>
44 #include <asm/mach/time.h>
45
46 /*
47  * Maximum IRQ count.  Currently, this is arbitary.  However, it should
48  * not be set too low to prevent false triggering.  Conversely, if it
49  * is set too high, then you could miss a stuck IRQ.
50  *
51  * Maybe we ought to set a timer and re-enable the IRQ at a later time?
52  */
53 #define MAX_IRQ_CNT     100000
54
55 static int noirqdebug;
56 static volatile unsigned long irq_err_count;
57 static DEFINE_SPINLOCK(irq_controller_lock);
58 static LIST_HEAD(irq_pending);
59
60 struct irqdesc irq_desc[NR_IRQS];
61 void (*init_arch_irq)(void) __initdata = NULL;
62
63 /*
64  * No architecture-specific irq_finish function defined in arm/arch/irqs.h.
65  */
66 #ifndef irq_finish
67 #define irq_finish(irq) do { } while (0)
68 #endif
69
70 /*
71  * Dummy mask/unmask handler
72  */
73 void dummy_mask_unmask_irq(unsigned int irq)
74 {
75 }
76
77 irqreturn_t no_action(int irq, void *dev_id, struct pt_regs *regs)
78 {
79         return IRQ_NONE;
80 }
81
82 void do_bad_IRQ(unsigned int irq, struct irqdesc *desc, struct pt_regs *regs)
83 {
84         irq_err_count += 1;
85         printk(KERN_ERR "IRQ: spurious interrupt %d\n", irq);
86 }
87
88 static struct irqchip bad_chip = {
89         .ack    = dummy_mask_unmask_irq,
90         .mask   = dummy_mask_unmask_irq,
91         .unmask = dummy_mask_unmask_irq,
92 };
93
94 static struct irqdesc bad_irq_desc = {
95         .chip           = &bad_chip,
96         .handle         = do_bad_IRQ,
97         .pend           = LIST_HEAD_INIT(bad_irq_desc.pend),
98         .disable_depth  = 1,
99 };
100
101 #ifdef CONFIG_SMP
102 void synchronize_irq(unsigned int irq)
103 {
104         struct irqdesc *desc = irq_desc + irq;
105
106         while (desc->running)
107                 barrier();
108 }
109 EXPORT_SYMBOL(synchronize_irq);
110
111 #define smp_set_running(desc)   do { desc->running = 1; } while (0)
112 #define smp_clear_running(desc) do { desc->running = 0; } while (0)
113 #else
114 #define smp_set_running(desc)   do { } while (0)
115 #define smp_clear_running(desc) do { } while (0)
116 #endif
117
118 /**
119  *      disable_irq_nosync - disable an irq without waiting
120  *      @irq: Interrupt to disable
121  *
122  *      Disable the selected interrupt line.  Enables and disables
123  *      are nested.  We do this lazily.
124  *
125  *      This function may be called from IRQ context.
126  */
127 void disable_irq_nosync(unsigned int irq)
128 {
129         struct irqdesc *desc = irq_desc + irq;
130         unsigned long flags;
131
132         spin_lock_irqsave(&irq_controller_lock, flags);
133         desc->disable_depth++;
134         list_del_init(&desc->pend);
135         spin_unlock_irqrestore(&irq_controller_lock, flags);
136 }
137 EXPORT_SYMBOL(disable_irq_nosync);
138
139 /**
140  *      disable_irq - disable an irq and wait for completion
141  *      @irq: Interrupt to disable
142  *
143  *      Disable the selected interrupt line.  Enables and disables
144  *      are nested.  This functions waits for any pending IRQ
145  *      handlers for this interrupt to complete before returning.
146  *      If you use this function while holding a resource the IRQ
147  *      handler may need you will deadlock.
148  *
149  *      This function may be called - with care - from IRQ context.
150  */
151 void disable_irq(unsigned int irq)
152 {
153         struct irqdesc *desc = irq_desc + irq;
154
155         disable_irq_nosync(irq);
156         if (desc->action)
157                 synchronize_irq(irq);
158 }
159 EXPORT_SYMBOL(disable_irq);
160
161 /**
162  *      enable_irq - enable interrupt handling on an irq
163  *      @irq: Interrupt to enable
164  *
165  *      Re-enables the processing of interrupts on this IRQ line.
166  *      Note that this may call the interrupt handler, so you may
167  *      get unexpected results if you hold IRQs disabled.
