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