2 * linux/arch/x86_64/kernel/irq.c
4 * Copyright (C) 1992, 1998 Linus Torvalds, Ingo Molnar
6 * This file contains the code used by various IRQ handling routines:
7 * asking for different IRQ's should be done through these routines
8 * instead of just grabbing them. Thus setups with different IRQ numbers
9 * shouldn't result in any weird surprises, and installing new handlers
14 * (mostly architecture independent, will move to kernel/irq.c in 2.5.)
16 * IRQs are in fact implemented a bit like signal handlers for the kernel.
17 * Naturally it's not a 1:1 relation, but there are similarities.
20 #include <linux/config.h>
21 #include <linux/errno.h>
22 #include <linux/module.h>
23 #include <linux/signal.h>
24 #include <linux/sched.h>
25 #include <linux/ioport.h>
26 #include <linux/interrupt.h>
27 #include <linux/timex.h>
28 #include <linux/slab.h>
29 #include <linux/random.h>
30 #include <linux/smp_lock.h>
31 #include <linux/init.h>
32 #include <linux/kernel_stat.h>
33 #include <linux/irq.h>
34 #include <linux/proc_fs.h>
35 #include <linux/seq_file.h>
37 #include <asm/atomic.h>
40 #include <asm/system.h>
41 #include <asm/bitops.h>
42 #include <asm/uaccess.h>
43 #include <asm/pgalloc.h>
44 #include <asm/delay.h>
51 * Linux has a controller-independent x86 interrupt architecture.
52 * every controller has a 'controller-template', that is used
53 * by the main code to do the right thing. Each driver-visible
54 * interrupt source is transparently wired to the appropriate
55 * controller. Thus drivers need not be aware of the
56 * interrupt-controller.
58 * Various interrupt controllers we handle: 8259 PIC, SMP IO-APIC,
59 * PIIX4's internal 8259 PIC and SGI's Visual Workstation Cobalt (IO-)APIC.
60 * (IO-APICs assumed to be messaging to Pentium local-APICs)
62 * the code is designed to be easily extended with new/different
63 * interrupt controllers, without having to do assembly magic.
67 * Controller mappings for all interrupt sources:
69 irq_desc_t irq_desc[NR_IRQS] __cacheline_aligned = {
71 .handler = &no_irq_type,
72 .lock = SPIN_LOCK_UNLOCKED
76 static void register_irq_proc (unsigned int irq);
79 * Special irq handlers.
82 irqreturn_t no_action(int cpl, void *dev_id, struct pt_regs *regs) { return IRQ_NONE; }
85 * Generic no controller code
88 static void enable_none(unsigned int irq) { }
89 static unsigned int startup_none(unsigned int irq) { return 0; }
90 static void disable_none(unsigned int irq) { }
91 static void ack_none(unsigned int irq)
94 * 'what should we do if we get a hw irq event on an illegal vector'.
95 * each architecture has to answer this themselves, it doesn't deserve
96 * a generic callback i think.
99 printk("unexpected IRQ trap at vector %02x\n", irq);
100 #ifdef CONFIG_X86_LOCAL_APIC
102 * Currently unexpected vectors happen only on SMP and APIC.
