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/kthread.h>
  12 #include <linux/module.h>
  13 #include <linux/random.h>
  14 #include <linux/interrupt.h>
  15 #include <linux/slab.h>
  16 #include <linux/sched.h>
  17
  18 #include "internals.h"
  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_to_desc(irq);
  33         unsigned int status;
  34
  35         if (!desc)
  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                 raw_spin_lock_irqsave(&desc->lock, flags);
  50                 status = desc->status;
  51                 raw_spin_unlock_irqrestore(&desc->lock, flags);
  52
  53                 /* Oops, that failed? */
  54         } while (status & IRQ_INPROGRESS);
  55
  56         /*
  57          * We made sure that no hardirq handler is running. Now verify
  58          * that no threaded handlers are active.
  59          */
  60         wait_event(desc->wait_for_threads, !atomic_read(&desc->threads_active));
  61 }
  62 EXPORT_SYMBOL(synchronize_irq);
  63
  64 #ifdef CONFIG_SMP
  65 cpumask_var_t irq_default_affinity;
  66
  67 /**
  68  *      irq_can_set_affinity - Check if the affinity of a given irq can be set
  69  *      @irq:           Interrupt to check
  70  *
  71  */
  72 int irq_can_set_affinity(unsigned int irq)
  73 {
  74         struct irq_desc *desc = irq_to_desc(irq);
  75
  76         if (CHECK_IRQ_PER_CPU(desc->status) || !desc->irq_data.chip ||
  77             !desc->irq_data.chip->irq_set_affinity)
  78                 return 0;
  79
  80         return 1;
  81 }
  82
  83 /**
  84  *      irq_set_thread_affinity - Notify irq threads to adjust affinity
  85  *      @desc:          irq descriptor which has affitnity changed
  86  *
  87  *      We just set IRQTF_AFFINITY and delegate the affinity setting
  88  *      to the interrupt thread itself. We can not call
  89  *      set_cpus_allowed_ptr() here as we hold desc->lock and this
  90  *      code can be called from hard interrupt context.
  91  */
  92 void irq_set_thread_affinity(struct irq_desc *desc)
  93 {
  94         struct irqaction *action = desc->action;
  95
  96         while (action) {
  97                 if (action->thread)
  98                         set_bit(IRQTF_AFFINITY, &action->thread_flags);
  99                 action = action->next;
 100         }
 101 }
 102
 103 /**
 104  *      irq_set_affinity - Set the irq affinity of a given irq
 105  *      @irq:           Interrupt to set affinity
 106  *      @cpumask:       cpumask
 107  *
 108  */
 109 int irq_set_affinity(unsigned int irq, const struct cpumask *cpumask)
 110 {
 111         struct irq_desc *desc = irq_to_desc(irq);
 112         struct irq_chip *chip = desc->irq_data.chip;
 113         unsigned long flags;
 114
 115         if (!chip->irq_set_affinity)
 116                 return -EINVAL;
 117
 118         raw_spin_lock_irqsave(&desc->lock, flags);
 119
 120 #ifdef CONFIG_GENERIC_PENDING_IRQ
 121         if (desc->status & IRQ_MOVE_PCNTXT) {
 122                 if (!chip->irq_set_affinity(&desc->irq_data, cpumask, false)) {
 123                         cpumask_copy(desc->irq_data.affinity, cpumask);
 124                         irq_set_thread_affinity(desc);
 125                 }
 126         }
 127         else {
 128                 desc->status |= IRQ_MOVE_PENDING;
 129                 cpumask_copy(desc->pending_mask, cpumask);
 130         }
 131 #else
 132         if (!chip->irq_set_affinity(&desc->irq_data, cpumask, false)) {
 133                 cpumask_copy(desc->irq_data.affinity, cpumask);
 134                 irq_set_thread_affinity(desc);
 135         }
 136 #endif
 137         if (desc->affinity_notify) {
 138                 kref_get(&desc->affinity_notify->kref);
 139                 schedule_work(&desc->affinity_notify->work);
 140         }
 141         desc->status |= IRQ_AFFINITY_SET;
 142         raw_spin_unlock_irqrestore(&desc->lock, flags);
 143         return 0;
 144 }
 145
 146 int irq_set_affinity_hint(unsigned int irq, const struct cpumask *m)
 147 {
 148         struct irq_desc *desc = irq_to_desc(irq);
 149         unsigned long flags;
 150
 151         if (!desc)
 152                 return -EINVAL;
 153
 154         raw_spin_lock_irqsave(&desc->lock, flags);
 155         desc->affinity_hint = m;
 156         raw_spin_unlock_irqrestore(&desc->lock, flags);
 157
 158         return 0;
 159 }
 160 EXPORT_SYMBOL_GPL(irq_set_affinity_hint);
 161
 162 static void irq_affinity_notify(struct work_struct *work)
 163 {
 164         struct irq_affinity_notify *notify =
 165                 container_of(work, struct irq_affinity_notify, work);
 166         struct irq_desc *desc = irq_to_desc(notify->irq);
 167         cpumask_var_t cpumask;
 168         unsigned long flags;
 169
 170         if (!desc)
 171                 goto out;
 172
 173         if (!alloc_cpumask_var(&cpumask, GFP_KERNEL))
 174                 goto out;
 175
 176         raw_spin_lock_irqsave(&desc->lock, flags);
 177 #ifdef CONFIG_GENERIC_PENDING_IRQ
 178         if (desc->status & IRQ_MOVE_PENDING)
 179                 cpumask_copy(cpumask, desc->pending_mask);
 180         else
 181 #endif
 182                 cpumask_copy(cpumask, desc->irq_data.affinity);
 183         raw_spin_unlock_irqrestore(&desc->lock, flags);
 184
 185         notify->notify(notify, cpumask);
 186
 187         free_cpumask_var(cpumask);
 188 out:
 189         kref_put(&notify->kref, notify->release);
 190 }
 191
 192 /**
 193  *      irq_set_affinity_notifier - control notification of IRQ affinity changes
 194  *      @irq:           Interrupt for which to enable/disable notification
 195  *      @notify:        Context for notification, or %NULL to disable
 196  *                      notification.  Function pointers must be initialised;
 197  *                      the other fields will be initialised by this function.
