Linux-2.6.12-rc2
[linux-2.6.git] / arch / arm26 / 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  *  'Borrowed' for ARM26 and (C) 2003 Ian Molton.
7  *
8  * This program is free software; you can redistribute it and/or modify
9  * it under the terms of the GNU General Public License version 2 as
10  * published by the Free Software Foundation.
11  *
12  *  This file contains the code used by various IRQ handling routines:
13  *  asking for different IRQ's should be done through these routines
14  *  instead of just grabbing them. Thus setups with different IRQ numbers
15  *  shouldn't result in any weird surprises, and installing new handlers
16  *  should be easier.
17  *
18  *  IRQ's are in fact implemented a bit like signal handlers for the kernel.
19  *  Naturally it's not a 1:1 relation, but there are similarities.
20  */
21 #include <linux/config.h>
22 #include <linux/module.h>
23 #include <linux/ptrace.h>
24 #include <linux/kernel_stat.h>
25 #include <linux/signal.h>
26 #include <linux/sched.h>
27 #include <linux/ioport.h>
28 #include <linux/interrupt.h>
29 #include <linux/slab.h>
30 #include <linux/random.h>
31 #include <linux/smp.h>
32 #include <linux/init.h>
33 #include <linux/seq_file.h>
34 #include <linux/errno.h>
35
36 #include <asm/irq.h>
37 #include <asm/system.h>
38 #include <asm/irqchip.h>
39
40 //FIXME - this ought to be in a header IMO
41 void __init arc_init_irq(void);
42
43 /*
44  * Maximum IRQ count.  Currently, this is arbitary.  However, it should
45  * not be set too low to prevent false triggering.  Conversely, if it
46  * is set too high, then you could miss a stuck IRQ.
47  *
48  * FIXME Maybe we ought to set a timer and re-enable the IRQ at a later time?
49  */
50 #define MAX_IRQ_CNT     100000
51
52 static volatile unsigned long irq_err_count;
53 static DEFINE_SPINLOCK(irq_controller_lock);
54
55 struct irqdesc irq_desc[NR_IRQS];
56
57 /*
58  * Dummy mask/unmask handler
59  */
60 void dummy_mask_unmask_irq(unsigned int irq)
61 {
62 }
63
64 void do_bad_IRQ(unsigned int irq, struct irqdesc *desc, struct pt_regs *regs)
65 {
66         irq_err_count += 1;
67         printk(KERN_ERR "IRQ: spurious interrupt %d\n", irq);
68 }
69
70 static struct irqchip bad_chip = {
71         .ack    = dummy_mask_unmask_irq,
72         .mask   = dummy_mask_unmask_irq,
73         .unmask = dummy_mask_unmask_irq,
74 };
75
76 static struct irqdesc bad_irq_desc = {
77         .chip   = &bad_chip,
78         .handle = do_bad_IRQ,
79         .depth  = 1,
80 };
81
82 /**
83  *      disable_irq - disable an irq and wait for completion
84  *      @irq: Interrupt to disable
85  *
86  *      Disable the selected interrupt line.  We do this lazily.
87  *
88  *      This function may be called from IRQ context.
89  */
90 void disable_irq(unsigned int irq)
91 {
92         struct irqdesc *desc = irq_desc + irq;
93         unsigned long flags;
94         spin_lock_irqsave(&irq_controller_lock, flags);
95         if (!desc->depth++)
96                 desc->enabled = 0;
97         spin_unlock_irqrestore(&irq_controller_lock, flags);
98 }
99
100 /**
101  *      enable_irq - enable interrupt handling on an irq
102  *      @irq: Interrupt to enable
103  *
104  *      Re-enables the processing of interrupts on this IRQ line.
105  *      Note that this may call the interrupt handler, so you may
106  *      get unexpected results if you hold IRQs disabled.
107  *
108  *      This function may be called from IRQ context.
