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("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("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         printk(KERN_ERR
 841                "exiting task \"%s\" (%d) is an active IRQ thread (irq %d)\n",
 842                tsk->comm ? tsk->comm : "", tsk->pid, action->irq);
 843
 844         desc = irq_to_desc(action->irq);
 845
 846         /*
 847          * If IRQTF_RUNTHREAD is set, we need to decrement
 848          * desc->threads_active and wake possible waiters.
 849          */
 850         if (test_and_clear_bit(IRQTF_RUNTHREAD, &action->thread_flags))
 851                 wake_threads_waitq(desc);
 852
 853         /* Prevent a stale desc->threads_oneshot */
 854         irq_finalize_oneshot(desc, action);
 855 }
 856
 857 static void irq_setup_forced_threading(struct irqaction *new)
 858 {
 859         if (!force_irqthreads)
 860                 return;
 861         if (new->flags & (IRQF_NO_THREAD | IRQF_PERCPU | IRQF_ONESHOT))
 862                 return;
 863
 864         new->flags |= IRQF_ONESHOT;
 865
 866         if (!new->thread_fn) {
 867                 set_bit(IRQTF_FORCED_THREAD, &new->thread_flags);
 868                 new->thread_fn = new->handler;
 869                 new->handler = irq_default_primary_handler;
 870         }
 871 }
 872
 873 /*
 874  * Internal function to register an irqaction - typically used to
 875  * allocate special interrupts that are part of the architecture.
 876  */
 877 static int
 878 __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
 879 {
 880         struct irqaction *old, **old_ptr;
 881         const char *old_name = NULL;
 882         unsigned long flags, thread_mask = 0;
 883         int ret, nested, shared = 0;
 884         cpumask_var_t mask;
 885
 886         if (!desc)
 887                 return -EINVAL;
 888
 889         if (desc->irq_data.chip == &no_irq_chip)
 890                 return -ENOSYS;
 891         if (!try_module_get(desc->owner))
 892                 return -ENODEV;
 893         /*
 894          * Some drivers like serial.c use request_irq() heavily,
 895          * so we have to be careful not to interfere with a
 896          * running system.
 897          */
 898         if (new->flags & IRQF_SAMPLE_RANDOM) {
 899                 /*
 900                  * This function might sleep, we want to call it first,
 901                  * outside of the atomic block.
 902                  * Yes, this might clear the entropy pool if the wrong
 903                  * driver is attempted to be loaded, without actually
 904                  * installing a new handler, but is this really a problem,
 905                  * only the sysadmin is able to do this.
 906                  */
 907                 rand_initialize_irq(irq);
 908         }
 909
 910         /*
 911          * Check whether the interrupt nests into another interrupt
 912          * thread.
 913          */
 914         nested = irq_settings_is_nested_thread(desc);
 915         if (nested) {
 916                 if (!new->thread_fn) {
 917                         ret = -EINVAL;
 918                         goto out_mput;
 919                 }
 920                 /*
 921                  * Replace the primary handler which was provided from
 922                  * the driver for non nested interrupt handling by the
 923                  * dummy function which warns when called.
 924                  */
 925                 new->handler = irq_nested_primary_handler;
 926         } else {
 927                 if (irq_settings_can_thread(desc))
 928                         irq_setup_forced_threading(new);
 929         }
 930
 931         /*
 932          * Create a handler thread when a thread function is supplied
 933          * and the interrupt does not nest into another interrupt
 934          * thread.
 935          */
 936         if (new->thread_fn && !nested) {
 937                 struct task_struct *t;
 938
 939                 t = kthread_create(irq_thread, new, "irq/%d-%s", irq,
 940                                    new->name);
 941                 if (IS_ERR(t)) {
 942                         ret = PTR_ERR(t);
 943                         goto out_mput;
 944                 }
 945                 /*
 946                  * We keep the reference to the task struct even if
 947                  * the thread dies to avoid that the interrupt code
 948                  * references an already freed task_struct.
