root/kernel/irq/dummychip.c
// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
 * Copyright (C) 2005-2006, Thomas Gleixner, Russell King
 *
 * This file contains the dummy interrupt chip implementation
 */
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/export.h>

#include "internals.h"

/*
 * What should we do if we get a hw irq event on an illegal vector?
 * Each architecture has to answer this themselves.
 */
static void ack_bad(struct irq_data *data)
{
        struct irq_desc *desc = irq_data_to_desc(data);

        print_irq_desc(data->irq, desc);
        ack_bad_irq(data->irq);
}

/*
 * NOP functions
 */
static void noop(struct irq_data *data) { }

static unsigned int noop_ret(struct irq_data *data)
{
        return 0;
}

/*
 * Generic no controller implementation
 */
struct irq_chip no_irq_chip = {
        .name           = "none",
        .irq_startup    = noop_ret,
        .irq_shutdown   = noop,
        .irq_enable     = noop,
        .irq_disable    = noop,
        .irq_ack        = ack_bad,
        .flags          = IRQCHIP_SKIP_SET_WAKE,
};

/*
 * Generic dummy implementation which can be used for
 * real dumb interrupt sources
 */
struct irq_chip dummy_irq_chip = {
        .name           = "dummy",
        .irq_startup    = noop_ret,
        .irq_shutdown   = noop,
        .irq_enable     = noop,
        .irq_disable    = noop,
        .irq_ack        = noop,
        .irq_mask       = noop,
        .irq_unmask     = noop,
        .flags          = IRQCHIP_SKIP_SET_WAKE,
};
EXPORT_SYMBOL_GPL(dummy_irq_chip);