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 void
  84 irq_set_thread_affinity(struct irq_desc *desc, const struct cpumask *cpumask)
  85 {
  86         struct irqaction *action = desc->action;
  87
  88         while (action) {
  89                 if (action->thread)
  90                         set_cpus_allowed_ptr(action->thread, cpumask);
  91                 action = action->next;
  92         }
  93 }
  94
  95 /**
  96  *      irq_set_affinity - Set the irq affinity of a given irq
  97  *      @irq:           Interrupt to set affinity
  98  *      @cpumask:       cpumask
  99  *
 100  */
 101 int irq_set_affinity(unsigned int irq, const struct cpumask *cpumask)
 102 {
 103         struct irq_desc *desc = irq_to_desc(irq);
 104         unsigned long flags;
 105
 106         if (!desc->chip->set_affinity)
 107                 return -EINVAL;
 108
 109         spin_lock_irqsave(&desc->lock, flags);
 110
 111 #ifdef CONFIG_GENERIC_PENDING_IRQ
 112         if (desc->status & IRQ_MOVE_PCNTXT) {
 113                 if (!desc->chip->set_affinity(irq, cpumask)) {
 114                         cpumask_copy(desc->affinity, cpumask);
 115                         irq_set_thread_affinity(desc, cpumask);
 116                 }
 117         }
 118         else {
 119                 desc->status |= IRQ_MOVE_PENDING;
 120                 cpumask_copy(desc->pending_mask, cpumask);
 121         }
 122 #else
 123         if (!desc->chip->set_affinity(irq, cpumask)) {
 124                 cpumask_copy(desc->affinity, cpumask);
 125                 irq_set_thread_affinity(desc, cpumask);
 126         }
 127 #endif
 128         desc->status |= IRQ_AFFINITY_SET;
 129         spin_unlock_irqrestore(&desc->lock, flags);
 130         return 0;
 131 }
 132
 133 #ifndef CONFIG_AUTO_IRQ_AFFINITY
 134 /*
 135  * Generic version of the affinity autoselector.
 136  */
 137 static int setup_affinity(unsigned int irq, struct irq_desc *desc)
 138 {
 139         if (!irq_can_set_affinity(irq))
 140                 return 0;
 141
 142         /*
 143          * Preserve an userspace affinity setup, but make sure that
 144          * one of the targets is online.
 145          */
 146         if (desc->status & (IRQ_AFFINITY_SET | IRQ_NO_BALANCING)) {
 147                 if (cpumask_any_and(desc->affinity, cpu_online_mask)
 148                     < nr_cpu_ids)
 149                         goto set_affinity;
 150                 else
 151                         desc->status &= ~IRQ_AFFINITY_SET;
 152         }
 153
 154         cpumask_and(desc->affinity, cpu_online_mask, irq_default_affinity);
 155 set_affinity:
 156         desc->chip->set_affinity(irq, desc->affinity);
 157
 158         return 0;
 159 }
 160 #else
 161 static inline int setup_affinity(unsigned int irq, struct irq_desc *d)
 162 {
 163         return irq_select_affinity(irq);
 164 }
 165 #endif
 166
 167 /*
 168  * Called when affinity is set via /proc/irq
 169  */
 170 int irq_select_affinity_usr(unsigned int irq)
 171 {
 172         struct irq_desc *desc = irq_to_desc(irq);
 173         unsigned long flags;
 174         int ret;
 175
 176         spin_lock_irqsave(&desc->lock, flags);
 177         ret = setup_affinity(irq, desc);
 178         if (!ret)
 179                 irq_set_thread_affinity(desc, desc->affinity);
 180         spin_unlock_irqrestore(&desc->lock, flags);
 181
 182         return ret;
 183 }
 184
 185 #else
 186 static inline int setup_affinity(unsigned int irq, struct irq_desc *desc)
 187 {
 188         return 0;
 189 }
 190 #endif
 191
 192 void __disable_irq(struct irq_desc *desc, unsigned int irq, bool suspend)
 193 {
 194         if (suspend) {
 195                 if (!desc->action || (desc->action->flags & IRQF_TIMER))
 196                         return;
 197                 desc->status |= IRQ_SUSPENDED;
 198         }
 199
 200         if (!desc->depth++) {
 201                 desc->status |= IRQ_DISABLED;
 202                 desc->chip->disable(irq);
 203         }
 204 }
 205
 206 /**
 207  *      disable_irq_nosync - disable an irq without waiting
 208  *      @irq: Interrupt to disable
 209  *
 210  *      Disable the selected interrupt line.  Disables and Enables are
 211  *      nested.
