kernel/irq/handle.c

   1 /*
   2  * linux/kernel/irq/handle.c
   3  *
   4  * Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
   5  * Copyright (C) 2005-2006, Thomas Gleixner, Russell King
   6  *
   7  * This file contains the core interrupt handling code.
   8  *
   9  * Detailed information is available in Documentation/DocBook/genericirq
  10  *
  11  */
  12
  13 #include <linux/irq.h>
  14 #include <linux/module.h>
  15 #include <linux/random.h>
  16 #include <linux/interrupt.h>
  17 #include <linux/kernel_stat.h>
  18
  19 #include "internals.h"
  20
  21 /**
  22  * handle_bad_irq - handle spurious and unhandled irqs
  23  * @irq:       the interrupt number
  24  * @desc:      description of the interrupt
  25  *
  26  * Handles spurious and unhandled IRQ's. It also prints a debugmessage.
  27  */
  28 void
  29 handle_bad_irq(unsigned int irq, struct irq_desc *desc)
  30 {
  31         print_irq_desc(irq, desc);
  32         kstat_this_cpu.irqs[irq]++;
  33         ack_bad_irq(irq);
  34 }
  35
  36 /*
  37  * Linux has a controller-independent interrupt architecture.
  38  * Every controller has a 'controller-template', that is used
  39  * by the main code to do the right thing. Each driver-visible
  40  * interrupt source is transparently wired to the appropriate
  41  * controller. Thus drivers need not be aware of the
  42  * interrupt-controller.
  43  *
  44  * The code is designed to be easily extended with new/different
  45  * interrupt controllers, without having to do assembly magic or
  46  * having to touch the generic code.
  47  *
  48  * Controller mappings for all interrupt sources:
  49  */
  50 int nr_irqs = NR_IRQS;
  51 struct irq_desc irq_desc[NR_IRQS] __cacheline_aligned_in_smp = {
  52         [0 ... NR_IRQS-1] = {
  53                 .status = IRQ_DISABLED,
  54                 .chip = &no_irq_chip,
  55                 .handle_irq = handle_bad_irq,
  56                 .depth = 1,
  57                 .lock = __SPIN_LOCK_UNLOCKED(irq_desc->lock),
  58 #ifdef CONFIG_SMP
  59                 .affinity = CPU_MASK_ALL
  60 #endif
  61         }
  62 };
  63
  64 /*
  65  * What should we do if we get a hw irq event on an illegal vector?
  66  * Each architecture has to answer this themself.
  67  */
  68 static void ack_bad(unsigned int irq)
  69 {
  70         print_irq_desc(irq, irq_desc + irq);
  71         ack_bad_irq(irq);
  72 }
  73
  74 /*
  75  * NOP functions
  76  */
  77 static void noop(unsigned int irq)
  78 {
  79 }
  80
  81 static unsigned int noop_ret(unsigned int irq)
  82 {
  83         return 0;
  84 }
  85
  86 /*
  87  * Generic no controller implementation
  88  */
  89 struct irq_chip no_irq_chip = {
  90         .name           = "none",
  91         .startup        = noop_ret,
  92         .shutdown       = noop,
  93         .enable         = noop,
  94         .disable        = noop,
  95         .ack            = ack_bad,
  96         .end            = noop,
  97 };
  98
  99 /*
 100  * Generic dummy implementation which can be used for
 101  * real dumb interrupt sources
 102  */
 103 struct irq_chip dummy_irq_chip = {
 104         .name           = "dummy",
 105         .startup        = noop_ret,
 106         .shutdown       = noop,
 107         .enable         = noop,
 108         .disable        = noop,
 109         .ack            = noop,
 110         .mask           = noop,
 111         .unmask         = noop,
 112         .end            = noop,
 113 };
 114
 115 /*
 116  * Special, empty irq handler:
 117  */
 118 irqreturn_t no_action(int cpl, void *dev_id)
 119 {
 120         return IRQ_NONE;
 121 }
 122
 123 /**
 124  * handle_IRQ_event - irq action chain handler
 125  * @irq:        the interrupt number
 126  * @action:     the interrupt action chain for this irq
 127  *
 128  * Handles the action chain of an irq event
 129  */
 130 irqreturn_t handle_IRQ_event(unsigned int irq, struct irqaction *action)
 131 {
 132         irqreturn_t ret, retval = IRQ_NONE;
 133         unsigned int status = 0;
 134
 135         if (!(action->flags & IRQF_DISABLED))
 136                 local_irq_enable_in_hardirq();
 137
 138         do {
 139                 ret = action->handler(irq, action->dev_id);
 140                 if (ret == IRQ_HANDLED)
 141                         status |= action->flags;
 142                 retval |= ret;
 143                 action = action->next;
 144         } while (action);
 145
 146         if (status & IRQF_SAMPLE_RANDOM)
 147                 add_interrupt_randomness(irq);
 148         local_irq_disable();
 149
 150         return retval;
 151 }
 152
 153 #ifndef CONFIG_GENERIC_HARDIRQS_NO__DO_IRQ
 154 /**
 155  * __do_IRQ - original all in one highlevel IRQ handler
 156  * @irq:        the interrupt number
 157  *
 158  * __do_IRQ handles all normal device IRQ's (the special
 159  * SMP cross-CPU interrupts have their own specific
 160  * handlers).
