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