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         if (WARN(!desc->irq_data.chip || !desc->irq_data.chip->irq_enable,
 328             KERN_ERR "enable_irq before setup/request_irq: irq %u\n", irq))
 329                 return;
 330
 331         chip_bus_lock(desc);
 332         raw_spin_lock_irqsave(&desc->lock, flags);
 333         __enable_irq(desc, irq, false);
 334         raw_spin_unlock_irqrestore(&desc->lock, flags);
 335         chip_bus_sync_unlock(desc);
 336 }
 337 EXPORT_SYMBOL(enable_irq);
 338
 339 static int set_irq_wake_real(unsigned int irq, unsigned int on)
 340 {
 341         struct irq_desc *desc = irq_to_desc(irq);
 342         int ret = -ENXIO;
 343
 344         if (desc->irq_data.chip->irq_set_wake)
 345                 ret = desc->irq_data.chip->irq_set_wake(&desc->irq_data, on);
 346
 347         return ret;
 348 }
 349
 350 /**
 351  *      set_irq_wake - control irq power management wakeup
 352  *      @irq:   interrupt to control
 353  *      @on:    enable/disable power management wakeup
 354  *
 355  *      Enable/disable power management wakeup mode, which is
 356  *      disabled by default.  Enables and disables must match,
 357  *      just as they match for non-wakeup mode support.
 358  *
 359  *      Wakeup mode lets this IRQ wake the system from sleep
 360  *      states like "suspend to RAM".
 361  */
 362 int set_irq_wake(unsigned int irq, unsigned int on)
 363 {
 364         struct irq_desc *desc = irq_to_desc(irq);
 365         unsigned long flags;
 366         int ret = 0;
 367
 368         /* wakeup-capable irqs can be shared between drivers that
 369          * don't need to have the same sleep mode behaviors.
 370          */
 371         raw_spin_lock_irqsave(&desc->lock, flags);
 372         if (on) {
 373                 if (desc->wake_depth++ == 0) {
 374                         ret = set_irq_wake_real(irq, on);
 375                         if (ret)
 376                                 desc->wake_depth = 0;
 377                         else
 378                                 desc->status |= IRQ_WAKEUP;
 379                 }
 380         } else {
 381                 if (desc->wake_depth == 0) {
 382                         WARN(1, "Unbalanced IRQ %d wake disable\n", irq);
 383                 } else if (--desc->wake_depth == 0) {
 384                         ret = set_irq_wake_real(irq, on);
 385                         if (ret)
 386                                 desc->wake_depth = 1;
 387                         else
 388                                 desc->status &= ~IRQ_WAKEUP;
 389                 }
 390         }
 391
 392         raw_spin_unlock_irqrestore(&desc->lock, flags);
 393         return ret;
 394 }
 395 EXPORT_SYMBOL(set_irq_wake);
 396
 397 /*
 398  * Internal function that tells the architecture code whether a
 399  * particular irq has been exclusively allocated or is available
 400  * for driver use.
 401  */
 402 int can_request_irq(unsigned int irq, unsigned long irqflags)
 403 {
 404         struct irq_desc *desc = irq_to_desc(irq);
 405         struct irqaction *action;
 406         unsigned long flags;
 407
 408         if (!desc)
 409                 return 0;
 410
 411         if (desc->status & IRQ_NOREQUEST)
 412                 return 0;
 413
 414         raw_spin_lock_irqsave(&desc->lock, flags);
 415         action = desc->action;
 416         if (action)
 417                 if (irqflags & action->flags & IRQF_SHARED)
 418                         action = NULL;
 419
 420         raw_spin_unlock_irqrestore(&desc->lock, flags);
 421
 422         return !action;
 423 }
 424
 425 void compat_irq_chip_set_default_handler(struct irq_desc *desc)
 426 {
 427         /*
 428          * If the architecture still has not overriden
 429          * the flow handler then zap the default. This
 430          * should catch incorrect flow-type setting.