 161  *
 162  * This is the original x86 implementation which is used for every
 163  * interrupt type.
 164  */
 165 unsigned int __do_IRQ(unsigned int irq)
 166 {
 167         struct irq_desc *desc = irq_desc + irq;
 168         struct irqaction *action;
 169         unsigned int status;
 170
 171         kstat_this_cpu.irqs[irq]++;
 172         if (CHECK_IRQ_PER_CPU(desc->status)) {
 173                 irqreturn_t action_ret;
 174
 175                 /*
 176                  * No locking required for CPU-local interrupts:
 177                  */
 178                 if (desc->chip->ack)
 179                         desc->chip->ack(irq);
 180                 if (likely(!(desc->status & IRQ_DISABLED))) {
 181                         action_ret = handle_IRQ_event(irq, desc->action);
 182                         if (!noirqdebug)
 183                                 note_interrupt(irq, desc, action_ret);
 184                 }
 185                 desc->chip->end(irq);
 186                 return 1;
 187         }
 188
 189         spin_lock(&desc->lock);
 190         if (desc->chip->ack)
 191                 desc->chip->ack(irq);
 192         /*
 193          * REPLAY is when Linux resends an IRQ that was dropped earlier
 194          * WAITING is used by probe to mark irqs that are being tested
 195          */
 196         status = desc->status & ~(IRQ_REPLAY | IRQ_WAITING);
 197         status |= IRQ_PENDING; /* we _want_ to handle it */
 198
 199         /*
 200          * If the IRQ is disabled for whatever reason, we cannot
 201          * use the action we have.
 202          */
 203         action = NULL;
 204         if (likely(!(status & (IRQ_DISABLED | IRQ_INPROGRESS)))) {
 205                 action = desc->action;
 206                 status &= ~IRQ_PENDING; /* we commit to handling */
 207                 status |= IRQ_INPROGRESS; /* we are handling it */
 208         }
 209         desc->status = status;
 210
 211         /*
 212          * If there is no IRQ handler or it was disabled, exit early.
 213          * Since we set PENDING, if another processor is handling
 214          * a different instance of this same irq, the other processor
 215          * will take care of it.
 216          */
 217         if (unlikely(!action))
 218                 goto out;
 219
 220         /*
 221          * Edge triggered interrupts need to remember
 222          * pending events.
 223          * This applies to any hw interrupts that allow a second
 224          * instance of the same irq to arrive while we are in do_IRQ
 225          * or in the handler. But the code here only handles the _second_
 226          * instance of the irq, not the third or fourth. So it is mostly
 227          * useful for irq hardware that does not mask cleanly in an
 228          * SMP environment.
 229          */
 230         for (;;) {
 231                 irqreturn_t action_ret;
 232
 233                 spin_unlock(&desc->lock);
 234
 235                 action_ret = handle_IRQ_event(irq, action);
 236                 if (!noirqdebug)
 237                         note_interrupt(irq, desc, action_ret);
 238
 239                 spin_lock(&desc->lock);
 240                 if (likely(!(desc->status & IRQ_PENDING)))
 241                         break;
 242                 desc->status &= ~IRQ_PENDING;
 243         }
 244         desc->status &= ~IRQ_INPROGRESS;
 245
 246 out:
 247         /*
 248          * The ->end() handler has to deal with interrupts which got
 249          * disabled while the handler was running.
 250          */
 251         desc->chip->end(irq);
 252         spin_unlock(&desc->lock);
 253
 254         return 1;
 255 }
 256 #endif
 257
 258 #ifdef CONFIG_TRACE_IRQFLAGS
 259
 260 /*
 261  * lockdep: we want to handle all irq_desc locks as a single lock-class:
 262  */
 263 static struct lock_class_key irq_desc_lock_class;
 264
 265 void early_init_irq_lock_class(void)
 266 {
 267         int i;
 268
 269         for (i = 0; i < nr_irqs; i++)
 270                 lockdep_set_class(&irq_desc[i].lock, &irq_desc_lock_class);
 271 }
 272
 273 #endif