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                 WARN(1, KERN_WARNING "Unbalanced enable for IRQ %d\n", irq);
 188                 break;
 189         case 1: {
 190                 unsigned int status = desc->status & ~IRQ_DISABLED;
 191
 192                 /* Prevent probing on this irq: */
 193                 desc->status = status | IRQ_NOPROBE;
 194                 check_irq_resend(desc, irq);
 195                 /* fall-through */
 196         }
 197         default:
 198                 desc->depth--;
 199         }
 200 }
 201
 202 /**
 203  *      enable_irq - enable handling of an irq
 204  *      @irq: Interrupt to enable
 205  *
 206  *      Undoes the effect of one call to disable_irq().  If this
 207  *      matches the last disable, processing of interrupts on this
 208  *      IRQ line is re-enabled.
 209  *
 210  *      This function may be called from IRQ context.
 211  */
 212 void enable_irq(unsigned int irq)
 213 {
 214         struct irq_desc *desc = irq_desc + irq;
 215         unsigned long flags;
 216
 217         if (irq >= NR_IRQS)
 218                 return;
 219
 220         spin_lock_irqsave(&desc->lock, flags);
 221         __enable_irq(desc, irq);
 222         spin_unlock_irqrestore(&desc->lock, flags);
 223 }
 224 EXPORT_SYMBOL(enable_irq);
 225
 226 int set_irq_wake_real(unsigned int irq, unsigned int on)
 227 {
 228         struct irq_desc *desc = irq_desc + irq;
 229         int ret = -ENXIO;
 230
 231         if (desc->chip->set_wake)
 232                 ret = desc->chip->set_wake(irq, on);
 233
 234         return ret;
 235 }
 236
 237 /**
 238  *      set_irq_wake - control irq power management wakeup
 239  *      @irq:   interrupt to control
 240  *      @on:    enable/disable power management wakeup
 241  *
 242  *      Enable/disable power management wakeup mode, which is
 243  *      disabled by default.  Enables and disables must match,
 244  *      just as they match for non-wakeup mode support.
 245  *
 246  *      Wakeup mode lets this IRQ wake the system from sleep
 247  *      states like "suspend to RAM".
 248  */
 249 int set_irq_wake(unsigned int irq, unsigned int on)
 250 {
 251         struct irq_desc *desc = irq_desc + irq;
 252         unsigned long flags;
 253         int ret = 0;
 254
 255         /* wakeup-capable irqs can be shared between drivers that
 256          * don't need to have the same sleep mode behaviors.
 257          */
 258         spin_lock_irqsave(&desc->lock, flags);
 259         if (on) {
 260                 if (desc->wake_depth++ == 0) {
 261                         ret = set_irq_wake_real(irq, on);
 262                         if (ret)
 263                                 desc->wake_depth = 0;
 264                         else
 265                                 desc->status |= IRQ_WAKEUP;
 266                 }
 267         } else {
 268                 if (desc->wake_depth == 0) {
 269                         WARN(1, "Unbalanced IRQ %d wake disable\n", irq);
 270                 } else if (--desc->wake_depth == 0) {
 271                         ret = set_irq_wake_real(irq, on);
 272                         if (ret)
 273                                 desc->wake_depth = 1;
 274                         else
 275                                 desc->status &= ~IRQ_WAKEUP;
 276                 }
 277         }
 278
 279         spin_unlock_irqrestore(&desc->lock, flags);
 280         return ret;
 281 }
 282 EXPORT_SYMBOL(set_irq_wake);
 283
 284 /*
 285  * Internal function that tells the architecture code whether a
 286  * particular irq has been exclusively allocated or is available
 287  * for driver use.
 288  */
 289 int can_request_irq(unsigned int irq, unsigned long irqflags)
 290 {
 291         struct irqaction *action;
 292
 293         if (irq >= NR_IRQS || irq_desc[irq].status & IRQ_NOREQUEST)
 294                 return 0;
 295
 296         action = irq_desc[irq].action;
 297         if (action)
 298                 if (irqflags & action->flags & IRQF_SHARED)
 299                         action = NULL;
 300
 301         return !action;
 302 }
 303
 304 void compat_irq_chip_set_default_handler(struct irq_desc *desc)
 305 {
 306         /*
 307          * If the architecture still has not overriden
 308          * the flow handler then zap the default. This
 309          * should catch incorrect flow-type setting.