 212  *      Unlike disable_irq(), this function does not ensure existing
 213  *      instances of the IRQ handler have completed before returning.
 214  *
 215  *      This function may be called from IRQ context.
 216  */
 217 void disable_irq_nosync(unsigned int irq)
 218 {
 219         struct irq_desc *desc = irq_to_desc(irq);
 220         unsigned long flags;
 221
 222         if (!desc)
 223                 return;
 224
 225         spin_lock_irqsave(&desc->lock, flags);
 226         __disable_irq(desc, irq, false);
 227         spin_unlock_irqrestore(&desc->lock, flags);
 228 }
 229 EXPORT_SYMBOL(disable_irq_nosync);
 230
 231 /**
 232  *      disable_irq - disable an irq and wait for completion
 233  *      @irq: Interrupt to disable
 234  *
 235  *      Disable the selected interrupt line.  Enables and Disables are
 236  *      nested.
 237  *      This function waits for any pending IRQ handlers for this interrupt
 238  *      to complete before returning. If you use this function while
 239  *      holding a resource the IRQ handler may need you will deadlock.
 240  *
 241  *      This function may be called - with care - from IRQ context.
 242  */
 243 void disable_irq(unsigned int irq)
 244 {
 245         struct irq_desc *desc = irq_to_desc(irq);
 246
 247         if (!desc)
 248                 return;
 249
 250         disable_irq_nosync(irq);
 251         if (desc->action)
 252                 synchronize_irq(irq);
 253 }
 254 EXPORT_SYMBOL(disable_irq);
 255
 256 void __enable_irq(struct irq_desc *desc, unsigned int irq, bool resume)
 257 {
 258         if (resume)
 259                 desc->status &= ~IRQ_SUSPENDED;
 260
 261         switch (desc->depth) {
 262         case 0:
 263  err_out:
 264                 WARN(1, KERN_WARNING "Unbalanced enable for IRQ %d\n", irq);
 265                 break;
 266         case 1: {
 267                 unsigned int status = desc->status & ~IRQ_DISABLED;
 268
 269                 if (desc->status & IRQ_SUSPENDED)
 270                         goto err_out;
 271                 /* Prevent probing on this irq: */
 272                 desc->status = status | IRQ_NOPROBE;
 273                 check_irq_resend(desc, irq);
 274                 /* fall-through */
 275         }
 276         default:
 277                 desc->depth--;
 278         }
 279 }
 280
 281 /**
 282  *      enable_irq - enable handling of an irq
 283  *      @irq: Interrupt to enable
 284  *
 285  *      Undoes the effect of one call to disable_irq().  If this
 286  *      matches the last disable, processing of interrupts on this
 287  *      IRQ line is re-enabled.
 288  *
 289  *      This function may be called from IRQ context.
 290  */
 291 void enable_irq(unsigned int irq)
 292 {
 293         struct irq_desc *desc = irq_to_desc(irq);
 294         unsigned long flags;
 295
 296         if (!desc)
 297                 return;
 298
 299         spin_lock_irqsave(&desc->lock, flags);
 300         __enable_irq(desc, irq, false);
 301         spin_unlock_irqrestore(&desc->lock, flags);
 302 }
 303 EXPORT_SYMBOL(enable_irq);
 304
 305 static int set_irq_wake_real(unsigned int irq, unsigned int on)
 306 {
 307         struct irq_desc *desc = irq_to_desc(irq);
 308         int ret = -ENXIO;
 309
 310         if (desc->chip->set_wake)
 311                 ret = desc->chip->set_wake(irq, on);
 312
 313         return ret;
 314 }
 315
 316 /**
 317  *      set_irq_wake - control irq power management wakeup
 318  *      @irq:   interrupt to control
 319  *      @on:    enable/disable power management wakeup
 320  *
 321  *      Enable/disable power management wakeup mode, which is
 322  *      disabled by default.  Enables and disables must match,
 323  *      just as they match for non-wakeup mode support.