168  *
169  *      This function may be called from IRQ context.
170  */
171 void enable_irq(unsigned int irq)
172 {
173         struct irqdesc *desc = irq_desc + irq;
174         unsigned long flags;
175
176         spin_lock_irqsave(&irq_controller_lock, flags);
177         if (unlikely(!desc->disable_depth)) {
178                 printk("enable_irq(%u) unbalanced from %p\n", irq,
179                         __builtin_return_address(0));
180         } else if (!--desc->disable_depth) {
181                 desc->probing = 0;
182                 desc->chip->unmask(irq);
183
184                 /*
185                  * If the interrupt is waiting to be processed,
186                  * try to re-run it.  We can't directly run it
187                  * from here since the caller might be in an
188                  * interrupt-protected region.
189                  */
190                 if (desc->pending && list_empty(&desc->pend)) {
191                         desc->pending = 0;
192                         if (!desc->chip->retrigger ||
193                             desc->chip->retrigger(irq))
194                                 list_add(&desc->pend, &irq_pending);
195                 }
196         }
197         spin_unlock_irqrestore(&irq_controller_lock, flags);
198 }
199 EXPORT_SYMBOL(enable_irq);
200
201 /*
202  * Enable wake on selected irq
203  */
204 void enable_irq_wake(unsigned int irq)
205 {
206         struct irqdesc *desc = irq_desc + irq;
207         unsigned long flags;
208
209         spin_lock_irqsave(&irq_controller_lock, flags);
210         if (desc->chip->set_wake)
211                 desc->chip->set_wake(irq, 1);
212         spin_unlock_irqrestore(&irq_controller_lock, flags);
213 }
214 EXPORT_SYMBOL(enable_irq_wake);
215
216 void disable_irq_wake(unsigned int irq)
217 {
218         struct irqdesc *desc = irq_desc + irq;
219         unsigned long flags;
220
221         spin_lock_irqsave(&irq_controller_lock, flags);
222         if (desc->chip->set_wake)
223                 desc->chip->set_wake(irq, 0);
224         spin_unlock_irqrestore(&irq_controller_lock, flags);
225 }
226 EXPORT_SYMBOL(disable_irq_wake);
227
228 int show_interrupts(struct seq_file *p, void *v)
229 {
230         int i = *(loff_t *) v, cpu;
231         struct irqaction * action;
232         unsigned long flags;
233
234         if (i == 0) {
235                 char cpuname[12];
236
237                 seq_printf(p, "    ");
238                 for_each_present_cpu(cpu) {
239                         sprintf(cpuname, "CPU%d", cpu);
240                         seq_printf(p, " %10s", cpuname);
241                 }
242                 seq_putc(p, '\n');
243         }
244
245         if (i < NR_IRQS) {
246                 spin_lock_irqsave(&irq_controller_lock, flags);
247                 action = irq_desc[i].action;
248                 if (!action)
249                         goto unlock;
250
251                 seq_printf(p, "%3d: ", i);
252                 for_each_present_cpu(cpu)
253                         seq_printf(p, "%10u ", kstat_cpu(cpu).irqs[i]);
254                 seq_printf(p, "  %s", action->name);
255                 for (action = action->next; action; action = action->next)
256                         seq_printf(p, ", %s", action->name);
257
258                 seq_putc(p, '\n');
259 unlock:
260                 spin_unlock_irqrestore(&irq_controller_lock, flags);
261         } else if (i == NR_IRQS) {
262 #ifdef CONFIG_ARCH_ACORN
263                 show_fiq_list(p, v);
264 #endif
265 #ifdef CONFIG_SMP
266                 show_ipi_list(p);
267                 show_local_irqs(p);
268 #endif
269                 seq_printf(p, "Err: %10lu\n", irq_err_count);
270         }
271         return 0;
272 }
273
274 /*
275  * IRQ lock detection.
276  *
277  * Hopefully, this should get us out of a few locked situations.
278  * However, it may take a while for this to happen, since we need
279  * a large number if IRQs to appear in the same jiffie with the
280  * same instruction pointer (or within 2 instructions).
