arch/alpha/kernel/irq.c

   1 /*
   2  *      linux/arch/alpha/kernel/irq.c
   3  *
   4  *      Copyright (C) 1995 Linus Torvalds
   5  *
   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
  10  * should be easier.
  11  */
  12
  13 #include <linux/config.h>
  14 #include <linux/kernel.h>
  15 #include <linux/module.h>
  16 #include <linux/errno.h>
  17 #include <linux/kernel_stat.h>
  18 #include <linux/signal.h>
  19 #include <linux/sched.h>
  20 #include <linux/ptrace.h>
  21 #include <linux/interrupt.h>
  22 #include <linux/slab.h>
  23 #include <linux/random.h>
  24 #include <linux/init.h>
  25 #include <linux/irq.h>
  26 #include <linux/proc_fs.h>
  27 #include <linux/seq_file.h>
  28
  29 #include <asm/system.h>
  30 #include <asm/io.h>
  31 #include <asm/bitops.h>
  32 #include <asm/uaccess.h>
  33
  34 /*
  35  * Controller mappings for all interrupt sources:
  36  */
  37 irq_desc_t irq_desc[NR_IRQS] __cacheline_aligned = {
  38         [0 ... NR_IRQS-1] = {
  39                 .handler = &no_irq_type,
  40                 .lock = SPIN_LOCK_UNLOCKED
  41         }
  42 };
  43
  44 static void register_irq_proc(unsigned int irq);
  45
  46 volatile unsigned long irq_err_count;
  47
  48 /*
  49  * Special irq handlers.
  50  */
  51
  52 irqreturn_t no_action(int cpl, void *dev_id, struct pt_regs *regs)
  53 {
  54         return IRQ_NONE;
  55 }
  56
  57 /*
  58  * Generic no controller code
  59  */
  60
  61 static void no_irq_enable_disable(unsigned int irq) { }
  62 static unsigned int no_irq_startup(unsigned int irq) { return 0; }
  63
  64 static void
  65 no_irq_ack(unsigned int irq)
  66 {
  67         irq_err_count++;
  68         printk(KERN_CRIT "Unexpected IRQ trap at vector %u\n", irq);
  69 }
  70
  71 struct hw_interrupt_type no_irq_type = {
  72         .typename       = "none",
  73         .startup        = no_irq_startup,
  74         .shutdown       = no_irq_enable_disable,
  75         .enable         = no_irq_enable_disable,
  76         .disable        = no_irq_enable_disable,
  77         .ack            = no_irq_ack,
  78         .end            = no_irq_enable_disable,
  79 };
  80
  81 int
  82 handle_IRQ_event(unsigned int irq, struct pt_regs *regs,
  83                  struct irqaction *action)
  84 {
  85         int status = 1; /* Force the "do bottom halves" bit */
  86
  87         do {
  88                 if (!(action->flags & SA_INTERRUPT))
  89                         local_irq_enable();
  90                 else
  91                         local_irq_disable();
  92
  93                 status |= action->flags;
  94                 action->handler(irq, action->dev_id, regs);
  95                 action = action->next;
  96         } while (action);
  97         if (status & SA_SAMPLE_RANDOM)
  98                 add_interrupt_randomness(irq);
  99         local_irq_disable();
 100
 101         return status;
 102 }
 103
 104 /*
 105  * Generic enable/disable code: this just calls
 106  * down into the PIC-specific version for the actual
 107  * hardware disable after having gotten the irq
 108  * controller lock.
 109  */
 110 void inline
 111 disable_irq_nosync(unsigned int irq)
 112 {
 113         irq_desc_t *desc = irq_desc + irq;
 114         unsigned long flags;
 115
 116         spin_lock_irqsave(&desc->lock, flags);
 117         if (!desc->depth++) {
 118                 desc->status |= IRQ_DISABLED;
 119                 desc->handler->disable(irq);
 120         }
 121         spin_unlock_irqrestore(&desc->lock, flags);
 122 }
 123
 124 /*
 125  * Synchronous version of the above, making sure the IRQ is
 126  * no longer running on any other IRQ..
