kernel/irq/manage.c

   1 /*
   2  * linux/kernel/irq/manage.c
   3  *
   4  * Copyright (C) 1992, 1998-2004 Linus Torvalds, Ingo Molnar
   5  *
   6  * This file contains driver APIs to the irq subsystem.
   7  */
   8
   9 #include <linux/config.h>
  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 cpumask_t irq_affinity[NR_IRQS] = { [0 ... NR_IRQS-1] = CPU_MASK_ALL };
  20
  21 #if defined (CONFIG_GENERIC_PENDING_IRQ) || defined (CONFIG_IRQBALANCE)
  22 cpumask_t __cacheline_aligned pending_irq_cpumask[NR_IRQS];
  23 #endif
  24
  25 /**
  26  *      synchronize_irq - wait for pending IRQ handlers (on other CPUs)
  27  *      @irq: interrupt number to wait for
  28  *
  29  *      This function waits for any pending IRQ handlers for this interrupt
  30  *      to complete before returning. If you use this function while
  31  *      holding a resource the IRQ handler may need you will deadlock.
  32  *
  33  *      This function may be called - with care - from IRQ context.
  34  */
  35 void synchronize_irq(unsigned int irq)
  36 {
  37         struct irq_desc *desc = irq_desc + irq;
  38
  39         if (irq >= NR_IRQS)
  40                 return;
  41
  42         while (desc->status & IRQ_INPROGRESS)
  43                 cpu_relax();
  44 }
  45
  46 EXPORT_SYMBOL(synchronize_irq);
  47
  48 #endif
  49
  50 /**
  51  *      disable_irq_nosync - disable an irq without waiting
  52  *      @irq: Interrupt to disable
  53  *
  54  *      Disable the selected interrupt line.  Disables and Enables are
  55  *      nested.
  56  *      Unlike disable_irq(), this function does not ensure existing
  57  *      instances of the IRQ handler have completed before returning.
  58  *
  59  *      This function may be called from IRQ context.
  60  */
  61 void disable_irq_nosync(unsigned int irq)
  62 {
  63         irq_desc_t *desc = irq_desc + irq;
  64         unsigned long flags;
  65
  66         if (irq >= NR_IRQS)
  67                 return;
  68
  69         spin_lock_irqsave(&desc->lock, flags);
  70         if (!desc->depth++) {
  71                 desc->status |= IRQ_DISABLED;
  72                 desc->handler->disable(irq);
  73         }
  74         spin_unlock_irqrestore(&desc->lock, flags);
  75 }
  76
  77 EXPORT_SYMBOL(disable_irq_nosync);
  78
  79 /**
  80  *      disable_irq - disable an irq and wait for completion
  81  *      @irq: Interrupt to disable
  82  *
  83  *      Disable the selected interrupt line.  Enables and Disables are
  84  *      nested.
  85  *      This function waits for any pending IRQ handlers for this interrupt
  86  *      to complete before returning. If you use this function while
  87  *      holding a resource the IRQ handler may need you will deadlock.
  88  *
  89  *      This function may be called - with care - from IRQ context.
  90  */
  91 void disable_irq(unsigned int irq)
  92 {
  93         irq_desc_t *desc = irq_desc + irq;
  94
  95         if (irq >= NR_IRQS)
  96                 return;
  97
  98         disable_irq_nosync(irq);
  99         if (desc->action)
 100                 synchronize_irq(irq);
 101 }
 102
 103 EXPORT_SYMBOL(disable_irq);
 104
 105 /**
 106  *      enable_irq - enable handling of an irq
 107  *      @irq: Interrupt to enable
 108  *
 109  *      Undoes the effect of one call to disable_irq().  If this
 110  *      matches the last disable, processing of interrupts on this
 111  *      IRQ line is re-enabled.
 112  *
 113  *      This function may be called from IRQ context.
 114  */
 115 void enable_irq(unsigned int irq)
 116 {
 117         irq_desc_t *desc = irq_desc + irq;
 118         unsigned long flags;
 119
 120         if (irq >= NR_IRQS)
 121                 return;
 122
 123         spin_lock_irqsave(&desc->lock, flags);
 124         switch (desc->depth) {
 125         case 0:
 126                 WARN_ON(1);
 127                 break;
 128         case 1: {
 129                 unsigned int status = desc->status & ~IRQ_DISABLED;
 130
 131                 desc->status = status;
 132                 if ((status & (IRQ_PENDING | IRQ_REPLAY)) == IRQ_PENDING) {
 133                         desc->status = status | IRQ_REPLAY;
 134                         hw_resend_irq(desc->handler,irq);
 135                 }
 136                 desc->handler->enable(irq);
 137                 /* fall-through */
 138         }
 139         default:
 140                 desc->depth--;
 141         }
 142         spin_unlock_irqrestore(&desc->lock, flags);
 143 }
 144
 145 EXPORT_SYMBOL(enable_irq);
 146
 147 /*
 148  * Internal function that tells the architecture code whether a
 149  * particular irq has been exclusively allocated or is available
 150  * for driver use.