 949                  */
 950                 get_task_struct(t);
 951                 new->thread = t;
 952         }
 953
 954         if (!alloc_cpumask_var(&mask, GFP_KERNEL)) {
 955                 ret = -ENOMEM;
 956                 goto out_thread;
 957         }
 958
 959         /*
 960          * The following block of code has to be executed atomically
 961          */
 962         raw_spin_lock_irqsave(&desc->lock, flags);
 963         old_ptr = &desc->action;
 964         old = *old_ptr;
 965         if (old) {
 966                 /*
 967                  * Can't share interrupts unless both agree to and are
 968                  * the same type (level, edge, polarity). So both flag
 969                  * fields must have IRQF_SHARED set and the bits which
 970                  * set the trigger type must match. Also all must
 971                  * agree on ONESHOT.
 972                  */
 973                 if (!((old->flags & new->flags) & IRQF_SHARED) ||
 974                     ((old->flags ^ new->flags) & IRQF_TRIGGER_MASK) ||
 975                     ((old->flags ^ new->flags) & IRQF_ONESHOT)) {
 976                         old_name = old->name;
 977                         goto mismatch;
 978                 }
 979
 980                 /* All handlers must agree on per-cpuness */
 981                 if ((old->flags & IRQF_PERCPU) !=
 982                     (new->flags & IRQF_PERCPU))
 983                         goto mismatch;
 984
 985                 /* add new interrupt at end of irq queue */
 986                 do {
 987                         /*
 988                          * Or all existing action->thread_mask bits,
 989                          * so we can find the next zero bit for this
 990                          * new action.
 991                          */
 992                         thread_mask |= old->thread_mask;
 993                         old_ptr = &old->next;
 994                         old = *old_ptr;
 995                 } while (old);
 996                 shared = 1;
 997         }
 998
 999         /*
1000          * Setup the thread mask for this irqaction for ONESHOT. For
1001          * !ONESHOT irqs the thread mask is 0 so we can avoid a
1002          * conditional in irq_wake_thread().
1003          */
1004         if (new->flags & IRQF_ONESHOT) {
1005                 /*
1006                  * Unlikely to have 32 resp 64 irqs sharing one line,
1007                  * but who knows.
1008                  */
1009                 if (thread_mask == ~0UL) {
1010                         ret = -EBUSY;
1011                         goto out_mask;
1012                 }
1013                 /*
1014                  * The thread_mask for the action is or'ed to
1015                  * desc->thread_active to indicate that the
1016                  * IRQF_ONESHOT thread handler has been woken, but not
1017                  * yet finished. The bit is cleared when a thread
1018                  * completes. When all threads of a shared interrupt
1019                  * line have completed desc->threads_active becomes
1020                  * zero and the interrupt line is unmasked. See
1021                  * handle.c:irq_wake_thread() for further information.
1022                  *
1023                  * If no thread is woken by primary (hard irq context)
1024                  * interrupt handlers, then desc->threads_active is
1025                  * also checked for zero to unmask the irq line in the
1026                  * affected hard irq flow handlers
1027                  * (handle_[fasteoi|level]_irq).
1028                  *
1029                  * The new action gets the first zero bit of
1030                  * thread_mask assigned. See the loop above which or's
1031                  * all existing action->thread_mask bits.
1032                  */
1033                 new->thread_mask = 1 << ffz(thread_mask);
1034
1035         } else if (new->handler == irq_default_primary_handler) {
1036                 /*
1037                  * The interrupt was requested with handler = NULL, so
1038                  * we use the default primary handler for it. But it
1039                  * does not have the oneshot flag set. In combination
1040                  * with level interrupts this is deadly, because the
1041                  * default primary handler just wakes the thread, then
1042                  * the irq lines is reenabled, but the device still
1043                  * has the level irq asserted. Rinse and repeat....