109  */
110 void enable_irq(unsigned int irq)
111 {
112         struct irqdesc *desc = irq_desc + irq;
113         unsigned long flags;
114         int pending = 0;
115
116         spin_lock_irqsave(&irq_controller_lock, flags);
117         if (unlikely(!desc->depth)) {
118                 printk("enable_irq(%u) unbalanced from %p\n", irq,
119                         __builtin_return_address(0)); //FIXME bum addresses reported - why?
120         } else if (!--desc->depth) {
121                 desc->probing = 0;
122                 desc->enabled = 1;
123                 desc->chip->unmask(irq);
124                 pending = desc->pending;
125                 desc->pending = 0;
126                 /*
127                  * If the interrupt was waiting to be processed,
128                  * retrigger it.
129                  */
130                 if (pending)
131                         desc->chip->rerun(irq);
132         }
133         spin_unlock_irqrestore(&irq_controller_lock, flags);
134 }
135
136 int show_interrupts(struct seq_file *p, void *v)
137 {
138         int i = *(loff_t *) v;
139         struct irqaction * action;
140
141         if (i < NR_IRQS) {
142                 action = irq_desc[i].action;
143                 if (!action)
144                         continue;
145                 seq_printf(p, "%3d: %10u ", i, kstat_irqs(i));
146                 seq_printf(p, "  %s", action->name);
147                 for (action = action->next; action; action = action->next) {
148                         seq_printf(p, ", %s", action->name);
149                 }
150                 seq_putc(p, '\n');
151         } else if (i == NR_IRQS) {
152                 show_fiq_list(p, v);
153                 seq_printf(p, "Err: %10lu\n", irq_err_count);
154         }
155         return 0;
156 }
157
158 /*
159  * IRQ lock detection.
160  *
161  * Hopefully, this should get us out of a few locked situations.
162  * However, it may take a while for this to happen, since we need
163  * a large number if IRQs to appear in the same jiffie with the
164  * same instruction pointer (or within 2 instructions).
165  */
166 static int check_irq_lock(struct irqdesc *desc, int irq, struct pt_regs *regs)
167 {
168         unsigned long instr_ptr = instruction_pointer(regs);
169
170         if (desc->lck_jif == jiffies &&
171             desc->lck_pc >= instr_ptr && desc->lck_pc < instr_ptr + 8) {
172                 desc->lck_cnt += 1;
173
174                 if (desc->lck_cnt > MAX_IRQ_CNT) {
175                         printk(KERN_ERR "IRQ LOCK: IRQ%d is locking the system, disabled\n", irq);
176                         return 1;
177                 }
178         } else {
179                 desc->lck_cnt = 0;
180                 desc->lck_pc  = instruction_pointer(regs);
181                 desc->lck_jif = jiffies;
182         }
183         return 0;
184 }
185
186 static void
187 __do_irq(unsigned int irq, struct irqaction *action, struct pt_regs *regs)
188 {
189         unsigned int status;
190         int ret;
191
192         spin_unlock(&irq_controller_lock);
193         if (!(action->flags & SA_INTERRUPT))
194                 local_irq_enable();
195
196         status = 0;
197         do {
198                 ret = action->handler(irq, action->dev_id, regs);
199                 if (ret == IRQ_HANDLED)
200                         status |= action->flags;
201                 action = action->next;
202         } while (action);
203
204         if (status & SA_SAMPLE_RANDOM)
205                 add_interrupt_randomness(irq);
206
207         spin_lock_irq(&irq_controller_lock);
208 }
209
210 /*
211  * This is for software-decoded IRQs.  The caller is expected to
212  * handle the ack, clear, mask and unmask issues.
213  */
214 void
215 do_simple_IRQ(unsigned int irq, struct irqdesc *desc, struct pt_regs *regs)
216 {
217         struct irqaction *action;
218         const int cpu = smp_processor_id();
219
220         desc->triggered = 1;
221
222         kstat_cpu(cpu).irqs[irq]++;
223
224         action = desc->action;
225         if (action)
226                 __do_irq(irq, desc->action, regs);
227 }
228
229 /*
230  * Most edge-triggered IRQ implementations seem to take a broken
231  * approach to this.  Hence the complexity.
