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 = SPIN_LOCK_UNLOCKED;
  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 EXPORT_SYMBOL(disable_irq);
 107
 108 /**
 109  *      enable_irq - enable interrupt handling on an irq
 110  *      @irq: Interrupt to enable
 111  *
 112  *      Re-enables the processing of interrupts on this IRQ line.
 113  *      Note that this may call the interrupt handler, so you may
 114  *      get unexpected results if you hold IRQs disabled.
 115  *
 116  *      This function may be called from IRQ context.
 117  */
 118 void enable_irq(unsigned int irq)
 119 {
 120         struct irqdesc *desc = irq_desc + irq;
 121         unsigned long flags;
 122
 123         spin_lock_irqsave(&irq_controller_lock, flags);
 124         if (unlikely(!desc->disable_depth)) {
 125                 printk("enable_irq(%u) unbalanced from %p\n", irq,
 126                         __builtin_return_address(0));
 127         } else if (!--desc->disable_depth) {
 128                 desc->probing = 0;
 129                 desc->chip->unmask(irq);
 130
 131                 /*
 132                  * If the interrupt is waiting to be processed,
 133                  * try to re-run it.  We can't directly run it
 134                  * from here since the caller might be in an
 135                  * interrupt-protected region.
 136                  */
 137                 if (desc->pending && list_empty(&desc->pend)) {
 138                         desc->pending = 0;
 139                         if (!desc->chip->retrigger ||
 140                             desc->chip->retrigger(irq))
 141                                 list_add(&desc->pend, &irq_pending);
 142                 }
 143         }
 144         spin_unlock_irqrestore(&irq_controller_lock, flags);
 145 }
 146 EXPORT_SYMBOL(enable_irq);
 147
 148 /*
 149  * Enable wake on selected irq
 150  */
 151 void enable_irq_wake(unsigned int irq)
 152 {
 153         struct irqdesc *desc = irq_desc + irq;
 154         unsigned long flags;
 155
 156         spin_lock_irqsave(&irq_controller_lock, flags);
 157         if (desc->chip->wake)
 158                 desc->chip->wake(irq, 1);
 159         spin_unlock_irqrestore(&irq_controller_lock, flags);
 160 }
 161 EXPORT_SYMBOL(enable_irq_wake);
 162
 163 void disable_irq_wake(unsigned int irq)
 164 {
 165         struct irqdesc *desc = irq_desc + irq;
 166         unsigned long flags;
 167
 168         spin_lock_irqsave(&irq_controller_lock, flags);
 169         if (desc->chip->wake)
 170                 desc->chip->wake(irq, 0);
 171         spin_unlock_irqrestore(&irq_controller_lock, flags);
 172 }
 173 EXPORT_SYMBOL(disable_irq_wake);
 174
 175 int show_interrupts(struct seq_file *p, void *v)
 176 {
 177         int i = *(loff_t *) v;
 178         struct irqaction * action;
 179         unsigned long flags;
 180
 181         if (i < NR_IRQS) {
 182                 spin_lock_irqsave(&irq_controller_lock, flags);
 183                 action = irq_desc[i].action;
 184                 if (!action)
 185                         goto unlock;
 186
 187                 seq_printf(p, "%3d: %10u ", i, kstat_irqs(i));
 188                 seq_printf(p, "  %s", action->name);
 189                 for (action = action->next; action; action = action->next)
 190                         seq_printf(p, ", %s", action->name);
 191
 192                 seq_putc(p, '\n');
 193 unlock:
 194                 spin_unlock_irqrestore(&irq_controller_lock, flags);
 195         } else if (i == NR_IRQS) {
 196 #ifdef CONFIG_ARCH_ACORN
 197                 show_fiq_list(p, v);
 198 #endif
 199                 seq_printf(p, "Err: %10lu\n", irq_err_count);
 200         }
 201         return 0;
 202 }
 203
 204 /*
 205  * IRQ lock detection.
 206  *
 207  * Hopefully, this should get us out of a few locked situations.
 208  * However, it may take a while for this to happen, since we need
 209  * a large number if IRQs to appear in the same jiffie with the
 210  * same instruction pointer (or within 2 instructions).