1044                  *
1045                  * While this works for edge type interrupts, we play
1046                  * it safe and reject unconditionally because we can't
1047                  * say for sure which type this interrupt really
1048                  * has. The type flags are unreliable as the
1049                  * underlying chip implementation can override them.
1050                  */
1051                 pr_err("genirq: Threaded irq requested with handler=NULL and !ONESHOT for irq %d\n",
1052                        irq);
1053                 ret = -EINVAL;
1054                 goto out_mask;
1055         }
1056
1057         if (!shared) {
1058                 init_waitqueue_head(&desc->wait_for_threads);
1059
1060                 /* Setup the type (level, edge polarity) if configured: */
1061                 if (new->flags & IRQF_TRIGGER_MASK) {
1062                         ret = __irq_set_trigger(desc, irq,
1063                                         new->flags & IRQF_TRIGGER_MASK);
1064
1065                         if (ret)
1066                                 goto out_mask;
1067                 }
1068
1069                 desc->istate &= ~(IRQS_AUTODETECT | IRQS_SPURIOUS_DISABLED | \
1070                                   IRQS_ONESHOT | IRQS_WAITING);
1071                 irqd_clear(&desc->irq_data, IRQD_IRQ_INPROGRESS);
1072
1073                 if (new->flags & IRQF_PERCPU) {
1074                         irqd_set(&desc->irq_data, IRQD_PER_CPU);
1075                         irq_settings_set_per_cpu(desc);
1076                 }
1077
1078                 if (new->flags & IRQF_ONESHOT)
1079                         desc->istate |= IRQS_ONESHOT;
1080
1081                 if (irq_settings_can_autoenable(desc))
1082                         irq_startup(desc, true);
1083                 else
1084                         /* Undo nested disables: */
1085                         desc->depth = 1;
1086
1087                 /* Exclude IRQ from balancing if requested */
1088                 if (new->flags & IRQF_NOBALANCING) {
1089                         irq_settings_set_no_balancing(desc);
1090                         irqd_set(&desc->irq_data, IRQD_NO_BALANCING);
1091                 }
1092
1093                 /* Set default affinity mask once everything is setup */
1094                 setup_affinity(irq, desc, mask);
1095
1096         } else if (new->flags & IRQF_TRIGGER_MASK) {
1097                 unsigned int nmsk = new->flags & IRQF_TRIGGER_MASK;
1098                 unsigned int omsk = irq_settings_get_trigger_mask(desc);
1099
1100                 if (nmsk != omsk)
1101                         /* hope the handler works with current  trigger mode */
1102                         pr_warning("IRQ %d uses trigger mode %u; requested %u\n",
1103                                    irq, nmsk, omsk);
1104         }
1105
1106         new->irq = irq;
1107         *old_ptr = new;
1108
1109         /* Reset broken irq detection when installing new handler */
1110         desc->irq_count = 0;
1111         desc->irqs_unhandled = 0;
1112
1113         /*
1114          * Check whether we disabled the irq via the spurious handler
1115          * before. Reenable it and give it another chance.
1116          */
1117         if (shared && (desc->istate & IRQS_SPURIOUS_DISABLED)) {
1118                 desc->istate &= ~IRQS_SPURIOUS_DISABLED;
1119                 __enable_irq(desc, irq, false);
1120         }
1121
1122         raw_spin_unlock_irqrestore(&desc->lock, flags);
1123
1124         /*
1125          * Strictly no need to wake it up, but hung_task complains
1126          * when no hard interrupt wakes the thread up.
