kernel/irq/manage.c

   1 /*
   2  * linux/kernel/irq/manage.c
   3  *
   4  * Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
   5  * Copyright (C) 2005-2006 Thomas Gleixner
   6  *
   7  * This file contains driver APIs to the irq subsystem.
   8  */
   9
  10 #include <linux/irq.h>
  11 #include <linux/kthread.h>
  12 #include <linux/module.h>
  13 #include <linux/random.h>
  14 #include <linux/interrupt.h>
  15 #include <linux/slab.h>
  16 #include <linux/sched.h>
  17
  18 #include "internals.h"
  19
  20 /**
  21  *      synchronize_irq - wait for pending IRQ handlers (on other CPUs)
  22  *      @irq: interrupt number to wait for
  23  *
  24  *      This function waits for any pending IRQ handlers for this interrupt
  25  *      to complete before returning. If you use this function while
  26  *      holding a resource the IRQ handler may need you will deadlock.
  27  *
  28  *      This function may be called - with care - from IRQ context.
  29  */
  30 void synchronize_irq(unsigned int irq)
  31 {
  32         struct irq_desc *desc = irq_to_desc(irq);
  33         unsigned int status;
  34
  35         if (!desc)
  36                 return;
  37
  38         do {
  39                 unsigned long flags;
  40
  41                 /*
  42                  * Wait until we're out of the critical section.  This might
  43                  * give the wrong answer due to the lack of memory barriers.
  44                  */
  45                 while (desc->status & IRQ_INPROGRESS)
  46                         cpu_relax();
  47
  48                 /* Ok, that indicated we're done: double-check carefully. */
  49                 raw_spin_lock_irqsave(&desc->lock, flags);
  50                 status = desc->status;
  51                 raw_spin_unlock_irqrestore(&desc->lock, flags);
  52
  53                 /* Oops, that failed? */
  54         } while (status & IRQ_INPROGRESS);
  55
  56         /*
  57          * We made sure that no hardirq handler is running. Now verify
  58          * that no threaded handlers are active.
  59          */
  60         wait_event(desc->wait_for_threads, !atomic_read(&desc->threads_active));
  61 }
  62 EXPORT_SYMBOL(synchronize_irq);
  63
  64 #ifdef CONFIG_SMP
  65 cpumask_var_t irq_default_affinity;
  66
  67 /**
  68  *      irq_can_set_affinity - Check if the affinity of a given irq can be set
  69  *      @irq:           Interrupt to check
  70  *
  71  */
  72 int irq_can_set_affinity(unsigned int irq)
  73 {
  74         struct irq_desc *desc = irq_to_desc(irq);
  75
  76         if (CHECK_IRQ_PER_CPU(desc->status) || !desc->chip ||
  77             !desc->chip->set_affinity)
  78                 return 0;
  79
  80         return 1;
  81 }
  82
  83 /**
  84  *      irq_set_thread_affinity - Notify irq threads to adjust affinity
  85  *      @desc:          irq descriptor which has affitnity changed
  86  *
  87  *      We just set IRQTF_AFFINITY and delegate the affinity setting
  88  *      to the interrupt thread itself. We can not call
  89  *      set_cpus_allowed_ptr() here as we hold desc->lock and this
  90  *      code can be called from hard interrupt context.
  91  */
  92 void irq_set_thread_affinity(struct irq_desc *desc)
  93 {
  94         struct irqaction *action = desc->action;
  95
  96         while (action) {
  97                 if (action->thread)
  98                         set_bit(IRQTF_AFFINITY, &action->thread_flags);
  99                 action = action->next;
 100         }
 101 }
 102
 103 /**
 104  *      irq_set_affinity - Set the irq affinity of a given irq
 105  *      @irq:           Interrupt to set affinity
 106  *      @cpumask:       cpumask
 107  *
 108  */
 109 int irq_set_affinity(unsigned int irq, const struct cpumask *cpumask)
 110 {
 111         struct irq_desc *desc = irq_to_desc(irq);
 112         unsigned long flags;
 113
 114         if (!desc->chip->set_affinity)
 115                 return -EINVAL;
 116
 117         raw_spin_lock_irqsave(&desc->lock, flags);
 118
 119 #ifdef CONFIG_GENERIC_PENDING_IRQ
 120         if (desc->status & IRQ_MOVE_PCNTXT) {
 121                 if (!desc->chip->set_affinity(irq, cpumask)) {
 122                         cpumask_copy(desc->affinity, cpumask);
 123                         irq_set_thread_affinity(desc);
 124                 }
 125         }
 126         else {
 127                 desc->status |= IRQ_MOVE_PENDING;
 128                 cpumask_copy(desc->pending_mask, cpumask);
 129         }
 130 #else
 131         if (!desc->chip->set_affinity(irq, cpumask)) {
 132                 cpumask_copy(desc->affinity, cpumask);
 133                 irq_set_thread_affinity(desc);
 134         }
 135 #endif
 136         desc->status |= IRQ_AFFINITY_SET;
 137         raw_spin_unlock_irqrestore(&desc->lock, flags);
 138         return 0;
 139 }
 140
 141 int irq_set_affinity_hint(unsigned int irq, const struct cpumask *m)
 142 {
 143         struct irq_desc *desc = irq_to_desc(irq);
 144         unsigned long flags;
 145
 146         if (!desc)
 147                 return -EINVAL;
 148
 149         raw_spin_lock_irqsave(&desc->lock, flags);
 150         desc->affinity_hint = m;
 151         raw_spin_unlock_irqrestore(&desc->lock, flags);
 152
 153         return 0;
 154 }
 155 EXPORT_SYMBOL_GPL(irq_set_affinity_hint);
 156
 157 #ifndef CONFIG_AUTO_IRQ_AFFINITY
 158 /*
 159  * Generic version of the affinity autoselector.