 431          */
 432         if (desc->handle_irq == &handle_bad_irq)
 433                 desc->handle_irq = NULL;
 434 }
 435
 436 int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
 437                       unsigned long flags)
 438 {
 439         int ret;
 440         struct irq_chip *chip = desc->irq_data.chip;
 441
 442         if (!chip || !chip->irq_set_type) {
 443                 /*
 444                  * IRQF_TRIGGER_* but the PIC does not support multiple
 445                  * flow-types?
 446                  */
 447                 pr_debug("No set_type function for IRQ %d (%s)\n", irq,
 448                                 chip ? (chip->name ? : "unknown") : "unknown");
 449                 return 0;
 450         }
 451
 452         /* caller masked out all except trigger mode flags */
 453         ret = chip->irq_set_type(&desc->irq_data, flags);
 454
 455         if (ret)
 456                 pr_err("setting trigger mode %lu for irq %u failed (%pF)\n",
 457                        flags, irq, chip->irq_set_type);
 458         else {
 459                 if (flags & (IRQ_TYPE_LEVEL_LOW | IRQ_TYPE_LEVEL_HIGH))
 460                         flags |= IRQ_LEVEL;
 461                 /* note that IRQF_TRIGGER_MASK == IRQ_TYPE_SENSE_MASK */
 462                 desc->status &= ~(IRQ_LEVEL | IRQ_TYPE_SENSE_MASK);
 463                 desc->status |= flags;
 464
 465                 if (chip != desc->irq_data.chip)
 466                         irq_chip_set_defaults(desc->irq_data.chip);
 467         }
 468
 469         return ret;
 470 }
 471
 472 /*
 473  * Default primary interrupt handler for threaded interrupts. Is
 474  * assigned as primary handler when request_threaded_irq is called
 475  * with handler == NULL. Useful for oneshot interrupts.
 476  */
 477 static irqreturn_t irq_default_primary_handler(int irq, void *dev_id)
 478 {
 479         return IRQ_WAKE_THREAD;
 480 }
 481
 482 /*
 483  * Primary handler for nested threaded interrupts. Should never be
 484  * called.
 485  */
 486 static irqreturn_t irq_nested_primary_handler(int irq, void *dev_id)
 487 {
 488         WARN(1, "Primary handler called for nested irq %d\n", irq);
 489         return IRQ_NONE;
 490 }
 491
 492 static int irq_wait_for_interrupt(struct irqaction *action)
 493 {
 494         while (!kthread_should_stop()) {
 495                 set_current_state(TASK_INTERRUPTIBLE);
 496
 497                 if (test_and_clear_bit(IRQTF_RUNTHREAD,
 498                                        &action->thread_flags)) {
 499                         __set_current_state(TASK_RUNNING);
 500                         return 0;
 501                 }
 502                 schedule();
 503         }
 504         return -1;
 505 }
 506
 507 /*
 508  * Oneshot interrupts keep the irq line masked until the threaded
 509  * handler finished. unmask if the interrupt has not been disabled and
 510  * is marked MASKED.
 511  */
 512 static void irq_finalize_oneshot(unsigned int irq, struct irq_desc *desc)
 513 {
 514 again:
 515         chip_bus_lock(desc);
 516         raw_spin_lock_irq(&desc->lock);
 517
 518         /*
 519          * Implausible though it may be we need to protect us against
 520          * the following scenario:
 521          *
 522          * The thread is faster done than the hard interrupt handler
 523          * on the other CPU. If we unmask the irq line then the
 524          * interrupt can come in again and masks the line, leaves due
 525          * to IRQ_INPROGRESS and the irq line is masked forever.
