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 #include <linux/task_work.h>
  18
  19 #include "internals.h"
  20
  21 #ifdef CONFIG_IRQ_FORCED_THREADING
  22 __read_mostly bool force_irqthreads;
  23
  24 static int __init setup_forced_irqthreads(char *arg)
  25 {
  26         force_irqthreads = true;
  27         return 0;
  28 }
  29 early_param("threadirqs", setup_forced_irqthreads);
  30 #endif
  31
  32 /**
  33  *      synchronize_irq - wait for pending IRQ handlers (on other CPUs)
  34  *      @irq: interrupt number to wait for
  35  *
  36  *      This function waits for any pending IRQ handlers for this interrupt
  37  *      to complete before returning. If you use this function while
  38  *      holding a resource the IRQ handler may need you will deadlock.
  39  *
  40  *      This function may be called - with care - from IRQ context.
  41  */
  42 void synchronize_irq(unsigned int irq)
  43 {
  44         struct irq_desc *desc = irq_to_desc(irq);
  45         bool inprogress;
  46
  47         if (!desc)
  48                 return;
  49
  50         do {
  51                 unsigned long flags;
  52
  53                 /*
  54                  * Wait until we're out of the critical section.  This might
  55                  * give the wrong answer due to the lack of memory barriers.
  56                  */
  57                 while (irqd_irq_inprogress(&desc->irq_data))
  58                         cpu_relax();
  59
  60                 /* Ok, that indicated we're done: double-check carefully. */
  61                 raw_spin_lock_irqsave(&desc->lock, flags);
  62                 inprogress = irqd_irq_inprogress(&desc->irq_data);
  63                 raw_spin_unlock_irqrestore(&desc->lock, flags);
  64
  65                 /* Oops, that failed? */
  66         } while (inprogress);
  67
  68         /*
  69          * We made sure that no hardirq handler is running. Now verify
  70          * that no threaded handlers are active.
  71          */
  72         wait_event(desc->wait_for_threads, !atomic_read(&desc->threads_active));
  73 }
  74 EXPORT_SYMBOL(synchronize_irq);
  75
  76 #ifdef CONFIG_SMP
  77 cpumask_var_t irq_default_affinity;
  78
  79 /**
  80  *      irq_can_set_affinity - Check if the affinity of a given irq can be set
  81  *      @irq:           Interrupt to check
  82  *
  83  */
  84 int irq_can_set_affinity(unsigned int irq)
  85 {
  86         struct irq_desc *desc = irq_to_desc(irq);
  87
  88         if (!desc || !irqd_can_balance(&desc->irq_data) ||
  89             !desc->irq_data.chip || !desc->irq_data.chip->irq_set_affinity)
  90                 return 0;
  91
  92         return 1;
  93 }
  94
  95 /**
  96  *      irq_set_thread_affinity - Notify irq threads to adjust affinity
  97  *      @desc:          irq descriptor which has affitnity changed
  98  *
  99  *      We just set IRQTF_AFFINITY and delegate the affinity setting
 100  *      to the interrupt thread itself. We can not call
 101  *      set_cpus_allowed_ptr() here as we hold desc->lock and this
 102  *      code can be called from hard interrupt context.
 103  */
 104 void irq_set_thread_affinity(struct irq_desc *desc)
 105 {
 106         struct irqaction *action = desc->action;
 107
 108         while (action) {
 109                 if (action->thread)
 110                         set_bit(IRQTF_AFFINITY, &action->thread_flags);
 111                 action = action->next;
 112         }
 113 }
 114
 115 #ifdef CONFIG_GENERIC_PENDING_IRQ
 116 static inline bool irq_can_move_pcntxt(struct irq_data *data)
 117 {
 118         return irqd_can_move_in_process_context(data);
 119 }
 120 static inline bool irq_move_pending(struct irq_data *data)
 121 {
 122         return irqd_is_setaffinity_pending(data);
 123 }
 124 static inline void
 125 irq_copy_pending(struct irq_desc *desc, const struct cpumask *mask)
 126 {
 127         cpumask_copy(desc->pending_mask, mask);
 128 }
 129 static inline void
 130 irq_get_pending(struct cpumask *mask, struct irq_desc *desc)
 131 {
 132         cpumask_copy(mask, desc->pending_mask);
 133 }
 134 #else
 135 static inline bool irq_can_move_pcntxt(struct irq_data *data) { return true; }
 136 static inline bool irq_move_pending(struct irq_data *data) { return false; }
 137 static inline void
 138 irq_copy_pending(struct irq_desc *desc, const struct cpumask *mask) { }
 139 static inline void
 140 irq_get_pending(struct cpumask *mask, struct irq_desc *desc) { }
 141 #endif
 142
 143 int __irq_set_affinity_locked(struct irq_data *data, const struct cpumask *mask)
 144 {
 145         struct irq_chip *chip = irq_data_get_irq_chip(data);
 146         struct irq_desc *desc = irq_data_to_desc(data);
 147         int ret = 0;
 148
 149         if (!chip || !chip->irq_set_affinity)
 150                 return -EINVAL;
 151
 152         if (irq_can_move_pcntxt(data)) {
 153                 ret = chip->irq_set_affinity(data, mask, false);
 154                 switch (ret) {
 155                 case IRQ_SET_MASK_OK:
 156                         cpumask_copy(data->affinity, mask);
 157                 case IRQ_SET_MASK_OK_NOCOPY:
 158                         irq_set_thread_affinity(desc);
 159                         ret = 0;
 160                 }
 161         } else {
 162                 irqd_set_move_pending(data);
 163                 irq_copy_pending(desc, mask);
 164         }
 165
 166         if (desc->affinity_notify) {
 167                 kref_get(&desc->affinity_notify->kref);
 168                 schedule_work(&desc->affinity_notify->work);
 169         }
 170         irqd_set(data, IRQD_AFFINITY_SET);
 171
 172         return ret;
 173 }
 174
 175 /**
 176  *      irq_set_affinity - Set the irq affinity of a given irq
 177  *      @irq:           Interrupt to set affinity
 178  *      @mask:          cpumask
 179  *
 180  */
 181 int irq_set_affinity(unsigned int irq, const struct cpumask *mask)
 182 {
 183         struct irq_desc *desc = irq_to_desc(irq);
 184         unsigned long flags;
 185         int ret;
 186
 187         if (!desc)
 188                 return -EINVAL;
 189
 190         raw_spin_lock_irqsave(&desc->lock, flags);
 191         ret =  __irq_set_affinity_locked(irq_desc_get_irq_data(desc), mask);
 192         raw_spin_unlock_irqrestore(&desc->lock, flags);
 193         return ret;
 194 }
 195
 196 int irq_set_affinity_hint(unsigned int irq, const struct cpumask *m)
 197 {
 198         unsigned long flags;
 199         struct irq_desc *desc = irq_get_desc_lock(irq, &flags, IRQ_GET_DESC_CHECK_GLOBAL);
 200
 201         if (!desc)
 202                 return -EINVAL;
 203         desc->affinity_hint = m;
 204         irq_put_desc_unlock(desc, flags);
 205         return 0;
 206 }
 207 EXPORT_SYMBOL_GPL(irq_set_affinity_hint);
 208
 209 static void irq_affinity_notify(struct work_struct *work)
 210 {
 211         struct irq_affinity_notify *notify =
 212                 container_of(work, struct irq_affinity_notify, work);
 213         struct irq_desc *desc = irq_to_desc(notify->irq);
 214         cpumask_var_t cpumask;
 215         unsigned long flags;
 216
 217         if (!desc || !alloc_cpumask_var(&cpumask, GFP_KERNEL))
 218                 goto out;
 219
 220         raw_spin_lock_irqsave(&desc->lock, flags);
 221         if (irq_move_pending(&desc->irq_data))
 222                 irq_get_pending(cpumask, desc);
 223         else
 224                 cpumask_copy(cpumask, desc->irq_data.affinity);
 225         raw_spin_unlock_irqrestore(&desc->lock, flags);
 226
 227         notify->notify(notify, cpumask);
 228
 229         free_cpumask_var(cpumask);
 230 out:
 231         kref_put(&notify->kref, notify->release);
 232 }
 233
 234 /**
 235  *      irq_set_affinity_notifier - control notification of IRQ affinity changes
 236  *      @irq:           Interrupt for which to enable/disable notification
 237  *      @notify:        Context for notification, or %NULL to disable
 238  *                      notification.  Function pointers must be initialised;
 239  *                      the other fields will be initialised by this function.
