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   1 /*
   2  * linux/kernel/irq/manage.c
   3  *
   4  * Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
   5  * Copyright (C) 2005-2006 Thomas Gleixner
   6  *
   7  * This file contains driver APIs to the irq subsystem.
   8  */
   9
  10 #include <linux/irq.h>
  11 #include <linux/module.h>
  12 #include <linux/random.h>
  13 #include <linux/interrupt.h>
  14 #include <linux/slab.h>
  15
  16 #include "internals.h"
  17
  18 #ifdef CONFIG_SMP
  19 cpumask_var_t irq_default_affinity;
  20
  21 static int init_irq_default_affinity(void)
  22 {
  23         alloc_cpumask_var(&irq_default_affinity, GFP_KERNEL);
  24         cpumask_setall(irq_default_affinity);
  25         return 0;
  26 }
  27 core_initcall(init_irq_default_affinity);
  28
  29 /**
  30  *      synchronize_irq - wait for pending IRQ handlers (on other CPUs)
  31  *      @irq: interrupt number to wait for
  32  *
  33  *      This function waits for any pending IRQ handlers for this interrupt
  34  *      to complete before returning. If you use this function while
  35  *      holding a resource the IRQ handler may need you will deadlock.
  36  *
  37  *      This function may be called - with care - from IRQ context.
  38  */
  39 void synchronize_irq(unsigned int irq)
  40 {
  41         struct irq_desc *desc = irq_to_desc(irq);
  42         unsigned int status;
  43
  44         if (!desc)
  45                 return;
  46
  47         do {
  48                 unsigned long flags;
  49
  50                 /*
  51                  * Wait until we're out of the critical section.  This might
  52                  * give the wrong answer due to the lack of memory barriers.
  53                  */
  54                 while (desc->status & IRQ_INPROGRESS)
  55                         cpu_relax();
  56
  57                 /* Ok, that indicated we're done: double-check carefully. */
  58                 spin_lock_irqsave(&desc->lock, flags);
  59                 status = desc->status;
  60                 spin_unlock_irqrestore(&desc->lock, flags);
  61
  62                 /* Oops, that failed? */
  63         } while (status & IRQ_INPROGRESS);
  64 }
  65 EXPORT_SYMBOL(synchronize_irq);
  66
  67 /**
  68  *      irq_can_set_affinity - Check if the affinity of a given irq can be set
  69  *      @irq:           Interrupt to check
  70  *
  71  */
  72 int irq_can_set_affinity(unsigned int irq)
  73 {
  74         struct irq_desc *desc = irq_to_desc(irq);
  75
  76         if (CHECK_IRQ_PER_CPU(desc->status) || !desc->chip ||
  77             !desc->chip->set_affinity)
  78                 return 0;
  79
  80         return 1;
  81 }
  82
  83 /**
  84  *      irq_set_affinity - Set the irq affinity of a given irq
  85  *      @irq:           Interrupt to set affinity
  86  *      @cpumask:       cpumask
  87  *
  88  */
  89 int irq_set_affinity(unsigned int irq, const struct cpumask *cpumask)
  90 {
  91         struct irq_desc *desc = irq_to_desc(irq);
  92         unsigned long flags;
  93
  94         if (!desc->chip->set_affinity)
  95                 return -EINVAL;
  96
  97         spin_lock_irqsave(&desc->lock, flags);
  98
  99 #ifdef CONFIG_GENERIC_PENDING_IRQ
 100         if (desc->status & IRQ_MOVE_PCNTXT || desc->status & IRQ_DISABLED) {
 101                 cpumask_copy(&desc->affinity, cpumask);
 102                 desc->chip->set_affinity(irq, cpumask);
 103         } else {
 104                 desc->status |= IRQ_MOVE_PENDING;
 105                 cpumask_copy(&desc->pending_mask, cpumask);
 106         }
 107 #else
 108         cpumask_copy(&desc->affinity, cpumask);
 109         desc->chip->set_affinity(irq, cpumask);
 110 #endif
 111         desc->status |= IRQ_AFFINITY_SET;
 112         spin_unlock_irqrestore(&desc->lock, flags);
 113         return 0;
 114 }
 115
 116 #ifndef CONFIG_AUTO_IRQ_AFFINITY
 117 /*
 118  * Generic version of the affinity autoselector.