 160  */
 161 static int setup_affinity(unsigned int irq, struct irq_desc *desc)
 162 {
 163         if (!irq_can_set_affinity(irq))
 164                 return 0;
 165
 166         /*
 167          * Preserve an userspace affinity setup, but make sure that
 168          * one of the targets is online.
 169          */
 170         if (desc->status & (IRQ_AFFINITY_SET | IRQ_NO_BALANCING)) {
 171                 if (cpumask_any_and(desc->affinity, cpu_online_mask)
 172                     < nr_cpu_ids)
 173                         goto set_affinity;
 174                 else
 175                         desc->status &= ~IRQ_AFFINITY_SET;
 176         }
 177
 178         cpumask_and(desc->affinity, cpu_online_mask, irq_default_affinity);
 179 set_affinity:
 180         desc->chip->set_affinity(irq, desc->affinity);
 181
 182         return 0;
 183 }
 184 #else
 185 static inline int setup_affinity(unsigned int irq, struct irq_desc *d)
 186 {
 187         return irq_select_affinity(irq);
 188 }
 189 #endif
 190
 191 /*
 192  * Called when affinity is set via /proc/irq
 193  */
 194 int irq_select_affinity_usr(unsigned int irq)
 195 {
 196         struct irq_desc *desc = irq_to_desc(irq);
 197         unsigned long flags;
 198         int ret;
 199
 200         raw_spin_lock_irqsave(&desc->lock, flags);
 201         ret = setup_affinity(irq, desc);
 202         if (!ret)
 203                 irq_set_thread_affinity(desc);
 204         raw_spin_unlock_irqrestore(&desc->lock, flags);
 205
 206         return ret;
 207 }
 208
 209 #else
 210 static inline int setup_affinity(unsigned int irq, struct irq_desc *desc)
 211 {
 212         return 0;
 213 }
 214 #endif
 215
 216 void __disable_irq(struct irq_desc *desc, unsigned int irq, bool suspend)
 217 {
 218         if (suspend) {
 219                 if (!desc->action || (desc->action->flags & IRQF_NO_SUSPEND))
 220                         return;
 221                 desc->status |= IRQ_SUSPENDED;
 222         }
 223
 224         if (!desc->depth++) {
 225                 desc->status |= IRQ_DISABLED;
 226                 desc->chip->disable(irq);
 227         }
 228 }
 229
 230 /**
 231  *      disable_irq_nosync - disable an irq without waiting
 232  *      @irq: Interrupt to disable
 233  *
 234  *      Disable the selected interrupt line.  Disables and Enables are
 235  *      nested.
 236  *      Unlike disable_irq(), this function does not ensure existing
 237  *      instances of the IRQ handler have completed before returning.
 238  *
 239  *      This function may be called from IRQ context.
 240  */
 241 void disable_irq_nosync(unsigned int irq)
 242 {
 243         struct irq_desc *desc = irq_to_desc(irq);
 244         unsigned long flags;
 245
 246         if (!desc)
 247                 return;
 248
 249         chip_bus_lock(irq, desc);
 250         raw_spin_lock_irqsave(&desc->lock, flags);
 251         __disable_irq(desc, irq, false);
 252         raw_spin_unlock_irqrestore(&desc->lock, flags);
 253         chip_bus_sync_unlock(irq, desc);
 254 }
 255 EXPORT_SYMBOL(disable_irq_nosync);
 256
 257 /**
 258  *      disable_irq - disable an irq and wait for completion
 259  *      @irq: Interrupt to disable
 260  *
 261  *      Disable the selected interrupt line.  Enables and Disables are
 262  *      nested.
 263  *      This function waits for any pending IRQ handlers for this interrupt
 264  *      to complete before returning. If you use this function while
 265  *      holding a resource the IRQ handler may need you will deadlock.
 266  *
 267  *      This function may be called - with care - from IRQ context.
 268  */
 269 void disable_irq(unsigned int irq)
 270 {
 271         struct irq_desc *desc = irq_to_desc(irq);
 272
 273         if (!desc)
 274                 return;
 275
 276         disable_irq_nosync(irq);
 277         if (desc->action)
 278                 synchronize_irq(irq);
 279 }
 280 EXPORT_SYMBOL(disable_irq);
 281
 282 void __enable_irq(struct irq_desc *desc, unsigned int irq, bool resume)
 283 {
 284         if (resume) {
 285                 if (!(desc->status & IRQ_SUSPENDED)) {
 286                         if (!desc->action)
 287                                 return;
 288                         if (!(desc->action->flags & IRQF_FORCE_RESUME))
 289                                 return;
 290                         /* Pretend that it got disabled ! */
 291                         desc->depth++;
 292                 }
 293                 desc->status &= ~IRQ_SUSPENDED;
 294         }
 295
 296         switch (desc->depth) {
 297         case 0:
 298  err_out:
 299                 WARN(1, KERN_WARNING "Unbalanced enable for IRQ %d\n", irq);
 300                 break;
 301         case 1: {
 302                 unsigned int status = desc->status & ~IRQ_DISABLED;
 303
 304                 if (desc->status & IRQ_SUSPENDED)
 305                         goto err_out;
 306                 /* Prevent probing on this irq: */
 307                 desc->status = status | IRQ_NOPROBE;
 308                 check_irq_resend(desc, irq);
 309                 /* fall-through */
 310         }
 311         default:
 312                 desc->depth--;
 313         }
 314 }
 315
 316 /**
 317  *      enable_irq - enable handling of an irq
 318  *      @irq: Interrupt to enable
 319  *
 320  *      Undoes the effect of one call to disable_irq().  If this
 321  *      matches the last disable, processing of interrupts on this
 322  *      IRQ line is re-enabled.
