git.oblomov.eu Git - linux-2.6/blob - 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_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_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_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         set_pending_irq(irq, cpumask);
  93 #else
  94         desc->affinity = cpumask;
  95         desc->chip->set_affinity(irq, cpumask);
  96 #endif
  97         return 0;
  98 }
  99
 100 #ifndef CONFIG_AUTO_IRQ_AFFINITY
 101 /*
 102  * Generic version of the affinity autoselector.
 103  */
 104 int irq_select_affinity(unsigned int irq)
 105 {
 106         cpumask_t mask;
 107
 108         if (!irq_can_set_affinity(irq))
 109                 return 0;
 110
 111         cpus_and(mask, cpu_online_map, irq_default_affinity);
 112
 113         irq_desc[irq].affinity = mask;
 114         irq_desc[irq].chip->set_affinity(irq, mask);
 115
 116         set_balance_irq_affinity(irq, mask);
 117         return 0;
 118 }
 119 #endif
 120
 121 #endif
 122
 123 /**
 124  *      disable_irq_nosync - disable an irq without waiting
 125  *      @irq: Interrupt to disable
 126  *
 127  *      Disable the selected interrupt line.  Disables and Enables are
 128  *      nested.
 129  *      Unlike disable_irq(), this function does not ensure existing
 130  *      instances of the IRQ handler have completed before returning.
 131  *
 132  *      This function may be called from IRQ context.
 133  */
 134 void disable_irq_nosync(unsigned int irq)
 135 {
 136         struct irq_desc *desc = irq_desc + irq;
 137         unsigned long flags;
 138
 139         if (irq >= NR_IRQS)
 140                 return;
 141
 142         spin_lock_irqsave(&desc->lock, flags);
 143         if (!desc->depth++) {
 144                 desc->status |= IRQ_DISABLED;
 145                 desc->chip->disable(irq);
 146         }
 147         spin_unlock_irqrestore(&desc->lock, flags);
 148 }
 149 EXPORT_SYMBOL(disable_irq_nosync);
 150
 151 /**
 152  *      disable_irq - disable an irq and wait for completion
 153  *      @irq: Interrupt to disable
 154  *
 155  *      Disable the selected interrupt line.  Enables and Disables are
 156  *      nested.
 157  *      This function waits for any pending IRQ handlers for this interrupt
 158  *      to complete before returning. If you use this function while
 159  *      holding a resource the IRQ handler may need you will deadlock.
 160  *
 161  *      This function may be called - with care - from IRQ context.
 162  */
 163 void disable_irq(unsigned int irq)
 164 {
 165         struct irq_desc *desc = irq_desc + irq;
 166
 167         if (irq >= NR_IRQS)
 168                 return;
 169
 170         disable_irq_nosync(irq);
 171         if (desc->action)
 172                 synchronize_irq(irq);
 173 }
 174 EXPORT_SYMBOL(disable_irq);
 175
 176 static void __enable_irq(struct irq_desc *desc, unsigned int irq)
 177 {
 178         switch (desc->depth) {
 179         case 0:
 180                 WARN(1, KERN_WARNING "Unbalanced enable for IRQ %d\n", irq);
 181                 break;
 182         case 1: {
 183                 unsigned int status = desc->status & ~IRQ_DISABLED;
 184
 185                 /* Prevent probing on this irq: */
 186                 desc->status = status | IRQ_NOPROBE;
 187                 check_irq_resend(desc, irq);
 188                 /* fall-through */
 189         }
 190         default:
 191                 desc->depth--;
 192         }
 193 }
 194
 195 /**
 196  *      enable_irq - enable handling of an irq
 197  *      @irq: Interrupt to enable
 198  *
 199  *      Undoes the effect of one call to disable_irq().  If this
 200  *      matches the last disable, processing of interrupts on this
 201  *      IRQ line is re-enabled.
 202  *
 203  *      This function may be called from IRQ context.
