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 #define pr_fmt(fmt) "genirq: " fmt
  11
  12 #include <linux/irq.h>
  13 #include <linux/kthread.h>
  14 #include <linux/module.h>
  15 #include <linux/random.h>
  16 #include <linux/interrupt.h>
  17 #include <linux/slab.h>
  18 #include <linux/sched.h>
  19 #include <linux/task_work.h>
  20
  21 #include "internals.h"
  22
  23 #ifdef CONFIG_IRQ_FORCED_THREADING
  24 __read_mostly bool force_irqthreads;
  25
  26 static int __init setup_forced_irqthreads(char *arg)
  27 {
  28         force_irqthreads = true;
  29         return 0;
  30 }
  31 early_param("threadirqs", setup_forced_irqthreads);
  32 #endif
  33
  34 /**
  35  *      synchronize_irq - wait for pending IRQ handlers (on other CPUs)
  36  *      @irq: interrupt number to wait for
  37  *
  38  *      This function waits for any pending IRQ handlers for this interrupt
  39  *      to complete before returning. If you use this function while
  40  *      holding a resource the IRQ handler may need you will deadlock.
  41  *
  42  *      This function may be called - with care - from IRQ context.
  43  */
  44 void synchronize_irq(unsigned int irq)
  45 {
  46         struct irq_desc *desc = irq_to_desc(irq);
  47         bool inprogress;
  48
  49         if (!desc)
  50                 return;
  51
  52         do {
  53                 unsigned long flags;
  54
  55                 /*
  56                  * Wait until we're out of the critical section.  This might
  57                  * give the wrong answer due to the lack of memory barriers.
  58                  */
  59                 while (irqd_irq_inprogress(&desc->irq_data))
  60                         cpu_relax();
  61
  62                 /* Ok, that indicated we're done: double-check carefully. */
  63                 raw_spin_lock_irqsave(&desc->lock, flags);
  64                 inprogress = irqd_irq_inprogress(&desc->irq_data);
  65                 raw_spin_unlock_irqrestore(&desc->lock, flags);
  66
  67                 /* Oops, that failed? */
  68         } while (inprogress);
  69
  70         /*
  71          * We made sure that no hardirq handler is running. Now verify
  72          * that no threaded handlers are active.
  73          */
  74         wait_event(desc->wait_for_threads, !atomic_read(&desc->threads_active));
  75 }
  76 EXPORT_SYMBOL(synchronize_irq);
  77
  78 #ifdef CONFIG_SMP
  79 cpumask_var_t irq_default_affinity;
  80
  81 /**
  82  *      irq_can_set_affinity - Check if the affinity of a given irq can be set
  83  *      @irq:           Interrupt to check
  84  *
  85  */
  86 int irq_can_set_affinity(unsigned int irq)
  87 {
  88         struct irq_desc *desc = irq_to_desc(irq);
  89
  90         if (!desc || !irqd_can_balance(&desc->irq_data) ||
  91             !desc->irq_data.chip || !desc->irq_data.chip->irq_set_affinity)
  92                 return 0;
  93
  94         return 1;
  95 }
  96
  97 /**
  98  *      irq_set_thread_affinity - Notify irq threads to adjust affinity
  99  *      @desc:          irq descriptor which has affitnity changed
 100  *
 101  *      We just set IRQTF_AFFINITY and delegate the affinity setting
 102  *      to the interrupt thread itself. We can not call
 103  *      set_cpus_allowed_ptr() here as we hold desc->lock and this
 104  *      code can be called from hard interrupt context.