232  */
233 void
234 do_edge_IRQ(unsigned int irq, struct irqdesc *desc, struct pt_regs *regs)
235 {
236         const int cpu = smp_processor_id();
237
238         desc->triggered = 1;
239
240         /*
241          * If we're currently running this IRQ, or its disabled,
242          * we shouldn't process the IRQ.  Instead, turn on the
243          * hardware masks.
244          */
245         if (unlikely(desc->running || !desc->enabled))
246                 goto running;
247
248         /*
249          * Acknowledge and clear the IRQ, but don't mask it.
250          */
251         desc->chip->ack(irq);
252
253         /*
254          * Mark the IRQ currently in progress.
255          */
256         desc->running = 1;
257
258         kstat_cpu(cpu).irqs[irq]++;
259
260         do {
261                 struct irqaction *action;
262
263                 action = desc->action;
264                 if (!action)
265                         break;
266
267                 if (desc->pending && desc->enabled) {
268                         desc->pending = 0;
269                         desc->chip->unmask(irq);
270                 }
271
272                 __do_irq(irq, action, regs);
273         } while (desc->pending);
274
275         desc->running = 0;
276
277         /*
278          * If we were disabled or freed, shut down the handler.
279          */
280         if (likely(desc->action && !check_irq_lock(desc, irq, regs)))
281                 return;
282
283  running:
284         /*
285          * We got another IRQ while this one was masked or
286          * currently running.  Delay it.
287          */
288         desc->pending = 1;
289         desc->chip->mask(irq);
290         desc->chip->ack(irq);
291 }
292
293 /*
294  * Level-based IRQ handler.  Nice and simple.
295  */
296 void
297 do_level_IRQ(unsigned int irq, struct irqdesc *desc, struct pt_regs *regs)
298 {
299         struct irqaction *action;
300         const int cpu = smp_processor_id();
301
302         desc->triggered = 1;
303
304         /*
305          * Acknowledge, clear _AND_ disable the interrupt.
306          */
307         desc->chip->ack(irq);
308
309         if (likely(desc->enabled)) {
310                 kstat_cpu(cpu).irqs[irq]++;
311
312                 /*
313                  * Return with this interrupt masked if no action
314                  */
315                 action = desc->action;
316                 if (action) {
317                         __do_irq(irq, desc->action, regs);
318
319                         if (likely(desc->enabled &&
320                                    !check_irq_lock(desc, irq, regs)))
321                                 desc->chip->unmask(irq);
322                 }
323         }
324 }
325
326 /*
327  * do_IRQ handles all hardware IRQ's.  Decoded IRQs should not
328  * come via this function.  Instead, they should provide their
329  * own 'handler'
330  */
331 asmlinkage void asm_do_IRQ(int irq, struct pt_regs *regs)
332 {
333         struct irqdesc *desc = irq_desc + irq;
334
335         /*
336          * Some hardware gives randomly wrong interrupts.  Rather
337          * than crashing, do something sensible.