 323  *
 324  *      This function may be called from IRQ context only when
 325  *      desc->chip->bus_lock and desc->chip->bus_sync_unlock are NULL !
 326  */
 327 void enable_irq(unsigned int irq)
 328 {
 329         struct irq_desc *desc = irq_to_desc(irq);
 330         unsigned long flags;
 331
 332         if (!desc)
 333                 return;
 334
 335         chip_bus_lock(irq, desc);
 336         raw_spin_lock_irqsave(&desc->lock, flags);
 337         __enable_irq(desc, irq, false);
 338         raw_spin_unlock_irqrestore(&desc->lock, flags);
 339         chip_bus_sync_unlock(irq, desc);
 340 }
 341 EXPORT_SYMBOL(enable_irq);
 342
 343 static int set_irq_wake_real(unsigned int irq, unsigned int on)
 344 {
 345         struct irq_desc *desc = irq_to_desc(irq);
 346         int ret = -ENXIO;
 347
 348         if (desc->chip->set_wake)
 349                 ret = desc->chip->set_wake(irq, on);
 350
 351         return ret;
 352 }
 353
 354 /**
 355  *      set_irq_wake - control irq power management wakeup
 356  *      @irq:   interrupt to control
 357  *      @on:    enable/disable power management wakeup
 358  *
 359  *      Enable/disable power management wakeup mode, which is
 360  *      disabled by default.  Enables and disables must match,
 361  *      just as they match for non-wakeup mode support.
 362  *
 363  *      Wakeup mode lets this IRQ wake the system from sleep
 364  *      states like "suspend to RAM".
 365  */
 366 int set_irq_wake(unsigned int irq, unsigned int on)
 367 {
 368         struct irq_desc *desc = irq_to_desc(irq);
 369         unsigned long flags;
 370         int ret = 0;
 371
 372         /* wakeup-capable irqs can be shared between drivers that
 373          * don't need to have the same sleep mode behaviors.
 374          */
 375         raw_spin_lock_irqsave(&desc->lock, flags);
 376         if (on) {
 377                 if (desc->wake_depth++ == 0) {
 378                         ret = set_irq_wake_real(irq, on);
 379                         if (ret)
 380                                 desc->wake_depth = 0;
 381                         else
 382                                 desc->status |= IRQ_WAKEUP;
 383                 }
 384         } else {
 385                 if (desc->wake_depth == 0) {
 386                         WARN(1, "Unbalanced IRQ %d wake disable\n", irq);
 387                 } else if (--desc->wake_depth == 0) {
 388                         ret = set_irq_wake_real(irq, on);
 389                         if (ret)
 390                                 desc->wake_depth = 1;
 391                         else
 392                                 desc->status &= ~IRQ_WAKEUP;
 393                 }
 394         }
 395
 396         raw_spin_unlock_irqrestore(&desc->lock, flags);
 397         return ret;
 398 }
 399 EXPORT_SYMBOL(set_irq_wake);
 400
 401 /*
 402  * Internal function that tells the architecture code whether a
 403  * particular irq has been exclusively allocated or is available
 404  * for driver use.
 405  */
 406 int can_request_irq(unsigned int irq, unsigned long irqflags)
 407 {
 408         struct irq_desc *desc = irq_to_desc(irq);
 409         struct irqaction *action;
 410         unsigned long flags;
 411
 412         if (!desc)
 413                 return 0;
 414
 415         if (desc->status & IRQ_NOREQUEST)
 416                 return 0;
 417
 418         raw_spin_lock_irqsave(&desc->lock, flags);
 419         action = desc->action;
 420         if (action)
 421                 if (irqflags & action->flags & IRQF_SHARED)
 422                         action = NULL;
 423
 424         raw_spin_unlock_irqrestore(&desc->lock, flags);
 425
 426         return !action;
 427 }
 428
 429 void compat_irq_chip_set_default_handler(struct irq_desc *desc)
 430 {
 431         /*
 432          * If the architecture still has not overriden
 433          * the flow handler then zap the default. This
 434          * should catch incorrect flow-type setting.
 435          */
 436         if (desc->handle_irq == &handle_bad_irq)
 437                 desc->handle_irq = NULL;
 438 }
 439
 440 int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
 441                 unsigned long flags)
 442 {
 443         int ret;
 444         struct irq_chip *chip = desc->chip;
 445
 446         if (!chip || !chip->set_type) {
 447                 /*
 448                  * IRQF_TRIGGER_* but the PIC does not support multiple
 449                  * flow-types?
