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/random.h>
  15 #include <linux/sched.h>
  16 #include <linux/interrupt.h>
  17 #include <linux/kernel_stat.h>
  18
  19 #include <trace/events/irq.h>
  20
  21 #include "internals.h"
  22
  23 /**
  24  * handle_bad_irq - handle spurious and unhandled irqs
  25  * @irq:       the interrupt number
  26  * @desc:      description of the interrupt
  27  *
  28  * Handles spurious and unhandled IRQ's. It also prints a debugmessage.
  29  */
  30 void handle_bad_irq(unsigned int irq, struct irq_desc *desc)
  31 {
  32         print_irq_desc(irq, desc);
  33         kstat_incr_irqs_this_cpu(irq, desc);
  34         ack_bad_irq(irq);
  35 }
  36
  37 /*
  38  * Special, empty irq handler:
  39  */
  40 irqreturn_t no_action(int cpl, void *dev_id)
  41 {
  42         return IRQ_NONE;
  43 }
  44
  45 static void warn_no_thread(unsigned int irq, struct irqaction *action)
  46 {
  47         if (test_and_set_bit(IRQTF_WARNED, &action->thread_flags))
  48                 return;
  49
  50         printk(KERN_WARNING "IRQ %d device %s returned IRQ_WAKE_THREAD "
  51                "but no thread function available.", irq, action->name);
  52 }
  53
  54 /**
  55  * handle_IRQ_event - irq action chain handler
  56  * @irq:        the interrupt number
  57  * @action:     the interrupt action chain for this irq
  58  *
  59  * Handles the action chain of an irq event
  60  */
  61 irqreturn_t handle_IRQ_event(unsigned int irq, struct irqaction *action)
  62 {
  63         irqreturn_t ret, retval = IRQ_NONE;
  64         unsigned int status = 0;
  65
  66         do {
  67                 trace_irq_handler_entry(irq, action);
  68                 ret = action->handler(irq, action->dev_id);
  69                 trace_irq_handler_exit(irq, action, ret);
  70
  71                 switch (ret) {
  72                 case IRQ_WAKE_THREAD:
  73                         /*
  74                          * Set result to handled so the spurious check
  75                          * does not trigger.
  76                          */
  77                         ret = IRQ_HANDLED;
  78
  79                         /*
  80                          * Catch drivers which return WAKE_THREAD but
  81                          * did not set up a thread function
  82                          */
  83                         if (unlikely(!action->thread_fn)) {
  84                                 warn_no_thread(irq, action);
  85                                 break;
  86                         }
  87
  88                         /*
  89                          * Wake up the handler thread for this
  90                          * action. In case the thread crashed and was
  91                          * killed we just pretend that we handled the
  92                          * interrupt. The hardirq handler above has
  93                          * disabled the device interrupt, so no irq
  94                          * storm is lurking.
  95                          */
  96                         if (likely(!test_bit(IRQTF_DIED,
  97                                              &action->thread_flags))) {
  98                                 set_bit(IRQTF_RUNTHREAD, &action->thread_flags);
  99                                 wake_up_process(action->thread);
 100                         }
 101
 102                         /* Fall through to add to randomness */
 103                 case IRQ_HANDLED:
 104                         status |= action->flags;
 105                         break;
 106
 107                 default:
 108                         break;
 109                 }
 110
 111                 retval |= ret;
 112                 action = action->next;
 113         } while (action);
 114
 115         if (status & IRQF_SAMPLE_RANDOM)
 116                 add_interrupt_randomness(irq);
 117         local_irq_disable();
 118
 119         return retval;
 120 }
 121
 122 #ifndef CONFIG_GENERIC_HARDIRQS_NO__DO_IRQ
 123
 124 #ifdef CONFIG_ENABLE_WARN_DEPRECATED
 125 # warning __do_IRQ is deprecated. Please convert to proper flow handlers
 126 #endif
 127
 128 /**
 129  * __do_IRQ - original all in one highlevel IRQ handler
 130  * @irq:        the interrupt number
 131  *
 132  * __do_IRQ handles all normal device IRQ's (the special
 133  * SMP cross-CPU interrupts have their own specific
 134  * handlers).
