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>
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 0635e72..f441726 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -28,6 +28,17 @@
if WATCHDOG
+config WATCHDOG_CORE
+ bool "WatchDog Timer Driver Core"
+ ---help---
+ Say Y here if you want to use the new watchdog timer driver core.
+ This driver provides a framework for all watchdog timer drivers
+ and gives them the /dev/watchdog interface (and later also the
+ sysfs interface).
+
+ To compile this driver as a module, choose M here: the module will
+ be called watchdog.
+
config WATCHDOG_NOWAYOUT
bool "Disable watchdog shutdown on close"
help
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 9eaa212..55bd574 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -2,6 +2,10 @@
# Makefile for the WatchDog device drivers.
#
+# The WatchDog Timer Driver Core.
+watchdog-objs += watchdog_core.o watchdog_dev.o
+obj-$(CONFIG_WATCHDOG_CORE) += watchdog.o
+
# Only one watchdog can succeed. We probe the ISA/PCI/USB based
# watchdog-cards first, then the architecture specific watchdog
# drivers and then the architecture independent "softdog" driver.
diff --git a/drivers/watchdog/watchdog_core.c b/drivers/watchdog/watchdog_core.c
new file mode 100644
index 0000000..47fc126
--- /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");
diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
new file mode 100644
index 0000000..366f49c
--- /dev/null
+++ b/drivers/watchdog/watchdog_dev.c
@@ -0,0 +1,235 @@
+/*
+ * watchdog_dev.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.
+ *
+ * This part of the generic code takes care of the following
+ * misc device: /dev/watchdog.
+ *
+ * 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 module stuff/... */
+#include <linux/types.h> /* For standard types (like size_t) */
+#include <linux/errno.h> /* For the -ENODEV/... values */
+#include <linux/kernel.h> /* For printk/panic/... */
+#include <linux/fs.h> /* For file operations */
+#include <linux/watchdog.h> /* For watchdog specific items */
+#include <linux/miscdevice.h> /* For handling misc devices */
+#include <linux/init.h> /* For __init/__exit/... */
+#include <linux/uaccess.h> /* For copy_to_user/put_user/... */
+
+/* make sure we only register one /dev/watchdog device */
+static unsigned long watchdog_dev_busy;
+/* the watchdog device behind /dev/watchdog */
+static struct watchdog_device *wdd;
+
+/*
+ * watchdog_ping: ping the watchdog.
+ * @wddev: the watchdog device to ping
+ *
+ * If the watchdog has no own ping operation then it needs to be
+ * restarted via the start operation. This wrapper function does
+ * exactly that.
+ */
+
+static int watchdog_ping(struct watchdog_device *wddev)
+{
+ if (wddev->ops->ping)
+ return wddev->ops->ping(wddev); /* ping the watchdog */
+ else
+ return wddev->ops->start(wddev); /* restart the watchdog */
+}
+
+/*
+ * watchdog_write: writes to the watchdog.
+ * @file: file from VFS
+ * @data: user address of data
+ * @len: length of data
+ * @ppos: pointer to the file offset
+ *
+ * A write to a watchdog device is defined as a keepalive ping.
+ */
+
+static ssize_t watchdog_write(struct file *file, const char __user *data,
+ size_t len, loff_t *ppos)
+{
+ size_t i;
+ char c;
+
+ if (len == 0)
+ return 0;
+
+ for (i = 0; i != len; i++) {
+ if (get_user(c, data + i))
+ return -EFAULT;
+ }
+
+ /* someone wrote to us, so we send the watchdog a keepalive ping */
+ watchdog_ping(wdd);
+
+ return len;
+}
+
+/*
+ * watchdog_open: open the /dev/watchdog device.
+ * @inode: inode of device
+ * @file: file handle to device
+ *
+ * When the /dev/watchdog device gets opened, we start the watchdog.
+ * Watch out: the /dev/watchdog device is single open, so we make sure
+ * it can only be opened once.
+ */
+
+static int watchdog_open(struct inode *inode, struct file *file)
+{
+ int err = -EBUSY;
+
+ /* the watchdog is single open! */
+ if (test_and_set_bit(WDOG_DEV_OPEN, &wdd->status))
+ return -EBUSY;
+
+ /*
+ * If the /dev/watchdog device is open, we don't want the module
+ * to be unloaded.
