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