 324  *
 325  *      Wakeup mode lets this IRQ wake the system from sleep
 326  *      states like "suspend to RAM".
 327  */
 328 int set_irq_wake(unsigned int irq, unsigned int on)
 329 {
 330         struct irq_desc *desc = irq_to_desc(irq);
 331         unsigned long flags;
 332         int ret = 0;
 333
 334         /* wakeup-capable irqs can be shared between drivers that
 335          * don't need to have the same sleep mode behaviors.
 336          */
 337         spin_lock_irqsave(&desc->lock, flags);
 338         if (on) {
 339                 if (desc->wake_depth++ == 0) {
 340                         ret = set_irq_wake_real(irq, on);
 341                         if (ret)
 342                                 desc->wake_depth = 0;
 343                         else
 344                                 desc->status |= IRQ_WAKEUP;
 345                 }
 346         } else {
 347                 if (desc->wake_depth == 0) {
 348                         WARN(1, "Unbalanced IRQ %d wake disable\n", irq);
 349                 } else if (--desc->wake_depth == 0) {
 350                         ret = set_irq_wake_real(irq, on);
 351                         if (ret)
 352                                 desc->wake_depth = 1;
 353                         else
 354                                 desc->status &= ~IRQ_WAKEUP;
 355                 }
 356         }
 357
 358         spin_unlock_irqrestore(&desc->lock, flags);
 359         return ret;
 360 }
 361 EXPORT_SYMBOL(set_irq_wake);
 362
 363 /*
 364  * Internal function that tells the architecture code whether a
 365  * particular irq has been exclusively allocated or is available
 366  * for driver use.
 367  */
 368 int can_request_irq(unsigned int irq, unsigned long irqflags)
 369 {
 370         struct irq_desc *desc = irq_to_desc(irq);
 371         struct irqaction *action;
 372
 373         if (!desc)
 374                 return 0;
 375
 376         if (desc->status & IRQ_NOREQUEST)
 377                 return 0;
 378
 379         action = desc->action;
 380         if (action)
 381                 if (irqflags & action->flags & IRQF_SHARED)
 382                         action = NULL;
 383
 384         return !action;
 385 }
 386
 387 void compat_irq_chip_set_default_handler(struct irq_desc *desc)
 388 {
 389         /*
 390          * If the architecture still has not overriden
 391          * the flow handler then zap the default. This
 392          * should catch incorrect flow-type setting.
 393          */
 394         if (desc->handle_irq == &handle_bad_irq)
 395                 desc->handle_irq = NULL;
 396 }
 397
 398 int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
 399                 unsigned long flags)
 400 {
 401         int ret;
 402         struct irq_chip *chip = desc->chip;
 403
 404         if (!chip || !chip->set_type) {
 405                 /*
 406                  * IRQF_TRIGGER_* but the PIC does not support multiple
 407                  * flow-types?