 127  */
 128 void
 129 disable_irq(unsigned int irq)
 130 {
 131         disable_irq_nosync(irq);
 132         synchronize_irq(irq);
 133 }
 134
 135 void
 136 enable_irq(unsigned int irq)
 137 {
 138         irq_desc_t *desc = irq_desc + irq;
 139         unsigned long flags;
 140
 141         spin_lock_irqsave(&desc->lock, flags);
 142         switch (desc->depth) {
 143         case 1: {
 144                 unsigned int status = desc->status & ~IRQ_DISABLED;
 145                 desc->status = status;
 146                 if ((status & (IRQ_PENDING | IRQ_REPLAY)) == IRQ_PENDING) {
 147                         desc->status = status | IRQ_REPLAY;
 148                         hw_resend_irq(desc->handler,irq);
 149                 }
 150                 desc->handler->enable(irq);
 151                 /* fall-through */
 152         }
 153         default:
 154                 desc->depth--;
 155                 break;
 156         case 0:
 157                 printk(KERN_ERR "enable_irq() unbalanced from %p\n",
 158                        __builtin_return_address(0));
 159         }
 160         spin_unlock_irqrestore(&desc->lock, flags);
 161 }
 162
 163 int
 164 setup_irq(unsigned int irq, struct irqaction * new)
 165 {
 166         int shared = 0;
 167         struct irqaction *old, **p;
 168         unsigned long flags;
 169         irq_desc_t *desc = irq_desc + irq;
 170
 171         if (desc->handler == &no_irq_type)
 172                 return -ENOSYS;
 173
 174         /*
 175          * Some drivers like serial.c use request_irq() heavily,
 176          * so we have to be careful not to interfere with a
 177          * running system.
 178          */
 179         if (new->flags & SA_SAMPLE_RANDOM) {
 180                 /*
 181                  * This function might sleep, we want to call it first,
 182                  * outside of the atomic block.
 183                  * Yes, this might clear the entropy pool if the wrong
 184                  * driver is attempted to be loaded, without actually
 185                  * installing a new handler, but is this really a problem,
 186                  * only the sysadmin is able to do this.
 187                  */
 188                 rand_initialize_irq(irq);
 189         }
 190
 191         /*
 192          * The following block of code has to be executed atomically
 193          */
 194         spin_lock_irqsave(&desc->lock,flags);
 195         p = &desc->action;
 196         if ((old = *p) != NULL) {
 197                 /* Can't share interrupts unless both agree to */
 198                 if (!(old->flags & new->flags & SA_SHIRQ)) {
 199                         spin_unlock_irqrestore(&desc->lock,flags);
 200                         return -EBUSY;
 201                 }
 202
 203                 /* add new interrupt at end of irq queue */
 204                 do {
 205                         p = &old->next;
 206                         old = *p;
 207                 } while (old);
 208                 shared = 1;
 209         }
 210
 211         *p = new;
 212
 213         if (!shared) {
 214                 desc->depth = 0;
 215                 desc->status &=
 216                     ~(IRQ_DISABLED|IRQ_AUTODETECT|IRQ_WAITING|IRQ_INPROGRESS);
 217                 desc->handler->startup(irq);
 218         }
 219         spin_unlock_irqrestore(&desc->lock,flags);
 220
 221         return 0;
 222 }
 223
 224 static struct proc_dir_entry * root_irq_dir;
 225 static struct proc_dir_entry * irq_dir[NR_IRQS];
 226
 227 #ifdef CONFIG_SMP
 228 static struct proc_dir_entry * smp_affinity_entry[NR_IRQS];
 229 static char irq_user_affinity[NR_IRQS];
 230 static unsigned long irq_affinity[NR_IRQS] = { [0 ... NR_IRQS-1] = ~0UL };
 231
 232 static void
 233 select_smp_affinity(int irq)
 234 {
 235         static int last_cpu;
 236         int cpu = last_cpu + 1;
 237
 238         if (! irq_desc[irq].handler->set_affinity || irq_user_affinity[irq])
 239                 return;
 240
 241         while (((cpu_present_mask >> cpu) & 1) == 0)
 242                 cpu = (cpu < (NR_CPUS-1) ? cpu + 1 : 0);
 243         last_cpu = cpu;
 244
 245         irq_affinity[irq] = 1UL << cpu;
 246         irq_desc[irq].handler->set_affinity(irq, 1UL << cpu);
 247 }
 248
 249 #define HEX_DIGITS 16
 250
 251 static int
 252 irq_affinity_read_proc (char *page, char **start, off_t off,
 253                         int count, int *eof, void *data)
 254 {
 255         int len = cpumask_scnprintf(page, count, irq_affinity[(long)data]);
 256         if (count - len < 2)
 257                 return -EINVAL;
 258         len += sprintf(page + len, "\n");
 259         return len;
 260 }
 261
 262 static unsigned int
 263 parse_hex_value (const char __user *buffer,
 264                  unsigned long count, unsigned long *ret)
 265 {
 266         unsigned char hexnum [HEX_DIGITS];
 267         unsigned long value;
 268         unsigned long i;
 269
 270         if (!count)
 271                 return -EINVAL;
 272         if (count > HEX_DIGITS)
 273                 count = HEX_DIGITS;
 274         if (copy_from_user(hexnum, buffer, count))
 275                 return -EFAULT;
 276
 277         /*
 278          * Parse the first 8 characters as a hex string, any non-hex char
 279          * is end-of-string. '00e1', 'e1', '00E1', 'E1' are all the same.