 198  *
 199  *      Must be called in process context.  Notification may only be enabled
 200  *      after the IRQ is allocated and must be disabled before the IRQ is
 201  *      freed using free_irq().
 202  */
 203 int
 204 irq_set_affinity_notifier(unsigned int irq, struct irq_affinity_notify *notify)
 205 {
 206         struct irq_desc *desc = irq_to_desc(irq);
 207         struct irq_affinity_notify *old_notify;
 208         unsigned long flags;
 209
 210         /* The release function is promised process context */
 211         might_sleep();
 212
 213         if (!desc)
 214                 return -EINVAL;
 215
 216         /* Complete initialisation of *notify */
 217         if (notify) {
 218                 notify->irq = irq;
 219                 kref_init(&notify->kref);
 220                 INIT_WORK(&notify->work, irq_affinity_notify);
 221         }
 222
 223         raw_spin_lock_irqsave(&desc->lock, flags);
 224         old_notify = desc->affinity_notify;
 225         desc->affinity_notify = notify;
 226         raw_spin_unlock_irqrestore(&desc->lock, flags);
 227
 228         if (old_notify)
 229                 kref_put(&old_notify->kref, old_notify->release);
 230
 231         return 0;
 232 }
 233 EXPORT_SYMBOL_GPL(irq_set_affinity_notifier);
 234
 235 #ifndef CONFIG_AUTO_IRQ_AFFINITY
 236 /*
 237  * Generic version of the affinity autoselector.
 238  */
 239 static int setup_affinity(unsigned int irq, struct irq_desc *desc)
 240 {
 241         if (!irq_can_set_affinity(irq))
 242                 return 0;
 243
 244         /*
 245          * Preserve an userspace affinity setup, but make sure that
 246          * one of the targets is online.
 247          */
 248         if (desc->status & (IRQ_AFFINITY_SET | IRQ_NO_BALANCING)) {
 249                 if (cpumask_any_and(desc->irq_data.affinity, cpu_online_mask)
 250                     < nr_cpu_ids)
 251                         goto set_affinity;
 252                 else
 253                         desc->status &= ~IRQ_AFFINITY_SET;
 254         }
 255
 256         cpumask_and(desc->irq_data.affinity, cpu_online_mask, irq_default_affinity);
 257 set_affinity:
 258         desc->irq_data.chip->irq_set_affinity(&desc->irq_data, desc->irq_data.affinity, false);
 259
 260         return 0;
 261 }
 262 #else
 263 static inline int setup_affinity(unsigned int irq, struct irq_desc *d)
 264 {
 265         return irq_select_affinity(irq);
 266 }
 267 #endif
 268
 269 /*
 270  * Called when affinity is set via /proc/irq
 271  */
 272 int irq_select_affinity_usr(unsigned int irq)
 273 {
 274         struct irq_desc *desc = irq_to_desc(irq);
 275         unsigned long flags;
 276         int ret;
 277
 278         raw_spin_lock_irqsave(&desc->lock, flags);
 279         ret = setup_affinity(irq, desc);
 280         if (!ret)
 281                 irq_set_thread_affinity(desc);
 282         raw_spin_unlock_irqrestore(&desc->lock, flags);
 283
 284         return ret;
 285 }
 286
 287 #else
 288 static inline int setup_affinity(unsigned int irq, struct irq_desc *desc)
 289 {
 290         return 0;
 291 }
 292 #endif
 293
 294 void __disable_irq(struct irq_desc *desc, unsigned int irq, bool suspend)
 295 {
 296         if (suspend) {
 297                 if (!desc->action || (desc->action->flags & IRQF_NO_SUSPEND))
 298                         return;
 299                 desc->status |= IRQ_SUSPENDED;
 300         }
 301
 302         if (!desc->depth++) {
 303                 desc->status |= IRQ_DISABLED;
 304                 desc->irq_data.chip->irq_disable(&desc->irq_data);
 305         }
 306 }
 307
 308 /**
 309  *      disable_irq_nosync - disable an irq without waiting
 310  *      @irq: Interrupt to disable
 311  *
 312  *      Disable the selected interrupt line.  Disables and Enables are
 313  *      nested.
 314  *      Unlike disable_irq(), this function does not ensure existing
 315  *      instances of the IRQ handler have completed before returning.
 316  *
 317  *      This function may be called from IRQ context.
 318  */
 319 void disable_irq_nosync(unsigned int irq)
 320 {
 321         struct irq_desc *desc = irq_to_desc(irq);
 322         unsigned long flags;
 323
 324         if (!desc)
 325                 return;
 326
 327         chip_bus_lock(desc);
 328         raw_spin_lock_irqsave(&desc->lock, flags);
 329         __disable_irq(desc, irq, false);
 330         raw_spin_unlock_irqrestore(&desc->lock, flags);
 331         chip_bus_sync_unlock(desc);
 332 }
 333 EXPORT_SYMBOL(disable_irq_nosync);
 334
 335 /**
 336  *      disable_irq - disable an irq and wait for completion
 337  *      @irq: Interrupt to disable
 338  *
 339  *      Disable the selected interrupt line.  Enables and Disables are
 340  *      nested.