103 * We _must_ ack these because every local APIC has only N
104 * irq slots per priority level, and a 'hanging, unacked' IRQ
105 * holds up an irq slot - in excessive cases (when multiple
106 * unexpected vectors occur) that might lock up the APIC
114 /* startup is the same as "enable", shutdown is same as "disable" */
115 #define shutdown_none disable_none
116 #define end_none enable_none
118 struct hw_interrupt_type no_irq_type = {
128 atomic_t irq_err_count;
129 #ifdef CONFIG_X86_IO_APIC
130 #ifdef APIC_MISMATCH_DEBUG
131 atomic_t irq_mis_count;
136 * Generic, controller-independent functions:
139 int show_interrupts(struct seq_file *p, void *v)
141 int i = *(loff_t *) v, j;
142 struct irqaction * action;
147 for (j=0; j<NR_CPUS; j++)
149 seq_printf(p, "CPU%d ",j);
154 spin_lock_irqsave(&irq_desc[i].lock, flags);
155 action = irq_desc[i].action;
158 seq_printf(p, "%3d: ",i);
160 seq_printf(p, "%10u ", kstat_irqs(i));
162 for (j=0; j<NR_CPUS; j++)
164 seq_printf(p, "%10u ",
165 kstat_cpu(j).irqs[i]);
167 seq_printf(p, " %14s", irq_desc[i].handler->typename);
169 seq_printf(p, " %s", action->name);
170 for (action=action->next; action; action = action->next)
171 seq_printf(p, ", %s", action->name);
174 spin_unlock_irqrestore(&irq_desc[i].lock, flags);
175 } else if (i == NR_IRQS) {
176 seq_printf(p, "NMI: ");
177 for (j = 0; j < NR_CPUS; j++)
179 seq_printf(p, "%10u ", cpu_pda[j].__nmi_count);
181 #ifdef CONFIG_X86_LOCAL_APIC
182 seq_printf(p, "LOC: ");
183 for (j = 0; j < NR_CPUS; j++)
185 seq_printf(p, "%10u ", cpu_pda[j].apic_timer_irqs);
188 seq_printf(p, "ERR: %10u\n", atomic_read(&irq_err_count));
189 #ifdef CONFIG_X86_IO_APIC
190 #ifdef APIC_MISMATCH_DEBUG
191 seq_printf(p, "MIS: %10u\n", atomic_read(&irq_mis_count));
199 inline void synchronize_irq(unsigned int irq)
201 while (irq_desc[irq].status & IRQ_INPROGRESS)
207 * This should really return information about whether
208 * we should do bottom half handling etc. Right now we
209 * end up _always_ checking the bottom half, which is a
210 * waste of time and is not what some drivers would
213 int handle_IRQ_event(unsigned int irq, struct pt_regs * regs, struct irqaction * action)
215 int status = 1; /* Force the "do bottom halves" bit */
218 if (!(action->flags & SA_INTERRUPT))
222 ret = action->handler(irq, action->dev_id, regs);
223 if (ret == IRQ_HANDLED)
224 status |= action->flags;
225 action = action->next;
227 if (status & SA_SAMPLE_RANDOM)
228 add_interrupt_randomness(irq);
235 * Generic enable/disable code: this just calls
236 * down into the PIC-specific version for the actual
237 * hardware disable after having gotten the irq
242 * disable_irq_nosync - disable an irq without waiting
243 * @irq: Interrupt to disable
245 * Disable the selected interrupt line. Disables and Enables are
247 * Unlike disable_irq(), this function does not ensure existing
248 * instances of the IRQ handler have completed before returning.
250 * This function must not be called from IRQ context.
253 inline void disable_irq_nosync(unsigned int irq)
255 irq_desc_t *desc = irq_desc + irq;
258 spin_lock_irqsave(&desc->lock, flags);
259 if (!desc->depth++) {
260 desc->status |= IRQ_DISABLED;
261 desc->handler->disable(irq);
263 spin_unlock_irqrestore(&desc->lock, flags);
267 * disable_irq - disable an irq and wait for completion
268 * @irq: Interrupt to disable
270 * Disable the selected interrupt line. Enables and Disables are
272 * This function waits for any pending IRQ handlers for this interrupt
273 * to complete before returning. If you use this function while
274 * holding a resource the IRQ handler may need you will deadlock.
276 * This function may be called - with care - from IRQ context.
279 void disable_irq(unsigned int irq)
281 disable_irq_nosync(irq);
282 synchronize_irq(irq);
286 * enable_irq - enable handling of an irq
287 * @irq: Interrupt to enable
289 * Undoes the effect of one call to disable_irq(). If this
290 * matches the last disable, processing of interrupts on this
291 * IRQ line is re-enabled.