 526          */
 527         if (unlikely(desc->status & IRQ_INPROGRESS)) {
 528                 raw_spin_unlock_irq(&desc->lock);
 529                 chip_bus_sync_unlock(desc);
 530                 cpu_relax();
 531                 goto again;
 532         }
 533
 534         if (!(desc->status & IRQ_DISABLED) && (desc->status & IRQ_MASKED)) {
 535                 desc->status &= ~IRQ_MASKED;
 536                 desc->irq_data.chip->irq_unmask(&desc->irq_data);
 537         }
 538         raw_spin_unlock_irq(&desc->lock);
 539         chip_bus_sync_unlock(desc);
 540 }
 541
 542 #ifdef CONFIG_SMP
 543 /*
 544  * Check whether we need to change the affinity of the interrupt thread.
 545  */
 546 static void
 547 irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action)
 548 {
 549         cpumask_var_t mask;
 550
 551         if (!test_and_clear_bit(IRQTF_AFFINITY, &action->thread_flags))
 552                 return;
 553
 554         /*
 555          * In case we are out of memory we set IRQTF_AFFINITY again and
 556          * try again next time
 557          */
 558         if (!alloc_cpumask_var(&mask, GFP_KERNEL)) {
 559                 set_bit(IRQTF_AFFINITY, &action->thread_flags);
 560                 return;
 561         }
 562
 563         raw_spin_lock_irq(&desc->lock);
 564         cpumask_copy(mask, desc->irq_data.affinity);
 565         raw_spin_unlock_irq(&desc->lock);
 566
 567         set_cpus_allowed_ptr(current, mask);
 568         free_cpumask_var(mask);
 569 }
 570 #else
 571 static inline void
 572 irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action) { }
 573 #endif
 574
 575 /*
 576  * Interrupt handler thread
 577  */
 578 static int irq_thread(void *data)
 579 {
 580         static struct sched_param param = {
 581                 .sched_priority = MAX_USER_RT_PRIO/2,
 582         };
 583         struct irqaction *action = data;
 584         struct irq_desc *desc = irq_to_desc(action->irq);
 585         int wake, oneshot = desc->status & IRQ_ONESHOT;
 586
 587         sched_setscheduler(current, SCHED_FIFO, &param);
 588         current->irqaction = action;
 589
 590         while (!irq_wait_for_interrupt(action)) {
 591
 592                 irq_thread_check_affinity(desc, action);
 593
 594                 atomic_inc(&desc->threads_active);
 595
 596                 raw_spin_lock_irq(&desc->lock);
 597                 if (unlikely(desc->status & IRQ_DISABLED)) {
 598                         /*
 599                          * CHECKME: We might need a dedicated
 600                          * IRQ_THREAD_PENDING flag here, which
 601                          * retriggers the thread in check_irq_resend()
 602                          * but AFAICT IRQ_PENDING should be fine as it
 603                          * retriggers the interrupt itself --- tglx
 604                          */
 605                         desc->status |= IRQ_PENDING;
 606                         raw_spin_unlock_irq(&desc->lock);
 607                 } else {
 608                         raw_spin_unlock_irq(&desc->lock);
 609
 610                         action->thread_fn(action->irq, action->dev_id);
 611
 612                         if (oneshot)
 613                                 irq_finalize_oneshot(action->irq, desc);
 614                 }
 615
 616                 wake = atomic_dec_and_test(&desc->threads_active);
 617
 618                 if (wake && waitqueue_active(&desc->wait_for_threads))
 619                         wake_up(&desc->wait_for_threads);
 620         }
 621
 622         /*
 623          * Clear irqaction. Otherwise exit_irq_thread() would make
 624          * fuzz about an active irq thread going into nirvana.
 625          */
 626         current->irqaction = NULL;
 627         return 0;
 628 }
 629
 630 /*
 631  * Called from do_exit()
 632  */
 633 void exit_irq_thread(void)
 634 {
 635         struct task_struct *tsk = current;
 636
 637         if (!tsk->irqaction)
 638                 return;
 639
 640         printk(KERN_ERR
 641                "exiting task \"%s\" (%d) is an active IRQ thread (irq %d)\n",
 642                tsk->comm ? tsk->comm : "", tsk->pid, tsk->irqaction->irq);
 643
 644         /*
 645          * Set the THREAD DIED flag to prevent further wakeups of the
 646          * soon to be gone threaded handler.