 341  *      This function waits for any pending IRQ handlers for this interrupt
 342  *      to complete before returning. If you use this function while
 343  *      holding a resource the IRQ handler may need you will deadlock.
 344  *
 345  *      This function may be called - with care - from IRQ context.
 346  */
 347 void disable_irq(unsigned int irq)
 348 {
 349         struct irq_desc *desc = irq_to_desc(irq);
 350
 351         if (!desc)
 352                 return;
 353
 354         disable_irq_nosync(irq);
 355         if (desc->action)
 356                 synchronize_irq(irq);
 357 }
 358 EXPORT_SYMBOL(disable_irq);
 359
 360 void __enable_irq(struct irq_desc *desc, unsigned int irq, bool resume)
 361 {
 362         if (resume)
 363                 desc->status &= ~IRQ_SUSPENDED;
 364
 365         switch (desc->depth) {
 366         case 0:
 367  err_out:
 368                 WARN(1, KERN_WARNING "Unbalanced enable for IRQ %d\n", irq);
 369                 break;
 370         case 1: {
 371                 unsigned int status = desc->status & ~IRQ_DISABLED;
 372
 373                 if (desc->status & IRQ_SUSPENDED)
 374                         goto err_out;
 375                 /* Prevent probing on this irq: */
 376                 desc->status = status | IRQ_NOPROBE;
 377                 check_irq_resend(desc, irq);
 378                 /* fall-through */
 379         }
 380         default:
 381                 desc->depth--;
 382         }
 383 }
 384
 385 /**
 386  *      enable_irq - enable handling of an irq
 387  *      @irq: Interrupt to enable
 388  *
 389  *      Undoes the effect of one call to disable_irq().  If this
 390  *      matches the last disable, processing of interrupts on this
 391  *      IRQ line is re-enabled.
 392  *
 393  *      This function may be called from IRQ context only when
 394  *      desc->irq_data.chip->bus_lock and desc->chip->bus_sync_unlock are NULL !
 395  */
 396 void enable_irq(unsigned int irq)
 397 {
 398         struct irq_desc *desc = irq_to_desc(irq);
 399         unsigned long flags;
 400
 401         if (!desc)
 402                 return;
 403
 404         if (WARN(!desc->irq_data.chip || !desc->irq_data.chip->irq_enable,
 405             KERN_ERR "enable_irq before setup/request_irq: irq %u\n", irq))
 406                 return;
 407
 408         chip_bus_lock(desc);
 409         raw_spin_lock_irqsave(&desc->lock, flags);
 410         __enable_irq(desc, irq, false);
 411         raw_spin_unlock_irqrestore(&desc->lock, flags);
 412         chip_bus_sync_unlock(desc);
 413 }
 414 EXPORT_SYMBOL(enable_irq);
 415
 416 static int set_irq_wake_real(unsigned int irq, unsigned int on)
 417 {
 418         struct irq_desc *desc = irq_to_desc(irq);
 419         int ret = -ENXIO;
 420
 421         if (desc->irq_data.chip->irq_set_wake)
 422                 ret = desc->irq_data.chip->irq_set_wake(&desc->irq_data, on);
 423
 424         return ret;
 425 }
 426
 427 /**
 428  *      set_irq_wake - control irq power management wakeup
 429  *      @irq:   interrupt to control
 430  *      @on:    enable/disable power management wakeup
 431  *
 432  *      Enable/disable power management wakeup mode, which is
 433  *      disabled by default.  Enables and disables must match,
 434  *      just as they match for non-wakeup mode support.
 435  *
 436  *      Wakeup mode lets this IRQ wake the system from sleep
 437  *      states like "suspend to RAM".
 438  */
 439 int set_irq_wake(unsigned int irq, unsigned int on)
 440 {
 441         struct irq_desc *desc = irq_to_desc(irq);
 442         unsigned long flags;
 443         int ret = 0;
 444
 445         /* wakeup-capable irqs can be shared between drivers that
 446          * don't need to have the same sleep mode behaviors.
 447          */
 448         raw_spin_lock_irqsave(&desc->lock, flags);
 449         if (on) {
 450                 if (desc->wake_depth++ == 0) {
 451                         ret = set_irq_wake_real(irq, on);
 452                         if (ret)
 453                                 desc->wake_depth = 0;
 454                         else
 455                                 desc->status |= IRQ_WAKEUP;
 456                 }
 457         } else {
 458                 if (desc->wake_depth == 0) {
 459                         WARN(1, "Unbalanced IRQ %d wake disable\n", irq);
 460                 } else if (--desc->wake_depth == 0) {
 461                         ret = set_irq_wake_real(irq, on);
 462                         if (ret)
 463                                 desc->wake_depth = 1;
 464                         else
 465                                 desc->status &= ~IRQ_WAKEUP;
 466                 }
 467         }
 468
 469         raw_spin_unlock_irqrestore(&desc->lock, flags);
 470         return ret;
 471 }
 472 EXPORT_SYMBOL(set_irq_wake);
 473
 474 /*
 475  * Internal function that tells the architecture code whether a
 476  * particular irq has been exclusively allocated or is available
 477  * for driver use.
