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 handle_bad_irq(unsigned int irq, struct irq_desc *desc)
  29 {
  30         print_irq_desc(irq, desc);
  31         kstat_incr_irqs_this_cpu(irq, desc);
  32         ack_bad_irq(irq);
  33 }
  34
  35 /*
  36  * Linux has a controller-independent interrupt architecture.
  37  * Every controller has a 'controller-template', that is used
  38  * by the main code to do the right thing. Each driver-visible
  39  * interrupt source is transparently wired to the appropriate
  40  * controller. Thus drivers need not be aware of the
  41  * interrupt-controller.
  42  *
  43  * The code is designed to be easily extended with new/different
  44  * interrupt controllers, without having to do assembly magic or
  45  * having to touch the generic code.
  46  *
  47  * Controller mappings for all interrupt sources:
  48  */
  49 int nr_irqs = NR_IRQS;
  50 EXPORT_SYMBOL_GPL(nr_irqs);
  51
  52 struct irq_desc irq_desc[NR_IRQS] __cacheline_aligned_in_smp = {
  53         [0 ... NR_IRQS-1] = {
  54                 .status = IRQ_DISABLED,
  55                 .chip = &no_irq_chip,
  56                 .handle_irq = handle_bad_irq,
  57                 .depth = 1,
  58                 .lock = __SPIN_LOCK_UNLOCKED(irq_desc->lock),
  59 #ifdef CONFIG_SMP
  60                 .affinity = CPU_MASK_ALL
  61 #endif
  62         }
  63 };
  64
  65 /*
  66  * What should we do if we get a hw irq event on an illegal vector?
  67  * Each architecture has to answer this themself.
  68  */
  69 static void ack_bad(unsigned int irq)
  70 {
  71         struct irq_desc *desc = irq_to_desc(irq);
  72
  73         print_irq_desc(irq, desc);
  74         ack_bad_irq(irq);
  75 }
  76
  77 /*
  78  * NOP functions
  79  */
  80 static void noop(unsigned int irq)
  81 {
  82 }
  83
  84 static unsigned int noop_ret(unsigned int irq)
  85 {
  86         return 0;
  87 }
  88
  89 /*
  90  * Generic no controller implementation
  91  */
  92 struct irq_chip no_irq_chip = {
  93         .name           = "none",
  94         .startup        = noop_ret,
  95         .shutdown       = noop,
  96         .enable         = noop,
  97         .disable        = noop,
  98         .ack            = ack_bad,
  99         .end            = noop,
 100 };
 101
 102 /*
 103  * Generic dummy implementation which can be used for
 104  * real dumb interrupt sources
 105  */
 106 struct irq_chip dummy_irq_chip = {
 107         .name           = "dummy",
 108         .startup        = noop_ret,
 109         .shutdown       = noop,
 110         .enable         = noop,
 111         .disable        = noop,
 112         .ack            = noop,
 113         .mask           = noop,
 114         .unmask         = noop,
 115         .end            = noop,
 116 };
 117
 118 /*
 119  * Special, empty irq handler:
 120  */
 121 irqreturn_t no_action(int cpl, void *dev_id)
 122 {
 123         return IRQ_NONE;
 124 }
 125
 126 /**
 127  * handle_IRQ_event - irq action chain handler
 128  * @irq:        the interrupt number
 129  * @action:     the interrupt action chain for this irq
 130  *
 131  * Handles the action chain of an irq event
 132  */
 133 irqreturn_t handle_IRQ_event(unsigned int irq, struct irqaction *action)
 134 {
 135         irqreturn_t ret, retval = IRQ_NONE;
 136         unsigned int status = 0;
 137
 138         if (!(action->flags & IRQF_DISABLED))
 139                 local_irq_enable_in_hardirq();
 140
 141         do {
 142                 ret = action->handler(irq, action->dev_id);
 143                 if (ret == IRQ_HANDLED)
 144                         status |= action->flags;
 145                 retval |= ret;
 146                 action = action->next;
 147         } while (action);
 148
 149         if (status & IRQF_SAMPLE_RANDOM)
 150                 add_interrupt_randomness(irq);
 151         local_irq_disable();
 152
 153         return retval;
 154 }
 155
 156 #ifndef CONFIG_GENERIC_HARDIRQS_NO__DO_IRQ
 157 /**
 158  * __do_IRQ - original all in one highlevel IRQ handler
 159  * @irq:        the interrupt number
 160  *
 161  * __do_IRQ handles all normal device IRQ's (the special
 162  * SMP cross-CPU interrupts have their own specific
 163  * handlers).
