arch/arm/kernel/irq.c

   1 /*
   2  *  linux/arch/arm/kernel/irq.c
   3  *
   4  *  Copyright (C) 1992 Linus Torvalds
   5  *  Modifications for ARM processor Copyright (C) 1995-2000 Russell King.
   6  *
   7  * 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/kernel_stat.h>
  22 #include <linux/module.h>
  23 #include <linux/signal.h>
  24 #include <linux/ioport.h>
  25 #include <linux/interrupt.h>
  26 #include <linux/ptrace.h>
  27 #include <linux/slab.h>
  28 #include <linux/random.h>
  29 #include <linux/smp.h>
  30 #include <linux/init.h>
  31 #include <linux/seq_file.h>
  32 #include <linux/errno.h>
  33 #include <linux/list.h>
  34 #include <linux/kallsyms.h>
  35
  36 #include <asm/irq.h>
  37 #include <asm/system.h>
  38 #include <asm/mach/irq.h>
  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 void dummy_mask_unmask_irq(unsigned int irq)
  60 {
  61 }
  62
  63 irqreturn_t no_action(int irq, void *dev_id, struct pt_regs *regs)
  64 {
  65         return IRQ_NONE;
  66 }
  67
  68 void do_bad_IRQ(unsigned int irq, struct irqdesc *desc, struct pt_regs *regs)
  69 {
  70         irq_err_count += 1;
  71         printk(KERN_ERR "IRQ: spurious interrupt %d\n", irq);
  72 }
  73
  74 static struct irqchip bad_chip = {
  75         .ack    = dummy_mask_unmask_irq,
  76         .mask   = dummy_mask_unmask_irq,
  77         .unmask = dummy_mask_unmask_irq,
  78 };
  79
  80 static struct irqdesc bad_irq_desc = {
  81         .chip           = &bad_chip,
  82         .handle         = do_bad_IRQ,
  83         .pend           = LIST_HEAD_INIT(bad_irq_desc.pend),
  84         .disable_depth  = 1,
  85 };
  86
  87 /**
  88  *      disable_irq - disable an irq and wait for completion
  89  *      @irq: Interrupt to disable
  90  *
  91  *      Disable the selected interrupt line.  Enables and disables
  92  *      are nested.  We do this lazily.
  93  *
  94  *      This function may be called from IRQ context.
  95  */
  96 void disable_irq(unsigned int irq)
  97 {
  98         struct irqdesc *desc = irq_desc + irq;
  99         unsigned long flags;
 100
 101         spin_lock_irqsave(&irq_controller_lock, flags);
 102         desc->disable_depth++;
 103         list_del_init(&desc->pend);
 104         spin_unlock_irqrestore(&irq_controller_lock, flags);
 105 }
 106
 107 /**
 108  *      enable_irq - enable interrupt handling on an irq
 109  *      @irq: Interrupt to enable
 110  *
 111  *      Re-enables the processing of interrupts on this IRQ line.
 112  *      Note that this may call the interrupt handler, so you may
 113  *      get unexpected results if you hold IRQs disabled.
 114  *
 115  *      This function may be called from IRQ context.
 116  */
 117 void enable_irq(unsigned int irq)
 118 {
 119         struct irqdesc *desc = irq_desc + irq;
 120         unsigned long flags;
 121
 122         spin_lock_irqsave(&irq_controller_lock, flags);
 123         if (unlikely(!desc->disable_depth)) {
 124                 printk("enable_irq(%u) unbalanced from %p\n", irq,
 125                         __builtin_return_address(0));
 126         } else if (!--desc->disable_depth) {
 127                 desc->probing = 0;
 128                 desc->chip->unmask(irq);
 129
 130                 /*
 131                  * If the interrupt is waiting to be processed,
 132                  * try to re-run it.  We can't directly run it
 133                  * from here since the caller might be in an
 134                  * interrupt-protected region.