 105  */
 106 void irq_set_thread_affinity(struct irq_desc *desc)
 107 {
 108         struct irqaction *action = desc->action;
 109
 110         while (action) {
 111                 if (action->thread)
 112                         set_bit(IRQTF_AFFINITY, &action->thread_flags);
 113                 action = action->next;
 114         }
 115 }
 116
 117 #ifdef CONFIG_GENERIC_PENDING_IRQ
 118 static inline bool irq_can_move_pcntxt(struct irq_data *data)
 119 {
 120         return irqd_can_move_in_process_context(data);
 121 }
 122 static inline bool irq_move_pending(struct irq_data *data)
 123 {
 124         return irqd_is_setaffinity_pending(data);
 125 }
 126 static inline void
 127 irq_copy_pending(struct irq_desc *desc, const struct cpumask *mask)
 128 {
 129         cpumask_copy(desc->pending_mask, mask);
 130 }
 131 static inline void
 132 irq_get_pending(struct cpumask *mask, struct irq_desc *desc)
 133 {
 134         cpumask_copy(mask, desc->pending_mask);
 135 }
 136 #else
 137 static inline bool irq_can_move_pcntxt(struct irq_data *data) { return true; }
 138 static inline bool irq_move_pending(struct irq_data *data) { return false; }
 139 static inline void
 140 irq_copy_pending(struct irq_desc *desc, const struct cpumask *mask) { }
 141 static inline void
 142 irq_get_pending(struct cpumask *mask, struct irq_desc *desc) { }
 143 #endif
 144
 145 int __irq_set_affinity_locked(struct irq_data *data, const struct cpumask *mask)
 146 {
 147         struct irq_chip *chip = irq_data_get_irq_chip(data);
 148         struct irq_desc *desc = irq_data_to_desc(data);
 149         int ret = 0;
 150
 151         if (!chip || !chip->irq_set_affinity)
 152                 return -EINVAL;
 153
 154         if (irq_can_move_pcntxt(data)) {
 155                 ret = chip->irq_set_affinity(data, mask, false);
 156                 switch (ret) {
 157                 case IRQ_SET_MASK_OK:
 158                         cpumask_copy(data->affinity, mask);
 159                 case IRQ_SET_MASK_OK_NOCOPY:
 160                         irq_set_thread_affinity(desc);
 161                         ret = 0;
 162                 }
 163         } else {
 164                 irqd_set_move_pending(data);
 165                 irq_copy_pending(desc, mask);
 166         }
 167
 168         if (desc->affinity_notify) {
 169                 kref_get(&desc->affinity_notify->kref);
 170                 schedule_work(&desc->affinity_notify->work);
 171         }
 172         irqd_set(data, IRQD_AFFINITY_SET);
 173
 174         return ret;
 175 }
 176
 177 /**
 178  *      irq_set_affinity - Set the irq affinity of a given irq
 179  *      @irq:           Interrupt to set affinity
 180  *      @mask:          cpumask
 181  *
 182  */
 183 int irq_set_affinity(unsigned int irq, const struct cpumask *mask)
 184 {
 185         struct irq_desc *desc = irq_to_desc(irq);
 186         unsigned long flags;
 187         int ret;
 188
 189         if (!desc)
 190                 return -EINVAL;
 191
 192         raw_spin_lock_irqsave(&desc->lock, flags);
 193         ret =  __irq_set_affinity_locked(irq_desc_get_irq_data(desc), mask);
 194         raw_spin_unlock_irqrestore(&desc->lock, flags);
 195         return ret;
 196 }
 197
 198 int irq_set_affinity_hint(unsigned int irq, const struct cpumask *m)
 199 {
 200         unsigned long flags;
 201         struct irq_desc *desc = irq_get_desc_lock(irq, &flags, IRQ_GET_DESC_CHECK_GLOBAL);
 202
 203         if (!desc)
 204                 return -EINVAL;
 205         desc->affinity_hint = m;
 206         irq_put_desc_unlock(desc, flags);
 207         return 0;
 208 }
 209 EXPORT_SYMBOL_GPL(irq_set_affinity_hint);
 210
 211 static void irq_affinity_notify(struct work_struct *work)
 212 {
 213         struct irq_affinity_notify *notify =
 214                 container_of(work, struct irq_affinity_notify, work);
 215         struct irq_desc *desc = irq_to_desc(notify->irq);
 216         cpumask_var_t cpumask;
 217         unsigned long flags;
 218
 219         if (!desc || !alloc_cpumask_var(&cpumask, GFP_KERNEL))
 220                 goto out;
 221
 222         raw_spin_lock_irqsave(&desc->lock, flags);
 223         if (irq_move_pending(&desc->irq_data))
 224                 irq_get_pending(cpumask, desc);
 225         else
 226                 cpumask_copy(cpumask, desc->irq_data.affinity);
 227         raw_spin_unlock_irqrestore(&desc->lock, flags);
 228
 229         notify->notify(notify, cpumask);
 230
 231         free_cpumask_var(cpumask);
 232 out:
 233         kref_put(&notify->kref, notify->release);
 234 }
 235
 236 /**
 237  *      irq_set_affinity_notifier - control notification of IRQ affinity changes
 238  *      @irq:           Interrupt for which to enable/disable notification
 239  *      @notify:        Context for notification, or %NULL to disable
 240  *                      notification.  Function pointers must be initialised;
 241  *                      the other fields will be initialised by this function.
