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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
 141  */
 142 int set_irq_wake(unsigned int irq, unsigned int on)
 143 {
 144         struct irq_desc *desc = irq_desc + irq;
 145         unsigned long flags;
 146         int ret = -ENXIO;
 147
 148         spin_lock_irqsave(&desc->lock, flags);
 149         if (desc->chip->set_wake)
 150                 ret = desc->chip->set_wake(irq, on);
 151         spin_unlock_irqrestore(&desc->lock, flags);
 152         return ret;
 153 }
 154 EXPORT_SYMBOL(set_irq_wake);
 155
 156 /*
 157  * Internal function that tells the architecture code whether a
 158  * particular irq has been exclusively allocated or is available
 159  * for driver use.
 160  */
 161 int can_request_irq(unsigned int irq, unsigned long irqflags)
 162 {
 163         struct irqaction *action;
 164
 165         if (irq >= NR_IRQS || irq_desc[irq].status & IRQ_NOREQUEST)
 166                 return 0;
 167
 168         action = irq_desc[irq].action;
 169         if (action)
 170                 if (irqflags & action->flags & IRQF_SHARED)
 171                         action = NULL;
 172
 173         return !action;
 174 }
 175
 176 void compat_irq_chip_set_default_handler(struct irq_desc *desc)
 177 {
 178         /*
 179          * If the architecture still has not overriden
 180          * the flow handler then zap the default. This
 181          * should catch incorrect flow-type setting.
 182          */
 183         if (desc->handle_irq == &handle_bad_irq)
 184                 desc->handle_irq = NULL;
 185 }
 186
 187 /*
 188  * Internal function to register an irqaction - typically used to
 189  * allocate special interrupts that are part of the architecture.
 190  */
 191 int setup_irq(unsigned int irq, struct irqaction *new)
 192 {
 193         struct irq_desc *desc = irq_desc + irq;
 194         struct irqaction *old, **p;
 195         unsigned long flags;
 196         int shared = 0;
 197
 198         if (irq >= NR_IRQS)
 199                 return -EINVAL;
 200
 201         if (desc->chip == &no_irq_chip)
 202                 return -ENOSYS;
 203         /*
 204          * Some drivers like serial.c use request_irq() heavily,
 205          * so we have to be careful not to interfere with a
 206          * running system.
 207          */
 208         if (new->flags & IRQF_SAMPLE_RANDOM) {
 209                 /*
 210                  * This function might sleep, we want to call it first,
 211                  * outside of the atomic block.
 212                  * Yes, this might clear the entropy pool if the wrong
 213                  * driver is attempted to be loaded, without actually
 214                  * installing a new handler, but is this really a problem,
 215                  * only the sysadmin is able to do this.
 216                  */
 217                 rand_initialize_irq(irq);
 218         }
 219
 220         /*
 221          * The following block of code has to be executed atomically
 222          */
 223         spin_lock_irqsave(&desc->lock, flags);
 224         p = &desc->action;
 225         old = *p;
 226         if (old) {
 227                 /*
 228                  * Can't share interrupts unless both agree to and are
 229                  * the same type (level, edge, polarity). So both flag
 230                  * fields must have IRQF_SHARED set and the bits which
 231                  * set the trigger type must match.