1127          */
1128         if (new->thread)
1129                 wake_up_process(new->thread);
1130
1131         register_irq_proc(irq, desc);
1132         new->dir = NULL;
1133         register_handler_proc(irq, new);
1134         free_cpumask_var(mask);
1135
1136         return 0;
1137
1138 mismatch:
1139 #ifdef CONFIG_DEBUG_SHIRQ
1140         if (!(new->flags & IRQF_PROBE_SHARED)) {
1141                 printk(KERN_ERR "IRQ handler type mismatch for IRQ %d\n", irq);
1142                 if (old_name)
1143                         printk(KERN_ERR "current handler: %s\n", old_name);
1144                 dump_stack();
1145         }
1146 #endif
1147         ret = -EBUSY;
1148
1149 out_mask:
1150         raw_spin_unlock_irqrestore(&desc->lock, flags);
1151         free_cpumask_var(mask);
1152
1153 out_thread:
1154         if (new->thread) {
1155                 struct task_struct *t = new->thread;
1156
1157                 new->thread = NULL;
1158                 kthread_stop(t);
1159                 put_task_struct(t);
1160         }
1161 out_mput:
1162         module_put(desc->owner);
1163         return ret;
1164 }
1165
1166 /**
1167  *      setup_irq - setup an interrupt
1168  *      @irq: Interrupt line to setup
1169  *      @act: irqaction for the interrupt
1170  *
1171  * Used to statically setup interrupts in the early boot process.
1172  */
1173 int setup_irq(unsigned int irq, struct irqaction *act)
1174 {
1175         int retval;
1176         struct irq_desc *desc = irq_to_desc(irq);
1177
1178         if (WARN_ON(irq_settings_is_per_cpu_devid(desc)))
1179                 return -EINVAL;
1180         chip_bus_lock(desc);
1181         retval = __setup_irq(irq, desc, act);
1182         chip_bus_sync_unlock(desc);
1183
1184         return retval;
1185 }
1186 EXPORT_SYMBOL_GPL(setup_irq);
1187
1188 /*
1189  * Internal function to unregister an irqaction - used to free
1190  * regular and special interrupts that are part of the architecture.
1191  */
1192 static struct irqaction *__free_irq(unsigned int irq, void *dev_id)
1193 {
1194         struct irq_desc *desc = irq_to_desc(irq);
1195         struct irqaction *action, **action_ptr;
1196         unsigned long flags;
1197
1198         WARN(in_interrupt(), "Trying to free IRQ %d from IRQ context!\n", irq);
1199
1200         if (!desc)
1201                 return NULL;
1202
1203         raw_spin_lock_irqsave(&desc->lock, flags);
1204
1205         /*
1206          * There can be multiple actions per IRQ descriptor, find the right
1207          * one based on the dev_id:
1208          */
1209         action_ptr = &desc->action;
1210         for (;;) {
1211                 action = *action_ptr;
1212
1213                 if (!action) {
1214                         WARN(1, "Trying to free already-free IRQ %d\n", irq);
1215                         raw_spin_unlock_irqrestore(&desc->lock, flags);
1216
1217                         return NULL;
1218                 }
1219
1220                 if (action->dev_id == dev_id)
1221                         break;
1222                 action_ptr = &action->next;
1223         }
1224
1225         /* Found it - now remove it from the list of entries: */
1226         *action_ptr = action->next;
1227
1228         /* Currently used only by UML, might disappear one day: */
1229 #ifdef CONFIG_IRQ_RELEASE_METHOD
1230         if (desc->irq_data.chip->release)
1231                 desc->irq_data.chip->release(irq, dev_id);
1232 #endif
1233
1234         /* If this was the last handler, shut down the IRQ line: */
1235         if (!desc->action)
1236                 irq_shutdown(desc);
1237
1238 #ifdef CONFIG_SMP
1239         /* make sure affinity_hint is cleaned up */
1240         if (WARN_ON_ONCE(desc->affinity_hint))
1241                 desc->affinity_hint = NULL;
1242 #endif
1243
1244         raw_spin_unlock_irqrestore(&desc->lock, flags);
1245
1246         unregister_handler_proc(irq, action);
1247
1248         /* Make sure it's not being used on another CPU: */
1249         synchronize_irq(irq);
1250
1251 #ifdef CONFIG_DEBUG_SHIRQ
1252         /*
1253          * It's a shared IRQ -- the driver ought to be prepared for an IRQ
1254          * event to happen even now it's being freed, so let's make sure that
1255          * is so by doing an extra call to the handler ....