 450                  */
 451                 pr_debug("No set_type function for IRQ %d (%s)\n", irq,
 452                                 chip ? (chip->name ? : "unknown") : "unknown");
 453                 return 0;
 454         }
 455
 456         /* caller masked out all except trigger mode flags */
 457         ret = chip->set_type(irq, flags);
 458
 459         if (ret)
 460                 pr_err("setting trigger mode %d for irq %u failed (%pF)\n",
 461                                 (int)flags, irq, chip->set_type);
 462         else {
 463                 if (flags & (IRQ_TYPE_LEVEL_LOW | IRQ_TYPE_LEVEL_HIGH))
 464                         flags |= IRQ_LEVEL;
 465                 /* note that IRQF_TRIGGER_MASK == IRQ_TYPE_SENSE_MASK */
 466                 desc->status &= ~(IRQ_LEVEL | IRQ_TYPE_SENSE_MASK);
 467                 desc->status |= flags;
 468
 469                 if (chip != desc->chip)
 470                         irq_chip_set_defaults(desc->chip);
 471         }
 472
 473         return ret;
 474 }
 475
 476 /*
 477  * Default primary interrupt handler for threaded interrupts. Is
 478  * assigned as primary handler when request_threaded_irq is called
 479  * with handler == NULL. Useful for oneshot interrupts.
 480  */
 481 static irqreturn_t irq_default_primary_handler(int irq, void *dev_id)
 482 {
 483         return IRQ_WAKE_THREAD;
 484 }
 485
 486 /*
 487  * Primary handler for nested threaded interrupts. Should never be
 488  * called.
 489  */
 490 static irqreturn_t irq_nested_primary_handler(int irq, void *dev_id)
 491 {
 492         WARN(1, "Primary handler called for nested irq %d\n", irq);
 493         return IRQ_NONE;
 494 }
 495
 496 static int irq_wait_for_interrupt(struct irqaction *action)
 497 {
 498         while (!kthread_should_stop()) {
 499                 set_current_state(TASK_INTERRUPTIBLE);
 500
 501                 if (test_and_clear_bit(IRQTF_RUNTHREAD,
 502                                        &action->thread_flags)) {
 503                         __set_current_state(TASK_RUNNING);
 504                         return 0;
 505                 }
 506                 schedule();
 507         }
 508         return -1;
 509 }
 510
 511 /*
 512  * Oneshot interrupts keep the irq line masked until the threaded
 513  * handler finished. unmask if the interrupt has not been disabled and
 514  * is marked MASKED.
 515  */
 516 static void irq_finalize_oneshot(unsigned int irq, struct irq_desc *desc)
 517 {
 518 again:
 519         chip_bus_lock(irq, desc);
 520         raw_spin_lock_irq(&desc->lock);
 521
 522         /*
 523          * Implausible though it may be we need to protect us against
 524          * the following scenario:
 525          *
 526          * The thread is faster done than the hard interrupt handler
 527          * on the other CPU. If we unmask the irq line then the
 528          * interrupt can come in again and masks the line, leaves due
 529          * to IRQ_INPROGRESS and the irq line is masked forever.
 530          */
 531         if (unlikely(desc->status & IRQ_INPROGRESS)) {
 532                 raw_spin_unlock_irq(&desc->lock);
 533                 chip_bus_sync_unlock(irq, desc);
 534                 cpu_relax();
 535                 goto again;
 536         }
 537
 538         if (!(desc->status & IRQ_DISABLED) && (desc->status & IRQ_MASKED)) {
 539                 desc->status &= ~IRQ_MASKED;
 540                 desc->chip->unmask(irq);
 541         }
 542         raw_spin_unlock_irq(&desc->lock);
 543         chip_bus_sync_unlock(irq, desc);
 544 }
 545
 546 #ifdef CONFIG_SMP
 547 /*
 548  * Check whether we need to change the affinity of the interrupt thread.
 549  */
 550 static void
 551 irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action)
 552 {
 553         cpumask_var_t mask;
 554
 555         if (!test_and_clear_bit(IRQTF_AFFINITY, &action->thread_flags))
 556                 return;
 557
 558         /*
 559          * In case we are out of memory we set IRQTF_AFFINITY again and
 560          * try again next time
 561          */
 562         if (!alloc_cpumask_var(&mask, GFP_KERNEL)) {
 563                 set_bit(IRQTF_AFFINITY, &action->thread_flags);
 564                 return;
 565         }
 566
 567         raw_spin_lock_irq(&desc->lock);
 568         cpumask_copy(mask, desc->affinity);
 569         raw_spin_unlock_irq(&desc->lock);
 570
 571         set_cpus_allowed_ptr(current, mask);
 572         free_cpumask_var(mask);
 573 }
 574 #else
 575 static inline void
 576 irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action) { }
 577 #endif
 578
 579 /*
 580  * Interrupt handler thread
 581  */
 582 static int irq_thread(void *data)
 583 {
 584         struct sched_param param = { .sched_priority = MAX_USER_RT_PRIO/2, };
 585         struct irqaction *action = data;
 586         struct irq_desc *desc = irq_to_desc(action->irq);
 587         int wake, oneshot = desc->status & IRQ_ONESHOT;
 588
 589         sched_setscheduler(current, SCHED_FIFO, &param);
 590         current->irqaction = action;
 591
 592         while (!irq_wait_for_interrupt(action)) {
 593
 594                 irq_thread_check_affinity(desc, action);
 595
 596                 atomic_inc(&desc->threads_active);
 597
 598                 raw_spin_lock_irq(&desc->lock);
 599                 if (unlikely(desc->status & IRQ_DISABLED)) {
 600                         /*
 601                          * CHECKME: We might need a dedicated
 602                          * IRQ_THREAD_PENDING flag here, which
 603                          * retriggers the thread in check_irq_resend()
 604                          * but AFAICT IRQ_PENDING should be fine as it
 605                          * retriggers the interrupt itself --- tglx
 606                          */
 607                         desc->status |= IRQ_PENDING;
 608                         raw_spin_unlock_irq(&desc->lock);
 609                 } else {
 610                         raw_spin_unlock_irq(&desc->lock);
 611
 612                         action->thread_fn(action->irq, action->dev_id);
 613
 614                         if (oneshot)
 615                                 irq_finalize_oneshot(action->irq, desc);
 616                 }
 617
 618                 wake = atomic_dec_and_test(&desc->threads_active);
 619
 620                 if (wake && waitqueue_active(&desc->wait_for_threads))
 621                         wake_up(&desc->wait_for_threads);
 622         }
 623
 624         /*
 625          * Clear irqaction. Otherwise exit_irq_thread() would make
 626          * fuzz about an active irq thread going into nirvana.
