resend.c

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/*
 * linux/kernel/irq/resend.c
 *
 * Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
 * Copyright (C) 2005-2006, Thomas Gleixner
 *
 * This file contains the IRQ-resend code
 *
 * If the interrupt is waiting to be processed, we try to re-run it.
 * We can't directly run it from here since the caller might be in an
 * interrupt-protected region. Not all irq controller chips can
 * retrigger interrupts at the hardware level, so in those cases
 * we allow the resending of IRQs via a tasklet.
 */

#include <linux/irq.h>
#include <linux/module.h>
#include <linux/random.h>
#include <linux/interrupt.h>

#include "internals.h"

#ifdef CONFIG_HARDIRQS_SW_RESEND

/* Bitmap to handle software resend of interrupts: */
static DECLARE_BITMAP(irqs_resend, IRQ_BITMAP_BITS);

/*
 * Run software resends of IRQ's
 */
static void resend_irqs(unsigned long arg)
{
    struct irq_desc *desc;
    int irq;

    while (!bitmap_empty(irqs_resend, nr_irqs)) {
        irq = find_first_bit(irqs_resend, nr_irqs);
        clear_bit(irq, irqs_resend);
        desc = irq_to_desc(irq);
        local_irq_disable();
        desc->handle_irq(irq, desc);
        local_irq_enable();
    }
}

/* Tasklet to handle resend: */
static DECLARE_TASKLET(resend_tasklet, resend_irqs, 0);

#endif

/*
 * IRQ resend
 *
 * Is called with interrupts disabled and desc->lock held.
 */
void check_irq_resend(struct irq_desc *desc, unsigned int irq)
{
    /*
     * We do not resend level type interrupts. Level type
     * interrupts are resent by hardware when they are still
     * active. Clear the pending bit so suspend/resume does not
     * get confused.
     */
    if (irq_settings_is_level(desc)) {
        desc->istate &= ~IRQS_PENDING;
        return;
    }
    if (desc->istate & IRQS_REPLAY)
        return;
    if (desc->istate & IRQS_PENDING) {
        desc->istate &= ~IRQS_PENDING;
        desc->istate |= IRQS_REPLAY;

        if (!desc->irq_data.chip->irq_retrigger ||
            !desc->irq_data.chip->irq_retrigger(&desc->irq_data)) {
#ifdef CONFIG_HARDIRQS_SW_RESEND
            /* Set it pending and activate the softirq: */
            set_bit(irq, irqs_resend);
            tasklet_schedule(&resend_tasklet);
#endif
        }
    }
}