 135                  */
 136                 if (desc->pending && list_empty(&desc->pend)) {
 137                         desc->pending = 0;
 138                         if (!desc->chip->retrigger ||
 139                             desc->chip->retrigger(irq))
 140                                 list_add(&desc->pend, &irq_pending);
 141                 }
 142         }
 143         spin_unlock_irqrestore(&irq_controller_lock, flags);
 144 }
 145
 146 /*
 147  * Enable wake on selected irq
 148  */
 149 void enable_irq_wake(unsigned int irq)
 150 {
 151         struct irqdesc *desc = irq_desc + irq;
 152         unsigned long flags;
 153
 154         spin_lock_irqsave(&irq_controller_lock, flags);
 155         if (desc->chip->wake)
 156                 desc->chip->wake(irq, 1);
 157         spin_unlock_irqrestore(&irq_controller_lock, flags);
 158 }
 159
 160 void disable_irq_wake(unsigned int irq)
 161 {
 162         struct irqdesc *desc = irq_desc + irq;
 163         unsigned long flags;
 164
 165         spin_lock_irqsave(&irq_controller_lock, flags);
 166         if (desc->chip->wake)
 167                 desc->chip->wake(irq, 0);
 168         spin_unlock_irqrestore(&irq_controller_lock, flags);
 169 }
 170
 171 int show_interrupts(struct seq_file *p, void *v)
 172 {
 173         int i = *(loff_t *) v;
 174         struct irqaction * action;
 175         unsigned long flags;
 176
 177         if (i < NR_IRQS) {
 178                 spin_lock_irqsave(&irq_controller_lock, flags);
 179                 action = irq_desc[i].action;
 180                 if (!action)
 181                         goto unlock;
 182
 183                 seq_printf(p, "%3d: %10u ", i, kstat_irqs(i));
 184                 seq_printf(p, "  %s", action->name);
 185                 for (action = action->next; action; action = action->next)
 186                         seq_printf(p, ", %s", action->name);
 187
 188                 seq_putc(p, '\n');
 189 unlock:
 190                 spin_unlock_irqrestore(&irq_controller_lock, flags);
 191         } else if (i == NR_IRQS) {
 192 #ifdef CONFIG_ARCH_ACORN
 193                 show_fiq_list(p, v);
 194 #endif
 195                 seq_printf(p, "Err: %10lu\n", irq_err_count);
 196         }
 197         return 0;
 198 }
 199
 200 /*
 201  * IRQ lock detection.
 202  *
 203  * Hopefully, this should get us out of a few locked situations.
 204  * However, it may take a while for this to happen, since we need
 205  * a large number if IRQs to appear in the same jiffie with the
 206  * same instruction pointer (or within 2 instructions).
 207  */
 208 static int check_irq_lock(struct irqdesc *desc, int irq, struct pt_regs *regs)
 209 {
 210         unsigned long instr_ptr = instruction_pointer(regs);
 211
 212         if (desc->lck_jif == jiffies &&
 213             desc->lck_pc >= instr_ptr && desc->lck_pc < instr_ptr + 8) {
 214                 desc->lck_cnt += 1;
 215
 216                 if (desc->lck_cnt > MAX_IRQ_CNT) {
 217                         printk(KERN_ERR "IRQ LOCK: IRQ%d is locking the system, disabled\n", irq);
 218                         return 1;
 219                 }
 220         } else {
 221                 desc->lck_cnt = 0;
 222                 desc->lck_pc  = instruction_pointer(regs);
 223                 desc->lck_jif = jiffies;
 224         }
 225         return 0;
 226 }
 227
 228 static void
 229 report_bad_irq(unsigned int irq, struct pt_regs *regs, struct irqdesc *desc, int ret)
 230 {
 231         static int count = 100;
 232         struct irqaction *action;
 233
 234         if (!count)
 235                 return;
 236
 237         count--;
 238
 239         if (ret != IRQ_HANDLED && ret != IRQ_NONE) {
 240                 printk("irq%u: bogus retval mask %x\n", irq, ret);
 241         } else {
 242                 printk("irq%u: nobody cared\n", irq);
 243         }
 244         show_regs(regs);
 245         dump_stack();
 246         printk(KERN_ERR "handlers:");
 247         action = desc->action;
 248         do {
 249                 printk("\n" KERN_ERR "[<%p>]", action->handler);
 250                 print_symbol(" (%s)", (unsigned long)action->handler);
 251                 action = action->next;
 252         } while (action);
 253         printk("\n");
 254 }
 255
 256 static int
 257 __do_irq(unsigned int irq, struct irqaction *action, struct pt_regs *regs)
 258 {
 259         unsigned int status;
 260         int retval = 0;
 261
 262         spin_unlock(&irq_controller_lock);
 263
 264         if (!(action->flags & SA_INTERRUPT))
 265                 local_irq_enable();
 266
 267         status = 0;
 268         do {
 269                 status |= action->flags;
 270                 retval |= action->handler(irq, action->dev_id, regs);
 271                 action = action->next;
 272         } while (action);
 273
 274         if (status & SA_SAMPLE_RANDOM)
 275                 add_interrupt_randomness(irq);
 276
 277         spin_lock_irq(&irq_controller_lock);
 278
 279         return retval;
 280 }
 281
 282 /*
 283  * This is for software-decoded IRQs.  The caller is expected to
 284  * handle the ack, clear, mask and unmask issues.