 627          */
 628         current->irqaction = NULL;
 629         return 0;
 630 }
 631
 632 /*
 633  * Called from do_exit()
 634  */
 635 void exit_irq_thread(void)
 636 {
 637         struct task_struct *tsk = current;
 638
 639         if (!tsk->irqaction)
 640                 return;
 641
 642         printk(KERN_ERR
 643                "exiting task \"%s\" (%d) is an active IRQ thread (irq %d)\n",
 644                tsk->comm ? tsk->comm : "", tsk->pid, tsk->irqaction->irq);
 645
 646         /*
 647          * Set the THREAD DIED flag to prevent further wakeups of the
 648          * soon to be gone threaded handler.
 649          */
 650         set_bit(IRQTF_DIED, &tsk->irqaction->flags);
 651 }
 652
 653 /*
 654  * Internal function to register an irqaction - typically used to
 655  * allocate special interrupts that are part of the architecture.
 656  */
 657 static int
 658 __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
 659 {
 660         struct irqaction *old, **old_ptr;
 661         const char *old_name = NULL;
 662         unsigned long flags;
 663         int nested, shared = 0;
 664         int ret;
 665
 666         if (!desc)
 667                 return -EINVAL;
 668
 669         if (desc->chip == &no_irq_chip)
 670                 return -ENOSYS;
 671         /*
 672          * Some drivers like serial.c use request_irq() heavily,
 673          * so we have to be careful not to interfere with a
 674          * running system.
 675          */
 676         if (new->flags & IRQF_SAMPLE_RANDOM) {
 677                 /*
 678                  * This function might sleep, we want to call it first,
 679                  * outside of the atomic block.
 680                  * Yes, this might clear the entropy pool if the wrong
 681                  * driver is attempted to be loaded, without actually
 682                  * installing a new handler, but is this really a problem,
 683                  * only the sysadmin is able to do this.
 684                  */
 685                 rand_initialize_irq(irq);
 686         }
 687
 688         /* Oneshot interrupts are not allowed with shared */
 689         if ((new->flags & IRQF_ONESHOT) && (new->flags & IRQF_SHARED))
 690                 return -EINVAL;
 691
 692         /*
 693          * Check whether the interrupt nests into another interrupt
 694          * thread.
 695          */
 696         nested = desc->status & IRQ_NESTED_THREAD;
 697         if (nested) {
 698                 if (!new->thread_fn)
 699                         return -EINVAL;
 700                 /*
 701                  * Replace the primary handler which was provided from
 702                  * the driver for non nested interrupt handling by the
 703                  * dummy function which warns when called.
 704                  */
 705                 new->handler = irq_nested_primary_handler;
 706         }
 707
 708         /*
 709          * Create a handler thread when a thread function is supplied
 710          * and the interrupt does not nest into another interrupt
 711          * thread.
 712          */
 713         if (new->thread_fn && !nested) {
 714                 struct task_struct *t;
 715
 716                 t = kthread_create(irq_thread, new, "irq/%d-%s", irq,
 717                                    new->name);
 718                 if (IS_ERR(t))
 719                         return PTR_ERR(t);
 720                 /*
 721                  * We keep the reference to the task struct even if
 722                  * the thread dies to avoid that the interrupt code
 723                  * references an already freed task_struct.
 724                  */
 725                 get_task_struct(t);
 726                 new->thread = t;
 727         }
 728
 729         /*
 730          * The following block of code has to be executed atomically
 731          */
 732         raw_spin_lock_irqsave(&desc->lock, flags);
 733         old_ptr = &desc->action;
 734         old = *old_ptr;
 735         if (old) {
 736                 /*
 737                  * Can't share interrupts unless both agree to and are
 738                  * the same type (level, edge, polarity). So both flag
 739                  * fields must have IRQF_SHARED set and the bits which
 740                  * set the trigger type must match.