 240  *
 241  *      Must be called in process context.  Notification may only be enabled
 242  *      after the IRQ is allocated and must be disabled before the IRQ is
 243  *      freed using free_irq().
 244  */
 245 int
 246 irq_set_affinity_notifier(unsigned int irq, struct irq_affinity_notify *notify)
 247 {
 248         struct irq_desc *desc = irq_to_desc(irq);
 249         struct irq_affinity_notify *old_notify;
 250         unsigned long flags;
 251
 252         /* The release function is promised process context */
 253         might_sleep();
 254
 255         if (!desc)
 256                 return -EINVAL;
 257
 258         /* Complete initialisation of *notify */
 259         if (notify) {
 260                 notify->irq = irq;
 261                 kref_init(&notify->kref);
 262                 INIT_WORK(&notify->work, irq_affinity_notify);
 263         }
 264
 265         raw_spin_lock_irqsave(&desc->lock, flags);
 266         old_notify = desc->affinity_notify;
 267         desc->affinity_notify = notify;
 268         raw_spin_unlock_irqrestore(&desc->lock, flags);
 269
 270         if (old_notify)
 271                 kref_put(&old_notify->kref, old_notify->release);
 272
 273         return 0;
 274 }
 275 EXPORT_SYMBOL_GPL(irq_set_affinity_notifier);
 276
 277 #ifndef CONFIG_AUTO_IRQ_AFFINITY
 278 /*
 279  * Generic version of the affinity autoselector.
 280  */
 281 static int
 282 setup_affinity(unsigned int irq, struct irq_desc *desc, struct cpumask *mask)
 283 {
 284         struct irq_chip *chip = irq_desc_get_chip(desc);
 285         struct cpumask *set = irq_default_affinity;
 286         int ret, node = desc->irq_data.node;
 287
 288         /* Excludes PER_CPU and NO_BALANCE interrupts */
 289         if (!irq_can_set_affinity(irq))
 290                 return 0;
 291
 292         /*
 293          * Preserve an userspace affinity setup, but make sure that
 294          * one of the targets is online.
 295          */
 296         if (irqd_has_set(&desc->irq_data, IRQD_AFFINITY_SET)) {
 297                 if (cpumask_intersects(desc->irq_data.affinity,
 298                                        cpu_online_mask))
 299                         set = desc->irq_data.affinity;
 300                 else
 301                         irqd_clear(&desc->irq_data, IRQD_AFFINITY_SET);
 302         }
 303
 304         cpumask_and(mask, cpu_online_mask, set);
 305         if (node != NUMA_NO_NODE) {
 306                 const struct cpumask *nodemask = cpumask_of_node(node);
 307
 308                 /* make sure at least one of the cpus in nodemask is online */
 309                 if (cpumask_intersects(mask, nodemask))
 310                         cpumask_and(mask, mask, nodemask);
 311         }
 312         ret = chip->irq_set_affinity(&desc->irq_data, mask, false);
 313         switch (ret) {
 314         case IRQ_SET_MASK_OK:
 315                 cpumask_copy(desc->irq_data.affinity, mask);
 316         case IRQ_SET_MASK_OK_NOCOPY:
 317                 irq_set_thread_affinity(desc);
 318         }
 319         return 0;
 320 }
 321 #else
 322 static inline int
 323 setup_affinity(unsigned int irq, struct irq_desc *d, struct cpumask *mask)
 324 {
 325         return irq_select_affinity(irq);
 326 }
 327 #endif
 328
 329 /*
 330  * Called when affinity is set via /proc/irq
 331  */
 332 int irq_select_affinity_usr(unsigned int irq, struct cpumask *mask)
 333 {
 334         struct irq_desc *desc = irq_to_desc(irq);
 335         unsigned long flags;
 336         int ret;
 337
 338         raw_spin_lock_irqsave(&desc->lock, flags);
 339         ret = setup_affinity(irq, desc, mask);
 340         raw_spin_unlock_irqrestore(&desc->lock, flags);
 341         return ret;
 342 }
 343
 344 #else
 345 static inline int
 346 setup_affinity(unsigned int irq, struct irq_desc *desc, struct cpumask *mask)
 347 {
 348         return 0;
 349 }
 350 #endif
 351
 352 void __disable_irq(struct irq_desc *desc, unsigned int irq, bool suspend)
 353 {
 354         if (suspend) {
 355                 if (!desc->action || (desc->action->flags & IRQF_NO_SUSPEND))
 356                         return;
 357                 desc->istate |= IRQS_SUSPENDED;
 358         }
 359
 360         if (!desc->depth++)
 361                 irq_disable(desc);
 362 }
 363
 364 static int __disable_irq_nosync(unsigned int irq)
 365 {
 366         unsigned long flags;
 367         struct irq_desc *desc = irq_get_desc_buslock(irq, &flags, IRQ_GET_DESC_CHECK_GLOBAL);
 368
 369         if (!desc)
 370                 return -EINVAL;
 371         __disable_irq(desc, irq, false);
 372         irq_put_desc_busunlock(desc, flags);
 373         return 0;
 374 }
 375
 376 /**
 377  *      disable_irq_nosync - disable an irq without waiting
 378  *      @irq: Interrupt to disable
 379  *
 380  *      Disable the selected interrupt line.  Disables and Enables are
 381  *      nested.
 382  *      Unlike disable_irq(), this function does not ensure existing
 383  *      instances of the IRQ handler have completed before returning.
 384  *
 385  *      This function may be called from IRQ context.
 386  */
 387 void disable_irq_nosync(unsigned int irq)
 388 {
 389         __disable_irq_nosync(irq);
 390 }
 391 EXPORT_SYMBOL(disable_irq_nosync);
 392
 393 /**
 394  *      disable_irq - disable an irq and wait for completion
 395  *      @irq: Interrupt to disable
 396  *
 397  *      Disable the selected interrupt line.  Enables and Disables are
 398  *      nested.
 399  *      This function waits for any pending IRQ handlers for this interrupt
 400  *      to complete before returning. If you use this function while
 401  *      holding a resource the IRQ handler may need you will deadlock.
 402  *
 403  *      This function may be called - with care - from IRQ context.
