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  * Generic dummy implementation which can be used for
  96  * real dumb interrupt sources
  97  */
  98 struct irq_chip dummy_irq_chip = {
  99         .name           = "dummy",
 100         .startup        = noop_ret,
 101         .shutdown       = noop,
 102         .enable         = noop,
 103         .disable        = noop,
 104         .ack            = noop,
 105         .mask           = noop,
 106         .unmask         = noop,
 107         .end            = noop,
 108 };
 109
 110 /*
 111  * Special, empty irq handler:
 112  */
 113 irqreturn_t no_action(int cpl, void *dev_id, struct pt_regs *regs)
 114 {
 115         return IRQ_NONE;
 116 }
 117
 118 /**
 119  * handle_IRQ_event - irq action chain handler
 120  * @irq:        the interrupt number
 121  * @regs:       pointer to a register structure
 122  * @action:     the interrupt action chain for this irq
 123  *
 124  * Handles the action chain of an irq event
 125  */
 126 irqreturn_t handle_IRQ_event(unsigned int irq, struct pt_regs *regs,
 127                              struct irqaction *action)
 128 {
 129         irqreturn_t ret, retval = IRQ_NONE;
 130         unsigned int status = 0;
 131
 132         handle_dynamic_tick(action);
 133
 134         if (!(action->flags & IRQF_DISABLED))
 135                 local_irq_enable();
 136
 137         do {
 138                 ret = action->handler(irq, action->dev_id, regs);
 139                 if (ret == IRQ_HANDLED)
 140                         status |= action->flags;
 141                 retval |= ret;
 142                 action = action->next;
 143         } while (action);
 144
 145         if (status & IRQF_SAMPLE_RANDOM)
 146                 add_interrupt_randomness(irq);
 147         local_irq_disable();
 148
 149         return retval;
 150 }
 151
 152 /**
 153  * __do_IRQ - original all in one highlevel IRQ handler
 154  * @irq:        the interrupt number
 155  * @regs:       pointer to a register structure
 156  *
 157  * __do_IRQ handles all normal device IRQ's (the special
 158  * SMP cross-CPU interrupts have their own specific
 159  * handlers).
 160  *
 161  * This is the original x86 implementation which is used for every
 162  * interrupt type.
 163  */
 164 fastcall unsigned int __do_IRQ(unsigned int irq, struct pt_regs *regs)
 165 {
 166         struct irq_desc *desc = irq_desc + irq;
 167         struct irqaction *action;
 168         unsigned int status;
 169
 170         kstat_this_cpu.irqs[irq]++;
 171         if (CHECK_IRQ_PER_CPU(desc->status)) {
 172                 irqreturn_t action_ret;
 173
 174                 /*
 175                  * No locking required for CPU-local interrupts:
 176                  */
 177                 if (desc->chip->ack)
 178                         desc->chip->ack(irq);
 179                 action_ret = handle_IRQ_event(irq, regs, desc->action);
 180                 desc->chip->end(irq);
 181                 return 1;
 182         }
 183
 184         spin_lock(&desc->lock);
 185         if (desc->chip->ack)
 186                 desc->chip->ack(irq);
 187         /*
 188          * REPLAY is when Linux resends an IRQ that was dropped earlier
 189          * WAITING is used by probe to mark irqs that are being tested
 190          */
 191         status = desc->status & ~(IRQ_REPLAY | IRQ_WAITING);
 192         status |= IRQ_PENDING; /* we _want_ to handle it */
 193
 194         /*
 195          * If the IRQ is disabled for whatever reason, we cannot
 196          * use the action we have.
 197          */
 198         action = NULL;
 199         if (likely(!(status & (IRQ_DISABLED | IRQ_INPROGRESS)))) {
 200                 action = desc->action;
 201                 status &= ~IRQ_PENDING; /* we commit to handling */
 202                 status |= IRQ_INPROGRESS; /* we are handling it */
 203         }
 204         desc->status = status;
 205
 206         /*
 207          * If there is no IRQ handler or it was disabled, exit early.
 208          * Since we set PENDING, if another processor is handling
 209          * a different instance of this same irq, the other processor
 210          * will take care of it.
 211          */
 212         if (unlikely(!action))
 213                 goto out;
 214
 215         /*
 216          * Edge triggered interrupts need to remember
 217          * pending events.
 218          * This applies to any hw interrupts that allow a second
 219          * instance of the same irq to arrive while we are in do_IRQ
 220          * or in the handler. But the code here only handles the _second_
 221          * instance of the irq, not the third or fourth. So it is mostly
 222          * useful for irq hardware that does not mask cleanly in an
 223          * SMP environment.
 224          */
 225         for (;;) {
 226                 irqreturn_t action_ret;
 227
 228                 spin_unlock(&desc->lock);
 229
 230                 action_ret = handle_IRQ_event(irq, regs, action);
 231
 232                 spin_lock(&desc->lock);
 233                 if (!noirqdebug)
 234                         note_interrupt(irq, desc, action_ret, regs);
 235                 if (likely(!(desc->status & IRQ_PENDING)))
 236                         break;
 237                 desc->status &= ~IRQ_PENDING;
 238         }
 239         desc->status &= ~IRQ_INPROGRESS;
 240
 241 out:
 242         /*
 243          * The ->end() handler has to deal with interrupts which got
 244          * disabled while the handler was running.
 245          */
 246         desc->chip->end(irq);
 247         spin_unlock(&desc->lock);
 248
 249         return 1;
 250 }
 251