 280          */
 281         value = 0;
 282
 283         for (i = 0; i < count; i++) {
 284                 unsigned int c = hexnum[i];
 285
 286                 switch (c) {
 287                         case '0' ... '9': c -= '0'; break;
 288                         case 'a' ... 'f': c -= 'a'-10; break;
 289                         case 'A' ... 'F': c -= 'A'-10; break;
 290                 default:
 291                         goto out;
 292                 }
 293                 value = (value << 4) | c;
 294         }
 295 out:
 296         *ret = value;
 297         return 0;
 298 }
 299
 300 static int
 301 irq_affinity_write_proc(struct file *file, const char __user *buffer,
 302                         unsigned long count, void *data)
 303 {
 304         int irq = (long) data, full_count = count, err;
 305         unsigned long new_value;
 306
 307         if (!irq_desc[irq].handler->set_affinity)
 308                 return -EIO;
 309
 310         err = parse_hex_value(buffer, count, &new_value);
 311
 312         /* The special value 0 means release control of the
 313            affinity to kernel.  */
 314         if (new_value == 0) {
 315                 irq_user_affinity[irq] = 0;
 316                 select_smp_affinity(irq);
 317         }
 318         /* Do not allow disabling IRQs completely - it's a too easy
 319            way to make the system unusable accidentally :-) At least
 320            one online CPU still has to be targeted.  */
 321         else if (!(new_value & cpu_present_mask))
 322                 return -EINVAL;
 323         else {
 324                 irq_affinity[irq] = new_value;
 325                 irq_user_affinity[irq] = 1;
 326                 irq_desc[irq].handler->set_affinity(irq, new_value);
 327         }
 328
 329         return full_count;
 330 }
 331
 332 static int
 333 prof_cpu_mask_read_proc(char *page, char **start, off_t off,
 334                         int count, int *eof, void *data)
 335 {
 336         int len = cpumask_scnprintf(page, count, *(cpumask_t *)data);
 337         if (count - len < 2)
 338                 return -EINVAL;
 339         len += sprintf(page + len, "\n");
 340         return len;
 341 }
 342
 343 static int
 344 prof_cpu_mask_write_proc(struct file *file, const char __user *buffer,
 345                          unsigned long count, void *data)
 346 {
 347         unsigned long *mask = (unsigned long *) data, full_count = count, err;
 348         unsigned long new_value;
 349
 350         err = parse_hex_value(buffer, count, &new_value);
 351         if (err)
 352                 return err;
 353
 354         *mask = new_value;
 355         return full_count;
 356 }
 357 #endif /* CONFIG_SMP */
 358
 359 #define MAX_NAMELEN 10
 360
 361 static void
 362 register_irq_proc (unsigned int irq)
 363 {
 364         char name [MAX_NAMELEN];
 365
 366         if (!root_irq_dir || (irq_desc[irq].handler == &no_irq_type) ||
 367             irq_dir[irq])
 368                 return;
 369
 370         memset(name, 0, MAX_NAMELEN);
 371         sprintf(name, "%d", irq);
 372
 373         /* create /proc/irq/1234 */
 374         irq_dir[irq] = proc_mkdir(name, root_irq_dir);
 375
 376 #ifdef CONFIG_SMP
 377         if (irq_desc[irq].handler->set_affinity) {
 378                 struct proc_dir_entry *entry;
 379                 /* create /proc/irq/1234/smp_affinity */
 380                 entry = create_proc_entry("smp_affinity", 0600, irq_dir[irq]);
 381
 382                 if (entry) {
 383                         entry->nlink = 1;
 384                         entry->data = (void *)(long)irq;
 385                         entry->read_proc = irq_affinity_read_proc;