 310          */
 311         if (desc->handle_irq == &handle_bad_irq)
 312                 desc->handle_irq = NULL;
 313 }
 314
 315 static int __irq_set_trigger(struct irq_chip *chip, unsigned int irq,
 316                 unsigned long flags)
 317 {
 318         int ret;
 319
 320         if (!chip || !chip->set_type) {
 321                 /*
 322                  * IRQF_TRIGGER_* but the PIC does not support multiple
 323                  * flow-types?
 324                  */
 325                 pr_warning("No set_type function for IRQ %d (%s)\n", irq,
 326                                 chip ? (chip->name ? : "unknown") : "unknown");
 327                 return 0;
 328         }
 329
 330         ret = chip->set_type(irq, flags & IRQF_TRIGGER_MASK);
 331
 332         if (ret)
 333                 pr_err("setting flow type for irq %u failed (%pF)\n",
 334                                 irq, chip->set_type);
 335
 336         return ret;
 337 }
 338
 339 /*
 340  * Internal function to register an irqaction - typically used to
 341  * allocate special interrupts that are part of the architecture.
 342  */
 343 int setup_irq(unsigned int irq, struct irqaction *new)
 344 {
 345         struct irq_desc *desc = irq_desc + irq;
 346         struct irqaction *old, **p;
 347         const char *old_name = NULL;
 348         unsigned long flags;
 349         int shared = 0;
 350         int ret;
 351
 352         if (irq >= NR_IRQS)
 353                 return -EINVAL;
 354
 355         if (desc->chip == &no_irq_chip)
 356                 return -ENOSYS;
 357         /*
 358          * Some drivers like serial.c use request_irq() heavily,
 359          * so we have to be careful not to interfere with a
 360          * running system.
 361          */
 362         if (new->flags & IRQF_SAMPLE_RANDOM) {
 363                 /*
 364                  * This function might sleep, we want to call it first,
 365                  * outside of the atomic block.
 366                  * Yes, this might clear the entropy pool if the wrong
 367                  * driver is attempted to be loaded, without actually
 368                  * installing a new handler, but is this really a problem,
 369                  * only the sysadmin is able to do this.
 370                  */
 371                 rand_initialize_irq(irq);
 372         }
 373
 374         /*
 375          * The following block of code has to be executed atomically
 376          */
 377         spin_lock_irqsave(&desc->lock, flags);
 378         p = &desc->action;
 379         old = *p;
 380         if (old) {
 381                 /*
 382                  * Can't share interrupts unless both agree to and are
 383                  * the same type (level, edge, polarity). So both flag
 384                  * fields must have IRQF_SHARED set and the bits which
 385                  * set the trigger type must match.
 386                  */
 387                 if (!((old->flags & new->flags) & IRQF_SHARED) ||
 388                     ((old->flags ^ new->flags) & IRQF_TRIGGER_MASK)) {
 389                         old_name = old->name;
 390                         goto mismatch;
 391                 }
 392
 393 #if defined(CONFIG_IRQ_PER_CPU)
 394                 /* All handlers must agree on per-cpuness */
 395                 if ((old->flags & IRQF_PERCPU) !=
 396                     (new->flags & IRQF_PERCPU))
 397                         goto mismatch;
 398 #endif
 399
 400                 /* add new interrupt at end of irq queue */
 401                 do {
 402                         p = &old->next;
 403                         old = *p;
 404                 } while (old);
 405                 shared = 1;
 406         }
 407
 408         if (!shared) {
 409                 irq_chip_set_defaults(desc->chip);
 410
 411                 /* Setup the type (level, edge polarity) if configured: */
 412                 if (new->flags & IRQF_TRIGGER_MASK) {
 413                         ret = __irq_set_trigger(desc->chip, irq, new->flags);
 414
 415                         if (ret) {
 416                                 spin_unlock_irqrestore(&desc->lock, flags);
 417                                 return ret;
 418                         }
 419                 } else
 420                         compat_irq_chip_set_default_handler(desc);
 421 #if defined(CONFIG_IRQ_PER_CPU)
 422                 if (new->flags & IRQF_PERCPU)
 423                         desc->status |= IRQ_PER_CPU;
 424 #endif
 425
 426                 desc->status &= ~(IRQ_AUTODETECT | IRQ_WAITING |
 427                                   IRQ_INPROGRESS | IRQ_SPURIOUS_DISABLED);
 428
 429                 if (!(desc->status & IRQ_NOAUTOEN)) {
 430                         desc->depth = 0;
 431                         desc->status &= ~IRQ_DISABLED;
 432                         if (desc->chip->startup)
 433                                 desc->chip->startup(irq);
 434                         else
 435                                 desc->chip->enable(irq);
 436                 } else
 437                         /* Undo nested disables: */
 438                         desc->depth = 1;
 439
 440                 /* Set default affinity mask once everything is setup */
 441                 irq_select_affinity(irq);
 442         }
 443
 444         *p = new;
 445
 446         /* Exclude IRQ from balancing */
 447         if (new->flags & IRQF_NOBALANCING)
 448                 desc->status |= IRQ_NO_BALANCING;
 449
 450         /* Reset broken irq detection when installing new handler */
 451         desc->irq_count = 0;
 452         desc->irqs_unhandled = 0;
 453
 454         /*
 455          * Check whether we disabled the irq via the spurious handler
 456          * before. Reenable it and give it another chance.