 242  *
 243  *      Must be called in process context.  Notification may only be enabled
 244  *      after the IRQ is allocated and must be disabled before the IRQ is
 245  *      freed using free_irq().
 246  */
 247 int
 248 irq_set_affinity_notifier(unsigned int irq, struct irq_affinity_notify *notify)
 249 {
 250         struct irq_desc *desc = irq_to_desc(irq);
 251         struct irq_affinity_notify *old_notify;
 252         unsigned long flags;
 253
 254         /* The release function is promised process context */
 255         might_sleep();
 256
 257         if (!desc)
 258                 return -EINVAL;
 259
 260         /* Complete initialisation of *notify */
 261         if (notify) {
 262                 notify->irq = irq;
 263                 kref_init(&notify->kref);
 264                 INIT_WORK(&notify->work, irq_affinity_notify);
 265         }
 266
 267         raw_spin_lock_irqsave(&desc->lock, flags);
 268         old_notify = desc->affinity_notify;
 269         desc->affinity_notify = notify;
 270         raw_spin_unlock_irqrestore(&desc->lock, flags);
 271
 272         if (old_notify)
 273                 kref_put(&old_notify->kref, old_notify->release);
 274
 275         return 0;
 276 }
 277 EXPORT_SYMBOL_GPL(irq_set_affinity_notifier);
 278
 279 #ifndef CONFIG_AUTO_IRQ_AFFINITY
 280 /*
 281  * Generic version of the affinity autoselector.
 282  */
 283 static int
 284 setup_affinity(unsigned int irq, struct irq_desc *desc, struct cpumask *mask)
 285 {
 286         struct irq_chip *chip = irq_desc_get_chip(desc);
 287         struct cpumask *set = irq_default_affinity;
 288         int ret, node = desc->irq_data.node;
 289
 290         /* Excludes PER_CPU and NO_BALANCE interrupts */
 291         if (!irq_can_set_affinity(irq))
 292                 return 0;
 293
 294         /*
 295          * Preserve an userspace affinity setup, but make sure that
 296          * one of the targets is online.