 408                  */
 409                 pr_debug("No set_type function for IRQ %d (%s)\n", irq,
 410                                 chip ? (chip->name ? : "unknown") : "unknown");
 411                 return 0;
 412         }
 413
 414         /* caller masked out all except trigger mode flags */
 415         ret = chip->set_type(irq, flags);
 416
 417         if (ret)
 418                 pr_err("setting trigger mode %d for irq %u failed (%pF)\n",
 419                                 (int)flags, irq, chip->set_type);
 420         else {
 421                 if (flags & (IRQ_TYPE_LEVEL_LOW | IRQ_TYPE_LEVEL_HIGH))
 422                         flags |= IRQ_LEVEL;
 423                 /* note that IRQF_TRIGGER_MASK == IRQ_TYPE_SENSE_MASK */
 424                 desc->status &= ~(IRQ_LEVEL | IRQ_TYPE_SENSE_MASK);
 425                 desc->status |= flags;
 426         }
 427
 428         return ret;
 429 }
 430
 431 static int irq_wait_for_interrupt(struct irqaction *action)
 432 {
 433         while (!kthread_should_stop()) {
 434                 set_current_state(TASK_INTERRUPTIBLE);
 435
 436                 if (test_and_clear_bit(IRQTF_RUNTHREAD,
 437                                        &action->thread_flags)) {
 438                         __set_current_state(TASK_RUNNING);
 439                         return 0;
 440                 }
 441                 schedule();
 442         }
 443         return -1;
 444 }
 445
 446 /*
 447  * Interrupt handler thread
 448  */
 449 static int irq_thread(void *data)
 450 {
 451         struct sched_param param = { .sched_priority = MAX_USER_RT_PRIO/2, };
 452         struct irqaction *action = data;
 453         struct irq_desc *desc = irq_to_desc(action->irq);
 454         int wake;
 455
 456         sched_setscheduler(current, SCHED_FIFO, &param);
 457         current->irqaction = action;
 458
 459         while (!irq_wait_for_interrupt(action)) {
 460
 461                 atomic_inc(&desc->threads_active);
 462
 463                 spin_lock_irq(&desc->lock);
 464                 if (unlikely(desc->status & IRQ_DISABLED)) {
 465                         /*
 466                          * CHECKME: We might need a dedicated
 467                          * IRQ_THREAD_PENDING flag here, which
 468                          * retriggers the thread in check_irq_resend()
 469                          * but AFAICT IRQ_PENDING should be fine as it
 470                          * retriggers the interrupt itself --- tglx
 471                          */
 472                         desc->status |= IRQ_PENDING;
 473                         spin_unlock_irq(&desc->lock);
 474                 } else {
 475                         spin_unlock_irq(&desc->lock);
 476
 477                         action->thread_fn(action->irq, action->dev_id);
 478                 }
 479
 480                 wake = atomic_dec_and_test(&desc->threads_active);
 481
 482                 if (wake && waitqueue_active(&desc->wait_for_threads))
 483                         wake_up(&desc->wait_for_threads);
 484         }
 485
 486         /*
 487          * Clear irqaction. Otherwise exit_irq_thread() would make
 488          * fuzz about an active irq thread going into nirvana.
 489          */
 490         current->irqaction = NULL;
 491         return 0;
 492 }
 493
 494 /*
 495  * Called from do_exit()
 496  */
 497 void exit_irq_thread(void)
 498 {
 499         struct task_struct *tsk = current;
 500
 501         if (!tsk->irqaction)
 502                 return;
 503
 504         printk(KERN_ERR
 505                "exiting task \"%s\" (%d) is an active IRQ thread (irq %d)\n",
 506                tsk->comm ? tsk->comm : "", tsk->pid, tsk->irqaction->irq);
 507
 508         /*
 509          * Set the THREAD DIED flag to prevent further wakeups of the
 510          * soon to be gone threaded handler.
 511          */
 512         set_bit(IRQTF_DIED, &tsk->irqaction->flags);
 513 }
 514
 515 /*
 516  * Internal function to register an irqaction - typically used to
 517  * allocate special interrupts that are part of the architecture.
 518  */
 519 static int
 520 __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
 521 {
 522         struct irqaction *old, **old_ptr;
 523         const char *old_name = NULL;
 524         unsigned long flags;
 525         int shared = 0;
 526         int ret;
 527
 528         if (!desc)
 529                 return -EINVAL;
 530
 531         if (desc->chip == &no_irq_chip)
 532                 return -ENOSYS;
 533         /*
 534          * Some drivers like serial.c use request_irq() heavily,
 535          * so we have to be careful not to interfere with a
 536          * running system.
 537          */
 538         if (new->flags & IRQF_SAMPLE_RANDOM) {
 539                 /*
 540                  * This function might sleep, we want to call it first,
 541                  * outside of the atomic block.
