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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         unsigned long flags;
 220         int shared = 0;
 221
 222         if (irq >= NR_IRQS)
 223                 return -EINVAL;
 224
 225         if (desc->chip == &no_irq_chip)
 226                 return -ENOSYS;
 227         /*
 228          * Some drivers like serial.c use request_irq() heavily,
 229          * so we have to be careful not to interfere with a
 230          * running system.
 231          */
 232         if (new->flags & IRQF_SAMPLE_RANDOM) {
 233                 /*
 234                  * This function might sleep, we want to call it first,
 235                  * outside of the atomic block.
 236                  * Yes, this might clear the entropy pool if the wrong
 237                  * driver is attempted to be loaded, without actually
 238                  * installing a new handler, but is this really a problem,
 239                  * only the sysadmin is able to do this.
 240                  */
 241                 rand_initialize_irq(irq);
 242         }
 243
 244         /*
 245          * The following block of code has to be executed atomically
 246          */
 247         spin_lock_irqsave(&desc->lock, flags);
 248         p = &desc->action;
 249         old = *p;
 250         if (old) {
 251                 /*
 252                  * Can't share interrupts unless both agree to and are
 253                  * the same type (level, edge, polarity). So both flag
 254                  * fields must have IRQF_SHARED set and the bits which
 255                  * set the trigger type must match.
 256                  */
 257                 if (!((old->flags & new->flags) & IRQF_SHARED) ||
 258                     ((old->flags ^ new->flags) & IRQF_TRIGGER_MASK))
 259                         goto mismatch;
 260
 261 #if defined(CONFIG_IRQ_PER_CPU)
 262                 /* All handlers must agree on per-cpuness */
 263                 if ((old->flags & IRQF_PERCPU) !=
 264                     (new->flags & IRQF_PERCPU))
 265                         goto mismatch;
 266 #endif
 267
 268                 /* add new interrupt at end of irq queue */
 269                 do {
 270                         p = &old->next;
 271                         old = *p;
 272                 } while (old);
 273                 shared = 1;
 274         }
 275
 276         *p = new;
 277 #if defined(CONFIG_IRQ_PER_CPU)
 278         if (new->flags & IRQF_PERCPU)
 279                 desc->status |= IRQ_PER_CPU;
 280 #endif
 281         if (!shared) {
 282                 irq_chip_set_defaults(desc->chip);
 283
 284                 /* Setup the type (level, edge polarity) if configured: */
 285                 if (new->flags & IRQF_TRIGGER_MASK) {
 286                         if (desc->chip && desc->chip->set_type)
 287                                 desc->chip->set_type(irq,
 288                                                 new->flags & IRQF_TRIGGER_MASK);
 289                         else
 290                                 /*
 291                                  * IRQF_TRIGGER_* but the PIC does not support
 292                                  * multiple flow-types?
 293                                  */
 294                                 printk(KERN_WARNING "No IRQF_TRIGGER set_type "
 295                                        "function for IRQ %d (%s)\n", irq,
 296                                        desc->chip ? desc->chip->name :
 297                                        "unknown");
 298                 } else
 299                         compat_irq_chip_set_default_handler(desc);
 300
 301                 desc->status &= ~(IRQ_AUTODETECT | IRQ_WAITING |
 302                                   IRQ_INPROGRESS);
 303
 304                 if (!(desc->status & IRQ_NOAUTOEN)) {
 305                         desc->depth = 0;
 306                         desc->status &= ~IRQ_DISABLED;
 307                         if (desc->chip->startup)
 308                                 desc->chip->startup(irq);
 309                         else
 310                                 desc->chip->enable(irq);
 311                 } else
 312                         /* Undo nested disables: */
 313                         desc->depth = 1;
 314         }
 315         spin_unlock_irqrestore(&desc->lock, flags);
 316
 317         new->irq = irq;
 318         register_irq_proc(irq);
 319         new->dir = NULL;
 320         register_handler_proc(irq, new);
 321
 322         return 0;
 323
 324 mismatch:
 325         spin_unlock_irqrestore(&desc->lock, flags);
 326         if (!(new->flags & IRQF_PROBE_SHARED)) {
 327                 printk(KERN_ERR "IRQ handler type mismatch for IRQ %d\n", irq);
 328                 dump_stack();
 329         }
 330         return -EBUSY;
 331 }
 332
 333 /**
 334  *      free_irq - free an interrupt
 335  *      @irq: Interrupt line to free
 336  *      @dev_id: Device identity to free
 337  *
 338  *      Remove an interrupt handler. The handler is removed and if the
 339  *      interrupt line is no longer in use by any driver it is disabled.
 340  *      On a shared IRQ the caller must ensure the interrupt is disabled
 341  *      on the card it drives before calling this function. The function
 342  *      does not return until any executing interrupts for this IRQ
 343  *      have completed.
 344  *
 345  *      This function must not be called from interrupt context.
