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 #ifdef CONFIG_IRQ_FORCED_THREADING
  21 __read_mostly bool force_irqthreads;
  22
  23 static int __init setup_forced_irqthreads(char *arg)
  24 {
  25         force_irqthreads = true;
  26         return 0;
  27 }
  28 early_param("threadirqs", setup_forced_irqthreads);
  29 #endif
  30
  31 /**
  32  *      synchronize_irq - wait for pending IRQ handlers (on other CPUs)
  33  *      @irq: interrupt number to wait for
  34  *
  35  *      This function waits for any pending IRQ handlers for this interrupt
  36  *      to complete before returning. If you use this function while
  37  *      holding a resource the IRQ handler may need you will deadlock.
  38  *
  39  *      This function may be called - with care - from IRQ context.
  40  */
  41 void synchronize_irq(unsigned int irq)
  42 {
  43         struct irq_desc *desc = irq_to_desc(irq);
  44         bool inprogress;
  45
  46         if (!desc)
  47                 return;
  48
  49         do {
  50                 unsigned long flags;
  51
  52                 /*
  53                  * Wait until we're out of the critical section.  This might
  54                  * give the wrong answer due to the lack of memory barriers.
  55                  */
  56                 while (irqd_irq_inprogress(&desc->irq_data))
  57                         cpu_relax();
  58
  59                 /* Ok, that indicated we're done: double-check carefully. */
  60                 raw_spin_lock_irqsave(&desc->lock, flags);
  61                 inprogress = irqd_irq_inprogress(&desc->irq_data);
  62                 raw_spin_unlock_irqrestore(&desc->lock, flags);
  63
  64                 /* Oops, that failed? */
  65         } while (inprogress);
  66
  67         /*
  68          * We made sure that no hardirq handler is running. Now verify
  69          * that no threaded handlers are active.
  70          */
  71         wait_event(desc->wait_for_threads, !atomic_read(&desc->threads_active));
  72 }
  73 EXPORT_SYMBOL(synchronize_irq);
  74
  75 #ifdef CONFIG_SMP
  76 cpumask_var_t irq_default_affinity;
  77
  78 /**
  79  *      irq_can_set_affinity - Check if the affinity of a given irq can be set
  80  *      @irq:           Interrupt to check
  81  *
  82  */
  83 int irq_can_set_affinity(unsigned int irq)
  84 {
  85         struct irq_desc *desc = irq_to_desc(irq);
  86
  87         if (!desc || !irqd_can_balance(&desc->irq_data) ||
  88             !desc->irq_data.chip || !desc->irq_data.chip->irq_set_affinity)
  89                 return 0;
  90
  91         return 1;
  92 }
  93
  94 /**
  95  *      irq_set_thread_affinity - Notify irq threads to adjust affinity
  96  *      @desc:          irq descriptor which has affitnity changed
  97  *
  98  *      We just set IRQTF_AFFINITY and delegate the affinity setting
  99  *      to the interrupt thread itself. We can not call
 100  *      set_cpus_allowed_ptr() here as we hold desc->lock and this
 101  *      code can be called from hard interrupt context.
 102  */
 103 void irq_set_thread_affinity(struct irq_desc *desc)
 104 {
 105         struct irqaction *action = desc->action;
 106
 107         while (action) {
 108                 if (action->thread)
 109                         set_bit(IRQTF_AFFINITY, &action->thread_flags);
 110                 action = action->next;
 111         }
 112 }
 113
 114 #ifdef CONFIG_GENERIC_PENDING_IRQ
 115 static inline bool irq_can_move_pcntxt(struct irq_data *data)
 116 {
 117         return irqd_can_move_in_process_context(data);
 118 }
 119 static inline bool irq_move_pending(struct irq_data *data)
 120 {
 121         return irqd_is_setaffinity_pending(data);
 122 }
 123 static inline void
 124 irq_copy_pending(struct irq_desc *desc, const struct cpumask *mask)
 125 {
 126         cpumask_copy(desc->pending_mask, mask);
 127 }
 128 static inline void
 129 irq_get_pending(struct cpumask *mask, struct irq_desc *desc)
 130 {
 131         cpumask_copy(mask, desc->pending_mask);
 132 }
 133 #else
 134 static inline bool irq_can_move_pcntxt(struct irq_data *data) { return true; }
 135 static inline bool irq_move_pending(struct irq_data *data) { return false; }
 136 static inline void
 137 irq_copy_pending(struct irq_desc *desc, const struct cpumask *mask) { }
 138 static inline void
 139 irq_get_pending(struct cpumask *mask, struct irq_desc *desc) { }
 140 #endif
 141
 142 int __irq_set_affinity_locked(struct irq_data *data, const struct cpumask *mask)
 143 {
 144         struct irq_chip *chip = irq_data_get_irq_chip(data);
 145         struct irq_desc *desc = irq_data_to_desc(data);
 146         int ret = 0;
 147
 148         if (!chip || !chip->irq_set_affinity)
 149                 return -EINVAL;
 150
 151         if (irq_can_move_pcntxt(data)) {
 152                 ret = chip->irq_set_affinity(data, mask, false);
 153                 switch (ret) {
 154                 case IRQ_SET_MASK_OK:
 155                         cpumask_copy(data->affinity, mask);
 156                 case IRQ_SET_MASK_OK_NOCOPY:
 157                         irq_set_thread_affinity(desc);
 158                         ret = 0;
 159                 }
 160         } else {
 161                 irqd_set_move_pending(data);
 162                 irq_copy_pending(desc, mask);
 163         }
 164
 165         if (desc->affinity_notify) {
 166                 kref_get(&desc->affinity_notify->kref);
 167                 schedule_work(&desc->affinity_notify->work);
 168         }
 169         irqd_set(data, IRQD_AFFINITY_SET);
 170
 171         return ret;
 172 }
 173
 174 /**
 175  *      irq_set_affinity - Set the irq affinity of a given irq
 176  *      @irq:           Interrupt to set affinity
 177  *      @mask:          cpumask
 178  *
 179  */
 180 int irq_set_affinity(unsigned int irq, const struct cpumask *mask)
 181 {
 182         struct irq_desc *desc = irq_to_desc(irq);
 183         unsigned long flags;
 184         int ret;
 185
 186         if (!desc)
 187                 return -EINVAL;
 188
 189         raw_spin_lock_irqsave(&desc->lock, flags);
 190         ret =  __irq_set_affinity_locked(irq_desc_get_irq_data(desc), mask);
 191         raw_spin_unlock_irqrestore(&desc->lock, flags);
 192         return ret;
 193 }
 194
 195 int irq_set_affinity_hint(unsigned int irq, const struct cpumask *m)
 196 {
 197         unsigned long flags;
 198         struct irq_desc *desc = irq_get_desc_lock(irq, &flags, IRQ_GET_DESC_CHECK_GLOBAL);
 199
 200         if (!desc)
 201                 return -EINVAL;
 202         desc->affinity_hint = m;
 203         irq_put_desc_unlock(desc, flags);
 204         return 0;
 205 }
 206 EXPORT_SYMBOL_GPL(irq_set_affinity_hint);
 207
 208 static void irq_affinity_notify(struct work_struct *work)
 209 {
 210         struct irq_affinity_notify *notify =
 211                 container_of(work, struct irq_affinity_notify, work);
 212         struct irq_desc *desc = irq_to_desc(notify->irq);
 213         cpumask_var_t cpumask;
 214         unsigned long flags;
 215
 216         if (!desc || !alloc_cpumask_var(&cpumask, GFP_KERNEL))
 217                 goto out;
 218
 219         raw_spin_lock_irqsave(&desc->lock, flags);
 220         if (irq_move_pending(&desc->irq_data))
 221                 irq_get_pending(cpumask, desc);
 222         else
 223                 cpumask_copy(cpumask, desc->irq_data.affinity);
 224         raw_spin_unlock_irqrestore(&desc->lock, flags);
 225
 226         notify->notify(notify, cpumask);
 227
 228         free_cpumask_var(cpumask);
 229 out:
 230         kref_put(&notify->kref, notify->release);
 231 }
 232
 233 /**
 234  *      irq_set_affinity_notifier - control notification of IRQ affinity changes
 235  *      @irq:           Interrupt for which to enable/disable notification
 236  *      @notify:        Context for notification, or %NULL to disable
 237  *                      notification.  Function pointers must be initialised;
 238  *                      the other fields will be initialised by this function.