338          */
339         if (irq >= NR_IRQS)
340                 desc = &bad_irq_desc;
341
342         irq_enter();
343         spin_lock(&irq_controller_lock);
344         desc->handle(irq, desc, regs);
345         spin_unlock(&irq_controller_lock);
346         irq_exit();
347 }
348
349 void __set_irq_handler(unsigned int irq, irq_handler_t handle, int is_chained)
350 {
351         struct irqdesc *desc;
352         unsigned long flags;
353
354         if (irq >= NR_IRQS) {
355                 printk(KERN_ERR "Trying to install handler for IRQ%d\n", irq);
356                 return;
357         }
358
359         if (handle == NULL)
360                 handle = do_bad_IRQ;
361
362         desc = irq_desc + irq;
363
364         if (is_chained && desc->chip == &bad_chip)
365                 printk(KERN_WARNING "Trying to install chained handler for IRQ%d\n", irq);
366
367         spin_lock_irqsave(&irq_controller_lock, flags);
368         if (handle == do_bad_IRQ) {
369                 desc->chip->mask(irq);
370                 desc->chip->ack(irq);
371                 desc->depth = 1;
372                 desc->enabled = 0;
373         }
374         desc->handle = handle;
375         if (handle != do_bad_IRQ && is_chained) {
376                 desc->valid = 0;
377                 desc->probe_ok = 0;
378                 desc->depth = 0;
379                 desc->chip->unmask(irq);
380         }
381         spin_unlock_irqrestore(&irq_controller_lock, flags);
382 }
383
384 void set_irq_chip(unsigned int irq, struct irqchip *chip)
385 {
386         struct irqdesc *desc;
387         unsigned long flags;
388
389         if (irq >= NR_IRQS) {
390                 printk(KERN_ERR "Trying to install chip for IRQ%d\n", irq);
391                 return;
392         }
393
394         if (chip == NULL)
395                 chip = &bad_chip;
396
397         desc = irq_desc + irq;
398         spin_lock_irqsave(&irq_controller_lock, flags);
399         desc->chip = chip;
400         spin_unlock_irqrestore(&irq_controller_lock, flags);
401 }
402
403 int set_irq_type(unsigned int irq, unsigned int type)
404 {
405         struct irqdesc *desc;
406         unsigned long flags;
407         int ret = -ENXIO;
408
409         if (irq >= NR_IRQS) {
410                 printk(KERN_ERR "Trying to set irq type for IRQ%d\n", irq);
411                 return -ENODEV;
412         }
413
414         desc = irq_desc + irq;
415         if (desc->chip->type) {
416                 spin_lock_irqsave(&irq_controller_lock, flags);
417                 ret = desc->chip->type(irq, type);
418                 spin_unlock_irqrestore(&irq_controller_lock, flags);
419         }
420
421         return ret;
422 }
423
424 void set_irq_flags(unsigned int irq, unsigned int iflags)
425 {
426         struct irqdesc *desc;
427         unsigned long flags;
428
429         if (irq >= NR_IRQS) {
430                 printk(KERN_ERR "Trying to set irq flags for IRQ%d\n", irq);
431                 return;
432         }
433
434         desc = irq_desc + irq;
435         spin_lock_irqsave(&irq_controller_lock, flags);
436         desc->valid = (iflags & IRQF_VALID) != 0;
437         desc->probe_ok = (iflags & IRQF_PROBE) != 0;
438         desc->noautoenable = (iflags & IRQF_NOAUTOEN) != 0;
439         spin_unlock_irqrestore(&irq_controller_lock, flags);
440 }
441
442 int setup_irq(unsigned int irq, struct irqaction *new)
443 {
444         int shared = 0;
445         struct irqaction *old, **p;
446         unsigned long flags;
447         struct irqdesc *desc;
448
449         /*
450          * Some drivers like serial.c use request_irq() heavily,
451          * so we have to be careful not to interfere with a
452          * running system.
453          */
454         if (new->flags & SA_SAMPLE_RANDOM) {
455                 /*
456                  * This function might sleep, we want to call it first,
457                  * outside of the atomic block.
458                  * Yes, this might clear the entropy pool if the wrong
459                  * driver is attempted to be loaded, without actually
460                  * installing a new handler, but is this really a problem,
461                  * only the sysadmin is able to do this.