 211  */
 212 static int check_irq_lock(struct irqdesc *desc, int irq, struct pt_regs *regs)
 213 {
 214         unsigned long instr_ptr = instruction_pointer(regs);
 215
 216         if (desc->lck_jif == jiffies &&
 217             desc->lck_pc >= instr_ptr && desc->lck_pc < instr_ptr + 8) {
 218                 desc->lck_cnt += 1;
 219
 220                 if (desc->lck_cnt > MAX_IRQ_CNT) {
 221                         printk(KERN_ERR "IRQ LOCK: IRQ%d is locking the system, disabled\n", irq);
 222                         return 1;
 223                 }
 224         } else {
 225                 desc->lck_cnt = 0;
 226                 desc->lck_pc  = instruction_pointer(regs);
 227                 desc->lck_jif = jiffies;
 228         }
 229         return 0;
 230 }
 231
 232 static void
 233 report_bad_irq(unsigned int irq, struct pt_regs *regs, struct irqdesc *desc, int ret)
 234 {
 235         static int count = 100;
 236         struct irqaction *action;
 237
 238         if (!count)
 239                 return;
 240
 241         count--;
 242
 243         if (ret != IRQ_HANDLED && ret != IRQ_NONE) {
 244                 printk("irq%u: bogus retval mask %x\n", irq, ret);
 245         } else {
 246                 printk("irq%u: nobody cared\n", irq);
 247         }
 248         show_regs(regs);
 249         dump_stack();
 250         printk(KERN_ERR "handlers:");
 251         action = desc->action;
 252         do {
 253                 printk("\n" KERN_ERR "[<%p>]", action->handler);
 254                 print_symbol(" (%s)", (unsigned long)action->handler);
 255                 action = action->next;
 256         } while (action);
 257         printk("\n");
 258 }
 259
 260 static int
 261 __do_irq(unsigned int irq, struct irqaction *action, struct pt_regs *regs)
 262 {
 263         unsigned int status;
 264         int retval = 0;
 265
 266         spin_unlock(&irq_controller_lock);
 267
 268         if (!(action->flags & SA_INTERRUPT))
 269                 local_irq_enable();
 270
 271         status = 0;
 272         do {
 273                 status |= action->flags;
 274                 retval |= action->handler(irq, action->dev_id, regs);
 275                 action = action->next;
 276         } while (action);
 277
 278         if (status & SA_SAMPLE_RANDOM)
 279                 add_interrupt_randomness(irq);
 280
 281         spin_lock_irq(&irq_controller_lock);
 282
 283         return retval;
 284 }
 285
 286 /*
 287  * This is for software-decoded IRQs.  The caller is expected to
 288  * handle the ack, clear, mask and unmask issues.
 289  */
 290 void
 291 do_simple_IRQ(unsigned int irq, struct irqdesc *desc, struct pt_regs *regs)
 292 {
 293         struct irqaction *action;
 294         const int cpu = smp_processor_id();
 295
 296         desc->triggered = 1;
 297
 298         kstat_cpu(cpu).irqs[irq]++;
 299
 300         action = desc->action;
 301         if (action) {
 302                 int ret = __do_irq(irq, action, regs);
 303                 if (ret != IRQ_HANDLED)
 304                         report_bad_irq(irq, regs, desc, ret);
 305         }
 306 }
 307
 308 /*
 309  * Most edge-triggered IRQ implementations seem to take a broken
 310  * approach to this.  Hence the complexity.
 311  */
 312 void
 313 do_edge_IRQ(unsigned int irq, struct irqdesc *desc, struct pt_regs *regs)
 314 {
 315         const int cpu = smp_processor_id();
 316
 317         desc->triggered = 1;
 318
 319         /*
 320          * If we're currently running this IRQ, or its disabled,
 321          * we shouldn't process the IRQ.  Instead, turn on the
 322          * hardware masks.
 323          */
 324         if (unlikely(desc->running || desc->disable_depth))
 325                 goto running;
 326
 327         /*
 328          * Acknowledge and clear the IRQ, but don't mask it.
 329          */
 330         desc->chip->ack(irq);
 331
 332         /*
 333          * Mark the IRQ currently in progress.
 334          */
 335         desc->running = 1;
 336
 337         kstat_cpu(cpu).irqs[irq]++;
 338
 339         do {
 340                 struct irqaction *action;
 341                 int ret;
 342
 343                 action = desc->action;
 344                 if (!action)
 345                         break;
 346
 347                 if (desc->pending && !desc->disable_depth) {
 348                         desc->pending = 0;
 349                         desc->chip->unmask(irq);
 350                 }
 351
 352                 ret = __do_irq(irq, action, regs);
 353                 if (ret != IRQ_HANDLED)
 354                         report_bad_irq(irq, regs, desc, ret);
 355         } while (desc->pending && !desc->disable_depth);
 356
 357         desc->running = 0;
 358
 359         /*
 360          * If we were disabled or freed, shut down the handler.