 204  */
 205 void enable_irq(unsigned int irq)
 206 {
 207         struct irq_desc *desc = irq_desc + irq;
 208         unsigned long flags;
 209
 210         if (irq >= NR_IRQS)
 211                 return;
 212
 213         spin_lock_irqsave(&desc->lock, flags);
 214         __enable_irq(desc, irq);
 215         spin_unlock_irqrestore(&desc->lock, flags);
 216 }
 217 EXPORT_SYMBOL(enable_irq);
 218
 219 int set_irq_wake_real(unsigned int irq, unsigned int on)
 220 {
 221         struct irq_desc *desc = irq_desc + irq;
 222         int ret = -ENXIO;
 223
 224         if (desc->chip->set_wake)
 225                 ret = desc->chip->set_wake(irq, on);
 226
 227         return ret;
 228 }
 229
 230 /**
 231  *      set_irq_wake - control irq power management wakeup
 232  *      @irq:   interrupt to control
 233  *      @on:    enable/disable power management wakeup
 234  *
 235  *      Enable/disable power management wakeup mode, which is
 236  *      disabled by default.  Enables and disables must match,
 237  *      just as they match for non-wakeup mode support.
 238  *
 239  *      Wakeup mode lets this IRQ wake the system from sleep
 240  *      states like "suspend to RAM".
 241  */
 242 int set_irq_wake(unsigned int irq, unsigned int on)
 243 {
 244         struct irq_desc *desc = irq_desc + irq;
 245         unsigned long flags;
 246         int ret = 0;
 247
 248         /* wakeup-capable irqs can be shared between drivers that
 249          * don't need to have the same sleep mode behaviors.
 250          */
 251         spin_lock_irqsave(&desc->lock, flags);
 252         if (on) {
 253                 if (desc->wake_depth++ == 0) {
 254                         ret = set_irq_wake_real(irq, on);
 255                         if (ret)
 256                                 desc->wake_depth = 0;
 257                         else
 258                                 desc->status |= IRQ_WAKEUP;
 259                 }
 260         } else {
 261                 if (desc->wake_depth == 0) {
 262                         WARN(1, "Unbalanced IRQ %d wake disable\n", irq);
 263                 } else if (--desc->wake_depth == 0) {
 264                         ret = set_irq_wake_real(irq, on);
 265                         if (ret)
 266                                 desc->wake_depth = 1;
 267                         else
 268                                 desc->status &= ~IRQ_WAKEUP;
 269                 }
 270         }
 271
 272         spin_unlock_irqrestore(&desc->lock, flags);
 273         return ret;
 274 }
 275 EXPORT_SYMBOL(set_irq_wake);
 276
 277 /*
 278  * Internal function that tells the architecture code whether a
 279  * particular irq has been exclusively allocated or is available
 280  * for driver use.
 281  */
 282 int can_request_irq(unsigned int irq, unsigned long irqflags)
 283 {
 284         struct irqaction *action;
 285
 286         if (irq >= NR_IRQS || irq_desc[irq].status & IRQ_NOREQUEST)
 287                 return 0;
 288
 289         action = irq_desc[irq].action;
 290         if (action)
 291                 if (irqflags & action->flags & IRQF_SHARED)
 292                         action = NULL;
 293
 294         return !action;
 295 }
 296
 297 void compat_irq_chip_set_default_handler(struct irq_desc *desc)
 298 {
 299         /*
 300          * If the architecture still has not overriden
 301          * the flow handler then zap the default. This
 302          * should catch incorrect flow-type setting.
 303          */
 304         if (desc->handle_irq == &handle_bad_irq)
 305                 desc->handle_irq = NULL;
 306 }
 307
 308 static int __irq_set_trigger(struct irq_chip *chip, unsigned int irq,
 309                 unsigned long flags)
 310 {
 311         int ret;
 312
 313         if (!chip || !chip->set_type) {
 314                 /*
 315                  * IRQF_TRIGGER_* but the PIC does not support multiple
 316                  * flow-types?
 317                  */
 318                 pr_warning("No set_type function for IRQ %d (%s)\n", irq,
 319                                 chip ? (chip->name ? : "unknown") : "unknown");
 320                 return 0;
 321         }
 322
 323         ret = chip->set_type(irq, flags & IRQF_TRIGGER_MASK);
 324
 325         if (ret)
 326                 pr_err("setting flow type for irq %u failed (%pF)\n",
 327                                 irq, chip->set_type);
 328
 329         return ret;
 330 }
 331
 332 /*
 333  * Internal function to register an irqaction - typically used to
 334  * allocate special interrupts that are part of the architecture.
