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