+ */
+ if (!try_module_get(wdd->ops->owner))
+ goto out;
+
+ err = wdd->ops->start(wdd);
+ if (err < 0)
+ goto out_mod;
+
+ /* dev/watchdog is a virtual (and thus non-seekable) filesystem */
+ return nonseekable_open(inode, file);
+
+out_mod:
+ module_put(wdd->ops->owner);
+out:
+ clear_bit(WDOG_DEV_OPEN, &wdd->status);
+ return err;
+}
+
+/*
+ * watchdog_release: release the /dev/watchdog device.
+ * @inode: inode of device
+ * @file: file handle to device
+ *
+ * This is the code for when /dev/watchdog gets closed.
+ */
+
+static int watchdog_release(struct inode *inode, struct file *file)
+{
+ int err;
+
+ err = wdd->ops->stop(wdd);
+ if (err != 0) {
+ pr_crit("%s: watchdog did not stop!\n", wdd->info->identity);
+ watchdog_ping(wdd);
+ }
+
+ /* Allow the owner module to be unloaded again */
+ module_put(wdd->ops->owner);
+
+ /* make sure that /dev/watchdog can be re-opened */
+ clear_bit(WDOG_DEV_OPEN, &wdd->status);
+
+ return 0;
+}
+
+static const struct file_operations watchdog_fops = {
+ .owner = THIS_MODULE,
+ .write = watchdog_write,
+ .open = watchdog_open,
+ .release = watchdog_release,
+};
+
+static struct miscdevice watchdog_miscdev = {
+ .minor = WATCHDOG_MINOR,
+ .name = "watchdog",
+ .fops = &watchdog_fops,
+};
+
+/*
+ * watchdog_dev_register:
+ * @watchdog: watchdog device
+ *
+ * Register a watchdog device as /dev/watchdog. /dev/watchdog
+ * is actually a miscdevice and thus we set it up like that.
+ */
+
+int watchdog_dev_register(struct watchdog_device *watchdog)
+{
+ int err;
+
+ /* Only one device can register for /dev/watchdog */
+ if (test_and_set_bit(0, &watchdog_dev_busy)) {
+ pr_err("only one watchdog can use /dev/watchdog.\n");
+ return -EBUSY;
+ }
+
+ wdd = watchdog;
+
+ err = misc_register(&watchdog_miscdev);
+ if (err != 0) {
+ pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n",
+ watchdog->info->identity, WATCHDOG_MINOR, err);
+ goto out;
+ }
+
+ return 0;
+
+out:
+ wdd = NULL;
+ clear_bit(0, &watchdog_dev_busy);
+ return err;
+}
+
+/*
+ * watchdog_dev_unregister:
+ * @watchdog: watchdog device
+ *
+ * Deregister the /dev/watchdog device.
+ */
+
+int watchdog_dev_unregister(struct watchdog_device *watchdog)
+{
+ /* Check that a watchdog device was registered in the past */
+ if (!test_bit(0, &watchdog_dev_busy) || !wdd)
+ return -ENODEV;
+
+ /* We can only unregister the watchdog device that was registered */
+ if (watchdog != wdd) {
+ pr_err("%s: watchdog was not registered as /dev/watchdog.\n",
+ watchdog->info->identity);
+ return -ENODEV;
+ }
+
+ misc_deregister(&watchdog_miscdev);
+ wdd = NULL;
+ clear_bit(0, &watchdog_dev_busy);
+ return 0;
+}
diff --git a/drivers/watchdog/watchdog_dev.h b/drivers/watchdog/watchdog_dev.h
new file mode 100644
index 0000000..bc7612b
--- /dev/null
+++ b/drivers/watchdog/watchdog_dev.h
@@ -0,0 +1,33 @@
+/*
+ * watchdog_core.h
+ *
+ * (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.
+ */
+
+/*
+ * Functions/procedures to be called by the core
+ */
+int watchdog_dev_register(struct watchdog_device *);
+int watchdog_dev_unregister(struct watchdog_device *);