 119  */
 120 int do_irq_select_affinity(unsigned int irq, struct irq_desc *desc)
 121 {
 122         if (!irq_can_set_affinity(irq))
 123                 return 0;
 124
 125         /*
 126          * Preserve an userspace affinity setup, but make sure that
 127          * one of the targets is online.
 128          */
 129         if (desc->status & (IRQ_AFFINITY_SET | IRQ_NO_BALANCING)) {
 130                 if (cpumask_any_and(&desc->affinity, cpu_online_mask)
 131                     < nr_cpu_ids)
 132                         goto set_affinity;
 133                 else
 134                         desc->status &= ~IRQ_AFFINITY_SET;
 135         }
 136
 137         cpumask_and(&desc->affinity, cpu_online_mask, irq_default_affinity);
 138 set_affinity:
 139         desc->chip->set_affinity(irq, &desc->affinity);
 140
 141         return 0;
 142 }
 143 #else
 144 static inline int do_irq_select_affinity(unsigned int irq, struct irq_desc *d)
 145 {
 146         return irq_select_affinity(irq);
 147 }
 148 #endif
 149
 150 /*
 151  * Called when affinity is set via /proc/irq
 152  */
 153 int irq_select_affinity_usr(unsigned int irq)
 154 {
 155         struct irq_desc *desc = irq_to_desc(irq);
 156         unsigned long flags;
 157         int ret;
 158
 159         spin_lock_irqsave(&desc->lock, flags);
 160         ret = do_irq_select_affinity(irq, desc);
 161         spin_unlock_irqrestore(&desc->lock, flags);
 162
 163         return ret;
 164 }
 165
 166 #else
 167 static inline int do_irq_select_affinity(int irq, struct irq_desc *desc)
 168 {
 169         return 0;
 170 }
 171 #endif
 172
 173 /**
 174  *      disable_irq_nosync - disable an irq without waiting
 175  *      @irq: Interrupt to disable
 176  *
 177  *      Disable the selected interrupt line.  Disables and Enables are
 178  *      nested.
 179  *      Unlike disable_irq(), this function does not ensure existing
 180  *      instances of the IRQ handler have completed before returning.
 181  *
 182  *      This function may be called from IRQ context.
 183  */
 184 void disable_irq_nosync(unsigned int irq)
 185 {
 186         struct irq_desc *desc = irq_to_desc(irq);
 187         unsigned long flags;
 188
 189         if (!desc)
 190                 return;
 191
 192         spin_lock_irqsave(&desc->lock, flags);
 193         if (!desc->depth++) {
 194                 desc->status |= IRQ_DISABLED;
 195                 desc->chip->disable(irq);
 196         }
 197         spin_unlock_irqrestore(&desc->lock, flags);
 198 }
 199 EXPORT_SYMBOL(disable_irq_nosync);
 200
 201 /**
 202  *      disable_irq - disable an irq and wait for completion
 203  *      @irq: Interrupt to disable
 204  *
 205  *      Disable the selected interrupt line.  Enables and Disables are
 206  *      nested.
 207  *      This function waits for any pending IRQ handlers for this interrupt
 208  *      to complete before returning. If you use this function while
 209  *      holding a resource the IRQ handler may need you will deadlock.
 210  *
 211  *      This function may be called - with care - from IRQ context.