 741                  */
 742                 if (!((old->flags & new->flags) & IRQF_SHARED) ||
 743                     ((old->flags ^ new->flags) & IRQF_TRIGGER_MASK)) {
 744                         old_name = old->name;
 745                         goto mismatch;
 746                 }
 747
 748 #if defined(CONFIG_IRQ_PER_CPU)
 749                 /* All handlers must agree on per-cpuness */
 750                 if ((old->flags & IRQF_PERCPU) !=
 751                     (new->flags & IRQF_PERCPU))
 752                         goto mismatch;
 753 #endif
 754
 755                 /* add new interrupt at end of irq queue */
 756                 do {
 757                         old_ptr = &old->next;
 758                         old = *old_ptr;
 759                 } while (old);
 760                 shared = 1;
 761         }
 762
 763         if (!shared) {
 764                 irq_chip_set_defaults(desc->chip);
 765
 766                 init_waitqueue_head(&desc->wait_for_threads);
 767
 768                 /* Setup the type (level, edge polarity) if configured: */
 769                 if (new->flags & IRQF_TRIGGER_MASK) {
 770                         ret = __irq_set_trigger(desc, irq,
 771                                         new->flags & IRQF_TRIGGER_MASK);
 772
 773                         if (ret)
 774                                 goto out_thread;
 775                 } else
 776                         compat_irq_chip_set_default_handler(desc);
 777 #if defined(CONFIG_IRQ_PER_CPU)
 778                 if (new->flags & IRQF_PERCPU)
 779                         desc->status |= IRQ_PER_CPU;
 780 #endif
 781
 782                 desc->status &= ~(IRQ_AUTODETECT | IRQ_WAITING | IRQ_ONESHOT |
 783                                   IRQ_INPROGRESS | IRQ_SPURIOUS_DISABLED);
 784
 785                 if (new->flags & IRQF_ONESHOT)
 786                         desc->status |= IRQ_ONESHOT;
 787
 788                 if (!(desc->status & IRQ_NOAUTOEN)) {
 789                         desc->depth = 0;
 790                         desc->status &= ~IRQ_DISABLED;
 791                         desc->chip->startup(irq);
 792                 } else
 793                         /* Undo nested disables: */
 794                         desc->depth = 1;
 795
 796                 /* Exclude IRQ from balancing if requested */
 797                 if (new->flags & IRQF_NOBALANCING)
 798                         desc->status |= IRQ_NO_BALANCING;
 799
 800                 /* Set default affinity mask once everything is setup */
 801                 setup_affinity(irq, desc);
 802
 803         } else if ((new->flags & IRQF_TRIGGER_MASK)
 804                         && (new->flags & IRQF_TRIGGER_MASK)
 805                                 != (desc->status & IRQ_TYPE_SENSE_MASK)) {
 806                 /* hope the handler works with the actual trigger mode... */
 807                 pr_warning("IRQ %d uses trigger mode %d; requested %d\n",
 808                                 irq, (int)(desc->status & IRQ_TYPE_SENSE_MASK),
 809                                 (int)(new->flags & IRQF_TRIGGER_MASK));
 810         }
 811
 812         new->irq = irq;
 813         *old_ptr = new;
 814
 815         /* Reset broken irq detection when installing new handler */
 816         desc->irq_count = 0;
 817         desc->irqs_unhandled = 0;
 818
 819         /*
 820          * Check whether we disabled the irq via the spurious handler
 821          * before. Reenable it and give it another chance.
 822          */
 823         if (shared && (desc->status & IRQ_SPURIOUS_DISABLED)) {
 824                 desc->status &= ~IRQ_SPURIOUS_DISABLED;
 825                 __enable_irq(desc, irq, false);
 826         }
 827
 828         raw_spin_unlock_irqrestore(&desc->lock, flags);
 829
 830         /*
 831          * Strictly no need to wake it up, but hung_task complains
 832          * when no hard interrupt wakes the thread up.
 833          */
 834         if (new->thread)
 835                 wake_up_process(new->thread);
 836
 837         register_irq_proc(irq, desc);
 838         new->dir = NULL;
 839         register_handler_proc(irq, new);
 840
 841         return 0;
 842
 843 mismatch:
 844 #ifdef CONFIG_DEBUG_SHIRQ
 845         if (!(new->flags & IRQF_PROBE_SHARED)) {
 846                 printk(KERN_ERR "IRQ handler type mismatch for IRQ %d\n", irq);
 847                 if (old_name)
 848                         printk(KERN_ERR "current handler: %s\n", old_name);
 849                 dump_stack();
 850         }
 851 #endif
 852         ret = -EBUSY;
 853
 854 out_thread:
 855         raw_spin_unlock_irqrestore(&desc->lock, flags);
 856         if (new->thread) {
 857                 struct task_struct *t = new->thread;
 858
 859                 new->thread = NULL;
 860                 if (likely(!test_bit(IRQTF_DIED, &new->thread_flags)))
 861                         kthread_stop(t);
 862                 put_task_struct(t);
 863         }
 864         return ret;
 865 }
 866
 867 /**
 868  *      setup_irq - setup an interrupt
 869  *      @irq: Interrupt line to setup
 870  *      @act: irqaction for the interrupt
 871  *
 872  * Used to statically setup interrupts in the early boot process.
 873  */
 874 int setup_irq(unsigned int irq, struct irqaction *act)
 875 {
 876         struct irq_desc *desc = irq_to_desc(irq);
 877
 878         return __setup_irq(irq, desc, act);
 879 }
 880 EXPORT_SYMBOL_GPL(setup_irq);
 881
 882  /*
 883  * Internal function to unregister an irqaction - used to free
 884  * regular and special interrupts that are part of the architecture.
