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                         printk(KERN_WARNING "Unbalanced IRQ %d "
 271                                         "wake disable\n", irq);
 272                         WARN_ON(1);
 273                 } else if (--desc->wake_depth == 0) {
 274                         ret = set_irq_wake_real(irq, on);
 275                         if (ret)
 276                                 desc->wake_depth = 1;
 277                         else
 278                                 desc->status &= ~IRQ_WAKEUP;
 279                 }
 280         }
 281
 282         spin_unlock_irqrestore(&desc->lock, flags);
 283         return ret;
 284 }
 285 EXPORT_SYMBOL(set_irq_wake);
 286
 287 /*
 288  * Internal function that tells the architecture code whether a
 289  * particular irq has been exclusively allocated or is available
 290  * for driver use.
 291  */
 292 int can_request_irq(unsigned int irq, unsigned long irqflags)
 293 {
 294         struct irqaction *action;
 295
 296         if (irq >= NR_IRQS || irq_desc[irq].status & IRQ_NOREQUEST)
 297                 return 0;
 298
 299         action = irq_desc[irq].action;
 300         if (action)
 301                 if (irqflags & action->flags & IRQF_SHARED)
 302                         action = NULL;
 303
 304         return !action;
 305 }
 306
 307 void compat_irq_chip_set_default_handler(struct irq_desc *desc)
 308 {
 309         /*
 310          * If the architecture still has not overriden
 311          * the flow handler then zap the default. This
 312          * should catch incorrect flow-type setting.
 313          */
 314         if (desc->handle_irq == &handle_bad_irq)
 315                 desc->handle_irq = NULL;
 316 }
 317
 318 static int __irq_set_trigger(struct irq_chip *chip, unsigned int irq,
 319                 unsigned long flags)
 320 {
 321         int ret;
 322
 323         if (!chip || !chip->set_type) {
 324                 /*
 325                  * IRQF_TRIGGER_* but the PIC does not support multiple
 326                  * flow-types?
 327                  */
 328                 pr_warning("No set_type function for IRQ %d (%s)\n", irq,
 329                                 chip ? (chip->name ? : "unknown") : "unknown");
 330                 return 0;
 331         }
 332
 333         ret = chip->set_type(irq, flags & IRQF_TRIGGER_MASK);
 334
 335         if (ret)
 336                 pr_err("setting flow type for irq %u failed (%pF)\n",
 337                                 irq, chip->set_type);
 338
 339         return ret;
 340 }
 341
 342 /*
 343  * Internal function to register an irqaction - typically used to
 344  * allocate special interrupts that are part of the architecture.
 345  */
 346 int setup_irq(unsigned int irq, struct irqaction *new)
 347 {
 348         struct irq_desc *desc = irq_desc + irq;
 349         struct irqaction *old, **p;
 350         const char *old_name = NULL;
 351         unsigned long flags;
 352         int shared = 0;
 353         int ret;
 354
 355         if (irq >= NR_IRQS)
 356                 return -EINVAL;
 357
 358         if (desc->chip == &no_irq_chip)
 359                 return -ENOSYS;
 360         /*
 361          * Some drivers like serial.c use request_irq() heavily,
 362          * so we have to be careful not to interfere with a
 363          * running system.
 364          */
 365         if (new->flags & IRQF_SAMPLE_RANDOM) {
 366                 /*
 367                  * This function might sleep, we want to call it first,
 368                  * outside of the atomic block.
 369                  * Yes, this might clear the entropy pool if the wrong
 370                  * driver is attempted to be loaded, without actually
 371                  * installing a new handler, but is this really a problem,
 372                  * only the sysadmin is able to do this.
 373                  */
 374                 rand_initialize_irq(irq);
 375         }
 376
 377         /*
 378          * The following block of code has to be executed atomically
 379          */
 380         spin_lock_irqsave(&desc->lock, flags);
 381         p = &desc->action;
 382         old = *p;
 383         if (old) {
 384                 /*
 385                  * Can't share interrupts unless both agree to and are
 386                  * the same type (level, edge, polarity). So both flag
 387                  * fields must have IRQF_SHARED set and the bits which
 388                  * set the trigger type must match.
