kernel/irq/manage.c

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