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  */
  24 void fastcall
  25 handle_bad_irq(unsigned int irq, struct irq_desc *desc, struct pt_regs *regs)
  26 {
  27         print_irq_desc(irq, desc);
  28         kstat_this_cpu.irqs[irq]++;
  29         ack_bad_irq(irq);
  30 }
  31
  32 /*
  33  * Linux has a controller-independent interrupt architecture.
  34  * Every controller has a 'controller-template', that is used
  35  * by the main code to do the right thing. Each driver-visible
  36  * interrupt source is transparently wired to the appropriate
  37  * controller. Thus drivers need not be aware of the
  38  * interrupt-controller.
  39  *
  40  * The code is designed to be easily extended with new/different
  41  * interrupt controllers, without having to do assembly magic or
  42  * having to touch the generic code.
  43  *
  44  * Controller mappings for all interrupt sources:
  45  */
  46 struct irq_desc irq_desc[NR_IRQS] __cacheline_aligned = {
  47         [0 ... NR_IRQS-1] = {
  48                 .status = IRQ_DISABLED,
  49                 .chip = &no_irq_chip,
  50                 .handle_irq = handle_bad_irq,
  51                 .depth = 1,
  52                 .lock = SPIN_LOCK_UNLOCKED,
  53 #ifdef CONFIG_SMP
  54                 .affinity = CPU_MASK_ALL
  55 #endif
  56         }
  57 };
  58
  59 /*
  60  * What should we do if we get a hw irq event on an illegal vector?
  61  * Each architecture has to answer this themself.
  62  */
  63 static void ack_bad(unsigned int irq)
  64 {
  65         print_irq_desc(irq, irq_desc + irq);
  66         ack_bad_irq(irq);
  67 }
  68
  69 /*
  70  * NOP functions
  71  */
  72 static void noop(unsigned int irq)
  73 {
  74 }
  75
  76 static unsigned int noop_ret(unsigned int irq)
  77 {
  78         return 0;
  79 }
  80
  81 /*
  82  * Generic no controller implementation
  83  */
  84 struct irq_chip no_irq_chip = {
  85         .name           = "none",
  86         .startup        = noop_ret,
  87         .shutdown       = noop,
  88         .enable         = noop,
  89         .disable        = noop,
  90         .ack            = ack_bad,
  91         .end            = noop,
  92 };
  93
  94 /*
  95  * Special, empty irq handler:
  96  */
  97 irqreturn_t no_action(int cpl, void *dev_id, struct pt_regs *regs)
  98 {
  99         return IRQ_NONE;
 100 }
 101
 102 /**
 103  * handle_IRQ_event - irq action chain handler
 104  * @irq:        the interrupt number
 105  * @regs:       pointer to a register structure
 106  * @action:     the interrupt action chain for this irq
 107  *
 108  * Handles the action chain of an irq event
 109  */
 110 irqreturn_t handle_IRQ_event(unsigned int irq, struct pt_regs *regs,
 111                              struct irqaction *action)
 112 {
 113         irqreturn_t ret, retval = IRQ_NONE;
 114         unsigned int status = 0;
 115
 116         if (!(action->flags & SA_INTERRUPT))
 117                 local_irq_enable();
 118
 119         do {
 120                 ret = action->handler(irq, action->dev_id, regs);
 121                 if (ret == IRQ_HANDLED)
 122                         status |= action->flags;
 123                 retval |= ret;
 124                 action = action->next;
 125         } while (action);
 126
 127         if (status & SA_SAMPLE_RANDOM)
 128                 add_interrupt_randomness(irq);
 129         local_irq_disable();
 130
 131         return retval;
 132 }
 133
 134 /**
 135  * __do_IRQ - original all in one highlevel IRQ handler
 136  * @irq:        the interrupt number
 137  * @regs:       pointer to a register structure
 138  *
 139  * __do_IRQ handles all normal device IRQ's (the special
 140  * SMP cross-CPU interrupts have their own specific
 141  * handlers).
 142  *
 143  * This is the original x86 implementation which is used for every
 144  * interrupt type.
 145  */
 146 fastcall unsigned int __do_IRQ(unsigned int irq, struct pt_regs *regs)
 147 {
 148         struct irq_desc *desc = irq_desc + irq;
 149         struct irqaction *action;
 150         unsigned int status;
 151
 152         kstat_this_cpu.irqs[irq]++;
 153         if (CHECK_IRQ_PER_CPU(desc->status)) {
 154                 irqreturn_t action_ret;
 155
 156                 /*
 157                  * No locking required for CPU-local interrupts:
 158                  */
 159                 if (desc->chip->ack)
 160                         desc->chip->ack(irq);
 161                 action_ret = handle_IRQ_event(irq, regs, desc->action);
 162                 desc->chip->end(irq);
 163                 return 1;
 164         }
 165
 166         spin_lock(&desc->lock);
 167         if (desc->chip->ack)
 168                 desc->chip->ack(irq);
 169         /*
 170          * REPLAY is when Linux resends an IRQ that was dropped earlier
 171          * WAITING is used by probe to mark irqs that are being tested
 172          */
 173         status = desc->status & ~(IRQ_REPLAY | IRQ_WAITING);
 174         status |= IRQ_PENDING; /* we _want_ to handle it */
 175
 176         /*
 177          * If the IRQ is disabled for whatever reason, we cannot
 178          * use the action we have.
 179          */
 180         action = NULL;
 181         if (likely(!(status & (IRQ_DISABLED | IRQ_INPROGRESS)))) {
 182                 action = desc->action;
 183                 status &= ~IRQ_PENDING; /* we commit to handling */
 184                 status |= IRQ_INPROGRESS; /* we are handling it */
 185         }
 186         desc->status = status;
 187
 188         /*
 189          * If there is no IRQ handler or it was disabled, exit early.
 190          * Since we set PENDING, if another processor is handling
 191          * a different instance of this same irq, the other processor
 192          * will take care of it.
 193          */
 194         if (unlikely(!action))
 195                 goto out;
 196
 197         /*
 198          * Edge triggered interrupts need to remember
 199          * pending events.
 200          * This applies to any hw interrupts that allow a second
 201          * instance of the same irq to arrive while we are in do_IRQ
 202          * or in the handler. But the code here only handles the _second_
 203          * instance of the irq, not the third or fourth. So it is mostly
 204          * useful for irq hardware that does not mask cleanly in an
 205          * SMP environment.
 206          */
 207         for (;;) {
 208                 irqreturn_t action_ret;
 209
 210                 spin_unlock(&desc->lock);
 211
 212                 action_ret = handle_IRQ_event(irq, regs, action);
 213
 214                 spin_lock(&desc->lock);
 215                 if (!noirqdebug)
 216                         note_interrupt(irq, desc, action_ret, regs);
 217                 if (likely(!(desc->status & IRQ_PENDING)))
 218                         break;
 219                 desc->status &= ~IRQ_PENDING;
 220         }
 221         desc->status &= ~IRQ_INPROGRESS;
 222
 223 out:
 224         /*
 225          * The ->end() handler has to deal with interrupts which got
 226          * disabled while the handler was running.
 227          */
 228         desc->chip->end(irq);
 229         spin_unlock(&desc->lock);
 230
 231         return 1;
 232 }
 233