 239  *
 240  *      Must be called in process context.  Notification may only be enabled
 241  *      after the IRQ is allocated and must be disabled before the IRQ is
 242  *      freed using free_irq().
 243  */
 244 int
 245 irq_set_affinity_notifier(unsigned int irq, struct irq_affinity_notify *notify)
 246 {
 247         struct irq_desc *desc = irq_to_desc(irq);
 248         struct irq_affinity_notify *old_notify;
 249         unsigned long flags;
 250
 251         /* The release function is promised process context */
 252         might_sleep();
 253
 254         if (!desc)
 255                 return -EINVAL;
 256
 257         /* Complete initialisation of *notify */
 258         if (notify) {
 259                 notify->irq = irq;
 260                 kref_init(&notify->kref);
 261                 INIT_WORK(&notify->work, irq_affinity_notify);
 262         }
 263
 264         raw_spin_lock_irqsave(&desc->lock, flags);
 265         old_notify = desc->affinity_notify;
 266         desc->affinity_notify = notify;
 267         raw_spin_unlock_irqrestore(&desc->lock, flags);
 268
 269         if (old_notify)
 270                 kref_put(&old_notify->kref, old_notify->release);
 271
 272         return 0;
 273 }
 274 EXPORT_SYMBOL_GPL(irq_set_affinity_notifier);
 275
 276 #ifndef CONFIG_AUTO_IRQ_AFFINITY
 277 /*
 278  * Generic version of the affinity autoselector.
 279  */
 280 static int
 281 setup_affinity(unsigned int irq, struct irq_desc *desc, struct cpumask *mask)
 282 {
 283         struct irq_chip *chip = irq_desc_get_chip(desc);
 284         struct cpumask *set = irq_default_affinity;
 285         int ret, node = desc->irq_data.node;
 286
 287         /* Excludes PER_CPU and NO_BALANCE interrupts */
 288         if (!irq_can_set_affinity(irq))
 289                 return 0;
 290
 291         /*
 292          * Preserve an userspace affinity setup, but make sure that
 293          * one of the targets is online.
 294          */
 295         if (irqd_has_set(&desc->irq_data, IRQD_AFFINITY_SET)) {
 296                 if (cpumask_intersects(desc->irq_data.affinity,
 297                                        cpu_online_mask))
 298                         set = desc->irq_data.affinity;
 299                 else
 300                         irqd_clear(&desc->irq_data, IRQD_AFFINITY_SET);
 301         }
 302
 303         cpumask_and(mask, cpu_online_mask, set);
 304         if (node != NUMA_NO_NODE) {
 305                 const struct cpumask *nodemask = cpumask_of_node(node);
 306
 307                 /* make sure at least one of the cpus in nodemask is online */
 308                 if (cpumask_intersects(mask, nodemask))
 309                         cpumask_and(mask, mask, nodemask);
 310         }
 311         ret = chip->irq_set_affinity(&desc->irq_data, mask, false);
 312         switch (ret) {
 313         case IRQ_SET_MASK_OK:
 314                 cpumask_copy(desc->irq_data.affinity, mask);
 315         case IRQ_SET_MASK_OK_NOCOPY:
 316                 irq_set_thread_affinity(desc);
 317         }
 318         return 0;
 319 }
 320 #else
 321 static inline int
 322 setup_affinity(unsigned int irq, struct irq_desc *d, struct cpumask *mask)
 323 {
 324         return irq_select_affinity(irq);
 325 }
 326 #endif
 327
 328 /*
 329  * Called when affinity is set via /proc/irq
 330  */
 331 int irq_select_affinity_usr(unsigned int irq, struct cpumask *mask)
 332 {
 333         struct irq_desc *desc = irq_to_desc(irq);
 334         unsigned long flags;
 335         int ret;
 336
 337         raw_spin_lock_irqsave(&desc->lock, flags);
 338         ret = setup_affinity(irq, desc, mask);
 339         raw_spin_unlock_irqrestore(&desc->lock, flags);
 340         return ret;
 341 }
 342
 343 #else
 344 static inline int
 345 setup_affinity(unsigned int irq, struct irq_desc *desc, struct cpumask *mask)
 346 {
 347         return 0;
 348 }
 349 #endif
 350
 351 void __disable_irq(struct irq_desc *desc, unsigned int irq, bool suspend)
 352 {
 353         if (suspend) {
 354                 if (!desc->action || (desc->action->flags & IRQF_NO_SUSPEND))
 355                         return;
 356                 desc->istate |= IRQS_SUSPENDED;
 357         }
 358
 359         if (!desc->depth++)
 360                 irq_disable(desc);
 361 }
 362
 363 static int __disable_irq_nosync(unsigned int irq)
 364 {
 365         unsigned long flags;
 366         struct irq_desc *desc = irq_get_desc_buslock(irq, &flags, IRQ_GET_DESC_CHECK_GLOBAL);
 367
 368         if (!desc)
 369                 return -EINVAL;
 370         __disable_irq(desc, irq, false);
 371         irq_put_desc_busunlock(desc, flags);
 372         return 0;
 373 }
 374
 375 /**
 376  *      disable_irq_nosync - disable an irq without waiting
 377  *      @irq: Interrupt to disable
 378  *
 379  *      Disable the selected interrupt line.  Disables and Enables are
 380  *      nested.
 381  *      Unlike disable_irq(), this function does not ensure existing
 382  *      instances of the IRQ handler have completed before returning.
 383  *
 384  *      This function may be called from IRQ context.
 385  */
 386 void disable_irq_nosync(unsigned int irq)
 387 {
 388         __disable_irq_nosync(irq);
 389 }
 390 EXPORT_SYMBOL(disable_irq_nosync);
 391
 392 /**
 393  *      disable_irq - disable an irq and wait for completion
 394  *      @irq: Interrupt to disable
 395  *
 396  *      Disable the selected interrupt line.  Enables and Disables are
 397  *      nested.
 398  *      This function waits for any pending IRQ handlers for this interrupt
 399  *      to complete before returning. If you use this function while
 400  *      holding a resource the IRQ handler may need you will deadlock.
 401  *
 402  *      This function may be called - with care - from IRQ context.