 285  */
 286 void
 287 do_simple_IRQ(unsigned int irq, struct irqdesc *desc, struct pt_regs *regs)
 288 {
 289         struct irqaction *action;
 290         const int cpu = smp_processor_id();
 291
 292         desc->triggered = 1;
 293
 294         kstat_cpu(cpu).irqs[irq]++;
 295
 296         action = desc->action;
 297         if (action) {
 298                 int ret = __do_irq(irq, action, regs);
 299                 if (ret != IRQ_HANDLED)
 300                         report_bad_irq(irq, regs, desc, ret);
 301         }
 302 }
 303
 304 /*
 305  * Most edge-triggered IRQ implementations seem to take a broken
 306  * approach to this.  Hence the complexity.
 307  */
 308 void
 309 do_edge_IRQ(unsigned int irq, struct irqdesc *desc, struct pt_regs *regs)
 310 {
 311         const int cpu = smp_processor_id();
 312
 313         desc->triggered = 1;
 314
 315         /*
 316          * If we're currently running this IRQ, or its disabled,
 317          * we shouldn't process the IRQ.  Instead, turn on the
 318          * hardware masks.
 319          */
 320         if (unlikely(desc->running || desc->disable_depth))
 321                 goto running;
 322
 323         /*
 324          * Acknowledge and clear the IRQ, but don't mask it.
 325          */
 326         desc->chip->ack(irq);
 327
 328         /*
 329          * Mark the IRQ currently in progress.
 330          */
 331         desc->running = 1;
 332
 333         kstat_cpu(cpu).irqs[irq]++;
 334
 335         do {
 336                 struct irqaction *action;
 337                 int ret;
 338
 339                 action = desc->action;
 340                 if (!action)
 341                         break;
 342
 343                 if (desc->pending && !desc->disable_depth) {
 344                         desc->pending = 0;
 345                         desc->chip->unmask(irq);
 346                 }
 347
 348                 ret = __do_irq(irq, action, regs);
 349                 if (ret != IRQ_HANDLED)
 350                         report_bad_irq(irq, regs, desc, ret);
 351         } while (desc->pending && !desc->disable_depth);
 352
 353         desc->running = 0;
 354
 355         /*
 356          * If we were disabled or freed, shut down the handler.
 357          */
 358         if (likely(desc->action && !check_irq_lock(desc, irq, regs)))
 359                 return;
 360
 361  running:
 362         /*
 363          * We got another IRQ while this one was masked or
 364          * currently running.  Delay it.
 365          */
 366         desc->pending = 1;
 367         desc->chip->mask(irq);
 368         desc->chip->ack(irq);
 369 }
 370
 371 /*
 372  * Level-based IRQ handler.  Nice and simple.
 373  */
 374 void
 375 do_level_IRQ(unsigned int irq, struct irqdesc *desc, struct pt_regs *regs)
 376 {
 377         struct irqaction *action;
 378         const int cpu = smp_processor_id();
 379
 380         desc->triggered = 1;
 381
 382         /*
 383          * Acknowledge, clear _AND_ disable the interrupt.