 542                  * Yes, this might clear the entropy pool if the wrong
 543                  * driver is attempted to be loaded, without actually
 544                  * installing a new handler, but is this really a problem,
 545                  * only the sysadmin is able to do this.
 546                  */
 547                 rand_initialize_irq(irq);
 548         }
 549
 550         /*
 551          * Threaded handler ?
 552          */
 553         if (new->thread_fn) {
 554                 struct task_struct *t;
 555
 556                 t = kthread_create(irq_thread, new, "irq/%d-%s", irq,
 557                                    new->name);
 558                 if (IS_ERR(t))
 559                         return PTR_ERR(t);
 560                 /*
 561                  * We keep the reference to the task struct even if
 562                  * the thread dies to avoid that the interrupt code
 563                  * references an already freed task_struct.
 564                  */
 565                 get_task_struct(t);
 566                 new->thread = t;
 567                 wake_up_process(t);
 568         }
 569
 570         /*
 571          * The following block of code has to be executed atomically
 572          */
 573         spin_lock_irqsave(&desc->lock, flags);
 574         old_ptr = &desc->action;
 575         old = *old_ptr;
 576         if (old) {
 577                 /*
 578                  * Can't share interrupts unless both agree to and are
 579                  * the same type (level, edge, polarity). So both flag
 580                  * fields must have IRQF_SHARED set and the bits which
 581                  * set the trigger type must match.
 582                  */
 583                 if (!((old->flags & new->flags) & IRQF_SHARED) ||
 584                     ((old->flags ^ new->flags) & IRQF_TRIGGER_MASK)) {
 585                         old_name = old->name;
 586                         goto mismatch;
 587                 }
 588
 589 #if defined(CONFIG_IRQ_PER_CPU)
 590                 /* All handlers must agree on per-cpuness */
 591                 if ((old->flags & IRQF_PERCPU) !=
 592                     (new->flags & IRQF_PERCPU))
 593                         goto mismatch;
 594 #endif
 595
 596                 /* add new interrupt at end of irq queue */
 597                 do {
 598                         old_ptr = &old->next;
 599                         old = *old_ptr;
 600                 } while (old);
 601                 shared = 1;
 602         }
 603
 604         if (!shared) {
 605                 irq_chip_set_defaults(desc->chip);
 606
 607                 init_waitqueue_head(&desc->wait_for_threads);
 608
 609                 /* Setup the type (level, edge polarity) if configured: */
 610                 if (new->flags & IRQF_TRIGGER_MASK) {
 611                         ret = __irq_set_trigger(desc, irq,
 612                                         new->flags & IRQF_TRIGGER_MASK);
 613
 614                         if (ret)
 615                                 goto out_thread;
 616                 } else
 617                         compat_irq_chip_set_default_handler(desc);
 618 #if defined(CONFIG_IRQ_PER_CPU)
 619                 if (new->flags & IRQF_PERCPU)
 620                         desc->status |= IRQ_PER_CPU;
 621 #endif
 622
 623                 desc->status &= ~(IRQ_AUTODETECT | IRQ_WAITING |
 624                                   IRQ_INPROGRESS | IRQ_SPURIOUS_DISABLED);
 625
 626                 if (!(desc->status & IRQ_NOAUTOEN)) {
 627                         desc->depth = 0;
 628                         desc->status &= ~IRQ_DISABLED;
 629                         desc->chip->startup(irq);
 630                 } else
 631                         /* Undo nested disables: */
 632                         desc->depth = 1;
 633
 634                 /* Exclude IRQ from balancing if requested */
 635                 if (new->flags & IRQF_NOBALANCING)
 636                         desc->status |= IRQ_NO_BALANCING;
 637
 638                 /* Set default affinity mask once everything is setup */
 639                 setup_affinity(irq, desc);
 640
 641         } else if ((new->flags & IRQF_TRIGGER_MASK)
 642                         && (new->flags & IRQF_TRIGGER_MASK)
 643                                 != (desc->status & IRQ_TYPE_SENSE_MASK)) {
 644                 /* hope the handler works with the actual trigger mode... */
 645                 pr_warning("IRQ %d uses trigger mode %d; requested %d\n",
 646                                 irq, (int)(desc->status & IRQ_TYPE_SENSE_MASK),
 647                                 (int)(new->flags & IRQF_TRIGGER_MASK));
 648         }
 649
 650         *old_ptr = new;
 651
 652         /* Reset broken irq detection when installing new handler */
 653         desc->irq_count = 0;
 654         desc->irqs_unhandled = 0;
 655
 656         /*
 657          * Check whether we disabled the irq via the spurious handler
 658          * before. Reenable it and give it another chance.