 403  */
 404 void disable_irq(unsigned int irq)
 405 {
 406         if (!__disable_irq_nosync(irq))
 407                 synchronize_irq(irq);
 408 }
 409 EXPORT_SYMBOL(disable_irq);
 410
 411 void __enable_irq(struct irq_desc *desc, unsigned int irq, bool resume)
 412 {
 413         if (resume) {
 414                 if (!(desc->istate & IRQS_SUSPENDED)) {
 415                         if (!desc->action)
 416                                 return;
 417                         if (!(desc->action->flags & IRQF_FORCE_RESUME))
 418                                 return;
 419                         /* Pretend that it got disabled ! */
 420                         desc->depth++;
 421                 }
 422                 desc->istate &= ~IRQS_SUSPENDED;
 423         }
 424
 425         switch (desc->depth) {
 426         case 0:
 427  err_out:
 428                 WARN(1, KERN_WARNING "Unbalanced enable for IRQ %d\n", irq);
 429                 break;
 430         case 1: {
 431                 if (desc->istate & IRQS_SUSPENDED)
 432                         goto err_out;
 433                 /* Prevent probing on this irq: */
 434                 irq_settings_set_noprobe(desc);
 435                 irq_enable(desc);
 436                 check_irq_resend(desc, irq);
 437                 /* fall-through */
 438         }
 439         default:
 440                 desc->depth--;
 441         }
 442 }
 443
 444 /**
 445  *      enable_irq - enable handling of an irq
 446  *      @irq: Interrupt to enable
 447  *
 448  *      Undoes the effect of one call to disable_irq().  If this
 449  *      matches the last disable, processing of interrupts on this
 450  *      IRQ line is re-enabled.
 451  *
 452  *      This function may be called from IRQ context only when
 453  *      desc->irq_data.chip->bus_lock and desc->chip->bus_sync_unlock are NULL !
 454  */
 455 void enable_irq(unsigned int irq)
 456 {
 457         unsigned long flags;
 458         struct irq_desc *desc = irq_get_desc_buslock(irq, &flags, IRQ_GET_DESC_CHECK_GLOBAL);
 459
 460         if (!desc)
 461                 return;
 462         if (WARN(!desc->irq_data.chip,
 463                  KERN_ERR "enable_irq before setup/request_irq: irq %u\n", irq))
 464                 goto out;
 465
 466         __enable_irq(desc, irq, false);
 467 out:
 468         irq_put_desc_busunlock(desc, flags);
 469 }
 470 EXPORT_SYMBOL(enable_irq);
 471
 472 static int set_irq_wake_real(unsigned int irq, unsigned int on)
 473 {
 474         struct irq_desc *desc = irq_to_desc(irq);
 475         int ret = -ENXIO;
 476
 477         if (irq_desc_get_chip(desc)->flags &  IRQCHIP_SKIP_SET_WAKE)
 478                 return 0;
 479
 480         if (desc->irq_data.chip->irq_set_wake)
 481                 ret = desc->irq_data.chip->irq_set_wake(&desc->irq_data, on);
 482
 483         return ret;
 484 }
 485
 486 /**
 487  *      irq_set_irq_wake - control irq power management wakeup
 488  *      @irq:   interrupt to control
 489  *      @on:    enable/disable power management wakeup
 490  *
 491  *      Enable/disable power management wakeup mode, which is
 492  *      disabled by default.  Enables and disables must match,
 493  *      just as they match for non-wakeup mode support.
 494  *
 495  *      Wakeup mode lets this IRQ wake the system from sleep
 496  *      states like "suspend to RAM".
 497  */
 498 int irq_set_irq_wake(unsigned int irq, unsigned int on)
 499 {
 500         unsigned long flags;
 501         struct irq_desc *desc = irq_get_desc_buslock(irq, &flags, IRQ_GET_DESC_CHECK_GLOBAL);
 502         int ret = 0;
 503
 504         if (!desc)
 505                 return -EINVAL;
 506
 507         /* wakeup-capable irqs can be shared between drivers that
 508          * don't need to have the same sleep mode behaviors.
 509          */
 510         if (on) {
 511                 if (desc->wake_depth++ == 0) {
 512                         ret = set_irq_wake_real(irq, on);
 513                         if (ret)
 514                                 desc->wake_depth = 0;
 515                         else
 516                                 irqd_set(&desc->irq_data, IRQD_WAKEUP_STATE);
 517                 }
 518         } else {
 519                 if (desc->wake_depth == 0) {
 520                         WARN(1, "Unbalanced IRQ %d wake disable\n", irq);
 521                 } else if (--desc->wake_depth == 0) {
 522                         ret = set_irq_wake_real(irq, on);
 523                         if (ret)
 524                                 desc->wake_depth = 1;
 525                         else
 526                                 irqd_clear(&desc->irq_data, IRQD_WAKEUP_STATE);
 527                 }
 528         }
 529         irq_put_desc_busunlock(desc, flags);
 530         return ret;
 531 }
 532 EXPORT_SYMBOL(irq_set_irq_wake);
 533
 534 /*
 535  * Internal function that tells the architecture code whether a
 536  * particular irq has been exclusively allocated or is available
 537  * for driver use.
 538  */
 539 int can_request_irq(unsigned int irq, unsigned long irqflags)
 540 {
 541         unsigned long flags;
 542         struct irq_desc *desc = irq_get_desc_lock(irq, &flags, 0);
 543         int canrequest = 0;
 544
 545         if (!desc)
 546                 return 0;
 547
 548         if (irq_settings_can_request(desc)) {
 549                 if (desc->action)
 550                         if (irqflags & desc->action->flags & IRQF_SHARED)
 551                                 canrequest =1;
 552         }
 553         irq_put_desc_unlock(desc, flags);
 554         return canrequest;
 555 }
 556
 557 int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
 558                       unsigned long flags)
 559 {
 560         struct irq_chip *chip = desc->irq_data.chip;
 561         int ret, unmask = 0;
 562
 563         if (!chip || !chip->irq_set_type) {
 564                 /*
 565                  * IRQF_TRIGGER_* but the PIC does not support multiple
 566                  * flow-types?
 567                  */
 568                 pr_debug("genirq: No set_type function for IRQ %d (%s)\n", irq,
 569                          chip ? (chip->name ? : "unknown") : "unknown");
 570                 return 0;
 571         }
 572
 573         flags &= IRQ_TYPE_SENSE_MASK;
 574
 575         if (chip->flags & IRQCHIP_SET_TYPE_MASKED) {
 576                 if (!irqd_irq_masked(&desc->irq_data))
 577                         mask_irq(desc);
 578                 if (!irqd_irq_disabled(&desc->irq_data))
 579                         unmask = 1;
 580         }
 581
 582         /* caller masked out all except trigger mode flags */
 583         ret = chip->irq_set_type(&desc->irq_data, flags);
 584
 585         switch (ret) {
 586         case IRQ_SET_MASK_OK:
 587                 irqd_clear(&desc->irq_data, IRQD_TRIGGER_MASK);
 588                 irqd_set(&desc->irq_data, flags);
 589
 590         case IRQ_SET_MASK_OK_NOCOPY:
 591                 flags = irqd_get_trigger_type(&desc->irq_data);
 592                 irq_settings_set_trigger_mask(desc, flags);
 593                 irqd_clear(&desc->irq_data, IRQD_LEVEL);
 594                 irq_settings_clr_level(desc);
 595                 if (flags & IRQ_TYPE_LEVEL_MASK) {
 596                         irq_settings_set_level(desc);
 597                         irqd_set(&desc->irq_data, IRQD_LEVEL);
 598                 }
 599
 600                 ret = 0;
 601                 break;
 602         default:
 603                 pr_err("genirq: Setting trigger mode %lu for irq %u failed (%pF)\n",
 604                        flags, irq, chip->irq_set_type);
 605         }
 606         if (unmask)
 607                 unmask_irq(desc);
 608         return ret;
 609 }
 610
 611 /*
 612  * Default primary interrupt handler for threaded interrupts. Is
 613  * assigned as primary handler when request_threaded_irq is called
 614  * with handler == NULL. Useful for oneshot interrupts.
 615  */
 616 static irqreturn_t irq_default_primary_handler(int irq, void *dev_id)
 617 {
 618         return IRQ_WAKE_THREAD;
 619 }
 620
 621 /*
 622  * Primary handler for nested threaded interrupts. Should never be
 623  * called.