 389                  */
 390                 if (!((old->flags & new->flags) & IRQF_SHARED) ||
 391                     ((old->flags ^ new->flags) & IRQF_TRIGGER_MASK)) {
 392                         old_name = old->name;
 393                         goto mismatch;
 394                 }
 395
 396 #if defined(CONFIG_IRQ_PER_CPU)
 397                 /* All handlers must agree on per-cpuness */
 398                 if ((old->flags & IRQF_PERCPU) !=
 399                     (new->flags & IRQF_PERCPU))
 400                         goto mismatch;
 401 #endif
 402
 403                 /* add new interrupt at end of irq queue */
 404                 do {
 405                         p = &old->next;
 406                         old = *p;
 407                 } while (old);
 408                 shared = 1;
 409         }
 410
 411         if (!shared) {
 412                 irq_chip_set_defaults(desc->chip);
 413
 414                 /* Setup the type (level, edge polarity) if configured: */
 415                 if (new->flags & IRQF_TRIGGER_MASK) {
 416                         ret = __irq_set_trigger(desc->chip, irq, new->flags);
 417
 418                         if (ret) {
 419                                 spin_unlock_irqrestore(&desc->lock, flags);
 420                                 return ret;
 421                         }
 422                 } else
 423                         compat_irq_chip_set_default_handler(desc);
 424 #if defined(CONFIG_IRQ_PER_CPU)
 425                 if (new->flags & IRQF_PERCPU)
 426                         desc->status |= IRQ_PER_CPU;
 427 #endif
 428
 429                 desc->status &= ~(IRQ_AUTODETECT | IRQ_WAITING |
 430                                   IRQ_INPROGRESS | IRQ_SPURIOUS_DISABLED);
 431
 432                 if (!(desc->status & IRQ_NOAUTOEN)) {
 433                         desc->depth = 0;
 434                         desc->status &= ~IRQ_DISABLED;
 435                         if (desc->chip->startup)
 436                                 desc->chip->startup(irq);
 437                         else
 438                                 desc->chip->enable(irq);
 439                 } else
 440                         /* Undo nested disables: */
 441                         desc->depth = 1;
 442
 443                 /* Set default affinity mask once everything is setup */
 444                 irq_select_affinity(irq);
 445         }
 446
 447         *p = new;
 448
 449         /* Exclude IRQ from balancing */
 450         if (new->flags & IRQF_NOBALANCING)
 451                 desc->status |= IRQ_NO_BALANCING;
 452
 453         /* Reset broken irq detection when installing new handler */
 454         desc->irq_count = 0;
 455         desc->irqs_unhandled = 0;
 456
 457         /*
 458          * Check whether we disabled the irq via the spurious handler
 459          * before. Reenable it and give it another chance.
 460          */
 461         if (shared && (desc->status & IRQ_SPURIOUS_DISABLED)) {
 462                 desc->status &= ~IRQ_SPURIOUS_DISABLED;
 463                 __enable_irq(desc, irq);
 464         }
 465
 466         spin_unlock_irqrestore(&desc->lock, flags);
 467
 468         new->irq = irq;
 469         register_irq_proc(irq);
 470         new->dir = NULL;
 471         register_handler_proc(irq, new);
 472
 473         return 0;
 474
 475 mismatch:
 476 #ifdef CONFIG_DEBUG_SHIRQ
 477         if (!(new->flags & IRQF_PROBE_SHARED)) {
 478                 printk(KERN_ERR "IRQ handler type mismatch for IRQ %d\n", irq);
 479                 if (old_name)
 480                         printk(KERN_ERR "current handler: %s\n", old_name);
 481                 dump_stack();
 482         }
 483 #endif
 484         spin_unlock_irqrestore(&desc->lock, flags);
 485         return -EBUSY;
 486 }
 487
 488 /**
 489  *      free_irq - free an interrupt
 490  *      @irq: Interrupt line to free
 491  *      @dev_id: Device identity to free
 492  *
 493  *      Remove an interrupt handler. The handler is removed and if the
 494  *      interrupt line is no longer in use by any driver it is disabled.
 495  *      On a shared IRQ the caller must ensure the interrupt is disabled
 496  *      on the card it drives before calling this function. The function
 497  *      does not return until any executing interrupts for this IRQ
 498  *      have completed.
 499  *
 500  *      This function must not be called from interrupt context.