 404  */
 405 void disable_irq(unsigned int irq)
 406 {
 407         if (!__disable_irq_nosync(irq))
 408                 synchronize_irq(irq);
 409 }
 410 EXPORT_SYMBOL(disable_irq);
 411
 412 void __enable_irq(struct irq_desc *desc, unsigned int irq, bool resume)
 413 {
 414         if (resume) {
 415                 if (!(desc->istate & IRQS_SUSPENDED)) {
 416                         if (!desc->action)
 417                                 return;
 418                         if (!(desc->action->flags & IRQF_FORCE_RESUME))
 419                                 return;
 420                         /* Pretend that it got disabled ! */
 421                         desc->depth++;
 422                 }
 423                 desc->istate &= ~IRQS_SUSPENDED;
 424         }
 425
 426         switch (desc->depth) {
 427         case 0:
 428  err_out:
 429                 WARN(1, KERN_WARNING "Unbalanced enable for IRQ %d\n", irq);
 430                 break;
 431         case 1: {
 432                 if (desc->istate & IRQS_SUSPENDED)
 433                         goto err_out;
 434                 /* Prevent probing on this irq: */
 435                 irq_settings_set_noprobe(desc);
 436                 irq_enable(desc);
 437                 check_irq_resend(desc, irq);
 438                 /* fall-through */
 439         }
 440         default:
 441                 desc->depth--;
 442         }
 443 }
 444
 445 /**
 446  *      enable_irq - enable handling of an irq
 447  *      @irq: Interrupt to enable
 448  *
 449  *      Undoes the effect of one call to disable_irq().  If this
 450  *      matches the last disable, processing of interrupts on this
 451  *      IRQ line is re-enabled.
 452  *
 453  *      This function may be called from IRQ context only when
 454  *      desc->irq_data.chip->bus_lock and desc->chip->bus_sync_unlock are NULL !
 455  */
 456 void enable_irq(unsigned int irq)
 457 {
 458         unsigned long flags;
 459         struct irq_desc *desc = irq_get_desc_buslock(irq, &flags, IRQ_GET_DESC_CHECK_GLOBAL);
 460
 461         if (!desc)
 462                 return;
 463         if (WARN(!desc->irq_data.chip,
 464                  KERN_ERR "enable_irq before setup/request_irq: irq %u\n", irq))
 465                 goto out;
 466
 467         __enable_irq(desc, irq, false);
 468 out:
 469         irq_put_desc_busunlock(desc, flags);
 470 }
 471 EXPORT_SYMBOL(enable_irq);
 472
 473 static int set_irq_wake_real(unsigned int irq, unsigned int on)
 474 {
 475         struct irq_desc *desc = irq_to_desc(irq);
 476         int ret = -ENXIO;
 477
 478         if (irq_desc_get_chip(desc)->flags &  IRQCHIP_SKIP_SET_WAKE)
 479                 return 0;
 480
 481         if (desc->irq_data.chip->irq_set_wake)
 482                 ret = desc->irq_data.chip->irq_set_wake(&desc->irq_data, on);
 483
 484         return ret;
 485 }
 486
 487 /**
 488  *      irq_set_irq_wake - control irq power management wakeup
 489  *      @irq:   interrupt to control
 490  *      @on:    enable/disable power management wakeup
 491  *
 492  *      Enable/disable power management wakeup mode, which is
 493  *      disabled by default.  Enables and disables must match,
 494  *      just as they match for non-wakeup mode support.
 495  *
 496  *      Wakeup mode lets this IRQ wake the system from sleep
 497  *      states like "suspend to RAM".
 498  */
 499 int irq_set_irq_wake(unsigned int irq, unsigned int on)
 500 {
 501         unsigned long flags;
 502         struct irq_desc *desc = irq_get_desc_buslock(irq, &flags, IRQ_GET_DESC_CHECK_GLOBAL);
 503         int ret = 0;
 504
 505         if (!desc)
 506                 return -EINVAL;
 507
 508         /* wakeup-capable irqs can be shared between drivers that
 509          * don't need to have the same sleep mode behaviors.
 510          */
 511         if (on) {
 512                 if (desc->wake_depth++ == 0) {
 513                         ret = set_irq_wake_real(irq, on);
 514                         if (ret)
 515                                 desc->wake_depth = 0;
 516                         else
 517                                 irqd_set(&desc->irq_data, IRQD_WAKEUP_STATE);
 518                 }
 519         } else {
 520                 if (desc->wake_depth == 0) {
 521                         WARN(1, "Unbalanced IRQ %d wake disable\n", irq);
 522                 } else if (--desc->wake_depth == 0) {
 523                         ret = set_irq_wake_real(irq, on);
 524                         if (ret)
 525                                 desc->wake_depth = 1;
 526                         else
 527                                 irqd_clear(&desc->irq_data, IRQD_WAKEUP_STATE);
 528                 }
 529         }
 530         irq_put_desc_busunlock(desc, flags);
 531         return ret;
 532 }
 533 EXPORT_SYMBOL(irq_set_irq_wake);
 534
 535 /*
 536  * Internal function that tells the architecture code whether a
 537  * particular irq has been exclusively allocated or is available
 538  * for driver use.
 539  */
 540 int can_request_irq(unsigned int irq, unsigned long irqflags)
 541 {
 542         unsigned long flags;
 543         struct irq_desc *desc = irq_get_desc_lock(irq, &flags, 0);
 544         int canrequest = 0;
 545
 546         if (!desc)
 547                 return 0;
 548
 549         if (irq_settings_can_request(desc)) {
 550                 if (desc->action)
 551                         if (irqflags & desc->action->flags & IRQF_SHARED)
 552                                 canrequest =1;
 553         }
 554         irq_put_desc_unlock(desc, flags);
 555         return canrequest;
 556 }
 557
 558 int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
 559                       unsigned long flags)
 560 {
 561         struct irq_chip *chip = desc->irq_data.chip;
 562         int ret, unmask = 0;
 563
 564         if (!chip || !chip->irq_set_type) {
 565                 /*
 566                  * IRQF_TRIGGER_* but the PIC does not support multiple
 567                  * flow-types?
 568                  */
 569                 pr_debug("genirq: No set_type function for IRQ %d (%s)\n", irq,
 570                          chip ? (chip->name ? : "unknown") : "unknown");
 571                 return 0;
 572         }
 573
 574         flags &= IRQ_TYPE_SENSE_MASK;
 575
 576         if (chip->flags & IRQCHIP_SET_TYPE_MASKED) {
 577                 if (!irqd_irq_masked(&desc->irq_data))
 578                         mask_irq(desc);
 579                 if (!irqd_irq_disabled(&desc->irq_data))
 580                         unmask = 1;
 581         }
 582
 583         /* caller masked out all except trigger mode flags */
 584         ret = chip->irq_set_type(&desc->irq_data, flags);
 585
 586         switch (ret) {
 587         case IRQ_SET_MASK_OK:
 588                 irqd_clear(&desc->irq_data, IRQD_TRIGGER_MASK);
 589                 irqd_set(&desc->irq_data, flags);
 590
 591         case IRQ_SET_MASK_OK_NOCOPY:
 592                 flags = irqd_get_trigger_type(&desc->irq_data);
 593                 irq_settings_set_trigger_mask(desc, flags);
 594                 irqd_clear(&desc->irq_data, IRQD_LEVEL);
 595                 irq_settings_clr_level(desc);
 596                 if (flags & IRQ_TYPE_LEVEL_MASK) {
 597                         irq_settings_set_level(desc);
 598                         irqd_set(&desc->irq_data, IRQD_LEVEL);
 599                 }
 600
 601                 ret = 0;
 602                 break;
 603         default:
 604                 pr_err("genirq: Setting trigger mode %lu for irq %u failed (%pF)\n",
 605                        flags, irq, chip->irq_set_type);
 606         }
 607         if (unmask)
 608                 unmask_irq(desc);
 609         return ret;
 610 }
 611
 612 /*
 613  * Default primary interrupt handler for threaded interrupts. Is
 614  * assigned as primary handler when request_threaded_irq is called
 615  * with handler == NULL. Useful for oneshot interrupts.
 616  */
 617 static irqreturn_t irq_default_primary_handler(int irq, void *dev_id)
 618 {
 619         return IRQ_WAKE_THREAD;
 620 }
 621
 622 /*
 623  * Primary handler for nested threaded interrupts. Should never be
 624  * called.