 624  */
 625 static irqreturn_t irq_nested_primary_handler(int irq, void *dev_id)
 626 {
 627         WARN(1, "Primary handler called for nested irq %d\n", irq);
 628         return IRQ_NONE;
 629 }
 630
 631 static int irq_wait_for_interrupt(struct irqaction *action)
 632 {
 633         set_current_state(TASK_INTERRUPTIBLE);
 634
 635         while (!kthread_should_stop()) {
 636
 637                 if (test_and_clear_bit(IRQTF_RUNTHREAD,
 638                                        &action->thread_flags)) {
 639                         __set_current_state(TASK_RUNNING);
 640                         return 0;
 641                 }
 642                 schedule();
 643                 set_current_state(TASK_INTERRUPTIBLE);
 644         }
 645         __set_current_state(TASK_RUNNING);
 646         return -1;
 647 }
 648
 649 /*
 650  * Oneshot interrupts keep the irq line masked until the threaded
 651  * handler finished. unmask if the interrupt has not been disabled and
 652  * is marked MASKED.
 653  */
 654 static void irq_finalize_oneshot(struct irq_desc *desc,
 655                                  struct irqaction *action)
 656 {
 657         if (!(desc->istate & IRQS_ONESHOT))
 658                 return;
 659 again:
 660         chip_bus_lock(desc);
 661         raw_spin_lock_irq(&desc->lock);
 662
 663         /*
 664          * Implausible though it may be we need to protect us against
 665          * the following scenario:
 666          *
 667          * The thread is faster done than the hard interrupt handler
 668          * on the other CPU. If we unmask the irq line then the
 669          * interrupt can come in again and masks the line, leaves due
 670          * to IRQS_INPROGRESS and the irq line is masked forever.
 671          *
 672          * This also serializes the state of shared oneshot handlers
 673          * versus "desc->threads_onehsot |= action->thread_mask;" in
 674          * irq_wake_thread(). See the comment there which explains the
 675          * serialization.
 676          */
 677         if (unlikely(irqd_irq_inprogress(&desc->irq_data))) {
 678                 raw_spin_unlock_irq(&desc->lock);
 679                 chip_bus_sync_unlock(desc);
 680                 cpu_relax();
 681                 goto again;
 682         }
 683
 684         /*
 685          * Now check again, whether the thread should run. Otherwise
 686          * we would clear the threads_oneshot bit of this thread which
 687          * was just set.
 688          */
 689         if (test_bit(IRQTF_RUNTHREAD, &action->thread_flags))
 690                 goto out_unlock;
 691
 692         desc->threads_oneshot &= ~action->thread_mask;
 693
 694         if (!desc->threads_oneshot && !irqd_irq_disabled(&desc->irq_data) &&
 695             irqd_irq_masked(&desc->irq_data))
 696                 unmask_irq(desc);
 697
 698 out_unlock:
 699         raw_spin_unlock_irq(&desc->lock);
 700         chip_bus_sync_unlock(desc);
 701 }
 702
 703 #ifdef CONFIG_SMP
 704 /*
 705  * Check whether we need to chasnge the affinity of the interrupt thread.
 706  */
 707 static void
 708 irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action)
 709 {
 710         cpumask_var_t mask;
 711
 712         if (!test_and_clear_bit(IRQTF_AFFINITY, &action->thread_flags))
 713                 return;
 714
 715         /*
 716          * In case we are out of memory we set IRQTF_AFFINITY again and
 717          * try again next time
 718          */
 719         if (!alloc_cpumask_var(&mask, GFP_KERNEL)) {
 720                 set_bit(IRQTF_AFFINITY, &action->thread_flags);
 721                 return;
 722         }
 723
 724         raw_spin_lock_irq(&desc->lock);
 725         cpumask_copy(mask, desc->irq_data.affinity);
 726         raw_spin_unlock_irq(&desc->lock);
 727
 728         set_cpus_allowed_ptr(current, mask);
 729         free_cpumask_var(mask);
 730 }
 731 #else
 732 static inline void
 733 irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action) { }
 734 #endif
 735
 736 /*
 737  * Interrupts which are not explicitely requested as threaded
 738  * interrupts rely on the implicit bh/preempt disable of the hard irq
 739  * context. So we need to disable bh here to avoid deadlocks and other
 740  * side effects.
 741  */
 742 static irqreturn_t
 743 irq_forced_thread_fn(struct irq_desc *desc, struct irqaction *action)
 744 {
 745         irqreturn_t ret;
 746
 747         local_bh_disable();
 748         ret = action->thread_fn(action->irq, action->dev_id);
 749         irq_finalize_oneshot(desc, action);
 750         local_bh_enable();
 751         return ret;
 752 }
 753
 754 /*
 755  * Interrupts explicitely requested as threaded interupts want to be
 756  * preemtible - many of them need to sleep and wait for slow busses to
 757  * complete.
 758  */
 759 static irqreturn_t irq_thread_fn(struct irq_desc *desc,
 760                 struct irqaction *action)
 761 {
 762         irqreturn_t ret;
 763
 764         ret = action->thread_fn(action->irq, action->dev_id);
 765         irq_finalize_oneshot(desc, action);
 766         return ret;
 767 }
 768
 769 static void wake_threads_waitq(struct irq_desc *desc)
 770 {
 771         if (atomic_dec_and_test(&desc->threads_active) &&
 772             waitqueue_active(&desc->wait_for_threads))
 773                 wake_up(&desc->wait_for_threads);
 774 }
 775
 776 /*
 777  * Interrupt handler thread
 778  */
 779 static int irq_thread(void *data)
 780 {
 781         static const struct sched_param param = {
 782                 .sched_priority = MAX_USER_RT_PRIO/2,
 783         };
 784         struct irqaction *action = data;
 785         struct irq_desc *desc = irq_to_desc(action->irq);
 786         irqreturn_t (*handler_fn)(struct irq_desc *desc,
 787                         struct irqaction *action);
 788
 789         if (force_irqthreads && test_bit(IRQTF_FORCED_THREAD,
 790                                         &action->thread_flags))
 791                 handler_fn = irq_forced_thread_fn;
 792         else
 793                 handler_fn = irq_thread_fn;
 794
 795         sched_setscheduler(current, SCHED_FIFO, &param);
 796         current->irq_thread = 1;
 797
 798         while (!irq_wait_for_interrupt(action)) {
 799                 irqreturn_t action_ret;
 800
 801                 irq_thread_check_affinity(desc, action);
 802
 803                 action_ret = handler_fn(desc, action);
 804                 if (!noirqdebug)
 805                         note_interrupt(action->irq, desc, action_ret);
 806
 807                 wake_threads_waitq(desc);
 808         }
 809
 810         /*
 811          * This is the regular exit path. __free_irq() is stopping the
 812          * thread via kthread_stop() after calling
 813          * synchronize_irq(). So neither IRQTF_RUNTHREAD nor the
 814          * oneshot mask bit can be set. We cannot verify that as we
 815          * cannot touch the oneshot mask at this point anymore as
 816          * __setup_irq() might have given out currents thread_mask
 817          * again.
 818          *
 819          * Clear irq_thread. Otherwise exit_irq_thread() would make
 820          * fuzz about an active irq thread going into nirvana.
 821          */
 822         current->irq_thread = 0;
 823         return 0;
 824 }
 825
 826 /*
 827  * Called from do_exit()
 828  */
 829 void exit_irq_thread(void)
 830 {
 831         struct task_struct *tsk = current;
 832         struct irq_desc *desc;
 833         struct irqaction *action;
 834
 835         if (!tsk->irq_thread)
 836                 return;
 837
 838         action = kthread_data(tsk);
 839
 840         pr_err("genirq: exiting task \"%s\" (%d) is an active IRQ thread (irq %d)\n",
 841                tsk->comm ? tsk->comm : "", tsk->pid, action->irq);
 842
 843         desc = irq_to_desc(action->irq);
 844
 845         /*
 846          * If IRQTF_RUNTHREAD is set, we need to decrement
 847          * desc->threads_active and wake possible waiters.
