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   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/module.h>
  12 #include <linux/random.h>
  13 #include <linux/interrupt.h>
  14 #include <linux/slab.h>
  15
  16 #include "internals.h"
  17
  18 #ifdef CONFIG_SMP
  19
  20 cpumask_t irq_default_affinity = CPU_MASK_ALL;
  21
  22 /**
  23  *      synchronize_irq - wait for pending IRQ handlers (on other CPUs)
  24  *      @irq: interrupt number to wait for
  25  *
  26  *      This function waits for any pending IRQ handlers for this interrupt
  27  *      to complete before returning. If you use this function while
  28  *      holding a resource the IRQ handler may need you will deadlock.
  29  *
  30  *      This function may be called - with care - from IRQ context.
  31  */
  32 void synchronize_irq(unsigned int irq)
  33 {
  34         struct irq_desc *desc = irq_to_desc(irq);
  35         unsigned int status;
  36
  37         if (!desc)
  38                 return;
  39
  40         do {
  41                 unsigned long flags;
  42
  43                 /*
  44                  * Wait until we're out of the critical section.  This might
  45                  * give the wrong answer due to the lack of memory barriers.
  46                  */
  47                 while (desc->status & IRQ_INPROGRESS)
  48                         cpu_relax();
  49
  50                 /* Ok, that indicated we're done: double-check carefully. */
  51                 spin_lock_irqsave(&desc->lock, flags);
  52                 status = desc->status;
  53                 spin_unlock_irqrestore(&desc->lock, flags);
  54
  55                 /* Oops, that failed? */
  56         } while (status & IRQ_INPROGRESS);
  57 }
  58 EXPORT_SYMBOL(synchronize_irq);
  59
  60 /**
  61  *      irq_can_set_affinity - Check if the affinity of a given irq can be set
  62  *      @irq:           Interrupt to check
  63  *
  64  */
  65 int irq_can_set_affinity(unsigned int irq)
  66 {
  67         struct irq_desc *desc = irq_to_desc(irq);
  68
  69         if (CHECK_IRQ_PER_CPU(desc->status) || !desc->chip ||
  70             !desc->chip->set_affinity)
  71                 return 0;
  72
  73         return 1;
  74 }
  75
  76 /**
  77  *      irq_set_affinity - Set the irq affinity of a given irq
  78  *      @irq:           Interrupt to set affinity
  79  *      @cpumask:       cpumask
  80  *
  81  */
  82 int irq_set_affinity(unsigned int irq, cpumask_t cpumask)
  83 {
  84         struct irq_desc *desc = irq_to_desc(irq);
  85
  86         if (!desc->chip->set_affinity)
  87                 return -EINVAL;
  88
  89 #ifdef CONFIG_GENERIC_PENDING_IRQ
  90         if (desc->status & IRQ_MOVE_PCNTXT || desc->status & IRQ_DISABLED) {
  91                 unsigned long flags;
  92
  93                 spin_lock_irqsave(&desc->lock, flags);
  94                 desc->affinity = cpumask;
  95                 desc->chip->set_affinity(irq, cpumask);
  96                 spin_unlock_irqrestore(&desc->lock, flags);
  97         } else
  98                 set_pending_irq(irq, cpumask);
  99 #else
 100         desc->affinity = cpumask;
 101         desc->chip->set_affinity(irq, cpumask);
 102 #endif
 103         return 0;
 104 }
 105
 106 #ifndef CONFIG_AUTO_IRQ_AFFINITY
 107 /*
 108  * Generic version of the affinity autoselector.
 109  */
 110 int irq_select_affinity(unsigned int irq)
 111 {
 112         cpumask_t mask;
 113         struct irq_desc *desc;
 114
 115         if (!irq_can_set_affinity(irq))
 116                 return 0;
 117
 118         cpus_and(mask, cpu_online_map, irq_default_affinity);
 119
 120         desc = irq_to_desc(irq);
 121         desc->affinity = mask;
 122         desc->chip->set_affinity(irq, mask);
 123
 124         return 0;
 125 }
 126 #endif
 127
 128 #endif
 129
 130 /**
 131  *      disable_irq_nosync - disable an irq without waiting
 132  *      @irq: Interrupt to disable
 133  *
 134  *      Disable the selected interrupt line.  Disables and Enables are
 135  *      nested.