293 * This function may be called from IRQ context.
296 void enable_irq(unsigned int irq)
298 irq_desc_t *desc = irq_desc + irq;
301 spin_lock_irqsave(&desc->lock, flags);
302 switch (desc->depth) {
304 unsigned int status = desc->status & ~IRQ_DISABLED;
305 desc->status = status;
306 if ((status & (IRQ_PENDING | IRQ_REPLAY)) == IRQ_PENDING) {
307 desc->status = status | IRQ_REPLAY;
308 hw_resend_irq(desc->handler,irq);
310 desc->handler->enable(irq);
317 printk("enable_irq(%u) unbalanced from %p\n", irq,
318 __builtin_return_address(0));
320 spin_unlock_irqrestore(&desc->lock, flags);
324 * do_IRQ handles all normal device IRQ's (the special
325 * SMP cross-CPU interrupts have their own specific
328 asmlinkage unsigned int do_IRQ(struct pt_regs *regs)
331 * We ack quickly, we don't want the irq controller
332 * thinking we're snobs just because some other CPU has
333 * disabled global interrupts (we have already done the
334 * INT_ACK cycles, it's too late to try to pretend to the
335 * controller that we aren't taking the interrupt).
337 * 0 return value means that this irq is already being
338 * handled by some other CPU. (or is disabled)
340 unsigned irq = regs->orig_rax & 0xff; /* high bits used in ret_from_ code */
341 int cpu = smp_processor_id();
342 irq_desc_t *desc = irq_desc + irq;
343 struct irqaction * action;
346 if (irq > 256) BUG();
349 kstat_cpu(cpu).irqs[irq]++;
350 spin_lock(&desc->lock);
351 desc->handler->ack(irq);
353 REPLAY is when Linux resends an IRQ that was dropped earlier
354 WAITING is used by probe to mark irqs that are being tested
356 status = desc->status & ~(IRQ_REPLAY | IRQ_WAITING);
357 status |= IRQ_PENDING; /* we _want_ to handle it */
360 * If the IRQ is disabled for whatever reason, we cannot
361 * use the action we have.
364 if (likely(!(status & (IRQ_DISABLED | IRQ_INPROGRESS)))) {
365 action = desc->action;
366 status &= ~IRQ_PENDING; /* we commit to handling */
367 status |= IRQ_INPROGRESS; /* we are handling it */
369 desc->status = status;
372 * If there is no IRQ handler or it was disabled, exit early.
373 Since we set PENDING, if another processor is handling
374 a different instance of this same irq, the other processor
375 will take care of it.
377 if (unlikely(!action))
381 * Edge triggered interrupts need to remember
383 * This applies to any hw interrupts that allow a second
384 * instance of the same irq to arrive while we are in do_IRQ
385 * or in the handler. But the code here only handles the _second_
386 * instance of the irq, not the third or fourth. So it is mostly
387 * useful for irq hardware that does not mask cleanly in an
391 spin_unlock(&desc->lock);
392 handle_IRQ_event(irq, regs, action);
393 spin_lock(&desc->lock);
395 if (unlikely(!(desc->status & IRQ_PENDING)))
397 desc->status &= ~IRQ_PENDING;
399 desc->status &= ~IRQ_INPROGRESS;
402 * The ->end() handler has to deal with interrupts which got
403 * disabled while the handler was running.