281  */
282 static int check_irq_lock(struct irqdesc *desc, int irq, struct pt_regs *regs)
283 {
284         unsigned long instr_ptr = instruction_pointer(regs);
285
286         if (desc->lck_jif == jiffies &&
287             desc->lck_pc >= instr_ptr && desc->lck_pc < instr_ptr + 8) {
288                 desc->lck_cnt += 1;
289
290                 if (desc->lck_cnt > MAX_IRQ_CNT) {
291                         printk(KERN_ERR "IRQ LOCK: IRQ%d is locking the system, disabled\n", irq);
292                         return 1;
293                 }
294         } else {
295                 desc->lck_cnt = 0;
296                 desc->lck_pc  = instruction_pointer(regs);
297                 desc->lck_jif = jiffies;
298         }
299         return 0;
300 }
301
302 static void
303 report_bad_irq(unsigned int irq, struct pt_regs *regs, struct irqdesc *desc, int ret)
304 {
305         static int count = 100;
306         struct irqaction *action;
307
308         if (!count || noirqdebug)
309                 return;
310
311         count--;
312
313         if (ret != IRQ_HANDLED && ret != IRQ_NONE) {
314                 printk("irq%u: bogus retval mask %x\n", irq, ret);
315         } else {
316                 printk("irq%u: nobody cared\n", irq);
317         }
318         show_regs(regs);
319         dump_stack();
320         printk(KERN_ERR "handlers:");
321         action = desc->action;
322         do {
323                 printk("\n" KERN_ERR "[<%p>]", action->handler);
324                 print_symbol(" (%s)", (unsigned long)action->handler);
325                 action = action->next;
326         } while (action);
327         printk("\n");
328 }
329
330 static int
331 __do_irq(unsigned int irq, struct irqaction *action, struct pt_regs *regs)
332 {
333         unsigned int status;
334         int ret, retval = 0;
335
336         spin_unlock(&irq_controller_lock);
337
338 #ifdef CONFIG_NO_IDLE_HZ
339         if (!(action->flags & SA_TIMER) && system_timer->dyn_tick != NULL) {
340                 write_seqlock(&xtime_lock);
341                 if (system_timer->dyn_tick->state & DYN_TICK_ENABLED)
342                         system_timer->dyn_tick->handler(irq, 0, regs);
343                 write_sequnlock(&xtime_lock);
344         }
345 #endif
346
347         if (!(action->flags & SA_INTERRUPT))
348                 local_irq_enable();
349
350         status = 0;
351         do {
352                 ret = action->handler(irq, action->dev_id, regs);
353                 if (ret == IRQ_HANDLED)
354                         status |= action->flags;
355                 retval |= ret;
356                 action = action->next;
357         } while (action);
358
359         if (status & SA_SAMPLE_RANDOM)
360                 add_interrupt_randomness(irq);
361
362         spin_lock_irq(&irq_controller_lock);
363
364         return retval;
365 }
366
367 /*
368  * This is for software-decoded IRQs.  The caller is expected to
369  * handle the ack, clear, mask and unmask issues.
370  */
371 void
372 do_simple_IRQ(unsigned int irq, struct irqdesc *desc, struct pt_regs *regs)
373 {
374         struct irqaction *action;
375         const unsigned int cpu = smp_processor_id();
376
377         desc->triggered = 1;
378
379         kstat_cpu(cpu).irqs[irq]++;
380
381         smp_set_running(desc);
382
383         action = desc->action;
384         if (action) {
385                 int ret = __do_irq(irq, action, regs);
386                 if (ret != IRQ_HANDLED)
387                         report_bad_irq(irq, regs, desc, ret);
388         }
389
390         smp_clear_running(desc);
391 }
392
393 /*
394  * Most edge-triggered IRQ implementations seem to take a broken
395  * approach to this.  Hence the complexity.
396  */
397 void
398 do_edge_IRQ(unsigned int irq, struct irqdesc *desc, struct pt_regs *regs)
399 {
400         const unsigned int cpu = smp_processor_id();
401
402         desc->triggered = 1;
403
404         /*
405          * If we're currently running this IRQ, or its disabled,
406          * we shouldn't process the IRQ.  Instead, turn on the
407          * hardware masks.
408          */
409         if (unlikely(desc->running || desc->disable_depth))
410                 goto running;
411
412         /*
413          * Acknowledge and clear the IRQ, but don't mask it.
414          */
415         desc->chip->ack(irq);
416
417         /*
418          * Mark the IRQ currently in progress.