 335  */
 336 int setup_irq(unsigned int irq, struct irqaction *new)
 337 {
 338         struct irq_desc *desc = irq_desc + irq;
 339         struct irqaction *old, **p;
 340         const char *old_name = NULL;
 341         unsigned long flags;
 342         int shared = 0;
 343         int ret;
 344
 345         if (irq >= NR_IRQS)
 346                 return -EINVAL;
 347
 348         if (desc->chip == &no_irq_chip)
 349                 return -ENOSYS;
 350         /*
 351          * Some drivers like serial.c use request_irq() heavily,
 352          * so we have to be careful not to interfere with a
 353          * running system.
 354          */
 355         if (new->flags & IRQF_SAMPLE_RANDOM) {
 356                 /*
 357                  * This function might sleep, we want to call it first,
 358                  * outside of the atomic block.
 359                  * Yes, this might clear the entropy pool if the wrong
 360                  * driver is attempted to be loaded, without actually
 361                  * installing a new handler, but is this really a problem,
 362                  * only the sysadmin is able to do this.
 363                  */
 364                 rand_initialize_irq(irq);
 365         }
 366
 367         /*
 368          * The following block of code has to be executed atomically
 369          */
 370         spin_lock_irqsave(&desc->lock, flags);
 371         p = &desc->action;
 372         old = *p;
 373         if (old) {
 374                 /*
 375                  * Can't share interrupts unless both agree to and are
 376                  * the same type (level, edge, polarity). So both flag
 377                  * fields must have IRQF_SHARED set and the bits which
 378                  * set the trigger type must match.
 379                  */
 380                 if (!((old->flags & new->flags) & IRQF_SHARED) ||
 381                     ((old->flags ^ new->flags) & IRQF_TRIGGER_MASK)) {
 382                         old_name = old->name;
 383                         goto mismatch;
 384                 }
 385
 386 #if defined(CONFIG_IRQ_PER_CPU)
 387                 /* All handlers must agree on per-cpuness */
 388                 if ((old->flags & IRQF_PERCPU) !=
 389                     (new->flags & IRQF_PERCPU))
 390                         goto mismatch;
 391 #endif
 392
 393                 /* add new interrupt at end of irq queue */
 394                 do {
 395                         p = &old->next;
 396                         old = *p;
 397                 } while (old);
 398                 shared = 1;
 399         }
 400
 401         if (!shared) {
 402                 irq_chip_set_defaults(desc->chip);
 403
 404                 /* Setup the type (level, edge polarity) if configured: */
 405                 if (new->flags & IRQF_TRIGGER_MASK) {
 406                         ret = __irq_set_trigger(desc->chip, irq, new->flags);
 407
 408                         if (ret) {
 409                                 spin_unlock_irqrestore(&desc->lock, flags);
 410                                 return ret;
 411                         }
 412                 } else
 413                         compat_irq_chip_set_default_handler(desc);
 414 #if defined(CONFIG_IRQ_PER_CPU)
 415                 if (new->flags & IRQF_PERCPU)
 416                         desc->status |= IRQ_PER_CPU;
 417 #endif
 418
 419                 desc->status &= ~(IRQ_AUTODETECT | IRQ_WAITING |
 420                                   IRQ_INPROGRESS | IRQ_SPURIOUS_DISABLED);
 421
 422                 if (!(desc->status & IRQ_NOAUTOEN)) {
 423                         desc->depth = 0;
 424                         desc->status &= ~IRQ_DISABLED;
 425                         if (desc->chip->startup)
 426                                 desc->chip->startup(irq);
 427                         else
 428                                 desc->chip->enable(irq);
 429                 } else
 430                         /* Undo nested disables: */
 431                         desc->depth = 1;
 432
 433                 /* Set default affinity mask once everything is setup */
 434                 irq_select_affinity(irq);
 435         }
 436
 437         *p = new;
 438
 439         /* Exclude IRQ from balancing */
 440         if (new->flags & IRQF_NOBALANCING)
 441                 desc->status |= IRQ_NO_BALANCING;
 442
 443         /* Reset broken irq detection when installing new handler */
 444         desc->irq_count = 0;
 445         desc->irqs_unhandled = 0;
 446
 447         /*
 448          * Check whether we disabled the irq via the spurious handler
 449          * before. Reenable it and give it another chance.