 625  */
 626 static irqreturn_t irq_nested_primary_handler(int irq, void *dev_id)
 627 {
 628         WARN(1, "Primary handler called for nested irq %d\n", irq);
 629         return IRQ_NONE;
 630 }
 631
 632 static int irq_wait_for_interrupt(struct irqaction *action)
 633 {
 634         set_current_state(TASK_INTERRUPTIBLE);
 635
 636         while (!kthread_should_stop()) {
 637
 638                 if (test_and_clear_bit(IRQTF_RUNTHREAD,
 639                                        &action->thread_flags)) {
 640                         __set_current_state(TASK_RUNNING);
 641                         return 0;
 642                 }
 643                 schedule();
 644                 set_current_state(TASK_INTERRUPTIBLE);
 645         }
 646         __set_current_state(TASK_RUNNING);
 647         return -1;
 648 }
 649
 650 /*
 651  * Oneshot interrupts keep the irq line masked until the threaded
 652  * handler finished. unmask if the interrupt has not been disabled and
 653  * is marked MASKED.
 654  */
 655 static void irq_finalize_oneshot(struct irq_desc *desc,
 656                                  struct irqaction *action)
 657 {
 658         if (!(desc->istate & IRQS_ONESHOT))
 659                 return;
 660 again:
 661         chip_bus_lock(desc);
 662         raw_spin_lock_irq(&desc->lock);
 663
 664         /*
 665          * Implausible though it may be we need to protect us against
 666          * the following scenario:
 667          *
 668          * The thread is faster done than the hard interrupt handler
 669          * on the other CPU. If we unmask the irq line then the
 670          * interrupt can come in again and masks the line, leaves due
 671          * to IRQS_INPROGRESS and the irq line is masked forever.
 672          *
 673          * This also serializes the state of shared oneshot handlers
 674          * versus "desc->threads_onehsot |= action->thread_mask;" in
 675          * irq_wake_thread(). See the comment there which explains the
 676          * serialization.
 677          */
 678         if (unlikely(irqd_irq_inprogress(&desc->irq_data))) {
 679                 raw_spin_unlock_irq(&desc->lock);
 680                 chip_bus_sync_unlock(desc);
 681                 cpu_relax();
 682                 goto again;
 683         }
 684
 685         /*
 686          * Now check again, whether the thread should run. Otherwise
 687          * we would clear the threads_oneshot bit of this thread which
 688          * was just set.
 689          */
 690         if (test_bit(IRQTF_RUNTHREAD, &action->thread_flags))
 691                 goto out_unlock;
 692
 693         desc->threads_oneshot &= ~action->thread_mask;
 694
 695         if (!desc->threads_oneshot && !irqd_irq_disabled(&desc->irq_data) &&
 696             irqd_irq_masked(&desc->irq_data))
 697                 unmask_irq(desc);
 698
 699 out_unlock:
 700         raw_spin_unlock_irq(&desc->lock);
 701         chip_bus_sync_unlock(desc);
 702 }
 703
 704 #ifdef CONFIG_SMP
 705 /*
 706  * Check whether we need to chasnge the affinity of the interrupt thread.
 707  */
 708 static void
 709 irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action)
 710 {
 711         cpumask_var_t mask;
 712
 713         if (!test_and_clear_bit(IRQTF_AFFINITY, &action->thread_flags))
 714                 return;
 715
 716         /*
 717          * In case we are out of memory we set IRQTF_AFFINITY again and
 718          * try again next time
 719          */
 720         if (!alloc_cpumask_var(&mask, GFP_KERNEL)) {
 721                 set_bit(IRQTF_AFFINITY, &action->thread_flags);
 722                 return;
 723         }
 724
 725         raw_spin_lock_irq(&desc->lock);
 726         cpumask_copy(mask, desc->irq_data.affinity);
 727         raw_spin_unlock_irq(&desc->lock);
 728
 729         set_cpus_allowed_ptr(current, mask);
 730         free_cpumask_var(mask);
 731 }
 732 #else
 733 static inline void
 734 irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action) { }
 735 #endif
 736
 737 /*
 738  * Interrupts which are not explicitely requested as threaded
 739  * interrupts rely on the implicit bh/preempt disable of the hard irq
 740  * context. So we need to disable bh here to avoid deadlocks and other
 741  * side effects.
 742  */
 743 static irqreturn_t
 744 irq_forced_thread_fn(struct irq_desc *desc, struct irqaction *action)
 745 {
 746         irqreturn_t ret;
 747
 748         local_bh_disable();
 749         ret = action->thread_fn(action->irq, action->dev_id);
 750         irq_finalize_oneshot(desc, action);
 751         local_bh_enable();
 752         return ret;
 753 }
 754
 755 /*
 756  * Interrupts explicitely requested as threaded interupts want to be
 757  * preemtible - many of them need to sleep and wait for slow busses to
 758  * complete.
 759  */
 760 static irqreturn_t irq_thread_fn(struct irq_desc *desc,
 761                 struct irqaction *action)
 762 {
 763         irqreturn_t ret;
 764
 765         ret = action->thread_fn(action->irq, action->dev_id);
 766         irq_finalize_oneshot(desc, action);
 767         return ret;
 768 }
 769
 770 static void wake_threads_waitq(struct irq_desc *desc)
 771 {
 772         if (atomic_dec_and_test(&desc->threads_active) &&
 773             waitqueue_active(&desc->wait_for_threads))
 774                 wake_up(&desc->wait_for_threads);
 775 }
 776
 777 static void irq_thread_dtor(struct task_work *unused)
 778 {
 779         struct task_struct *tsk = current;
 780         struct irq_desc *desc;
 781         struct irqaction *action;
 782
 783         if (WARN_ON_ONCE(!(current->flags & PF_EXITING)))
 784                 return;
 785
 786         action = kthread_data(tsk);
 787
 788         pr_err("genirq: exiting task \"%s\" (%d) is an active IRQ thread (irq %d)\n",
 789                tsk->comm ? tsk->comm : "", tsk->pid, action->irq);
 790
 791
 792         desc = irq_to_desc(action->irq);
 793         /*
 794          * If IRQTF_RUNTHREAD is set, we need to decrement
 795          * desc->threads_active and wake possible waiters.
 796          */
 797         if (test_and_clear_bit(IRQTF_RUNTHREAD, &action->thread_flags))
 798                 wake_threads_waitq(desc);
 799
 800         /* Prevent a stale desc->threads_oneshot */
 801         irq_finalize_oneshot(desc, action);
 802 }
 803
 804 /*
 805  * Interrupt handler thread
 806  */
 807 static int irq_thread(void *data)
 808 {
 809         struct task_work on_exit_work;
 810         static const struct sched_param param = {
 811                 .sched_priority = MAX_USER_RT_PRIO/2,
 812         };
 813         struct irqaction *action = data;
 814         struct irq_desc *desc = irq_to_desc(action->irq);
 815         irqreturn_t (*handler_fn)(struct irq_desc *desc,
 816                         struct irqaction *action);
 817
 818         if (force_irqthreads && test_bit(IRQTF_FORCED_THREAD,
 819                                         &action->thread_flags))
 820                 handler_fn = irq_forced_thread_fn;
 821         else
 822                 handler_fn = irq_thread_fn;
 823
 824         sched_setscheduler(current, SCHED_FIFO, &param);
 825
 826         init_task_work(&on_exit_work, irq_thread_dtor, NULL);
 827         task_work_add(current, &on_exit_work, false);
 828
 829         while (!irq_wait_for_interrupt(action)) {
 830                 irqreturn_t action_ret;
 831
 832                 irq_thread_check_affinity(desc, action);
 833
 834                 action_ret = handler_fn(desc, action);
 835                 if (!noirqdebug)
 836                         note_interrupt(action->irq, desc, action_ret);
 837
 838                 wake_threads_waitq(desc);
 839         }
 840
 841         /*
 842          * This is the regular exit path. __free_irq() is stopping the
 843          * thread via kthread_stop() after calling
 844          * synchronize_irq(). So neither IRQTF_RUNTHREAD nor the
 845          * oneshot mask bit can be set. We cannot verify that as we
 846          * cannot touch the oneshot mask at this point anymore as
 847          * __setup_irq() might have given out currents thread_mask
 848          * again.