419          */
420         desc->running = 1;
421
422         kstat_cpu(cpu).irqs[irq]++;
423
424         do {
425                 struct irqaction *action;
426
427                 action = desc->action;
428                 if (!action)
429                         break;
430
431                 if (desc->pending && !desc->disable_depth) {
432                         desc->pending = 0;
433                         desc->chip->unmask(irq);
434                 }
435
436                 __do_irq(irq, action, regs);
437         } while (desc->pending && !desc->disable_depth);
438
439         desc->running = 0;
440
441         /*
442          * If we were disabled or freed, shut down the handler.
443          */
444         if (likely(desc->action && !check_irq_lock(desc, irq, regs)))
445                 return;
446
447  running:
448         /*
449          * We got another IRQ while this one was masked or
450          * currently running.  Delay it.
451          */
452         desc->pending = 1;
453         desc->chip->mask(irq);
454         desc->chip->ack(irq);
455 }
456
457 /*
458  * Level-based IRQ handler.  Nice and simple.
459  */
460 void
461 do_level_IRQ(unsigned int irq, struct irqdesc *desc, struct pt_regs *regs)
462 {
463         struct irqaction *action;
464         const unsigned int cpu = smp_processor_id();
465
466         desc->triggered = 1;
467
468         /*
469          * Acknowledge, clear _AND_ disable the interrupt.
470          */
471         desc->chip->ack(irq);
472
473         if (likely(!desc->disable_depth)) {
474                 kstat_cpu(cpu).irqs[irq]++;
475
476                 smp_set_running(desc);
477
478                 /*
479                  * Return with this interrupt masked if no action
480                  */
481                 action = desc->action;
482                 if (action) {
483                         int ret = __do_irq(irq, desc->action, regs);
484
485                         if (ret != IRQ_HANDLED)
486                                 report_bad_irq(irq, regs, desc, ret);
487
488                         if (likely(!desc->disable_depth &&
489                                    !check_irq_lock(desc, irq, regs)))
490                                 desc->chip->unmask(irq);
491                 }
492
493                 smp_clear_running(desc);
494         }
495 }
496
497 static void do_pending_irqs(struct pt_regs *regs)
498 {
499         struct list_head head, *l, *n;
500
501         do {
502                 struct irqdesc *desc;
503
504                 /*
505                  * First, take the pending interrupts off the list.
506                  * The act of calling the handlers may add some IRQs
507                  * back onto the list.
508                  */
509                 head = irq_pending;
510                 INIT_LIST_HEAD(&irq_pending);
511                 head.next->prev = &head;
512                 head.prev->next = &head;
513
514                 /*
515                  * Now run each entry.  We must delete it from our
516                  * list before calling the handler.
517                  */
518                 list_for_each_safe(l, n, &head) {
519                         desc = list_entry(l, struct irqdesc, pend);
520                         list_del_init(&desc->pend);
521                         desc_handle_irq(desc - irq_desc, desc, regs);
522                 }
523
524                 /*
525                  * The list must be empty.
526                  */
527                 BUG_ON(!list_empty(&head));
528         } while (!list_empty(&irq_pending));
529 }
530
531 /*
532  * do_IRQ handles all hardware IRQ's.  Decoded IRQs should not
533  * come via this function.  Instead, they should provide their
534  * own 'handler'
535  */
536 asmlinkage void asm_do_IRQ(unsigned int irq, struct pt_regs *regs)
537 {
538         struct irqdesc *desc = irq_desc + irq;
539
540         /*
541          * Some hardware gives randomly wrong interrupts.  Rather
542          * than crashing, do something sensible.
543          */
544         if (irq >= NR_IRQS)
545                 desc = &bad_irq_desc;
546
547         irq_enter();
548         spin_lock(&irq_controller_lock);
549         desc_handle_irq(irq, desc, regs);
550
551         /*
552          * Now re-run any pending interrupts.
