1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Dummy IRQ handler driver.
4 *
5 * This module only registers itself as a handler that is specified to it
6 * by the 'irq' parameter.
7 *
8 * The sole purpose of this module is to help with debugging of systems on
9 * which spurious IRQs would happen on disabled IRQ vector.
10 *
11 * Copyright (C) 2013 Jiri Kosina
12 */
13
14#include <linux/module.h>
15#include <linux/irq.h>
16#include <linux/interrupt.h>
17
18static int irq = -1;
19
20static irqreturn_t dummy_interrupt(int irq, void *dev_id)
21{
22	static int count = 0;
23
24	if (count == 0) {
25		printk(KERN_INFO "dummy-irq: interrupt occurred on IRQ %d\n",
26				irq);
27		count++;
28	}
29
30	return IRQ_NONE;
31}
32
33static int __init dummy_irq_init(void)
34{
35	if (irq < 0) {
36		printk(KERN_ERR "dummy-irq: no IRQ given.  Use irq=N\n");
37		return -EIO;
38	}
39	if (request_irq(irq, &dummy_interrupt, IRQF_SHARED, "dummy_irq", &irq)) {
40		printk(KERN_ERR "dummy-irq: cannot register IRQ %d\n", irq);
41		return -EIO;
42	}
43	printk(KERN_INFO "dummy-irq: registered for IRQ %d\n", irq);
44	return 0;
45}
46
47static void __exit dummy_irq_exit(void)
48{
49	printk(KERN_INFO "dummy-irq unloaded\n");
50	free_irq(irq, &irq);
51}
52
53module_init(dummy_irq_init);
54module_exit(dummy_irq_exit);
55
56MODULE_LICENSE("GPL");
57MODULE_AUTHOR("Jiri Kosina");
58module_param_hw(irq, uint, irq, 0444);
59MODULE_PARM_DESC(irq, "The IRQ to register for");
60MODULE_DESCRIPTION("Dummy IRQ handler driver");
61