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