 361          */
 362         if (likely(desc->action && !check_irq_lock(desc, irq, regs)))
 363                 return;
 364
 365  running:
 366         /*
 367          * We got another IRQ while this one was masked or
 368          * currently running.  Delay it.
 369          */
 370         desc->pending = 1;
 371         desc->chip->mask(irq);
 372         desc->chip->ack(irq);
 373 }
 374
 375 /*
 376  * Level-based IRQ handler.  Nice and simple.
 377  */
 378 void
 379 do_level_IRQ(unsigned int irq, struct irqdesc *desc, struct pt_regs *regs)
 380 {
 381         struct irqaction *action;
 382         const int cpu = smp_processor_id();
 383
 384         desc->triggered = 1;
 385
 386         /*
 387          * Acknowledge, clear _AND_ disable the interrupt.
 388          */
 389         desc->chip->ack(irq);
 390
 391         if (likely(!desc->disable_depth)) {
 392                 kstat_cpu(cpu).irqs[irq]++;
 393
 394                 /*
 395                  * Return with this interrupt masked if no action
 396                  */
 397                 action = desc->action;
 398                 if (action) {
 399                         int ret = __do_irq(irq, desc->action, regs);
 400
 401                         if (ret != IRQ_HANDLED)
 402                                 report_bad_irq(irq, regs, desc, ret);
 403
 404                         if (likely(!desc->disable_depth &&
 405                                    !check_irq_lock(desc, irq, regs)))
 406                                 desc->chip->unmask(irq);
 407                 }
 408         }
 409 }
 410
 411 static void do_pending_irqs(struct pt_regs *regs)
 412 {
 413         struct list_head head, *l, *n;
 414
 415         do {
 416                 struct irqdesc *desc;
 417
 418                 /*
 419                  * First, take the pending interrupts off the list.
 420                  * The act of calling the handlers may add some IRQs
 421                  * back onto the list.
 422                  */
 423                 head = irq_pending;
 424                 INIT_LIST_HEAD(&irq_pending);
 425                 head.next->prev = &head;
 426                 head.prev->next = &head;
 427
 428                 /*
 429                  * Now run each entry.  We must delete it from our
 430                  * list before calling the handler.
 431                  */
 432                 list_for_each_safe(l, n, &head) {
 433                         desc = list_entry(l, struct irqdesc, pend);
 434                         list_del_init(&desc->pend);
 435                         desc->handle(desc - irq_desc, desc, regs);
 436                 }
 437
 438                 /*
 439                  * The list must be empty.
 440                  */
 441                 BUG_ON(!list_empty(&head));
 442         } while (!list_empty(&irq_pending));
 443 }
 444
 445 /*
 446  * do_IRQ handles all hardware IRQ's.  Decoded IRQs should not
 447  * come via this function.  Instead, they should provide their
 448  * own 'handler'
 449  */
 450 asmlinkage void asm_do_IRQ(unsigned int irq, struct pt_regs *regs)
 451 {
 452         struct irqdesc *desc = irq_desc + irq;
 453
 454         /*
 455          * Some hardware gives randomly wrong interrupts.  Rather
 456          * than crashing, do something sensible.
 457          */
 458         if (irq >= NR_IRQS)
 459                 desc = &bad_irq_desc;
 460
 461         irq_enter();
 462         spin_lock(&irq_controller_lock);
 463         desc->handle(irq, desc, regs);
 464
 465         /*
 466          * Now re-run any pending interrupts.
