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