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 #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         raw_spin_lock_irqsave(&desc->lock, flags);
 185         ret = setup_affinity(irq, desc);
 186         if (!ret)
 187                 irq_set_thread_affinity(desc);
 188         raw_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         raw_spin_lock_irqsave(&desc->lock, flags);
 235         __disable_irq(desc, irq, false);
 236         raw_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         raw_spin_lock_irqsave(&desc->lock, flags);
 312         __enable_irq(desc, irq, false);
 313         raw_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         raw_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         raw_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         unsigned long flags;
 386
 387         if (!desc)
 388                 return 0;
 389
 390         if (desc->status & IRQ_NOREQUEST)
 391                 return 0;
 392
 393         raw_spin_lock_irqsave(&desc->lock, flags);
 394         action = desc->action;
 395         if (action)
 396                 if (irqflags & action->flags & IRQF_SHARED)
 397                         action = NULL;
 398
 399         raw_spin_unlock_irqrestore(&desc->lock, flags);
 400
 401         return !action;
 402 }
 403
 404 void compat_irq_chip_set_default_handler(struct irq_desc *desc)
 405 {
 406         /*
 407          * If the architecture still has not overriden
 408          * the flow handler then zap the default. This
 409          * should catch incorrect flow-type setting.
 410          */
 411         if (desc->handle_irq == &handle_bad_irq)
 412                 desc->handle_irq = NULL;
 413 }
 414
 415 int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
 416                 unsigned long flags)
 417 {
 418         int ret;
 419         struct irq_chip *chip = desc->chip;
 420
 421         if (!chip || !chip->set_type) {
 422                 /*
 423                  * IRQF_TRIGGER_* but the PIC does not support multiple
 424                  * flow-types?
 425                  */
 426                 pr_debug("No set_type function for IRQ %d (%s)\n", irq,
 427                                 chip ? (chip->name ? : "unknown") : "unknown");
 428                 return 0;
 429         }
 430
 431         /* caller masked out all except trigger mode flags */
 432         ret = chip->set_type(irq, flags);
 433
 434         if (ret)
 435                 pr_err("setting trigger mode %d for irq %u failed (%pF)\n",
 436                                 (int)flags, irq, chip->set_type);
 437         else {
 438                 if (flags & (IRQ_TYPE_LEVEL_LOW | IRQ_TYPE_LEVEL_HIGH))
 439                         flags |= IRQ_LEVEL;
 440                 /* note that IRQF_TRIGGER_MASK == IRQ_TYPE_SENSE_MASK */
 441                 desc->status &= ~(IRQ_LEVEL | IRQ_TYPE_SENSE_MASK);
 442                 desc->status |= flags;
 443         }
 444
 445         return ret;
 446 }
 447
 448 /*
 449  * Default primary interrupt handler for threaded interrupts. Is
 450  * assigned as primary handler when request_threaded_irq is called
 451  * with handler == NULL. Useful for oneshot interrupts.
 452  */
 453 static irqreturn_t irq_default_primary_handler(int irq, void *dev_id)
 454 {
 455         return IRQ_WAKE_THREAD;
 456 }
 457
 458 /*
 459  * Primary handler for nested threaded interrupts. Should never be
 460  * called.
 461  */
 462 static irqreturn_t irq_nested_primary_handler(int irq, void *dev_id)
 463 {
 464         WARN(1, "Primary handler called for nested irq %d\n", irq);
 465         return IRQ_NONE;
 466 }
 467
 468 static int irq_wait_for_interrupt(struct irqaction *action)
 469 {
 470         while (!kthread_should_stop()) {
 471                 set_current_state(TASK_INTERRUPTIBLE);
 472
 473                 if (test_and_clear_bit(IRQTF_RUNTHREAD,
 474                                        &action->thread_flags)) {
 475                         __set_current_state(TASK_RUNNING);
 476                         return 0;
 477                 }
 478                 schedule();
 479         }
 480         return -1;
 481 }
 482
 483 /*
 484  * Oneshot interrupts keep the irq line masked until the threaded
 485  * handler finished. unmask if the interrupt has not been disabled and
 486  * is marked MASKED.
