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