 848          */
 849         if (test_and_clear_bit(IRQTF_RUNTHREAD, &action->thread_flags))
 850                 wake_threads_waitq(desc);
 851
 852         /* Prevent a stale desc->threads_oneshot */
 853         irq_finalize_oneshot(desc, action);
 854 }
 855
 856 static void irq_setup_forced_threading(struct irqaction *new)
 857 {
 858         if (!force_irqthreads)
 859                 return;
 860         if (new->flags & (IRQF_NO_THREAD | IRQF_PERCPU | IRQF_ONESHOT))
 861                 return;
 862
 863         new->flags |= IRQF_ONESHOT;
 864
 865         if (!new->thread_fn) {
 866                 set_bit(IRQTF_FORCED_THREAD, &new->thread_flags);
 867                 new->thread_fn = new->handler;
 868                 new->handler = irq_default_primary_handler;
 869         }
 870 }
 871
 872 /*
 873  * Internal function to register an irqaction - typically used to
 874  * allocate special interrupts that are part of the architecture.
 875  */
 876 static int
 877 __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
 878 {
 879         struct irqaction *old, **old_ptr;
 880         unsigned long flags, thread_mask = 0;
 881         int ret, nested, shared = 0;
 882         cpumask_var_t mask;
 883
 884         if (!desc)
 885                 return -EINVAL;
 886
 887         if (desc->irq_data.chip == &no_irq_chip)
 888                 return -ENOSYS;
 889         if (!try_module_get(desc->owner))
 890                 return -ENODEV;
 891         /*
 892          * Some drivers like serial.c use request_irq() heavily,
 893          * so we have to be careful not to interfere with a
 894          * running system.
 895          */
 896         if (new->flags & IRQF_SAMPLE_RANDOM) {
 897                 /*
 898                  * This function might sleep, we want to call it first,
 899                  * outside of the atomic block.
 900                  * Yes, this might clear the entropy pool if the wrong
 901                  * driver is attempted to be loaded, without actually
 902                  * installing a new handler, but is this really a problem,
 903                  * only the sysadmin is able to do this.
 904                  */
 905                 rand_initialize_irq(irq);
 906         }
 907
 908         /*
 909          * Check whether the interrupt nests into another interrupt
 910          * thread.
 911          */
 912         nested = irq_settings_is_nested_thread(desc);
 913         if (nested) {
 914                 if (!new->thread_fn) {
 915                         ret = -EINVAL;
 916                         goto out_mput;
 917                 }
 918                 /*
 919                  * Replace the primary handler which was provided from
 920                  * the driver for non nested interrupt handling by the
 921                  * dummy function which warns when called.
 922                  */
 923                 new->handler = irq_nested_primary_handler;
 924         } else {
 925                 if (irq_settings_can_thread(desc))
 926                         irq_setup_forced_threading(new);
 927         }
 928
 929         /*
 930          * Create a handler thread when a thread function is supplied
 931          * and the interrupt does not nest into another interrupt
 932          * thread.
 933          */
 934         if (new->thread_fn && !nested) {
 935                 struct task_struct *t;
 936
 937                 t = kthread_create(irq_thread, new, "irq/%d-%s", irq,
 938                                    new->name);
 939                 if (IS_ERR(t)) {
 940                         ret = PTR_ERR(t);
 941                         goto out_mput;
 942                 }
 943                 /*
 944                  * We keep the reference to the task struct even if
 945                  * the thread dies to avoid that the interrupt code
 946                  * references an already freed task_struct.
 947                  */
 948                 get_task_struct(t);
 949                 new->thread = t;
 950         }
 951
 952         if (!alloc_cpumask_var(&mask, GFP_KERNEL)) {
 953                 ret = -ENOMEM;
 954                 goto out_thread;
 955         }
 956
 957         /*
 958          * The following block of code has to be executed atomically
 959          */
 960         raw_spin_lock_irqsave(&desc->lock, flags);
 961         old_ptr = &desc->action;
 962         old = *old_ptr;
 963         if (old) {
 964                 /*
 965                  * Can't share interrupts unless both agree to and are
 966                  * the same type (level, edge, polarity). So both flag
 967                  * fields must have IRQF_SHARED set and the bits which
 968                  * set the trigger type must match. Also all must
 969                  * agree on ONESHOT.
 970                  */
 971                 if (!((old->flags & new->flags) & IRQF_SHARED) ||
 972                     ((old->flags ^ new->flags) & IRQF_TRIGGER_MASK) ||
 973                     ((old->flags ^ new->flags) & IRQF_ONESHOT))
 974                         goto mismatch;
 975
 976                 /* All handlers must agree on per-cpuness */
 977                 if ((old->flags & IRQF_PERCPU) !=
 978                     (new->flags & IRQF_PERCPU))
 979                         goto mismatch;
 980
 981                 /* add new interrupt at end of irq queue */
 982                 do {
 983                         /*
 984                          * Or all existing action->thread_mask bits,
 985                          * so we can find the next zero bit for this
 986                          * new action.
 987                          */
 988                         thread_mask |= old->thread_mask;
 989                         old_ptr = &old->next;
 990                         old = *old_ptr;
 991                 } while (old);
 992                 shared = 1;
 993         }
 994
 995         /*
 996          * Setup the thread mask for this irqaction for ONESHOT. For
 997          * !ONESHOT irqs the thread mask is 0 so we can avoid a
 998          * conditional in irq_wake_thread().
 999          */
1000         if (new->flags & IRQF_ONESHOT) {
1001                 /*
1002                  * Unlikely to have 32 resp 64 irqs sharing one line,
1003                  * but who knows.
1004                  */
1005                 if (thread_mask == ~0UL) {
1006                         ret = -EBUSY;
1007                         goto out_mask;
1008                 }
1009                 /*
1010                  * The thread_mask for the action is or'ed to
1011                  * desc->thread_active to indicate that the
1012                  * IRQF_ONESHOT thread handler has been woken, but not
1013                  * yet finished. The bit is cleared when a thread
1014                  * completes. When all threads of a shared interrupt
1015                  * line have completed desc->threads_active becomes
1016                  * zero and the interrupt line is unmasked. See
1017                  * handle.c:irq_wake_thread() for further information.
1018                  *
1019                  * If no thread is woken by primary (hard irq context)
1020                  * interrupt handlers, then desc->threads_active is
1021                  * also checked for zero to unmask the irq line in the
1022                  * affected hard irq flow handlers
1023                  * (handle_[fasteoi|level]_irq).
1024                  *
1025                  * The new action gets the first zero bit of
1026                  * thread_mask assigned. See the loop above which or's
1027                  * all existing action->thread_mask bits.
1028                  */
1029                 new->thread_mask = 1 << ffz(thread_mask);
1030
1031         } else if (new->handler == irq_default_primary_handler) {
1032                 /*
1033                  * The interrupt was requested with handler = NULL, so
1034                  * we use the default primary handler for it. But it
1035                  * does not have the oneshot flag set. In combination
1036                  * with level interrupts this is deadly, because the
1037                  * default primary handler just wakes the thread, then
1038                  * the irq lines is reenabled, but the device still
1039                  * has the level irq asserted. Rinse and repeat....