 487  */
 488 static void irq_finalize_oneshot(unsigned int irq, struct irq_desc *desc)
 489 {
 490 again:
 491         chip_bus_lock(irq, desc);
 492         raw_spin_lock_irq(&desc->lock);
 493
 494         /*
 495          * Implausible though it may be we need to protect us against
 496          * the following scenario:
 497          *
 498          * The thread is faster done than the hard interrupt handler
 499          * on the other CPU. If we unmask the irq line then the
 500          * interrupt can come in again and masks the line, leaves due
 501          * to IRQ_INPROGRESS and the irq line is masked forever.
 502          */
 503         if (unlikely(desc->status & IRQ_INPROGRESS)) {
 504                 raw_spin_unlock_irq(&desc->lock);
 505                 chip_bus_sync_unlock(irq, desc);
 506                 cpu_relax();
 507                 goto again;
 508         }
 509
 510         if (!(desc->status & IRQ_DISABLED) && (desc->status & IRQ_MASKED)) {
 511                 desc->status &= ~IRQ_MASKED;
 512                 desc->chip->unmask(irq);
 513         }
 514         raw_spin_unlock_irq(&desc->lock);
 515         chip_bus_sync_unlock(irq, desc);
 516 }
 517
 518 #ifdef CONFIG_SMP
 519 /*
 520  * Check whether we need to change the affinity of the interrupt thread.
 521  */
 522 static void
 523 irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action)
 524 {
 525         cpumask_var_t mask;
 526
 527         if (!test_and_clear_bit(IRQTF_AFFINITY, &action->thread_flags))
 528                 return;
 529
 530         /*
 531          * In case we are out of memory we set IRQTF_AFFINITY again and
 532          * try again next time
 533          */
 534         if (!alloc_cpumask_var(&mask, GFP_KERNEL)) {
 535                 set_bit(IRQTF_AFFINITY, &action->thread_flags);
 536                 return;
 537         }
 538
 539         raw_spin_lock_irq(&desc->lock);
 540         cpumask_copy(mask, desc->affinity);
 541         raw_spin_unlock_irq(&desc->lock);
 542
 543         set_cpus_allowed_ptr(current, mask);
 544         free_cpumask_var(mask);
 545 }
 546 #else
 547 static inline void
 548 irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action) { }
 549 #endif
 550
 551 /*
 552  * Interrupt handler thread
 553  */
 554 static int irq_thread(void *data)
 555 {
 556         struct sched_param param = { .sched_priority = MAX_USER_RT_PRIO/2, };
 557         struct irqaction *action = data;
 558         struct irq_desc *desc = irq_to_desc(action->irq);
 559         int wake, oneshot = desc->status & IRQ_ONESHOT;
 560
 561         sched_setscheduler(current, SCHED_FIFO, &param);
 562         current->irqaction = action;
 563
 564         while (!irq_wait_for_interrupt(action)) {
 565
 566                 irq_thread_check_affinity(desc, action);
 567
 568                 atomic_inc(&desc->threads_active);
 569
 570                 raw_spin_lock_irq(&desc->lock);
 571                 if (unlikely(desc->status & IRQ_DISABLED)) {
 572                         /*
 573                          * CHECKME: We might need a dedicated
 574                          * IRQ_THREAD_PENDING flag here, which
 575                          * retriggers the thread in check_irq_resend()
 576                          * but AFAICT IRQ_PENDING should be fine as it
 577                          * retriggers the interrupt itself --- tglx
 578                          */
 579                         desc->status |= IRQ_PENDING;
 580                         raw_spin_unlock_irq(&desc->lock);
 581                 } else {
 582                         raw_spin_unlock_irq(&desc->lock);
 583
 584                         action->thread_fn(action->irq, action->dev_id);
 585
 586                         if (oneshot)
 587                                 irq_finalize_oneshot(action->irq, desc);
 588                 }
 589
 590                 wake = atomic_dec_and_test(&desc->threads_active);
 591
 592                 if (wake && waitqueue_active(&desc->wait_for_threads))
 593                         wake_up(&desc->wait_for_threads);
 594         }
 595
 596         /*
 597          * Clear irqaction. Otherwise exit_irq_thread() would make
 598          * fuzz about an active irq thread going into nirvana.