 164  *
 165  * This is the original x86 implementation which is used for every
 166  * interrupt type.
 167  */
 168 unsigned int __do_IRQ(unsigned int irq)
 169 {
 170         struct irq_desc *desc = irq_to_desc(irq);
 171         struct irqaction *action;
 172         unsigned int status;
 173
 174         kstat_incr_irqs_this_cpu(irq, desc);
 175
 176         if (CHECK_IRQ_PER_CPU(desc->status)) {
 177                 irqreturn_t action_ret;
 178
 179                 /*
 180                  * No locking required for CPU-local interrupts:
 181                  */
 182                 if (desc->chip->ack)
 183                         desc->chip->ack(irq);
 184                 if (likely(!(desc->status & IRQ_DISABLED))) {
 185                         action_ret = handle_IRQ_event(irq, desc->action);
 186                         if (!noirqdebug)
 187                                 note_interrupt(irq, desc, action_ret);
 188                 }
 189                 desc->chip->end(irq);
 190                 return 1;
 191         }
 192
 193         spin_lock(&desc->lock);
 194         if (desc->chip->ack)
 195                 desc->chip->ack(irq);
 196         /*
 197          * REPLAY is when Linux resends an IRQ that was dropped earlier
 198          * WAITING is used by probe to mark irqs that are being tested
 199          */
 200         status = desc->status & ~(IRQ_REPLAY | IRQ_WAITING);
 201         status |= IRQ_PENDING; /* we _want_ to handle it */
 202
 203         /*
 204          * If the IRQ is disabled for whatever reason, we cannot
 205          * use the action we have.
 206          */
 207         action = NULL;
 208         if (likely(!(status & (IRQ_DISABLED | IRQ_INPROGRESS)))) {
 209                 action = desc->action;
 210                 status &= ~IRQ_PENDING; /* we commit to handling */
 211                 status |= IRQ_INPROGRESS; /* we are handling it */
 212         }
 213         desc->status = status;
 214
 215         /*
 216          * If there is no IRQ handler or it was disabled, exit early.
 217          * Since we set PENDING, if another processor is handling
 218          * a different instance of this same irq, the other processor
 219          * will take care of it.
 220          */
 221         if (unlikely(!action))
 222                 goto out;
 223
 224         /*
 225          * Edge triggered interrupts need to remember
 226          * pending events.
 227          * This applies to any hw interrupts that allow a second
 228          * instance of the same irq to arrive while we are in do_IRQ
 229          * or in the handler. But the code here only handles the _second_
 230          * instance of the irq, not the third or fourth. So it is mostly
 231          * useful for irq hardware that does not mask cleanly in an
 232          * SMP environment.
 233          */
 234         for (;;) {
 235                 irqreturn_t action_ret;
 236
 237                 spin_unlock(&desc->lock);
 238
 239                 action_ret = handle_IRQ_event(irq, action);
 240                 if (!noirqdebug)
 241                         note_interrupt(irq, desc, action_ret);
 242
 243                 spin_lock(&desc->lock);
 244                 if (likely(!(desc->status & IRQ_PENDING)))
 245                         break;
 246                 desc->status &= ~IRQ_PENDING;
 247         }
 248         desc->status &= ~IRQ_INPROGRESS;
 249
 250 out:
 251         /*
 252          * The ->end() handler has to deal with interrupts which got
 253          * disabled while the handler was running.
 254          */
 255         desc->chip->end(irq);
 256         spin_unlock(&desc->lock);
 257
 258         return 1;
 259 }
 260 #endif
 261
 262
 263 #ifdef CONFIG_TRACE_IRQFLAGS
 264 /*
 265  * lockdep: we want to handle all irq_desc locks as a single lock-class:
 266  */
 267 static struct lock_class_key irq_desc_lock_class;
 268
 269 void early_init_irq_lock_class(void)
 270 {
 271         struct irq_desc *desc;
 272         int i;
 273
 274         for_each_irq_desc(i, desc)
 275                 lockdep_set_class(&desc->lock, &irq_desc_lock_class);
 276 }
 277 #endif