 659          */
 660         if (shared && (desc->status & IRQ_SPURIOUS_DISABLED)) {
 661                 desc->status &= ~IRQ_SPURIOUS_DISABLED;
 662                 __enable_irq(desc, irq, false);
 663         }
 664
 665         spin_unlock_irqrestore(&desc->lock, flags);
 666
 667         new->irq = irq;
 668         register_irq_proc(irq, desc);
 669         new->dir = NULL;
 670         register_handler_proc(irq, new);
 671
 672         return 0;
 673
 674 mismatch:
 675 #ifdef CONFIG_DEBUG_SHIRQ
 676         if (!(new->flags & IRQF_PROBE_SHARED)) {
 677                 printk(KERN_ERR "IRQ handler type mismatch for IRQ %d\n", irq);
 678                 if (old_name)
 679                         printk(KERN_ERR "current handler: %s\n", old_name);
 680                 dump_stack();
 681         }
 682 #endif
 683         ret = -EBUSY;
 684
 685 out_thread:
 686         spin_unlock_irqrestore(&desc->lock, flags);
 687         if (new->thread) {
 688                 struct task_struct *t = new->thread;
 689
 690                 new->thread = NULL;
 691                 if (likely(!test_bit(IRQTF_DIED, &new->thread_flags)))
 692                         kthread_stop(t);
 693                 put_task_struct(t);
 694         }
 695         return ret;
 696 }
 697
 698 /**
 699  *      setup_irq - setup an interrupt
 700  *      @irq: Interrupt line to setup
 701  *      @act: irqaction for the interrupt
 702  *
 703  * Used to statically setup interrupts in the early boot process.
 704  */
 705 int setup_irq(unsigned int irq, struct irqaction *act)
 706 {
 707         struct irq_desc *desc = irq_to_desc(irq);
 708
 709         return __setup_irq(irq, desc, act);
 710 }
 711 EXPORT_SYMBOL_GPL(setup_irq);
 712
 713  /*
 714  * Internal function to unregister an irqaction - used to free
 715  * regular and special interrupts that are part of the architecture.
 716  */
 717 static struct irqaction *__free_irq(unsigned int irq, void *dev_id)
 718 {
 719         struct irq_desc *desc = irq_to_desc(irq);
 720         struct irqaction *action, **action_ptr;
 721         struct task_struct *irqthread;
 722         unsigned long flags;
 723
 724         WARN(in_interrupt(), "Trying to free IRQ %d from IRQ context!\n", irq);
 725
 726         if (!desc)
 727                 return NULL;
 728
 729         spin_lock_irqsave(&desc->lock, flags);
 730
 731         /*
 732          * There can be multiple actions per IRQ descriptor, find the right
 733          * one based on the dev_id:
 734          */
 735         action_ptr = &desc->action;
 736         for (;;) {
 737                 action = *action_ptr;
 738
 739                 if (!action) {
 740                         WARN(1, "Trying to free already-free IRQ %d\n", irq);
 741                         spin_unlock_irqrestore(&desc->lock, flags);
 742
 743                         return NULL;
 744                 }
 745
 746                 if (action->dev_id == dev_id)
 747                         break;
 748                 action_ptr = &action->next;
 749         }
 750
 751         /* Found it - now remove it from the list of entries: */
 752         *action_ptr = action->next;
 753
 754         /* Currently used only by UML, might disappear one day: */
 755 #ifdef CONFIG_IRQ_RELEASE_METHOD
 756         if (desc->chip->release)
 757                 desc->chip->release(irq, dev_id);
 758 #endif
 759
 760         /* If this was the last handler, shut down the IRQ line: */
 761         if (!desc->action) {
 762                 desc->status |= IRQ_DISABLED;
 763                 if (desc->chip->shutdown)