 599          */
 600         current->irqaction = NULL;
 601         return 0;
 602 }
 603
 604 /*
 605  * Called from do_exit()
 606  */
 607 void exit_irq_thread(void)
 608 {
 609         struct task_struct *tsk = current;
 610
 611         if (!tsk->irqaction)
 612                 return;
 613
 614         printk(KERN_ERR
 615                "exiting task \"%s\" (%d) is an active IRQ thread (irq %d)\n",
 616                tsk->comm ? tsk->comm : "", tsk->pid, tsk->irqaction->irq);
 617
 618         /*
 619          * Set the THREAD DIED flag to prevent further wakeups of the
 620          * soon to be gone threaded handler.
 621          */
 622         set_bit(IRQTF_DIED, &tsk->irqaction->flags);
 623 }
 624
 625 /*
 626  * Internal function to register an irqaction - typically used to
 627  * allocate special interrupts that are part of the architecture.
 628  */
 629 static int
 630 __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
 631 {
 632         struct irqaction *old, **old_ptr;
 633         const char *old_name = NULL;
 634         unsigned long flags;
 635         int nested, shared = 0;
 636         int ret;
 637
 638         if (!desc)
 639                 return -EINVAL;
 640
 641         if (desc->chip == &no_irq_chip)
 642                 return -ENOSYS;
 643         /*
 644          * Some drivers like serial.c use request_irq() heavily,
 645          * so we have to be careful not to interfere with a
 646          * running system.
 647          */
 648         if (new->flags & IRQF_SAMPLE_RANDOM) {
 649                 /*
 650                  * This function might sleep, we want to call it first,
 651                  * outside of the atomic block.
 652                  * Yes, this might clear the entropy pool if the wrong
 653                  * driver is attempted to be loaded, without actually
 654                  * installing a new handler, but is this really a problem,
 655                  * only the sysadmin is able to do this.
 656                  */
 657                 rand_initialize_irq(irq);
 658         }
 659
 660         /* Oneshot interrupts are not allowed with shared */
 661         if ((new->flags & IRQF_ONESHOT) && (new->flags & IRQF_SHARED))
 662                 return -EINVAL;
 663
 664         /*
 665          * Check whether the interrupt nests into another interrupt
 666          * thread.
 667          */
 668         nested = desc->status & IRQ_NESTED_THREAD;
 669         if (nested) {
 670                 if (!new->thread_fn)
 671                         return -EINVAL;
 672                 /*
 673                  * Replace the primary handler which was provided from
 674                  * the driver for non nested interrupt handling by the
 675                  * dummy function which warns when called.
 676                  */
 677                 new->handler = irq_nested_primary_handler;
 678         }
 679
 680         /*
 681          * Create a handler thread when a thread function is supplied
 682          * and the interrupt does not nest into another interrupt
 683          * thread.
 684          */
 685         if (new->thread_fn && !nested) {
 686                 struct task_struct *t;
 687
 688                 t = kthread_create(irq_thread, new, "irq/%d-%s", irq,
 689                                    new->name);
 690                 if (IS_ERR(t))
 691                         return PTR_ERR(t);
 692                 /*
 693                  * We keep the reference to the task struct even if
 694                  * the thread dies to avoid that the interrupt code
 695                  * references an already freed task_struct.
 696                  */
 697                 get_task_struct(t);
 698                 new->thread = t;
 699         }
 700
 701         /*
 702          * The following block of code has to be executed atomically
 703          */
 704         raw_spin_lock_irqsave(&desc->lock, flags);
 705         old_ptr = &desc->action;
 706         old = *old_ptr;
 707         if (old) {
 708                 /*
 709                  * Can't share interrupts unless both agree to and are
 710                  * the same type (level, edge, polarity). So both flag
 711                  * fields must have IRQF_SHARED set and the bits which
 712                  * set the trigger type must match.