 232                  */
 233                 if (!((old->flags & new->flags) & IRQF_SHARED) ||
 234                     ((old->flags ^ new->flags) & IRQF_TRIGGER_MASK))
 235                         goto mismatch;
 236
 237 #if defined(CONFIG_IRQ_PER_CPU)
 238                 /* All handlers must agree on per-cpuness */
 239                 if ((old->flags & IRQF_PERCPU) !=
 240                     (new->flags & IRQF_PERCPU))
 241                         goto mismatch;
 242 #endif
 243
 244                 /* add new interrupt at end of irq queue */
 245                 do {
 246                         p = &old->next;
 247                         old = *p;
 248                 } while (old);
 249                 shared = 1;
 250         }
 251
 252         *p = new;
 253 #if defined(CONFIG_IRQ_PER_CPU)
 254         if (new->flags & IRQF_PERCPU)
 255                 desc->status |= IRQ_PER_CPU;
 256 #endif
 257         if (!shared) {
 258                 irq_chip_set_defaults(desc->chip);
 259
 260                 /* Setup the type (level, edge polarity) if configured: */
 261                 if (new->flags & IRQF_TRIGGER_MASK) {
 262                         if (desc->chip && desc->chip->set_type)
 263                                 desc->chip->set_type(irq,
 264                                                 new->flags & IRQF_TRIGGER_MASK);
 265                         else
 266                                 /*
 267                                  * IRQF_TRIGGER_* but the PIC does not support
 268                                  * multiple flow-types?
 269                                  */
 270                                 printk(KERN_WARNING "No IRQF_TRIGGER set_type "
 271                                        "function for IRQ %d (%s)\n", irq,
 272                                        desc->chip ? desc->chip->name :
 273                                        "unknown");
 274                 } else
 275                         compat_irq_chip_set_default_handler(desc);
 276
 277                 desc->status &= ~(IRQ_AUTODETECT | IRQ_WAITING |
 278                                   IRQ_INPROGRESS);
 279
 280                 if (!(desc->status & IRQ_NOAUTOEN)) {
 281                         desc->depth = 0;
 282                         desc->status &= ~IRQ_DISABLED;
 283                         if (desc->chip->startup)
 284                                 desc->chip->startup(irq);
 285                         else
 286                                 desc->chip->enable(irq);
 287                 } else
 288                         /* Undo nested disables: */
 289                         desc->depth = 1;
 290         }
 291         spin_unlock_irqrestore(&desc->lock, flags);
 292
 293         new->irq = irq;
 294         register_irq_proc(irq);
 295         new->dir = NULL;
 296         register_handler_proc(irq, new);
 297
 298         return 0;
 299
 300 mismatch:
 301         spin_unlock_irqrestore(&desc->lock, flags);
 302         if (!(new->flags & IRQF_PROBE_SHARED)) {
 303                 printk(KERN_ERR "IRQ handler type mismatch for IRQ %d\n", irq);
 304                 dump_stack();
 305         }
 306         return -EBUSY;
 307 }
 308
 309 /**
 310  *      free_irq - free an interrupt
 311  *      @irq: Interrupt line to free
 312  *      @dev_id: Device identity to free
 313  *
 314  *      Remove an interrupt handler. The handler is removed and if the
 315  *      interrupt line is no longer in use by any driver it is disabled.
 316  *      On a shared IRQ the caller must ensure the interrupt is disabled
 317  *      on the card it drives before calling this function. The function
 318  *      does not return until any executing interrupts for this IRQ
 319  *      have completed.
 320  *
 321  *      This function must not be called from interrupt context.