 849          */
 850         task_work_cancel(current, irq_thread_dtor);
 851         return 0;
 852 }
 853
 854 static void irq_setup_forced_threading(struct irqaction *new)
 855 {
 856         if (!force_irqthreads)
 857                 return;
 858         if (new->flags & (IRQF_NO_THREAD | IRQF_PERCPU | IRQF_ONESHOT))
 859                 return;
 860
 861         new->flags |= IRQF_ONESHOT;
 862
 863         if (!new->thread_fn) {
 864                 set_bit(IRQTF_FORCED_THREAD, &new->thread_flags);
 865                 new->thread_fn = new->handler;
 866                 new->handler = irq_default_primary_handler;
 867         }
 868 }
 869
 870 /*
 871  * Internal function to register an irqaction - typically used to
 872  * allocate special interrupts that are part of the architecture.
 873  */
 874 static int
 875 __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
 876 {
 877         struct irqaction *old, **old_ptr;
 878         unsigned long flags, thread_mask = 0;
 879         int ret, nested, shared = 0;
 880         cpumask_var_t mask;
 881
 882         if (!desc)
 883                 return -EINVAL;
 884
 885         if (desc->irq_data.chip == &no_irq_chip)
 886                 return -ENOSYS;
 887         if (!try_module_get(desc->owner))
 888                 return -ENODEV;
 889         /*
 890          * Some drivers like serial.c use request_irq() heavily,
 891          * so we have to be careful not to interfere with a
 892          * running system.
 893          */
 894         if (new->flags & IRQF_SAMPLE_RANDOM) {
 895                 /*
 896                  * This function might sleep, we want to call it first,
 897                  * outside of the atomic block.
 898                  * Yes, this might clear the entropy pool if the wrong
 899                  * driver is attempted to be loaded, without actually
 900                  * installing a new handler, but is this really a problem,
 901                  * only the sysadmin is able to do this.
 902                  */
 903                 rand_initialize_irq(irq);
 904         }
 905
 906         /*
 907          * Check whether the interrupt nests into another interrupt
 908          * thread.
 909          */
 910         nested = irq_settings_is_nested_thread(desc);
 911         if (nested) {
 912                 if (!new->thread_fn) {
 913                         ret = -EINVAL;
 914                         goto out_mput;
 915                 }
 916                 /*
 917                  * Replace the primary handler which was provided from
 918                  * the driver for non nested interrupt handling by the
 919                  * dummy function which warns when called.
 920                  */
 921                 new->handler = irq_nested_primary_handler;
 922         } else {
 923                 if (irq_settings_can_thread(desc))
 924                         irq_setup_forced_threading(new);
 925         }
 926
 927         /*
 928          * Create a handler thread when a thread function is supplied
 929          * and the interrupt does not nest into another interrupt
 930          * thread.
 931          */
 932         if (new->thread_fn && !nested) {
 933                 struct task_struct *t;
 934
 935                 t = kthread_create(irq_thread, new, "irq/%d-%s", irq,
 936                                    new->name);
 937                 if (IS_ERR(t)) {
 938                         ret = PTR_ERR(t);
 939                         goto out_mput;
 940                 }
 941                 /*
 942                  * We keep the reference to the task struct even if
 943                  * the thread dies to avoid that the interrupt code
 944                  * references an already freed task_struct.
 945                  */
 946                 get_task_struct(t);
 947                 new->thread = t;
 948         }
 949
 950         if (!alloc_cpumask_var(&mask, GFP_KERNEL)) {
 951                 ret = -ENOMEM;
 952                 goto out_thread;
 953         }
 954
 955         /*
 956          * The following block of code has to be executed atomically
 957          */
 958         raw_spin_lock_irqsave(&desc->lock, flags);
 959         old_ptr = &desc->action;
 960         old = *old_ptr;
 961         if (old) {
 962                 /*
 963                  * Can't share interrupts unless both agree to and are
 964                  * the same type (level, edge, polarity). So both flag
 965                  * fields must have IRQF_SHARED set and the bits which
 966                  * set the trigger type must match. Also all must
 967                  * agree on ONESHOT.
 968                  */
 969                 if (!((old->flags & new->flags) & IRQF_SHARED) ||
 970                     ((old->flags ^ new->flags) & IRQF_TRIGGER_MASK) ||
 971                     ((old->flags ^ new->flags) & IRQF_ONESHOT))
 972                         goto mismatch;
 973
 974                 /* All handlers must agree on per-cpuness */
 975                 if ((old->flags & IRQF_PERCPU) !=
 976                     (new->flags & IRQF_PERCPU))
 977                         goto mismatch;
 978
 979                 /* add new interrupt at end of irq queue */
 980                 do {
 981                         /*
 982                          * Or all existing action->thread_mask bits,
 983                          * so we can find the next zero bit for this
 984                          * new action.
 985                          */
 986                         thread_mask |= old->thread_mask;
 987                         old_ptr = &old->next;
 988                         old = *old_ptr;
 989                 } while (old);
 990                 shared = 1;
 991         }
 992
 993         /*
 994          * Setup the thread mask for this irqaction for ONESHOT. For
 995          * !ONESHOT irqs the thread mask is 0 so we can avoid a
 996          * conditional in irq_wake_thread().
 997          */
 998         if (new->flags & IRQF_ONESHOT) {
 999                 /*
1000                  * Unlikely to have 32 resp 64 irqs sharing one line,
1001                  * but who knows.
1002                  */
1003                 if (thread_mask == ~0UL) {
1004                         ret = -EBUSY;
1005                         goto out_mask;
1006                 }
1007                 /*
1008                  * The thread_mask for the action is or'ed to
1009                  * desc->thread_active to indicate that the
1010                  * IRQF_ONESHOT thread handler has been woken, but not
1011                  * yet finished. The bit is cleared when a thread
1012                  * completes. When all threads of a shared interrupt
1013                  * line have completed desc->threads_active becomes
1014                  * zero and the interrupt line is unmasked. See
1015                  * handle.c:irq_wake_thread() for further information.
1016                  *
1017                  * If no thread is woken by primary (hard irq context)
1018                  * interrupt handlers, then desc->threads_active is
1019                  * also checked for zero to unmask the irq line in the
1020                  * affected hard irq flow handlers
1021                  * (handle_[fasteoi|level]_irq).
1022                  *
1023                  * The new action gets the first zero bit of
1024                  * thread_mask assigned. See the loop above which or's
1025                  * all existing action->thread_mask bits.
1026                  */
1027                 new->thread_mask = 1 << ffz(thread_mask);
1028
1029         } else if (new->handler == irq_default_primary_handler) {
1030                 /*
1031                  * The interrupt was requested with handler = NULL, so
1032                  * we use the default primary handler for it. But it
1033                  * does not have the oneshot flag set. In combination
1034                  * with level interrupts this is deadly, because the
1035                  * default primary handler just wakes the thread, then
1036                  * the irq lines is reenabled, but the device still
1037                  * has the level irq asserted. Rinse and repeat....