 386                         entry->write_proc = irq_affinity_write_proc;
 387                 }
 388
 389                 smp_affinity_entry[irq] = entry;
 390         }
 391 #endif
 392 }
 393
 394 unsigned long prof_cpu_mask = ~0UL;
 395
 396 void
 397 init_irq_proc (void)
 398 {
 399 #ifdef CONFIG_SMP
 400         struct proc_dir_entry *entry;
 401 #endif
 402         int i;
 403
 404         /* create /proc/irq */
 405         root_irq_dir = proc_mkdir("irq", 0);
 406
 407 #ifdef CONFIG_SMP
 408         /* create /proc/irq/prof_cpu_mask */
 409         entry = create_proc_entry("prof_cpu_mask", 0600, root_irq_dir);
 410
 411         entry->nlink = 1;
 412         entry->data = (void *)&prof_cpu_mask;
 413         entry->read_proc = prof_cpu_mask_read_proc;
 414         entry->write_proc = prof_cpu_mask_write_proc;
 415 #endif
 416
 417         /*
 418          * Create entries for all existing IRQs.
 419          */
 420         for (i = 0; i < ACTUAL_NR_IRQS; i++) {
 421                 if (irq_desc[i].handler == &no_irq_type)
 422                         continue;
 423                 register_irq_proc(i);
 424         }
 425 }
 426
 427 int
 428 request_irq(unsigned int irq, irqreturn_t (*handler)(int, void *, struct pt_regs *),
 429             unsigned long irqflags, const char * devname, void *dev_id)
 430 {
 431         int retval;
 432         struct irqaction * action;
 433
 434         if (irq >= ACTUAL_NR_IRQS)
 435                 return -EINVAL;
 436         if (!handler)
 437                 return -EINVAL;
 438
 439 #if 1
 440         /*
 441          * Sanity-check: shared interrupts should REALLY pass in
 442          * a real dev-ID, otherwise we'll have trouble later trying
 443          * to figure out which interrupt is which (messes up the
 444          * interrupt freeing logic etc).
 445          */
 446         if ((irqflags & SA_SHIRQ) && !dev_id) {
 447                 printk(KERN_ERR
 448                        "Bad boy: %s (at %p) called us without a dev_id!\n",
 449                        devname, __builtin_return_address(0));
 450         }
 451 #endif
 452
 453         action = (struct irqaction *)
 454                         kmalloc(sizeof(struct irqaction), GFP_KERNEL);
 455         if (!action)
 456                 return -ENOMEM;
 457
 458         action->handler = handler;
 459         action->flags = irqflags;
 460         action->mask = 0;
 461         action->name = devname;
 462         action->next = NULL;
 463         action->dev_id = dev_id;
 464
 465 #ifdef CONFIG_SMP
 466         select_smp_affinity(irq);
 467 #endif
 468
 469         retval = setup_irq(irq, action);
 470         if (retval)
 471                 kfree(action);
 472         return retval;
 473 }
 474
 475 EXPORT_SYMBOL(request_irq);
 476
 477 void
 478 free_irq(unsigned int irq, void *dev_id)
 479 {
 480         irq_desc_t *desc;
 481         struct irqaction **p;
 482         unsigned long flags;
 483
 484         if (irq >= ACTUAL_NR_IRQS) {
 485                 printk(KERN_CRIT "Trying to free IRQ%d\n", irq);
 486                 return;
 487         }
 488
 489         desc = irq_desc + irq;
 490         spin_lock_irqsave(&desc->lock,flags);
 491         p = &desc->action;
 492         for (;;) {
 493                 struct irqaction * action = *p;
 494                 if (action) {
 495                         struct irqaction **pp = p;
 496                         p = &action->next;
 497                         if (action->dev_id != dev_id)
 498                                 continue;
 499
 500                         /* Found - now remove it from the list of entries.  */
 501                         *pp = action->next;
 502                         if (!desc->action) {
