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Linux/arch/arm/kernel/irq.c

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  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  * This program is free software; you can redistribute it and/or modify
  8  * it under the terms of the GNU General Public License version 2 as
  9  * published by the Free Software Foundation.
 10  *
 11  *  This file contains the code used by various IRQ handling routines:
 12  *  asking for different IRQ's should be done through these routines
 13  *  instead of just grabbing them. Thus setups with different IRQ numbers
 14  *  shouldn't result in any weird surprises, and installing new handlers
 15  *  should be easier.
 16  *
 17  *  IRQ's are in fact implemented a bit like signal handlers for the kernel.
 18  *  Naturally it's not a 1:1 relation, but there are similarities.
 19  */
 20 #include <linux/config.h>
 21 #include <linux/ptrace.h>
 22 #include <linux/kernel_stat.h>
 23 #include <linux/signal.h>
 24 #include <linux/sched.h>
 25 #include <linux/ioport.h>
 26 #include <linux/interrupt.h>
 27 #include <linux/slab.h>
 28 #include <linux/random.h>
 29 #include <linux/smp.h>
 30 #include <linux/list.h>
 31 #include <linux/timer.h>
 32 #include <linux/init.h>
 33 
 34 #include <asm/irq.h>
 35 #include <asm/system.h>
 36 #include <asm/mach/irq.h>
 37 
 38 #include <asm/arch/irq.h>       /* pick up fixup_irq definition */
 39 
 40 /*
 41  * Maximum IRQ count.  Currently, this is arbitary.  However, it should
 42  * not be set too low to prevent false triggering.  Conversely, if it
 43  * is set too high, then you could miss a stuck IRQ.
 44  *
 45  * Maybe we ought to set a timer and re-enable the IRQ at a later time?
 46  */
 47 #define MAX_IRQ_CNT     100000
 48 
 49 static volatile unsigned long irq_err_count;
 50 static spinlock_t irq_controller_lock;
 51 static LIST_HEAD(irq_pending);
 52 
 53 struct irqdesc irq_desc[NR_IRQS];
 54 void (*init_arch_irq)(void) __initdata = NULL;
 55 
 56 /*
 57  * Dummy mask/unmask handler
 58  */
 59 static void dummy_mask_unmask_irq(unsigned int irq)
 60 {
 61 }
 62 
 63 /*
 64  * No architecture-specific irq_finish function defined in arm/arch/irq.h.
 65  */
 66 #ifndef irq_finish
 67 #define irq_finish(irq) do { } while (0)
 68 #endif
 69 
 70 /**
 71  *      disable_irq - disable an irq and wait for completion
 72  *      @irq: Interrupt to disable
 73  *
 74  *      Disable the selected interrupt line.  We do this lazily.
 75  *
 76  *      This function may be called from IRQ context.
 77  */
 78 void disable_irq(unsigned int irq)
 79 {
 80         struct irqdesc *desc = irq_desc + irq;
 81         unsigned long flags;
 82 
 83         spin_lock_irqsave(&irq_controller_lock, flags);
 84         if (!desc->disable_depth++) {
 85 #ifndef CONFIG_CPU_SA1100
 86                 desc->mask(irq);
 87 #endif
 88         }
 89         spin_unlock_irqrestore(&irq_controller_lock, flags);
 90 }
 91 
 92 /**
 93  *      enable_irq - enable interrupt handling on an irq
 94  *      @irq: Interrupt to enable
 95  *
 96  *      Re-enables the processing of interrupts on this IRQ line.
 97  *      Note that this may call the interrupt handler, so you may
 98  *      get unexpected results if you hold IRQs disabled.
 99  *
100  *      This function may be called from IRQ context.
101  */
102 void enable_irq(unsigned int irq)
103 {
104         struct irqdesc *desc = irq_desc + irq;
105         unsigned long flags;
106 
107         spin_lock_irqsave(&irq_controller_lock, flags);
108         if (!desc->disable_depth) {
109                 printk("enable_irq(%u) unbalanced from %p\n", irq,
110                         __builtin_return_address(0));
111         } else if (!--desc->disable_depth) {
112                 desc->probing = 0;
113                 desc->unmask(irq);
114 
115                 /*
116                  * If the interrupt is waiting to be processed,
117                  * try to re-run it.  We can't directly run it
118                  * from here since the caller might be in an
119                  * interrupt-protected region.