1038                  *
1039                  * While this works for edge type interrupts, we play
1040                  * it safe and reject unconditionally because we can't
1041                  * say for sure which type this interrupt really
1042                  * has. The type flags are unreliable as the
1043                  * underlying chip implementation can override them.
1044                  */
1045                 pr_err("genirq: Threaded irq requested with handler=NULL and !ONESHOT for irq %d\n",
1046                        irq);
1047                 ret = -EINVAL;
1048                 goto out_mask;
1049         }
1050
1051         if (!shared) {
1052                 init_waitqueue_head(&desc->wait_for_threads);
1053
1054                 /* Setup the type (level, edge polarity) if configured: */
1055                 if (new->flags & IRQF_TRIGGER_MASK) {
1056                         ret = __irq_set_trigger(desc, irq,
1057                                         new->flags & IRQF_TRIGGER_MASK);
1058
1059                         if (ret)
1060                                 goto out_mask;
1061                 }
1062
1063                 desc->istate &= ~(IRQS_AUTODETECT | IRQS_SPURIOUS_DISABLED | \
1064                                   IRQS_ONESHOT | IRQS_WAITING);
1065                 irqd_clear(&desc->irq_data, IRQD_IRQ_INPROGRESS);
1066
1067                 if (new->flags & IRQF_PERCPU) {
1068                         irqd_set(&desc->irq_data, IRQD_PER_CPU);
1069                         irq_settings_set_per_cpu(desc);
1070                 }
1071
1072                 if (new->flags & IRQF_ONESHOT)
1073                         desc->istate |= IRQS_ONESHOT;
1074
1075                 if (irq_settings_can_autoenable(desc))
1076                         irq_startup(desc, true);
1077                 else
1078                         /* Undo nested disables: */
1079                         desc->depth = 1;
1080
1081                 /* Exclude IRQ from balancing if requested */
1082                 if (new->flags & IRQF_NOBALANCING) {
1083                         irq_settings_set_no_balancing(desc);
1084                         irqd_set(&desc->irq_data, IRQD_NO_BALANCING);
1085                 }
1086
1087                 /* Set default affinity mask once everything is setup */
1088                 setup_affinity(irq, desc, mask);
1089
1090         } else if (new->flags & IRQF_TRIGGER_MASK) {
1091                 unsigned int nmsk = new->flags & IRQF_TRIGGER_MASK;
1092                 unsigned int omsk = irq_settings_get_trigger_mask(desc);
1093
1094                 if (nmsk != omsk)
1095                         /* hope the handler works with current  trigger mode */
1096                         pr_warning("genirq: irq %d uses trigger mode %u; requested %u\n",
1097                                    irq, nmsk, omsk);
1098         }
1099
1100         new->irq = irq;
1101         *old_ptr = new;
1102
1103         /* Reset broken irq detection when installing new handler */
1104         desc->irq_count = 0;
1105         desc->irqs_unhandled = 0;
1106
1107         /*
1108          * Check whether we disabled the irq via the spurious handler
1109          * before. Reenable it and give it another chance.
1110          */
1111         if (shared && (desc->istate & IRQS_SPURIOUS_DISABLED)) {
1112                 desc->istate &= ~IRQS_SPURIOUS_DISABLED;
1113                 __enable_irq(desc, irq, false);
1114         }
1115
1116         raw_spin_unlock_irqrestore(&desc->lock, flags);
1117
1118         /*
1119          * Strictly no need to wake it up, but hung_task complains
1120          * when no hard interrupt wakes the thread up.
1121          */
1122         if (new->thread)
1123                 wake_up_process(new->thread);
1124
1125         register_irq_proc(irq, desc);
1126         new->dir = NULL;
1127         register_handler_proc(irq, new);
1128         free_cpumask_var(mask);
1129
1130         return 0;
1131
1132 mismatch:
1133         if (!(new->flags & IRQF_PROBE_SHARED)) {
1134                 pr_err("genirq: Flags mismatch irq %d. %08x (%s) vs. %08x (%s)\n",
1135                        irq, new->flags, new->name, old->flags, old->name);
1136 #ifdef CONFIG_DEBUG_SHIRQ
1137                 dump_stack();
1138 #endif
1139         }
1140         ret = -EBUSY;
1141
1142 out_mask:
1143         raw_spin_unlock_irqrestore(&desc->lock, flags);
1144         free_cpumask_var(mask);
1145
1146 out_thread:
1147         if (new->thread) {
1148                 struct task_struct *t = new->thread;
1149
1150                 new->thread = NULL;
1151                 kthread_stop(t);
1152                 put_task_struct(t);
1153         }
1154 out_mput:
1155         module_put(desc->owner);
1156         return ret;
1157 }
1158
1159 /**
1160  *      setup_irq - setup an interrupt
1161  *      @irq: Interrupt line to setup
1162  *      @act: irqaction for the interrupt
1163  *
1164  * Used to statically setup interrupts in the early boot process.
1165  */
1166 int setup_irq(unsigned int irq, struct irqaction *act)
1167 {
1168         int retval;
1169         struct irq_desc *desc = irq_to_desc(irq);
1170
1171         if (WARN_ON(irq_settings_is_per_cpu_devid(desc)))
1172                 return -EINVAL;
1173         chip_bus_lock(desc);
1174         retval = __setup_irq(irq, desc, act);
1175         chip_bus_sync_unlock(desc);
1176
1177         return retval;
1178 }
1179 EXPORT_SYMBOL_GPL(setup_irq);
1180
1181 /*
1182  * Internal function to unregister an irqaction - used to free
1183  * regular and special interrupts that are part of the architecture.
1184  */
1185 static struct irqaction *__free_irq(unsigned int irq, void *dev_id)
1186 {
1187         struct irq_desc *desc = irq_to_desc(irq);
1188         struct irqaction *action, **action_ptr;
1189         unsigned long flags;
1190
1191         WARN(in_interrupt(), "Trying to free IRQ %d from IRQ context!\n", irq);
1192
1193         if (!desc)
1194                 return NULL;
1195
1196         raw_spin_lock_irqsave(&desc->lock, flags);
1197
1198         /*
1199          * There can be multiple actions per IRQ descriptor, find the right
1200          * one based on the dev_id:
1201          */
1202         action_ptr = &desc->action;
1203         for (;;) {
1204                 action = *action_ptr;
1205
1206                 if (!action) {
1207                         WARN(1, "Trying to free already-free IRQ %d\n", irq);
1208                         raw_spin_unlock_irqrestore(&desc->lock, flags);
1209
1210                         return NULL;
1211                 }
1212
1213                 if (action->dev_id == dev_id)
1214                         break;
1215                 action_ptr = &action->next;
1216         }
1217
1218         /* Found it - now remove it from the list of entries: */
1219         *action_ptr = action->next;
1220
1221         /* If this was the last handler, shut down the IRQ line: */
1222         if (!desc->action)
1223                 irq_shutdown(desc);
1224
1225 #ifdef CONFIG_SMP
1226         /* make sure affinity_hint is cleaned up */
1227         if (WARN_ON_ONCE(desc->affinity_hint))
1228                 desc->affinity_hint = NULL;
1229 #endif
1230
1231         raw_spin_unlock_irqrestore(&desc->lock, flags);
1232
1233         unregister_handler_proc(irq, action);
1234
1235         /* Make sure it's not being used on another CPU: */
1236         synchronize_irq(irq);
1237
1238 #ifdef CONFIG_DEBUG_SHIRQ
1239         /*
1240          * It's a shared IRQ -- the driver ought to be prepared for an IRQ
1241          * event to happen even now it's being freed, so let's make sure that
1242          * is so by doing an extra call to the handler ....
