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 /**
  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 "Unablanced enable_irq(%d)\n", irq);
 118                 WARN_ON(1);
 119                 break;
 120         case 1: {
 121                 unsigned int status = desc->status & ~IRQ_DISABLED;
 122
 123                 desc->status = status;
 124                 if ((status & (IRQ_PENDING | IRQ_REPLAY)) == IRQ_PENDING) {
 125                         desc->status = status | IRQ_REPLAY;
 126                         if (desc->chip && desc->chip->retrigger)
 127                                 desc->chip->retrigger(irq);
 128                 }
 129                 desc->chip->enable(irq);
 130                 /* fall-through */
 131         }
 132         default:
 133                 desc->depth--;
 134         }
 135         spin_unlock_irqrestore(&desc->lock, flags);
 136 }
 137 EXPORT_SYMBOL(enable_irq);
 138
 139 /*
 140  * Internal function that tells the architecture code whether a
 141  * particular irq has been exclusively allocated or is available
 142  * for driver use.
 143  */
 144 int can_request_irq(unsigned int irq, unsigned long irqflags)
 145 {
 146         struct irqaction *action;
 147
 148         if (irq >= NR_IRQS)
 149                 return 0;
 150
 151         action = irq_desc[irq].action;
 152         if (action)
 153                 if (irqflags & action->flags & SA_SHIRQ)
 154                         action = NULL;
 155
 156         return !action;
 157 }
 158
 159 /*
 160  * Internal function to register an irqaction - typically used to
 161  * allocate special interrupts that are part of the architecture.
 162  */
 163 int setup_irq(unsigned int irq, struct irqaction *new)
 164 {
 165         struct irq_desc *desc = irq_desc + irq;
 166         struct irqaction *old, **p;
 167         unsigned long flags;
 168         int shared = 0;
 169
 170         if (irq >= NR_IRQS)
 171                 return -EINVAL;
 172
 173         if (desc->chip == &no_irq_type)
 174                 return -ENOSYS;
 175         /*
 176          * Some drivers like serial.c use request_irq() heavily,
 177          * so we have to be careful not to interfere with a
 178          * running system.
 179          */
 180         if (new->flags & SA_SAMPLE_RANDOM) {
 181                 /*
 182                  * This function might sleep, we want to call it first,
 183                  * outside of the atomic block.
 184                  * Yes, this might clear the entropy pool if the wrong
 185                  * driver is attempted to be loaded, without actually
 186                  * installing a new handler, but is this really a problem,
 187                  * only the sysadmin is able to do this.
 188                  */
 189                 rand_initialize_irq(irq);
 190         }
 191
 192         /*
 193          * The following block of code has to be executed atomically
 194          */
 195         spin_lock_irqsave(&desc->lock, flags);
 196         p = &desc->action;
 197         old = *p;
 198         if (old) {
 199                 /* Can't share interrupts unless both agree to */
 200                 if (!(old->flags & new->flags & SA_SHIRQ))
 201                         goto mismatch;
 202
 203 #if defined(CONFIG_IRQ_PER_CPU) && defined(SA_PERCPU_IRQ)
 204                 /* All handlers must agree on per-cpuness */
 205                 if ((old->flags & IRQ_PER_CPU) != (new->flags & IRQ_PER_CPU))
 206                         goto mismatch;
 207 #endif
 208
 209                 /* add new interrupt at end of irq queue */
 210                 do {
 211                         p = &old->next;
 212                         old = *p;
 213                 } while (old);
 214                 shared = 1;
 215         }
 216
 217         *p = new;
 218 #if defined(CONFIG_IRQ_PER_CPU) && defined(SA_PERCPU_IRQ)
 219         if (new->flags & SA_PERCPU_IRQ)
 220                 desc->status |= IRQ_PER_CPU;
 221 #endif
 222         if (!shared) {
 223                 desc->depth = 0;
 224                 desc->status &= ~(IRQ_DISABLED | IRQ_AUTODETECT |
 225                                   IRQ_WAITING | IRQ_INPROGRESS);
 226                 if (desc->chip->startup)
 227                         desc->chip->startup(irq);
 228                 else
 229                         desc->chip->enable(irq);
 230         }
 231         spin_unlock_irqrestore(&desc->lock, flags);
 232
 233         new->irq = irq;
 234         register_irq_proc(irq);
 235         new->dir = NULL;
 236         register_handler_proc(irq, new);
 237
 238         return 0;
 239
 240 mismatch:
 241         spin_unlock_irqrestore(&desc->lock, flags);
 242         if (!(new->flags & SA_PROBEIRQ)) {
 243                 printk(KERN_ERR "%s: irq handler mismatch\n", __FUNCTION__);
 244                 dump_stack();
 245         }
 246         return -EBUSY;
 247 }
 248
 249 /**
 250  *      free_irq - free an interrupt
 251  *      @irq: Interrupt line to free
 252  *      @dev_id: Device identity to free
 253  *
 254  *      Remove an interrupt handler. The handler is removed and if the
 255  *      interrupt line is no longer in use by any driver it is disabled.