 713                  */
 714                 if (!((old->flags & new->flags) & IRQF_SHARED) ||
 715                     ((old->flags ^ new->flags) & IRQF_TRIGGER_MASK)) {
 716                         old_name = old->name;
 717                         goto mismatch;
 718                 }
 719
 720 #if defined(CONFIG_IRQ_PER_CPU)
 721                 /* All handlers must agree on per-cpuness */
 722                 if ((old->flags & IRQF_PERCPU) !=
 723                     (new->flags & IRQF_PERCPU))
 724                         goto mismatch;
 725 #endif
 726
 727                 /* add new interrupt at end of irq queue */
 728                 do {
 729                         old_ptr = &old->next;
 730                         old = *old_ptr;
 731                 } while (old);
 732                 shared = 1;
 733         }
 734
 735         if (!shared) {
 736                 irq_chip_set_defaults(desc->chip);
 737
 738                 init_waitqueue_head(&desc->wait_for_threads);
 739
 740                 /* Setup the type (level, edge polarity) if configured: */
 741                 if (new->flags & IRQF_TRIGGER_MASK) {
 742                         ret = __irq_set_trigger(desc, irq,
 743                                         new->flags & IRQF_TRIGGER_MASK);
 744
 745                         if (ret)
 746                                 goto out_thread;
 747                 } else
 748                         compat_irq_chip_set_default_handler(desc);
 749 #if defined(CONFIG_IRQ_PER_CPU)
 750                 if (new->flags & IRQF_PERCPU)
 751                         desc->status |= IRQ_PER_CPU;
 752 #endif
 753
 754                 desc->status &= ~(IRQ_AUTODETECT | IRQ_WAITING | IRQ_ONESHOT |
 755                                   IRQ_INPROGRESS | IRQ_SPURIOUS_DISABLED);
 756
 757                 if (new->flags & IRQF_ONESHOT)
 758                         desc->status |= IRQ_ONESHOT;
 759
 760                 /*
 761                  * Force MSI interrupts to run with interrupts
 762                  * disabled. The multi vector cards can cause stack
 763                  * overflows due to nested interrupts when enough of
 764                  * them are directed to a core and fire at the same
 765                  * time.
 766                  */
 767                 if (desc->msi_desc)
 768                         new->flags |= IRQF_DISABLED;
 769
 770                 if (!(desc->status & IRQ_NOAUTOEN)) {
 771                         desc->depth = 0;
 772                         desc->status &= ~IRQ_DISABLED;
 773                         desc->chip->startup(irq);
 774                 } else
 775                         /* Undo nested disables: */
 776                         desc->depth = 1;
 777
 778                 /* Exclude IRQ from balancing if requested */
 779                 if (new->flags & IRQF_NOBALANCING)
 780                         desc->status |= IRQ_NO_BALANCING;
 781
 782                 /* Set default affinity mask once everything is setup */
 783                 setup_affinity(irq, desc);
 784
 785         } else if ((new->flags & IRQF_TRIGGER_MASK)
 786                         && (new->flags & IRQF_TRIGGER_MASK)
 787                                 != (desc->status & IRQ_TYPE_SENSE_MASK)) {
 788                 /* hope the handler works with the actual trigger mode... */
 789                 pr_warning("IRQ %d uses trigger mode %d; requested %d\n",
 790                                 irq, (int)(desc->status & IRQ_TYPE_SENSE_MASK),
 791                                 (int)(new->flags & IRQF_TRIGGER_MASK));
 792         }
 793
 794         new->irq = irq;
 795         *old_ptr = new;
 796
 797         /* Reset broken irq detection when installing new handler */
 798         desc->irq_count = 0;
 799         desc->irqs_unhandled = 0;
 800
 801         /*
 802          * Check whether we disabled the irq via the spurious handler
 803          * before. Reenable it and give it another chance.