 384          */
 385         desc->chip->ack(irq);
 386
 387         if (likely(!desc->disable_depth)) {
 388                 kstat_cpu(cpu).irqs[irq]++;
 389
 390                 /*
 391                  * Return with this interrupt masked if no action
 392                  */
 393                 action = desc->action;
 394                 if (action) {
 395                         int ret = __do_irq(irq, desc->action, regs);
 396
 397                         if (ret != IRQ_HANDLED)
 398                                 report_bad_irq(irq, regs, desc, ret);
 399
 400                         if (likely(!desc->disable_depth &&
 401                                    !check_irq_lock(desc, irq, regs)))
 402                                 desc->chip->unmask(irq);
 403                 }
 404         }
 405 }
 406
 407 static void do_pending_irqs(struct pt_regs *regs)
 408 {
 409         struct list_head head, *l, *n;
 410
 411         do {
 412                 struct irqdesc *desc;
 413
 414                 /*
 415                  * First, take the pending interrupts off the list.
 416                  * The act of calling the handlers may add some IRQs
 417                  * back onto the list.
 418                  */
 419                 head = irq_pending;
 420                 INIT_LIST_HEAD(&irq_pending);
 421                 head.next->prev = &head;
 422                 head.prev->next = &head;
 423
 424                 /*
 425                  * Now run each entry.  We must delete it from our
 426                  * list before calling the handler.
 427                  */
 428                 list_for_each_safe(l, n, &head) {
 429                         desc = list_entry(l, struct irqdesc, pend);
 430                         list_del_init(&desc->pend);
 431                         desc->handle(desc - irq_desc, desc, regs);
 432                 }
 433
 434                 /*
 435                  * The list must be empty.
 436                  */
 437                 BUG_ON(!list_empty(&head));
 438         } while (!list_empty(&irq_pending));
 439 }
 440
 441 /*
 442  * do_IRQ handles all hardware IRQ's.  Decoded IRQs should not
 443  * come via this function.  Instead, they should provide their
 444  * own 'handler'
 445  */
 446 asmlinkage void asm_do_IRQ(int irq, struct pt_regs *regs)
 447 {
 448         struct irqdesc *desc = irq_desc + irq;
 449
 450         /*
 451          * Some hardware gives randomly wrong interrupts.  Rather
 452          * than crashing, do something sensible.
 453          */
 454         if (irq >= NR_IRQS)
 455                 desc = &bad_irq_desc;
 456
 457         irq_enter();
 458         spin_lock(&irq_controller_lock);
 459         desc->handle(irq, desc, regs);
 460
 461         /*
 462          * Now re-run any pending interrupts.
 463          */
 464         if (!list_empty(&irq_pending))
 465                 do_pending_irqs(regs);
 466
 467         spin_unlock(&irq_controller_lock);
 468         irq_exit();
 469 }
 470
 471 void __set_irq_handler(unsigned int irq, irq_handler_t handle, int is_chained)
 472 {
 473         struct irqdesc *desc;
 474         unsigned long flags;
 475
 476         if (irq >= NR_IRQS) {
 477                 printk(KERN_ERR "Trying to install handler for IRQ%d\n", irq);
 478                 return;
 479         }
 480
 481         if (handle == NULL)
 482                 handle = do_bad_IRQ;
 483
 484         desc = irq_desc + irq;
 485
 486         if (is_chained && desc->chip == &bad_chip)
 487                 printk(KERN_WARNING "Trying to install chained handler for IRQ%d\n", irq);
 488
 489         spin_lock_irqsave(&irq_controller_lock, flags);
 490         if (handle == do_bad_IRQ) {
 491                 desc->chip->mask(irq);
 492                 desc->chip->ack(irq);
 493                 desc->disable_depth = 1;
 494         }
 495         desc->handle = handle;
 496         if (handle != do_bad_IRQ && is_chained) {
 497                 desc->valid = 0;
 498                 desc->probe_ok = 0;
 499                 desc->disable_depth = 0;
 500                 desc->chip->unmask(irq);
 501         }
 502         spin_unlock_irqrestore(&irq_controller_lock, flags);
 503 }
 504
 505 void set_irq_chip(unsigned int irq, struct irqchip *chip)
 506 {
 507         struct irqdesc *desc;
 508         unsigned long flags;
 509
 510         if (irq >= NR_IRQS) {
 511                 printk(KERN_ERR "Trying to install chip for IRQ%d\n", irq);
 512                 return;
 513         }
 514
 515         if (chip == NULL)
 516                 chip = &bad_chip;
 517
 518         desc = irq_desc + irq;