 478  */
 479 int can_request_irq(unsigned int irq, unsigned long irqflags)
 480 {
 481         struct irq_desc *desc = irq_to_desc(irq);
 482         struct irqaction *action;
 483         unsigned long flags;
 484
 485         if (!desc)
 486                 return 0;
 487
 488         if (desc->status & IRQ_NOREQUEST)
 489                 return 0;
 490
 491         raw_spin_lock_irqsave(&desc->lock, flags);
 492         action = desc->action;
 493         if (action)
 494                 if (irqflags & action->flags & IRQF_SHARED)
 495                         action = NULL;
 496
 497         raw_spin_unlock_irqrestore(&desc->lock, flags);
 498
 499         return !action;
 500 }
 501
 502 void compat_irq_chip_set_default_handler(struct irq_desc *desc)
 503 {
 504         /*
 505          * If the architecture still has not overriden
 506          * the flow handler then zap the default. This
 507          * should catch incorrect flow-type setting.
 508          */
 509         if (desc->handle_irq == &handle_bad_irq)
 510                 desc->handle_irq = NULL;
 511 }
 512
 513 int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
 514                       unsigned long flags)
 515 {
 516         int ret;
 517         struct irq_chip *chip = desc->irq_data.chip;
 518
 519         if (!chip || !chip->irq_set_type) {
 520                 /*
 521                  * IRQF_TRIGGER_* but the PIC does not support multiple
 522                  * flow-types?
 523                  */
 524                 pr_debug("No set_type function for IRQ %d (%s)\n", irq,
 525                                 chip ? (chip->name ? : "unknown") : "unknown");
 526                 return 0;
 527         }
 528
 529         /* caller masked out all except trigger mode flags */
 530         ret = chip->irq_set_type(&desc->irq_data, flags);
 531
 532         if (ret)
 533                 pr_err("setting trigger mode %lu for irq %u failed (%pF)\n",
 534                        flags, irq, chip->irq_set_type);
 535         else {
 536                 if (flags & (IRQ_TYPE_LEVEL_LOW | IRQ_TYPE_LEVEL_HIGH))
 537                         flags |= IRQ_LEVEL;
 538                 /* note that IRQF_TRIGGER_MASK == IRQ_TYPE_SENSE_MASK */
 539                 desc->status &= ~(IRQ_LEVEL | IRQ_TYPE_SENSE_MASK);
 540                 desc->status |= flags;
 541
 542                 if (chip != desc->irq_data.chip)
 543                         irq_chip_set_defaults(desc->irq_data.chip);
 544         }
 545
 546         return ret;
 547 }
 548
 549 /*
 550  * Default primary interrupt handler for threaded interrupts. Is
 551  * assigned as primary handler when request_threaded_irq is called
 552  * with handler == NULL. Useful for oneshot interrupts.
 553  */
 554 static irqreturn_t irq_default_primary_handler(int irq, void *dev_id)
 555 {
 556         return IRQ_WAKE_THREAD;
 557 }
 558
 559 /*
 560  * Primary handler for nested threaded interrupts. Should never be
 561  * called.
 562  */
 563 static irqreturn_t irq_nested_primary_handler(int irq, void *dev_id)
 564 {
 565         WARN(1, "Primary handler called for nested irq %d\n", irq);
 566         return IRQ_NONE;
 567 }
 568
 569 static int irq_wait_for_interrupt(struct irqaction *action)
 570 {
 571         while (!kthread_should_stop()) {
 572                 set_current_state(TASK_INTERRUPTIBLE);
 573
 574                 if (test_and_clear_bit(IRQTF_RUNTHREAD,
 575                                        &action->thread_flags)) {
 576                         __set_current_state(TASK_RUNNING);
 577                         return 0;
 578                 }
 579                 schedule();
 580         }
 581         return -1;
 582 }
 583
 584 /*
 585  * Oneshot interrupts keep the irq line masked until the threaded
 586  * handler finished. unmask if the interrupt has not been disabled and
 587  * is marked MASKED.
 588  */
 589 static void irq_finalize_oneshot(unsigned int irq, struct irq_desc *desc)
 590 {
 591 again:
 592         chip_bus_lock(desc);
 593         raw_spin_lock_irq(&desc->lock);
 594
 595         /*
 596          * Implausible though it may be we need to protect us against
 597          * the following scenario:
 598          *
 599          * The thread is faster done than the hard interrupt handler
 600          * on the other CPU. If we unmask the irq line then the
 601          * interrupt can come in again and masks the line, leaves due
 602          * to IRQ_INPROGRESS and the irq line is masked forever.
 603          */
 604         if (unlikely(desc->status & IRQ_INPROGRESS)) {
 605                 raw_spin_unlock_irq(&desc->lock);
 606                 chip_bus_sync_unlock(desc);
 607                 cpu_relax();
 608                 goto again;
 609         }
 610
 611         if (!(desc->status & IRQ_DISABLED) && (desc->status & IRQ_MASKED)) {
 612                 desc->status &= ~IRQ_MASKED;
 613                 desc->irq_data.chip->irq_unmask(&desc->irq_data);
 614         }
 615         raw_spin_unlock_irq(&desc->lock);
 616         chip_bus_sync_unlock(desc);
 617 }
 618
 619 #ifdef CONFIG_SMP
 620 /*
 621  * Check whether we need to change the affinity of the interrupt thread.
