1 /*
2 * Dummy IRQ handler driver.
3 *
4 * This module only registers itself as a handler that is specified to it
5 * by the 'irq' parameter.
6 *
7 * The sole purpose of this module is to help with debugging of systems on
8 * which spurious IRQs would happen on disabled IRQ vector.
9 *
10 * Copyright (C) 2013 Jiri Kosina
11 */
12
13 /*
14 * This program is free software; you can redistribute it and/or modify it
15 * under the terms of the GNU General Public License version 2 as published by
16 * the Free Software Foundation.
17 */
18 #include <linux/module.h>
19 #include <linux/irq.h>
20 #include <linux/interrupt.h>
21
22 static int irq = -1;
23
dummy_interrupt(int irq,void * dev_id)24 static irqreturn_t dummy_interrupt(int irq, void *dev_id)
25 {
26 static int count = 0;
27
28 if (count == 0) {
29 printk(KERN_INFO "dummy-irq: interrupt occurred on IRQ %d\n",
30 irq);
31 count++;
32 }
33
34 return IRQ_NONE;
35 }
36
dummy_irq_init(void)37 static int __init dummy_irq_init(void)
38 {
39 if (irq < 0) {
40 printk(KERN_ERR "dummy-irq: no IRQ given. Use irq=N\n");
41 return -EIO;
42 }
43 if (request_irq(irq, &dummy_interrupt, IRQF_SHARED, "dummy_irq", &irq)) {
44 printk(KERN_ERR "dummy-irq: cannot register IRQ %d\n", irq);
45 return -EIO;
46 }
47 printk(KERN_INFO "dummy-irq: registered for IRQ %d\n", irq);
48 return 0;
49 }
50
dummy_irq_exit(void)51 static void __exit dummy_irq_exit(void)
52 {
53 printk(KERN_INFO "dummy-irq unloaded\n");
54 free_irq(irq, &irq);
55 }
56
57 module_init(dummy_irq_init);
58 module_exit(dummy_irq_exit);
59
60 MODULE_LICENSE("GPL");
61 MODULE_AUTHOR("Jiri Kosina");
62 module_param_hw(irq, uint, irq, 0444);
63 MODULE_PARM_DESC(irq, "The IRQ to register for");
64 MODULE_DESCRIPTION("Dummy IRQ handler driver");
65