 297          */
 298         if (irqd_has_set(&desc->irq_data, IRQD_AFFINITY_SET)) {
 299                 if (cpumask_intersects(desc->irq_data.affinity,
 300                                        cpu_online_mask))
 301                         set = desc->irq_data.affinity;
 302                 else
 303                         irqd_clear(&desc->irq_data, IRQD_AFFINITY_SET);
 304         }
 305
 306         cpumask_and(mask, cpu_online_mask, set);
 307         if (node != NUMA_NO_NODE) {
 308                 const struct cpumask *nodemask = cpumask_of_node(node);
 309
 310                 /* make sure at least one of the cpus in nodemask is online */
 311                 if (cpumask_intersects(mask, nodemask))
 312                         cpumask_and(mask, mask, nodemask);
 313         }
 314         ret = chip->irq_set_affinity(&desc->irq_data, mask, false);
 315         switch (ret) {
 316         case IRQ_SET_MASK_OK:
 317                 cpumask_copy(desc->irq_data.affinity, mask);
 318         case IRQ_SET_MASK_OK_NOCOPY:
 319                 irq_set_thread_affinity(desc);
 320         }
 321         return 0;
 322 }
 323 #else
 324 static inline int
 325 setup_affinity(unsigned int irq, struct irq_desc *d, struct cpumask *mask)
 326 {
 327         return irq_select_affinity(irq);
 328 }
 329 #endif
 330
 331 /*
 332  * Called when affinity is set via /proc/irq
 333  */
 334 int irq_select_affinity_usr(unsigned int irq, struct cpumask *mask)
 335 {
 336         struct irq_desc *desc = irq_to_desc(irq);
 337         unsigned long flags;
 338         int ret;
 339
 340         raw_spin_lock_irqsave(&desc->lock, flags);
 341         ret = setup_affinity(irq, desc, mask);
 342         raw_spin_unlock_irqrestore(&desc->lock, flags);
 343         return ret;
 344 }
 345
 346 #else
 347 static inline int
 348 setup_affinity(unsigned int irq, struct irq_desc *desc, struct cpumask *mask)
 349 {
 350         return 0;
 351 }
 352 #endif
 353
 354 void __disable_irq(struct irq_desc *desc, unsigned int irq, bool suspend)
 355 {
 356         if (suspend) {
 357                 if (!desc->action || (desc->action->flags & IRQF_NO_SUSPEND))
 358                         return;
 359                 desc->istate |= IRQS_SUSPENDED;
 360         }
 361
 362         if (!desc->depth++)
 363                 irq_disable(desc);
 364 }
 365
 366 static int __disable_irq_nosync(unsigned int irq)
 367 {
 368         unsigned long flags;
 369         struct irq_desc *desc = irq_get_desc_buslock(irq, &flags, IRQ_GET_DESC_CHECK_GLOBAL);
 370
 371         if (!desc)
 372                 return -EINVAL;
 373         __disable_irq(desc, irq, false);
 374         irq_put_desc_busunlock(desc, flags);
 375         return 0;
 376 }
 377
 378 /**
 379  *      disable_irq_nosync - disable an irq without waiting
 380  *      @irq: Interrupt to disable
 381  *
 382  *      Disable the selected interrupt line.  Disables and Enables are
 383  *      nested.
 384  *      Unlike disable_irq(), this function does not ensure existing
 385  *      instances of the IRQ handler have completed before returning.
 386  *
 387  *      This function may be called from IRQ context.
 388  */
 389 void disable_irq_nosync(unsigned int irq)
 390 {
 391         __disable_irq_nosync(irq);
 392 }
 393 EXPORT_SYMBOL(disable_irq_nosync);
 394
 395 /**
 396  *      disable_irq - disable an irq and wait for completion
 397  *      @irq: Interrupt to disable
 398  *
 399  *      Disable the selected interrupt line.  Enables and Disables are
 400  *      nested.
 401  *      This function waits for any pending IRQ handlers for this interrupt
 402  *      to complete before returning. If you use this function while
 403  *      holding a resource the IRQ handler may need you will deadlock.
 404  *
 405  *      This function may be called - with care - from IRQ context.
 406  */
 407 void disable_irq(unsigned int irq)
 408 {
 409         if (!__disable_irq_nosync(irq))
 410                 synchronize_irq(irq);
 411 }
 412 EXPORT_SYMBOL(disable_irq);
 413
 414 void __enable_irq(struct irq_desc *desc, unsigned int irq, bool resume)
 415 {
 416         if (resume) {
 417                 if (!(desc->istate & IRQS_SUSPENDED)) {
 418                         if (!desc->action)
 419                                 return;
 420                         if (!(desc->action->flags & IRQF_FORCE_RESUME))
 421                                 return;
 422                         /* Pretend that it got disabled ! */
 423                         desc->depth++;
 424                 }
 425                 desc->istate &= ~IRQS_SUSPENDED;
 426         }
 427
 428         switch (desc->depth) {
 429         case 0:
 430  err_out:
 431                 WARN(1, KERN_WARNING "Unbalanced enable for IRQ %d\n", irq);
 432                 break;
 433         case 1: {
 434                 if (desc->istate & IRQS_SUSPENDED)
 435                         goto err_out;
 436                 /* Prevent probing on this irq: */
 437                 irq_settings_set_noprobe(desc);
 438                 irq_enable(desc);
 439                 check_irq_resend(desc, irq);
 440                 /* fall-through */
 441         }
 442         default:
 443                 desc->depth--;
 444         }
 445 }
 446
 447 /**
 448  *      enable_irq - enable handling of an irq
 449  *      @irq: Interrupt to enable
 450  *
 451  *      Undoes the effect of one call to disable_irq().  If this
 452  *      matches the last disable, processing of interrupts on this
 453  *      IRQ line is re-enabled.
