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authorJiri Kosina <jkosina@suse.cz>2013-03-21 00:21:21 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-03-25 13:22:32 -0700
commit54f69b92f037f4ff5779e5645ab714dee5b59095 (patch)
treecd935d3d36afbe0627a64c0774b662696c9c06d7 /drivers/misc/dummy-irq.c
parent4c6e22b8a93ef038b70661e590de250a09417af7 (diff)
dummy-irq: introduce a dummy IRQ handler driver
This module accepts a single 'irq' parameter, which it should register for. Its sole purpose is to help with debugging of IRQ sharing problems, by force-enabling IRQ that would otherwise be disabled. Suggested-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Jiri Kosina <jkosina@suse.cz> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/misc/dummy-irq.c')
-rw-r--r--drivers/misc/dummy-irq.c59
1 files changed, 59 insertions, 0 deletions
diff --git a/drivers/misc/dummy-irq.c b/drivers/misc/dummy-irq.c
new file mode 100644
index 00000000000..7014167e2c6
--- /dev/null
+++ b/drivers/misc/dummy-irq.c
@@ -0,0 +1,59 @@
+/*
+ * Dummy IRQ handler driver.
+ *
+ * This module only registers itself as a handler that is specified to it
+ * by the 'irq' parameter.
+ *
+ * The sole purpose of this module is to help with debugging of systems on
+ * which spurious IRQs would happen on disabled IRQ vector.
+ *
+ * Copyright (C) 2013 Jiri Kosina
+ */
+
+/*
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+#include <linux/module.h>
+#include <linux/irq.h>
+#include <linux/interrupt.h>
+
+static int irq;
+
+static irqreturn_t dummy_interrupt(int irq, void *dev_id)
+{
+ static int count = 0;
+
+ if (count == 0) {
+ printk(KERN_INFO "dummy-irq: interrupt occured on IRQ %d\n",
+ irq);
+ count++;
+ }
+
+ return IRQ_NONE;
+}
+
+static int __init dummy_irq_init(void)
+{
+ if (request_irq(irq, &dummy_interrupt, IRQF_SHARED, "dummy_irq", &irq)) {
+ printk(KERN_ERR "dummy-irq: cannot register IRQ %d\n", irq);
+ return -EIO;
+ }
+ printk(KERN_INFO "dummy-irq: registered for IRQ %d\n", irq);
+ return 0;
+}
+
+static void __exit dummy_irq_exit(void)
+{
+ printk(KERN_INFO "dummy-irq unloaded\n");
+ free_irq(irq, &irq);
+}
+
+module_init(dummy_irq_init);
+module_exit(dummy_irq_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Jiri Kosina");
+module_param(irq, uint, 0444);
+MODULE_PARM_DESC(irq, "The IRQ to register for");