553          */
554         if (!list_empty(&irq_pending))
555                 do_pending_irqs(regs);
556
557         irq_finish(irq);
558
559         spin_unlock(&irq_controller_lock);
560         irq_exit();
561 }
562
563 void __set_irq_handler(unsigned int irq, irq_handler_t handle, int is_chained)
564 {
565         struct irqdesc *desc;
566         unsigned long flags;
567
568         if (irq >= NR_IRQS) {
569                 printk(KERN_ERR "Trying to install handler for IRQ%d\n", irq);
570                 return;
571         }
572
573         if (handle == NULL)
574                 handle = do_bad_IRQ;
575
576         desc = irq_desc + irq;
577
578         if (is_chained && desc->chip == &bad_chip)
579                 printk(KERN_WARNING "Trying to install chained handler for IRQ%d\n", irq);
580
581         spin_lock_irqsave(&irq_controller_lock, flags);
582         if (handle == do_bad_IRQ) {
583                 desc->chip->mask(irq);
584                 desc->chip->ack(irq);
585                 desc->disable_depth = 1;
586         }
587         desc->handle = handle;
588         if (handle != do_bad_IRQ && is_chained) {
589                 desc->valid = 0;
590                 desc->probe_ok = 0;
591                 desc->disable_depth = 0;
592                 desc->chip->unmask(irq);
593         }
594         spin_unlock_irqrestore(&irq_controller_lock, flags);
595 }
596
597 void set_irq_chip(unsigned int irq, struct irqchip *chip)
598 {
599         struct irqdesc *desc;
600         unsigned long flags;
601
602         if (irq >= NR_IRQS) {
603                 printk(KERN_ERR "Trying to install chip for IRQ%d\n", irq);
604                 return;
605         }
606
607         if (chip == NULL)
608                 chip = &bad_chip;
609
610         desc = irq_desc + irq;
611         spin_lock_irqsave(&irq_controller_lock, flags);
612         desc->chip = chip;
613         spin_unlock_irqrestore(&irq_controller_lock, flags);
614 }
615
616 int set_irq_type(unsigned int irq, unsigned int type)
617 {
618         struct irqdesc *desc;
619         unsigned long flags;
620         int ret = -ENXIO;
621
622         if (irq >= NR_IRQS) {
623                 printk(KERN_ERR "Trying to set irq type for IRQ%d\n", irq);
624                 return -ENODEV;
625         }
626
627         desc = irq_desc + irq;
628         if (desc->chip->set_type) {
629                 spin_lock_irqsave(&irq_controller_lock, flags);
630                 ret = desc->chip->set_type(irq, type);
631                 spin_unlock_irqrestore(&irq_controller_lock, flags);
632         }
633
634         return ret;
635 }
636 EXPORT_SYMBOL(set_irq_type);
637
638 void set_irq_flags(unsigned int irq, unsigned int iflags)
639 {
640         struct irqdesc *desc;
641         unsigned long flags;
642
643         if (irq >= NR_IRQS) {
644                 printk(KERN_ERR "Trying to set irq flags for IRQ%d\n", irq);
645                 return;
646         }
647
648         desc = irq_desc + irq;
649         spin_lock_irqsave(&irq_controller_lock, flags);
650         desc->valid = (iflags & IRQF_VALID) != 0;
651         desc->probe_ok = (iflags & IRQF_PROBE) != 0;
652         desc->noautoenable = (iflags & IRQF_NOAUTOEN) != 0;
653         spin_unlock_irqrestore(&irq_controller_lock, flags);
654 }
655
656 int setup_irq(unsigned int irq, struct irqaction *new)
657 {
658         int shared = 0;
659         struct irqaction *old, **p;
660         unsigned long flags;
661         struct irqdesc *desc;
662
663         /*
664          * Some drivers like serial.c use request_irq() heavily,
665          * so we have to be careful not to interfere with a
666          * running system.
667          */
668         if (new->flags & SA_SAMPLE_RANDOM) {
669                 /*
670                  * This function might sleep, we want to call it first,
671                  * outside of the atomic block.
672                  * Yes, this might clear the entropy pool if the wrong
673                  * driver is attempted to be loaded, without actually
674                  * installing a new handler, but is this really a problem,
675                  * only the sysadmin is able to do this.
676                  */
677                 rand_initialize_irq(irq);
678         }
679
680         /*
681          * The following block of code has to be executed atomically
682          */
683         desc = irq_desc + irq;
684         spin_lock_irqsave(&irq_controller_lock, flags);
685         p = &desc->action;
686         if ((old = *p) != NULL) {
687                 /*
688                  * Can't share interrupts unless both agree to and are
689                  * the same type.
