watchdog: WatchDog Timer Driver Core - Add basic framework

The WatchDog Timer Driver Core is a framework
that contains the common code for all watchdog-driver's.
It also introduces a watchdog device structure and the
operations that go with it.

This is the introduction of this framework. This part
supports the minimal watchdog userspace API (or with
other words: the functionality to use /dev/watchdog's
open, release and write functionality as defined in
the simplest watchdog API). Extra functionality will
follow in the next set of patches.

Signed-off-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Wolfram Sang <w.sang@pengutronix.de>

1 files changed, 101 insertions, 0 deletions

diff --git a/drivers/watchdog/watchdog_core.c b/drivers/watchdog/watchdog_core.c
new file mode 100644
index 00000000000..47fc1267ad4
--- /dev/null
+++ b/drivers/watchdog/watchdog_core.c
@@ -0,0 +1,101 @@
+/*
+ *	watchdog_core.c
+ *
+ *	(c) Copyright 2008-2011 Alan Cox <alan@lxorguk.ukuu.org.uk>,
+ *						All Rights Reserved.
+ *
+ *	(c) Copyright 2008-2011 Wim Van Sebroeck <wim@iguana.be>.
+ *
+ *	This source code is part of the generic code that can be used
+ *	by all the watchdog timer drivers.
+ *
+ *	Based on source code of the following authors:
+ *	  Matt Domsch <Matt_Domsch@dell.com>,
+ *	  Rob Radez <rob@osinvestor.com>,
+ *	  Rusty Lynch <rusty@linux.co.intel.com>
+ *	  Satyam Sharma <satyam@infradead.org>
+ *	  Randy Dunlap <randy.dunlap@oracle.com>
+ *
+ *	This program is free software; you can redistribute it and/or
+ *	modify it under the terms of the GNU General Public License
+ *	as published by the Free Software Foundation; either version
+ *	2 of the License, or (at your option) any later version.
+ *
+ *	Neither Alan Cox, CymruNet Ltd., Wim Van Sebroeck nor Iguana vzw.
+ *	admit liability nor provide warranty for any of this software.
+ *	This material is provided "AS-IS" and at no charge.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>	/* For EXPORT_SYMBOL/module stuff/... */
+#include <linux/types.h>	/* For standard types */
+#include <linux/errno.h>	/* For the -ENODEV/... values */
+#include <linux/kernel.h>	/* For printk/panic/... */
+#include <linux/watchdog.h>	/* For watchdog specific items */
+#include <linux/init.h>		/* For __init/__exit/... */
+
+#include "watchdog_dev.h"	/* For watchdog_dev_register/... */
+
+/**
+ * watchdog_register_device() - register a watchdog device
+ * @wdd: watchdog device
+ *
+ * Register a watchdog device with the kernel so that the
+ * watchdog timer can be accessed from userspace.
+ *
+ * A zero is returned on success and a negative errno code for
+ * failure.
+ */
+int watchdog_register_device(struct watchdog_device *wdd)
+{
+	int ret;
+
+	if (wdd == NULL || wdd->info == NULL || wdd->ops == NULL)
+		return -EINVAL;
+
+	/* Mandatory operations need to be supported */
+	if (wdd->ops->start == NULL || wdd->ops->stop == NULL)
+		return -EINVAL;
+
+	/*
+	 * Note: now that all watchdog_device data has been verified, we
+	 * will not check this anymore in other functions. If data gets
+	 * corrupted in a later stage then we expect a kernel panic!
+	 */
+
+	/* We only support 1 watchdog device via the /dev/watchdog interface */
+	ret = watchdog_dev_register(wdd);
+	if (ret) {
+		pr_err("error registering /dev/watchdog (err=%d).\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(watchdog_register_device);
+
+/**
+ * watchdog_unregister_device() - unregister a watchdog device
+ * @wdd: watchdog device to unregister
+ *
+ * Unregister a watchdog device that was previously successfully
+ * registered with watchdog_register_device().
+ */
+void watchdog_unregister_device(struct watchdog_device *wdd)
+{
+	int ret;
+
+	if (wdd == NULL)
+		return;
+
+	ret = watchdog_dev_unregister(wdd);
+	if (ret)
+		pr_err("error unregistering /dev/watchdog (err=%d).\n", ret);
+}
+EXPORT_SYMBOL_GPL(watchdog_unregister_device);
+
+MODULE_AUTHOR("Alan Cox <alan@lxorguk.ukuu.org.uk>");
+MODULE_AUTHOR("Wim Van Sebroeck <wim@iguana.be>");
+MODULE_DESCRIPTION("WatchDog Timer Driver Core");
+MODULE_LICENSE("GPL");