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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 /**
  21  *      synchronize_irq - wait for pending IRQ handlers (on other CPUs)
  22  *      @irq: interrupt number to wait for
  23  *
  24  *      This function waits for any pending IRQ handlers for this interrupt
  25  *      to complete before returning. If you use this function while
  26  *      holding a resource the IRQ handler may need you will deadlock.
  27  *
  28  *      This function may be called - with care - from IRQ context.
  29  */
  30 void synchronize_irq(unsigned int irq)
  31 {
  32         struct irq_desc *desc = irq_desc + irq;
  33         unsigned int status;
  34
  35         if (irq >= NR_IRQS)
  36                 return;
  37
  38         do {
  39                 unsigned long flags;
  40
  41                 /*
  42                  * Wait until we're out of the critical section.  This might
  43                  * give the wrong answer due to the lack of memory barriers.
  44                  */
  45                 while (desc->status & IRQ_INPROGRESS)
  46                         cpu_relax();
  47
  48                 /* Ok, that indicated we're done: double-check carefully. */
  49                 spin_lock_irqsave(&desc->lock, flags);
  50                 status = desc->status;
  51                 spin_unlock_irqrestore(&desc->lock, flags);
  52
  53                 /* Oops, that failed? */
  54         } while (status & IRQ_INPROGRESS);
  55 }
  56 EXPORT_SYMBOL(synchronize_irq);
  57
  58 /**
  59  *      irq_can_set_affinity - Check if the affinity of a given irq can be set
  60  *      @irq:           Interrupt to check
  61  *
  62  */
  63 int irq_can_set_affinity(unsigned int irq)
  64 {
  65         struct irq_desc *desc = irq_desc + irq;
  66
  67         if (CHECK_IRQ_PER_CPU(desc->status) || !desc->chip ||
  68             !desc->chip->set_affinity)
  69                 return 0;
  70
  71         return 1;
  72 }
  73
  74 /**
  75  *      irq_set_affinity - Set the irq affinity of a given irq
  76  *      @irq:           Interrupt to set affinity
  77  *      @cpumask:       cpumask
  78  *
  79  */
  80 int irq_set_affinity(unsigned int irq, cpumask_t cpumask)
  81 {
  82         struct irq_desc *desc = irq_desc + irq;
  83
  84         if (!desc->chip->set_affinity)
  85                 return -EINVAL;
  86
  87         set_balance_irq_affinity(irq, cpumask);
  88
  89 #ifdef CONFIG_GENERIC_PENDING_IRQ
  90         set_pending_irq(irq, cpumask);
  91 #else
  92         desc->affinity = cpumask;
  93         desc->chip->set_affinity(irq, cpumask);
  94 #endif
  95         return 0;
  96 }
  97
  98 #endif
  99
 100 /**
 101  *      disable_irq_nosync - disable an irq without waiting
 102  *      @irq: Interrupt to disable
 103  *
 104  *      Disable the selected interrupt line.  Disables and Enables are
 105  *      nested.
 106  *      Unlike disable_irq(), this function does not ensure existing
 107  *      instances of the IRQ handler have completed before returning.
 108  *
 109  *      This function may be called from IRQ context.
 110  */
 111 void disable_irq_nosync(unsigned int irq)
 112 {
 113         struct irq_desc *desc = irq_desc + irq;
 114         unsigned long flags;
 115
 116         if (irq >= NR_IRQS)
 117                 return;
 118
 119         spin_lock_irqsave(&desc->lock, flags);
 120         if (!desc->depth++) {
 121                 desc->status |= IRQ_DISABLED;
 122                 desc->chip->disable(irq);
 123         }
 124         spin_unlock_irqrestore(&desc->lock, flags);
 125 }
 126 EXPORT_SYMBOL(disable_irq_nosync);
 127
 128 /**
 129  *      disable_irq - disable an irq and wait for completion
 130  *      @irq: Interrupt to disable
 131  *
 132  *      Disable the selected interrupt line.  Enables and Disables are
 133  *      nested.
 134  *      This function waits for any pending IRQ handlers for this interrupt
 135  *      to complete before returning. If you use this function while
 136  *      holding a resource the IRQ handler may need you will deadlock.
 137  *
 138  *      This function may be called - with care - from IRQ context.
