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 handle_bad_irq(unsigned int irq, struct irq_desc *desc)
  29 {
  30         print_irq_desc(irq, desc);
  31         kstat_incr_irqs_this_cpu(irq, desc);
  32         ack_bad_irq(irq);
  33 }
  34
  35 /*
  36  * Linux has a controller-independent interrupt architecture.
  37  * Every controller has a 'controller-template', that is used
  38  * by the main code to do the right thing. Each driver-visible
  39  * interrupt source is transparently wired to the appropriate
  40  * controller. Thus drivers need not be aware of the
  41  * interrupt-controller.
  42  *
  43  * The code is designed to be easily extended with new/different
  44  * interrupt controllers, without having to do assembly magic or
  45  * having to touch the generic code.
  46  *
  47  * Controller mappings for all interrupt sources:
  48  */
  49 int nr_irqs = NR_IRQS;
  50 EXPORT_SYMBOL_GPL(nr_irqs);
  51
  52 struct irq_desc irq_desc[NR_IRQS] __cacheline_aligned_in_smp = {
  53         [0 ... NR_IRQS-1] = {
  54                 .status = IRQ_DISABLED,
  55                 .chip = &no_irq_chip,
  56                 .handle_irq = handle_bad_irq,
  57                 .depth = 1,
  58                 .lock = __SPIN_LOCK_UNLOCKED(irq_desc->lock),
  59 #ifdef CONFIG_SMP
  60                 .affinity = CPU_MASK_ALL
  61 #endif
  62         }
  63 };
  64
  65 /*
  66  * What should we do if we get a hw irq event on an illegal vector?
  67  * Each architecture has to answer this themself.
  68  */
  69 static void ack_bad(unsigned int irq)
  70 {
  71         struct irq_desc *desc;
  72
  73         desc = irq_to_desc(irq);
  74         print_irq_desc(irq, desc);
  75         ack_bad_irq(irq);
  76 }
  77
  78 /*
  79  * NOP functions
  80  */
  81 static void noop(unsigned int irq)
  82 {
  83 }
  84
  85 static unsigned int noop_ret(unsigned int irq)
  86 {
  87         return 0;
  88 }
  89
  90 /*
  91  * Generic no controller implementation
  92  */
  93 struct irq_chip no_irq_chip = {
  94         .name           = "none",
  95         .startup        = noop_ret,
  96         .shutdown       = noop,
  97         .enable         = noop,
  98         .disable        = noop,
  99         .ack            = ack_bad,
 100         .end            = noop,
 101 };
 102
 103 /*
 104  * Generic dummy implementation which can be used for
 105  * real dumb interrupt sources
 106  */
 107 struct irq_chip dummy_irq_chip = {
 108         .name           = "dummy",
 109         .startup        = noop_ret,
 110         .shutdown       = noop,
 111         .enable         = noop,
 112         .disable        = noop,
 113         .ack            = noop,
 114         .mask           = noop,
 115         .unmask         = noop,
 116         .end            = noop,
 117 };
 118
 119 /*
 120  * Special, empty irq handler:
 121  */
 122 irqreturn_t no_action(int cpl, void *dev_id)
 123 {
 124         return IRQ_NONE;
 125 }
 126
 127 /**
 128  * handle_IRQ_event - irq action chain handler
 129  * @irq:        the interrupt number
 130  * @action:     the interrupt action chain for this irq
 131  *
 132  * Handles the action chain of an irq event
 133  */
 134 irqreturn_t handle_IRQ_event(unsigned int irq, struct irqaction *action)
 135 {
 136         irqreturn_t ret, retval = IRQ_NONE;
 137         unsigned int status = 0;
 138
 139         if (!(action->flags & IRQF_DISABLED))
 140                 local_irq_enable_in_hardirq();
 141
 142         do {
 143                 ret = action->handler(irq, action->dev_id);
 144                 if (ret == IRQ_HANDLED)
 145                         status |= action->flags;
 146                 retval |= ret;
 147                 action = action->next;
 148         } while (action);
 149
 150         if (status & IRQF_SAMPLE_RANDOM)
 151                 add_interrupt_randomness(irq);
 152         local_irq_disable();
 153
 154         return retval;
 155 }
 156
 157 #ifndef CONFIG_GENERIC_HARDIRQS_NO__DO_IRQ
 158 /**
 159  * __do_IRQ - original all in one highlevel IRQ handler
 160  * @irq:        the interrupt number
 161  *
 162  * __do_IRQ handles all normal device IRQ's (the special
 163  * SMP cross-CPU interrupts have their own specific
 164  * handlers).
