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