 139  */
 140 void disable_irq(unsigned int irq)
 141 {
 142         struct irq_desc *desc = irq_desc + irq;
 143
 144         if (irq >= NR_IRQS)
 145                 return;
 146
 147         disable_irq_nosync(irq);
 148         if (desc->action)
 149                 synchronize_irq(irq);
 150 }
 151 EXPORT_SYMBOL(disable_irq);
 152
 153 static void __enable_irq(struct irq_desc *desc, unsigned int irq)
 154 {
 155         switch (desc->depth) {
 156         case 0:
 157                 printk(KERN_WARNING "Unbalanced enable for IRQ %d\n", irq);
 158                 WARN_ON(1);
 159                 break;
 160         case 1: {
 161                 unsigned int status = desc->status & ~IRQ_DISABLED;
 162
 163                 /* Prevent probing on this irq: */
 164                 desc->status = status | IRQ_NOPROBE;
 165                 check_irq_resend(desc, irq);
 166                 /* fall-through */
 167         }
 168         default:
 169                 desc->depth--;
 170         }
 171 }
 172
 173 /**
 174  *      enable_irq - enable handling of an irq
 175  *      @irq: Interrupt to enable
 176  *
 177  *      Undoes the effect of one call to disable_irq().  If this
 178  *      matches the last disable, processing of interrupts on this
 179  *      IRQ line is re-enabled.
 180  *
 181  *      This function may be called from IRQ context.
 182  */
 183 void enable_irq(unsigned int irq)
 184 {
 185         struct irq_desc *desc = irq_desc + irq;
 186         unsigned long flags;
 187
 188         if (irq >= NR_IRQS)
 189                 return;
 190
 191         spin_lock_irqsave(&desc->lock, flags);
 192         __enable_irq(desc, irq);
 193         spin_unlock_irqrestore(&desc->lock, flags);
 194 }
 195 EXPORT_SYMBOL(enable_irq);
 196
 197 /**
 198  *      set_irq_wake - control irq power management wakeup
 199  *      @irq:   interrupt to control
 200  *      @on:    enable/disable power management wakeup
 201  *
 202  *      Enable/disable power management wakeup mode, which is
 203  *      disabled by default.  Enables and disables must match,
 204  *      just as they match for non-wakeup mode support.
 205  *
 206  *      Wakeup mode lets this IRQ wake the system from sleep
 207  *      states like "suspend to RAM".
 208  */
 209 int set_irq_wake(unsigned int irq, unsigned int on)
 210 {
 211         struct irq_desc *desc = irq_desc + irq;
 212         unsigned long flags;
 213         int ret = -ENXIO;
 214         int (*set_wake)(unsigned, unsigned) = desc->chip->set_wake;
 215
 216         /* wakeup-capable irqs can be shared between drivers that
 217          * don't need to have the same sleep mode behaviors.
 218          */
 219         spin_lock_irqsave(&desc->lock, flags);
 220         if (on) {
 221                 if (desc->wake_depth++ == 0)
 222                         desc->status |= IRQ_WAKEUP;
 223                 else
 224                         set_wake = NULL;
 225         } else {
 226                 if (desc->wake_depth == 0) {
 227                         printk(KERN_WARNING "Unbalanced IRQ %d "
 228                                         "wake disable\n", irq);
 229                         WARN_ON(1);
 230                 } else if (--desc->wake_depth == 0)
 231                         desc->status &= ~IRQ_WAKEUP;
 232                 else
 233                         set_wake = NULL;
 234         }
 235         if (set_wake)
 236                 ret = desc->chip->set_wake(irq, on);
 237         spin_unlock_irqrestore(&desc->lock, flags);
 238         return ret;
 239 }
 240 EXPORT_SYMBOL(set_irq_wake);
 241
 242 /*
 243  * Internal function that tells the architecture code whether a
 244  * particular irq has been exclusively allocated or is available
 245  * for driver use.
 246  */
 247 int can_request_irq(unsigned int irq, unsigned long irqflags)
 248 {
 249         struct irqaction *action;
 250
 251         if (irq >= NR_IRQS || irq_desc[irq].status & IRQ_NOREQUEST)
 252                 return 0;
 253
 254         action = irq_desc[irq].action;
 255         if (action)
 256                 if (irqflags & action->flags & IRQF_SHARED)
 257                         action = NULL;
 258
 259         return !action;
 260 }
 261
 262 void compat_irq_chip_set_default_handler(struct irq_desc *desc)
 263 {
 264         /*
 265          * If the architecture still has not overriden
 266          * the flow handler then zap the default. This
 267          * should catch incorrect flow-type setting.