 165  *
 166  * This is the original x86 implementation which is used for every
 167  * interrupt type.
 168  */
 169 unsigned int __do_IRQ(unsigned int irq)
 170 {
 171         struct irq_desc *desc = irq_to_desc(irq);
 172         struct irqaction *action;
 173         unsigned int status;
 174
 175         kstat_incr_irqs_this_cpu(irq, desc);
 176
 177         if (CHECK_IRQ_PER_CPU(desc->status)) {
 178                 irqreturn_t action_ret;
 179
 180                 /*
 181                  * No locking required for CPU-local interrupts:
 182                  */
 183                 if (desc->chip->ack)
 184                         desc->chip->ack(irq);
 185                 if (likely(!(desc->status & IRQ_DISABLED))) {
 186                         action_ret = handle_IRQ_event(irq, desc->action);
 187                         if (!noirqdebug)
 188                                 note_interrupt(irq, desc, action_ret);
 189                 }
 190                 desc->chip->end(irq);
 191                 return 1;
 192         }
 193
 194         spin_lock(&desc->lock);
 195         if (desc->chip->ack)
 196                 desc->chip->ack(irq);
 197         /*
 198          * REPLAY is when Linux resends an IRQ that was dropped earlier
 199          * WAITING is used by probe to mark irqs that are being tested
 200          */
 201         status = desc->status & ~(IRQ_REPLAY | IRQ_WAITING);
 202         status |= IRQ_PENDING; /* we _want_ to handle it */
 203
 204         /*
 205          * If the IRQ is disabled for whatever reason, we cannot
 206          * use the action we have.
 207          */
 208         action = NULL;
 209         if (likely(!(status & (IRQ_DISABLED | IRQ_INPROGRESS)))) {
 210                 action = desc->action;
 211                 status &= ~IRQ_PENDING; /* we commit to handling */
 212                 status |= IRQ_INPROGRESS; /* we are handling it */
 213         }
 214         desc->status = status;
 215
 216         /*
 217          * If there is no IRQ handler or it was disabled, exit early.
 218          * Since we set PENDING, if another processor is handling
 219          * a different instance of this same irq, the other processor
 220          * will take care of it.
 221          */
 222         if (unlikely(!action))
 223                 goto out;
 224
 225         /*
 226          * Edge triggered interrupts need to remember
 227          * pending events.
 228          * This applies to any hw interrupts that allow a second
 229          * instance of the same irq to arrive while we are in do_IRQ
 230          * or in the handler. But the code here only handles the _second_
 231          * instance of the irq, not the third or fourth. So it is mostly
 232          * useful for irq hardware that does not mask cleanly in an
 233          * SMP environment.
 234          */
 235         for (;;) {
 236                 irqreturn_t action_ret;
 237
 238                 spin_unlock(&desc->lock);
 239
 240                 action_ret = handle_IRQ_event(irq, action);
 241                 if (!noirqdebug)
 242                         note_interrupt(irq, desc, action_ret);
 243
 244                 spin_lock(&desc->lock);
 245                 if (likely(!(desc->status & IRQ_PENDING)))
 246                         break;
 247                 desc->status &= ~IRQ_PENDING;
 248         }
 249         desc->status &= ~IRQ_INPROGRESS;
 250
 251 out:
 252         /*
 253          * The ->end() handler has to deal with interrupts which got
 254          * disabled while the handler was running.
 255          */
 256         desc->chip->end(irq);
 257         spin_unlock(&desc->lock);
 258
 259         return 1;
 260 }
 261 #endif
 262
 263
 264 #ifdef CONFIG_TRACE_IRQFLAGS
 265 /*
 266  * lockdep: we want to handle all irq_desc locks as a single lock-class:
 267  */
 268 static struct lock_class_key irq_desc_lock_class;
 269
 270 void early_init_irq_lock_class(void)
 271 {
 272         int i;
 273
 274         for (i = 0; i < nr_irqs; i++)
 275                 lockdep_set_class(&irq_desc[i].lock, &irq_desc_lock_class);
 276 }
 277 #endif