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