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 #if defined(CONFIG_NO_IDLE_HZ) && defined(CONFIG_ARM)
  20 #include <asm/dyntick.h>
  21 #endif
  22
  23 #include "internals.h"
  24
  25 /**
  26  * handle_bad_irq - handle spurious and unhandled irqs
  27  */
  28 void fastcall
  29 handle_bad_irq(unsigned int irq, struct irq_desc *desc, struct pt_regs *regs)
  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 = {
  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,
  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  * Special, empty irq handler:
 100  */
 101 irqreturn_t no_action(int cpl, void *dev_id, struct pt_regs *regs)
 102 {
 103         return IRQ_NONE;
 104 }
 105
 106 /**
 107  * handle_IRQ_event - irq action chain handler
 108  * @irq:        the interrupt number
 109  * @regs:       pointer to a register structure
 110  * @action:     the interrupt action chain for this irq
 111  *
 112  * Handles the action chain of an irq event
 113  */
 114 irqreturn_t handle_IRQ_event(unsigned int irq, struct pt_regs *regs,
 115                              struct irqaction *action)
 116 {
 117         irqreturn_t ret, retval = IRQ_NONE;
 118         unsigned int status = 0;
 119
 120 #if defined(CONFIG_NO_IDLE_HZ) && defined(CONFIG_ARM)
 121         if (!(action->flags & SA_TIMER) && system_timer->dyn_tick != NULL) {
 122                 write_seqlock(&xtime_lock);
 123                 if (system_timer->dyn_tick->state & DYN_TICK_ENABLED)
 124                         system_timer->dyn_tick->handler(irq, 0, regs);
 125                 write_sequnlock(&xtime_lock);
 126         }
 127 #endif
 128
 129         if (!(action->flags & SA_INTERRUPT))
 130                 local_irq_enable();
 131
 132         do {
 133                 ret = action->handler(irq, action->dev_id, regs);
 134                 if (ret == IRQ_HANDLED)
 135                         status |= action->flags;
 136                 retval |= ret;
 137                 action = action->next;
 138         } while (action);
 139
 140         if (status & SA_SAMPLE_RANDOM)
 141                 add_interrupt_randomness(irq);
 142         local_irq_disable();
 143
 144         return retval;
 145 }
 146
 147 /**
 148  * __do_IRQ - original all in one highlevel IRQ handler
 149  * @irq:        the interrupt number
 150  * @regs:       pointer to a register structure
 151  *
 152  * __do_IRQ handles all normal device IRQ's (the special
 153  * SMP cross-CPU interrupts have their own specific
 154  * handlers).
 155  *
 156  * This is the original x86 implementation which is used for every
 157  * interrupt type.
 158  */
 159 fastcall unsigned int __do_IRQ(unsigned int irq, struct pt_regs *regs)
 160 {
 161         struct irq_desc *desc = irq_desc + irq;
 162         struct irqaction *action;
 163         unsigned int status;
 164
 165         kstat_this_cpu.irqs[irq]++;
 166         if (CHECK_IRQ_PER_CPU(desc->status)) {
 167                 irqreturn_t action_ret;
 168
 169                 /*
 170                  * No locking required for CPU-local interrupts:
 171                  */
 172                 if (desc->chip->ack)
 173                         desc->chip->ack(irq);
 174                 action_ret = handle_IRQ_event(irq, regs, desc->action);
 175                 desc->chip->end(irq);
 176                 return 1;
 177         }
 178
 179         spin_lock(&desc->lock);
 180         if (desc->chip->ack)
 181                 desc->chip->ack(irq);
 182         /*
 183          * REPLAY is when Linux resends an IRQ that was dropped earlier
 184          * WAITING is used by probe to mark irqs that are being tested
 185          */
 186         status = desc->status & ~(IRQ_REPLAY | IRQ_WAITING);
 187         status |= IRQ_PENDING; /* we _want_ to handle it */
 188
 189         /*
 190          * If the IRQ is disabled for whatever reason, we cannot
 191          * use the action we have.
 192          */
 193         action = NULL;
 194         if (likely(!(status & (IRQ_DISABLED | IRQ_INPROGRESS)))) {
 195                 action = desc->action;
 196                 status &= ~IRQ_PENDING; /* we commit to handling */
 197                 status |= IRQ_INPROGRESS; /* we are handling it */
 198         }
 199         desc->status = status;
 200
 201         /*
 202          * If there is no IRQ handler or it was disabled, exit early.
 203          * Since we set PENDING, if another processor is handling
 204          * a different instance of this same irq, the other processor
 205          * will take care of it.
 206          */
 207         if (unlikely(!action))
 208                 goto out;
 209
 210         /*
 211          * Edge triggered interrupts need to remember
 212          * pending events.
 213          * This applies to any hw interrupts that allow a second
 214          * instance of the same irq to arrive while we are in do_IRQ
 215          * or in the handler. But the code here only handles the _second_
 216          * instance of the irq, not the third or fourth. So it is mostly
 217          * useful for irq hardware that does not mask cleanly in an
 218          * SMP environment.
 219          */
 220         for (;;) {
 221                 irqreturn_t action_ret;
 222
 223                 spin_unlock(&desc->lock);
 224
 225                 action_ret = handle_IRQ_event(irq, regs, action);
 226
 227                 spin_lock(&desc->lock);
 228                 if (!noirqdebug)
 229                         note_interrupt(irq, desc, action_ret, regs);
 230                 if (likely(!(desc->status & IRQ_PENDING)))
 231                         break;
 232                 desc->status &= ~IRQ_PENDING;
 233         }
 234         desc->status &= ~IRQ_INPROGRESS;
 235
 236 out:
 237         /*
 238          * The ->end() handler has to deal with interrupts which got
 239          * disabled while the handler was running.
 240          */
 241         desc->chip->end(irq);
 242         spin_unlock(&desc->lock);
 243
 244         return 1;
 245 }
 246