LXR linux/drivers/misc/dummy-irq.c

   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
  22static int irq = -1;
  23
  24static 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
  37static 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
  51static void __exit dummy_irq_exit(void)
  52{
  53        printk(KERN_INFO "dummy-irq unloaded\n");
  54        free_irq(irq, &irq);
  55}
  56
  57module_init(dummy_irq_init);
  58module_exit(dummy_irq_exit);
  59
  60MODULE_LICENSE("GPL");
  61MODULE_AUTHOR("Jiri Kosina");
  62module_param_hw(irq, uint, irq, 0444);
  63MODULE_PARM_DESC(irq, "The IRQ to register for");
  64MODULE_DESCRIPTION("Dummy IRQ handler driver");
  65