 454  *
 455  *      This function may be called from IRQ context only when
 456  *      desc->irq_data.chip->bus_lock and desc->chip->bus_sync_unlock are NULL !
 457  */
 458 void enable_irq(unsigned int irq)
 459 {
 460         unsigned long flags;
 461         struct irq_desc *desc = irq_get_desc_buslock(irq, &flags, IRQ_GET_DESC_CHECK_GLOBAL);
 462
 463         if (!desc)
 464                 return;
 465         if (WARN(!desc->irq_data.chip,
 466                  KERN_ERR "enable_irq before setup/request_irq: irq %u\n", irq))
 467                 goto out;
 468
 469         __enable_irq(desc, irq, false);
 470 out:
 471         irq_put_desc_busunlock(desc, flags);
 472 }
 473 EXPORT_SYMBOL(enable_irq);
 474
 475 static int set_irq_wake_real(unsigned int irq, unsigned int on)
 476 {
 477         struct irq_desc *desc = irq_to_desc(irq);
 478         int ret = -ENXIO;
 479
 480         if (irq_desc_get_chip(desc)->flags &  IRQCHIP_SKIP_SET_WAKE)
 481                 return 0;
 482
 483         if (desc->irq_data.chip->irq_set_wake)
 484                 ret = desc->irq_data.chip->irq_set_wake(&desc->irq_data, on);
 485
 486         return ret;
 487 }
 488
 489 /**
 490  *      irq_set_irq_wake - control irq power management wakeup
 491  *      @irq:   interrupt to control
 492  *      @on:    enable/disable power management wakeup
 493  *
 494  *      Enable/disable power management wakeup mode, which is
 495  *      disabled by default.  Enables and disables must match,
 496  *      just as they match for non-wakeup mode support.
 497  *
 498  *      Wakeup mode lets this IRQ wake the system from sleep
 499  *      states like "suspend to RAM".
 500  */
 501 int irq_set_irq_wake(unsigned int irq, unsigned int on)
 502 {
 503         unsigned long flags;
 504         struct irq_desc *desc = irq_get_desc_buslock(irq, &flags, IRQ_GET_DESC_CHECK_GLOBAL);
 505         int ret = 0;
 506
 507         if (!desc)
 508                 return -EINVAL;
 509
 510         /* wakeup-capable irqs can be shared between drivers that
 511          * don't need to have the same sleep mode behaviors.
 512          */
 513         if (on) {
 514                 if (desc->wake_depth++ == 0) {
 515                         ret = set_irq_wake_real(irq, on);
 516                         if (ret)
 517                                 desc->wake_depth = 0;
 518                         else
 519                                 irqd_set(&desc->irq_data, IRQD_WAKEUP_STATE);
 520                 }
 521         } else {
 522                 if (desc->wake_depth == 0) {
 523                         WARN(1, "Unbalanced IRQ %d wake disable\n", irq);
 524                 } else if (--desc->wake_depth == 0) {
 525                         ret = set_irq_wake_real(irq, on);
 526                         if (ret)
 527                                 desc->wake_depth = 1;
 528                         else
 529                                 irqd_clear(&desc->irq_data, IRQD_WAKEUP_STATE);
 530                 }
 531         }
 532         irq_put_desc_busunlock(desc, flags);
 533         return ret;
 534 }
 535 EXPORT_SYMBOL(irq_set_irq_wake);
 536
 537 /*
 538  * Internal function that tells the architecture code whether a
 539  * particular irq has been exclusively allocated or is available
 540  * for driver use.
