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
18 static int irq = -1;
19
dummy_interrupt(int irq,void * dev_id)20 static 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
dummy_irq_init(void)33 static 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
dummy_irq_exit(void)47 static void __exit dummy_irq_exit(void)
48 {
49 printk(KERN_INFO "dummy-irq unloaded\n");
50 free_irq(irq, &irq);
51 }
52
53 module_init(dummy_irq_init);
54 module_exit(dummy_irq_exit);
55
56 MODULE_LICENSE("GPL");
57 MODULE_AUTHOR("Jiri Kosina");
58 module_param_hw(irq, uint, irq, 0444);
59 MODULE_PARM_DESC(irq, "The IRQ to register for");
60 MODULE_DESCRIPTION("Dummy IRQ handler driver");
61