LXR linux/kernel/irq/resend.c

   1/*
   2 * linux/kernel/irq/resend.c
   3 *
   4 * Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
   5 * Copyright (C) 2005-2006, Thomas Gleixner
   6 *
   7 * This file contains the IRQ-resend code
   8 *
   9 * If the interrupt is waiting to be processed, we try to re-run it.
  10 * We can't directly run it from here since the caller might be in an
  11 * interrupt-protected region. Not all irq controller chips can
  12 * retrigger interrupts at the hardware level, so in those cases
  13 * we allow the resending of IRQs via a tasklet.
  14 */
  15
  16#include <linux/irq.h>
  17#include <linux/module.h>
  18#include <linux/random.h>
  19#include <linux/interrupt.h>
  20
  21#include "internals.h"
  22
  23#ifdef CONFIG_HARDIRQS_SW_RESEND
  24
  25/* Bitmap to handle software resend of interrupts: */
  26static DECLARE_BITMAP(irqs_resend, NR_IRQS);
  27
  28/*
  29 * Run software resends of IRQ's
  30 */
  31static void resend_irqs(unsigned long arg)
  32{
  33        struct irq_desc *desc;
  34        int irq;
  35
  36        while (!bitmap_empty(irqs_resend, nr_irqs)) {
  37                irq = find_first_bit(irqs_resend, nr_irqs);
  38                clear_bit(irq, irqs_resend);
  39                desc = irq_to_desc(irq);
  40                local_irq_disable();
  41                desc->handle_irq(irq, desc);
  42                local_irq_enable();
  43        }
  44}
  45
  46/* Tasklet to handle resend: */
  47static DECLARE_TASKLET(resend_tasklet, resend_irqs, 0);
  48
  49#endif
  50
  51/*
  52 * IRQ resend
  53 *
  54 * Is called with interrupts disabled and desc->lock held.
  55 */
  56void check_irq_resend(struct irq_desc *desc, unsigned int irq)
  57{
  58        unsigned int status = desc->status;
  59
  60        /*
  61         * Make sure the interrupt is enabled, before resending it:
  62         */
  63        desc->chip->enable(irq);
  64
  65        /*
  66         * We do not resend level type interrupts. Level type
  67         * interrupts are resent by hardware when they are still
  68         * active.
  69         */
  70        if ((status & (IRQ_LEVEL | IRQ_PENDING | IRQ_REPLAY)) == IRQ_PENDING) {
  71                desc->status = (status & ~IRQ_PENDING) | IRQ_REPLAY;
  72
  73                if (!desc->chip->retrigger || !desc->chip->retrigger(irq)) {
  74#ifdef CONFIG_HARDIRQS_SW_RESEND
  75                        /* Set it pending and activate the softirq: */
  76                        set_bit(irq, irqs_resend);
  77                        tasklet_schedule(&resend_tasklet);
  78#endif
  79                }
  80        }
  81}
  82