1040                  *
1041                  * While this works for edge type interrupts, we play
1042                  * it safe and reject unconditionally because we can't
1043                  * say for sure which type this interrupt really
1044                  * has. The type flags are unreliable as the
1045                  * underlying chip implementation can override them.
1046                  */
1047                 pr_err("genirq: Threaded irq requested with handler=NULL and !ONESHOT for irq %d\n",
1048                        irq);
1049                 ret = -EINVAL;
1050                 goto out_mask;
1051         }
1052
1053         if (!shared) {
1054                 init_waitqueue_head(&desc->wait_for_threads);
1055
1056                 /* Setup the type (level, edge polarity) if configured: */
1057                 if (new->flags & IRQF_TRIGGER_MASK) {
1058                         ret = __irq_set_trigger(desc, irq,
1059                                         new->flags & IRQF_TRIGGER_MASK);
1060
1061                         if (ret)
1062                                 goto out_mask;
1063                 }
1064
1065                 desc->istate &= ~(IRQS_AUTODETECT | IRQS_SPURIOUS_DISABLED | \
1066                                   IRQS_ONESHOT | IRQS_WAITING);
1067                 irqd_clear(&desc->irq_data, IRQD_IRQ_INPROGRESS);
1068
1069                 if (new->flags & IRQF_PERCPU) {
1070                         irqd_set(&desc->irq_data, IRQD_PER_CPU);
1071                         irq_settings_set_per_cpu(desc);
1072                 }
1073
1074                 if (new->flags & IRQF_ONESHOT)
1075                         desc->istate |= IRQS_ONESHOT;
1076
1077                 if (irq_settings_can_autoenable(desc))
1078                         irq_startup(desc, true);
1079                 else
1080                         /* Undo nested disables: */
1081                         desc->depth = 1;
1082
1083                 /* Exclude IRQ from balancing if requested */
1084                 if (new->flags & IRQF_NOBALANCING) {
1085                         irq_settings_set_no_balancing(desc);
1086                         irqd_set(&desc->irq_data, IRQD_NO_BALANCING);
1087                 }
1088
1089                 /* Set default affinity mask once everything is setup */
1090                 setup_affinity(irq, desc, mask);
1091
1092         } else if (new->flags & IRQF_TRIGGER_MASK) {
1093                 unsigned int nmsk = new->flags & IRQF_TRIGGER_MASK;
1094                 unsigned int omsk = irq_settings_get_trigger_mask(desc);
1095
1096                 if (nmsk != omsk)
1097                         /* hope the handler works with current  trigger mode */
1098                         pr_warning("genirq: irq %d uses trigger mode %u; requested %u\n",
1099                                    irq, nmsk, omsk);
1100         }
1101
1102         new->irq = irq;
1103         *old_ptr = new;
1104
1105         /* Reset broken irq detection when installing new handler */
1106         desc->irq_count = 0;
1107         desc->irqs_unhandled = 0;
1108
1109         /*
1110          * Check whether we disabled the irq via the spurious handler
1111          * before. Reenable it and give it another chance.
1112          */
1113         if (shared && (desc->istate & IRQS_SPURIOUS_DISABLED)) {
1114                 desc->istate &= ~IRQS_SPURIOUS_DISABLED;
1115                 __enable_irq(desc, irq, false);
1116         }
1117
1118         raw_spin_unlock_irqrestore(&desc->lock, flags);
1119
1120         /*
1121          * Strictly no need to wake it up, but hung_task complains
1122          * when no hard interrupt wakes the thread up.
1123          */
1124         if (new->thread)
1125                 wake_up_process(new->thread);
1126
1127         register_irq_proc(irq, desc);
1128         new->dir = NULL;
1129         register_handler_proc(irq, new);
1130         free_cpumask_var(mask);
1131
1132         return 0;
1133
1134 mismatch:
1135         if (!(new->flags & IRQF_PROBE_SHARED)) {
1136                 pr_err("genirq: Flags mismatch irq %d. %08x (%s) vs. %08x (%s)\n",
1137                        irq, new->flags, new->name, old->flags, old->name);
1138 #ifdef CONFIG_DEBUG_SHIRQ
1139                 dump_stack();
1140 #endif
1141         }
1142         ret = -EBUSY;
1143
1144 out_mask:
1145         raw_spin_unlock_irqrestore(&desc->lock, flags);
1146         free_cpumask_var(mask);
1147
1148 out_thread:
1149         if (new->thread) {
1150                 struct task_struct *t = new->thread;
1151
1152                 new->thread = NULL;
1153                 kthread_stop(t);
1154                 put_task_struct(t);
1155         }
1156 out_mput:
1157         module_put(desc->owner);
1158         return ret;
1159 }
1160
1161 /**
1162  *      setup_irq - setup an interrupt
1163  *      @irq: Interrupt line to setup
1164  *      @act: irqaction for the interrupt
1165  *
1166  * Used to statically setup interrupts in the early boot process.
1167  */
1168 int setup_irq(unsigned int irq, struct irqaction *act)
1169 {
1170         int retval;
1171         struct irq_desc *desc = irq_to_desc(irq);
1172
1173         if (WARN_ON(irq_settings_is_per_cpu_devid(desc)))
1174                 return -EINVAL;
1175         chip_bus_lock(desc);
1176         retval = __setup_irq(irq, desc, act);
1177         chip_bus_sync_unlock(desc);
1178
1179         return retval;
1180 }
1181 EXPORT_SYMBOL_GPL(setup_irq);
1182
1183 /*
1184  * Internal function to unregister an irqaction - used to free
1185  * regular and special interrupts that are part of the architecture.
1186  */
1187 static struct irqaction *__free_irq(unsigned int irq, void *dev_id)
1188 {
1189         struct irq_desc *desc = irq_to_desc(irq);
1190         struct irqaction *action, **action_ptr;
1191         unsigned long flags;
1192
1193         WARN(in_interrupt(), "Trying to free IRQ %d from IRQ context!\n", irq);
1194
1195         if (!desc)
1196                 return NULL;
1197
1198         raw_spin_lock_irqsave(&desc->lock, flags);
1199
1200         /*
1201          * There can be multiple actions per IRQ descriptor, find the right
1202          * one based on the dev_id:
1203          */
1204         action_ptr = &desc->action;
1205         for (;;) {
1206                 action = *action_ptr;
1207
1208                 if (!action) {
1209                         WARN(1, "Trying to free already-free IRQ %d\n", irq);
1210                         raw_spin_unlock_irqrestore(&desc->lock, flags);
1211
1212                         return NULL;
1213                 }
1214
1215                 if (action->dev_id == dev_id)
1216                         break;
1217                 action_ptr = &action->next;
1218         }
1219
1220         /* Found it - now remove it from the list of entries: */
1221         *action_ptr = action->next;
1222
1223         /* If this was the last handler, shut down the IRQ line: */
1224         if (!desc->action)
1225                 irq_shutdown(desc);
1226
1227 #ifdef CONFIG_SMP
1228         /* make sure affinity_hint is cleaned up */
1229         if (WARN_ON_ONCE(desc->affinity_hint))
1230                 desc->affinity_hint = NULL;
1231 #endif
1232
1233         raw_spin_unlock_irqrestore(&desc->lock, flags);
1234
1235         unregister_handler_proc(irq, action);
1236
1237         /* Make sure it's not being used on another CPU: */
1238         synchronize_irq(irq);
1239
1240 #ifdef CONFIG_DEBUG_SHIRQ
1241         /*
1242          * It's a shared IRQ -- the driver ought to be prepared for an IRQ
1243          * event to happen even now it's being freed, so let's make sure that
1244          * is so by doing an extra call to the handler ....