1256          *
1257          * ( We do this after actually deregistering it, to make sure that a
1258          *   'real' IRQ doesn't run in * parallel with our fake. )
1259          */
1260         if (action->flags & IRQF_SHARED) {
1261                 local_irq_save(flags);
1262                 action->handler(irq, dev_id);
1263                 local_irq_restore(flags);
1264         }
1265 #endif
1266
1267         if (action->thread) {
1268                 kthread_stop(action->thread);
1269                 put_task_struct(action->thread);
1270         }
1271
1272         module_put(desc->owner);
1273         return action;
1274 }
1275
1276 /**
1277  *      remove_irq - free an interrupt
1278  *      @irq: Interrupt line to free
1279  *      @act: irqaction for the interrupt
1280  *
1281  * Used to remove interrupts statically setup by the early boot process.
1282  */
1283 void remove_irq(unsigned int irq, struct irqaction *act)
1284 {
1285         struct irq_desc *desc = irq_to_desc(irq);
1286
1287         if (desc && !WARN_ON(irq_settings_is_per_cpu_devid(desc)))
1288             __free_irq(irq, act->dev_id);
1289 }
1290 EXPORT_SYMBOL_GPL(remove_irq);
1291
1292 /**
1293  *      free_irq - free an interrupt allocated with request_irq
1294  *      @irq: Interrupt line to free
1295  *      @dev_id: Device identity to free
1296  *
1297  *      Remove an interrupt handler. The handler is removed and if the
1298  *      interrupt line is no longer in use by any driver it is disabled.
1299  *      On a shared IRQ the caller must ensure the interrupt is disabled
1300  *      on the card it drives before calling this function. The function
1301  *      does not return until any executing interrupts for this IRQ
1302  *      have completed.
1303  *
1304  *      This function must not be called from interrupt context.
1305  */
1306 void free_irq(unsigned int irq, void *dev_id)
1307 {
1308         struct irq_desc *desc = irq_to_desc(irq);
1309
1310         if (!desc || WARN_ON(irq_settings_is_per_cpu_devid(desc)))
1311                 return;
1312
1313 #ifdef CONFIG_SMP
1314         if (WARN_ON(desc->affinity_notify))
1315                 desc->affinity_notify = NULL;
1316 #endif
1317
1318         chip_bus_lock(desc);
1319         kfree(__free_irq(irq, dev_id));
1320         chip_bus_sync_unlock(desc);
1321 }
1322 EXPORT_SYMBOL(free_irq);
1323
1324 /**
1325  *      request_threaded_irq - allocate an interrupt line
1326  *      @irq: Interrupt line to allocate
1327  *      @handler: Function to be called when the IRQ occurs.
1328  *                Primary handler for threaded interrupts
1329  *                If NULL and thread_fn != NULL the default
1330  *                primary handler is installed
1331  *      @thread_fn: Function called from the irq handler thread
1332  *                  If NULL, no irq thread is created
1333  *      @irqflags: Interrupt type flags
1334  *      @devname: An ascii name for the claiming device
1335  *      @dev_id: A cookie passed back to the handler function
1336  *
1337  *      This call allocates interrupt resources and enables the
1338  *      interrupt line and IRQ handling. From the point this
1339  *      call is made your handler function may be invoked. Since
1340  *      your handler function must clear any interrupt the board
1341  *      raises, you must take care both to initialise your hardware
1342  *      and to set up the interrupt handler in the right order.
1343  *
1344  *      If you want to set up a threaded irq handler for your device
1345  *      then you need to supply @handler and @thread_fn. @handler is
1346  *      still called in hard interrupt context and has to check
1347  *      whether the interrupt originates from the device. If yes it
1348  *      needs to disable the interrupt on the device and return
1349  *      IRQ_WAKE_THREAD which will wake up the handler thread and run
1350  *      @thread_fn. This split handler design is necessary to support
1351  *      shared interrupts.