 764                         desc->chip->shutdown(irq);
 765                 else
 766                         desc->chip->disable(irq);
 767         }
 768
 769         irqthread = action->thread;
 770         action->thread = NULL;
 771
 772         spin_unlock_irqrestore(&desc->lock, flags);
 773
 774         unregister_handler_proc(irq, action);
 775
 776         /* Make sure it's not being used on another CPU: */
 777         synchronize_irq(irq);
 778
 779         if (irqthread) {
 780                 if (!test_bit(IRQTF_DIED, &action->thread_flags))
 781                         kthread_stop(irqthread);
 782                 put_task_struct(irqthread);
 783         }
 784
 785 #ifdef CONFIG_DEBUG_SHIRQ
 786         /*
 787          * It's a shared IRQ -- the driver ought to be prepared for an IRQ
 788          * event to happen even now it's being freed, so let's make sure that
 789          * is so by doing an extra call to the handler ....
 790          *
 791          * ( We do this after actually deregistering it, to make sure that a
 792          *   'real' IRQ doesn't run in * parallel with our fake. )
 793          */
 794         if (action->flags & IRQF_SHARED) {
 795                 local_irq_save(flags);
 796                 action->handler(irq, dev_id);
 797                 local_irq_restore(flags);
 798         }
 799 #endif
 800         return action;
 801 }
 802
 803 /**
 804  *      remove_irq - free an interrupt
 805  *      @irq: Interrupt line to free
 806  *      @act: irqaction for the interrupt
 807  *
 808  * Used to remove interrupts statically setup by the early boot process.
 809  */
 810 void remove_irq(unsigned int irq, struct irqaction *act)
 811 {
 812         __free_irq(irq, act->dev_id);
 813 }
 814 EXPORT_SYMBOL_GPL(remove_irq);
 815
 816 /**
 817  *      free_irq - free an interrupt allocated with request_irq
 818  *      @irq: Interrupt line to free
 819  *      @dev_id: Device identity to free
 820  *
 821  *      Remove an interrupt handler. The handler is removed and if the
 822  *      interrupt line is no longer in use by any driver it is disabled.
 823  *      On a shared IRQ the caller must ensure the interrupt is disabled
 824  *      on the card it drives before calling this function. The function
 825  *      does not return until any executing interrupts for this IRQ
 826  *      have completed.
 827  *
 828  *      This function must not be called from interrupt context.
 829  */
 830 void free_irq(unsigned int irq, void *dev_id)
 831 {
 832         kfree(__free_irq(irq, dev_id));
 833 }
 834 EXPORT_SYMBOL(free_irq);
 835
 836 /**
 837  *      request_threaded_irq - allocate an interrupt line
 838  *      @irq: Interrupt line to allocate
 839  *      @handler: Function to be called when the IRQ occurs.
 840  *                Primary handler for threaded interrupts
 841  *      @thread_fn: Function called from the irq handler thread
 842  *                  If NULL, no irq thread is created
 843  *      @irqflags: Interrupt type flags
 844  *      @devname: An ascii name for the claiming device
 845  *      @dev_id: A cookie passed back to the handler function
 846  *
 847  *      This call allocates interrupt resources and enables the
 848  *      interrupt line and IRQ handling. From the point this
 849  *      call is made your handler function may be invoked. Since
 850  *      your handler function must clear any interrupt the board
 851  *      raises, you must take care both to initialise your hardware
 852  *      and to set up the interrupt handler in the right order.