1245          *
1246          * ( We do this after actually deregistering it, to make sure that a
1247          *   'real' IRQ doesn't run in * parallel with our fake. )
1248          */
1249         if (action->flags & IRQF_SHARED) {
1250                 local_irq_save(flags);
1251                 action->handler(irq, dev_id);
1252                 local_irq_restore(flags);
1253         }
1254 #endif
1255
1256         if (action->thread) {
1257                 kthread_stop(action->thread);
1258                 put_task_struct(action->thread);
1259         }
1260
1261         module_put(desc->owner);
1262         return action;
1263 }
1264
1265 /**
1266  *      remove_irq - free an interrupt
1267  *      @irq: Interrupt line to free
1268  *      @act: irqaction for the interrupt
1269  *
1270  * Used to remove interrupts statically setup by the early boot process.
1271  */
1272 void remove_irq(unsigned int irq, struct irqaction *act)
1273 {
1274         struct irq_desc *desc = irq_to_desc(irq);
1275
1276         if (desc && !WARN_ON(irq_settings_is_per_cpu_devid(desc)))
1277             __free_irq(irq, act->dev_id);
1278 }
1279 EXPORT_SYMBOL_GPL(remove_irq);
1280
1281 /**
1282  *      free_irq - free an interrupt allocated with request_irq
1283  *      @irq: Interrupt line to free
1284  *      @dev_id: Device identity to free
1285  *
1286  *      Remove an interrupt handler. The handler is removed and if the
1287  *      interrupt line is no longer in use by any driver it is disabled.
1288  *      On a shared IRQ the caller must ensure the interrupt is disabled
1289  *      on the card it drives before calling this function. The function
1290  *      does not return until any executing interrupts for this IRQ
1291  *      have completed.
1292  *
1293  *      This function must not be called from interrupt context.
1294  */
1295 void free_irq(unsigned int irq, void *dev_id)
1296 {
1297         struct irq_desc *desc = irq_to_desc(irq);
1298
1299         if (!desc || WARN_ON(irq_settings_is_per_cpu_devid(desc)))
1300                 return;
1301
1302 #ifdef CONFIG_SMP
1303         if (WARN_ON(desc->affinity_notify))
1304                 desc->affinity_notify = NULL;
1305 #endif
1306
1307         chip_bus_lock(desc);
1308         kfree(__free_irq(irq, dev_id));
1309         chip_bus_sync_unlock(desc);
1310 }
1311 EXPORT_SYMBOL(free_irq);
1312
1313 /**
1314  *      request_threaded_irq - allocate an interrupt line
1315  *      @irq: Interrupt line to allocate
1316  *      @handler: Function to be called when the IRQ occurs.
1317  *                Primary handler for threaded interrupts
1318  *                If NULL and thread_fn != NULL the default
1319  *                primary handler is installed
1320  *      @thread_fn: Function called from the irq handler thread
1321  *                  If NULL, no irq thread is created
1322  *      @irqflags: Interrupt type flags
1323  *      @devname: An ascii name for the claiming device
1324  *      @dev_id: A cookie passed back to the handler function
1325  *
1326  *      This call allocates interrupt resources and enables the
1327  *      interrupt line and IRQ handling. From the point this
1328  *      call is made your handler function may be invoked. Since
1329  *      your handler function must clear any interrupt the board
1330  *      raises, you must take care both to initialise your hardware
1331  *      and to set up the interrupt handler in the right order.
1332  *
1333  *      If you want to set up a threaded irq handler for your device
1334  *      then you need to supply @handler and @thread_fn. @handler is
1335  *      still called in hard interrupt context and has to check
1336  *      whether the interrupt originates from the device. If yes it
1337  *      needs to disable the interrupt on the device and return
1338  *      IRQ_WAKE_THREAD which will wake up the handler thread and run
1339  *      @thread_fn. This split handler design is necessary to support
1340  *      shared interrupts.
1341  *
1342  *      Dev_id must be globally unique. Normally the address of the
1343  *      device data structure is used as the cookie. Since the handler
1344  *      receives this value it makes sense to use it.
1345  *
1346  *      If your interrupt is shared you must pass a non NULL dev_id
1347  *      as this is required when freeing the interrupt.
1348  *
1349  *      Flags:
1350  *
1351  *      IRQF_SHARED             Interrupt is shared
1352  *      IRQF_SAMPLE_RANDOM      The interrupt can be used for entropy
1353  *      IRQF_TRIGGER_*          Specify active edge(s) or level
1354  *
1355  */
1356 int request_threaded_irq(unsigned int irq, irq_handler_t handler,
1357                          irq_handler_t thread_fn, unsigned long irqflags,
1358                          const char *devname, void *dev_id)
1359 {
1360         struct irqaction *action;
1361         struct irq_desc *desc;
1362         int retval;
1363
1364         /*
1365          * Sanity-check: shared interrupts must pass in a real dev-ID,
1366          * otherwise we'll have trouble later trying to figure out
1367          * which interrupt is which (messes up the interrupt freeing
1368          * logic etc).
1369          */
1370         if ((irqflags & IRQF_SHARED) && !dev_id)
1371                 return -EINVAL;
1372
1373         desc = irq_to_desc(irq);
1374         if (!desc)
1375                 return -EINVAL;
1376
1377         if (!irq_settings_can_request(desc) ||
1378             WARN_ON(irq_settings_is_per_cpu_devid(desc)))
1379                 return -EINVAL;
1380
1381         if (!handler) {
1382                 if (!thread_fn)
1383                         return -EINVAL;
1384                 handler = irq_default_primary_handler;
1385         }
1386
1387         action = kzalloc(sizeof(struct irqaction), GFP_KERNEL);
1388         if (!action)
1389                 return -ENOMEM;
1390
1391         action->handler = handler;
1392         action->thread_fn = thread_fn;
1393         action->flags = irqflags;
1394         action->name = devname;
1395         action->dev_id = dev_id;
1396
1397         chip_bus_lock(desc);
1398         retval = __setup_irq(irq, desc, action);
1399         chip_bus_sync_unlock(desc);
1400
1401         if (retval)
1402                 kfree(action);
1403
1404 #ifdef CONFIG_DEBUG_SHIRQ_FIXME
1405         if (!retval && (irqflags & IRQF_SHARED)) {
1406                 /*
1407                  * It's a shared IRQ -- the driver ought to be prepared for it
1408                  * to happen immediately, so let's make sure....
1409                  * We disable the irq to make sure that a 'real' IRQ doesn't
1410                  * run in parallel with our fake.
1411                  */
1412                 unsigned long flags;
1413
1414                 disable_irq(irq);
1415                 local_irq_save(flags);
1416
1417                 handler(irq, dev_id);
1418
1419                 local_irq_restore(flags);
1420                 enable_irq(irq);
1421         }
1422 #endif
1423         return retval;
1424 }
1425 EXPORT_SYMBOL(request_threaded_irq);
1426
1427 /**
1428  *      request_any_context_irq - allocate an interrupt line
1429  *      @irq: Interrupt line to allocate
1430  *      @handler: Function to be called when the IRQ occurs.
1431  *                Threaded handler for threaded interrupts.
1432  *      @flags: Interrupt type flags
1433  *      @name: An ascii name for the claiming device
1434  *      @dev_id: A cookie passed back to the handler function
1435  *
1436  *      This call allocates interrupt resources and enables the
1437  *      interrupt line and IRQ handling. It selects either a
1438  *      hardirq or threaded handling method depending on the
1439  *      context.
1440  *
1441  *      On failure, it returns a negative value. On success,
1442  *      it returns either IRQC_IS_HARDIRQ or IRQC_IS_NESTED.