 268          */
 269         if (desc->handle_irq == &handle_bad_irq)
 270                 desc->handle_irq = NULL;
 271 }
 272
 273 /*
 274  * Internal function to register an irqaction - typically used to
 275  * allocate special interrupts that are part of the architecture.
 276  */
 277 int setup_irq(unsigned int irq, struct irqaction *new)
 278 {
 279         struct irq_desc *desc = irq_desc + irq;
 280         struct irqaction *old, **p;
 281         const char *old_name = NULL;
 282         unsigned long flags;
 283         int shared = 0;
 284
 285         if (irq >= NR_IRQS)
 286                 return -EINVAL;
 287
 288         if (desc->chip == &no_irq_chip)
 289                 return -ENOSYS;
 290         /*
 291          * Some drivers like serial.c use request_irq() heavily,
 292          * so we have to be careful not to interfere with a
 293          * running system.
 294          */
 295         if (new->flags & IRQF_SAMPLE_RANDOM) {
 296                 /*
 297                  * This function might sleep, we want to call it first,
 298                  * outside of the atomic block.
 299                  * Yes, this might clear the entropy pool if the wrong
 300                  * driver is attempted to be loaded, without actually
 301                  * installing a new handler, but is this really a problem,
 302                  * only the sysadmin is able to do this.
 303                  */
 304                 rand_initialize_irq(irq);
 305         }
 306
 307         /*
 308          * The following block of code has to be executed atomically
 309          */
 310         spin_lock_irqsave(&desc->lock, flags);
 311         p = &desc->action;
 312         old = *p;
 313         if (old) {
 314                 /*
 315                  * Can't share interrupts unless both agree to and are
 316                  * the same type (level, edge, polarity). So both flag
 317                  * fields must have IRQF_SHARED set and the bits which
 318                  * set the trigger type must match.
 319                  */
 320                 if (!((old->flags & new->flags) & IRQF_SHARED) ||
 321                     ((old->flags ^ new->flags) & IRQF_TRIGGER_MASK)) {
 322                         old_name = old->name;
 323                         goto mismatch;
 324                 }
 325
 326 #if defined(CONFIG_IRQ_PER_CPU)
 327                 /* All handlers must agree on per-cpuness */
 328                 if ((old->flags & IRQF_PERCPU) !=
 329                     (new->flags & IRQF_PERCPU))
 330                         goto mismatch;
 331 #endif
 332
 333                 /* add new interrupt at end of irq queue */
 334                 do {
 335                         p = &old->next;
 336                         old = *p;
 337                 } while (old);
 338                 shared = 1;
 339         }
 340
 341         *p = new;
 342
 343         /* Exclude IRQ from balancing */
 344         if (new->flags & IRQF_NOBALANCING)
 345                 desc->status |= IRQ_NO_BALANCING;
 346
 347         if (!shared) {
 348                 irq_chip_set_defaults(desc->chip);
 349
 350 #if defined(CONFIG_IRQ_PER_CPU)
 351                 if (new->flags & IRQF_PERCPU)
 352                         desc->status |= IRQ_PER_CPU;
 353 #endif
 354
 355                 /* Setup the type (level, edge polarity) if configured: */
 356                 if (new->flags & IRQF_TRIGGER_MASK) {
 357                         if (desc->chip && desc->chip->set_type)
 358                                 desc->chip->set_type(irq,
 359                                                 new->flags & IRQF_TRIGGER_MASK);
 360                         else
 361                                 /*
 362                                  * IRQF_TRIGGER_* but the PIC does not support
 363                                  * multiple flow-types?