 647          */
 648         set_bit(IRQTF_DIED, &tsk->irqaction->flags);
 649 }
 650
 651 /*
 652  * Internal function to register an irqaction - typically used to
 653  * allocate special interrupts that are part of the architecture.
 654  */
 655 static int
 656 __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
 657 {
 658         struct irqaction *old, **old_ptr;
 659         const char *old_name = NULL;
 660         unsigned long flags;
 661         int nested, shared = 0;
 662         int ret;
 663
 664         if (!desc)
 665                 return -EINVAL;
 666
 667         if (desc->irq_data.chip == &no_irq_chip)
 668                 return -ENOSYS;
 669         /*
 670          * Some drivers like serial.c use request_irq() heavily,
 671          * so we have to be careful not to interfere with a
 672          * running system.
 673          */
 674         if (new->flags & IRQF_SAMPLE_RANDOM) {
 675                 /*
 676                  * This function might sleep, we want to call it first,
 677                  * outside of the atomic block.
 678                  * Yes, this might clear the entropy pool if the wrong
 679                  * driver is attempted to be loaded, without actually
 680                  * installing a new handler, but is this really a problem,
 681                  * only the sysadmin is able to do this.
 682                  */
 683                 rand_initialize_irq(irq);
 684         }
 685
 686         /* Oneshot interrupts are not allowed with shared */
 687         if ((new->flags & IRQF_ONESHOT) && (new->flags & IRQF_SHARED))
 688                 return -EINVAL;
 689
 690         /*
 691          * Check whether the interrupt nests into another interrupt
 692          * thread.
 693          */
 694         nested = desc->status & IRQ_NESTED_THREAD;
 695         if (nested) {
 696                 if (!new->thread_fn)
 697                         return -EINVAL;
 698                 /*
 699                  * Replace the primary handler which was provided from
 700                  * the driver for non nested interrupt handling by the
 701                  * dummy function which warns when called.
 702                  */
 703                 new->handler = irq_nested_primary_handler;
 704         }
 705
 706         /*
 707          * Create a handler thread when a thread function is supplied
 708          * and the interrupt does not nest into another interrupt
 709          * thread.
 710          */
 711         if (new->thread_fn && !nested) {
 712                 struct task_struct *t;
 713
 714                 t = kthread_create(irq_thread, new, "irq/%d-%s", irq,
 715                                    new->name);
 716                 if (IS_ERR(t))
 717                         return PTR_ERR(t);
 718                 /*
 719                  * We keep the reference to the task struct even if
 720                  * the thread dies to avoid that the interrupt code
 721                  * references an already freed task_struct.
 722                  */
 723                 get_task_struct(t);
 724                 new->thread = t;
 725         }
 726
 727         /*
 728          * The following block of code has to be executed atomically
 729          */
 730         raw_spin_lock_irqsave(&desc->lock, flags);
 731         old_ptr = &desc->action;
 732         old = *old_ptr;
 733         if (old) {
 734                 /*
 735                  * Can't share interrupts unless both agree to and are
 736                  * the same type (level, edge, polarity). So both flag
 737                  * fields must have IRQF_SHARED set and the bits which
 738                  * set the trigger type must match.