 457          */
 458         if (shared && (desc->status & IRQ_SPURIOUS_DISABLED)) {
 459                 desc->status &= ~IRQ_SPURIOUS_DISABLED;
 460                 __enable_irq(desc, irq);
 461         }
 462
 463         spin_unlock_irqrestore(&desc->lock, flags);
 464
 465         new->irq = irq;
 466         register_irq_proc(irq);
 467         new->dir = NULL;
 468         register_handler_proc(irq, new);
 469
 470         return 0;
 471
 472 mismatch:
 473 #ifdef CONFIG_DEBUG_SHIRQ
 474         if (!(new->flags & IRQF_PROBE_SHARED)) {
 475                 printk(KERN_ERR "IRQ handler type mismatch for IRQ %d\n", irq);
 476                 if (old_name)
 477                         printk(KERN_ERR "current handler: %s\n", old_name);
 478                 dump_stack();
 479         }
 480 #endif
 481         spin_unlock_irqrestore(&desc->lock, flags);
 482         return -EBUSY;
 483 }
 484
 485 /**
 486  *      free_irq - free an interrupt
 487  *      @irq: Interrupt line to free
 488  *      @dev_id: Device identity to free
 489  *
 490  *      Remove an interrupt handler. The handler is removed and if the
 491  *      interrupt line is no longer in use by any driver it is disabled.
 492  *      On a shared IRQ the caller must ensure the interrupt is disabled
 493  *      on the card it drives before calling this function. The function
 494  *      does not return until any executing interrupts for this IRQ
 495  *      have completed.
 496  *
 497  *      This function must not be called from interrupt context.
 498  */
 499 void free_irq(unsigned int irq, void *dev_id)
 500 {
 501         struct irq_desc *desc;
 502         struct irqaction **p;
 503         unsigned long flags;
 504
 505         WARN_ON(in_interrupt());
 506         if (irq >= NR_IRQS)
 507                 return;
 508
 509         desc = irq_desc + irq;
 510         spin_lock_irqsave(&desc->lock, flags);
 511         p = &desc->action;
 512         for (;;) {
 513                 struct irqaction *action = *p;
 514
 515                 if (action) {
 516                         struct irqaction **pp = p;
 517
 518                         p = &action->next;
 519                         if (action->dev_id != dev_id)
 520                                 continue;
 521
 522                         /* Found it - now remove it from the list of entries */
 523                         *pp = action->next;
 524
 525                         /* Currently used only by UML, might disappear one day.*/
 526 #ifdef CONFIG_IRQ_RELEASE_METHOD
 527                         if (desc->chip->release)
 528                                 desc->chip->release(irq, dev_id);
 529 #endif
 530
 531                         if (!desc->action) {
 532                                 desc->status |= IRQ_DISABLED;
 533                                 if (desc->chip->shutdown)
 534                                         desc->chip->shutdown(irq);
 535                                 else
 536                                         desc->chip->disable(irq);
 537                         }
 538                         spin_unlock_irqrestore(&desc->lock, flags);
 539                         unregister_handler_proc(irq, action);
 540
 541                         /* Make sure it's not being used on another CPU */
 542                         synchronize_irq(irq);
 543 #ifdef CONFIG_DEBUG_SHIRQ
 544                         /*
 545                          * It's a shared IRQ -- the driver ought to be
 546                          * prepared for it to happen even now it's
 547                          * being freed, so let's make sure....  We do
 548                          * this after actually deregistering it, to
 549                          * make sure that a 'real' IRQ doesn't run in
 550                          * parallel with our fake
 551                          */
 552                         if (action->flags & IRQF_SHARED) {
 553                                 local_irq_save(flags);
 554                                 action->handler(irq, dev_id);