 364                                  */
 365                                 printk(KERN_WARNING "No IRQF_TRIGGER set_type "
 366                                        "function for IRQ %d (%s)\n", irq,
 367                                        desc->chip ? desc->chip->name :
 368                                        "unknown");
 369                 } else
 370                         compat_irq_chip_set_default_handler(desc);
 371
 372                 desc->status &= ~(IRQ_AUTODETECT | IRQ_WAITING |
 373                                   IRQ_INPROGRESS | IRQ_SPURIOUS_DISABLED);
 374
 375                 if (!(desc->status & IRQ_NOAUTOEN)) {
 376                         desc->depth = 0;
 377                         desc->status &= ~IRQ_DISABLED;
 378                         if (desc->chip->startup)
 379                                 desc->chip->startup(irq);
 380                         else
 381                                 desc->chip->enable(irq);
 382                 } else
 383                         /* Undo nested disables: */
 384                         desc->depth = 1;
 385         }
 386         /* Reset broken irq detection when installing new handler */
 387         desc->irq_count = 0;
 388         desc->irqs_unhandled = 0;
 389
 390         /*
 391          * Check whether we disabled the irq via the spurious handler
 392          * before. Reenable it and give it another chance.
 393          */
 394         if (shared && (desc->status & IRQ_SPURIOUS_DISABLED)) {
 395                 desc->status &= ~IRQ_SPURIOUS_DISABLED;
 396                 __enable_irq(desc, irq);
 397         }
 398
 399         spin_unlock_irqrestore(&desc->lock, flags);
 400
 401         new->irq = irq;
 402         register_irq_proc(irq);
 403         new->dir = NULL;
 404         register_handler_proc(irq, new);
 405
 406         return 0;
 407
 408 mismatch:
 409 #ifdef CONFIG_DEBUG_SHIRQ
 410         if (!(new->flags & IRQF_PROBE_SHARED)) {
 411                 printk(KERN_ERR "IRQ handler type mismatch for IRQ %d\n", irq);
 412                 if (old_name)
 413                         printk(KERN_ERR "current handler: %s\n", old_name);
 414                 dump_stack();
 415         }
 416 #endif
 417         spin_unlock_irqrestore(&desc->lock, flags);
 418         return -EBUSY;
 419 }
 420
 421 /**
 422  *      free_irq - free an interrupt
 423  *      @irq: Interrupt line to free
 424  *      @dev_id: Device identity to free
 425  *
 426  *      Remove an interrupt handler. The handler is removed and if the
 427  *      interrupt line is no longer in use by any driver it is disabled.
 428  *      On a shared IRQ the caller must ensure the interrupt is disabled
 429  *      on the card it drives before calling this function. The function
 430  *      does not return until any executing interrupts for this IRQ
 431  *      have completed.
 432  *
 433  *      This function must not be called from interrupt context.
 434  */
 435 void free_irq(unsigned int irq, void *dev_id)
 436 {
 437         struct irq_desc *desc;
 438         struct irqaction **p;
 439         unsigned long flags;
 440
 441         WARN_ON(in_interrupt());
 442         if (irq >= NR_IRQS)
 443                 return;
 444
 445         desc = irq_desc + irq;
 446         spin_lock_irqsave(&desc->lock, flags);
 447         p = &desc->action;
 448         for (;;) {
 449                 struct irqaction *action = *p;
 450
 451                 if (action) {
 452                         struct irqaction **pp = p;
 453
 454                         p = &action->next;
 455                         if (action->dev_id != dev_id)
 456                                 continue;
 457
 458                         /* Found it - now remove it from the list of entries */
 459                         *pp = action->next;
 460
 461                         /* Currently used only by UML, might disappear one day.*/
 462 #ifdef CONFIG_IRQ_RELEASE_METHOD
 463                         if (desc->chip->release)
 464                                 desc->chip->release(irq, dev_id);
 465 #endif
 466
 467                         if (!desc->action) {
 468                                 desc->status |= IRQ_DISABLED;
 469                                 if (desc->chip->shutdown)
 470                                         desc->chip->shutdown(irq);
 471                                 else
 472                                         desc->chip->disable(irq);
 473                         }
 474                         spin_unlock_irqrestore(&desc->lock, flags);
 475                         unregister_handler_proc(irq, action);
 476
 477                         /* Make sure it's not being used on another CPU */
 478                         synchronize_irq(irq);
 479 #ifdef CONFIG_DEBUG_SHIRQ