 739                  */
 740                 if (!((old->flags & new->flags) & IRQF_SHARED) ||
 741                     ((old->flags ^ new->flags) & IRQF_TRIGGER_MASK)) {
 742                         old_name = old->name;
 743                         goto mismatch;
 744                 }
 745
 746 #if defined(CONFIG_IRQ_PER_CPU)
 747                 /* All handlers must agree on per-cpuness */
 748                 if ((old->flags & IRQF_PERCPU) !=
 749                     (new->flags & IRQF_PERCPU))
 750                         goto mismatch;
 751 #endif
 752
 753                 /* add new interrupt at end of irq queue */
 754                 do {
 755                         old_ptr = &old->next;
 756                         old = *old_ptr;
 757                 } while (old);
 758                 shared = 1;
 759         }
 760
 761         if (!shared) {
 762                 irq_chip_set_defaults(desc->irq_data.chip);
 763
 764                 init_waitqueue_head(&desc->wait_for_threads);
 765
 766                 /* Setup the type (level, edge polarity) if configured: */
 767                 if (new->flags & IRQF_TRIGGER_MASK) {
 768                         ret = __irq_set_trigger(desc, irq,
 769                                         new->flags & IRQF_TRIGGER_MASK);
 770
 771                         if (ret)
 772                                 goto out_thread;
 773                 } else
 774                         compat_irq_chip_set_default_handler(desc);
 775 #if defined(CONFIG_IRQ_PER_CPU)
 776                 if (new->flags & IRQF_PERCPU)
 777                         desc->status |= IRQ_PER_CPU;
 778 #endif
 779
 780                 desc->status &= ~(IRQ_AUTODETECT | IRQ_WAITING | IRQ_ONESHOT |
 781                                   IRQ_INPROGRESS | IRQ_SPURIOUS_DISABLED);
 782
 783                 if (new->flags & IRQF_ONESHOT)
 784                         desc->status |= IRQ_ONESHOT;
 785
 786                 if (!(desc->status & IRQ_NOAUTOEN)) {
 787                         desc->depth = 0;
 788                         desc->status &= ~IRQ_DISABLED;
 789                         desc->irq_data.chip->irq_startup(&desc->irq_data);
 790                 } else
 791                         /* Undo nested disables: */
 792                         desc->depth = 1;
 793
 794                 /* Exclude IRQ from balancing if requested */
 795                 if (new->flags & IRQF_NOBALANCING)
 796                         desc->status |= IRQ_NO_BALANCING;
 797
 798                 /* Set default affinity mask once everything is setup */
 799                 setup_affinity(irq, desc);
 800
 801         } else if ((new->flags & IRQF_TRIGGER_MASK)
 802                         && (new->flags & IRQF_TRIGGER_MASK)
 803                                 != (desc->status & IRQ_TYPE_SENSE_MASK)) {
 804                 /* hope the handler works with the actual trigger mode... */
 805                 pr_warning("IRQ %d uses trigger mode %d; requested %d\n",
 806                                 irq, (int)(desc->status & IRQ_TYPE_SENSE_MASK),
 807                                 (int)(new->flags & IRQF_TRIGGER_MASK));
 808         }
 809
 810         new->irq = irq;
 811         *old_ptr = new;
 812
 813         /* Reset broken irq detection when installing new handler */
 814         desc->irq_count = 0;
 815         desc->irqs_unhandled = 0;
 816
 817         /*
 818          * Check whether we disabled the irq via the spurious handler
 819          * before. Reenable it and give it another chance.
 820          */
 821         if (shared && (desc->status & IRQ_SPURIOUS_DISABLED)) {
 822                 desc->status &= ~IRQ_SPURIOUS_DISABLED;
 823                 __enable_irq(desc, irq, false);
 824         }
 825
 826         raw_spin_unlock_irqrestore(&desc->lock, flags);
 827
 828         /*
 829          * Strictly no need to wake it up, but hung_task complains
 830          * when no hard interrupt wakes the thread up.
 831          */
 832         if (new->thread)
 833                 wake_up_process(new->thread);
 834
 835         register_irq_proc(irq, desc);
 836         new->dir = NULL;
 837         register_handler_proc(irq, new);
 838
 839         return 0;
 840
 841 mismatch:
 842 #ifdef CONFIG_DEBUG_SHIRQ
 843         if (!(new->flags & IRQF_PROBE_SHARED)) {
 844                 printk(KERN_ERR "IRQ handler type mismatch for IRQ %d\n", irq);
 845                 if (old_name)
 846                         printk(KERN_ERR "current handler: %s\n", old_name);
 847                 dump_stack();
 848         }
 849 #endif
 850         ret = -EBUSY;
 851
 852 out_thread:
 853         raw_spin_unlock_irqrestore(&desc->lock, flags);
 854         if (new->thread) {
 855                 struct task_struct *t = new->thread;
 856
 857                 new->thread = NULL;
 858                 if (likely(!test_bit(IRQTF_DIED, &new->thread_flags)))
 859                         kthread_stop(t);
 860                 put_task_struct(t);
 861         }
 862         return ret;
 863 }
 864
 865 /**
 866  *      setup_irq - setup an interrupt
 867  *      @irq: Interrupt line to setup
 868  *      @act: irqaction for the interrupt
 869  *
 870  * Used to statically setup interrupts in the early boot process.