1243          *
1244          * ( We do this after actually deregistering it, to make sure that a
1245          *   'real' IRQ doesn't run in * parallel with our fake. )
1246          */
1247         if (action->flags & IRQF_SHARED) {
1248                 local_irq_save(flags);
1249                 action->handler(irq, dev_id);
1250                 local_irq_restore(flags);
1251         }
1252 #endif
1253
1254         if (action->thread) {
1255                 kthread_stop(action->thread);
1256                 put_task_struct(action->thread);
1257         }
1258
1259         module_put(desc->owner);
1260         return action;
1261 }
1262
1263 /**
1264  *      remove_irq - free an interrupt
1265  *      @irq: Interrupt line to free
1266  *      @act: irqaction for the interrupt
1267  *
1268  * Used to remove interrupts statically setup by the early boot process.
1269  */
1270 void remove_irq(unsigned int irq, struct irqaction *act)
1271 {
1272         struct irq_desc *desc = irq_to_desc(irq);
1273
1274         if (desc && !WARN_ON(irq_settings_is_per_cpu_devid(desc)))
1275             __free_irq(irq, act->dev_id);
1276 }
1277 EXPORT_SYMBOL_GPL(remove_irq);
1278
1279 /**
1280  *      free_irq - free an interrupt allocated with request_irq
1281  *      @irq: Interrupt line to free
1282  *      @dev_id: Device identity to free
1283  *
1284  *      Remove an interrupt handler. The handler is removed and if the
1285  *      interrupt line is no longer in use by any driver it is disabled.
1286  *      On a shared IRQ the caller must ensure the interrupt is disabled
1287  *      on the card it drives before calling this function. The function
1288  *      does not return until any executing interrupts for this IRQ
1289  *      have completed.
1290  *
1291  *      This function must not be called from interrupt context.
1292  */
1293 void free_irq(unsigned int irq, void *dev_id)
1294 {
1295         struct irq_desc *desc = irq_to_desc(irq);
1296
1297         if (!desc || WARN_ON(irq_settings_is_per_cpu_devid(desc)))
1298                 return;
1299
1300 #ifdef CONFIG_SMP
1301         if (WARN_ON(desc->affinity_notify))
1302                 desc->affinity_notify = NULL;
1303 #endif
1304
1305         chip_bus_lock(desc);
1306         kfree(__free_irq(irq, dev_id));
1307         chip_bus_sync_unlock(desc);
1308 }
1309 EXPORT_SYMBOL(free_irq);
1310
1311 /**
1312  *      request_threaded_irq - allocate an interrupt line
1313  *      @irq: Interrupt line to allocate
1314  *      @handler: Function to be called when the IRQ occurs.
1315  *                Primary handler for threaded interrupts
1316  *                If NULL and thread_fn != NULL the default
1317  *                primary handler is installed
1318  *      @thread_fn: Function called from the irq handler thread
1319  *                  If NULL, no irq thread is created
1320  *      @irqflags: Interrupt type flags
1321  *      @devname: An ascii name for the claiming device
1322  *      @dev_id: A cookie passed back to the handler function
1323  *
1324  *      This call allocates interrupt resources and enables the
1325  *      interrupt line and IRQ handling. From the point this
1326  *      call is made your handler function may be invoked. Since
1327  *      your handler function must clear any interrupt the board
1328  *      raises, you must take care both to initialise your hardware
1329  *      and to set up the interrupt handler in the right order.
1330  *
1331  *      If you want to set up a threaded irq handler for your device
1332  *      then you need to supply @handler and @thread_fn. @handler is
1333  *      still called in hard interrupt context and has to check
1334  *      whether the interrupt originates from the device. If yes it
1335  *      needs to disable the interrupt on the device and return
1336  *      IRQ_WAKE_THREAD which will wake up the handler thread and run
1337  *      @thread_fn. This split handler design is necessary to support
1338  *      shared interrupts.
1339  *
1340  *      Dev_id must be globally unique. Normally the address of the
1341  *      device data structure is used as the cookie. Since the handler
1342  *      receives this value it makes sense to use it.
1343  *
1344  *      If your interrupt is shared you must pass a non NULL dev_id
1345  *      as this is required when freeing the interrupt.
1346  *
1347  *      Flags:
1348  *
1349  *      IRQF_SHARED             Interrupt is shared
1350  *      IRQF_SAMPLE_RANDOM      The interrupt can be used for entropy
1351  *      IRQF_TRIGGER_*          Specify active edge(s) or level
1352  *
1353  */
1354 int request_threaded_irq(unsigned int irq, irq_handler_t handler,
1355                          irq_handler_t thread_fn, unsigned long irqflags,
1356                          const char *devname, void *dev_id)
1357 {
1358         struct irqaction *action;
1359         struct irq_desc *desc;
1360         int retval;
1361
1362         /*
1363          * Sanity-check: shared interrupts must pass in a real dev-ID,
1364          * otherwise we'll have trouble later trying to figure out
1365          * which interrupt is which (messes up the interrupt freeing
1366          * logic etc).
1367          */
1368         if ((irqflags & IRQF_SHARED) && !dev_id)
1369                 return -EINVAL;
1370
1371         desc = irq_to_desc(irq);
1372         if (!desc)
1373                 return -EINVAL;
1374
1375         if (!irq_settings_can_request(desc) ||
1376             WARN_ON(irq_settings_is_per_cpu_devid(desc)))
1377                 return -EINVAL;
1378
1379         if (!handler) {
1380                 if (!thread_fn)
1381                         return -EINVAL;
1382                 handler = irq_default_primary_handler;
1383         }
1384
1385         action = kzalloc(sizeof(struct irqaction), GFP_KERNEL);
1386         if (!action)
1387                 return -ENOMEM;
1388
1389         action->handler = handler;
1390         action->thread_fn = thread_fn;
1391         action->flags = irqflags;
1392         action->name = devname;
1393         action->dev_id = dev_id;
1394
1395         chip_bus_lock(desc);
1396         retval = __setup_irq(irq, desc, action);
1397         chip_bus_sync_unlock(desc);
1398
1399         if (retval)
1400                 kfree(action);
1401
1402 #ifdef CONFIG_DEBUG_SHIRQ_FIXME
1403         if (!retval && (irqflags & IRQF_SHARED)) {
1404                 /*
1405                  * It's a shared IRQ -- the driver ought to be prepared for it
1406                  * to happen immediately, so let's make sure....
1407                  * We disable the irq to make sure that a 'real' IRQ doesn't
1408                  * run in parallel with our fake.
1409                  */
1410                 unsigned long flags;
1411
1412                 disable_irq(irq);
1413                 local_irq_save(flags);
1414
1415                 handler(irq, dev_id);
1416
1417                 local_irq_restore(flags);
1418                 enable_irq(irq);
1419         }
1420 #endif
1421         return retval;
1422 }
1423 EXPORT_SYMBOL(request_threaded_irq);
1424
1425 /**
1426  *      request_any_context_irq - allocate an interrupt line
1427  *      @irq: Interrupt line to allocate
1428  *      @handler: Function to be called when the IRQ occurs.
1429  *                Threaded handler for threaded interrupts.
1430  *      @flags: Interrupt type flags
1431  *      @name: An ascii name for the claiming device
1432  *      @dev_id: A cookie passed back to the handler function
1433  *
1434  *      This call allocates interrupt resources and enables the
1435  *      interrupt line and IRQ handling. It selects either a
1436  *      hardirq or threaded handling method depending on the
1437  *      context.
1438  *
1439  *      On failure, it returns a negative value. On success,
1440  *      it returns either IRQC_IS_HARDIRQ or IRQC_IS_NESTED.