 885  */
 886 static struct irqaction *__free_irq(unsigned int irq, void *dev_id)
 887 {
 888         struct irq_desc *desc = irq_to_desc(irq);
 889         struct irqaction *action, **action_ptr;
 890         unsigned long flags;
 891
 892         WARN(in_interrupt(), "Trying to free IRQ %d from IRQ context!\n", irq);
 893
 894         if (!desc)
 895                 return NULL;
 896
 897         raw_spin_lock_irqsave(&desc->lock, flags);
 898
 899         /*
 900          * There can be multiple actions per IRQ descriptor, find the right
 901          * one based on the dev_id:
 902          */
 903         action_ptr = &desc->action;
 904         for (;;) {
 905                 action = *action_ptr;
 906
 907                 if (!action) {
 908                         WARN(1, "Trying to free already-free IRQ %d\n", irq);
 909                         raw_spin_unlock_irqrestore(&desc->lock, flags);
 910
 911                         return NULL;
 912                 }
 913
 914                 if (action->dev_id == dev_id)
 915                         break;
 916                 action_ptr = &action->next;
 917         }
 918
 919         /* Found it - now remove it from the list of entries: */
 920         *action_ptr = action->next;
 921
 922         /* Currently used only by UML, might disappear one day: */
 923 #ifdef CONFIG_IRQ_RELEASE_METHOD
 924         if (desc->chip->release)
 925                 desc->chip->release(irq, dev_id);
 926 #endif
 927
 928         /* If this was the last handler, shut down the IRQ line: */
 929         if (!desc->action) {
 930                 desc->status |= IRQ_DISABLED;
 931                 if (desc->chip->shutdown)
 932                         desc->chip->shutdown(irq);
 933                 else
 934                         desc->chip->disable(irq);
 935         }
 936
 937 #ifdef CONFIG_SMP
 938         /* make sure affinity_hint is cleaned up */
 939         if (WARN_ON_ONCE(desc->affinity_hint))
 940                 desc->affinity_hint = NULL;
 941 #endif
 942
 943         raw_spin_unlock_irqrestore(&desc->lock, flags);
 944
 945         unregister_handler_proc(irq, action);
 946
 947         /* Make sure it's not being used on another CPU: */
 948         synchronize_irq(irq);
 949
 950 #ifdef CONFIG_DEBUG_SHIRQ
 951         /*
 952          * It's a shared IRQ -- the driver ought to be prepared for an IRQ
 953          * event to happen even now it's being freed, so let's make sure that
 954          * is so by doing an extra call to the handler ....
 955          *
 956          * ( We do this after actually deregistering it, to make sure that a
 957          *   'real' IRQ doesn't run in * parallel with our fake. )
 958          */
 959         if (action->flags & IRQF_SHARED) {
 960                 local_irq_save(flags);
 961                 action->handler(irq, dev_id);
 962                 local_irq_restore(flags);
 963         }
 964 #endif
 965
 966         if (action->thread) {
 967                 if (!test_bit(IRQTF_DIED, &action->thread_flags))
 968                         kthread_stop(action->thread);
 969                 put_task_struct(action->thread);
 970         }
 971
 972         return action;
 973 }
 974
 975 /**
 976  *      remove_irq - free an interrupt
 977  *      @irq: Interrupt line to free
 978  *      @act: irqaction for the interrupt
 979  *
 980  * Used to remove interrupts statically setup by the early boot process.
 981  */
 982 void remove_irq(unsigned int irq, struct irqaction *act)
 983 {
 984         __free_irq(irq, act->dev_id);
 985 }
 986 EXPORT_SYMBOL_GPL(remove_irq);
 987
 988 /**
 989  *      free_irq - free an interrupt allocated with request_irq
 990  *      @irq: Interrupt line to free
 991  *      @dev_id: Device identity to free
 992  *
 993  *      Remove an interrupt handler. The handler is removed and if the
 994  *      interrupt line is no longer in use by any driver it is disabled.
 995  *      On a shared IRQ the caller must ensure the interrupt is disabled
 996  *      on the card it drives before calling this function. The function
 997  *      does not return until any executing interrupts for this IRQ
 998  *      have completed.
 999  *
1000  *      This function must not be called from interrupt context.
1001  */
1002 void free_irq(unsigned int irq, void *dev_id)
1003 {
1004         struct irq_desc *desc = irq_to_desc(irq);
1005
1006         if (!desc)
1007                 return;
1008
1009         chip_bus_lock(irq, desc);
1010         kfree(__free_irq(irq, dev_id));
1011         chip_bus_sync_unlock(irq, desc);
1012 }
1013 EXPORT_SYMBOL(free_irq);
1014
1015 /**
1016  *      request_threaded_irq - allocate an interrupt line
1017  *      @irq: Interrupt line to allocate
1018  *      @handler: Function to be called when the IRQ occurs.
1019  *                Primary handler for threaded interrupts
1020  *                If NULL and thread_fn != NULL the default
1021  *                primary handler is installed
1022  *      @thread_fn: Function called from the irq handler thread
1023  *                  If NULL, no irq thread is created
1024  *      @irqflags: Interrupt type flags
1025  *      @devname: An ascii name for the claiming device
1026  *      @dev_id: A cookie passed back to the handler function
1027  *
1028  *      This call allocates interrupt resources and enables the
1029  *      interrupt line and IRQ handling. From the point this
1030  *      call is made your handler function may be invoked. Since
1031  *      your handler function must clear any interrupt the board
1032  *      raises, you must take care both to initialise your hardware
1033  *      and to set up the interrupt handler in the right order.