 853  *
 854  *      If you want to set up a threaded irq handler for your device
 855  *      then you need to supply @handler and @thread_fn. @handler ist
 856  *      still called in hard interrupt context and has to check
 857  *      whether the interrupt originates from the device. If yes it
 858  *      needs to disable the interrupt on the device and return
 859  *      IRQ_THREAD_WAKE which will wake up the handler thread and run
 860  *      @thread_fn. This split handler design is necessary to support
 861  *      shared interrupts.
 862  *
 863  *      Dev_id must be globally unique. Normally the address of the
 864  *      device data structure is used as the cookie. Since the handler
 865  *      receives this value it makes sense to use it.
 866  *
 867  *      If your interrupt is shared you must pass a non NULL dev_id
 868  *      as this is required when freeing the interrupt.
 869  *
 870  *      Flags:
 871  *
 872  *      IRQF_SHARED             Interrupt is shared
 873  *      IRQF_DISABLED   Disable local interrupts while processing
 874  *      IRQF_SAMPLE_RANDOM      The interrupt can be used for entropy
 875  *      IRQF_TRIGGER_*          Specify active edge(s) or level
 876  *
 877  */
 878 int request_threaded_irq(unsigned int irq, irq_handler_t handler,
 879                          irq_handler_t thread_fn, unsigned long irqflags,
 880                          const char *devname, void *dev_id)
 881 {
 882         struct irqaction *action;
 883         struct irq_desc *desc;
 884         int retval;
 885
 886         /*
 887          * handle_IRQ_event() always ignores IRQF_DISABLED except for
 888          * the _first_ irqaction (sigh).  That can cause oopsing, but
 889          * the behavior is classified as "will not fix" so we need to
 890          * start nudging drivers away from using that idiom.
 891          */
 892         if ((irqflags & (IRQF_SHARED|IRQF_DISABLED)) ==
 893                                         (IRQF_SHARED|IRQF_DISABLED)) {
 894                 pr_warning(
 895                   "IRQ %d/%s: IRQF_DISABLED is not guaranteed on shared IRQs\n",
 896                         irq, devname);
 897         }
 898
 899 #ifdef CONFIG_LOCKDEP
 900         /*
 901          * Lockdep wants atomic interrupt handlers:
 902          */
 903         irqflags |= IRQF_DISABLED;
 904 #endif
 905         /*
 906          * Sanity-check: shared interrupts must pass in a real dev-ID,
 907          * otherwise we'll have trouble later trying to figure out
 908          * which interrupt is which (messes up the interrupt freeing
 909          * logic etc).
 910          */
 911         if ((irqflags & IRQF_SHARED) && !dev_id)
 912                 return -EINVAL;
 913
 914         desc = irq_to_desc(irq);
 915         if (!desc)
 916                 return -EINVAL;
 917
 918         if (desc->status & IRQ_NOREQUEST)
 919                 return -EINVAL;
 920         if (!handler)
 921                 return -EINVAL;
 922
 923         action = kzalloc(sizeof(struct irqaction), GFP_KERNEL);
 924         if (!action)
 925                 return -ENOMEM;
 926
 927         action->handler = handler;
 928         action->thread_fn = thread_fn;
 929         action->flags = irqflags;
 930         action->name = devname;
 931         action->dev_id = dev_id;
 932
 933         retval = __setup_irq(irq, desc, action);
 934         if (retval)
 935                 kfree(action);
 936
 937 #ifdef CONFIG_DEBUG_SHIRQ
 938         if (irqflags & IRQF_SHARED) {
 939                 /*
 940                  * It's a shared IRQ -- the driver ought to be prepared for it
 941                  * to happen immediately, so let's make sure....
 942                  * We disable the irq to make sure that a 'real' IRQ doesn't
 943                  * run in parallel with our fake.
 944                  */
 945                 unsigned long flags;
 946
 947                 disable_irq(irq);
 948                 local_irq_save(flags);
 949
 950                 handler(irq, dev_id);
 951
 952                 local_irq_restore(flags);
 953                 enable_irq(irq);
 954         }
 955 #endif
 956         return retval;
 957 }
 958 EXPORT_SYMBOL(request_threaded_irq);