 871  */
 872 int setup_irq(unsigned int irq, struct irqaction *act)
 873 {
 874         struct irq_desc *desc = irq_to_desc(irq);
 875
 876         return __setup_irq(irq, desc, act);
 877 }
 878 EXPORT_SYMBOL_GPL(setup_irq);
 879
 880  /*
 881  * Internal function to unregister an irqaction - used to free
 882  * regular and special interrupts that are part of the architecture.
 883  */
 884 static struct irqaction *__free_irq(unsigned int irq, void *dev_id)
 885 {
 886         struct irq_desc *desc = irq_to_desc(irq);
 887         struct irqaction *action, **action_ptr;
 888         unsigned long flags;
 889
 890         WARN(in_interrupt(), "Trying to free IRQ %d from IRQ context!\n", irq);
 891
 892         if (!desc)
 893                 return NULL;
 894
 895         raw_spin_lock_irqsave(&desc->lock, flags);
 896
 897         /*
 898          * There can be multiple actions per IRQ descriptor, find the right
 899          * one based on the dev_id:
 900          */
 901         action_ptr = &desc->action;
 902         for (;;) {
 903                 action = *action_ptr;
 904
 905                 if (!action) {
 906                         WARN(1, "Trying to free already-free IRQ %d\n", irq);
 907                         raw_spin_unlock_irqrestore(&desc->lock, flags);
 908
 909                         return NULL;
 910                 }
 911
 912                 if (action->dev_id == dev_id)
 913                         break;
 914                 action_ptr = &action->next;
 915         }
 916
 917         /* Found it - now remove it from the list of entries: */
 918         *action_ptr = action->next;
 919
 920         /* Currently used only by UML, might disappear one day: */
 921 #ifdef CONFIG_IRQ_RELEASE_METHOD
 922         if (desc->irq_data.chip->release)
 923                 desc->irq_data.chip->release(irq, dev_id);
 924 #endif
 925
 926         /* If this was the last handler, shut down the IRQ line: */
 927         if (!desc->action) {
 928                 desc->status |= IRQ_DISABLED;
 929                 if (desc->irq_data.chip->irq_shutdown)
 930                         desc->irq_data.chip->irq_shutdown(&desc->irq_data);
 931                 else
 932                         desc->irq_data.chip->irq_disable(&desc->irq_data);
 933         }
 934
 935 #ifdef CONFIG_SMP
 936         /* make sure affinity_hint is cleaned up */
 937         if (WARN_ON_ONCE(desc->affinity_hint))
 938                 desc->affinity_hint = NULL;
 939 #endif
 940
 941         raw_spin_unlock_irqrestore(&desc->lock, flags);
 942
 943         unregister_handler_proc(irq, action);
 944
 945         /* Make sure it's not being used on another CPU: */
 946         synchronize_irq(irq);
 947
 948 #ifdef CONFIG_DEBUG_SHIRQ
 949         /*
 950          * It's a shared IRQ -- the driver ought to be prepared for an IRQ
 951          * event to happen even now it's being freed, so let's make sure that
 952          * is so by doing an extra call to the handler ....
