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