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