120                  */
121                 if (desc->pending) {
122                         desc->pending = 0;
123                         if (list_empty(&desc->pend))
124                                 list_add(&desc->pend, &irq_pending);
125                 }
126         }
127         spin_unlock_irqrestore(&irq_controller_lock, flags);
128 }
129 
130 int get_irq_list(char *buf)
131 {
132         int i;
133         struct irqaction * action;
134         char *p = buf;
135 
136         for (i = 0 ; i < NR_IRQS ; i++) {
137                 action = irq_desc[i].action;
138                 if (!action)
139                         continue;
140                 p += sprintf(p, "%3d: %10u ", i, kstat_irqs(i));
141                 p += sprintf(p, "  %s", action->name);
142                 for (action = action->next; action; action = action->next) {
143                         p += sprintf(p, ", %s", action->name);
144                 }
145                 *p++ = '\n';
146         }
147 
148 #ifdef CONFIG_ARCH_ACORN
149         p += get_fiq_list(p);
150 #endif
151         p += sprintf(p, "Err: %10lu\n", irq_err_count);
152         return p - buf;
153 }
154 
155 /*
156  * IRQ lock detection.
157  *
158  * Hopefully, this should get us out of a few locked situations.
159  * However, it may take a while for this to happen, since we need
160  * a large number if IRQs to appear in the same jiffie with the
161  * same instruction pointer (or within 2 instructions).
162  */
163 static int check_irq_lock(struct irqdesc *desc, int irq, struct pt_regs *regs)
164 {
165         unsigned long instr_ptr = instruction_pointer(regs);
166 
167         if (desc->lck_jif == jiffies &&
168             desc->lck_pc >= instr_ptr && desc->lck_pc < instr_ptr + 8) {
169                 desc->lck_cnt += 1;
170 
171                 if (desc->lck_cnt > MAX_IRQ_CNT) {
172                         if (!desc->lck_warned++)
173                                 printk(KERN_ERR "IRQ LOCK: IRQ%d is locking the system, disabled\n", irq);
174                         mod_timer(&desc->lck_timer, jiffies + 10*HZ);
175                         return 1;
176                 }
177         } else {
178                 desc->lck_cnt = 0;
179                 desc->lck_pc  = instruction_pointer(regs);
180                 desc->lck_jif = jiffies;
181                 if (desc->lck_warned < 0)
182                         desc->lck_warned ++;
183         }
184         return 0;
185 }
186 
187 static void
188 __do_irq(unsigned int irq, struct irqaction *action, struct pt_regs *regs)
189 {
190         unsigned int status;
191 
192         spin_unlock(&irq_controller_lock);
193 
194         if (!(action->flags & SA_INTERRUPT))
195                 local_irq_enable();
196 
197         status = 0;
198         do {
199                 status |= action->flags;
200                 action->handler(irq, action->dev_id, regs);
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  * do_IRQ handles all normal device IRQ's
212  */
213 void do_IRQ(int irq, struct pt_regs * regs)
214 {
215         struct irqdesc *desc = irq_desc + irq;
216 
217         desc->triggered = 1;
218 
219         /*
220          * Acknowledge and clear the IRQ, but (if its
221          * a level-based IRQ, don't mask it)
222          */
223         desc->mask_ack(irq);
224 
225         /*
226          * If we're currently running this IRQ, or its disabled,
227          * we shouldn't process the IRQ.  Instead, turn on the
228          * hardware masks.
229          */
230         if (desc->running || desc->disable_depth)
231                 goto running;
232 
233         /*
234          * Mark the IRQ currently in progress.
235          */
236         desc->running = 1;
237 
238         kstat.irqs[smp_processor_id()][irq]++;
239 
240         do {
241                 struct irqaction *action;
242 
243                 action = desc->action;
244                 if (!action)
245                         break;
246 
247                 if (desc->pending && desc->disable_depth == 0) {
248                         desc->pending = 0;
249                         desc->unmask(irq);
250                 }
251 
252                 __do_irq(irq, action, regs);
253         } while (desc->pending && desc->disable_depth == 0);
254 
255         desc->running = 0;
256 
257         /*
258          * If we are disabled or freed, shut down the handler.
259          */
260         if (desc->action && !check_irq_lock(desc, irq, regs))
261                 desc->unmask(irq);
262         return;
263 
264  running:
265         /*
266          * We got another IRQ while this one was masked or
267          * currently running.  Delay it.
268          */
269         desc->pending = 1;
270 }
271 
272 static void do_pending_irqs(struct pt_regs *regs)
273 {
274         struct list_head head, *l, *n;
275 
276         do {
277                 struct irqdesc *desc;
278 
279                 /*
280                  * First, take the pending interrupts off the list.