690                  */
691                 if (!(old->flags & new->flags & SA_SHIRQ) ||
692                     (~old->flags & new->flags) & SA_TRIGGER_MASK) {
693                         spin_unlock_irqrestore(&irq_controller_lock, flags);
694                         return -EBUSY;
695                 }
696
697                 /* add new interrupt at end of irq queue */
698                 do {
699                         p = &old->next;
700                         old = *p;
701                 } while (old);
702                 shared = 1;
703         }
704
705         *p = new;
706
707         if (!shared) {
708                 desc->probing = 0;
709                 desc->running = 0;
710                 desc->pending = 0;
711                 desc->disable_depth = 1;
712
713                 if (new->flags & SA_TRIGGER_MASK) {
714                         unsigned int type = new->flags & SA_TRIGGER_MASK;
715                         desc->chip->set_type(irq, type);
716                 }
717
718                 if (!desc->noautoenable) {
719                         desc->disable_depth = 0;
720                         desc->chip->unmask(irq);
721                 }
722         }
723
724         spin_unlock_irqrestore(&irq_controller_lock, flags);
725         return 0;
726 }
727
728 /**
729  *      request_irq - allocate an interrupt line
730  *      @irq: Interrupt line to allocate
731  *      @handler: Function to be called when the IRQ occurs
732  *      @irqflags: Interrupt type flags
733  *      @devname: An ascii name for the claiming device
734  *      @dev_id: A cookie passed back to the handler function
735  *
736  *      This call allocates interrupt resources and enables the
737  *      interrupt line and IRQ handling. From the point this
738  *      call is made your handler function may be invoked. Since
739  *      your handler function must clear any interrupt the board
740  *      raises, you must take care both to initialise your hardware
741  *      and to set up the interrupt handler in the right order.
742  *
743  *      Dev_id must be globally unique. Normally the address of the
744  *      device data structure is used as the cookie. Since the handler
745  *      receives this value it makes sense to use it.
746  *
747  *      If your interrupt is shared you must pass a non NULL dev_id
748  *      as this is required when freeing the interrupt.
749  *
750  *      Flags:
751  *
752  *      SA_SHIRQ                Interrupt is shared
753  *
754  *      SA_INTERRUPT            Disable local interrupts while processing
755  *
756  *      SA_SAMPLE_RANDOM        The interrupt can be used for entropy
757  *
758  */
759 int request_irq(unsigned int irq, irqreturn_t (*handler)(int, void *, struct pt_regs *),
760                  unsigned long irq_flags, const char * devname, void *dev_id)
761 {
762         unsigned long retval;
763         struct irqaction *action;
764
765         if (irq >= NR_IRQS || !irq_desc[irq].valid || !handler ||
766             (irq_flags & SA_SHIRQ && !dev_id))
767                 return -EINVAL;
768
769         action = (struct irqaction *)kmalloc(sizeof(struct irqaction), GFP_KERNEL);
770         if (!action)
771                 return -ENOMEM;
772
773         action->handler = handler;
774         action->flags = irq_flags;
775         cpus_clear(action->mask);
776         action->name = devname;
777         action->next = NULL;
778         action->dev_id = dev_id;
779
780         retval = setup_irq(irq, action);
781
782         if (retval)
783                 kfree(action);
784         return retval;
785 }
786
787 EXPORT_SYMBOL(request_irq);
788
789 /**
790  *      free_irq - free an interrupt
791  *      @irq: Interrupt line to free
792  *      @dev_id: Device identity to free
793  *
794  *      Remove an interrupt handler. The handler is removed and if the
795  *      interrupt line is no longer in use by any driver it is disabled.
796  *      On a shared IRQ the caller must ensure the interrupt is disabled
797  *      on the card it drives before calling this function.
798  *
799  *      This function must not be called from interrupt context.
800  */
801 void free_irq(unsigned int irq, void *dev_id)
802 {
803         struct irqaction * action, **p;
804         unsigned long flags;
805
806         if (irq >= NR_IRQS || !irq_desc[irq].valid) {
807                 printk(KERN_ERR "Trying to free IRQ%d\n",irq);
808                 dump_stack();
809                 return;
810         }
811
812         spin_lock_irqsave(&irq_controller_lock, flags);
813         for (p = &irq_desc[irq].action; (action = *p) != NULL; p = &action->next) {
814                 if (action->dev_id != dev_id)
815                         continue;
816
817                 /* Found it - now free it */
818                 *p = action->next;
819                 break;
820         }
821         spin_unlock_irqrestore(&irq_controller_lock, flags);
822
823         if (!action) {
824                 printk(KERN_ERR "Trying to free free IRQ%d\n",irq);
825                 dump_stack();
826         } else {
827                 synchronize_irq(irq);
828                 kfree(action);
829         }
830 }
831
832 EXPORT_SYMBOL(free_irq);
833
834 static DECLARE_MUTEX(probe_sem);
835
836 /* Start the interrupt probing.  Unlike other architectures,
837  * we don't return a mask of interrupts from probe_irq_on,
838  * but return the number of interrupts enabled for the probe.