 151  */
 152 int can_request_irq(unsigned int irq, unsigned long irqflags)
 153 {
 154         struct irqaction *action;
 155
 156         if (irq >= NR_IRQS)
 157                 return 0;
 158
 159         action = irq_desc[irq].action;
 160         if (action)
 161                 if (irqflags & action->flags & SA_SHIRQ)
 162                         action = NULL;
 163
 164         return !action;
 165 }
 166
 167 /*
 168  * Internal function to register an irqaction - typically used to
 169  * allocate special interrupts that are part of the architecture.
 170  */
 171 int setup_irq(unsigned int irq, struct irqaction * new)
 172 {
 173         struct irq_desc *desc = irq_desc + irq;
 174         struct irqaction *old, **p;
 175         unsigned long flags;
 176         int shared = 0;
 177
 178         if (irq >= NR_IRQS)
 179                 return -EINVAL;
 180
 181         if (desc->handler == &no_irq_type)
 182                 return -ENOSYS;
 183         /*
 184          * Some drivers like serial.c use request_irq() heavily,
 185          * so we have to be careful not to interfere with a
 186          * running system.
 187          */
 188         if (new->flags & SA_SAMPLE_RANDOM) {
 189                 /*
 190                  * This function might sleep, we want to call it first,
 191                  * outside of the atomic block.
 192                  * Yes, this might clear the entropy pool if the wrong
 193                  * driver is attempted to be loaded, without actually
 194                  * installing a new handler, but is this really a problem,
 195                  * only the sysadmin is able to do this.
 196                  */
 197                 rand_initialize_irq(irq);
 198         }
 199
 200         /*
 201          * The following block of code has to be executed atomically
 202          */
 203         spin_lock_irqsave(&desc->lock,flags);
 204         p = &desc->action;
 205         if ((old = *p) != NULL) {
 206                 /* Can't share interrupts unless both agree to */
 207                 if (!(old->flags & new->flags & SA_SHIRQ))
 208                         goto mismatch;
 209
 210 #if defined(ARCH_HAS_IRQ_PER_CPU) && defined(SA_PERCPU_IRQ)
 211                 /* All handlers must agree on per-cpuness */
 212                 if ((old->flags & IRQ_PER_CPU) != (new->flags & IRQ_PER_CPU))
 213                         goto mismatch;
 214 #endif
 215
 216                 /* add new interrupt at end of irq queue */
 217                 do {
 218                         p = &old->next;
 219                         old = *p;
 220                 } while (old);
 221                 shared = 1;
 222         }
 223
 224         *p = new;
 225 #if defined(ARCH_HAS_IRQ_PER_CPU) && defined(SA_PERCPU_IRQ)
 226         if (new->flags & SA_PERCPU_IRQ)
 227                 desc->status |= IRQ_PER_CPU;
 228 #endif
 229         if (!shared) {
 230                 desc->depth = 0;
 231                 desc->status &= ~(IRQ_DISABLED | IRQ_AUTODETECT |
 232                                   IRQ_WAITING | IRQ_INPROGRESS);
 233                 if (desc->handler->startup)
 234                         desc->handler->startup(irq);
 235                 else
 236                         desc->handler->enable(irq);
 237         }
 238         spin_unlock_irqrestore(&desc->lock,flags);
 239
 240         new->irq = irq;
 241         register_irq_proc(irq);
 242         new->dir = NULL;
 243         register_handler_proc(irq, new);
 244
 245         return 0;
 246
 247 mismatch:
 248         spin_unlock_irqrestore(&desc->lock, flags);
 249         if (!(new->flags & SA_PROBEIRQ)) {
 250                 printk(KERN_ERR "%s: irq handler mismatch\n", __FUNCTION__);
 251                 dump_stack();
 252         }
 253         return -EBUSY;
 254 }
 255
 256 /**
 257  *      free_irq - free an interrupt
 258  *      @irq: Interrupt line to free
 259  *      @dev_id: Device identity to free
 260  *
 261  *      Remove an interrupt handler. The handler is removed and if the
 262  *      interrupt line is no longer in use by any driver it is disabled.
 263  *      On a shared IRQ the caller must ensure the interrupt is disabled
 264  *      on the card it drives before calling this function. The function
 265  *      does not return until any executing interrupts for this IRQ
 266  *      have completed.