 541  */
 542 int can_request_irq(unsigned int irq, unsigned long irqflags)
 543 {
 544         unsigned long flags;
 545         struct irq_desc *desc = irq_get_desc_lock(irq, &flags, 0);
 546         int canrequest = 0;
 547
 548         if (!desc)
 549                 return 0;
 550
 551         if (irq_settings_can_request(desc)) {
 552                 if (desc->action)
 553                         if (irqflags & desc->action->flags & IRQF_SHARED)
 554                                 canrequest =1;
 555         }
 556         irq_put_desc_unlock(desc, flags);
 557         return canrequest;
 558 }
 559
 560 int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
 561                       unsigned long flags)
 562 {
 563         struct irq_chip *chip = desc->irq_data.chip;
 564         int ret, unmask = 0;
 565
 566         if (!chip || !chip->irq_set_type) {
 567                 /*
 568                  * IRQF_TRIGGER_* but the PIC does not support multiple
 569                  * flow-types?
 570                  */
 571                 pr_debug("No set_type function for IRQ %d (%s)\n", irq,
 572                          chip ? (chip->name ? : "unknown") : "unknown");
 573                 return 0;
 574         }
 575
 576         flags &= IRQ_TYPE_SENSE_MASK;
 577
 578         if (chip->flags & IRQCHIP_SET_TYPE_MASKED) {
 579                 if (!irqd_irq_masked(&desc->irq_data))
 580                         mask_irq(desc);
 581                 if (!irqd_irq_disabled(&desc->irq_data))
 582                         unmask = 1;
 583         }
 584
 585         /* caller masked out all except trigger mode flags */
 586         ret = chip->irq_set_type(&desc->irq_data, flags);
 587
 588         switch (ret) {
 589         case IRQ_SET_MASK_OK:
 590                 irqd_clear(&desc->irq_data, IRQD_TRIGGER_MASK);
 591                 irqd_set(&desc->irq_data, flags);
 592
 593         case IRQ_SET_MASK_OK_NOCOPY:
 594                 flags = irqd_get_trigger_type(&desc->irq_data);
 595                 irq_settings_set_trigger_mask(desc, flags);
 596                 irqd_clear(&desc->irq_data, IRQD_LEVEL);
 597                 irq_settings_clr_level(desc);
 598                 if (flags & IRQ_TYPE_LEVEL_MASK) {
 599                         irq_settings_set_level(desc);
 600                         irqd_set(&desc->irq_data, IRQD_LEVEL);
 601                 }
 602
 603                 ret = 0;
 604                 break;
 605         default:
 606                 pr_err("Setting trigger mode %lu for irq %u failed (%pF)\n",
 607                        flags, irq, chip->irq_set_type);
 608         }
 609         if (unmask)
 610                 unmask_irq(desc);
 611         return ret;
 612 }
 613
 614 /*
 615  * Default primary interrupt handler for threaded interrupts. Is
 616  * assigned as primary handler when request_threaded_irq is called
 617  * with handler == NULL. Useful for oneshot interrupts.
 618  */
 619 static irqreturn_t irq_default_primary_handler(int irq, void *dev_id)
 620 {
 621         return IRQ_WAKE_THREAD;
 622 }
 623
 624 /*
 625  * Primary handler for nested threaded interrupts. Should never be
 626  * called.