 804          */
 805         if (shared && (desc->status & IRQ_SPURIOUS_DISABLED)) {
 806                 desc->status &= ~IRQ_SPURIOUS_DISABLED;
 807                 __enable_irq(desc, irq, false);
 808         }
 809
 810         raw_spin_unlock_irqrestore(&desc->lock, flags);
 811
 812         /*
 813          * Strictly no need to wake it up, but hung_task complains
 814          * when no hard interrupt wakes the thread up.
 815          */
 816         if (new->thread)
 817                 wake_up_process(new->thread);
 818
 819         register_irq_proc(irq, desc);
 820         new->dir = NULL;
 821         register_handler_proc(irq, new);
 822
 823         return 0;
 824
 825 mismatch:
 826 #ifdef CONFIG_DEBUG_SHIRQ
 827         if (!(new->flags & IRQF_PROBE_SHARED)) {
 828                 printk(KERN_ERR "IRQ handler type mismatch for IRQ %d\n", irq);
 829                 if (old_name)
 830                         printk(KERN_ERR "current handler: %s\n", old_name);
 831                 dump_stack();
 832         }
 833 #endif
 834         ret = -EBUSY;
 835
 836 out_thread:
 837         raw_spin_unlock_irqrestore(&desc->lock, flags);
 838         if (new->thread) {
 839                 struct task_struct *t = new->thread;
 840
 841                 new->thread = NULL;
 842                 if (likely(!test_bit(IRQTF_DIED, &new->thread_flags)))
 843                         kthread_stop(t);
 844                 put_task_struct(t);
 845         }
 846         return ret;
 847 }
 848
 849 /**
 850  *      setup_irq - setup an interrupt
 851  *      @irq: Interrupt line to setup
 852  *      @act: irqaction for the interrupt
 853  *
 854  * Used to statically setup interrupts in the early boot process.
 855  */
 856 int setup_irq(unsigned int irq, struct irqaction *act)
 857 {
 858         struct irq_desc *desc = irq_to_desc(irq);
 859
 860         return __setup_irq(irq, desc, act);
 861 }
 862 EXPORT_SYMBOL_GPL(setup_irq);
 863
 864  /*
 865  * Internal function to unregister an irqaction - used to free
 866  * regular and special interrupts that are part of the architecture.
 867  */
 868 static struct irqaction *__free_irq(unsigned int irq, void *dev_id)
 869 {
 870         struct irq_desc *desc = irq_to_desc(irq);
 871         struct irqaction *action, **action_ptr;
 872         unsigned long flags;
 873
 874         WARN(in_interrupt(), "Trying to free IRQ %d from IRQ context!\n", irq);
 875
 876         if (!desc)
 877                 return NULL;
 878
 879         raw_spin_lock_irqsave(&desc->lock, flags);
 880
 881         /*
 882          * There can be multiple actions per IRQ descriptor, find the right
 883          * one based on the dev_id:
 884          */
 885         action_ptr = &desc->action;
 886         for (;;) {
 887                 action = *action_ptr;
 888
 889                 if (!action) {
 890                         WARN(1, "Trying to free already-free IRQ %d\n", irq);
 891                         raw_spin_unlock_irqrestore(&desc->lock, flags);
 892
 893                         return NULL;
 894                 }
 895
 896                 if (action->dev_id == dev_id)
 897                         break;
 898                 action_ptr = &action->next;
 899         }
 900
 901         /* Found it - now remove it from the list of entries: */
 902         *action_ptr = action->next;
 903
 904         /* Currently used only by UML, might disappear one day: */
 905 #ifdef CONFIG_IRQ_RELEASE_METHOD
 906         if (desc->chip->release)
 907                 desc->chip->release(irq, dev_id);
 908 #endif
 909
 910         /* If this was the last handler, shut down the IRQ line: */
 911         if (!desc->action) {
 912                 desc->status |= IRQ_DISABLED;
 913                 if (desc->chip->shutdown)
 914                         desc->chip->shutdown(irq);
 915                 else
 916                         desc->chip->disable(irq);
 917         }
 918
 919         raw_spin_unlock_irqrestore(&desc->lock, flags);
 920
 921         unregister_handler_proc(irq, action);
 922
 923         /* Make sure it's not being used on another CPU: */
 924         synchronize_irq(irq);
 925
 926 #ifdef CONFIG_DEBUG_SHIRQ
 927         /*
 928          * It's a shared IRQ -- the driver ought to be prepared for an IRQ
 929          * event to happen even now it's being freed, so let's make sure that
 930          * is so by doing an extra call to the handler ....