 467          */
 468         if (!list_empty(&irq_pending))
 469                 do_pending_irqs(regs);
 470
 471         spin_unlock(&irq_controller_lock);
 472         irq_exit();
 473 }
 474
 475 void __set_irq_handler(unsigned int irq, irq_handler_t handle, int is_chained)
 476 {
 477         struct irqdesc *desc;
 478         unsigned long flags;
 479
 480         if (irq >= NR_IRQS) {
 481                 printk(KERN_ERR "Trying to install handler for IRQ%d\n", irq);
 482                 return;
 483         }
 484
 485         if (handle == NULL)
 486                 handle = do_bad_IRQ;
 487
 488         desc = irq_desc + irq;
 489
 490         if (is_chained && desc->chip == &bad_chip)
 491                 printk(KERN_WARNING "Trying to install chained handler for IRQ%d\n", irq);
 492
 493         spin_lock_irqsave(&irq_controller_lock, flags);
 494         if (handle == do_bad_IRQ) {
 495                 desc->chip->mask(irq);
 496                 desc->chip->ack(irq);
 497                 desc->disable_depth = 1;
 498         }
 499         desc->handle = handle;
 500         if (handle != do_bad_IRQ && is_chained) {
 501                 desc->valid = 0;
 502                 desc->probe_ok = 0;
 503                 desc->disable_depth = 0;
 504                 desc->chip->unmask(irq);
 505         }
 506         spin_unlock_irqrestore(&irq_controller_lock, flags);
 507 }
 508
 509 void set_irq_chip(unsigned int irq, struct irqchip *chip)
 510 {
 511         struct irqdesc *desc;
 512         unsigned long flags;
 513
 514         if (irq >= NR_IRQS) {
 515                 printk(KERN_ERR "Trying to install chip for IRQ%d\n", irq);
 516                 return;
 517         }
 518
 519         if (chip == NULL)
 520                 chip = &bad_chip;
 521
 522         desc = irq_desc + irq;
 523         spin_lock_irqsave(&irq_controller_lock, flags);
 524         desc->chip = chip;
 525         spin_unlock_irqrestore(&irq_controller_lock, flags);
 526 }
 527
 528 int set_irq_type(unsigned int irq, unsigned int type)
 529 {
 530         struct irqdesc *desc;
 531         unsigned long flags;
 532         int ret = -ENXIO;
 533
 534         if (irq >= NR_IRQS) {
 535                 printk(KERN_ERR "Trying to set irq type for IRQ%d\n", irq);
 536                 return -ENODEV;
 537         }
 538
 539         desc = irq_desc + irq;
 540         if (desc->chip->type) {
 541                 spin_lock_irqsave(&irq_controller_lock, flags);
 542                 ret = desc->chip->type(irq, type);
 543                 spin_unlock_irqrestore(&irq_controller_lock, flags);
 544         }
 545
 546         return ret;
 547 }
 548 EXPORT_SYMBOL(set_irq_type);
 549
 550 void set_irq_flags(unsigned int irq, unsigned int iflags)
 551 {
 552         struct irqdesc *desc;
 553         unsigned long flags;
 554
 555         if (irq >= NR_IRQS) {
 556                 printk(KERN_ERR "Trying to set irq flags for IRQ%d\n", irq);
 557                 return;
 558         }
 559
 560         desc = irq_desc + irq;
 561         spin_lock_irqsave(&irq_controller_lock, flags);
 562         desc->valid = (iflags & IRQF_VALID) != 0;
 563         desc->probe_ok = (iflags & IRQF_PROBE) != 0;
 564         desc->noautoenable = (iflags & IRQF_NOAUTOEN) != 0;
 565         spin_unlock_irqrestore(&irq_controller_lock, flags);
 566 }
 567
 568 int setup_irq(unsigned int irq, struct irqaction *new)
 569 {
 570         int shared = 0;
 571         struct irqaction *old, **p;
 572         unsigned long flags;
 573         struct irqdesc *desc;
 574
 575         /*
 576          * Some drivers like serial.c use request_irq() heavily,
 577          * so we have to be careful not to interfere with a
 578          * running system.
 579          */
 580         if (new->flags & SA_SAMPLE_RANDOM) {
 581                 /*
 582                  * This function might sleep, we want to call it first,
 583                  * outside of the atomic block.
 584                  * Yes, this might clear the entropy pool if the wrong
 585                  * driver is attempted to be loaded, without actually
 586                  * installing a new handler, but is this really a problem,
 587                  * only the sysadmin is able to do this.