 212  */
 213 void disable_irq(unsigned int irq)
 214 {
 215         struct irq_desc *desc = irq_to_desc(irq);
 216
 217         if (!desc)
 218                 return;
 219
 220         disable_irq_nosync(irq);
 221         if (desc->action)
 222                 synchronize_irq(irq);
 223 }
 224 EXPORT_SYMBOL(disable_irq);
 225
 226 static void __enable_irq(struct irq_desc *desc, unsigned int irq)
 227 {
 228         switch (desc->depth) {
 229         case 0:
 230                 WARN(1, KERN_WARNING "Unbalanced enable for IRQ %d\n", irq);
 231                 break;
 232         case 1: {
 233                 unsigned int status = desc->status & ~IRQ_DISABLED;
 234
 235                 /* Prevent probing on this irq: */
 236                 desc->status = status | IRQ_NOPROBE;
 237                 check_irq_resend(desc, irq);
 238                 /* fall-through */
 239         }
 240         default:
 241                 desc->depth--;
 242         }
 243 }
 244
 245 /**
 246  *      enable_irq - enable handling of an irq
 247  *      @irq: Interrupt to enable
 248  *
 249  *      Undoes the effect of one call to disable_irq().  If this
 250  *      matches the last disable, processing of interrupts on this
 251  *      IRQ line is re-enabled.
 252  *
 253  *      This function may be called from IRQ context.
 254  */
 255 void enable_irq(unsigned int irq)
 256 {
 257         struct irq_desc *desc = irq_to_desc(irq);
 258         unsigned long flags;
 259
 260         if (!desc)
 261                 return;
 262
 263         spin_lock_irqsave(&desc->lock, flags);
 264         __enable_irq(desc, irq);
 265         spin_unlock_irqrestore(&desc->lock, flags);
 266 }
 267 EXPORT_SYMBOL(enable_irq);
 268
 269 static int set_irq_wake_real(unsigned int irq, unsigned int on)
 270 {
 271         struct irq_desc *desc = irq_to_desc(irq);
 272         int ret = -ENXIO;
 273
 274         if (desc->chip->set_wake)
 275                 ret = desc->chip->set_wake(irq, on);
 276
 277         return ret;
 278 }
 279
 280 /**
 281  *      set_irq_wake - control irq power management wakeup
 282  *      @irq:   interrupt to control
 283  *      @on:    enable/disable power management wakeup
 284  *
 285  *      Enable/disable power management wakeup mode, which is
 286  *      disabled by default.  Enables and disables must match,
 287  *      just as they match for non-wakeup mode support.
 288  *
 289  *      Wakeup mode lets this IRQ wake the system from sleep
 290  *      states like "suspend to RAM".
 291  */
 292 int set_irq_wake(unsigned int irq, unsigned int on)
 293 {
 294         struct irq_desc *desc = irq_to_desc(irq);
 295         unsigned long flags;
 296         int ret = 0;
 297
 298         /* wakeup-capable irqs can be shared between drivers that
 299          * don't need to have the same sleep mode behaviors.
 300          */
 301         spin_lock_irqsave(&desc->lock, flags);
 302         if (on) {
 303                 if (desc->wake_depth++ == 0) {
 304                         ret = set_irq_wake_real(irq, on);
 305                         if (ret)
 306                                 desc->wake_depth = 0;
 307                         else
 308                                 desc->status |= IRQ_WAKEUP;
 309                 }
 310         } else {
 311                 if (desc->wake_depth == 0) {
 312                         WARN(1, "Unbalanced IRQ %d wake disable\n", irq);
 313                 } else if (--desc->wake_depth == 0) {
 314                         ret = set_irq_wake_real(irq, on);
 315                         if (ret)
 316                                 desc->wake_depth = 1;
 317                         else
 318                                 desc->status &= ~IRQ_WAKEUP;
 319                 }
 320         }
 321
 322         spin_unlock_irqrestore(&desc->lock, flags);
 323         return ret;
 324 }
 325 EXPORT_SYMBOL(set_irq_wake);
 326
 327 /*
 328  * Internal function that tells the architecture code whether a
 329  * particular irq has been exclusively allocated or is available
 330  * for driver use.
