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  * 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, struct pt_regs *regs)
 118 {
 119         return IRQ_NONE;
 120 }
 121
 122 /**
 123  * handle_IRQ_event - irq action chain handler
 124  * @irq:        the interrupt number
 125  * @regs:       pointer to a register structure
 126  * @action:     the interrupt action chain for this irq
 127  *
 128  * Handles the action chain of an irq event
 129  */
 130 irqreturn_t handle_IRQ_event(unsigned int irq, struct pt_regs *regs,
 131                              struct irqaction *action)
 132 {
 133         irqreturn_t ret, retval = IRQ_NONE;
 134         unsigned int status = 0;
 135
 136 #if defined(CONFIG_NO_IDLE_HZ) && defined(CONFIG_ARM)
 137         if (!(action->flags & SA_TIMER) && system_timer->dyn_tick != NULL) {
 138                 write_seqlock(&xtime_lock);
 139                 if (system_timer->dyn_tick->state & DYN_TICK_ENABLED)
 140                         system_timer->dyn_tick->handler(irq, 0, regs);
 141                 write_sequnlock(&xtime_lock);
 142         }
 143 #endif
 144
 145         if (!(action->flags & SA_INTERRUPT))
 146                 local_irq_enable();
 147
 148         do {
 149                 ret = action->handler(irq, action->dev_id, regs);
 150                 if (ret == IRQ_HANDLED)
 151                         status |= action->flags;
 152                 retval |= ret;
 153                 action = action->next;
 154         } while (action);
 155
 156         if (status & SA_SAMPLE_RANDOM)
 157                 add_interrupt_randomness(irq);
 158         local_irq_disable();
 159
 160         return retval;
 161 }
 162
 163 /**
 164  * __do_IRQ - original all in one highlevel IRQ handler
 165  * @irq:        the interrupt number
 166  * @regs:       pointer to a register structure
 167  *
 168  * __do_IRQ handles all normal device IRQ's (the special
 169  * SMP cross-CPU interrupts have their own specific
 170  * handlers).
 171  *
 172  * This is the original x86 implementation which is used for every
 173  * interrupt type.
 174  */
 175 fastcall unsigned int __do_IRQ(unsigned int irq, struct pt_regs *regs)
 176 {
 177         struct irq_desc *desc = irq_desc + irq;
 178         struct irqaction *action;
 179         unsigned int status;
 180
 181         kstat_this_cpu.irqs[irq]++;
 182         if (CHECK_IRQ_PER_CPU(desc->status)) {
 183                 irqreturn_t action_ret;
 184
 185                 /*
 186                  * No locking required for CPU-local interrupts:
 187                  */
 188                 if (desc->chip->ack)
 189                         desc->chip->ack(irq);
 190                 action_ret = handle_IRQ_event(irq, regs, desc->action);
 191                 desc->chip->end(irq);
 192                 return 1;
 193         }
 194
 195         spin_lock(&desc->lock);
 196         if (desc->chip->ack)
 197                 desc->chip->ack(irq);
 198         /*
 199          * REPLAY is when Linux resends an IRQ that was dropped earlier
 200          * WAITING is used by probe to mark irqs that are being tested
 201          */
 202         status = desc->status & ~(IRQ_REPLAY | IRQ_WAITING);
 203         status |= IRQ_PENDING; /* we _want_ to handle it */
 204
 205         /*
 206          * If the IRQ is disabled for whatever reason, we cannot
 207          * use the action we have.
 208          */
 209         action = NULL;
 210         if (likely(!(status & (IRQ_DISABLED | IRQ_INPROGRESS)))) {
 211                 action = desc->action;
 212                 status &= ~IRQ_PENDING; /* we commit to handling */
 213                 status |= IRQ_INPROGRESS; /* we are handling it */
 214         }
 215         desc->status = status;
 216
 217         /*
 218          * If there is no IRQ handler or it was disabled, exit early.
 219          * Since we set PENDING, if another processor is handling
 220          * a different instance of this same irq, the other processor
 221          * will take care of it.
 222          */
 223         if (unlikely(!action))
 224                 goto out;
 225
 226         /*
 227          * Edge triggered interrupts need to remember
 228          * pending events.
 229          * This applies to any hw interrupts that allow a second
 230          * instance of the same irq to arrive while we are in do_IRQ
 231          * or in the handler. But the code here only handles the _second_
 232          * instance of the irq, not the third or fourth. So it is mostly
 233          * useful for irq hardware that does not mask cleanly in an
 234          * SMP environment.
 235          */
 236         for (;;) {
 237                 irqreturn_t action_ret;
 238
 239                 spin_unlock(&desc->lock);
 240
 241                 action_ret = handle_IRQ_event(irq, regs, action);
 242
 243                 spin_lock(&desc->lock);
 244                 if (!noirqdebug)
 245                         note_interrupt(irq, desc, action_ret, regs);
 246                 if (likely(!(desc->status & IRQ_PENDING)))
 247                         break;
 248                 desc->status &= ~IRQ_PENDING;
 249         }
 250         desc->status &= ~IRQ_INPROGRESS;
 251
 252 out:
 253         /*
 254          * The ->end() handler has to deal with interrupts which got
 255          * disabled while the handler was running.
 256          */
 257         desc->chip->end(irq);
 258         spin_unlock(&desc->lock);
 259
 260         return 1;
 261 }
 262