 135  *
 136  * This is the original x86 implementation which is used for every
 137  * interrupt type.
 138  */
 139 unsigned int __do_IRQ(unsigned int irq)
 140 {
 141         struct irq_desc *desc = irq_to_desc(irq);
 142         struct irqaction *action;
 143         unsigned int status;
 144
 145         kstat_incr_irqs_this_cpu(irq, desc);
 146
 147         if (CHECK_IRQ_PER_CPU(desc->status)) {
 148                 irqreturn_t action_ret;
 149
 150                 /*
 151                  * No locking required for CPU-local interrupts:
 152                  */
 153                 if (desc->irq_data.chip->ack)
 154                         desc->irq_data.chip->ack(irq);
 155                 if (likely(!(desc->status & IRQ_DISABLED))) {
 156                         action_ret = handle_IRQ_event(irq, desc->action);
 157                         if (!noirqdebug)
 158                                 note_interrupt(irq, desc, action_ret);
 159                 }
 160                 desc->irq_data.chip->end(irq);
 161                 return 1;
 162         }
 163
 164         raw_spin_lock(&desc->lock);
 165         if (desc->irq_data.chip->ack)
 166                 desc->irq_data.chip->ack(irq);
 167         /*
 168          * REPLAY is when Linux resends an IRQ that was dropped earlier
 169          * WAITING is used by probe to mark irqs that are being tested
 170          */
 171         status = desc->status & ~(IRQ_REPLAY | IRQ_WAITING);
 172         status |= IRQ_PENDING; /* we _want_ to handle it */
 173
 174         /*
 175          * If the IRQ is disabled for whatever reason, we cannot
 176          * use the action we have.
 177          */
 178         action = NULL;
 179         if (likely(!(status & (IRQ_DISABLED | IRQ_INPROGRESS)))) {
 180                 action = desc->action;
 181                 status &= ~IRQ_PENDING; /* we commit to handling */
 182                 status |= IRQ_INPROGRESS; /* we are handling it */
 183         }
 184         desc->status = status;
 185
 186         /*
 187          * If there is no IRQ handler or it was disabled, exit early.
 188          * Since we set PENDING, if another processor is handling
 189          * a different instance of this same irq, the other processor
 190          * will take care of it.
 191          */
 192         if (unlikely(!action))
 193                 goto out;
 194
 195         /*
 196          * Edge triggered interrupts need to remember
 197          * pending events.
 198          * This applies to any hw interrupts that allow a second
 199          * instance of the same irq to arrive while we are in do_IRQ
 200          * or in the handler. But the code here only handles the _second_
 201          * instance of the irq, not the third or fourth. So it is mostly
 202          * useful for irq hardware that does not mask cleanly in an
 203          * SMP environment.
 204          */
 205         for (;;) {
 206                 irqreturn_t action_ret;
 207
 208                 raw_spin_unlock(&desc->lock);
 209
 210                 action_ret = handle_IRQ_event(irq, action);
 211                 if (!noirqdebug)
 212                         note_interrupt(irq, desc, action_ret);
 213
 214                 raw_spin_lock(&desc->lock);
 215                 if (likely(!(desc->status & IRQ_PENDING)))
 216                         break;
 217                 desc->status &= ~IRQ_PENDING;
 218         }
 219         desc->status &= ~IRQ_INPROGRESS;
 220
 221 out:
 222         /*
 223          * The ->end() handler has to deal with interrupts which got
 224          * disabled while the handler was running.
 225          */
 226         desc->irq_data.chip->end(irq);
 227         raw_spin_unlock(&desc->lock);
 228
 229         return 1;
 230 }
 231 #endif