 627  */
 628 static irqreturn_t irq_nested_primary_handler(int irq, void *dev_id)
 629 {
 630         WARN(1, "Primary handler called for nested irq %d\n", irq);
 631         return IRQ_NONE;
 632 }
 633
 634 static int irq_wait_for_interrupt(struct irqaction *action)
 635 {
 636         set_current_state(TASK_INTERRUPTIBLE);
 637
 638         while (!kthread_should_stop()) {
 639
 640                 if (test_and_clear_bit(IRQTF_RUNTHREAD,
 641                                        &action->thread_flags)) {
 642                         __set_current_state(TASK_RUNNING);
 643                         return 0;
 644                 }
 645                 schedule();
 646                 set_current_state(TASK_INTERRUPTIBLE);
 647         }
 648         __set_current_state(TASK_RUNNING);
 649         return -1;
 650 }
 651
 652 /*
 653  * Oneshot interrupts keep the irq line masked until the threaded
 654  * handler finished. unmask if the interrupt has not been disabled and
 655  * is marked MASKED.
 656  */
 657 static void irq_finalize_oneshot(struct irq_desc *desc,
 658                                  struct irqaction *action)
 659 {
 660         if (!(desc->istate & IRQS_ONESHOT))
 661                 return;
 662 again:
 663         chip_bus_lock(desc);
 664         raw_spin_lock_irq(&desc->lock);
 665
 666         /*
 667          * Implausible though it may be we need to protect us against
 668          * the following scenario:
 669          *
 670          * The thread is faster done than the hard interrupt handler
 671          * on the other CPU. If we unmask the irq line then the
 672          * interrupt can come in again and masks the line, leaves due
 673          * to IRQS_INPROGRESS and the irq line is masked forever.
 674          *
 675          * This also serializes the state of shared oneshot handlers
 676          * versus "desc->threads_onehsot |= action->thread_mask;" in
 677          * irq_wake_thread(). See the comment there which explains the
 678          * serialization.
 679          */
 680         if (unlikely(irqd_irq_inprogress(&desc->irq_data))) {
 681                 raw_spin_unlock_irq(&desc->lock);
 682                 chip_bus_sync_unlock(desc);
 683                 cpu_relax();
 684                 goto again;
 685         }
 686
 687         /*
 688          * Now check again, whether the thread should run. Otherwise
 689          * we would clear the threads_oneshot bit of this thread which
 690          * was just set.
 691          */
 692         if (test_bit(IRQTF_RUNTHREAD, &action->thread_flags))
 693                 goto out_unlock;
 694
 695         desc->threads_oneshot &= ~action->thread_mask;
 696
 697         if (!desc->threads_oneshot && !irqd_irq_disabled(&desc->irq_data) &&
 698             irqd_irq_masked(&desc->irq_data))
 699                 unmask_irq(desc);
 700
 701 out_unlock:
 702         raw_spin_unlock_irq(&desc->lock);
 703         chip_bus_sync_unlock(desc);
 704 }
 705
 706 #ifdef CONFIG_SMP
 707 /*
 708  * Check whether we need to chasnge the affinity of the interrupt thread.
 709  */
 710 static void
 711 irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action)
 712 {
 713         cpumask_var_t mask;
 714
 715         if (!test_and_clear_bit(IRQTF_AFFINITY, &action->thread_flags))
 716                 return;
 717
 718         /*
 719          * In case we are out of memory we set IRQTF_AFFINITY again and
 720          * try again next time
 721          */
 722         if (!alloc_cpumask_var(&mask, GFP_KERNEL)) {
 723                 set_bit(IRQTF_AFFINITY, &action->thread_flags);
 724                 return;
 725         }
 726
 727         raw_spin_lock_irq(&desc->lock);
 728         cpumask_copy(mask, desc->irq_data.affinity);
 729         raw_spin_unlock_irq(&desc->lock);
 730
 731         set_cpus_allowed_ptr(current, mask);
 732         free_cpumask_var(mask);
 733 }
 734 #else
 735 static inline void
 736 irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action) { }
 737 #endif
 738
 739 /*
 740  * Interrupts which are not explicitely requested as threaded
 741  * interrupts rely on the implicit bh/preempt disable of the hard irq
 742  * context. So we need to disable bh here to avoid deadlocks and other
 743  * side effects.