 136  *      Unlike disable_irq(), this function does not ensure existing
 137  *      instances of the IRQ handler have completed before returning.
 138  *
 139  *      This function may be called from IRQ context.
 140  */
 141 void disable_irq_nosync(unsigned int irq)
 142 {
 143         struct irq_desc *desc = irq_to_desc(irq);
 144         unsigned long flags;
 145
 146         if (!desc)
 147                 return;
 148
 149         spin_lock_irqsave(&desc->lock, flags);
 150         if (!desc->depth++) {
 151                 desc->status |= IRQ_DISABLED;
 152                 desc->chip->disable(irq);
 153         }
 154         spin_unlock_irqrestore(&desc->lock, flags);
 155 }
 156 EXPORT_SYMBOL(disable_irq_nosync);
 157
 158 /**
 159  *      disable_irq - disable an irq and wait for completion
 160  *      @irq: Interrupt to disable
 161  *
 162  *      Disable the selected interrupt line.  Enables and Disables are
 163  *      nested.
 164  *      This function waits for any pending IRQ handlers for this interrupt
 165  *      to complete before returning. If you use this function while
 166  *      holding a resource the IRQ handler may need you will deadlock.
 167  *
 168  *      This function may be called - with care - from IRQ context.
 169  */
 170 void disable_irq(unsigned int irq)
 171 {
 172         struct irq_desc *desc = irq_to_desc(irq);
 173
 174         if (!desc)
 175                 return;
 176
 177         disable_irq_nosync(irq);
 178         if (desc->action)
 179                 synchronize_irq(irq);
 180 }
 181 EXPORT_SYMBOL(disable_irq);
 182
 183 static void __enable_irq(struct irq_desc *desc, unsigned int irq)
 184 {
 185         switch (desc->depth) {
 186         case 0:
 187                 WARN(1, KERN_WARNING "Unbalanced enable for IRQ %d\n", irq);
 188                 break;
 189         case 1: {
 190                 unsigned int status = desc->status & ~IRQ_DISABLED;
 191
 192                 /* Prevent probing on this irq: */
 193                 desc->status = status | IRQ_NOPROBE;
 194                 check_irq_resend(desc, irq);
 195                 /* fall-through */
 196         }
 197         default:
 198                 desc->depth--;
 199         }
 200 }
 201
 202 /**
 203  *      enable_irq - enable handling of an irq
 204  *      @irq: Interrupt to enable
 205  *
 206  *      Undoes the effect of one call to disable_irq().  If this
 207  *      matches the last disable, processing of interrupts on this
 208  *      IRQ line is re-enabled.
 209  *
 210  *      This function may be called from IRQ context.
 211  */
 212 void enable_irq(unsigned int irq)
 213 {
 214         struct irq_desc *desc = irq_to_desc(irq);
 215         unsigned long flags;
 216
 217         if (!desc)
 218                 return;
 219
 220         spin_lock_irqsave(&desc->lock, flags);
 221         __enable_irq(desc, irq);
 222         spin_unlock_irqrestore(&desc->lock, flags);
 223 }
 224 EXPORT_SYMBOL(enable_irq);
 225
 226 static int set_irq_wake_real(unsigned int irq, unsigned int on)
 227 {
 228         struct irq_desc *desc = irq_to_desc(irq);
 229         int ret = -ENXIO;
 230
 231         if (desc->chip->set_wake)
 232                 ret = desc->chip->set_wake(irq, on);
 233
 234         return ret;
 235 }
 236
 237 /**
 238  *      set_irq_wake - control irq power management wakeup
 239  *      @irq:   interrupt to control
 240  *      @on:    enable/disable power management wakeup
 241  *
 242  *      Enable/disable power management wakeup mode, which is
 243  *      disabled by default.  Enables and disables must match,
 244  *      just as they match for non-wakeup mode support.
 245  *
 246  *      Wakeup mode lets this IRQ wake the system from sleep
 247  *      states like "suspend to RAM".