281                  * The act of calling the handlers may add some IRQs
282                  * back onto the list.
283                  */
284                 head = irq_pending;
285                 INIT_LIST_HEAD(&irq_pending);
286                 head.next->prev = &head;
287                 head.prev->next = &head;
288 
289                 /*
290                  * Now run each entry.  We must delete it from our
291                  * list before calling the handler.
292                  */
293                 list_for_each_safe(l, n, &head) {
294                         desc = list_entry(l, struct irqdesc, pend);
295                         list_del_init(&desc->pend);
296                         do_IRQ(desc - irq_desc, regs);
297                 }
298 
299                 /*
300                  * The list must be empty.
301                  */
302                 BUG_ON(!list_empty(&head));
303         } while (!list_empty(&irq_pending));
304 }
305 
306 /*
307  * do_IRQ handles all hardware IRQ's.  Decoded IRQs should not
308  * come via this function.  Instead, they should provide their
309  * own 'handler'
310  */
311 asmlinkage void asm_do_IRQ(int irq, struct pt_regs *regs)
312 {
313         irq = fixup_irq(irq);
314 
315         /*
316          * Some hardware gives randomly wrong interrupts.  Rather
317          * than crashing, do something sensible.
318          */
319         if (irq < NR_IRQS) {
320                 int cpu = smp_processor_id();
321 
322                 irq_enter(cpu, irq);
323                 spin_lock(&irq_controller_lock);
324                 do_IRQ(irq, regs);
325 
326                 /*
327                  * Now re-run any pending interrupts.
328                  */
329                 if (!list_empty(&irq_pending))
330                         do_pending_irqs(regs);
331 
332                 spin_unlock(&irq_controller_lock);
333                 irq_exit(cpu, irq);
334 
335                 if (softirq_pending(cpu))
336                         do_softirq();
337 
338                 irq_finish(irq);
339                 return;
340         }
341 
342         irq_err_count += 1;
343         printk(KERN_ERR "IRQ: spurious interrupt %d\n", irq);
344 
345         irq_finish(irq);
346         return;
347 }
348 
349 static void irqlck_timeout(unsigned long _data)
350 {
351         struct irqdesc *desc = (struct irqdesc *)_data;
352 
353         spin_lock(&irq_controller_lock);
354 
355         del_timer(&desc->lck_timer);
356 
357         desc->lck_cnt = 0;
358         desc->lck_pc  = 0;
359         desc->lck_jif = 0;
360         desc->lck_warned = -10;
361 
362         if (desc->disable_depth == 0)
363                 desc->unmask(desc - irq_desc);
364 
365         spin_unlock(&irq_controller_lock);
366 }
367 
368 #ifdef CONFIG_ARCH_ACORN
369 void do_ecard_IRQ(int irq, struct pt_regs *regs)
370 {
371         struct irqdesc * desc;
372         struct irqaction * action;
373         int cpu;
374 
375         desc = irq_desc + irq;
376 
377         cpu = smp_processor_id();
378         kstat.irqs[cpu][irq]++;
379         desc->triggered = 1;
380 
381         action = desc->action;
382 
383         if (action) {
384                 do {
385                         action->handler(irq, action->dev_id, regs);
386                         action = action->next;
387                 } while (action);
388         } else {
389                 spin_lock(&irq_controller_lock);
390                 desc->mask(irq);
391                 spin_unlock(&irq_controller_lock);
392         }
393 }
394 #endif
395 
396 int setup_arm_irq(int irq, struct irqaction * new)
397 {
398         int shared = 0;
399         struct irqaction *old, **p;
400         unsigned long flags;
401         struct irqdesc *desc;
402 
403         /*
404          * Some drivers like serial.c use request_irq() heavily,
405          * so we have to be careful not to interfere with a
406          * running system.
407          */
408         if (new->flags & SA_SAMPLE_RANDOM) {
409                 /*
410                  * This function might sleep, we want to call it first,
411                  * outside of the atomic block.
412                  * Yes, this might clear the entropy pool if the wrong
413                  * driver is attempted to be loaded, without actually
414                  * installing a new handler, but is this really a problem,
415                  * only the sysadmin is able to do this.