 331  */
 332 int can_request_irq(unsigned int irq, unsigned long irqflags)
 333 {
 334         struct irq_desc *desc = irq_to_desc(irq);
 335         struct irqaction *action;
 336
 337         if (!desc)
 338                 return 0;
 339
 340         if (desc->status & IRQ_NOREQUEST)
 341                 return 0;
 342
 343         action = desc->action;
 344         if (action)
 345                 if (irqflags & action->flags & IRQF_SHARED)
 346                         action = NULL;
 347
 348         return !action;
 349 }
 350
 351 void compat_irq_chip_set_default_handler(struct irq_desc *desc)
 352 {
 353         /*
 354          * If the architecture still has not overriden
 355          * the flow handler then zap the default. This
 356          * should catch incorrect flow-type setting.
 357          */
 358         if (desc->handle_irq == &handle_bad_irq)
 359                 desc->handle_irq = NULL;
 360 }
 361
 362 int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
 363                 unsigned long flags)
 364 {
 365         int ret;
 366         struct irq_chip *chip = desc->chip;
 367
 368         if (!chip || !chip->set_type) {
 369                 /*
 370                  * IRQF_TRIGGER_* but the PIC does not support multiple
 371                  * flow-types?
 372                  */
 373                 pr_debug("No set_type function for IRQ %d (%s)\n", irq,
 374                                 chip ? (chip->name ? : "unknown") : "unknown");
 375                 return 0;
 376         }
 377
 378         /* caller masked out all except trigger mode flags */
 379         ret = chip->set_type(irq, flags);
 380
 381         if (ret)
 382                 pr_err("setting trigger mode %d for irq %u failed (%pF)\n",
 383                                 (int)flags, irq, chip->set_type);
 384         else {
 385                 if (flags & (IRQ_TYPE_LEVEL_LOW | IRQ_TYPE_LEVEL_HIGH))
 386                         flags |= IRQ_LEVEL;
 387                 /* note that IRQF_TRIGGER_MASK == IRQ_TYPE_SENSE_MASK */
 388                 desc->status &= ~(IRQ_LEVEL | IRQ_TYPE_SENSE_MASK);
 389                 desc->status |= flags;
 390         }
 391
 392         return ret;
 393 }
 394
 395 /*
 396  * Internal function to register an irqaction - typically used to
 397  * allocate special interrupts that are part of the architecture.
 398  */
 399 static int
 400 __setup_irq(unsigned int irq, struct irq_desc * desc, struct irqaction *new)
 401 {
 402         struct irqaction *old, **p;
 403         const char *old_name = NULL;
 404         unsigned long flags;
 405         int shared = 0;
 406         int ret;
 407
 408         if (!desc)
 409                 return -EINVAL;
 410
 411         if (desc->chip == &no_irq_chip)
 412                 return -ENOSYS;
 413         /*
 414          * Some drivers like serial.c use request_irq() heavily,
 415          * so we have to be careful not to interfere with a
 416          * running system.
 417          */
 418         if (new->flags & IRQF_SAMPLE_RANDOM) {
 419                 /*
 420                  * This function might sleep, we want to call it first,
 421                  * outside of the atomic block.
 422                  * Yes, this might clear the entropy pool if the wrong
 423                  * driver is attempted to be loaded, without actually
 424                  * installing a new handler, but is this really a problem,
 425                  * only the sysadmin is able to do this.
 426                  */
 427                 rand_initialize_irq(irq);
 428         }
 429
 430         /*
 431          * The following block of code has to be executed atomically
 432          */
 433         spin_lock_irqsave(&desc->lock, flags);
 434         p = &desc->action;
 435         old = *p;
 436         if (old) {
 437                 /*
 438                  * Can't share interrupts unless both agree to and are
 439                  * the same type (level, edge, polarity). So both flag
 440                  * fields must have IRQF_SHARED set and the bits which
 441                  * set the trigger type must match.