 503                                 desc->status |= IRQ_DISABLED;
 504                                 desc->handler->shutdown(irq);
 505                         }
 506                         spin_unlock_irqrestore(&desc->lock,flags);
 507
 508 #ifdef CONFIG_SMP
 509                         /* Wait to make sure it's not being used on
 510                            another CPU.  */
 511                         while (desc->status & IRQ_INPROGRESS)
 512                                 barrier();
 513 #endif
 514                         kfree(action);
 515                         return;
 516                 }
 517                 printk(KERN_ERR "Trying to free free IRQ%d\n",irq);
 518                 spin_unlock_irqrestore(&desc->lock,flags);
 519                 return;
 520         }
 521 }
 522
 523 EXPORT_SYMBOL(free_irq);
 524
 525 int
 526 show_interrupts(struct seq_file *p, void *v)
 527 {
 528 #ifdef CONFIG_SMP
 529         int j;
 530 #endif
 531         int i = *(loff_t *) v;
 532         struct irqaction * action;
 533         unsigned long flags;
 534
 535 #ifdef CONFIG_SMP
 536         if (i == 0) {
 537                 seq_puts(p, "           ");
 538                 for (i = 0; i < NR_CPUS; i++)
 539                         if (cpu_online(i))
 540                                 seq_printf(p, "CPU%d       ", i);
 541                 seq_putc(p, '\n');
 542         }
 543 #endif
 544
 545         if (i < ACTUAL_NR_IRQS) {
 546                 spin_lock_irqsave(&irq_desc[i].lock, flags);
 547                 action = irq_desc[i].action;
 548                 if (!action)
 549                         goto unlock;
 550                 seq_printf(p, "%3d: ",i);
 551 #ifndef CONFIG_SMP
 552                 seq_printf(p, "%10u ", kstat_irqs(i));
 553 #else
 554                 for (j = 0; j < NR_CPUS; j++)
 555                         if (cpu_online(j))
 556                                 seq_printf(p, "%10u ", kstat_cpu(j).irqs[i]);
 557 #endif
 558                 seq_printf(p, " %14s", irq_desc[i].handler->typename);
 559                 seq_printf(p, "  %c%s",
 560                         (action->flags & SA_INTERRUPT)?'+':' ',
 561                         action->name);
 562
 563                 for (action=action->next; action; action = action->next) {
 564                         seq_printf(p, ", %c%s",
 565                                   (action->flags & SA_INTERRUPT)?'+':' ',
 566                                    action->name);
 567                 }
 568
 569                 seq_putc(p, '\n');
 570 unlock:
 571                 spin_unlock_irqrestore(&irq_desc[i].lock, flags);
 572         } else if (i == ACTUAL_NR_IRQS) {
 573 #ifdef CONFIG_SMP
 574                 seq_puts(p, "IPI: ");
 575                 for (i = 0; i < NR_CPUS; i++)
 576                         if (cpu_online(i))
 577                                 seq_printf(p, "%10lu ", cpu_data[i].ipi_count);
 578                 seq_putc(p, '\n');
 579 #endif
 580                 seq_printf(p, "ERR: %10lu\n", irq_err_count);
 581         }
 582         return 0;
 583 }
 584
 585
 586 /*
 587  * handle_irq handles all normal device IRQ's (the special
 588  * SMP cross-CPU interrupts have their own specific
 589  * handlers).
 590  */
 591
 592 #define MAX_ILLEGAL_IRQS 16
 593
 594 void
 595 handle_irq(int irq, struct pt_regs * regs)
 596 {
 597         /*
 598          * We ack quickly, we don't want the irq controller
 599          * thinking we're snobs just because some other CPU has
 600          * disabled global interrupts (we have already done the
 601          * INT_ACK cycles, it's too late to try to pretend to the
 602          * controller that we aren't taking the interrupt).