839  * The interrupts which have been enabled for probing is
840  * instead recorded in the irq_desc structure.
841  */
842 unsigned long probe_irq_on(void)
843 {
844         unsigned int i, irqs = 0;
845         unsigned long delay;
846
847         down(&probe_sem);
848
849         /*
850          * first snaffle up any unassigned but
851          * probe-able interrupts
852          */
853         spin_lock_irq(&irq_controller_lock);
854         for (i = 0; i < NR_IRQS; i++) {
855                 if (!irq_desc[i].probe_ok || irq_desc[i].action)
856                         continue;
857
858                 irq_desc[i].probing = 1;
859                 irq_desc[i].triggered = 0;
860                 if (irq_desc[i].chip->set_type)
861                         irq_desc[i].chip->set_type(i, IRQT_PROBE);
862                 irq_desc[i].chip->unmask(i);
863                 irqs += 1;
864         }
865         spin_unlock_irq(&irq_controller_lock);
866
867         /*
868          * wait for spurious interrupts to mask themselves out again
869          */
870         for (delay = jiffies + HZ/10; time_before(jiffies, delay); )
871                 /* min 100ms delay */;
872
873         /*
874          * now filter out any obviously spurious interrupts
875          */
876         spin_lock_irq(&irq_controller_lock);
877         for (i = 0; i < NR_IRQS; i++) {
878                 if (irq_desc[i].probing && irq_desc[i].triggered) {
879                         irq_desc[i].probing = 0;
880                         irqs -= 1;
881                 }
882         }
883         spin_unlock_irq(&irq_controller_lock);
884
885         return irqs;
886 }
887
888 EXPORT_SYMBOL(probe_irq_on);
889
890 unsigned int probe_irq_mask(unsigned long irqs)
891 {
892         unsigned int mask = 0, i;
893
894         spin_lock_irq(&irq_controller_lock);
895         for (i = 0; i < 16 && i < NR_IRQS; i++)
896                 if (irq_desc[i].probing && irq_desc[i].triggered)
897                         mask |= 1 << i;
898         spin_unlock_irq(&irq_controller_lock);
899
900         up(&probe_sem);
901
902         return mask;
903 }
904 EXPORT_SYMBOL(probe_irq_mask);
905
906 /*
907  * Possible return values:
908  *  >= 0 - interrupt number
909  *    -1 - no interrupt/many interrupts
910  */
911 int probe_irq_off(unsigned long irqs)
912 {
913         unsigned int i;
914         int irq_found = NO_IRQ;
915
916         /*
917          * look at the interrupts, and find exactly one
918          * that we were probing has been triggered
919          */
920         spin_lock_irq(&irq_controller_lock);
921         for (i = 0; i < NR_IRQS; i++) {
922                 if (irq_desc[i].probing &&
923                     irq_desc[i].triggered) {
924                         if (irq_found != NO_IRQ) {
925                                 irq_found = NO_IRQ;
926                                 goto out;
927                         }
928                         irq_found = i;
929                 }
930         }
931
932         if (irq_found == -1)
933                 irq_found = NO_IRQ;
934 out:
935         spin_unlock_irq(&irq_controller_lock);
936
937         up(&probe_sem);
938
939         return irq_found;
940 }
941
942 EXPORT_SYMBOL(probe_irq_off);
943
944 #ifdef CONFIG_SMP
945 static void route_irq(struct irqdesc *desc, unsigned int irq, unsigned int cpu)
946 {
947         pr_debug("IRQ%u: moving from cpu%u to cpu%u\n", irq, desc->cpu, cpu);
948
949         spin_lock_irq(&irq_controller_lock);
950         desc->cpu = cpu;
951         desc->chip->set_cpu(desc, irq, cpu);
952         spin_unlock_irq(&irq_controller_lock);
953 }
954
955 #ifdef CONFIG_PROC_FS
956 static int
957 irq_affinity_read_proc(char *page, char **start, off_t off, int count,
958                        int *eof, void *data)
959 {
960         struct irqdesc *desc = irq_desc + ((int)data);
961         int len = cpumask_scnprintf(page, count, desc->affinity);
962
963         if (count - len < 2)