 248  */
 249 int set_irq_wake(unsigned int irq, unsigned int on)
 250 {
 251         struct irq_desc *desc = irq_to_desc(irq);
 252         unsigned long flags;
 253         int ret = 0;
 254
 255         /* wakeup-capable irqs can be shared between drivers that
 256          * don't need to have the same sleep mode behaviors.
 257          */
 258         spin_lock_irqsave(&desc->lock, flags);
 259         if (on) {
 260                 if (desc->wake_depth++ == 0) {
 261                         ret = set_irq_wake_real(irq, on);
 262                         if (ret)
 263                                 desc->wake_depth = 0;
 264                         else
 265                                 desc->status |= IRQ_WAKEUP;
 266                 }
 267         } else {
 268                 if (desc->wake_depth == 0) {
 269                         WARN(1, "Unbalanced IRQ %d wake disable\n", irq);
 270                 } else if (--desc->wake_depth == 0) {
 271                         ret = set_irq_wake_real(irq, on);
 272                         if (ret)
 273                                 desc->wake_depth = 1;
 274                         else
 275                                 desc->status &= ~IRQ_WAKEUP;
 276                 }
 277         }
 278
 279         spin_unlock_irqrestore(&desc->lock, flags);
 280         return ret;
 281 }
 282 EXPORT_SYMBOL(set_irq_wake);
 283
 284 /*
 285  * Internal function that tells the architecture code whether a
 286  * particular irq has been exclusively allocated or is available
 287  * for driver use.
 288  */
 289 int can_request_irq(unsigned int irq, unsigned long irqflags)
 290 {
 291         struct irq_desc *desc = irq_to_desc(irq);
 292         struct irqaction *action;
 293
 294         if (!desc)
 295                 return 0;
 296
 297         if (desc->status & IRQ_NOREQUEST)
 298                 return 0;
 299
 300         action = desc->action;
 301         if (action)
 302                 if (irqflags & action->flags & IRQF_SHARED)
 303                         action = NULL;
 304
 305         return !action;
 306 }
 307
 308 void compat_irq_chip_set_default_handler(struct irq_desc *desc)
 309 {
 310         /*
 311          * If the architecture still has not overriden
 312          * the flow handler then zap the default. This
 313          * should catch incorrect flow-type setting.
 314          */
 315         if (desc->handle_irq == &handle_bad_irq)
 316                 desc->handle_irq = NULL;
 317 }
 318
 319 int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
 320                 unsigned long flags)
 321 {
 322         int ret;
 323         struct irq_chip *chip = desc->chip;
 324
 325         if (!chip || !chip->set_type) {
 326                 /*
 327                  * IRQF_TRIGGER_* but the PIC does not support multiple
 328                  * flow-types?
 329                  */
 330                 pr_warning("No set_type function for IRQ %d (%s)\n", irq,
 331                                 chip ? (chip->name ? : "unknown") : "unknown");
 332                 return 0;
 333         }
 334
 335         ret = chip->set_type(irq, flags & IRQF_TRIGGER_MASK);
 336
 337         if (ret)
 338                 pr_err("setting trigger mode %d for irq %u failed (%pF)\n",
 339                                 (int)(flags & IRQF_TRIGGER_MASK),
 340                                 irq, chip->set_type);
 341         else {
 342                 /* note that IRQF_TRIGGER_MASK == IRQ_TYPE_SENSE_MASK */
 343                 desc->status &= ~IRQ_TYPE_SENSE_MASK;
 344                 desc->status |= flags & IRQ_TYPE_SENSE_MASK;
 345         }
 346
 347         return ret;
 348 }
 349
 350 /*
 351  * Internal function to register an irqaction - typically used to
 352  * allocate special interrupts that are part of the architecture.
 353  */
 354 static int
 355 __setup_irq(unsigned int irq, struct irq_desc * desc, struct irqaction *new)
 356 {
 357         struct irqaction *old, **p;
 358         const char *old_name = NULL;
 359         unsigned long flags;
 360         int shared = 0;
 361         int ret;
 362
 363         if (!desc)
 364                 return -EINVAL;
 365
 366         if (desc->chip == &no_irq_chip)
 367                 return -ENOSYS;
 368         /*
 369          * Some drivers like serial.c use request_irq() heavily,
 370          * so we have to be careful not to interfere with a
 371          * running system.