416                  */
417                 rand_initialize_irq(irq);
418         }
419 
420         /*
421          * The following block of code has to be executed atomically
422          */
423         desc = irq_desc + irq;
424         spin_lock_irqsave(&irq_controller_lock, flags);
425         p = &desc->action;
426         if ((old = *p) != NULL) {
427                 /* Can't share interrupts unless both agree to */
428                 if (!(old->flags & new->flags & SA_SHIRQ)) {
429                         spin_unlock_irqrestore(&irq_controller_lock, flags);
430                         return -EBUSY;
431                 }
432 
433                 /* add new interrupt at end of irq queue */
434                 do {
435                         p = &old->next;
436                         old = *p;
437                 } while (old);
438                 shared = 1;
439         }
440 
441         *p = new;
442 
443         if (!shared) {
444                 desc->probing = 0;
445                 desc->running = 0;
446                 desc->pending = 0;
447                 desc->disable_depth = 1;
448                 if (!desc->noautoenable) {
449                         desc->disable_depth = 0;
450                         desc->unmask(irq);
451                 }
452         }
453 
454         spin_unlock_irqrestore(&irq_controller_lock, flags);
455         return 0;
456 }
457 
458 /**
459  *      request_irq - allocate an interrupt line
460  *      @irq: Interrupt line to allocate
461  *      @handler: Function to be called when the IRQ occurs
462  *      @irqflags: Interrupt type flags
463  *      @devname: An ascii name for the claiming device
464  *      @dev_id: A cookie passed back to the handler function
465  *
466  *      This call allocates interrupt resources and enables the
467  *      interrupt line and IRQ handling. From the point this
468  *      call is made your handler function may be invoked. Since
469  *      your handler function must clear any interrupt the board
470  *      raises, you must take care both to initialise your hardware
471  *      and to set up the interrupt handler in the right order.
472  *
473  *      Dev_id must be globally unique. Normally the address of the
474  *      device data structure is used as the cookie. Since the handler
475  *      receives this value it makes sense to use it.
476  *
477  *      If your interrupt is shared you must pass a non NULL dev_id
478  *      as this is required when freeing the interrupt.
479  *
480  *      Flags:
481  *
482  *      SA_SHIRQ                Interrupt is shared
483  *
484  *      SA_INTERRUPT            Disable local interrupts while processing
485  *
486  *      SA_SAMPLE_RANDOM        The interrupt can be used for entropy
487  *
488  */
489 int request_irq(unsigned int irq, void (*handler)(int, void *, struct pt_regs *),
490                  unsigned long irq_flags, const char * devname, void *dev_id)
491 {
492         unsigned long retval;
493         struct irqaction *action;
494 
495         if (irq >= NR_IRQS || !irq_desc[irq].valid || !handler ||
496             (irq_flags & SA_SHIRQ && !dev_id))
497                 return -EINVAL;
498 
499         action = (struct irqaction *)kmalloc(sizeof(struct irqaction), GFP_KERNEL);
500         if (!action)
501                 return -ENOMEM;
502 
503         action->handler = handler;
504         action->flags = irq_flags;
505         action->mask = 0;
506         action->name = devname;
507         action->next = NULL;
508         action->dev_id = dev_id;
509 
510         retval = setup_arm_irq(irq, action);
511 
512         if (retval)
513                 kfree(action);
514         return retval;
515 }
516 
517 /**
518  *      free_irq - free an interrupt
519  *      @irq: Interrupt line to free
520  *      @dev_id: Device identity to free
521  *
522  *      Remove an interrupt handler. The handler is removed and if the
523  *      interrupt line is no longer in use by any driver it is disabled.
524  *      On a shared IRQ the caller must ensure the interrupt is disabled
525  *      on the card it drives before calling this function.
526  *
527  *      This function must not be called from interrupt context.
528  */
529 void free_irq(unsigned int irq, void *dev_id)
530 {
531         struct irqaction * action, **p;
532         unsigned long flags;
533 
534         if (irq >= NR_IRQS || !irq_desc[irq].valid) {
535                 printk(KERN_ERR "Trying to free IRQ%d\n",irq);
536 #ifdef CONFIG_DEBUG_ERRORS
537                 __backtrace();
538 #endif
539                 return;
540         }
541 
542         spin_lock_irqsave(&irq_controller_lock, flags);
543         for (p = &irq_desc[irq].action; (action = *p) != NULL; p = &action->next) {
544                 if (action->dev_id != dev_id)
545                         continue;
546 
547                 /* Found it - now free it */
548                 *p = action->next;
549                 kfree(action);
550                 goto out;
551         }
552         printk(KERN_ERR "Trying to free free IRQ%d\n",irq);
553 #ifdef CONFIG_DEBUG_ERRORS
554         __backtrace();
555 #endif
556 out:
557         spin_unlock_irqrestore(&irq_controller_lock, flags);
558 }
559 
560 static DECLARE_MUTEX(probe_sem);
561 
562 /* Start the interrupt probing.  Unlike other architectures,
563  * we don't return a mask of interrupts from probe_irq_on,
564  * but return the number of interrupts enabled for the probe.