964                 return -EINVAL;
965         page[len++] = '\n';
966         page[len] = '\0';
967
968         return len;
969 }
970
971 static int
972 irq_affinity_write_proc(struct file *file, const char __user *buffer,
973                         unsigned long count, void *data)
974 {
975         unsigned int irq = (unsigned int)data;
976         struct irqdesc *desc = irq_desc + irq;
977         cpumask_t affinity, tmp;
978         int ret = -EIO;
979
980         if (!desc->chip->set_cpu)
981                 goto out;
982
983         ret = cpumask_parse(buffer, count, affinity);
984         if (ret)
985                 goto out;
986
987         cpus_and(tmp, affinity, cpu_online_map);
988         if (cpus_empty(tmp)) {
989                 ret = -EINVAL;
990                 goto out;
991         }
992
993         desc->affinity = affinity;
994         route_irq(desc, irq, first_cpu(tmp));
995         ret = count;
996
997  out:
998         return ret;
999 }
1000 #endif
1001 #endif
1002
1003 void __init init_irq_proc(void)
1004 {
1005 #if defined(CONFIG_SMP) && defined(CONFIG_PROC_FS)
1006         struct proc_dir_entry *dir;
1007         int irq;
1008
1009         dir = proc_mkdir("irq", NULL);
1010         if (!dir)
1011                 return;
1012
1013         for (irq = 0; irq < NR_IRQS; irq++) {
1014                 struct proc_dir_entry *entry;
1015                 struct irqdesc *desc;
1016                 char name[16];
1017
1018                 desc = irq_desc + irq;
1019                 memset(name, 0, sizeof(name));
1020                 snprintf(name, sizeof(name) - 1, "%u", irq);
1021
1022                 desc->procdir = proc_mkdir(name, dir);
1023                 if (!desc->procdir)
1024                         continue;
1025
1026                 entry = create_proc_entry("smp_affinity", 0600, desc->procdir);
1027                 if (entry) {
1028                         entry->nlink = 1;
1029                         entry->data = (void *)irq;
1030                         entry->read_proc = irq_affinity_read_proc;
1031                         entry->write_proc = irq_affinity_write_proc;
1032                 }
1033         }
1034 #endif
1035 }
1036
1037 void __init init_IRQ(void)
1038 {
1039         struct irqdesc *desc;
1040         int irq;
1041
1042 #ifdef CONFIG_SMP
1043         bad_irq_desc.affinity = CPU_MASK_ALL;
1044         bad_irq_desc.cpu = smp_processor_id();
1045 #endif
1046
1047         for (irq = 0, desc = irq_desc; irq < NR_IRQS; irq++, desc++) {
1048                 *desc = bad_irq_desc;
1049                 INIT_LIST_HEAD(&desc->pend);
1050         }
1051
1052         init_arch_irq();
1053 }
1054
1055 static int __init noirqdebug_setup(char *str)
1056 {
1057         noirqdebug = 1;
1058         return 1;
1059 }
1060
1061 __setup("noirqdebug", noirqdebug_setup);
1062
1063 #ifdef CONFIG_HOTPLUG_CPU
1064 /*
1065  * The CPU has been marked offline.  Migrate IRQs off this CPU.  If
1066  * the affinity settings do not allow other CPUs, force them onto any
1067  * available CPU.
1068  */
1069 void migrate_irqs(void)
1070 {
1071         unsigned int i, cpu = smp_processor_id();
1072
1073         for (i = 0; i < NR_IRQS; i++) {
1074                 struct irqdesc *desc = irq_desc + i;
1075
1076                 if (desc->cpu == cpu) {
1077                         unsigned int newcpu = any_online_cpu(desc->affinity);
1078
1079                         if (newcpu == NR_CPUS) {
1080                                 if (printk_ratelimit())
1081                                         printk(KERN_INFO "IRQ%u no longer affine to CPU%u\n",
1082                                                i, cpu);
1083
1084                                 cpus_setall(desc->affinity);
1085                                 newcpu = any_online_cpu(desc->affinity);
1086                         }
1087
1088                         route_irq(desc, i, newcpu);
1089                 }
1090         }
1091 }
1092 #endif /* CONFIG_HOTPLUG_CPU */