 588                  */
 589                 rand_initialize_irq(irq);
 590         }
 591
 592         /*
 593          * The following block of code has to be executed atomically
 594          */
 595         desc = irq_desc + irq;
 596         spin_lock_irqsave(&irq_controller_lock, flags);
 597         p = &desc->action;
 598         if ((old = *p) != NULL) {
 599                 /* Can't share interrupts unless both agree to */
 600                 if (!(old->flags & new->flags & SA_SHIRQ)) {
 601                         spin_unlock_irqrestore(&irq_controller_lock, flags);
 602                         return -EBUSY;
 603                 }
 604
 605                 /* add new interrupt at end of irq queue */
 606                 do {
 607                         p = &old->next;
 608                         old = *p;
 609                 } while (old);
 610                 shared = 1;
 611         }
 612
 613         *p = new;
 614
 615         if (!shared) {
 616                 desc->probing = 0;
 617                 desc->running = 0;
 618                 desc->pending = 0;
 619                 desc->disable_depth = 1;
 620                 if (!desc->noautoenable) {
 621                         desc->disable_depth = 0;
 622                         desc->chip->unmask(irq);
 623                 }
 624         }
 625
 626         spin_unlock_irqrestore(&irq_controller_lock, flags);
 627         return 0;
 628 }
 629
 630 /**
 631  *      request_irq - allocate an interrupt line
 632  *      @irq: Interrupt line to allocate
 633  *      @handler: Function to be called when the IRQ occurs
 634  *      @irqflags: Interrupt type flags
 635  *      @devname: An ascii name for the claiming device
 636  *      @dev_id: A cookie passed back to the handler function
 637  *
 638  *      This call allocates interrupt resources and enables the
 639  *      interrupt line and IRQ handling. From the point this
 640  *      call is made your handler function may be invoked. Since
 641  *      your handler function must clear any interrupt the board
 642  *      raises, you must take care both to initialise your hardware
 643  *      and to set up the interrupt handler in the right order.
 644  *
 645  *      Dev_id must be globally unique. Normally the address of the
 646  *      device data structure is used as the cookie. Since the handler
 647  *      receives this value it makes sense to use it.
 648  *
 649  *      If your interrupt is shared you must pass a non NULL dev_id
 650  *      as this is required when freeing the interrupt.
 651  *
 652  *      Flags:
 653  *
 654  *      SA_SHIRQ                Interrupt is shared
 655  *
 656  *      SA_INTERRUPT            Disable local interrupts while processing
 657  *
 658  *      SA_SAMPLE_RANDOM        The interrupt can be used for entropy
 659  *
 660  */
 661 int request_irq(unsigned int irq, irqreturn_t (*handler)(int, void *, struct pt_regs *),
 662                  unsigned long irq_flags, const char * devname, void *dev_id)
 663 {
 664         unsigned long retval;
 665         struct irqaction *action;
 666
 667         if (irq >= NR_IRQS || !irq_desc[irq].valid || !handler ||
 668             (irq_flags & SA_SHIRQ && !dev_id))
 669                 return -EINVAL;
 670
 671         action = (struct irqaction *)kmalloc(sizeof(struct irqaction), GFP_KERNEL);
 672         if (!action)
 673                 return -ENOMEM;
 674
 675         action->handler = handler;
 676         action->flags = irq_flags;
 677         action->mask = 0;
 678         action->name = devname;
 679         action->next = NULL;
 680         action->dev_id = dev_id;
 681
 682         retval = setup_irq(irq, action);
 683
 684         if (retval)
 685                 kfree(action);
 686         return retval;
 687 }
 688
 689 EXPORT_SYMBOL(request_irq);
 690
 691 /**
 692  *      free_irq - free an interrupt
 693  *      @irq: Interrupt line to free
 694  *      @dev_id: Device identity to free
 695  *
 696  *      Remove an interrupt handler. The handler is removed and if the
 697  *      interrupt line is no longer in use by any driver it is disabled.
 698  *      On a shared IRQ the caller must ensure the interrupt is disabled
 699  *      on the card it drives before calling this function.
 700  *
 701  *      This function must not be called from interrupt context.
 702  */
 703 void free_irq(unsigned int irq, void *dev_id)
 704 {
 705         struct irqaction * action, **p;
 706         unsigned long flags;
 707
 708         if (irq >= NR_IRQS || !irq_desc[irq].valid) {
 709                 printk(KERN_ERR "Trying to free IRQ%d\n",irq);
 710                 dump_stack();
 711                 return;
 712         }
 713
 714         spin_lock_irqsave(&irq_controller_lock, flags);
 715         for (p = &irq_desc[irq].action; (action = *p) != NULL; p = &action->next) {
 716                 if (action->dev_id != dev_id)
 717                         continue;
 718
 719                 /* Found it - now free it */
 720                 *p = action->next;
 721                 break;
 722         }
 723         spin_unlock_irqrestore(&irq_controller_lock, flags);
 724
 725         if (!action) {
 726                 printk(KERN_ERR "Trying to free free IRQ%d\n",irq);
 727                 dump_stack();
 728         } else {
 729                 synchronize_irq(irq);
 730                 kfree(action);
 731         }
 732 }
 733
 734 EXPORT_SYMBOL(free_irq);
 735
 736 static DECLARE_MUTEX(probe_sem);
 737
 738 /* Start the interrupt probing.  Unlike other architectures,
 739  * we don't return a mask of interrupts from probe_irq_on,
 740  * but return the number of interrupts enabled for the probe.