1034  *
1035  *      If you want to set up a threaded irq handler for your device
1036  *      then you need to supply @handler and @thread_fn. @handler ist
1037  *      still called in hard interrupt context and has to check
1038  *      whether the interrupt originates from the device. If yes it
1039  *      needs to disable the interrupt on the device and return
1040  *      IRQ_WAKE_THREAD which will wake up the handler thread and run
1041  *      @thread_fn. This split handler design is necessary to support
1042  *      shared interrupts.
1043  *
1044  *      Dev_id must be globally unique. Normally the address of the
1045  *      device data structure is used as the cookie. Since the handler
1046  *      receives this value it makes sense to use it.
1047  *
1048  *      If your interrupt is shared you must pass a non NULL dev_id
1049  *      as this is required when freeing the interrupt.
1050  *
1051  *      Flags:
1052  *
1053  *      IRQF_SHARED             Interrupt is shared
1054  *      IRQF_SAMPLE_RANDOM      The interrupt can be used for entropy
1055  *      IRQF_TRIGGER_*          Specify active edge(s) or level
1056  *
1057  */
1058 int request_threaded_irq(unsigned int irq, irq_handler_t handler,
1059                          irq_handler_t thread_fn, unsigned long irqflags,
1060                          const char *devname, void *dev_id)
1061 {
1062         struct irqaction *action;
1063         struct irq_desc *desc;
1064         int retval;
1065
1066         /*
1067          * Sanity-check: shared interrupts must pass in a real dev-ID,
1068          * otherwise we'll have trouble later trying to figure out
1069          * which interrupt is which (messes up the interrupt freeing
1070          * logic etc).
1071          */
1072         if ((irqflags & IRQF_SHARED) && !dev_id)
1073                 return -EINVAL;
1074
1075         desc = irq_to_desc(irq);
1076         if (!desc)
1077                 return -EINVAL;
1078
1079         if (desc->status & IRQ_NOREQUEST)
1080                 return -EINVAL;
1081
1082         if (!handler) {
1083                 if (!thread_fn)
1084                         return -EINVAL;
1085                 handler = irq_default_primary_handler;
1086         }
1087
1088         action = kzalloc(sizeof(struct irqaction), GFP_KERNEL);
1089         if (!action)
1090                 return -ENOMEM;
1091
1092         action->handler = handler;
1093         action->thread_fn = thread_fn;
1094         action->flags = irqflags;
1095         action->name = devname;
1096         action->dev_id = dev_id;
1097
1098         chip_bus_lock(irq, desc);
1099         retval = __setup_irq(irq, desc, action);
1100         chip_bus_sync_unlock(irq, desc);
1101
1102         if (retval)
1103                 kfree(action);
1104
1105 #ifdef CONFIG_DEBUG_SHIRQ_FIXME
1106         if (!retval && (irqflags & IRQF_SHARED)) {
1107                 /*
1108                  * It's a shared IRQ -- the driver ought to be prepared for it
1109                  * to happen immediately, so let's make sure....
1110                  * We disable the irq to make sure that a 'real' IRQ doesn't
1111                  * run in parallel with our fake.
1112                  */
1113                 unsigned long flags;
1114
1115                 disable_irq(irq);
1116                 local_irq_save(flags);
1117
1118                 handler(irq, dev_id);
1119
1120                 local_irq_restore(flags);
1121                 enable_irq(irq);
1122         }
1123 #endif
1124         return retval;
1125 }
1126 EXPORT_SYMBOL(request_threaded_irq);
1127
1128 /**
1129  *      request_any_context_irq - allocate an interrupt line
1130  *      @irq: Interrupt line to allocate
1131  *      @handler: Function to be called when the IRQ occurs.
1132  *                Threaded handler for threaded interrupts.
1133  *      @flags: Interrupt type flags
1134  *      @name: An ascii name for the claiming device
1135  *      @dev_id: A cookie passed back to the handler function
1136  *
1137  *      This call allocates interrupt resources and enables the
1138  *      interrupt line and IRQ handling. It selects either a
1139  *      hardirq or threaded handling method depending on the
1140  *      context.
1141  *
1142  *      On failure, it returns a negative value. On success,
1143  *      it returns either IRQC_IS_HARDIRQ or IRQC_IS_NESTED.
1144  */
1145 int request_any_context_irq(unsigned int irq, irq_handler_t handler,
1146                             unsigned long flags, const char *name, void *dev_id)
1147 {
1148         struct irq_desc *desc = irq_to_desc(irq);
1149         int ret;
1150
1151         if (!desc)
1152                 return -EINVAL;
1153
1154         if (desc->status & IRQ_NESTED_THREAD) {
1155                 ret = request_threaded_irq(irq, NULL, handler,
1156                                            flags, name, dev_id);
1157                 return !ret ? IRQC_IS_NESTED : ret;
1158         }
1159
1160         ret = request_irq(irq, handler, flags, name, dev_id);
1161         return !ret ? IRQC_IS_HARDIRQ : ret;
1162 }
1163 EXPORT_SYMBOL_GPL(request_any_context_irq);