 450          */
 451         if (shared && (desc->status & IRQ_SPURIOUS_DISABLED)) {
 452                 desc->status &= ~IRQ_SPURIOUS_DISABLED;
 453                 __enable_irq(desc, irq);
 454         }
 455
 456         spin_unlock_irqrestore(&desc->lock, flags);
 457
 458         new->irq = irq;
 459         register_irq_proc(irq);
 460         new->dir = NULL;
 461         register_handler_proc(irq, new);
 462
 463         return 0;
 464
 465 mismatch:
 466 #ifdef CONFIG_DEBUG_SHIRQ
 467         if (!(new->flags & IRQF_PROBE_SHARED)) {
 468                 printk(KERN_ERR "IRQ handler type mismatch for IRQ %d\n", irq);
 469                 if (old_name)
 470                         printk(KERN_ERR "current handler: %s\n", old_name);
 471                 dump_stack();
 472         }
 473 #endif
 474         spin_unlock_irqrestore(&desc->lock, flags);
 475         return -EBUSY;
 476 }
 477
 478 /**
 479  *      free_irq - free an interrupt
 480  *      @irq: Interrupt line to free
 481  *      @dev_id: Device identity to free
 482  *
 483  *      Remove an interrupt handler. The handler is removed and if the
 484  *      interrupt line is no longer in use by any driver it is disabled.
 485  *      On a shared IRQ the caller must ensure the interrupt is disabled
 486  *      on the card it drives before calling this function. The function
 487  *      does not return until any executing interrupts for this IRQ
 488  *      have completed.
 489  *
 490  *      This function must not be called from interrupt context.
 491  */
 492 void free_irq(unsigned int irq, void *dev_id)
 493 {
 494         struct irq_desc *desc;
 495         struct irqaction **p;
 496         unsigned long flags;
 497
 498         WARN_ON(in_interrupt());
 499         if (irq >= NR_IRQS)
 500                 return;
 501
 502         desc = irq_desc + irq;
 503         spin_lock_irqsave(&desc->lock, flags);
 504         p = &desc->action;
 505         for (;;) {
 506                 struct irqaction *action = *p;
 507
 508                 if (action) {
 509                         struct irqaction **pp = p;
 510
 511                         p = &action->next;
 512                         if (action->dev_id != dev_id)
 513                                 continue;
 514
 515                         /* Found it - now remove it from the list of entries */
 516                         *pp = action->next;
 517
 518                         /* Currently used only by UML, might disappear one day.*/
 519 #ifdef CONFIG_IRQ_RELEASE_METHOD
 520                         if (desc->chip->release)
 521                                 desc->chip->release(irq, dev_id);
 522 #endif
 523
 524                         if (!desc->action) {
 525                                 desc->status |= IRQ_DISABLED;
 526                                 if (desc->chip->shutdown)
 527                                         desc->chip->shutdown(irq);
 528                                 else
 529                                         desc->chip->disable(irq);
 530                         }
 531                         spin_unlock_irqrestore(&desc->lock, flags);
 532                         unregister_handler_proc(irq, action);
 533
 534                         /* Make sure it's not being used on another CPU */
 535                         synchronize_irq(irq);
 536 #ifdef CONFIG_DEBUG_SHIRQ
 537                         /*
 538                          * It's a shared IRQ -- the driver ought to be
 539                          * prepared for it to happen even now it's
 540                          * being freed, so let's make sure....  We do
 541                          * this after actually deregistering it, to
 542                          * make sure that a 'real' IRQ doesn't run in
 543                          * parallel with our fake
 544                          */
 545                         if (action->flags & IRQF_SHARED) {
 546                                 local_irq_save(flags);
 547                                 action->handler(irq, dev_id);
