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 fastcall
  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 struct irq_desc irq_desc[NR_IRQS] __cacheline_aligned_in_smp = {
  51         [0 ... NR_IRQS-1] = {
  52                 .status = IRQ_DISABLED,
  53                 .chip = &no_irq_chip,
  54                 .handle_irq = handle_bad_irq,
  55                 .depth = 1,
  56                 .lock = __SPIN_LOCK_UNLOCKED(irq_desc->lock),
  57 #ifdef CONFIG_SMP
  58                 .affinity = CPU_MASK_ALL
  59 #endif
  60         }
  61 };
  62
  63 /*
  64  * What should we do if we get a hw irq event on an illegal vector?
  65  * Each architecture has to answer this themself.
  66  */
  67 static void ack_bad(unsigned int irq)
  68 {
  69         print_irq_desc(irq, irq_desc + irq);
  70         ack_bad_irq(irq);
  71 }
  72
  73 /*
  74  * NOP functions
  75  */
  76 static void noop(unsigned int irq)
  77 {
  78 }
  79
  80 static unsigned int noop_ret(unsigned int irq)
  81 {
  82         return 0;
  83 }
  84
  85 /*
  86  * Generic no controller implementation
  87  */
  88 struct irq_chip no_irq_chip = {
  89         .name           = "none",
  90         .startup        = noop_ret,
  91         .shutdown       = noop,
  92         .enable         = noop,
  93         .disable        = noop,
  94         .ack            = ack_bad,
  95         .end            = noop,
  96 };
  97
  98 /*
  99  * Generic dummy implementation which can be used for
 100  * real dumb interrupt sources
 101  */
 102 struct irq_chip dummy_irq_chip = {
 103         .name           = "dummy",
 104         .startup        = noop_ret,
 105         .shutdown       = noop,
 106         .enable         = noop,
 107         .disable        = noop,
 108         .ack            = noop,
 109         .mask           = noop,
 110         .unmask         = noop,
 111         .end            = noop,
 112 };
 113
 114 /*
 115  * Special, empty irq handler:
 116  */
 117 irqreturn_t no_action(int cpl, void *dev_id)
 118 {
 119         return IRQ_NONE;
 120 }
 121
 122 /**
 123  * handle_IRQ_event - irq action chain handler
 124  * @irq:        the interrupt number
 125  * @action:     the interrupt action chain for this irq
 126  *
 127  * Handles the action chain of an irq event
 128  */
 129 irqreturn_t handle_IRQ_event(unsigned int irq, struct irqaction *action)
 130 {
 131         irqreturn_t ret, retval = IRQ_NONE;
 132         unsigned int status = 0;
 133
 134         handle_dynamic_tick(action);
 135
 136         if (!(action->flags & IRQF_DISABLED))
 137                 local_irq_enable_in_hardirq();
 138
 139         do {
 140                 ret = action->handler(irq, action->dev_id);
 141                 if (ret == IRQ_HANDLED)
 142                         status |= action->flags;
 143                 retval |= ret;
 144                 action = action->next;
 145         } while (action);
 146
 147         if (status & IRQF_SAMPLE_RANDOM)
 148                 add_interrupt_randomness(irq);
 149         local_irq_disable();
 150
 151         return retval;
 152 }
 153
 154 #ifndef CONFIG_GENERIC_HARDIRQS_NO__DO_IRQ
 155 /**
 156  * __do_IRQ - original all in one highlevel IRQ handler
 157  * @irq:        the interrupt number
 158  *
 159  * __do_IRQ handles all normal device IRQ's (the special
 160  * SMP cross-CPU interrupts have their own specific
 161  * handlers).
 162  *
 163  * This is the original x86 implementation which is used for every
 164  * interrupt type.
 165  */
 166 fastcall unsigned int __do_IRQ(unsigned int irq)
 167 {
 168         struct irq_desc *desc = irq_desc + irq;
 169         struct irqaction *action;
 170         unsigned int status;
 171
 172         kstat_this_cpu.irqs[irq]++;
 173         if (CHECK_IRQ_PER_CPU(desc->status)) {
 174                 irqreturn_t action_ret;
 175
 176                 /*
 177                  * No locking required for CPU-local interrupts:
 178                  */
 179                 if (desc->chip->ack)
 180                         desc->chip->ack(irq);
 181                 action_ret = handle_IRQ_event(irq, desc->action);
 182                 if (!noirqdebug)
 183                         note_interrupt(irq, desc, action_ret);
 184                 desc->chip->end(irq);
 185                 return 1;
 186         }
 187
 188         spin_lock(&desc->lock);
 189         if (desc->chip->ack)
 190                 desc->chip->ack(irq);
 191         /*
 192          * REPLAY is when Linux resends an IRQ that was dropped earlier
 193          * WAITING is used by probe to mark irqs that are being tested
 194          */
 195         status = desc->status & ~(IRQ_REPLAY | IRQ_WAITING);
 196         status |= IRQ_PENDING; /* we _want_ to handle it */
 197
 198         /*
 199          * If the IRQ is disabled for whatever reason, we cannot
 200          * use the action we have.
 201          */
 202         action = NULL;
 203         if (likely(!(status & (IRQ_DISABLED | IRQ_INPROGRESS)))) {
 204                 action = desc->action;
 205                 status &= ~IRQ_PENDING; /* we commit to handling */
 206                 status |= IRQ_INPROGRESS; /* we are handling it */
 207         }
 208         desc->status = status;
 209
 210         /*
 211          * If there is no IRQ handler or it was disabled, exit early.
 212          * Since we set PENDING, if another processor is handling
 213          * a different instance of this same irq, the other processor
 214          * will take care of it.
 215          */
 216         if (unlikely(!action))
 217                 goto out;
 218
 219         /*
 220          * Edge triggered interrupts need to remember
 221          * pending events.
 222          * This applies to any hw interrupts that allow a second
 223          * instance of the same irq to arrive while we are in do_IRQ
 224          * or in the handler. But the code here only handles the _second_
 225          * instance of the irq, not the third or fourth. So it is mostly
 226          * useful for irq hardware that does not mask cleanly in an
 227          * SMP environment.
 228          */
 229         for (;;) {
 230                 irqreturn_t action_ret;
 231
 232                 spin_unlock(&desc->lock);
 233
 234                 action_ret = handle_IRQ_event(irq, action);
 235                 if (!noirqdebug)
 236                         note_interrupt(irq, desc, action_ret);
 237
 238                 spin_lock(&desc->lock);
 239                 if (likely(!(desc->status & IRQ_PENDING)))
 240                         break;
 241                 desc->status &= ~IRQ_PENDING;
 242         }
 243         desc->status &= ~IRQ_INPROGRESS;
 244
 245 out:
 246         /*
 247          * The ->end() handler has to deal with interrupts which got
 248          * disabled while the handler was running.
 249          */
 250         desc->chip->end(irq);
 251         spin_unlock(&desc->lock);
 252
 253         return 1;
 254 }
 255 #endif
 256
 257 #ifdef CONFIG_TRACE_IRQFLAGS
 258
 259 /*
 260  * lockdep: we want to handle all irq_desc locks as a single lock-class:
 261  */
 262 static struct lock_class_key irq_desc_lock_class;
 263
 264 void early_init_irq_lock_class(void)
 265 {
 266         int i;
 267
 268         for (i = 0; i < NR_IRQS; i++)
 269                 lockdep_set_class(&irq_desc[i].lock, &irq_desc_lock_class);
 270 }
 271
 272 #endif