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

   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