462                  */
463                 rand_initialize_irq(irq);
464         }
465
466         /*
467          * The following block of code has to be executed atomically
468          */
469         desc = irq_desc + irq;
470         spin_lock_irqsave(&irq_controller_lock, flags);
471         p = &desc->action;
472         if ((old = *p) != NULL) {
473                 /* Can't share interrupts unless both agree to */
474                 if (!(old->flags & new->flags & SA_SHIRQ)) {
475                         spin_unlock_irqrestore(&irq_controller_lock, flags);
476                         return -EBUSY;
477                 }
478
479                 /* add new interrupt at end of irq queue */
480                 do {
481                         p = &old->next;
482                         old = *p;
483                 } while (old);
484                 shared = 1;
485         }
486
487         *p = new;
488
489         if (!shared) {
490                 desc->probing = 0;
491                 desc->running = 0;
492                 desc->pending = 0;
493                 desc->depth = 1;
494                 if (!desc->noautoenable) {
495                         desc->depth = 0;
496                         desc->enabled = 1;
497                         desc->chip->unmask(irq);
498                 }
499         }
500
501         spin_unlock_irqrestore(&irq_controller_lock, flags);
502         return 0;
503 }
504
505 /**
506  *      request_irq - allocate an interrupt line
507  *      @irq: Interrupt line to allocate
508  *      @handler: Function to be called when the IRQ occurs
509  *      @irqflags: Interrupt type flags
510  *      @devname: An ascii name for the claiming device
511  *      @dev_id: A cookie passed back to the handler function
512  *
513  *      This call allocates interrupt resources and enables the
514  *      interrupt line and IRQ handling. From the point this
515  *      call is made your handler function may be invoked. Since
516  *      your handler function must clear any interrupt the board
517  *      raises, you must take care both to initialise your hardware
518  *      and to set up the interrupt handler in the right order.
519  *
520  *      Dev_id must be globally unique. Normally the address of the
521  *      device data structure is used as the cookie. Since the handler
522  *      receives this value it makes sense to use it.
523  *
524  *      If your interrupt is shared you must pass a non NULL dev_id
525  *      as this is required when freeing the interrupt.
526  *
527  *      Flags:
528  *
529  *      SA_SHIRQ                Interrupt is shared
530  *
531  *      SA_INTERRUPT            Disable local interrupts while processing
532  *
533  *      SA_SAMPLE_RANDOM        The interrupt can be used for entropy
534  *
535  */
536
537 //FIXME - handler used to return void - whats the significance of the change?
538 int request_irq(unsigned int irq, irqreturn_t (*handler)(int, void *, struct pt_regs *),
539                  unsigned long irq_flags, const char * devname, void *dev_id)
540 {
541         unsigned long retval;
542         struct irqaction *action;
543
544         if (irq >= NR_IRQS || !irq_desc[irq].valid || !handler ||
545             (irq_flags & SA_SHIRQ && !dev_id))
546                 return -EINVAL;
547
548         action = (struct irqaction *)kmalloc(sizeof(struct irqaction), GFP_KERNEL);
549         if (!action)
550                 return -ENOMEM;
551
552         action->handler = handler;
553         action->flags = irq_flags;
554         cpus_clear(action->mask);
555         action->name = devname;
556         action->next = NULL;
557         action->dev_id = dev_id;
558
559         retval = setup_irq(irq, action);
560
561         if (retval)
562                 kfree(action);
563         return retval;
564 }
565
566 EXPORT_SYMBOL(request_irq);
567
568 /**
569  *      free_irq - free an interrupt
570  *      @irq: Interrupt line to free
571  *      @dev_id: Device identity to free
572  *
573  *      Remove an interrupt handler. The handler is removed and if the
574  *      interrupt line is no longer in use by any driver it is disabled.
575  *      On a shared IRQ the caller must ensure the interrupt is disabled
576  *      on the card it drives before calling this function.
577  *
578  *      This function may be called from interrupt context.