 442                  */
 443                 if (!((old->flags & new->flags) & IRQF_SHARED) ||
 444                     ((old->flags ^ new->flags) & IRQF_TRIGGER_MASK)) {
 445                         old_name = old->name;
 446                         goto mismatch;
 447                 }
 448
 449 #if defined(CONFIG_IRQ_PER_CPU)
 450                 /* All handlers must agree on per-cpuness */
 451                 if ((old->flags & IRQF_PERCPU) !=
 452                     (new->flags & IRQF_PERCPU))
 453                         goto mismatch;
 454 #endif
 455
 456                 /* add new interrupt at end of irq queue */
 457                 do {
 458                         p = &old->next;
 459                         old = *p;
 460                 } while (old);
 461                 shared = 1;
 462         }
 463
 464         if (!shared) {
 465                 irq_chip_set_defaults(desc->chip);
 466
 467                 /* Setup the type (level, edge polarity) if configured: */
 468                 if (new->flags & IRQF_TRIGGER_MASK) {
 469                         ret = __irq_set_trigger(desc, irq,
 470                                         new->flags & IRQF_TRIGGER_MASK);
 471
 472                         if (ret) {
 473                                 spin_unlock_irqrestore(&desc->lock, flags);
 474                                 return ret;
 475                         }
 476                 } else
 477                         compat_irq_chip_set_default_handler(desc);
 478 #if defined(CONFIG_IRQ_PER_CPU)
 479                 if (new->flags & IRQF_PERCPU)
 480                         desc->status |= IRQ_PER_CPU;
 481 #endif
 482
 483                 desc->status &= ~(IRQ_AUTODETECT | IRQ_WAITING |
 484                                   IRQ_INPROGRESS | IRQ_SPURIOUS_DISABLED);
 485
 486                 if (!(desc->status & IRQ_NOAUTOEN)) {
 487                         desc->depth = 0;
 488                         desc->status &= ~IRQ_DISABLED;
 489                         desc->chip->startup(irq);
 490                 } else
 491                         /* Undo nested disables: */
 492                         desc->depth = 1;
 493
 494                 /* Exclude IRQ from balancing if requested */
 495                 if (new->flags & IRQF_NOBALANCING)
 496                         desc->status |= IRQ_NO_BALANCING;
 497
 498                 /* Set default affinity mask once everything is setup */
 499                 do_irq_select_affinity(irq, desc);
 500
 501         } else if ((new->flags & IRQF_TRIGGER_MASK)
 502                         && (new->flags & IRQF_TRIGGER_MASK)
 503                                 != (desc->status & IRQ_TYPE_SENSE_MASK)) {
 504                 /* hope the handler works with the actual trigger mode... */
 505                 pr_warning("IRQ %d uses trigger mode %d; requested %d\n",
 506                                 irq, (int)(desc->status & IRQ_TYPE_SENSE_MASK),
 507                                 (int)(new->flags & IRQF_TRIGGER_MASK));
 508         }
 509
 510         *p = new;
 511
 512         /* Reset broken irq detection when installing new handler */
 513         desc->irq_count = 0;
 514         desc->irqs_unhandled = 0;
 515
 516         /*
 517          * Check whether we disabled the irq via the spurious handler
 518          * before. Reenable it and give it another chance.
 519          */
 520         if (shared && (desc->status & IRQ_SPURIOUS_DISABLED)) {
 521                 desc->status &= ~IRQ_SPURIOUS_DISABLED;
 522                 __enable_irq(desc, irq);
 523         }
 524
 525         spin_unlock_irqrestore(&desc->lock, flags);
 526
 527         new->irq = irq;
 528         register_irq_proc(irq, desc);
 529         new->dir = NULL;
 530         register_handler_proc(irq, new);
 531
 532         return 0;
 533
 534 mismatch:
 535 #ifdef CONFIG_DEBUG_SHIRQ
 536         if (!(new->flags & IRQF_PROBE_SHARED)) {
 537                 printk(KERN_ERR "IRQ handler type mismatch for IRQ %d\n", irq);
 538                 if (old_name)
 539                         printk(KERN_ERR "current handler: %s\n", old_name);
 540                 dump_stack();
 541         }
 542 #endif
 543         spin_unlock_irqrestore(&desc->lock, flags);
 544         return -EBUSY;
 545 }
 546
 547 /**
 548  *      setup_irq - setup an interrupt
 549  *      @irq: Interrupt line to setup
 550  *      @act: irqaction for the interrupt
 551  *
 552  * Used to statically setup interrupts in the early boot process.
