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