 622  */
 623 static void
 624 irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action)
 625 {
 626         cpumask_var_t mask;
 627
 628         if (!test_and_clear_bit(IRQTF_AFFINITY, &action->thread_flags))
 629                 return;
 630
 631         /*
 632          * In case we are out of memory we set IRQTF_AFFINITY again and
 633          * try again next time
 634          */
 635         if (!alloc_cpumask_var(&mask, GFP_KERNEL)) {
 636                 set_bit(IRQTF_AFFINITY, &action->thread_flags);
 637                 return;
 638         }
 639
 640         raw_spin_lock_irq(&desc->lock);
 641         cpumask_copy(mask, desc->irq_data.affinity);
 642         raw_spin_unlock_irq(&desc->lock);
 643
 644         set_cpus_allowed_ptr(current, mask);
 645         free_cpumask_var(mask);
 646 }
 647 #else
 648 static inline void
 649 irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action) { }
 650 #endif
 651
 652 /*
 653  * Interrupt handler thread
 654  */
 655 static int irq_thread(void *data)
 656 {
 657         static const struct sched_param param = {
 658                 .sched_priority = MAX_USER_RT_PRIO/2,
 659         };
 660         struct irqaction *action = data;
 661         struct irq_desc *desc = irq_to_desc(action->irq);
 662         int wake, oneshot = desc->status & IRQ_ONESHOT;
 663
 664         sched_setscheduler(current, SCHED_FIFO, &param);
 665         current->irqaction = action;
 666
 667         while (!irq_wait_for_interrupt(action)) {
 668
 669                 irq_thread_check_affinity(desc, action);
 670
 671                 atomic_inc(&desc->threads_active);
 672
 673                 raw_spin_lock_irq(&desc->lock);
 674                 if (unlikely(desc->status & IRQ_DISABLED)) {
 675                         /*
 676                          * CHECKME: We might need a dedicated
 677                          * IRQ_THREAD_PENDING flag here, which
 678                          * retriggers the thread in check_irq_resend()
 679                          * but AFAICT IRQ_PENDING should be fine as it
 680                          * retriggers the interrupt itself --- tglx
 681                          */
 682                         desc->status |= IRQ_PENDING;
 683                         raw_spin_unlock_irq(&desc->lock);
 684                 } else {
 685                         raw_spin_unlock_irq(&desc->lock);
 686
 687                         action->thread_fn(action->irq, action->dev_id);
 688
 689                         if (oneshot)
 690                                 irq_finalize_oneshot(action->irq, desc);
 691                 }
 692
 693                 wake = atomic_dec_and_test(&desc->threads_active);
 694
 695                 if (wake && waitqueue_active(&desc->wait_for_threads))
 696                         wake_up(&desc->wait_for_threads);
 697         }
 698
 699         /*
 700          * Clear irqaction. Otherwise exit_irq_thread() would make
 701          * fuzz about an active irq thread going into nirvana.
 702          */
 703         current->irqaction = NULL;
 704         return 0;
 705 }
 706
 707 /*
 708  * Called from do_exit()
 709  */
 710 void exit_irq_thread(void)
 711 {
 712         struct task_struct *tsk = current;
 713
 714         if (!tsk->irqaction)
 715                 return;
 716
 717         printk(KERN_ERR
 718                "exiting task \"%s\" (%d) is an active IRQ thread (irq %d)\n",
 719                tsk->comm ? tsk->comm : "", tsk->pid, tsk->irqaction->irq);
 720
 721         /*
 722          * Set the THREAD DIED flag to prevent further wakeups of the
 723          * soon to be gone threaded handler.
 724          */
 725         set_bit(IRQTF_DIED, &tsk->irqaction->flags);
 726 }
 727
 728 /*
 729  * Internal function to register an irqaction - typically used to
 730  * allocate special interrupts that are part of the architecture.
 731  */
 732 static int
 733 __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
 734 {
 735         struct irqaction *old, **old_ptr;
 736         const char *old_name = NULL;
 737         unsigned long flags;
 738         int nested, shared = 0;
 739         int ret;
 740
 741         if (!desc)
 742                 return -EINVAL;
 743
 744         if (desc->irq_data.chip == &no_irq_chip)
 745                 return -ENOSYS;
 746         /*
 747          * Some drivers like serial.c use request_irq() heavily,
 748          * so we have to be careful not to interfere with a
 749          * running system.
 750          */
 751         if (new->flags & IRQF_SAMPLE_RANDOM) {
 752                 /*
 753                  * This function might sleep, we want to call it first,
 754                  * outside of the atomic block.
 755                  * Yes, this might clear the entropy pool if the wrong
 756                  * driver is attempted to be loaded, without actually
 757                  * installing a new handler, but is this really a problem,
 758                  * only the sysadmin is able to do this.
 759                  */
 760                 rand_initialize_irq(irq);
 761         }
 762
 763         /* Oneshot interrupts are not allowed with shared */
 764         if ((new->flags & IRQF_ONESHOT) && (new->flags & IRQF_SHARED))
 765                 return -EINVAL;
 766
 767         /*
 768          * Check whether the interrupt nests into another interrupt
 769          * thread.
 770          */
 771         nested = desc->status & IRQ_NESTED_THREAD;
 772         if (nested) {
 773                 if (!new->thread_fn)
 774                         return -EINVAL;
 775                 /*
 776                  * Replace the primary handler which was provided from
 777                  * the driver for non nested interrupt handling by the
 778                  * dummy function which warns when called.
 779                  */
 780                 new->handler = irq_nested_primary_handler;
 781         }
 782
 783         /*
 784          * Create a handler thread when a thread function is supplied
 785          * and the interrupt does not nest into another interrupt
 786          * thread.
 787          */
 788         if (new->thread_fn && !nested) {
 789                 struct task_struct *t;
 790
 791                 t = kthread_create(irq_thread, new, "irq/%d-%s", irq,
 792                                    new->name);
 793                 if (IS_ERR(t))
 794                         return PTR_ERR(t);
 795                 /*
 796                  * We keep the reference to the task struct even if
 797                  * the thread dies to avoid that the interrupt code
 798                  * references an already freed task_struct.