 553  */
 554 int setup_irq(unsigned int irq, struct irqaction *act)
 555 {
 556         struct irq_desc *desc = irq_to_desc(irq);
 557
 558         return __setup_irq(irq, desc, act);
 559 }
 560
 561 /**
 562  *      free_irq - free an interrupt
 563  *      @irq: Interrupt line to free
 564  *      @dev_id: Device identity to free
 565  *
 566  *      Remove an interrupt handler. The handler is removed and if the
 567  *      interrupt line is no longer in use by any driver it is disabled.
 568  *      On a shared IRQ the caller must ensure the interrupt is disabled
 569  *      on the card it drives before calling this function. The function
 570  *      does not return until any executing interrupts for this IRQ
 571  *      have completed.
 572  *
 573  *      This function must not be called from interrupt context.
 574  */
 575 void free_irq(unsigned int irq, void *dev_id)
 576 {
 577         struct irq_desc *desc = irq_to_desc(irq);
 578         struct irqaction **p;
 579         unsigned long flags;
 580
 581         WARN_ON(in_interrupt());
 582
 583         if (!desc)
 584                 return;
 585
 586         spin_lock_irqsave(&desc->lock, flags);
 587         p = &desc->action;
 588         for (;;) {
 589                 struct irqaction *action = *p;
 590
 591                 if (action) {
 592                         struct irqaction **pp = p;
 593
 594                         p = &action->next;
 595                         if (action->dev_id != dev_id)
 596                                 continue;
 597
 598                         /* Found it - now remove it from the list of entries */
 599                         *pp = action->next;
 600
 601                         /* Currently used only by UML, might disappear one day.*/
 602 #ifdef CONFIG_IRQ_RELEASE_METHOD
 603                         if (desc->chip->release)
 604                                 desc->chip->release(irq, dev_id);
 605 #endif
 606
 607                         if (!desc->action) {
 608                                 desc->status |= IRQ_DISABLED;
 609                                 if (desc->chip->shutdown)
 610                                         desc->chip->shutdown(irq);
 611                                 else
 612                                         desc->chip->disable(irq);
 613                         }
 614                         spin_unlock_irqrestore(&desc->lock, flags);
 615                         unregister_handler_proc(irq, action);
 616
 617                         /* Make sure it's not being used on another CPU */
 618                         synchronize_irq(irq);
 619 #ifdef CONFIG_DEBUG_SHIRQ
 620                         /*
 621                          * It's a shared IRQ -- the driver ought to be
 622                          * prepared for it to happen even now it's
 623                          * being freed, so let's make sure....  We do
 624                          * this after actually deregistering it, to
 625                          * make sure that a 'real' IRQ doesn't run in
 626                          * parallel with our fake
 627                          */
 628                         if (action->flags & IRQF_SHARED) {
 629                                 local_irq_save(flags);
 630                                 action->handler(irq, dev_id);
 631                                 local_irq_restore(flags);
 632                         }
 633 #endif
 634                         kfree(action);
 635                         return;
 636                 }
 637                 printk(KERN_ERR "Trying to free already-free IRQ %d\n", irq);
 638 #ifdef CONFIG_DEBUG_SHIRQ
 639                 dump_stack();
 640 #endif
 641                 spin_unlock_irqrestore(&desc->lock, flags);
 642                 return;
 643         }
 644 }
 645 EXPORT_SYMBOL(free_irq);
 646
 647 /**
 648  *      request_irq - allocate an interrupt line
 649  *      @irq: Interrupt line to allocate
 650  *      @handler: Function to be called when the IRQ occurs
 651  *      @irqflags: Interrupt type flags
 652  *      @devname: An ascii name for the claiming device
 653  *      @dev_id: A cookie passed back to the handler function
 654  *
 655  *      This call allocates interrupt resources and enables the
 656  *      interrupt line and IRQ handling. From the point this
 657  *      call is made your handler function may be invoked. Since
 658  *      your handler function must clear any interrupt the board
 659  *      raises, you must take care both to initialise your hardware
 660  *      and to set up the interrupt handler in the right order.