405 if (irq > 256) BUG();
406 desc->handler->end(irq);
407 spin_unlock(&desc->lock);
413 int can_request_irq(unsigned int irq, unsigned long irqflags)
415 struct irqaction *action;
419 action = irq_desc[irq].action;
421 if (irqflags & action->flags & SA_SHIRQ)
428 * request_irq - allocate an interrupt line
429 * @irq: Interrupt line to allocate
430 * @handler: Function to be called when the IRQ occurs
431 * @irqflags: Interrupt type flags
432 * @devname: An ascii name for the claiming device
433 * @dev_id: A cookie passed back to the handler function
435 * This call allocates interrupt resources and enables the
436 * interrupt line and IRQ handling. From the point this
437 * call is made your handler function may be invoked. Since
438 * your handler function must clear any interrupt the board
439 * raises, you must take care both to initialise your hardware
440 * and to set up the interrupt handler in the right order.
442 * Dev_id must be globally unique. Normally the address of the
443 * device data structure is used as the cookie. Since the handler
444 * receives this value it makes sense to use it.
446 * If your interrupt is shared you must pass a non NULL dev_id
447 * as this is required when freeing the interrupt.
451 * SA_SHIRQ Interrupt is shared
453 * SA_INTERRUPT Disable local interrupts while processing
455 * SA_SAMPLE_RANDOM The interrupt can be used for entropy
459 int request_irq(unsigned int irq,
460 irqreturn_t (*handler)(int, void *, struct pt_regs *),
461 unsigned long irqflags,
462 const char * devname,
466 struct irqaction * action;
470 * Sanity-check: shared interrupts should REALLY pass in
471 * a real dev-ID, otherwise we'll have trouble later trying
472 * to figure out which interrupt is which (messes up the
473 * interrupt freeing logic etc).
475 if (irqflags & SA_SHIRQ) {
477 printk("Bad boy: %s (at 0x%x) called us without a dev_id!\n", devname, (&irq)[-1]);
486 action = (struct irqaction *)
487 kmalloc(sizeof(struct irqaction), GFP_ATOMIC);
491 action->handler = handler;
492 action->flags = irqflags;
493 cpus_clear(action->mask);
494 action->name = devname;
496 action->dev_id = dev_id;
498 retval = setup_irq(irq, action);
504 EXPORT_SYMBOL(request_irq);
507 * free_irq - free an interrupt
508 * @irq: Interrupt line to free
509 * @dev_id: Device identity to free
511 * Remove an interrupt handler. The handler is removed and if the
512 * interrupt line is no longer in use by any driver it is disabled.
513 * On a shared IRQ the caller must ensure the interrupt is disabled
514 * on the card it drives before calling this function. The function
515 * does not return until any executing interrupts for this IRQ
518 * This function may be called from interrupt context.
520 * Bugs: Attempting to free an irq in a handler for the same irq hangs
524 void free_irq(unsigned int irq, void *dev_id)
527 struct irqaction **p;
533 desc = irq_desc + irq;
534 spin_lock_irqsave(&desc->lock,flags);
537 struct irqaction * action = *p;
539 struct irqaction **pp = p;
541 if (action->dev_id != dev_id)
544 /* Found it - now remove it from the list of entries */
547 desc->status |= IRQ_DISABLED;
548 desc->handler->shutdown(irq);
550 spin_unlock_irqrestore(&desc->lock,flags);
552 synchronize_irq(irq);
556 printk("Trying to free free IRQ%d\n",irq);
557 spin_unlock_irqrestore(&desc->lock,flags);
562 EXPORT_SYMBOL(free_irq);
565 * IRQ autodetection code..
567 * This depends on the fact that any interrupt that
568 * comes in on to an unassigned handler will get stuck
569 * with "IRQ_WAITING" cleared and the interrupt
573 static DECLARE_MUTEX(probe_sem);
576 * probe_irq_on - begin an interrupt autodetect
578 * Commence probing for an interrupt. The interrupts are scanned
579 * and a mask of potential interrupt lines is returned.
583 unsigned long probe_irq_on(void)
592 * something may have generated an irq long ago and we want to
593 * flush such a longstanding irq before considering it as spurious.