 519         spin_lock_irqsave(&irq_controller_lock, flags);
 520         desc->chip = chip;
 521         spin_unlock_irqrestore(&irq_controller_lock, flags);
 522 }
 523
 524 int set_irq_type(unsigned int irq, unsigned int type)
 525 {
 526         struct irqdesc *desc;
 527         unsigned long flags;
 528         int ret = -ENXIO;
 529
 530         if (irq >= NR_IRQS) {
 531                 printk(KERN_ERR "Trying to set irq type for IRQ%d\n", irq);
 532                 return -ENODEV;
 533         }
 534
 535         desc = irq_desc + irq;
 536         if (desc->chip->type) {
 537                 spin_lock_irqsave(&irq_controller_lock, flags);
 538                 ret = desc->chip->type(irq, type);
 539                 spin_unlock_irqrestore(&irq_controller_lock, flags);
 540         }
 541
 542         return ret;
 543 }
 544
 545 void set_irq_flags(unsigned int irq, unsigned int iflags)
 546 {
 547         struct irqdesc *desc;
 548         unsigned long flags;
 549
 550         if (irq >= NR_IRQS) {
 551                 printk(KERN_ERR "Trying to set irq flags for IRQ%d\n", irq);
 552                 return;
 553         }
 554
 555         desc = irq_desc + irq;
 556         spin_lock_irqsave(&irq_controller_lock, flags);
 557         desc->valid = (iflags & IRQF_VALID) != 0;
 558         desc->probe_ok = (iflags & IRQF_PROBE) != 0;
 559         desc->noautoenable = (iflags & IRQF_NOAUTOEN) != 0;
 560         spin_unlock_irqrestore(&irq_controller_lock, flags);
 561 }
 562
 563 int setup_irq(unsigned int irq, struct irqaction *new)
 564 {
 565         int shared = 0;
 566         struct irqaction *old, **p;
 567         unsigned long flags;
 568         struct irqdesc *desc;
 569
 570         /*
 571          * Some drivers like serial.c use request_irq() heavily,
 572          * so we have to be careful not to interfere with a
 573          * running system.
 574          */
 575         if (new->flags & SA_SAMPLE_RANDOM) {
 576                 /*
 577                  * This function might sleep, we want to call it first,
 578                  * outside of the atomic block.
 579                  * Yes, this might clear the entropy pool if the wrong
 580                  * driver is attempted to be loaded, without actually
 581                  * installing a new handler, but is this really a problem,
 582                  * only the sysadmin is able to do this.
 583                  */
 584                 rand_initialize_irq(irq);
 585         }
 586
 587         /*
 588          * The following block of code has to be executed atomically
 589          */
 590         desc = irq_desc + irq;
 591         spin_lock_irqsave(&irq_controller_lock, flags);
 592         p = &desc->action;
 593         if ((old = *p) != NULL) {
 594                 /* Can't share interrupts unless both agree to */
 595                 if (!(old->flags & new->flags & SA_SHIRQ)) {
 596                         spin_unlock_irqrestore(&irq_controller_lock, flags);
 597                         return -EBUSY;
 598                 }
 599
 600                 /* add new interrupt at end of irq queue */
 601                 do {
 602                         p = &old->next;
 603                         old = *p;
 604                 } while (old);
 605                 shared = 1;
 606         }
 607
 608         *p = new;
 609
 610         if (!shared) {
 611                 desc->probing = 0;
 612                 desc->running = 0;
 613                 desc->pending = 0;
 614                 desc->disable_depth = 1;
 615                 if (!desc->noautoenable) {
 616                         desc->disable_depth = 0;
 617                         desc->chip->unmask(irq);
 618                 }
 619         }
 620
 621         spin_unlock_irqrestore(&irq_controller_lock, flags);
 622         return 0;
 623 }
 624
 625 /**
 626  *      request_irq - allocate an interrupt line
 627  *      @irq: Interrupt line to allocate
 628  *      @handler: Function to be called when the IRQ occurs
 629  *      @irqflags: Interrupt type flags
 630  *      @devname: An ascii name for the claiming device
 631  *      @dev_id: A cookie passed back to the handler function
 632  *
 633  *      This call allocates interrupt resources and enables the
 634  *      interrupt line and IRQ handling. From the point this
 635  *      call is made your handler function may be invoked. Since
 636  *      your handler function must clear any interrupt the board
 637  *      raises, you must take care both to initialise your hardware
 638  *      and to set up the interrupt handler in the right order.