 661  *
 662  *      Dev_id must be globally unique. Normally the address of the
 663  *      device data structure is used as the cookie. Since the handler
 664  *      receives this value it makes sense to use it.
 665  *
 666  *      If your interrupt is shared you must pass a non NULL dev_id
 667  *      as this is required when freeing the interrupt.
 668  *
 669  *      Flags:
 670  *
 671  *      IRQF_SHARED             Interrupt is shared
 672  *      IRQF_DISABLED   Disable local interrupts while processing
 673  *      IRQF_SAMPLE_RANDOM      The interrupt can be used for entropy
 674  *      IRQF_TRIGGER_*          Specify active edge(s) or level
 675  *
 676  */
 677 int request_irq(unsigned int irq, irq_handler_t handler,
 678                 unsigned long irqflags, const char *devname, void *dev_id)
 679 {
 680         struct irqaction *action;
 681         struct irq_desc *desc;
 682         int retval;
 683
 684         /*
 685          * handle_IRQ_event() always ignores IRQF_DISABLED except for
 686          * the _first_ irqaction (sigh).  That can cause oopsing, but
 687          * the behavior is classified as "will not fix" so we need to
 688          * start nudging drivers away from using that idiom.
 689          */
 690         if ((irqflags & (IRQF_SHARED|IRQF_DISABLED))
 691                         == (IRQF_SHARED|IRQF_DISABLED))
 692                 pr_warning("IRQ %d/%s: IRQF_DISABLED is not "
 693                                 "guaranteed on shared IRQs\n",
 694                                 irq, devname);
 695
 696 #ifdef CONFIG_LOCKDEP
 697         /*
 698          * Lockdep wants atomic interrupt handlers:
 699          */
 700         irqflags |= IRQF_DISABLED;
 701 #endif
 702         /*
 703          * Sanity-check: shared interrupts must pass in a real dev-ID,
 704          * otherwise we'll have trouble later trying to figure out
 705          * which interrupt is which (messes up the interrupt freeing
 706          * logic etc).
 707          */
 708         if ((irqflags & IRQF_SHARED) && !dev_id)
 709                 return -EINVAL;
 710
 711         desc = irq_to_desc(irq);
 712         if (!desc)
 713                 return -EINVAL;
 714
 715         if (desc->status & IRQ_NOREQUEST)
 716                 return -EINVAL;
 717         if (!handler)
 718                 return -EINVAL;
 719
 720         action = kmalloc(sizeof(struct irqaction), GFP_ATOMIC);
 721         if (!action)
 722                 return -ENOMEM;
 723
 724         action->handler = handler;
 725         action->flags = irqflags;
 726         cpus_clear(action->mask);
 727         action->name = devname;
 728         action->next = NULL;
 729         action->dev_id = dev_id;
 730
 731         retval = __setup_irq(irq, desc, action);
 732         if (retval)
 733                 kfree(action);
 734
 735 #ifdef CONFIG_DEBUG_SHIRQ
 736         if (irqflags & IRQF_SHARED) {
 737                 /*
 738                  * It's a shared IRQ -- the driver ought to be prepared for it
 739                  * to happen immediately, so let's make sure....
 740                  * We disable the irq to make sure that a 'real' IRQ doesn't
 741                  * run in parallel with our fake.
 742                  */
 743                 unsigned long flags;
 744
 745                 disable_irq(irq);
 746                 local_irq_save(flags);
 747
 748                 handler(irq, dev_id);
 749
 750                 local_irq_restore(flags);
 751                 enable_irq(irq);
 752         }
 753 #endif
 754         return retval;
 755 }
 756 EXPORT_SYMBOL(request_irq);