 931          *
 932          * ( We do this after actually deregistering it, to make sure that a
 933          *   'real' IRQ doesn't run in * parallel with our fake. )
 934          */
 935         if (action->flags & IRQF_SHARED) {
 936                 local_irq_save(flags);
 937                 action->handler(irq, dev_id);
 938                 local_irq_restore(flags);
 939         }
 940 #endif
 941
 942         if (action->thread) {
 943                 if (!test_bit(IRQTF_DIED, &action->thread_flags))
 944                         kthread_stop(action->thread);
 945                 put_task_struct(action->thread);
 946         }
 947
 948         return action;
 949 }
 950
 951 /**
 952  *      remove_irq - free an interrupt
 953  *      @irq: Interrupt line to free
 954  *      @act: irqaction for the interrupt
 955  *
 956  * Used to remove interrupts statically setup by the early boot process.
 957  */
 958 void remove_irq(unsigned int irq, struct irqaction *act)
 959 {
 960         __free_irq(irq, act->dev_id);
 961 }
 962 EXPORT_SYMBOL_GPL(remove_irq);
 963
 964 /**
 965  *      free_irq - free an interrupt allocated with request_irq
 966  *      @irq: Interrupt line to free
 967  *      @dev_id: Device identity to free
 968  *
 969  *      Remove an interrupt handler. The handler is removed and if the
 970  *      interrupt line is no longer in use by any driver it is disabled.
 971  *      On a shared IRQ the caller must ensure the interrupt is disabled
 972  *      on the card it drives before calling this function. The function
 973  *      does not return until any executing interrupts for this IRQ
 974  *      have completed.
 975  *
 976  *      This function must not be called from interrupt context.
 977  */
 978 void free_irq(unsigned int irq, void *dev_id)
 979 {
 980         struct irq_desc *desc = irq_to_desc(irq);
 981
 982         if (!desc)
 983                 return;
 984
 985         chip_bus_lock(irq, desc);
 986         kfree(__free_irq(irq, dev_id));
 987         chip_bus_sync_unlock(irq, desc);
 988 }
 989 EXPORT_SYMBOL(free_irq);
 990
 991 /**
 992  *      request_threaded_irq - allocate an interrupt line
 993  *      @irq: Interrupt line to allocate
 994  *      @handler: Function to be called when the IRQ occurs.
 995  *                Primary handler for threaded interrupts
 996  *                If NULL and thread_fn != NULL the default
 997  *                primary handler is installed
 998  *      @thread_fn: Function called from the irq handler thread
 999  *                  If NULL, no irq thread is created
1000  *      @irqflags: Interrupt type flags
1001  *      @devname: An ascii name for the claiming device
1002  *      @dev_id: A cookie passed back to the handler function
1003  *
1004  *      This call allocates interrupt resources and enables the
1005  *      interrupt line and IRQ handling. From the point this
1006  *      call is made your handler function may be invoked. Since
1007  *      your handler function must clear any interrupt the board
1008  *      raises, you must take care both to initialise your hardware
1009  *      and to set up the interrupt handler in the right order.
1010  *
1011  *      If you want to set up a threaded irq handler for your device
1012  *      then you need to supply @handler and @thread_fn. @handler ist
1013  *      still called in hard interrupt context and has to check
1014  *      whether the interrupt originates from the device. If yes it
1015  *      needs to disable the interrupt on the device and return
1016  *      IRQ_WAKE_THREAD which will wake up the handler thread and run
1017  *      @thread_fn. This split handler design is necessary to support
1018  *      shared interrupts.