 603          *
 604          * 0 return value means that this irq is already being
 605          * handled by some other CPU. (or is disabled)
 606          */
 607         int cpu = smp_processor_id();
 608         irq_desc_t *desc = irq_desc + irq;
 609         struct irqaction * action;
 610         unsigned int status;
 611         static unsigned int illegal_count=0;
 612
 613         if ((unsigned) irq > ACTUAL_NR_IRQS && illegal_count < MAX_ILLEGAL_IRQS ) {
 614                 irq_err_count++;
 615                 illegal_count++;
 616                 printk(KERN_CRIT "device_interrupt: invalid interrupt %d\n",
 617                        irq);
 618                 return;
 619         }
 620
 621         irq_enter();
 622         kstat_cpu(cpu).irqs[irq]++;
 623         spin_lock_irq(&desc->lock); /* mask also the higher prio events */
 624         desc->handler->ack(irq);
 625         /*
 626          * REPLAY is when Linux resends an IRQ that was dropped earlier.
 627          * WAITING is used by probe to mark irqs that are being tested.
 628          */
 629         status = desc->status & ~(IRQ_REPLAY | IRQ_WAITING);
 630         status |= IRQ_PENDING; /* we _want_ to handle it */
 631
 632         /*
 633          * If the IRQ is disabled for whatever reason, we cannot
 634          * use the action we have.
 635          */
 636         action = NULL;
 637         if (!(status & (IRQ_DISABLED | IRQ_INPROGRESS))) {
 638                 action = desc->action;
 639                 status &= ~IRQ_PENDING; /* we commit to handling */
 640                 status |= IRQ_INPROGRESS; /* we are handling it */
 641         }
 642         desc->status = status;
 643
 644         /*
 645          * If there is no IRQ handler or it was disabled, exit early.
 646          * Since we set PENDING, if another processor is handling
 647          * a different instance of this same irq, the other processor
 648          * will take care of it.
 649          */
 650         if (!action)
 651                 goto out;
 652
 653         /*
 654          * Edge triggered interrupts need to remember pending events.
 655          * This applies to any hw interrupts that allow a second
 656          * instance of the same irq to arrive while we are in handle_irq
 657          * or in the handler. But the code here only handles the _second_
 658          * instance of the irq, not the third or fourth. So it is mostly
 659          * useful for irq hardware that does not mask cleanly in an
 660          * SMP environment.
 661          */
 662         for (;;) {
 663                 spin_unlock(&desc->lock);
 664                 handle_IRQ_event(irq, regs, action);
 665                 spin_lock(&desc->lock);
 666
 667                 if (!(desc->status & IRQ_PENDING)
 668                     || (desc->status & IRQ_LEVEL))
 669                         break;
 670                 desc->status &= ~IRQ_PENDING;
 671         }
 672         desc->status &= ~IRQ_INPROGRESS;
 673 out:
 674         /*
 675          * The ->end() handler has to deal with interrupts which got
 676          * disabled while the handler was running.
 677          */
 678         desc->handler->end(irq);
 679         spin_unlock(&desc->lock);
 680
 681         irq_exit();
 682 }
 683
 684 /*
 685  * IRQ autodetection code..
 686  *
 687  * This depends on the fact that any interrupt that
 688  * comes in on to an unassigned handler will get stuck
 689  * with "IRQ_WAITING" cleared and the interrupt
 690  * disabled.