1441  */
1442 int request_any_context_irq(unsigned int irq, irq_handler_t handler,
1443                             unsigned long flags, const char *name, void *dev_id)
1444 {
1445         struct irq_desc *desc = irq_to_desc(irq);
1446         int ret;
1447
1448         if (!desc)
1449                 return -EINVAL;
1450
1451         if (irq_settings_is_nested_thread(desc)) {
1452                 ret = request_threaded_irq(irq, NULL, handler,
1453                                            flags, name, dev_id);
1454                 return !ret ? IRQC_IS_NESTED : ret;
1455         }
1456
1457         ret = request_irq(irq, handler, flags, name, dev_id);
1458         return !ret ? IRQC_IS_HARDIRQ : ret;
1459 }
1460 EXPORT_SYMBOL_GPL(request_any_context_irq);
1461
1462 void enable_percpu_irq(unsigned int irq, unsigned int type)
1463 {
1464         unsigned int cpu = smp_processor_id();
1465         unsigned long flags;
1466         struct irq_desc *desc = irq_get_desc_lock(irq, &flags, IRQ_GET_DESC_CHECK_PERCPU);
1467
1468         if (!desc)
1469                 return;
1470
1471         type &= IRQ_TYPE_SENSE_MASK;
1472         if (type != IRQ_TYPE_NONE) {
1473                 int ret;
1474
1475                 ret = __irq_set_trigger(desc, irq, type);
1476
1477                 if (ret) {
1478                         WARN(1, "failed to set type for IRQ%d\n", irq);
1479                         goto out;
1480                 }
1481         }
1482
1483         irq_percpu_enable(desc, cpu);
1484 out:
1485         irq_put_desc_unlock(desc, flags);
1486 }
1487
1488 void disable_percpu_irq(unsigned int irq)
1489 {
1490         unsigned int cpu = smp_processor_id();
1491         unsigned long flags;
1492         struct irq_desc *desc = irq_get_desc_lock(irq, &flags, IRQ_GET_DESC_CHECK_PERCPU);
1493
1494         if (!desc)
1495                 return;
1496
1497         irq_percpu_disable(desc, cpu);
1498         irq_put_desc_unlock(desc, flags);
1499 }
1500
1501 /*
1502  * Internal function to unregister a percpu irqaction.
1503  */
1504 static struct irqaction *__free_percpu_irq(unsigned int irq, void __percpu *dev_id)
1505 {
1506         struct irq_desc *desc = irq_to_desc(irq);
1507         struct irqaction *action;
1508         unsigned long flags;
1509
1510         WARN(in_interrupt(), "Trying to free IRQ %d from IRQ context!\n", irq);
1511
1512         if (!desc)
1513                 return NULL;
1514
1515         raw_spin_lock_irqsave(&desc->lock, flags);
1516
1517         action = desc->action;
1518         if (!action || action->percpu_dev_id != dev_id) {
1519                 WARN(1, "Trying to free already-free IRQ %d\n", irq);
1520                 goto bad;
1521         }
1522
1523         if (!cpumask_empty(desc->percpu_enabled)) {
1524                 WARN(1, "percpu IRQ %d still enabled on CPU%d!\n",
1525                      irq, cpumask_first(desc->percpu_enabled));
1526                 goto bad;
1527         }
1528
1529         /* Found it - now remove it from the list of entries: */
1530         desc->action = NULL;
1531
1532         raw_spin_unlock_irqrestore(&desc->lock, flags);
1533
1534         unregister_handler_proc(irq, action);
1535
1536         module_put(desc->owner);
1537         return action;
1538
1539 bad:
1540         raw_spin_unlock_irqrestore(&desc->lock, flags);
1541         return NULL;
1542 }
1543
1544 /**
1545  *      remove_percpu_irq - free a per-cpu interrupt
1546  *      @irq: Interrupt line to free
1547  *      @act: irqaction for the interrupt
1548  *
1549  * Used to remove interrupts statically setup by the early boot process.
1550  */
1551 void remove_percpu_irq(unsigned int irq, struct irqaction *act)
1552 {
1553         struct irq_desc *desc = irq_to_desc(irq);
1554
1555         if (desc && irq_settings_is_per_cpu_devid(desc))
1556             __free_percpu_irq(irq, act->percpu_dev_id);
1557 }
1558
1559 /**
1560  *      free_percpu_irq - free an interrupt allocated with request_percpu_irq
1561  *      @irq: Interrupt line to free
1562  *      @dev_id: Device identity to free
1563  *
1564  *      Remove a percpu interrupt handler. The handler is removed, but
1565  *      the interrupt line is not disabled. This must be done on each
1566  *      CPU before calling this function. The function does not return
1567  *      until any executing interrupts for this IRQ have completed.
1568  *
1569  *      This function must not be called from interrupt context.
1570  */
1571 void free_percpu_irq(unsigned int irq, void __percpu *dev_id)
1572 {
1573         struct irq_desc *desc = irq_to_desc(irq);
1574
1575         if (!desc || !irq_settings_is_per_cpu_devid(desc))
1576                 return;
1577
1578         chip_bus_lock(desc);
1579         kfree(__free_percpu_irq(irq, dev_id));
1580         chip_bus_sync_unlock(desc);
1581 }
1582
1583 /**
1584  *      setup_percpu_irq - setup a per-cpu interrupt
1585  *      @irq: Interrupt line to setup
1586  *      @act: irqaction for the interrupt
1587  *
1588  * Used to statically setup per-cpu interrupts in the early boot process.
1589  */
1590 int setup_percpu_irq(unsigned int irq, struct irqaction *act)
1591 {
1592         struct irq_desc *desc = irq_to_desc(irq);
1593         int retval;
1594
1595         if (!desc || !irq_settings_is_per_cpu_devid(desc))
1596                 return -EINVAL;
1597         chip_bus_lock(desc);
1598         retval = __setup_irq(irq, desc, act);
1599         chip_bus_sync_unlock(desc);
1600
1601         return retval;
1602 }
1603
1604 /**
1605  *      request_percpu_irq - allocate a percpu interrupt line
1606  *      @irq: Interrupt line to allocate
1607  *      @handler: Function to be called when the IRQ occurs.
1608  *      @devname: An ascii name for the claiming device
1609  *      @dev_id: A percpu cookie passed back to the handler function
1610  *
1611  *      This call allocates interrupt resources, but doesn't
1612  *      automatically enable the interrupt. It has to be done on each
1613  *      CPU using enable_percpu_irq().
1614  *
1615  *      Dev_id must be globally unique. It is a per-cpu variable, and
1616  *      the handler gets called with the interrupted CPU's instance of
1617  *      that variable.
1618  */
1619 int request_percpu_irq(unsigned int irq, irq_handler_t handler,
1620                        const char *devname, void __percpu *dev_id)
1621 {
1622         struct irqaction *action;
1623         struct irq_desc *desc;
1624         int retval;
1625
1626         if (!dev_id)
1627                 return -EINVAL;
1628
1629         desc = irq_to_desc(irq);
1630         if (!desc || !irq_settings_can_request(desc) ||
1631             !irq_settings_is_per_cpu_devid(desc))
1632                 return -EINVAL;
1633
1634         action = kzalloc(sizeof(struct irqaction), GFP_KERNEL);
1635         if (!action)
1636                 return -ENOMEM;
1637
1638         action->handler = handler;
1639         action->flags = IRQF_PERCPU | IRQF_NO_SUSPEND;
1640         action->name = devname;
1641         action->percpu_dev_id = dev_id;
1642
1643         chip_bus_lock(desc);
1644         retval = __setup_irq(irq, desc, action);
1645         chip_bus_sync_unlock(desc);
1646
1647         if (retval)
1648                 kfree(action);
1649
1650         return retval;
1651 }