 372          */
 373         if (new->flags & IRQF_SAMPLE_RANDOM) {
 374                 /*
 375                  * This function might sleep, we want to call it first,
 376                  * outside of the atomic block.
 377                  * Yes, this might clear the entropy pool if the wrong
 378                  * driver is attempted to be loaded, without actually
 379                  * installing a new handler, but is this really a problem,
 380                  * only the sysadmin is able to do this.
 381                  */
 382                 rand_initialize_irq(irq);
 383         }
 384
 385         /*
 386          * The following block of code has to be executed atomically
 387          */
 388         spin_lock_irqsave(&desc->lock, flags);
 389         p = &desc->action;
 390         old = *p;
 391         if (old) {
 392                 /*
 393                  * Can't share interrupts unless both agree to and are
 394                  * the same type (level, edge, polarity). So both flag
 395                  * fields must have IRQF_SHARED set and the bits which
 396                  * set the trigger type must match.
 397                  */
 398                 if (!((old->flags & new->flags) & IRQF_SHARED) ||
 399                     ((old->flags ^ new->flags) & IRQF_TRIGGER_MASK)) {
 400                         old_name = old->name;
 401                         goto mismatch;
 402                 }
 403
 404 #if defined(CONFIG_IRQ_PER_CPU)
 405                 /* All handlers must agree on per-cpuness */
 406                 if ((old->flags & IRQF_PERCPU) !=
 407                     (new->flags & IRQF_PERCPU))
 408                         goto mismatch;
 409 #endif
 410
 411                 /* add new interrupt at end of irq queue */
 412                 do {
 413                         p = &old->next;
 414                         old = *p;
 415                 } while (old);
 416                 shared = 1;
 417         }
 418
 419         if (!shared) {
 420                 irq_chip_set_defaults(desc->chip);
 421
 422                 /* Setup the type (level, edge polarity) if configured: */
 423                 if (new->flags & IRQF_TRIGGER_MASK) {
 424                         ret = __irq_set_trigger(desc, irq, new->flags);
 425
 426                         if (ret) {
 427                                 spin_unlock_irqrestore(&desc->lock, flags);
 428                                 return ret;
 429                         }
 430                 } else
 431                         compat_irq_chip_set_default_handler(desc);
 432 #if defined(CONFIG_IRQ_PER_CPU)
 433                 if (new->flags & IRQF_PERCPU)
 434                         desc->status |= IRQ_PER_CPU;
 435 #endif
 436
 437                 desc->status &= ~(IRQ_AUTODETECT | IRQ_WAITING |
 438                                   IRQ_INPROGRESS | IRQ_SPURIOUS_DISABLED);
 439
 440                 if (!(desc->status & IRQ_NOAUTOEN)) {
 441                         desc->depth = 0;
 442                         desc->status &= ~IRQ_DISABLED;
 443                         desc->chip->startup(irq);
 444                 } else
 445                         /* Undo nested disables: */
 446                         desc->depth = 1;
 447
 448                 /* Set default affinity mask once everything is setup */
 449                 irq_select_affinity(irq);
 450
 451         } else if ((new->flags & IRQF_TRIGGER_MASK)
 452                         && (new->flags & IRQF_TRIGGER_MASK)
 453                                 != (desc->status & IRQ_TYPE_SENSE_MASK)) {
 454                 /* hope the handler works with the actual trigger mode... */
 455                 pr_warning("IRQ %d uses trigger mode %d; requested %d\n",
 456                                 irq, (int)(desc->status & IRQ_TYPE_SENSE_MASK),
 457                                 (int)(new->flags & IRQF_TRIGGER_MASK));
 458         }
 459
 460         *p = new;
 461
 462         /* Exclude IRQ from balancing */
 463         if (new->flags & IRQF_NOBALANCING)
 464                 desc->status |= IRQ_NO_BALANCING;
 465
 466         /* Reset broken irq detection when installing new handler */
 467         desc->irq_count = 0;
 468         desc->irqs_unhandled = 0;
 469
 470         /*
 471          * Check whether we disabled the irq via the spurious handler
 472          * before. Reenable it and give it another chance.