 691  */
 692 unsigned long
 693 probe_irq_on(void)
 694 {
 695         int i;
 696         irq_desc_t *desc;
 697         unsigned long delay;
 698         unsigned long val;
 699
 700         /* Something may have generated an irq long ago and we want to
 701            flush such a longstanding irq before considering it as spurious. */
 702         for (i = NR_IRQS-1; i >= 0; i--) {
 703                 desc = irq_desc + i;
 704
 705                 spin_lock_irq(&desc->lock);
 706                 if (!irq_desc[i].action)
 707                         irq_desc[i].handler->startup(i);
 708                 spin_unlock_irq(&desc->lock);
 709         }
 710
 711         /* Wait for longstanding interrupts to trigger. */
 712         for (delay = jiffies + HZ/50; time_after(delay, jiffies); )
 713                 /* about 20ms delay */ barrier();
 714
 715         /* enable any unassigned irqs (we must startup again here because
 716            if a longstanding irq happened in the previous stage, it may have
 717            masked itself) first, enable any unassigned irqs. */
 718         for (i = NR_IRQS-1; i >= 0; i--) {
 719                 desc = irq_desc + i;
 720
 721                 spin_lock_irq(&desc->lock);
 722                 if (!desc->action) {
 723                         desc->status |= IRQ_AUTODETECT | IRQ_WAITING;
 724                         if (desc->handler->startup(i))
 725                                 desc->status |= IRQ_PENDING;
 726                 }
 727                 spin_unlock_irq(&desc->lock);
 728         }
 729
 730         /*
 731          * Wait for spurious interrupts to trigger
 732          */
 733         for (delay = jiffies + HZ/10; time_after(delay, jiffies); )
 734                 /* about 100ms delay */ barrier();
 735
 736         /*
 737          * Now filter out any obviously spurious interrupts
 738          */
 739         val = 0;
 740         for (i=0; i<NR_IRQS; i++) {
 741                 irq_desc_t *desc = irq_desc + i;
 742                 unsigned int status;
 743
 744                 spin_lock_irq(&desc->lock);
 745                 status = desc->status;
 746
 747                 if (status & IRQ_AUTODETECT) {
 748                         /* It triggered already - consider it spurious. */
 749                         if (!(status & IRQ_WAITING)) {
 750                                 desc->status = status & ~IRQ_AUTODETECT;
 751                                 desc->handler->shutdown(i);
 752                         } else
 753                                 if (i < 32)
 754                                         val |= 1 << i;
 755                 }
 756                 spin_unlock_irq(&desc->lock);
 757         }
 758
 759         return val;
 760 }
 761
 762 EXPORT_SYMBOL(probe_irq_on);
 763
 764 /*
 765  * Return a mask of triggered interrupts (this
 766  * can handle only legacy ISA interrupts).
 767  */
 768 unsigned int
 769 probe_irq_mask(unsigned long val)
 770 {
 771         int i;
 772         unsigned int mask;
 773
 774         mask = 0;
 775         for (i = 0; i < NR_IRQS; i++) {
 776                 irq_desc_t *desc = irq_desc + i;
 777                 unsigned int status;
 778
 779                 spin_lock_irq(&desc->lock);
 780                 status = desc->status;
 781
 782                 if (status & IRQ_AUTODETECT) {
 783                         /* We only react to ISA interrupts */
 784                         if (!(status & IRQ_WAITING)) {
 785                                 if (i < 16)
 786                                         mask |= 1 << i;
 787                         }
 788
 789                         desc->status = status & ~IRQ_AUTODETECT;
 790                         desc->handler->shutdown(i);
 791                 }
 792                 spin_unlock_irq(&desc->lock);
 793         }
 794
 795         return mask & val;
 796 }
 797
 798 /*
 799  * Get the result of the IRQ probe.. A negative result means that
 800  * we have several candidates (but we return the lowest-numbered
 801  * one).
 802  */
 803
 804 int
 805 probe_irq_off(unsigned long val)
 806 {
 807         int i, irq_found, nr_irqs;
 808
 809         nr_irqs = 0;
 810         irq_found = 0;
 811         for (i=0; i<NR_IRQS; i++) {
 812                 irq_desc_t *desc = irq_desc + i;
 813                 unsigned int status;
 814
 815                 spin_lock_irq(&desc->lock);
 816                 status = desc->status;
 817
 818                 if (status & IRQ_AUTODETECT) {
 819                         if (!(status & IRQ_WAITING)) {
 820                                 if (!nr_irqs)
 821                                         irq_found = i;
 822                                 nr_irqs++;
 823                         }
 824                         desc->status = status & ~IRQ_AUTODETECT;
 825                         desc->handler->shutdown(i);
 826                 }
 827                 spin_unlock_irq(&desc->lock);
 828         }
 829
 830         if (nr_irqs > 1)
 831                 irq_found = -irq_found;
 832         return irq_found;
 833 }
 834
 835 EXPORT_SYMBOL(probe_irq_off);
 836
 837 #ifdef CONFIG_SMP
 838 void synchronize_irq(unsigned int irq)
 839 {
 840         /* is there anything to synchronize with? */
 841         if (!irq_desc[irq].action)
 842                 return;
 843
 844         while (irq_desc[irq].status & IRQ_INPROGRESS)
 845                 barrier();
 846 }
 847 #endif