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