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