 555                                 local_irq_restore(flags);
 556                         }
 557 #endif
 558                         kfree(action);
 559                         return;
 560                 }
 561                 printk(KERN_ERR "Trying to free already-free IRQ %d\n", irq);
 562 #ifdef CONFIG_DEBUG_SHIRQ
 563                 dump_stack();
 564 #endif
 565                 spin_unlock_irqrestore(&desc->lock, flags);
 566                 return;
 567         }
 568 }
 569 EXPORT_SYMBOL(free_irq);
 570
 571 /**
 572  *      request_irq - allocate an interrupt line
 573  *      @irq: Interrupt line to allocate
 574  *      @handler: Function to be called when the IRQ occurs
 575  *      @irqflags: Interrupt type flags
 576  *      @devname: An ascii name for the claiming device
 577  *      @dev_id: A cookie passed back to the handler function
 578  *
 579  *      This call allocates interrupt resources and enables the
 580  *      interrupt line and IRQ handling. From the point this
 581  *      call is made your handler function may be invoked. Since
 582  *      your handler function must clear any interrupt the board
 583  *      raises, you must take care both to initialise your hardware
 584  *      and to set up the interrupt handler in the right order.
 585  *
 586  *      Dev_id must be globally unique. Normally the address of the
 587  *      device data structure is used as the cookie. Since the handler
 588  *      receives this value it makes sense to use it.
 589  *
 590  *      If your interrupt is shared you must pass a non NULL dev_id
 591  *      as this is required when freeing the interrupt.
 592  *
 593  *      Flags:
 594  *
 595  *      IRQF_SHARED             Interrupt is shared
 596  *      IRQF_DISABLED   Disable local interrupts while processing
 597  *      IRQF_SAMPLE_RANDOM      The interrupt can be used for entropy
 598  *
 599  */
 600 int request_irq(unsigned int irq, irq_handler_t handler,
 601                 unsigned long irqflags, const char *devname, void *dev_id)
 602 {
 603         struct irqaction *action;
 604         int retval;
 605
 606 #ifdef CONFIG_LOCKDEP
 607         /*
 608          * Lockdep wants atomic interrupt handlers:
 609          */
 610         irqflags |= IRQF_DISABLED;
 611 #endif
 612         /*
 613          * Sanity-check: shared interrupts must pass in a real dev-ID,
 614          * otherwise we'll have trouble later trying to figure out
 615          * which interrupt is which (messes up the interrupt freeing
 616          * logic etc).
 617          */
 618         if ((irqflags & IRQF_SHARED) && !dev_id)
 619                 return -EINVAL;
 620         if (irq >= NR_IRQS)
 621                 return -EINVAL;
 622         if (irq_desc[irq].status & IRQ_NOREQUEST)
 623                 return -EINVAL;
 624         if (!handler)
 625                 return -EINVAL;
 626
 627         action = kmalloc(sizeof(struct irqaction), GFP_ATOMIC);
 628         if (!action)
 629                 return -ENOMEM;
 630
 631         action->handler = handler;
 632         action->flags = irqflags;
 633         cpus_clear(action->mask);
 634         action->name = devname;
 635         action->next = NULL;
 636         action->dev_id = dev_id;
 637
 638 #ifdef CONFIG_DEBUG_SHIRQ
 639         if (irqflags & IRQF_SHARED) {
 640                 /*
 641                  * It's a shared IRQ -- the driver ought to be prepared for it
 642                  * to happen immediately, so let's make sure....
 643                  * We do this before actually registering it, to make sure that
 644                  * a 'real' IRQ doesn't run in parallel with our fake
 645                  */
 646                 unsigned long flags;
 647
 648                 local_irq_save(flags);
 649                 handler(irq, dev_id);
 650                 local_irq_restore(flags);
 651         }
 652 #endif
 653
 654         retval = setup_irq(irq, action);
 655         if (retval)
 656                 kfree(action);
 657
 658         return retval;
 659 }
 660 EXPORT_SYMBOL(request_irq);