 322  */
 323 void free_irq(unsigned int irq, void *dev_id)
 324 {
 325         struct irq_desc *desc;
 326         struct irqaction **p;
 327         unsigned long flags;
 328
 329         WARN_ON(in_interrupt());
 330         if (irq >= NR_IRQS)
 331                 return;
 332
 333         desc = irq_desc + irq;
 334         spin_lock_irqsave(&desc->lock, flags);
 335         p = &desc->action;
 336         for (;;) {
 337                 struct irqaction *action = *p;
 338
 339                 if (action) {
 340                         struct irqaction **pp = p;
 341
 342                         p = &action->next;
 343                         if (action->dev_id != dev_id)
 344                                 continue;
 345
 346                         /* Found it - now remove it from the list of entries */
 347                         *pp = action->next;
 348
 349                         /* Currently used only by UML, might disappear one day.*/
 350 #ifdef CONFIG_IRQ_RELEASE_METHOD
 351                         if (desc->chip->release)
 352                                 desc->chip->release(irq, dev_id);
 353 #endif
 354
 355                         if (!desc->action) {
 356                                 desc->status |= IRQ_DISABLED;
 357                                 if (desc->chip->shutdown)
 358                                         desc->chip->shutdown(irq);
 359                                 else
 360                                         desc->chip->disable(irq);
 361                         }
 362                         spin_unlock_irqrestore(&desc->lock, flags);
 363                         unregister_handler_proc(irq, action);
 364
 365                         /* Make sure it's not being used on another CPU */
 366                         synchronize_irq(irq);
 367                         kfree(action);
 368                         return;
 369                 }
 370                 printk(KERN_ERR "Trying to free already-free IRQ %d\n", irq);
 371                 spin_unlock_irqrestore(&desc->lock, flags);
 372                 return;
 373         }
 374 }
 375 EXPORT_SYMBOL(free_irq);
 376
 377 /**
 378  *      request_irq - allocate an interrupt line
 379  *      @irq: Interrupt line to allocate
 380  *      @handler: Function to be called when the IRQ occurs
 381  *      @irqflags: Interrupt type flags
 382  *      @devname: An ascii name for the claiming device
 383  *      @dev_id: A cookie passed back to the handler function
 384  *
 385  *      This call allocates interrupt resources and enables the
 386  *      interrupt line and IRQ handling. From the point this
 387  *      call is made your handler function may be invoked. Since
 388  *      your handler function must clear any interrupt the board
 389  *      raises, you must take care both to initialise your hardware
 390  *      and to set up the interrupt handler in the right order.
 391  *
 392  *      Dev_id must be globally unique. Normally the address of the
 393  *      device data structure is used as the cookie. Since the handler
 394  *      receives this value it makes sense to use it.
 395  *
 396  *      If your interrupt is shared you must pass a non NULL dev_id
 397  *      as this is required when freeing the interrupt.
 398  *
 399  *      Flags:
 400  *
 401  *      IRQF_SHARED             Interrupt is shared
 402  *      IRQF_DISABLED   Disable local interrupts while processing
 403  *      IRQF_SAMPLE_RANDOM      The interrupt can be used for entropy
 404  *
 405  */
 406 int request_irq(unsigned int irq,
 407                 irqreturn_t (*handler)(int, void *, struct pt_regs *),
 408                 unsigned long irqflags, const char *devname, void *dev_id)
 409 {
 410         struct irqaction *action;
 411         int retval;
 412
 413 #ifdef CONFIG_LOCKDEP
 414         /*
 415          * Lockdep wants atomic interrupt handlers:
 416          */
 417         irqflags |= SA_INTERRUPT;
 418 #endif
 419         /*
 420          * Sanity-check: shared interrupts must pass in a real dev-ID,
 421          * otherwise we'll have trouble later trying to figure out
 422          * which interrupt is which (messes up the interrupt freeing
 423          * logic etc).
 424          */
 425         if ((irqflags & IRQF_SHARED) && !dev_id)
 426                 return -EINVAL;
 427         if (irq >= NR_IRQS)
 428                 return -EINVAL;
 429         if (irq_desc[irq].status & IRQ_NOREQUEST)
 430                 return -EINVAL;
 431         if (!handler)
 432                 return -EINVAL;
 433
 434         action = kmalloc(sizeof(struct irqaction), GFP_ATOMIC);
 435         if (!action)
 436                 return -ENOMEM;
 437
 438         action->handler = handler;
 439         action->flags = irqflags;
 440         cpus_clear(action->mask);
 441         action->name = devname;
 442         action->next = NULL;
 443         action->dev_id = dev_id;
 444
 445         select_smp_affinity(irq);
 446
 447         retval = setup_irq(irq, action);
 448         if (retval)
 449                 kfree(action);
 450
 451         return retval;
 452 }
 453 EXPORT_SYMBOL(request_irq);
 454