 953          *
 954          * ( We do this after actually deregistering it, to make sure that a
 955          *   'real' IRQ doesn't run in * parallel with our fake. )
 956          */
 957         if (action->flags & IRQF_SHARED) {
 958                 local_irq_save(flags);
 959                 action->handler(irq, dev_id);
 960                 local_irq_restore(flags);
 961         }
 962 #endif
 963
 964         if (action->thread) {
 965                 if (!test_bit(IRQTF_DIED, &action->thread_flags))
 966                         kthread_stop(action->thread);
 967                 put_task_struct(action->thread);
 968         }
 969
 970         return action;
 971 }
 972
 973 /**
 974  *      remove_irq - free an interrupt
 975  *      @irq: Interrupt line to free
 976  *      @act: irqaction for the interrupt
 977  *
 978  * Used to remove interrupts statically setup by the early boot process.
 979  */
 980 void remove_irq(unsigned int irq, struct irqaction *act)
 981 {
 982         __free_irq(irq, act->dev_id);
 983 }
 984 EXPORT_SYMBOL_GPL(remove_irq);
 985
 986 /**
 987  *      free_irq - free an interrupt allocated with request_irq
 988  *      @irq: Interrupt line to free
 989  *      @dev_id: Device identity to free
 990  *
 991  *      Remove an interrupt handler. The handler is removed and if the
 992  *      interrupt line is no longer in use by any driver it is disabled.
 993  *      On a shared IRQ the caller must ensure the interrupt is disabled
 994  *      on the card it drives before calling this function. The function
 995  *      does not return until any executing interrupts for this IRQ
 996  *      have completed.
 997  *
 998  *      This function must not be called from interrupt context.
 999  */
1000 void free_irq(unsigned int irq, void *dev_id)
1001 {
1002         struct irq_desc *desc = irq_to_desc(irq);
1003
1004         if (!desc)
1005                 return;
1006
1007         chip_bus_lock(desc);
1008         kfree(__free_irq(irq, dev_id));
1009         chip_bus_sync_unlock(desc);
1010 }
1011 EXPORT_SYMBOL(free_irq);
1012
1013 /**
1014  *      request_threaded_irq - allocate an interrupt line
1015  *      @irq: Interrupt line to allocate
1016  *      @handler: Function to be called when the IRQ occurs.
1017  *                Primary handler for threaded interrupts
1018  *                If NULL and thread_fn != NULL the default
1019  *                primary handler is installed
1020  *      @thread_fn: Function called from the irq handler thread
1021  *                  If NULL, no irq thread is created
1022  *      @irqflags: Interrupt type flags
1023  *      @devname: An ascii name for the claiming device
1024  *      @dev_id: A cookie passed back to the handler function
1025  *
1026  *      This call allocates interrupt resources and enables the
1027  *      interrupt line and IRQ handling. From the point this
1028  *      call is made your handler function may be invoked. Since
1029  *      your handler function must clear any interrupt the board
1030  *      raises, you must take care both to initialise your hardware
1031  *      and to set up the interrupt handler in the right order.
1032  *
1033  *      If you want to set up a threaded irq handler for your device
1034  *      then you need to supply @handler and @thread_fn. @handler ist
1035  *      still called in hard interrupt context and has to check
1036  *      whether the interrupt originates from the device. If yes it
1037  *      needs to disable the interrupt on the device and return
1038  *      IRQ_WAKE_THREAD which will wake up the handler thread and run
1039  *      @thread_fn. This split handler design is necessary to support
1040  *      shared interrupts.
1041  *
1042  *      Dev_id must be globally unique. Normally the address of the
1043  *      device data structure is used as the cookie. Since the handler
1044  *      receives this value it makes sense to use it.
1045  *
1046  *      If your interrupt is shared you must pass a non NULL dev_id
1047  *      as this is required when freeing the interrupt.