 473          */
 474         if (shared && (desc->status & IRQ_SPURIOUS_DISABLED)) {
 475                 desc->status &= ~IRQ_SPURIOUS_DISABLED;
 476                 __enable_irq(desc, irq);
 477         }
 478
 479         spin_unlock_irqrestore(&desc->lock, flags);
 480
 481         new->irq = irq;
 482         register_irq_proc(irq, desc);
 483         new->dir = NULL;
 484         register_handler_proc(irq, new);
 485
 486         return 0;
 487
 488 mismatch:
 489 #ifdef CONFIG_DEBUG_SHIRQ
 490         if (!(new->flags & IRQF_PROBE_SHARED)) {
 491                 printk(KERN_ERR "IRQ handler type mismatch for IRQ %d\n", irq);
 492                 if (old_name)
 493                         printk(KERN_ERR "current handler: %s\n", old_name);
 494                 dump_stack();
 495         }
 496 #endif
 497         spin_unlock_irqrestore(&desc->lock, flags);
 498         return -EBUSY;
 499 }
 500
 501 /**
 502  *      setup_irq - setup an interrupt
 503  *      @irq: Interrupt line to setup
 504  *      @act: irqaction for the interrupt
 505  *
 506  * Used to statically setup interrupts in the early boot process.
 507  */
 508 int setup_irq(unsigned int irq, struct irqaction *act)
 509 {
 510         struct irq_desc *desc = irq_to_desc(irq);
 511
 512         return __setup_irq(irq, desc, act);
 513 }
 514
 515 /**
 516  *      free_irq - free an interrupt
 517  *      @irq: Interrupt line to free
 518  *      @dev_id: Device identity to free
 519  *
 520  *      Remove an interrupt handler. The handler is removed and if the
 521  *      interrupt line is no longer in use by any driver it is disabled.
 522  *      On a shared IRQ the caller must ensure the interrupt is disabled
 523  *      on the card it drives before calling this function. The function
 524  *      does not return until any executing interrupts for this IRQ
 525  *      have completed.
 526  *
 527  *      This function must not be called from interrupt context.
 528  */
 529 void free_irq(unsigned int irq, void *dev_id)
 530 {
 531         struct irq_desc *desc = irq_to_desc(irq);
 532         struct irqaction **p;
 533         unsigned long flags;
 534
 535         WARN_ON(in_interrupt());
 536
 537         if (!desc)
 538                 return;
 539
 540         spin_lock_irqsave(&desc->lock, flags);
 541         p = &desc->action;
 542         for (;;) {
 543                 struct irqaction *action = *p;
 544
 545                 if (action) {
 546                         struct irqaction **pp = p;
 547
 548                         p = &action->next;
 549                         if (action->dev_id != dev_id)
 550                                 continue;
 551
 552                         /* Found it - now remove it from the list of entries */
 553                         *pp = action->next;
 554
 555                         /* Currently used only by UML, might disappear one day.*/
 556 #ifdef CONFIG_IRQ_RELEASE_METHOD
 557                         if (desc->chip->release)
 558                                 desc->chip->release(irq, dev_id);
 559 #endif
 560
 561                         if (!desc->action) {
 562                                 desc->status |= IRQ_DISABLED;
 563                                 if (desc->chip->shutdown)
 564                                         desc->chip->shutdown(irq);
 565                                 else
 566                                         desc->chip->disable(irq);
 567                         }
 568                         spin_unlock_irqrestore(&desc->lock, flags);
 569                         unregister_handler_proc(irq, action);
 570
 571                         /* Make sure it's not being used on another CPU */
 572                         synchronize_irq(irq);
 573 #ifdef CONFIG_DEBUG_SHIRQ
 574                         /*
 575                          * It's a shared IRQ -- the driver ought to be
 576                          * prepared for it to happen even now it's
 577                          * being freed, so let's make sure....  We do
 578                          * this after actually deregistering it, to
 579                          * make sure that a 'real' IRQ doesn't run in
 580                          * parallel with our fake
 581                          */
 582                         if (action->flags & IRQF_SHARED) {
 583                                 local_irq_save(flags);
 584                                 action->handler(irq, dev_id);
 585                                 local_irq_restore(flags);
 586                         }
 587 #endif
 588                         kfree(action);
 589                         return;
 590                 }
 591                 printk(KERN_ERR "Trying to free already-free IRQ %d\n", irq);
 592 #ifdef CONFIG_DEBUG_SHIRQ
 593                 dump_stack();
 594 #endif
 595                 spin_unlock_irqrestore(&desc->lock, flags);
 596                 return;
 597         }
 598 }
 599 EXPORT_SYMBOL(free_irq);
 600
 601 /**
 602  *      request_irq - allocate an interrupt line
 603  *      @irq: Interrupt line to allocate
 604  *      @handler: Function to be called when the IRQ occurs
 605  *      @irqflags: Interrupt type flags
 606  *      @devname: An ascii name for the claiming device
 607  *      @dev_id: A cookie passed back to the handler function
 608  *
 609  *      This call allocates interrupt resources and enables the
 610  *      interrupt line and IRQ handling. From the point this
 611  *      call is made your handler function may be invoked. Since
 612  *      your handler function must clear any interrupt the board
 613  *      raises, you must take care both to initialise your hardware
 614  *      and to set up the interrupt handler in the right order.