 799                  */
 800                 get_task_struct(t);
 801                 new->thread = t;
 802         }
 803
 804         /*
 805          * The following block of code has to be executed atomically
 806          */
 807         raw_spin_lock_irqsave(&desc->lock, flags);
 808         old_ptr = &desc->action;
 809         old = *old_ptr;
 810         if (old) {
 811                 /*
 812                  * Can't share interrupts unless both agree to and are
 813                  * the same type (level, edge, polarity). So both flag
 814                  * fields must have IRQF_SHARED set and the bits which
 815                  * set the trigger type must match.
 816                  */
 817                 if (!((old->flags & new->flags) & IRQF_SHARED) ||
 818                     ((old->flags ^ new->flags) & IRQF_TRIGGER_MASK)) {
 819                         old_name = old->name;
 820                         goto mismatch;
 821                 }
 822
 823 #if defined(CONFIG_IRQ_PER_CPU)
 824                 /* All handlers must agree on per-cpuness */
 825                 if ((old->flags & IRQF_PERCPU) !=
 826                     (new->flags & IRQF_PERCPU))
 827                         goto mismatch;
 828 #endif
 829
 830                 /* add new interrupt at end of irq queue */
 831                 do {
 832                         old_ptr = &old->next;
 833                         old = *old_ptr;
 834                 } while (old);
 835                 shared = 1;
 836         }
 837
 838         if (!shared) {
 839                 irq_chip_set_defaults(desc->irq_data.chip);
 840
 841                 init_waitqueue_head(&desc->wait_for_threads);
 842
 843                 /* Setup the type (level, edge polarity) if configured: */
 844                 if (new->flags & IRQF_TRIGGER_MASK) {
 845                         ret = __irq_set_trigger(desc, irq,
 846                                         new->flags & IRQF_TRIGGER_MASK);
 847
 848                         if (ret)
 849                                 goto out_thread;
 850                 } else
 851                         compat_irq_chip_set_default_handler(desc);
 852 #if defined(CONFIG_IRQ_PER_CPU)
 853                 if (new->flags & IRQF_PERCPU)
 854                         desc->status |= IRQ_PER_CPU;
 855 #endif
 856
 857                 desc->status &= ~(IRQ_AUTODETECT | IRQ_WAITING | IRQ_ONESHOT |
 858                                   IRQ_INPROGRESS | IRQ_SPURIOUS_DISABLED);
 859
 860                 if (new->flags & IRQF_ONESHOT)
 861                         desc->status |= IRQ_ONESHOT;
 862
 863                 if (!(desc->status & IRQ_NOAUTOEN)) {
 864                         desc->depth = 0;
 865                         desc->status &= ~IRQ_DISABLED;
 866                         desc->irq_data.chip->irq_startup(&desc->irq_data);
 867                 } else
 868                         /* Undo nested disables: */
 869                         desc->depth = 1;
 870
 871                 /* Exclude IRQ from balancing if requested */
 872                 if (new->flags & IRQF_NOBALANCING)
 873                         desc->status |= IRQ_NO_BALANCING;
 874
 875                 /* Set default affinity mask once everything is setup */
 876                 setup_affinity(irq, desc);
 877
 878         } else if ((new->flags & IRQF_TRIGGER_MASK)
 879                         && (new->flags & IRQF_TRIGGER_MASK)
 880                                 != (desc->status & IRQ_TYPE_SENSE_MASK)) {
 881                 /* hope the handler works with the actual trigger mode... */
 882                 pr_warning("IRQ %d uses trigger mode %d; requested %d\n",
 883                                 irq, (int)(desc->status & IRQ_TYPE_SENSE_MASK),
 884                                 (int)(new->flags & IRQF_TRIGGER_MASK));
 885         }
 886
 887         new->irq = irq;
 888         *old_ptr = new;
 889
 890         /* Reset broken irq detection when installing new handler */
 891         desc->irq_count = 0;
 892         desc->irqs_unhandled = 0;
 893
 894         /*
 895          * Check whether we disabled the irq via the spurious handler
 896          * before. Reenable it and give it another chance.
 897          */
 898         if (shared && (desc->status & IRQ_SPURIOUS_DISABLED)) {
 899                 desc->status &= ~IRQ_SPURIOUS_DISABLED;
 900                 __enable_irq(desc, irq, false);
 901         }
 902
 903         raw_spin_unlock_irqrestore(&desc->lock, flags);
 904
 905         /*
 906          * Strictly no need to wake it up, but hung_task complains
 907          * when no hard interrupt wakes the thread up.
 908          */
 909         if (new->thread)
 910                 wake_up_process(new->thread);
 911
 912         register_irq_proc(irq, desc);
 913         new->dir = NULL;
 914         register_handler_proc(irq, new);
 915
 916         return 0;
 917
 918 mismatch:
 919 #ifdef CONFIG_DEBUG_SHIRQ
 920         if (!(new->flags & IRQF_PROBE_SHARED)) {
 921                 printk(KERN_ERR "IRQ handler type mismatch for IRQ %d\n", irq);
 922                 if (old_name)
 923                         printk(KERN_ERR "current handler: %s\n", old_name);
 924                 dump_stack();
 925         }
 926 #endif
 927         ret = -EBUSY;
 928
 929 out_thread:
 930         raw_spin_unlock_irqrestore(&desc->lock, flags);
 931         if (new->thread) {
 932                 struct task_struct *t = new->thread;
 933
 934                 new->thread = NULL;
 935                 if (likely(!test_bit(IRQTF_DIED, &new->thread_flags)))
 936                         kthread_stop(t);
 937                 put_task_struct(t);
 938         }
 939         return ret;
 940 }
 941
 942 /**
 943  *      setup_irq - setup an interrupt
 944  *      @irq: Interrupt line to setup
 945  *      @act: irqaction for the interrupt
 946  *
 947  * Used to statically setup interrupts in the early boot process.