1352  *
1353  *      Dev_id must be globally unique. Normally the address of the
1354  *      device data structure is used as the cookie. Since the handler
1355  *      receives this value it makes sense to use it.
1356  *
1357  *      If your interrupt is shared you must pass a non NULL dev_id
1358  *      as this is required when freeing the interrupt.
1359  *
1360  *      Flags:
1361  *
1362  *      IRQF_SHARED             Interrupt is shared
1363  *      IRQF_SAMPLE_RANDOM      The interrupt can be used for entropy
1364  *      IRQF_TRIGGER_*          Specify active edge(s) or level
1365  *
1366  */
1367 int request_threaded_irq(unsigned int irq, irq_handler_t handler,
1368                          irq_handler_t thread_fn, unsigned long irqflags,
1369                          const char *devname, void *dev_id)
1370 {
1371         struct irqaction *action;
1372         struct irq_desc *desc;
1373         int retval;
1374
1375         /*
1376          * Sanity-check: shared interrupts must pass in a real dev-ID,
1377          * otherwise we'll have trouble later trying to figure out
1378          * which interrupt is which (messes up the interrupt freeing
1379          * logic etc).
1380          */
1381         if ((irqflags & IRQF_SHARED) && !dev_id)
1382                 return -EINVAL;
1383
1384         desc = irq_to_desc(irq);
1385         if (!desc)
1386                 return -EINVAL;
1387
1388         if (!irq_settings_can_request(desc) ||
1389             WARN_ON(irq_settings_is_per_cpu_devid(desc)))
1390                 return -EINVAL;
1391
1392         if (!handler) {
1393                 if (!thread_fn)
1394                         return -EINVAL;
1395                 handler = irq_default_primary_handler;
1396         }
1397
1398         action = kzalloc(sizeof(struct irqaction), GFP_KERNEL);
1399         if (!action)
1400                 return -ENOMEM;
1401
1402         action->handler = handler;
1403         action->thread_fn = thread_fn;
1404         action->flags = irqflags;
1405         action->name = devname;
1406         action->dev_id = dev_id;
1407
1408         chip_bus_lock(desc);
1409         retval = __setup_irq(irq, desc, action);
1410         chip_bus_sync_unlock(desc);
1411
1412         if (retval)
1413                 kfree(action);
1414
1415 #ifdef CONFIG_DEBUG_SHIRQ_FIXME
1416         if (!retval && (irqflags & IRQF_SHARED)) {
1417                 /*
1418                  * It's a shared IRQ -- the driver ought to be prepared for it
1419                  * to happen immediately, so let's make sure....
1420                  * We disable the irq to make sure that a 'real' IRQ doesn't
1421                  * run in parallel with our fake.
1422                  */
1423                 unsigned long flags;
1424
1425                 disable_irq(irq);
1426                 local_irq_save(flags);
1427
1428                 handler(irq, dev_id);
1429
1430                 local_irq_restore(flags);
1431                 enable_irq(irq);
1432         }
1433 #endif
1434         return retval;
1435 }
1436 EXPORT_SYMBOL(request_threaded_irq);
1437
1438 /**
1439  *      request_any_context_irq - allocate an interrupt line
1440  *      @irq: Interrupt line to allocate
1441  *      @handler: Function to be called when the IRQ occurs.
1442  *                Threaded handler for threaded interrupts.
1443  *      @flags: Interrupt type flags
1444  *      @name: An ascii name for the claiming device
1445  *      @dev_id: A cookie passed back to the handler function
1446  *
1447  *      This call allocates interrupt resources and enables the
1448  *      interrupt line and IRQ handling. It selects either a
1449  *      hardirq or threaded handling method depending on the
1450  *      context.
1451  *
1452  *      On failure, it returns a negative value. On success,
1453  *      it returns either IRQC_IS_HARDIRQ or IRQC_IS_NESTED.