 501  */
 502 void free_irq(unsigned int irq, void *dev_id)
 503 {
 504         struct irq_desc *desc;
 505         struct irqaction **p;
 506         unsigned long flags;
 507
 508         WARN_ON(in_interrupt());
 509         if (irq >= NR_IRQS)
 510                 return;
 511
 512         desc = irq_desc + irq;
 513         spin_lock_irqsave(&desc->lock, flags);
 514         p = &desc->action;
 515         for (;;) {
 516                 struct irqaction *action = *p;
 517
 518                 if (action) {
 519                         struct irqaction **pp = p;
 520
 521                         p = &action->next;
 522                         if (action->dev_id != dev_id)
 523                                 continue;
 524
 525                         /* Found it - now remove it from the list of entries */
 526                         *pp = action->next;
 527
 528                         /* Currently used only by UML, might disappear one day.*/
 529 #ifdef CONFIG_IRQ_RELEASE_METHOD
 530                         if (desc->chip->release)
 531                                 desc->chip->release(irq, dev_id);
 532 #endif
 533
 534                         if (!desc->action) {
 535                                 desc->status |= IRQ_DISABLED;
 536                                 if (desc->chip->shutdown)
 537                                         desc->chip->shutdown(irq);
 538                                 else
 539                                         desc->chip->disable(irq);
 540                         }
 541                         spin_unlock_irqrestore(&desc->lock, flags);
 542                         unregister_handler_proc(irq, action);
 543
 544                         /* Make sure it's not being used on another CPU */
 545                         synchronize_irq(irq);
 546 #ifdef CONFIG_DEBUG_SHIRQ
 547                         /*
 548                          * It's a shared IRQ -- the driver ought to be
 549                          * prepared for it to happen even now it's
 550                          * being freed, so let's make sure....  We do
 551                          * this after actually deregistering it, to
 552                          * make sure that a 'real' IRQ doesn't run in
 553                          * parallel with our fake
 554                          */
 555                         if (action->flags & IRQF_SHARED) {
 556                                 local_irq_save(flags);
 557                                 action->handler(irq, dev_id);
 558                                 local_irq_restore(flags);
 559                         }
 560 #endif
 561                         kfree(action);
 562                         return;
 563                 }
 564                 printk(KERN_ERR "Trying to free already-free IRQ %d\n", irq);
 565 #ifdef CONFIG_DEBUG_SHIRQ
 566                 dump_stack();
 567 #endif
 568                 spin_unlock_irqrestore(&desc->lock, flags);
 569                 return;
 570         }
 571 }
 572 EXPORT_SYMBOL(free_irq);
 573
 574 /**
 575  *      request_irq - allocate an interrupt line
 576  *      @irq: Interrupt line to allocate
 577  *      @handler: Function to be called when the IRQ occurs
 578  *      @irqflags: Interrupt type flags
 579  *      @devname: An ascii name for the claiming device
 580  *      @dev_id: A cookie passed back to the handler function
 581  *
 582  *      This call allocates interrupt resources and enables the
 583  *      interrupt line and IRQ handling. From the point this
 584  *      call is made your handler function may be invoked. Since
 585  *      your handler function must clear any interrupt the board
 586  *      raises, you must take care both to initialise your hardware
 587  *      and to set up the interrupt handler in the right order.
 588  *
 589  *      Dev_id must be globally unique. Normally the address of the
 590  *      device data structure is used as the cookie. Since the handler
 591  *      receives this value it makes sense to use it.
 592  *
 593  *      If your interrupt is shared you must pass a non NULL dev_id
 594  *      as this is required when freeing the interrupt.
 595  *
 596  *      Flags:
 597  *
 598  *      IRQF_SHARED             Interrupt is shared
 599  *      IRQF_DISABLED   Disable local interrupts while processing
 600  *      IRQF_SAMPLE_RANDOM      The interrupt can be used for entropy
 601  *
 602  */
 603 int request_irq(unsigned int irq, irq_handler_t handler,
 604                 unsigned long irqflags, const char *devname, void *dev_id)
 605 {
 606         struct irqaction *action;
 607         int retval;
 608
 609 #ifdef CONFIG_LOCKDEP
 610         /*
 611          * Lockdep wants atomic interrupt handlers:
 612          */
 613         irqflags |= IRQF_DISABLED;
 614 #endif
 615         /*
 616          * Sanity-check: shared interrupts must pass in a real dev-ID,
 617          * otherwise we'll have trouble later trying to figure out
 618          * which interrupt is which (messes up the interrupt freeing
 619          * logic etc).
 620          */
 621         if ((irqflags & IRQF_SHARED) && !dev_id)
 622                 return -EINVAL;
 623         if (irq >= NR_IRQS)
 624                 return -EINVAL;
 625         if (irq_desc[irq].status & IRQ_NOREQUEST)
 626                 return -EINVAL;
 627         if (!handler)
 628                 return -EINVAL;
 629
 630         action = kmalloc(sizeof(struct irqaction), GFP_ATOMIC);
 631         if (!action)
 632                 return -ENOMEM;
 633
 634         action->handler = handler;
 635         action->flags = irqflags;
 636         cpus_clear(action->mask);
 637         action->name = devname;
 638         action->next = NULL;
 639         action->dev_id = dev_id;
 640
 641 #ifdef CONFIG_DEBUG_SHIRQ
 642         if (irqflags & IRQF_SHARED) {
 643                 /*
 644                  * It's a shared IRQ -- the driver ought to be prepared for it
 645                  * to happen immediately, so let's make sure....
 646                  * We do this before actually registering it, to make sure that
 647                  * a 'real' IRQ doesn't run in parallel with our fake
 648                  */
 649                 unsigned long flags;
 650
 651                 local_irq_save(flags);
 652                 handler(irq, dev_id);
 653                 local_irq_restore(flags);
 654         }
 655 #endif
 656
 657         retval = setup_irq(irq, action);
 658         if (retval)
 659                 kfree(action);
 660
 661         return retval;
 662 }
 663 EXPORT_SYMBOL(request_irq);