 480                         /*
 481                          * It's a shared IRQ -- the driver ought to be
 482                          * prepared for it to happen even now it's
 483                          * being freed, so let's make sure....  We do
 484                          * this after actually deregistering it, to
 485                          * make sure that a 'real' IRQ doesn't run in
 486                          * parallel with our fake
 487                          */
 488                         if (action->flags & IRQF_SHARED) {
 489                                 local_irq_save(flags);
 490                                 action->handler(irq, dev_id);
 491                                 local_irq_restore(flags);
 492                         }
 493 #endif
 494                         kfree(action);
 495                         return;
 496                 }
 497                 printk(KERN_ERR "Trying to free already-free IRQ %d\n", irq);
 498 #ifdef CONFIG_DEBUG_SHIRQ
 499                 dump_stack();
 500 #endif
 501                 spin_unlock_irqrestore(&desc->lock, flags);
 502                 return;
 503         }
 504 }
 505 EXPORT_SYMBOL(free_irq);
 506
 507 /**
 508  *      request_irq - allocate an interrupt line
 509  *      @irq: Interrupt line to allocate
 510  *      @handler: Function to be called when the IRQ occurs
 511  *      @irqflags: Interrupt type flags
 512  *      @devname: An ascii name for the claiming device
 513  *      @dev_id: A cookie passed back to the handler function
 514  *
 515  *      This call allocates interrupt resources and enables the
 516  *      interrupt line and IRQ handling. From the point this
 517  *      call is made your handler function may be invoked. Since
 518  *      your handler function must clear any interrupt the board
 519  *      raises, you must take care both to initialise your hardware
 520  *      and to set up the interrupt handler in the right order.
 521  *
 522  *      Dev_id must be globally unique. Normally the address of the
 523  *      device data structure is used as the cookie. Since the handler
 524  *      receives this value it makes sense to use it.
 525  *
 526  *      If your interrupt is shared you must pass a non NULL dev_id
 527  *      as this is required when freeing the interrupt.
 528  *
 529  *      Flags:
 530  *
 531  *      IRQF_SHARED             Interrupt is shared
 532  *      IRQF_DISABLED   Disable local interrupts while processing
 533  *      IRQF_SAMPLE_RANDOM      The interrupt can be used for entropy
 534  *
 535  */
 536 int request_irq(unsigned int irq, irq_handler_t handler,
 537                 unsigned long irqflags, const char *devname, void *dev_id)
 538 {
 539         struct irqaction *action;
 540         int retval;
 541
 542 #ifdef CONFIG_LOCKDEP
 543         /*
 544          * Lockdep wants atomic interrupt handlers:
 545          */
 546         irqflags |= IRQF_DISABLED;
 547 #endif
 548         /*
 549          * Sanity-check: shared interrupts must pass in a real dev-ID,
 550          * otherwise we'll have trouble later trying to figure out
 551          * which interrupt is which (messes up the interrupt freeing
 552          * logic etc).
 553          */
 554         if ((irqflags & IRQF_SHARED) && !dev_id)
 555                 return -EINVAL;
 556         if (irq >= NR_IRQS)
 557                 return -EINVAL;
 558         if (irq_desc[irq].status & IRQ_NOREQUEST)
 559                 return -EINVAL;
 560         if (!handler)
 561                 return -EINVAL;
 562
 563         action = kmalloc(sizeof(struct irqaction), GFP_ATOMIC);
 564         if (!action)
 565                 return -ENOMEM;
 566
 567         action->handler = handler;
 568         action->flags = irqflags;
 569         cpus_clear(action->mask);
 570         action->name = devname;
 571         action->next = NULL;
 572         action->dev_id = dev_id;
 573
 574         select_smp_affinity(irq);
 575
 576 #ifdef CONFIG_DEBUG_SHIRQ
 577         if (irqflags & IRQF_SHARED) {
 578                 /*
 579                  * It's a shared IRQ -- the driver ought to be prepared for it
 580                  * to happen immediately, so let's make sure....
 581                  * We do this before actually registering it, to make sure that
 582                  * a 'real' IRQ doesn't run in parallel with our fake
 583                  */
 584                 unsigned long flags;
 585
 586                 local_irq_save(flags);
 587                 handler(irq, dev_id);
 588                 local_irq_restore(flags);
 589         }
 590 #endif
 591
 592         retval = setup_irq(irq, action);
 593         if (retval)
 594                 kfree(action);
 595
 596         return retval;
 597 }
 598 EXPORT_SYMBOL(request_irq);