1019  *
1020  *      Dev_id must be globally unique. Normally the address of the
1021  *      device data structure is used as the cookie. Since the handler
1022  *      receives this value it makes sense to use it.
1023  *
1024  *      If your interrupt is shared you must pass a non NULL dev_id
1025  *      as this is required when freeing the interrupt.
1026  *
1027  *      Flags:
1028  *
1029  *      IRQF_SHARED             Interrupt is shared
1030  *      IRQF_DISABLED   Disable local interrupts while processing
1031  *      IRQF_SAMPLE_RANDOM      The interrupt can be used for entropy
1032  *      IRQF_TRIGGER_*          Specify active edge(s) or level
1033  *
1034  */
1035 int request_threaded_irq(unsigned int irq, irq_handler_t handler,
1036                          irq_handler_t thread_fn, unsigned long irqflags,
1037                          const char *devname, void *dev_id)
1038 {
1039         struct irqaction *action;
1040         struct irq_desc *desc;
1041         int retval;
1042
1043         /*
1044          * handle_IRQ_event() always ignores IRQF_DISABLED except for
1045          * the _first_ irqaction (sigh).  That can cause oopsing, but
1046          * the behavior is classified as "will not fix" so we need to
1047          * start nudging drivers away from using that idiom.
1048          */
1049         if ((irqflags & (IRQF_SHARED|IRQF_DISABLED)) ==
1050                                         (IRQF_SHARED|IRQF_DISABLED)) {
1051                 pr_warning(
1052                   "IRQ %d/%s: IRQF_DISABLED is not guaranteed on shared IRQs\n",
1053                         irq, devname);
1054         }
1055
1056 #ifdef CONFIG_LOCKDEP
1057         /*
1058          * Lockdep wants atomic interrupt handlers:
1059          */
1060         irqflags |= IRQF_DISABLED;
1061 #endif
1062         /*
1063          * Sanity-check: shared interrupts must pass in a real dev-ID,
1064          * otherwise we'll have trouble later trying to figure out
1065          * which interrupt is which (messes up the interrupt freeing
1066          * logic etc).
1067          */
1068         if ((irqflags & IRQF_SHARED) && !dev_id)
1069                 return -EINVAL;
1070
1071         desc = irq_to_desc(irq);
1072         if (!desc)
1073                 return -EINVAL;
1074
1075         if (desc->status & IRQ_NOREQUEST)
1076                 return -EINVAL;
1077
1078         if (!handler) {
1079                 if (!thread_fn)
1080                         return -EINVAL;
1081                 handler = irq_default_primary_handler;
1082         }
1083
1084         action = kzalloc(sizeof(struct irqaction), GFP_KERNEL);
1085         if (!action)
1086                 return -ENOMEM;
1087
1088         action->handler = handler;
1089         action->thread_fn = thread_fn;
1090         action->flags = irqflags;
1091         action->name = devname;
1092         action->dev_id = dev_id;
1093
1094         chip_bus_lock(irq, desc);
1095         retval = __setup_irq(irq, desc, action);
1096         chip_bus_sync_unlock(irq, desc);
1097
1098         if (retval)
1099                 kfree(action);
1100
1101 #ifdef CONFIG_DEBUG_SHIRQ
1102         if (!retval && (irqflags & IRQF_SHARED)) {
1103                 /*
1104                  * It's a shared IRQ -- the driver ought to be prepared for it
1105                  * to happen immediately, so let's make sure....
1106                  * We disable the irq to make sure that a 'real' IRQ doesn't
1107                  * run in parallel with our fake.
1108                  */
1109                 unsigned long flags;
1110
1111                 disable_irq(irq);
1112                 local_irq_save(flags);
1113
1114                 handler(irq, dev_id);
1115
1116                 local_irq_restore(flags);
1117                 enable_irq(irq);
1118         }
1119 #endif
1120         return retval;
1121 }
1122 EXPORT_SYMBOL(request_threaded_irq);