1454  */
1455 int request_any_context_irq(unsigned int irq, irq_handler_t handler,
1456                             unsigned long flags, const char *name, void *dev_id)
1457 {
1458         struct irq_desc *desc = irq_to_desc(irq);
1459         int ret;
1460
1461         if (!desc)
1462                 return -EINVAL;
1463
1464         if (irq_settings_is_nested_thread(desc)) {
1465                 ret = request_threaded_irq(irq, NULL, handler,
1466                                            flags, name, dev_id);
1467                 return !ret ? IRQC_IS_NESTED : ret;
1468         }
1469
1470         ret = request_irq(irq, handler, flags, name, dev_id);
1471         return !ret ? IRQC_IS_HARDIRQ : ret;
1472 }
1473 EXPORT_SYMBOL_GPL(request_any_context_irq);
1474
1475 void enable_percpu_irq(unsigned int irq, unsigned int type)
1476 {
1477         unsigned int cpu = smp_processor_id();
1478         unsigned long flags;
1479         struct irq_desc *desc = irq_get_desc_lock(irq, &flags, IRQ_GET_DESC_CHECK_PERCPU);
1480
1481         if (!desc)
1482                 return;
1483
1484         type &= IRQ_TYPE_SENSE_MASK;
1485         if (type != IRQ_TYPE_NONE) {
1486                 int ret;
1487
1488                 ret = __irq_set_trigger(desc, irq, type);
1489
1490                 if (ret) {
1491                         WARN(1, "failed to set type for IRQ%d\n", irq);
1492                         goto out;
1493                 }
1494         }
1495
1496         irq_percpu_enable(desc, cpu);
1497 out:
1498         irq_put_desc_unlock(desc, flags);
1499 }
1500
1501 void disable_percpu_irq(unsigned int irq)
1502 {
1503         unsigned int cpu = smp_processor_id();
1504         unsigned long flags;
1505         struct irq_desc *desc = irq_get_desc_lock(irq, &flags, IRQ_GET_DESC_CHECK_PERCPU);
1506
1507         if (!desc)
1508                 return;
1509
1510         irq_percpu_disable(desc, cpu);
1511         irq_put_desc_unlock(desc, flags);
1512 }
1513
1514 /*
1515  * Internal function to unregister a percpu irqaction.
1516  */
1517 static struct irqaction *__free_percpu_irq(unsigned int irq, void __percpu *dev_id)
1518 {
1519         struct irq_desc *desc = irq_to_desc(irq);
1520         struct irqaction *action;
1521         unsigned long flags;
1522
1523         WARN(in_interrupt(), "Trying to free IRQ %d from IRQ context!\n", irq);
1524
1525         if (!desc)
1526                 return NULL;
1527
1528         raw_spin_lock_irqsave(&desc->lock, flags);
1529
1530         action = desc->action;
1531         if (!action || action->percpu_dev_id != dev_id) {
1532                 WARN(1, "Trying to free already-free IRQ %d\n", irq);
1533                 goto bad;
1534         }
1535
1536         if (!cpumask_empty(desc->percpu_enabled)) {
1537                 WARN(1, "percpu IRQ %d still enabled on CPU%d!\n",
1538                      irq, cpumask_first(desc->percpu_enabled));
1539                 goto bad;
1540         }
1541
1542         /* Found it - now remove it from the list of entries: */
1543         desc->action = NULL;
1544
1545         raw_spin_unlock_irqrestore(&desc->lock, flags);
1546
1547         unregister_handler_proc(irq, action);
1548
1549         module_put(desc->owner);
1550         return action;
1551
1552 bad:
1553         raw_spin_unlock_irqrestore(&desc->lock, flags);
1554         return NULL;
1555 }
1556
1557 /**
1558  *      remove_percpu_irq - free a per-cpu interrupt
1559  *      @irq: Interrupt line to free
1560  *      @act: irqaction for the interrupt
1561  *
1562  * Used to remove interrupts statically setup by the early boot process.