 948  */
 949 int setup_irq(unsigned int irq, struct irqaction *act)
 950 {
 951         struct irq_desc *desc = irq_to_desc(irq);
 952
 953         return __setup_irq(irq, desc, act);
 954 }
 955 EXPORT_SYMBOL_GPL(setup_irq);
 956
 957  /*
 958  * Internal function to unregister an irqaction - used to free
 959  * regular and special interrupts that are part of the architecture.
 960  */
 961 static struct irqaction *__free_irq(unsigned int irq, void *dev_id)
 962 {
 963         struct irq_desc *desc = irq_to_desc(irq);
 964         struct irqaction *action, **action_ptr;
 965         unsigned long flags;
 966
 967         WARN(in_interrupt(), "Trying to free IRQ %d from IRQ context!\n", irq);
 968
 969         if (!desc)
 970                 return NULL;
 971
 972         raw_spin_lock_irqsave(&desc->lock, flags);
 973
 974         /*
 975          * There can be multiple actions per IRQ descriptor, find the right
 976          * one based on the dev_id:
 977          */
 978         action_ptr = &desc->action;
 979         for (;;) {
 980                 action = *action_ptr;
 981
 982                 if (!action) {
 983                         WARN(1, "Trying to free already-free IRQ %d\n", irq);
 984                         raw_spin_unlock_irqrestore(&desc->lock, flags);
 985
 986                         return NULL;
 987                 }
 988
 989                 if (action->dev_id == dev_id)
 990                         break;
 991                 action_ptr = &action->next;
 992         }
 993
 994         /* Found it - now remove it from the list of entries: */
 995         *action_ptr = action->next;
 996
 997         /* Currently used only by UML, might disappear one day: */
 998 #ifdef CONFIG_IRQ_RELEASE_METHOD
 999         if (desc->irq_data.chip->release)
1000                 desc->irq_data.chip->release(irq, dev_id);
1001 #endif
1002
1003         /* If this was the last handler, shut down the IRQ line: */
1004         if (!desc->action) {
1005                 desc->status |= IRQ_DISABLED;
1006                 if (desc->irq_data.chip->irq_shutdown)
1007                         desc->irq_data.chip->irq_shutdown(&desc->irq_data);
1008                 else
1009                         desc->irq_data.chip->irq_disable(&desc->irq_data);
1010         }
1011
1012 #ifdef CONFIG_SMP
1013         /* make sure affinity_hint is cleaned up */
1014         if (WARN_ON_ONCE(desc->affinity_hint))
1015                 desc->affinity_hint = NULL;
1016 #endif
1017
1018         raw_spin_unlock_irqrestore(&desc->lock, flags);
1019
1020         unregister_handler_proc(irq, action);
1021
1022         /* Make sure it's not being used on another CPU: */
1023         synchronize_irq(irq);
1024
1025 #ifdef CONFIG_DEBUG_SHIRQ
1026         /*
1027          * It's a shared IRQ -- the driver ought to be prepared for an IRQ
1028          * event to happen even now it's being freed, so let's make sure that
1029          * is so by doing an extra call to the handler ....
1030          *
1031          * ( We do this after actually deregistering it, to make sure that a
1032          *   'real' IRQ doesn't run in * parallel with our fake. )
1033          */
1034         if (action->flags & IRQF_SHARED) {
1035                 local_irq_save(flags);
1036                 action->handler(irq, dev_id);
1037                 local_irq_restore(flags);
1038         }
1039 #endif
1040
1041         if (action->thread) {
1042                 if (!test_bit(IRQTF_DIED, &action->thread_flags))
1043                         kthread_stop(action->thread);
1044                 put_task_struct(action->thread);
1045         }
1046
1047         return action;
1048 }
1049
1050 /**
1051  *      remove_irq - free an interrupt
1052  *      @irq: Interrupt line to free
1053  *      @act: irqaction for the interrupt
1054  *
1055  * Used to remove interrupts statically setup by the early boot process.
1056  */
1057 void remove_irq(unsigned int irq, struct irqaction *act)
1058 {
1059         __free_irq(irq, act->dev_id);
1060 }
1061 EXPORT_SYMBOL_GPL(remove_irq);
1062
1063 /**
1064  *      free_irq - free an interrupt allocated with request_irq
1065  *      @irq: Interrupt line to free
1066  *      @dev_id: Device identity to free
1067  *
1068  *      Remove an interrupt handler. The handler is removed and if the
1069  *      interrupt line is no longer in use by any driver it is disabled.
1070  *      On a shared IRQ the caller must ensure the interrupt is disabled
1071  *      on the card it drives before calling this function. The function
1072  *      does not return until any executing interrupts for this IRQ
1073  *      have completed.
1074  *
1075  *      This function must not be called from interrupt context.
1076  */
1077 void free_irq(unsigned int irq, void *dev_id)
1078 {
1079         struct irq_desc *desc = irq_to_desc(irq);
1080
1081         if (!desc)
1082                 return;
1083
1084 #ifdef CONFIG_SMP
1085         if (WARN_ON(desc->affinity_notify))
1086                 desc->affinity_notify = NULL;
1087 #endif
1088
1089         chip_bus_lock(desc);
1090         kfree(__free_irq(irq, dev_id));
1091         chip_bus_sync_unlock(desc);
1092 }
1093 EXPORT_SYMBOL(free_irq);
1094
1095 /**
1096  *      request_threaded_irq - allocate an interrupt line
1097  *      @irq: Interrupt line to allocate
1098  *      @handler: Function to be called when the IRQ occurs.