565  * The interrupts which have been enabled for probing is
566  * instead recorded in the irq_desc structure.
567  */
568 unsigned long probe_irq_on(void)
569 {
570         unsigned int i, irqs = 0;
571         unsigned long delay;
572 
573         down(&probe_sem);
574 
575         /*
576          * first snaffle up any unassigned but
577          * probe-able interrupts
578          */
579         spin_lock_irq(&irq_controller_lock);
580         for (i = 0; i < NR_IRQS; i++) {
581                 if (!irq_desc[i].probe_ok || irq_desc[i].action)
582                         continue;
583 
584                 irq_desc[i].probing = 1;
585                 irq_desc[i].triggered = 0;
586                 irq_desc[i].unmask(i);
587                 irqs += 1;
588         }
589         spin_unlock_irq(&irq_controller_lock);
590 
591         /*
592          * wait for spurious interrupts to mask themselves out again
593          */
594         for (delay = jiffies + HZ/10; time_before(jiffies, delay); )
595                 /* min 100ms delay */;
596 
597         /*
598          * now filter out any obviously spurious interrupts
599          */
600         spin_lock_irq(&irq_controller_lock);
601         for (i = 0; i < NR_IRQS; i++) {
602                 if (irq_desc[i].probing && irq_desc[i].triggered) {
603                         irq_desc[i].probing = 0;
604                         irqs -= 1;
605                 }
606         }
607         spin_unlock_irq(&irq_controller_lock);
608 
609         return irqs;
610 }
611 
612 unsigned int probe_irq_mask(unsigned long irqs)
613 {
614         unsigned int mask = 0, i;
615 
616         spin_lock_irq(&irq_controller_lock);
617         for (i = 0; i < 16 && i < NR_IRQS; i++)
618                 if (irq_desc[i].probing && irq_desc[i].triggered)
619                         mask |= 1 << i;
620         spin_unlock_irq(&irq_controller_lock);
621 
622         up(&probe_sem);
623 
624         return mask;
625 }
626 
627 /*
628  * Possible return values:
629  *  >= 0 - interrupt number
630  *    -1 - no interrupt/many interrupts
631  */
632 int probe_irq_off(unsigned long irqs)
633 {
634         unsigned int i;
635         int irq_found = NO_IRQ;
636 
637         /*
638          * look at the interrupts, and find exactly one
639          * that we were probing has been triggered
640          */
641         spin_lock_irq(&irq_controller_lock);
642         for (i = 0; i < NR_IRQS; i++) {
643                 if (irq_desc[i].probing &&
644                     irq_desc[i].triggered) {
645                         if (irq_found != NO_IRQ) {
646                                 irq_found = NO_IRQ;
647                                 goto out;
648                         }
649                         irq_found = i;
650                 }
651         }
652 
653         if (irq_found == -1)
654                 irq_found = NO_IRQ;
655 out:
656         spin_unlock_irq(&irq_controller_lock);
657 
658         up(&probe_sem);
659 
660         return irq_found;
661 }
662 
663 void __init init_irq_proc(void)
664 {
665 }
666 
667 void __init init_IRQ(void)
668 {
669         extern void init_dma(void);
670         int irq;
671 
672         for (irq = 0; irq < NR_IRQS; irq++) {
673                 irq_desc[irq].disable_depth = 1;
674                 irq_desc[irq].probe_ok = 0;
675                 irq_desc[irq].valid    = 0;
676                 irq_desc[irq].noautoenable = 0;
677                 irq_desc[irq].mask_ack = dummy_mask_unmask_irq;
678                 irq_desc[irq].mask     = dummy_mask_unmask_irq;
679                 irq_desc[irq].unmask   = dummy_mask_unmask_irq;
680                 INIT_LIST_HEAD(&irq_desc[irq].pend);
681                 init_timer(&irq_desc[irq].lck_timer);
682                 irq_desc[irq].lck_timer.data = (unsigned long)&irq_desc[irq];
683                 irq_desc[irq].lck_timer.function = irqlck_timeout;
684         }
685 
686         init_arch_irq();
687         init_dma();
688 }
689 

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