1563  */
1564 void remove_percpu_irq(unsigned int irq, struct irqaction *act)
1565 {
1566         struct irq_desc *desc = irq_to_desc(irq);
1567
1568         if (desc && irq_settings_is_per_cpu_devid(desc))
1569             __free_percpu_irq(irq, act->percpu_dev_id);
1570 }
1571
1572 /**
1573  *      free_percpu_irq - free an interrupt allocated with request_percpu_irq
1574  *      @irq: Interrupt line to free
1575  *      @dev_id: Device identity to free
1576  *
1577  *      Remove a percpu interrupt handler. The handler is removed, but
1578  *      the interrupt line is not disabled. This must be done on each
1579  *      CPU before calling this function. The function does not return
1580  *      until any executing interrupts for this IRQ have completed.
1581  *
1582  *      This function must not be called from interrupt context.
1583  */
1584 void free_percpu_irq(unsigned int irq, void __percpu *dev_id)
1585 {
1586         struct irq_desc *desc = irq_to_desc(irq);
1587
1588         if (!desc || !irq_settings_is_per_cpu_devid(desc))
1589                 return;
1590
1591         chip_bus_lock(desc);
1592         kfree(__free_percpu_irq(irq, dev_id));
1593         chip_bus_sync_unlock(desc);
1594 }
1595
1596 /**
1597  *      setup_percpu_irq - setup a per-cpu interrupt
1598  *      @irq: Interrupt line to setup
1599  *      @act: irqaction for the interrupt
1600  *
1601  * Used to statically setup per-cpu interrupts in the early boot process.
1602  */
1603 int setup_percpu_irq(unsigned int irq, struct irqaction *act)
1604 {
1605         struct irq_desc *desc = irq_to_desc(irq);
1606         int retval;
1607
1608         if (!desc || !irq_settings_is_per_cpu_devid(desc))
1609                 return -EINVAL;
1610         chip_bus_lock(desc);
1611         retval = __setup_irq(irq, desc, act);
1612         chip_bus_sync_unlock(desc);
1613
1614         return retval;
1615 }
1616
1617 /**
1618  *      request_percpu_irq - allocate a percpu interrupt line
1619  *      @irq: Interrupt line to allocate
1620  *      @handler: Function to be called when the IRQ occurs.
1621  *      @devname: An ascii name for the claiming device
1622  *      @dev_id: A percpu cookie passed back to the handler function
1623  *
1624  *      This call allocates interrupt resources, but doesn't
1625  *      automatically enable the interrupt. It has to be done on each
1626  *      CPU using enable_percpu_irq().
1627  *
1628  *      Dev_id must be globally unique. It is a per-cpu variable, and
1629  *      the handler gets called with the interrupted CPU's instance of
1630  *      that variable.
1631  */
1632 int request_percpu_irq(unsigned int irq, irq_handler_t handler,
1633                        const char *devname, void __percpu *dev_id)
1634 {
1635         struct irqaction *action;
1636         struct irq_desc *desc;
1637         int retval;
1638
1639         if (!dev_id)
1640                 return -EINVAL;
1641
1642         desc = irq_to_desc(irq);
1643         if (!desc || !irq_settings_can_request(desc) ||
1644             !irq_settings_is_per_cpu_devid(desc))
1645                 return -EINVAL;
1646
1647         action = kzalloc(sizeof(struct irqaction), GFP_KERNEL);
1648         if (!action)
1649                 return -ENOMEM;
1650
1651         action->handler = handler;
1652         action->flags = IRQF_PERCPU | IRQF_NO_SUSPEND;
1653         action->name = devname;
1654         action->percpu_dev_id = dev_id;
1655
1656         chip_bus_lock(desc);
1657         retval = __setup_irq(irq, desc, action);
1658         chip_bus_sync_unlock(desc);
1659
1660         if (retval)
1661                 kfree(action);
1662
1663         return retval;
1664 }