 639  *
 640  *      Dev_id must be globally unique. Normally the address of the
 641  *      device data structure is used as the cookie. Since the handler
 642  *      receives this value it makes sense to use it.
 643  *
 644  *      If your interrupt is shared you must pass a non NULL dev_id
 645  *      as this is required when freeing the interrupt.
 646  *
 647  *      Flags:
 648  *
 649  *      SA_SHIRQ                Interrupt is shared
 650  *
 651  *      SA_INTERRUPT            Disable local interrupts while processing
 652  *
 653  *      SA_SAMPLE_RANDOM        The interrupt can be used for entropy
 654  *
 655  */
 656 int request_irq(unsigned int irq, irqreturn_t (*handler)(int, void *, struct pt_regs *),
 657                  unsigned long irq_flags, const char * devname, void *dev_id)
 658 {
 659         unsigned long retval;
 660         struct irqaction *action;
 661
 662         if (irq >= NR_IRQS || !irq_desc[irq].valid || !handler ||
 663             (irq_flags & SA_SHIRQ && !dev_id))
 664                 return -EINVAL;
 665
 666         action = (struct irqaction *)kmalloc(sizeof(struct irqaction), GFP_KERNEL);
 667         if (!action)
 668                 return -ENOMEM;
 669
 670         action->handler = handler;
 671         action->flags = irq_flags;
 672         action->mask = 0;
 673         action->name = devname;
 674         action->next = NULL;
 675         action->dev_id = dev_id;
 676
 677         retval = setup_irq(irq, action);
 678
 679         if (retval)
 680                 kfree(action);
 681         return retval;
 682 }
 683
 684 EXPORT_SYMBOL(request_irq);
 685
 686 /**
 687  *      free_irq - free an interrupt
 688  *      @irq: Interrupt line to free
 689  *      @dev_id: Device identity to free
 690  *
 691  *      Remove an interrupt handler. The handler is removed and if the
 692  *      interrupt line is no longer in use by any driver it is disabled.
 693  *      On a shared IRQ the caller must ensure the interrupt is disabled
 694  *      on the card it drives before calling this function.
 695  *
 696  *      This function must not be called from interrupt context.
 697  */
 698 void free_irq(unsigned int irq, void *dev_id)
 699 {
 700         struct irqaction * action, **p;
 701         unsigned long flags;
 702
 703         if (irq >= NR_IRQS || !irq_desc[irq].valid) {
 704                 printk(KERN_ERR "Trying to free IRQ%d\n",irq);
 705                 dump_stack();
 706                 return;
 707         }
 708
 709         spin_lock_irqsave(&irq_controller_lock, flags);
 710         for (p = &irq_desc[irq].action; (action = *p) != NULL; p = &action->next) {
 711                 if (action->dev_id != dev_id)
 712                         continue;
 713
 714                 /* Found it - now free it */
 715                 *p = action->next;
 716                 break;
 717         }
 718         spin_unlock_irqrestore(&irq_controller_lock, flags);
 719
 720         if (!action) {
 721                 printk(KERN_ERR "Trying to free free IRQ%d\n",irq);
 722                 dump_stack();
 723         } else {
 724                 synchronize_irq(irq);
 725                 kfree(action);
 726         }
 727 }
 728
 729 EXPORT_SYMBOL(free_irq);
 730
 731 static DECLARE_MUTEX(probe_sem);
 732
 733 /* Start the interrupt probing.  Unlike other architectures,
 734  * we don't return a mask of interrupts from probe_irq_on,
 735  * but return the number of interrupts enabled for the probe.