579  */
580 void free_irq(unsigned int irq, void *dev_id)
581 {
582         struct irqaction * action, **p;
583         unsigned long flags;
584
585         if (irq >= NR_IRQS || !irq_desc[irq].valid) {
586                 printk(KERN_ERR "Trying to free IRQ%d\n",irq);
587 #ifdef CONFIG_DEBUG_ERRORS
588                 __backtrace();
589 #endif
590                 return;
591         }
592
593         spin_lock_irqsave(&irq_controller_lock, flags);
594         for (p = &irq_desc[irq].action; (action = *p) != NULL; p = &action->next) {
595                 if (action->dev_id != dev_id)
596                         continue;
597
598                 /* Found it - now free it */
599                 *p = action->next;
600                 kfree(action);
601                 goto out;
602         }
603         printk(KERN_ERR "Trying to free free IRQ%d\n",irq);
604 #ifdef CONFIG_DEBUG_ERRORS
605         __backtrace();
606 #endif
607 out:
608         spin_unlock_irqrestore(&irq_controller_lock, flags);
609 }
610
611 EXPORT_SYMBOL(free_irq);
612
613 /* Start the interrupt probing.  Unlike other architectures,
614  * we don't return a mask of interrupts from probe_irq_on,
615  * but return the number of interrupts enabled for the probe.
616  * The interrupts which have been enabled for probing is
617  * instead recorded in the irq_desc structure.
618  */
619 unsigned long probe_irq_on(void)
620 {
621         unsigned int i, irqs = 0;
622         unsigned long delay;
623
624         /*
625          * first snaffle up any unassigned but
626          * probe-able interrupts
627          */
628         spin_lock_irq(&irq_controller_lock);
629         for (i = 0; i < NR_IRQS; i++) {
630                 if (!irq_desc[i].probe_ok || irq_desc[i].action)
631                         continue;
632
633                 irq_desc[i].probing = 1;
634                 irq_desc[i].triggered = 0;
635                 if (irq_desc[i].chip->type)
636                         irq_desc[i].chip->type(i, IRQT_PROBE);
637                 irq_desc[i].chip->unmask(i);
638                 irqs += 1;
639         }
640         spin_unlock_irq(&irq_controller_lock);
641
642         /*
643          * wait for spurious interrupts to mask themselves out again
644          */
645         for (delay = jiffies + HZ/10; time_before(jiffies, delay); )
646                 /* min 100ms delay */;
647
648         /*
649          * now filter out any obviously spurious interrupts
650          */
651         spin_lock_irq(&irq_controller_lock);
652         for (i = 0; i < NR_IRQS; i++) {
653                 if (irq_desc[i].probing && irq_desc[i].triggered) {
654                         irq_desc[i].probing = 0;
655                         irqs -= 1;
656                 }
657         }
658         spin_unlock_irq(&irq_controller_lock);
659
660         return irqs;
661 }
662
663 EXPORT_SYMBOL(probe_irq_on);
664
665 /*
666  * Possible return values:
667  *  >= 0 - interrupt number
668  *    -1 - no interrupt/many interrupts
669  */
670 int probe_irq_off(unsigned long irqs)
671 {
672         unsigned int i;
673         int irq_found = NO_IRQ;
674
675         /*
676          * look at the interrupts, and find exactly one
677          * that we were probing has been triggered
678          */
679         spin_lock_irq(&irq_controller_lock);
680         for (i = 0; i < NR_IRQS; i++) {
681                 if (irq_desc[i].probing &&
682                     irq_desc[i].triggered) {
683                         if (irq_found != NO_IRQ) {
684                                 irq_found = NO_IRQ;
685                                 goto out;
686                         }
687                         irq_found = i;
688                 }
689         }
690
691         if (irq_found == -1)
692                 irq_found = NO_IRQ;
693 out:
694         spin_unlock_irq(&irq_controller_lock);
695
696         return irq_found;
697 }
698
699 EXPORT_SYMBOL(probe_irq_off);
700
701 void __init init_irq_proc(void)
702 {
703 }
704
705 void __init init_IRQ(void)
706 {
707         struct irqdesc *desc;
708         extern void init_dma(void);
709         int irq;
710
711         for (irq = 0, desc = irq_desc; irq < NR_IRQS; irq++, desc++)
712                 *desc = bad_irq_desc;
713
714         arc_init_irq();
715         init_dma();
716 }