 615  *
 616  *      Dev_id must be globally unique. Normally the address of the
 617  *      device data structure is used as the cookie. Since the handler
 618  *      receives this value it makes sense to use it.
 619  *
 620  *      If your interrupt is shared you must pass a non NULL dev_id
 621  *      as this is required when freeing the interrupt.
 622  *
 623  *      Flags:
 624  *
 625  *      IRQF_SHARED             Interrupt is shared
 626  *      IRQF_DISABLED   Disable local interrupts while processing
 627  *      IRQF_SAMPLE_RANDOM      The interrupt can be used for entropy
 628  *      IRQF_TRIGGER_*          Specify active edge(s) or level
 629  *
 630  */
 631 int request_irq(unsigned int irq, irq_handler_t handler,
 632                 unsigned long irqflags, const char *devname, void *dev_id)
 633 {
 634         struct irqaction *action;
 635         struct irq_desc *desc;
 636         int retval;
 637
 638 #ifdef CONFIG_LOCKDEP
 639         /*
 640          * Lockdep wants atomic interrupt handlers:
 641          */
 642         irqflags |= IRQF_DISABLED;
 643 #endif
 644         /*
 645          * Sanity-check: shared interrupts must pass in a real dev-ID,
 646          * otherwise we'll have trouble later trying to figure out
 647          * which interrupt is which (messes up the interrupt freeing
 648          * logic etc).
 649          */
 650         if ((irqflags & IRQF_SHARED) && !dev_id)
 651                 return -EINVAL;
 652
 653         desc = irq_to_desc(irq);
 654         if (!desc)
 655                 return -EINVAL;
 656
 657         if (desc->status & IRQ_NOREQUEST)
 658                 return -EINVAL;
 659         if (!handler)
 660                 return -EINVAL;
 661
 662         action = kmalloc(sizeof(struct irqaction), GFP_ATOMIC);
 663         if (!action)
 664                 return -ENOMEM;
 665
 666         action->handler = handler;
 667         action->flags = irqflags;
 668         cpus_clear(action->mask);
 669         action->name = devname;
 670         action->next = NULL;
 671         action->dev_id = dev_id;
 672
 673         retval = __setup_irq(irq, desc, action);
 674         if (retval)
 675                 kfree(action);
 676
 677 #ifdef CONFIG_DEBUG_SHIRQ
 678         if (irqflags & IRQF_SHARED) {
 679                 /*
 680                  * It's a shared IRQ -- the driver ought to be prepared for it
 681                  * to happen immediately, so let's make sure....
 682                  * We disable the irq to make sure that a 'real' IRQ doesn't
 683                  * run in parallel with our fake.
 684                  */
 685                 unsigned long flags;
 686
 687                 disable_irq(irq);
 688                 local_irq_save(flags);
 689
 690                 handler(irq, dev_id);
 691
 692                 local_irq_restore(flags);
 693                 enable_irq(irq);
 694         }
 695 #endif
 696         return retval;
 697 }
 698 EXPORT_SYMBOL(request_irq);