1099  *                Primary handler for threaded interrupts
1100  *                If NULL and thread_fn != NULL the default
1101  *                primary handler is installed
1102  *      @thread_fn: Function called from the irq handler thread
1103  *                  If NULL, no irq thread is created
1104  *      @irqflags: Interrupt type flags
1105  *      @devname: An ascii name for the claiming device
1106  *      @dev_id: A cookie passed back to the handler function
1107  *
1108  *      This call allocates interrupt resources and enables the
1109  *      interrupt line and IRQ handling. From the point this
1110  *      call is made your handler function may be invoked. Since
1111  *      your handler function must clear any interrupt the board
1112  *      raises, you must take care both to initialise your hardware
1113  *      and to set up the interrupt handler in the right order.
1114  *
1115  *      If you want to set up a threaded irq handler for your device
1116  *      then you need to supply @handler and @thread_fn. @handler ist
1117  *      still called in hard interrupt context and has to check
1118  *      whether the interrupt originates from the device. If yes it
1119  *      needs to disable the interrupt on the device and return
1120  *      IRQ_WAKE_THREAD which will wake up the handler thread and run
1121  *      @thread_fn. This split handler design is necessary to support
1122  *      shared interrupts.
1123  *
1124  *      Dev_id must be globally unique. Normally the address of the
1125  *      device data structure is used as the cookie. Since the handler
1126  *      receives this value it makes sense to use it.
1127  *
1128  *      If your interrupt is shared you must pass a non NULL dev_id
1129  *      as this is required when freeing the interrupt.
1130  *
1131  *      Flags:
1132  *
1133  *      IRQF_SHARED             Interrupt is shared
1134  *      IRQF_SAMPLE_RANDOM      The interrupt can be used for entropy
1135  *      IRQF_TRIGGER_*          Specify active edge(s) or level
1136  *
1137  */
1138 int request_threaded_irq(unsigned int irq, irq_handler_t handler,
1139                          irq_handler_t thread_fn, unsigned long irqflags,
1140                          const char *devname, void *dev_id)
1141 {
1142         struct irqaction *action;
1143         struct irq_desc *desc;
1144         int retval;
1145
1146         /*
1147          * Sanity-check: shared interrupts must pass in a real dev-ID,
1148          * otherwise we'll have trouble later trying to figure out
1149          * which interrupt is which (messes up the interrupt freeing
1150          * logic etc).
1151          */
1152         if ((irqflags & IRQF_SHARED) && !dev_id)
1153                 return -EINVAL;
1154
1155         desc = irq_to_desc(irq);
1156         if (!desc)
1157                 return -EINVAL;
1158
1159         if (desc->status & IRQ_NOREQUEST)
1160                 return -EINVAL;
1161
1162         if (!handler) {
1163                 if (!thread_fn)
1164                         return -EINVAL;
1165                 handler = irq_default_primary_handler;
1166         }
1167
1168         action = kzalloc(sizeof(struct irqaction), GFP_KERNEL);
1169         if (!action)
1170                 return -ENOMEM;
1171
1172         action->handler = handler;
1173         action->thread_fn = thread_fn;
1174         action->flags = irqflags;
1175         action->name = devname;
1176         action->dev_id = dev_id;
1177
1178         chip_bus_lock(desc);
1179         retval = __setup_irq(irq, desc, action);
1180         chip_bus_sync_unlock(desc);
1181
1182         if (retval)
1183                 kfree(action);
1184
1185 #ifdef CONFIG_DEBUG_SHIRQ_FIXME
1186         if (!retval && (irqflags & IRQF_SHARED)) {
1187                 /*
1188                  * It's a shared IRQ -- the driver ought to be prepared for it
1189                  * to happen immediately, so let's make sure....
1190                  * We disable the irq to make sure that a 'real' IRQ doesn't
1191                  * run in parallel with our fake.
1192                  */
1193                 unsigned long flags;
1194
1195                 disable_irq(irq);
1196                 local_irq_save(flags);
1197
1198                 handler(irq, dev_id);
1199
1200                 local_irq_restore(flags);
1201                 enable_irq(irq);
1202         }
1203 #endif
1204         return retval;
1205 }
1206 EXPORT_SYMBOL(request_threaded_irq);
1207
1208 /**
1209  *      request_any_context_irq - allocate an interrupt line
1210  *      @irq: Interrupt line to allocate
1211  *      @handler: Function to be called when the IRQ occurs.
1212  *                Threaded handler for threaded interrupts.
1213  *      @flags: Interrupt type flags
1214  *      @name: An ascii name for the claiming device
1215  *      @dev_id: A cookie passed back to the handler function
1216  *
1217  *      This call allocates interrupt resources and enables the
1218  *      interrupt line and IRQ handling. It selects either a
1219  *      hardirq or threaded handling method depending on the
1220  *      context.
1221  *
1222  *      On failure, it returns a negative value. On success,
1223  *      it returns either IRQC_IS_HARDIRQ or IRQC_IS_NESTED.
1224  */
1225 int request_any_context_irq(unsigned int irq, irq_handler_t handler,
1226                             unsigned long flags, const char *name, void *dev_id)
1227 {
1228         struct irq_desc *desc = irq_to_desc(irq);
1229         int ret;
1230
1231         if (!desc)
1232                 return -EINVAL;
1233
1234         if (desc->status & IRQ_NESTED_THREAD) {
1235                 ret = request_threaded_irq(irq, NULL, handler,
1236                                            flags, name, dev_id);
1237                 return !ret ? IRQC_IS_NESTED : ret;
1238         }
1239
1240         ret = request_irq(irq, handler, flags, name, dev_id);
1241         return !ret ? IRQC_IS_HARDIRQ : ret;
1242 }
1243 EXPORT_SYMBOL_GPL(request_any_context_irq);