 548                                 local_irq_restore(flags);
 549                         }
 550 #endif
 551                         kfree(action);
 552                         return;
 553                 }
 554                 printk(KERN_ERR "Trying to free already-free IRQ %d\n", irq);
 555 #ifdef CONFIG_DEBUG_SHIRQ
 556                 dump_stack();
 557 #endif
 558                 spin_unlock_irqrestore(&desc->lock, flags);
 559                 return;
 560         }
 561 }
 562 EXPORT_SYMBOL(free_irq);
 563
 564 /**
 565  *      request_irq - allocate an interrupt line
 566  *      @irq: Interrupt line to allocate
 567  *      @handler: Function to be called when the IRQ occurs
 568  *      @irqflags: Interrupt type flags
 569  *      @devname: An ascii name for the claiming device
 570  *      @dev_id: A cookie passed back to the handler function
 571  *
 572  *      This call allocates interrupt resources and enables the
 573  *      interrupt line and IRQ handling. From the point this
 574  *      call is made your handler function may be invoked. Since
 575  *      your handler function must clear any interrupt the board
 576  *      raises, you must take care both to initialise your hardware
 577  *      and to set up the interrupt handler in the right order.
 578  *
 579  *      Dev_id must be globally unique. Normally the address of the
 580  *      device data structure is used as the cookie. Since the handler
 581  *      receives this value it makes sense to use it.
 582  *
 583  *      If your interrupt is shared you must pass a non NULL dev_id
 584  *      as this is required when freeing the interrupt.
 585  *
 586  *      Flags:
 587  *
 588  *      IRQF_SHARED             Interrupt is shared
 589  *      IRQF_DISABLED   Disable local interrupts while processing
 590  *      IRQF_SAMPLE_RANDOM      The interrupt can be used for entropy
 591  *
 592  */
 593 int request_irq(unsigned int irq, irq_handler_t handler,
 594                 unsigned long irqflags, const char *devname, void *dev_id)
 595 {
 596         struct irqaction *action;
 597         int retval;
 598
 599 #ifdef CONFIG_LOCKDEP
 600         /*
 601          * Lockdep wants atomic interrupt handlers:
 602          */
 603         irqflags |= IRQF_DISABLED;
 604 #endif
 605         /*
 606          * Sanity-check: shared interrupts must pass in a real dev-ID,
 607          * otherwise we'll have trouble later trying to figure out
 608          * which interrupt is which (messes up the interrupt freeing
 609          * logic etc).
 610          */
 611         if ((irqflags & IRQF_SHARED) && !dev_id)
 612                 return -EINVAL;
 613         if (irq >= NR_IRQS)
 614                 return -EINVAL;
 615         if (irq_desc[irq].status & IRQ_NOREQUEST)
 616                 return -EINVAL;
 617         if (!handler)
 618                 return -EINVAL;
 619
 620         action = kmalloc(sizeof(struct irqaction), GFP_ATOMIC);
 621         if (!action)
 622                 return -ENOMEM;
 623
 624         action->handler = handler;
 625         action->flags = irqflags;
 626         cpus_clear(action->mask);
 627         action->name = devname;
 628         action->next = NULL;
 629         action->dev_id = dev_id;
 630
 631 #ifdef CONFIG_DEBUG_SHIRQ
 632         if (irqflags & IRQF_SHARED) {
 633                 /*
 634                  * It's a shared IRQ -- the driver ought to be prepared for it
 635                  * to happen immediately, so let's make sure....
 636                  * We do this before actually registering it, to make sure that
 637                  * a 'real' IRQ doesn't run in parallel with our fake
 638                  */
 639                 unsigned long flags;
 640
 641                 local_irq_save(flags);
 642                 handler(irq, dev_id);
 643                 local_irq_restore(flags);
 644         }
 645 #endif
 646
 647         retval = setup_irq(irq, action);
 648         if (retval)
 649                 kfree(action);
 650
 651         return retval;
 652 }
 653 EXPORT_SYMBOL(request_irq);