 736  * The interrupts which have been enabled for probing is
 737  * instead recorded in the irq_desc structure.
 738  */
 739 unsigned long probe_irq_on(void)
 740 {
 741         unsigned int i, irqs = 0;
 742         unsigned long delay;
 743
 744         down(&probe_sem);
 745
 746         /*
 747          * first snaffle up any unassigned but
 748          * probe-able interrupts
 749          */
 750         spin_lock_irq(&irq_controller_lock);
 751         for (i = 0; i < NR_IRQS; i++) {
 752                 if (!irq_desc[i].probe_ok || irq_desc[i].action)
 753                         continue;
 754
 755                 irq_desc[i].probing = 1;
 756                 irq_desc[i].triggered = 0;
 757                 if (irq_desc[i].chip->type)
 758                         irq_desc[i].chip->type(i, IRQT_PROBE);
 759                 irq_desc[i].chip->unmask(i);
 760                 irqs += 1;
 761         }
 762         spin_unlock_irq(&irq_controller_lock);
 763
 764         /*
 765          * wait for spurious interrupts to mask themselves out again
 766          */
 767         for (delay = jiffies + HZ/10; time_before(jiffies, delay); )
 768                 /* min 100ms delay */;
 769
 770         /*
 771          * now filter out any obviously spurious interrupts
 772          */
 773         spin_lock_irq(&irq_controller_lock);
 774         for (i = 0; i < NR_IRQS; i++) {
 775                 if (irq_desc[i].probing && irq_desc[i].triggered) {
 776                         irq_desc[i].probing = 0;
 777                         irqs -= 1;
 778                 }
 779         }
 780         spin_unlock_irq(&irq_controller_lock);
 781
 782         return irqs;
 783 }
 784
 785 EXPORT_SYMBOL(probe_irq_on);
 786
 787 unsigned int probe_irq_mask(unsigned long irqs)
 788 {
 789         unsigned int mask = 0, i;
 790
 791         spin_lock_irq(&irq_controller_lock);
 792         for (i = 0; i < 16 && i < NR_IRQS; i++)
 793                 if (irq_desc[i].probing && irq_desc[i].triggered)
 794                         mask |= 1 << i;
 795         spin_unlock_irq(&irq_controller_lock);
 796
 797         up(&probe_sem);
 798
 799         return mask;
 800 }
 801
 802 /*
 803  * Possible return values:
 804  *  >= 0 - interrupt number
 805  *    -1 - no interrupt/many interrupts
 806  */
 807 int probe_irq_off(unsigned long irqs)
 808 {
 809         unsigned int i;
 810         int irq_found = NO_IRQ;
 811
 812         /*
 813          * look at the interrupts, and find exactly one
 814          * that we were probing has been triggered
 815          */
 816         spin_lock_irq(&irq_controller_lock);
 817         for (i = 0; i < NR_IRQS; i++) {
 818                 if (irq_desc[i].probing &&
 819                     irq_desc[i].triggered) {
 820                         if (irq_found != NO_IRQ) {
 821                                 irq_found = NO_IRQ;
 822                                 goto out;
 823                         }
 824                         irq_found = i;
 825                 }
 826         }
 827
 828         if (irq_found == -1)
 829                 irq_found = NO_IRQ;
 830 out:
 831         spin_unlock_irq(&irq_controller_lock);
 832
 833         up(&probe_sem);
 834
 835         return irq_found;
 836 }
 837
 838 EXPORT_SYMBOL(probe_irq_off);
 839
 840 void __init init_irq_proc(void)
 841 {
 842 }
 843
 844 void __init init_IRQ(void)
 845 {
 846         struct irqdesc *desc;
 847         extern void init_dma(void);
 848         int irq;
 849
 850         for (irq = 0, desc = irq_desc; irq < NR_IRQS; irq++, desc++) {
 851                 *desc = bad_irq_desc;
 852                 INIT_LIST_HEAD(&desc->pend);
 853         }
 854
 855         init_arch_irq();
 856         init_dma();
 857 }