 256  *      On a shared IRQ the caller must ensure the interrupt is disabled
 257  *      on the card it drives before calling this function. The function
 258  *      does not return until any executing interrupts for this IRQ
 259  *      have completed.
 260  *
 261  *      This function must not be called from interrupt context.
 262  */
 263 void free_irq(unsigned int irq, void *dev_id)
 264 {
 265         struct irq_desc *desc;
 266         struct irqaction **p;
 267         unsigned long flags;
 268
 269         WARN_ON(in_interrupt());
 270         if (irq >= NR_IRQS)
 271                 return;
 272
 273         desc = irq_desc + irq;
 274         spin_lock_irqsave(&desc->lock, flags);
 275         p = &desc->action;
 276         for (;;) {
 277                 struct irqaction *action = *p;
 278
 279                 if (action) {
 280                         struct irqaction **pp = p;
 281
 282                         p = &action->next;
 283                         if (action->dev_id != dev_id)
 284                                 continue;
 285
 286                         /* Found it - now remove it from the list of entries */
 287                         *pp = action->next;
 288
 289                         /* Currently used only by UML, might disappear one day.*/
 290 #ifdef CONFIG_IRQ_RELEASE_METHOD
 291                         if (desc->chip->release)
 292                                 desc->chip->release(irq, dev_id);
 293 #endif
 294
 295                         if (!desc->action) {
 296                                 desc->status |= IRQ_DISABLED;
 297                                 if (desc->chip->shutdown)
 298                                         desc->chip->shutdown(irq);
 299                                 else
 300                                         desc->chip->disable(irq);
 301                         }
 302                         spin_unlock_irqrestore(&desc->lock, flags);
 303                         unregister_handler_proc(irq, action);
 304
 305                         /* Make sure it's not being used on another CPU */
 306                         synchronize_irq(irq);
 307                         kfree(action);
 308                         return;
 309                 }
 310                 printk(KERN_ERR "Trying to free free IRQ%d\n", irq);
 311                 spin_unlock_irqrestore(&desc->lock, flags);
 312                 return;
 313         }
 314 }
 315 EXPORT_SYMBOL(free_irq);
 316
 317 /**
 318  *      request_irq - allocate an interrupt line
 319  *      @irq: Interrupt line to allocate
 320  *      @handler: Function to be called when the IRQ occurs
 321  *      @irqflags: Interrupt type flags
 322  *      @devname: An ascii name for the claiming device
 323  *      @dev_id: A cookie passed back to the handler function
 324  *
 325  *      This call allocates interrupt resources and enables the
 326  *      interrupt line and IRQ handling. From the point this
 327  *      call is made your handler function may be invoked. Since
 328  *      your handler function must clear any interrupt the board
 329  *      raises, you must take care both to initialise your hardware
 330  *      and to set up the interrupt handler in the right order.
 331  *
 332  *      Dev_id must be globally unique. Normally the address of the
 333  *      device data structure is used as the cookie. Since the handler
 334  *      receives this value it makes sense to use it.
 335  *
 336  *      If your interrupt is shared you must pass a non NULL dev_id
 337  *      as this is required when freeing the interrupt.
 338  *
 339  *      Flags:
 340  *
 341  *      SA_SHIRQ                Interrupt is shared
 342  *      SA_INTERRUPT            Disable local interrupts while processing
 343  *      SA_SAMPLE_RANDOM        The interrupt can be used for entropy
 344  *
 345  */
 346 int request_irq(unsigned int irq,
 347                 irqreturn_t (*handler)(int, void *, struct pt_regs *),
 348                 unsigned long irqflags, const char *devname, void *dev_id)
 349 {
 350         struct irqaction *action;
 351         int retval;
 352
 353         /*
 354          * Sanity-check: shared interrupts must pass in a real dev-ID,
 355          * otherwise we'll have trouble later trying to figure out
 356          * which interrupt is which (messes up the interrupt freeing
 357          * logic etc).
 358          */
 359         if ((irqflags & SA_SHIRQ) && !dev_id)
 360                 return -EINVAL;
 361         if (irq >= NR_IRQS)
 362                 return -EINVAL;
 363         if (!handler)
 364                 return -EINVAL;
 365
 366         action = kmalloc(sizeof(struct irqaction), GFP_ATOMIC);
 367         if (!action)
 368                 return -ENOMEM;
 369
 370         action->handler = handler;
 371         action->flags = irqflags;
 372         cpus_clear(action->mask);
 373         action->name = devname;
 374         action->next = NULL;
 375         action->dev_id = dev_id;
 376
 377         select_smp_affinity(irq);
 378
 379         retval = setup_irq(irq, action);
 380         if (retval)
 381                 kfree(action);
 382
 383         return retval;
 384 }
 385 EXPORT_SYMBOL(request_irq);
 386