1048  *
1049  *      Flags:
1050  *
1051  *      IRQF_SHARED             Interrupt is shared
1052  *      IRQF_SAMPLE_RANDOM      The interrupt can be used for entropy
1053  *      IRQF_TRIGGER_*          Specify active edge(s) or level
1054  *
1055  */
1056 int request_threaded_irq(unsigned int irq, irq_handler_t handler,
1057                          irq_handler_t thread_fn, unsigned long irqflags,
1058                          const char *devname, void *dev_id)
1059 {
1060         struct irqaction *action;
1061         struct irq_desc *desc;
1062         int retval;
1063
1064         /*
1065          * Sanity-check: shared interrupts must pass in a real dev-ID,
1066          * otherwise we'll have trouble later trying to figure out
1067          * which interrupt is which (messes up the interrupt freeing
1068          * logic etc).
1069          */
1070         if ((irqflags & IRQF_SHARED) && !dev_id)
1071                 return -EINVAL;
1072
1073         desc = irq_to_desc(irq);
1074         if (!desc)
1075                 return -EINVAL;
1076
1077         if (desc->status & IRQ_NOREQUEST)
1078                 return -EINVAL;
1079
1080         if (!handler) {
1081                 if (!thread_fn)
1082                         return -EINVAL;
1083                 handler = irq_default_primary_handler;
1084         }
1085
1086         action = kzalloc(sizeof(struct irqaction), GFP_KERNEL);
1087         if (!action)
1088                 return -ENOMEM;
1089
1090         action->handler = handler;
1091         action->thread_fn = thread_fn;
1092         action->flags = irqflags;
1093         action->name = devname;
1094         action->dev_id = dev_id;
1095
1096         chip_bus_lock(desc);
1097         retval = __setup_irq(irq, desc, action);
1098         chip_bus_sync_unlock(desc);
1099
1100         if (retval)
1101                 kfree(action);
1102
1103 #ifdef CONFIG_DEBUG_SHIRQ
1104         if (!retval && (irqflags & IRQF_SHARED)) {
1105                 /*
1106                  * It's a shared IRQ -- the driver ought to be prepared for it
1107                  * to happen immediately, so let's make sure....
1108                  * We disable the irq to make sure that a 'real' IRQ doesn't
1109                  * run in parallel with our fake.
1110                  */
1111                 unsigned long flags;
1112
1113                 disable_irq(irq);
1114                 local_irq_save(flags);
1115
1116                 handler(irq, dev_id);
1117
1118                 local_irq_restore(flags);
1119                 enable_irq(irq);
1120         }
1121 #endif
1122         return retval;
1123 }
1124 EXPORT_SYMBOL(request_threaded_irq);
1125
1126 /**
1127  *      request_any_context_irq - allocate an interrupt line
1128  *      @irq: Interrupt line to allocate
1129  *      @handler: Function to be called when the IRQ occurs.
1130  *                Threaded handler for threaded interrupts.
1131  *      @flags: Interrupt type flags
1132  *      @name: An ascii name for the claiming device
1133  *      @dev_id: A cookie passed back to the handler function
1134  *
1135  *      This call allocates interrupt resources and enables the
1136  *      interrupt line and IRQ handling. It selects either a
1137  *      hardirq or threaded handling method depending on the
1138  *      context.
1139  *
1140  *      On failure, it returns a negative value. On success,
1141  *      it returns either IRQC_IS_HARDIRQ or IRQC_IS_NESTED.
1142  */
1143 int request_any_context_irq(unsigned int irq, irq_handler_t handler,
1144                             unsigned long flags, const char *name, void *dev_id)
1145 {
1146         struct irq_desc *desc = irq_to_desc(irq);
1147         int ret;
1148
1149         if (!desc)
1150                 return -EINVAL;
1151
1152         if (desc->status & IRQ_NESTED_THREAD) {
1153                 ret = request_threaded_irq(irq, NULL, handler,
1154                                            flags, name, dev_id);
1155                 return !ret ? IRQC_IS_NESTED : ret;
1156         }
1157
1158         ret = request_irq(irq, handler, flags, name, dev_id);
1159         return !ret ? IRQC_IS_HARDIRQ : ret;
1160 }
1161 EXPORT_SYMBOL_GPL(request_any_context_irq);