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