 744  */
 745 static irqreturn_t
 746 irq_forced_thread_fn(struct irq_desc *desc, struct irqaction *action)
 747 {
 748         irqreturn_t ret;
 749
 750         local_bh_disable();
 751         ret = action->thread_fn(action->irq, action->dev_id);
 752         irq_finalize_oneshot(desc, action);
 753         local_bh_enable();
 754         return ret;
 755 }
 756
 757 /*
 758  * Interrupts explicitely requested as threaded interupts want to be
 759  * preemtible - many of them need to sleep and wait for slow busses to
 760  * complete.
 761  */
 762 static irqreturn_t irq_thread_fn(struct irq_desc *desc,
 763                 struct irqaction *action)
 764 {
 765         irqreturn_t ret;
 766
 767         ret = action->thread_fn(action->irq, action->dev_id);
 768         irq_finalize_oneshot(desc, action);
 769         return ret;
 770 }
 771
 772 static void wake_threads_waitq(struct irq_desc *desc)
 773 {
 774         if (atomic_dec_and_test(&desc->threads_active) &&
 775             waitqueue_active(&desc->wait_for_threads))
 776                 wake_up(&desc->wait_for_threads);
 777 }
 778
 779 static void irq_thread_dtor(struct task_work *unused)
 780 {
 781         struct task_struct *tsk = current;
 782         struct irq_desc *desc;
 783         struct irqaction *action;
 784
 785         if (WARN_ON_ONCE(!(current->flags & PF_EXITING)))
 786                 return;
 787
 788         action = kthread_data(tsk);
 789
 790         pr_err("exiting task \"%s\" (%d) is an active IRQ thread (irq %d)\n",
 791                tsk->comm ? tsk->comm : "", tsk->pid, action->irq);
 792
 793
 794         desc = irq_to_desc(action->irq);
 795         /*
 796          * If IRQTF_RUNTHREAD is set, we need to decrement
 797          * desc->threads_active and wake possible waiters.
 798          */
 799         if (test_and_clear_bit(IRQTF_RUNTHREAD, &action->thread_flags))
 800                 wake_threads_waitq(desc);
 801
 802         /* Prevent a stale desc->threads_oneshot */
 803         irq_finalize_oneshot(desc, action);
 804 }
 805
 806 /*
 807  * Interrupt handler thread
 808  */
 809 static int irq_thread(void *data)
 810 {
 811         struct task_work on_exit_work;
 812         static const struct sched_param param = {
 813                 .sched_priority = MAX_USER_RT_PRIO/2,
 814         };
 815         struct irqaction *action = data;
 816         struct irq_desc *desc = irq_to_desc(action->irq);
 817         irqreturn_t (*handler_fn)(struct irq_desc *desc,
 818                         struct irqaction *action);
 819
 820         if (force_irqthreads && test_bit(IRQTF_FORCED_THREAD,
 821                                         &action->thread_flags))
 822                 handler_fn = irq_forced_thread_fn;
 823         else
 824                 handler_fn = irq_thread_fn;
 825
 826         sched_setscheduler(current, SCHED_FIFO, &param);
 827
 828         init_task_work(&on_exit_work, irq_thread_dtor, NULL);
 829         task_work_add(current, &on_exit_work, false);
 830
 831         while (!irq_wait_for_interrupt(action)) {
 832                 irqreturn_t action_ret;
 833
 834                 irq_thread_check_affinity(desc, action);
 835
 836                 action_ret = handler_fn(desc, action);
 837                 if (!noirqdebug)
 838                         note_interrupt(action->irq, desc, action_ret);
 839
 840                 wake_threads_waitq(desc);
 841         }
 842
 843         /*
 844          * This is the regular exit path. __free_irq() is stopping the
 845          * thread via kthread_stop() after calling
 846          * synchronize_irq(). So neither IRQTF_RUNTHREAD nor the
 847          * oneshot mask bit can be set. We cannot verify that as we
 848          * cannot touch the oneshot mask at this point anymore as
 849          * __setup_irq() might have given out currents thread_mask
 850          * again.
 851          */
 852         task_work_cancel(current, irq_thread_dtor);
 853         return 0;
 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("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("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("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 }