 741  * The interrupts which have been enabled for probing is
 742  * instead recorded in the irq_desc structure.
 743  */
 744 unsigned long probe_irq_on(void)
 745 {
 746         unsigned int i, irqs = 0;
 747         unsigned long delay;
 748
 749         down(&probe_sem);
 750
 751         /*
 752          * first snaffle up any unassigned but
 753          * probe-able interrupts
 754          */
 755         spin_lock_irq(&irq_controller_lock);
 756         for (i = 0; i < NR_IRQS; i++) {
 757                 if (!irq_desc[i].probe_ok || irq_desc[i].action)
 758                         continue;
 759
 760                 irq_desc[i].probing = 1;
 761                 irq_desc[i].triggered = 0;
 762                 if (irq_desc[i].chip->type)
 763                         irq_desc[i].chip->type(i, IRQT_PROBE);
 764                 irq_desc[i].chip->unmask(i);
 765                 irqs += 1;
 766         }
 767         spin_unlock_irq(&irq_controller_lock);
 768
 769         /*
 770          * wait for spurious interrupts to mask themselves out again
 771          */
 772         for (delay = jiffies + HZ/10; time_before(jiffies, delay); )
 773                 /* min 100ms delay */;
 774
 775         /*
 776          * now filter out any obviously spurious interrupts
 777          */
 778         spin_lock_irq(&irq_controller_lock);
 779         for (i = 0; i < NR_IRQS; i++) {
 780                 if (irq_desc[i].probing && irq_desc[i].triggered) {
 781                         irq_desc[i].probing = 0;
 782                         irqs -= 1;
 783                 }
 784         }
 785         spin_unlock_irq(&irq_controller_lock);
 786
 787         return irqs;
 788 }
 789
 790 EXPORT_SYMBOL(probe_irq_on);
 791
 792 unsigned int probe_irq_mask(unsigned long irqs)
 793 {
 794         unsigned int mask = 0, i;
 795
 796         spin_lock_irq(&irq_controller_lock);
 797         for (i = 0; i < 16 && i < NR_IRQS; i++)
 798                 if (irq_desc[i].probing && irq_desc[i].triggered)
 799                         mask |= 1 << i;
 800         spin_unlock_irq(&irq_controller_lock);
 801
 802         up(&probe_sem);
 803
 804         return mask;
 805 }
 806 EXPORT_SYMBOL(probe_irq_mask);
 807
 808 /*
 809  * Possible return values:
 810  *  >= 0 - interrupt number
 811  *    -1 - no interrupt/many interrupts
 812  */
 813 int probe_irq_off(unsigned long irqs)
 814 {
 815         unsigned int i;
 816         int irq_found = NO_IRQ;
 817
 818         /*
 819          * look at the interrupts, and find exactly one
 820          * that we were probing has been triggered
 821          */
 822         spin_lock_irq(&irq_controller_lock);
 823         for (i = 0; i < NR_IRQS; i++) {
 824                 if (irq_desc[i].probing &&
 825                     irq_desc[i].triggered) {
 826                         if (irq_found != NO_IRQ) {
 827                                 irq_found = NO_IRQ;
 828                                 goto out;
 829                         }
 830                         irq_found = i;
 831                 }
 832         }
 833
 834         if (irq_found == -1)
 835                 irq_found = NO_IRQ;
 836 out:
 837         spin_unlock_irq(&irq_controller_lock);
 838
 839         up(&probe_sem);
 840
 841         return irq_found;
 842 }
 843
 844 EXPORT_SYMBOL(probe_irq_off);
 845
 846 void __init init_irq_proc(void)
 847 {
 848 }
 849
 850 void __init init_IRQ(void)
 851 {
 852         struct irqdesc *desc;
 853         extern void init_dma(void);
 854         int irq;
 855
 856         for (irq = 0, desc = irq_desc; irq < NR_IRQS; irq++, desc++) {
 857                 *desc = bad_irq_desc;
 858                 INIT_LIST_HEAD(&desc->pend);
 859         }
 860
 861         init_arch_irq();
 862         init_dma();
 863 }