1443  */
1444 int request_any_context_irq(unsigned int irq, irq_handler_t handler,
1445                             unsigned long flags, const char *name, void *dev_id)
1446 {
1447         struct irq_desc *desc = irq_to_desc(irq);
1448         int ret;
1449
1450         if (!desc)
1451                 return -EINVAL;
1452
1453         if (irq_settings_is_nested_thread(desc)) {
1454                 ret = request_threaded_irq(irq, NULL, handler,
1455                                            flags, name, dev_id);
1456                 return !ret ? IRQC_IS_NESTED : ret;
1457         }
1458
1459         ret = request_irq(irq, handler, flags, name, dev_id);
1460         return !ret ? IRQC_IS_HARDIRQ : ret;
1461 }
1462 EXPORT_SYMBOL_GPL(request_any_context_irq);
1463
1464 void enable_percpu_irq(unsigned int irq, unsigned int type)
1465 {
1466         unsigned int cpu = smp_processor_id();
1467         unsigned long flags;
1468         struct irq_desc *desc = irq_get_desc_lock(irq, &flags, IRQ_GET_DESC_CHECK_PERCPU);
1469
1470         if (!desc)
1471                 return;
1472
1473         type &= IRQ_TYPE_SENSE_MASK;
1474         if (type != IRQ_TYPE_NONE) {
1475                 int ret;
1476
1477                 ret = __irq_set_trigger(desc, irq, type);
1478
1479                 if (ret) {
1480                         WARN(1, "failed to set type for IRQ%d\n", irq);
1481                         goto out;
1482                 }
1483         }
1484
1485         irq_percpu_enable(desc, cpu);
1486 out:
1487         irq_put_desc_unlock(desc, flags);
1488 }
1489
1490 void disable_percpu_irq(unsigned int irq)
1491 {
1492         unsigned int cpu = smp_processor_id();
1493         unsigned long flags;
1494         struct irq_desc *desc = irq_get_desc_lock(irq, &flags, IRQ_GET_DESC_CHECK_PERCPU);
1495
1496         if (!desc)
1497                 return;
1498
1499         irq_percpu_disable(desc, cpu);
1500         irq_put_desc_unlock(desc, flags);
1501 }
1502
1503 /*
1504  * Internal function to unregister a percpu irqaction.
1505  */
1506 static struct irqaction *__free_percpu_irq(unsigned int irq, void __percpu *dev_id)
1507 {
1508         struct irq_desc *desc = irq_to_desc(irq);
1509         struct irqaction *action;
1510         unsigned long flags;
1511
1512         WARN(in_interrupt(), "Trying to free IRQ %d from IRQ context!\n", irq);
1513
1514         if (!desc)
1515                 return NULL;
1516
1517         raw_spin_lock_irqsave(&desc->lock, flags);
1518
1519         action = desc->action;
1520         if (!action || action->percpu_dev_id != dev_id) {
1521                 WARN(1, "Trying to free already-free IRQ %d\n", irq);
1522                 goto bad;
1523         }
1524
1525         if (!cpumask_empty(desc->percpu_enabled)) {
1526                 WARN(1, "percpu IRQ %d still enabled on CPU%d!\n",
1527                      irq, cpumask_first(desc->percpu_enabled));
1528                 goto bad;
1529         }
1530
1531         /* Found it - now remove it from the list of entries: */
1532         desc->action = NULL;
1533
1534         raw_spin_unlock_irqrestore(&desc->lock, flags);
1535
1536         unregister_handler_proc(irq, action);
1537
1538         module_put(desc->owner);
1539         return action;
1540
1541 bad:
1542         raw_spin_unlock_irqrestore(&desc->lock, flags);
1543         return NULL;
1544 }
1545
1546 /**
1547  *      remove_percpu_irq - free a per-cpu interrupt
1548  *      @irq: Interrupt line to free
1549  *      @act: irqaction for the interrupt
1550  *
1551  * Used to remove interrupts statically setup by the early boot process.
1552  */
1553 void remove_percpu_irq(unsigned int irq, struct irqaction *act)
1554 {
1555         struct irq_desc *desc = irq_to_desc(irq);
1556
1557         if (desc && irq_settings_is_per_cpu_devid(desc))
1558             __free_percpu_irq(irq, act->percpu_dev_id);
1559 }
1560
1561 /**
1562  *      free_percpu_irq - free an interrupt allocated with request_percpu_irq
1563  *      @irq: Interrupt line to free
1564  *      @dev_id: Device identity to free
1565  *
1566  *      Remove a percpu interrupt handler. The handler is removed, but
1567  *      the interrupt line is not disabled. This must be done on each
1568  *      CPU before calling this function. The function does not return
1569  *      until any executing interrupts for this IRQ have completed.
1570  *
1571  *      This function must not be called from interrupt context.
1572  */
1573 void free_percpu_irq(unsigned int irq, void __percpu *dev_id)
1574 {
1575         struct irq_desc *desc = irq_to_desc(irq);
1576
1577         if (!desc || !irq_settings_is_per_cpu_devid(desc))
1578                 return;
1579
1580         chip_bus_lock(desc);
1581         kfree(__free_percpu_irq(irq, dev_id));
1582         chip_bus_sync_unlock(desc);
1583 }
1584
1585 /**
1586  *      setup_percpu_irq - setup a per-cpu interrupt
1587  *      @irq: Interrupt line to setup
1588  *      @act: irqaction for the interrupt
1589  *
1590  * Used to statically setup per-cpu interrupts in the early boot process.
1591  */
1592 int setup_percpu_irq(unsigned int irq, struct irqaction *act)
1593 {
1594         struct irq_desc *desc = irq_to_desc(irq);
1595         int retval;
1596
1597         if (!desc || !irq_settings_is_per_cpu_devid(desc))
1598                 return -EINVAL;
1599         chip_bus_lock(desc);
1600         retval = __setup_irq(irq, desc, act);
1601         chip_bus_sync_unlock(desc);
1602
1603         return retval;
1604 }
1605
1606 /**
1607  *      request_percpu_irq - allocate a percpu interrupt line
1608  *      @irq: Interrupt line to allocate
1609  *      @handler: Function to be called when the IRQ occurs.
1610  *      @devname: An ascii name for the claiming device
1611  *      @dev_id: A percpu cookie passed back to the handler function
1612  *
1613  *      This call allocates interrupt resources, but doesn't
1614  *      automatically enable the interrupt. It has to be done on each
1615  *      CPU using enable_percpu_irq().
1616  *
1617  *      Dev_id must be globally unique. It is a per-cpu variable, and
1618  *      the handler gets called with the interrupted CPU's instance of
1619  *      that variable.
1620  */
1621 int request_percpu_irq(unsigned int irq, irq_handler_t handler,
1622                        const char *devname, void __percpu *dev_id)
1623 {
1624         struct irqaction *action;
1625         struct irq_desc *desc;
1626         int retval;
1627
1628         if (!dev_id)
1629                 return -EINVAL;
1630
1631         desc = irq_to_desc(irq);
1632         if (!desc || !irq_settings_can_request(desc) ||
1633             !irq_settings_is_per_cpu_devid(desc))
1634                 return -EINVAL;
1635
1636         action = kzalloc(sizeof(struct irqaction), GFP_KERNEL);
1637         if (!action)
1638                 return -ENOMEM;
1639
1640         action->handler = handler;
1641         action->flags = IRQF_PERCPU | IRQF_NO_SUSPEND;
1642         action->name = devname;
1643         action->percpu_dev_id = dev_id;
1644
1645         chip_bus_lock(desc);
1646         retval = __setup_irq(irq, desc, action);
1647         chip_bus_sync_unlock(desc);
1648
1649         if (retval)
1650                 kfree(action);
1651
1652         return retval;
1653 }