 267  *
 268  *      This function must not be called from interrupt context.
 269  */
 270 void free_irq(unsigned int irq, void *dev_id)
 271 {
 272         struct irq_desc *desc;
 273         struct irqaction **p;
 274         unsigned long flags;
 275
 276         WARN_ON(in_interrupt());
 277         if (irq >= NR_IRQS)
 278                 return;
 279
 280         desc = irq_desc + irq;
 281         spin_lock_irqsave(&desc->lock,flags);
 282         p = &desc->action;
 283         for (;;) {
 284                 struct irqaction * action = *p;
 285
 286                 if (action) {
 287                         struct irqaction **pp = p;
 288
 289                         p = &action->next;
 290                         if (action->dev_id != dev_id)
 291                                 continue;
 292
 293                         /* Found it - now remove it from the list of entries */
 294                         *pp = action->next;
 295
 296                         /* Currently used only by UML, might disappear one day.*/
 297 #ifdef CONFIG_IRQ_RELEASE_METHOD
 298                         if (desc->handler->release)
 299                                 desc->handler->release(irq, dev_id);
 300 #endif
 301
 302                         if (!desc->action) {
 303                                 desc->status |= IRQ_DISABLED;
 304                                 if (desc->handler->shutdown)
 305                                         desc->handler->shutdown(irq);
 306                                 else
 307                                         desc->handler->disable(irq);
 308                         }
 309                         spin_unlock_irqrestore(&desc->lock,flags);
 310                         unregister_handler_proc(irq, action);
 311
 312                         /* Make sure it's not being used on another CPU */
 313                         synchronize_irq(irq);
 314                         kfree(action);
 315                         return;
 316                 }
 317                 printk(KERN_ERR "Trying to free free IRQ%d\n",irq);
 318                 spin_unlock_irqrestore(&desc->lock,flags);
 319                 return;
 320         }
 321 }
 322
 323 EXPORT_SYMBOL(free_irq);
 324
 325 /**
 326  *      request_irq - allocate an interrupt line
 327  *      @irq: Interrupt line to allocate
 328  *      @handler: Function to be called when the IRQ occurs
 329  *      @irqflags: Interrupt type flags
 330  *      @devname: An ascii name for the claiming device
 331  *      @dev_id: A cookie passed back to the handler function
 332  *
 333  *      This call allocates interrupt resources and enables the
 334  *      interrupt line and IRQ handling. From the point this
 335  *      call is made your handler function may be invoked. Since
 336  *      your handler function must clear any interrupt the board
 337  *      raises, you must take care both to initialise your hardware
 338  *      and to set up the interrupt handler in the right order.
 339  *
 340  *      Dev_id must be globally unique. Normally the address of the
 341  *      device data structure is used as the cookie. Since the handler
 342  *      receives this value it makes sense to use it.
 343  *
 344  *      If your interrupt is shared you must pass a non NULL dev_id
 345  *      as this is required when freeing the interrupt.
 346  *
 347  *      Flags:
 348  *
 349  *      SA_SHIRQ                Interrupt is shared
 350  *      SA_INTERRUPT            Disable local interrupts while processing
 351  *      SA_SAMPLE_RANDOM        The interrupt can be used for entropy
 352  *
 353  */
 354 int request_irq(unsigned int irq,
 355                 irqreturn_t (*handler)(int, void *, struct pt_regs *),
 356                 unsigned long irqflags, const char * devname, void *dev_id)
 357 {
 358         struct irqaction * action;
 359         int retval;
 360
 361         /*
 362          * Sanity-check: shared interrupts must pass in a real dev-ID,
 363          * otherwise we'll have trouble later trying to figure out
 364          * which interrupt is which (messes up the interrupt freeing
 365          * logic etc).
 366          */
 367         if ((irqflags & SA_SHIRQ) && !dev_id)
 368                 return -EINVAL;
 369         if (irq >= NR_IRQS)
 370                 return -EINVAL;
 371         if (!handler)
 372                 return -EINVAL;
 373
 374         action = kmalloc(sizeof(struct irqaction), GFP_ATOMIC);
 375         if (!action)
 376                 return -ENOMEM;
 377
 378         action->handler = handler;
 379         action->flags = irqflags;
 380         cpus_clear(action->mask);
 381         action->name = devname;
 382         action->next = NULL;
 383         action->dev_id = dev_id;
 384
 385         select_smp_affinity(irq);
 386
 387         retval = setup_irq(irq, action);
 388         if (retval)
 389                 kfree(action);
 390
 391         return retval;
 392 }
 393
 394 EXPORT_SYMBOL(request_irq);
 395