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