 346  */
 347 void free_irq(unsigned int irq, void *dev_id)
 348 {
 349         struct irq_desc *desc;
 350         struct irqaction **p;
 351         unsigned long flags;
 352
 353         WARN_ON(in_interrupt());
 354         if (irq >= NR_IRQS)
 355                 return;
 356
 357         desc = irq_desc + irq;
 358         spin_lock_irqsave(&desc->lock, flags);
 359         p = &desc->action;
 360         for (;;) {
 361                 struct irqaction *action = *p;
 362
 363                 if (action) {
 364                         struct irqaction **pp = p;
 365
 366                         p = &action->next;
 367                         if (action->dev_id != dev_id)
 368                                 continue;
 369
 370                         /* Found it - now remove it from the list of entries */
 371                         *pp = action->next;
 372
 373                         /* Currently used only by UML, might disappear one day.*/
 374 #ifdef CONFIG_IRQ_RELEASE_METHOD
 375                         if (desc->chip->release)
 376                                 desc->chip->release(irq, dev_id);
 377 #endif
 378
 379                         if (!desc->action) {
 380                                 desc->status |= IRQ_DISABLED;
 381                                 if (desc->chip->shutdown)
 382                                         desc->chip->shutdown(irq);
 383                                 else
 384                                         desc->chip->disable(irq);
 385                         }
 386                         spin_unlock_irqrestore(&desc->lock, flags);
 387                         unregister_handler_proc(irq, action);
 388
 389                         /* Make sure it's not being used on another CPU */
 390                         synchronize_irq(irq);
 391                         kfree(action);
 392                         return;
 393                 }
 394                 printk(KERN_ERR "Trying to free already-free IRQ %d\n", irq);
 395                 spin_unlock_irqrestore(&desc->lock, flags);
 396                 return;
 397         }
 398 }
 399 EXPORT_SYMBOL(free_irq);
 400
 401 /**
 402  *      request_irq - allocate an interrupt line
 403  *      @irq: Interrupt line to allocate
 404  *      @handler: Function to be called when the IRQ occurs
 405  *      @irqflags: Interrupt type flags
 406  *      @devname: An ascii name for the claiming device
 407  *      @dev_id: A cookie passed back to the handler function
 408  *
 409  *      This call allocates interrupt resources and enables the
 410  *      interrupt line and IRQ handling. From the point this
 411  *      call is made your handler function may be invoked. Since
 412  *      your handler function must clear any interrupt the board
 413  *      raises, you must take care both to initialise your hardware
 414  *      and to set up the interrupt handler in the right order.
 415  *
 416  *      Dev_id must be globally unique. Normally the address of the
 417  *      device data structure is used as the cookie. Since the handler
 418  *      receives this value it makes sense to use it.
 419  *
 420  *      If your interrupt is shared you must pass a non NULL dev_id
 421  *      as this is required when freeing the interrupt.
 422  *
 423  *      Flags:
 424  *
 425  *      IRQF_SHARED             Interrupt is shared
 426  *      IRQF_DISABLED   Disable local interrupts while processing
 427  *      IRQF_SAMPLE_RANDOM      The interrupt can be used for entropy
 428  *
 429  */
 430 int request_irq(unsigned int irq,
 431                 irqreturn_t (*handler)(int, void *, struct pt_regs *),
 432                 unsigned long irqflags, const char *devname, void *dev_id)
 433 {
 434         struct irqaction *action;
 435         int retval;
 436
 437 #ifdef CONFIG_LOCKDEP
 438         /*
 439          * Lockdep wants atomic interrupt handlers:
 440          */
 441         irqflags |= SA_INTERRUPT;
 442 #endif
 443         /*
 444          * Sanity-check: shared interrupts must pass in a real dev-ID,
 445          * otherwise we'll have trouble later trying to figure out
 446          * which interrupt is which (messes up the interrupt freeing
 447          * logic etc).
 448          */
 449         if ((irqflags & IRQF_SHARED) && !dev_id)
 450                 return -EINVAL;
 451         if (irq >= NR_IRQS)
 452                 return -EINVAL;
 453         if (irq_desc[irq].status & IRQ_NOREQUEST)
 454                 return -EINVAL;
 455         if (!handler)
 456                 return -EINVAL;
 457
 458         action = kmalloc(sizeof(struct irqaction), GFP_ATOMIC);
 459         if (!action)
 460                 return -ENOMEM;
 461
 462         action->handler = handler;
 463         action->flags = irqflags;
 464         cpus_clear(action->mask);
 465         action->name = devname;
 466         action->next = NULL;
 467         action->dev_id = dev_id;
 468
 469         select_smp_affinity(irq);
 470
 471         retval = setup_irq(irq, action);
 472         if (retval)
 473                 kfree(action);
 474
 475         return retval;
 476 }
 477 EXPORT_SYMBOL(request_irq);
 478