595 for (i = NR_IRQS-1; i > 0; i--) {
598 spin_lock_irq(&desc->lock);
599 if (!irq_desc[i].action)
600 irq_desc[i].handler->startup(i);
601 spin_unlock_irq(&desc->lock);
604 /* Wait for longstanding interrupts to trigger. */
605 for (delay = jiffies + HZ/50; time_after(delay, jiffies); )
606 /* about 20ms delay */ barrier();
609 * enable any unassigned irqs
610 * (we must startup again here because if a longstanding irq
611 * happened in the previous stage, it may have masked itself)
613 for (i = NR_IRQS-1; i > 0; i--) {
616 spin_lock_irq(&desc->lock);
618 desc->status |= IRQ_AUTODETECT | IRQ_WAITING;
619 if (desc->handler->startup(i))
620 desc->status |= IRQ_PENDING;
622 spin_unlock_irq(&desc->lock);
626 * Wait for spurious interrupts to trigger
628 for (delay = jiffies + HZ/10; time_after(delay, jiffies); )
629 /* about 100ms delay */ barrier();
632 * Now filter out any obviously spurious interrupts
635 for (i = 0; i < NR_IRQS; i++) {
636 irq_desc_t *desc = irq_desc + i;
639 spin_lock_irq(&desc->lock);
640 status = desc->status;
642 if (status & IRQ_AUTODETECT) {
643 /* It triggered already - consider it spurious. */
644 if (!(status & IRQ_WAITING)) {
645 desc->status = status & ~IRQ_AUTODETECT;
646 desc->handler->shutdown(i);
651 spin_unlock_irq(&desc->lock);
657 EXPORT_SYMBOL(probe_irq_on);
660 * Return a mask of triggered interrupts (this
661 * can handle only legacy ISA interrupts).
665 * probe_irq_mask - scan a bitmap of interrupt lines
666 * @val: mask of interrupts to consider
668 * Scan the ISA bus interrupt lines and return a bitmap of
669 * active interrupts. The interrupt probe logic state is then
670 * returned to its previous value.
672 * Note: we need to scan all the irq's even though we will
673 * only return ISA irq numbers - just so that we reset them
674 * all to a known state.
676 unsigned int probe_irq_mask(unsigned long val)
682 for (i = 0; i < NR_IRQS; i++) {
683 irq_desc_t *desc = irq_desc + i;
686 spin_lock_irq(&desc->lock);
687 status = desc->status;
689 if (status & IRQ_AUTODETECT) {
690 if (i < 16 && !(status & IRQ_WAITING))
693 desc->status = status & ~IRQ_AUTODETECT;
694 desc->handler->shutdown(i);
696 spin_unlock_irq(&desc->lock);
704 * Return the one interrupt that triggered (this can
705 * handle any interrupt source).
709 * probe_irq_off - end an interrupt autodetect
710 * @val: mask of potential interrupts (unused)
712 * Scans the unused interrupt lines and returns the line which
713 * appears to have triggered the interrupt. If no interrupt was
714 * found then zero is returned. If more than one interrupt is
715 * found then minus the first candidate is returned to indicate
718 * The interrupt probe logic state is returned to its previous
721 * BUGS: When used in a module (which arguably shouldn't happen)
722 * nothing prevents two IRQ probe callers from overlapping. The
723 * results of this are non-optimal.
726 int probe_irq_off(unsigned long val)
728 int i, irq_found, nr_irqs;
732 for (i = 0; i < NR_IRQS; i++) {
733 irq_desc_t *desc = irq_desc + i;
736 spin_lock_irq(&desc->lock);
737 status = desc->status;
739 if (status & IRQ_AUTODETECT) {
740 if (!(status & IRQ_WAITING)) {
745 desc->status = status & ~IRQ_AUTODETECT;
746 desc->handler->shutdown(i);
748 spin_unlock_irq(&desc->lock);
753 irq_found = -irq_found;
757 EXPORT_SYMBOL(probe_irq_off);
759 /* this was setup_x86_irq but it seems pretty generic */
760 int setup_irq(unsigned int irq, struct irqaction * new)
764 struct irqaction *old, **p;
765 irq_desc_t *desc = irq_desc + irq;
767 if (desc->handler == &no_irq_type)
771 * Some drivers like serial.c use request_irq() heavily,
772 * so we have to be careful not to interfere with a
775 if (new->flags & SA_SAMPLE_RANDOM) {
777 * This function might sleep, we want to call it first,
778 * outside of the atomic block.
779 * Yes, this might clear the entropy pool if the wrong
780 * driver is attempted to be loaded, without actually
781 * installing a new handler, but is this really a problem,
782 * only the sysadmin is able to do this.
784 rand_initialize_irq(irq);
788 * The following block of code has to be executed atomically
790 spin_lock_irqsave(&desc->lock,flags);
792 if ((old = *p) != NULL) {
793 /* Can't share interrupts unless both agree to */
794 if (!(old->flags & new->flags & SA_SHIRQ)) {
795 spin_unlock_irqrestore(&desc->lock,flags);
799 /* add new interrupt at end of irq queue */
811 desc->status &= ~(IRQ_DISABLED | IRQ_AUTODETECT | IRQ_WAITING);
812 desc->handler->startup(irq);
814 spin_unlock_irqrestore(&desc->lock,flags);
816 register_irq_proc(irq);
820 static struct proc_dir_entry * root_irq_dir;
821 static struct proc_dir_entry * irq_dir [NR_IRQS];
825 static struct proc_dir_entry * smp_affinity_entry [NR_IRQS];
827 static cpumask_t irq_affinity [NR_IRQS] = { [0 ... NR_IRQS-1] = CPU_MASK_ALL };
828 static int irq_affinity_read_proc (char *page, char **start, off_t off,
829 int count, int *eof, void *data)
831 int len = cpumask_scnprintf(page, count, irq_affinity[(long)data]);
834 len += sprintf(page + len, "\n");
840 static int irq_affinity_write_proc (struct file *file,
841 const char __user *buffer,
842 unsigned long count, void *data)
844 int irq = (long) data, full_count = count, err;
845 cpumask_t tmp, new_value;
847 if (!irq_desc[irq].handler->set_affinity || no_irq_affinity)
850 err = cpumask_parse(buffer, count, new_value);
853 * Do not allow disabling IRQs completely - it's a too easy
854 * way to make the system unusable accidentally :-) At least
855 * one online CPU still has to be targeted.
857 cpus_and(tmp, new_value, cpu_online_map);
861 irq_affinity[irq] = new_value;
862 irq_desc[irq].handler->set_affinity(irq, new_value);
869 #define MAX_NAMELEN 10
871 static void register_irq_proc (unsigned int irq)
873 char name [MAX_NAMELEN];
875 if (!root_irq_dir || (irq_desc[irq].handler == &no_irq_type) ||
879 memset(name, 0, MAX_NAMELEN);
880 sprintf(name, "%d", irq);
882 /* create /proc/irq/1234 */
883 irq_dir[irq] = proc_mkdir(name, root_irq_dir);
887 struct proc_dir_entry *entry;
889 /* create /proc/irq/1234/smp_affinity */
890 entry = create_proc_entry("smp_affinity", 0600, irq_dir[irq]);
894 entry->data = (void *)(long)irq;
895 entry->read_proc = irq_affinity_read_proc;
896 entry->write_proc = irq_affinity_write_proc;
899 smp_affinity_entry[irq] = entry;
904 void init_irq_proc (void)
908 /* create /proc/irq */
909 root_irq_dir = proc_mkdir("irq", NULL);
911 /* create /proc/irq/prof_cpu_mask */
912 create_prof_cpu_mask(root_irq_dir);
915 * Create entries for all existing IRQs.
917 for (i = 0; i < NR_IRQS; i++)
918 register_irq_proc(i);