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SubjectRe: [PATCH 2/3, RFC] watchdog dev BKL pushdown
Hi Arnd,

> > Actually I'd prefer to fix this for real.  This single open stuff aswell
> > as same set of ioctls are duplicated all over the watchdog drivers.  We'd
> > be much better off introducing a simple watchdog layer that handles this
> > plus proper locking and convert drivers over to it gradually.
>
> I fully agree, I thought the same thing when I did the patches. I remember
> that Wim had a git tree doing this, which is still active at
> http://git.kernel.org/?p=linux/kernel/git/wim/linux-2.6-watchdog-experimental.git;a=commitdiff;h=732c54027e6c866f98857c4a6d1c6c466459dcd5
>
> Unfortunately, it hasn't seen much activitity over the last two years, and
> the number of watchdog drivers seems to have exploded: I count 67 of them,
> including some outside of drivers/watchdog.
>
> Wim, was there anything preventing you from integrating the generic
> watchdog layer back then?

check the linux-2.6-watchdog-mm tree. You'll see the patches sitting there
as the uniform watchdog driver. They are thus also in the -mm tree.
I'll need to change it also to an unlocked_ioctl (and add documentation!)
but I'll attach the core code below (This does not seem to be the latest code,
because I know there was a request to change the alloc_watchdogdev code so that
it could also allocate a private data-area/space).
But it gives you an idea where I was going to. Second step would then be to add
a sysfs interface so that we can start handling mutiple devices.

Greetings,
Wim.

From a223c170e5e7e63e5dd55f56837318db6ad0807f Mon Sep 17 00:00:00 2001
From: Wim Van Sebroeck <wim@iguana.be>
Date: Sun, 19 Aug 2007 19:44:24 +0000
Subject: [PATCH] [WATCHDOG] Uniform Watchdog Device Driver
The Uniform Watchdog Device Driver is a frame-work
that contains the common code for all watchdog-driver's.
It also introduces a watchdog device structure and the
operations that go with it.

Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
---
drivers/watchdog/Kconfig | 2 +
drivers/watchdog/Makefile | 2 +
drivers/watchdog/core/Kconfig | 34 +++
drivers/watchdog/core/Makefile | 11 +
drivers/watchdog/core/watchdog_core.c | 187 +++++++++++++
drivers/watchdog/core/watchdog_dev.c | 463 +++++++++++++++++++++++++++++++++
include/linux/watchdog.h | 49 ++++
7 files changed, 748 insertions(+), 0 deletions(-)
create mode 100644 drivers/watchdog/core/Kconfig
create mode 100644 drivers/watchdog/core/Makefile
create mode 100644 drivers/watchdog/core/watchdog_core.c
create mode 100644 drivers/watchdog/core/watchdog_dev.c
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 37bddc1..a458e87 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -37,6 +37,8 @@ config WATCHDOG_NOWAYOUT
get killed. If you say Y here, the watchdog cannot be stopped once
it has been started.

+source "drivers/watchdog/core/Kconfig"
+
#
# General Watchdog drivers
#
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 389f8b1..b61c103 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -2,6 +2,8 @@
# Makefile for the WatchDog device drivers.
#

+obj-$(CONFIG_WATCHDOG) += core/
+
# Only one watchdog can succeed. We probe the ISA/PCI/USB based
# watchdog-cards first, then the architecture specific watchdog
# drivers and then the architecture independant "softdog" driver.
diff --git a/drivers/watchdog/core/Kconfig b/drivers/watchdog/core/Kconfig
new file mode 100644
index 0000000..a9a23a9
--- /dev/null
+++ b/drivers/watchdog/core/Kconfig
@@ -0,0 +1,34 @@
+#
+# Watchdog device driver core
+#
+
+if WATCHDOG
+
+config WATCHDOG_CORE
+ tristate "Uniform Watchdog Device Driver"
+ depends on EXPERIMENTAL
+ default m
+ ---help---
+ Say Y here if you want to use the new uniform watchdog device
+ driver. This driver provides a framework for all watchdog
+ device drivers and gives them the /dev/watchdog interface (and
+ later also the sysfs interface).
+
+ At this moment we have no watchdog device drivers using this new
+ framework.
+
+ To compile this driver as a module, choose M here: the module will
+ be called watchdog_core.
+
+config WATCHDOG_DEBUG_CORE
+ bool "Uniform Watchdog Device Driver debugging output"
+ depends on WATCHDOG_CORE
+ default n
+ ---help---
+ Say Y here if you want the Uniform Watchdog Device Driver to
+ produce debugging information. Select this if you are having a
+ problem with the uniform watchdog device driver and want to see
+ more of what is really happening.
+
+endif # WATCHDOG
+
diff --git a/drivers/watchdog/core/Makefile b/drivers/watchdog/core/Makefile
new file mode 100644
index 0000000..7554d35
--- /dev/null
+++ b/drivers/watchdog/core/Makefile
@@ -0,0 +1,11 @@
+#
+# Makefile for the Watchdog Device Drivers generic core.
+#
+
+# The Generic Watchdog Driver
+obj-$(CONFIG_WATCHDOG_CORE) += watchdog_core.o watchdog_dev.o
+
diff --git a/drivers/watchdog/core/watchdog_core.c b/drivers/watchdog/core/watchdog_core.c
new file mode 100644
index 0000000..133dc11
--- /dev/null
+++ b/drivers/watchdog/core/watchdog_core.c
@@ -0,0 +1,187 @@
+/*
+ * watchdog.c
+ *
+ * (c) Copyright 2007 Wim Van Sebroeck <wim@iguana.be>.
+ *
+ * This code is generic code that can be shared by all the
+ * watchdog drivers.
+ *
+ * Based on source code of the following authors:
+ * Alan Cox <alan@redhat.com>,
+ * 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 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.
+ */
+
+#include <linux/module.h> /* For module related things/EXPORT_SYMBOL/... */
+#include <linux/types.h> /* For standard types */
+#include <linux/errno.h> /* For the -ENODEV/... values */
+#include <linux/kernel.h> /* For printk/panic/... */
+#include <linux/mm.h> /* For memory allocations ... */
+#include <linux/watchdog.h> /* For watchdog specific items */
+#include <linux/init.h> /* For __init/__exit/... */
+
+/*
+ * Version information
+ */
+#define DRV_VERSION "0.01"
+#define DRV_NAME "watchdog_core"
+#define PFX DRV_NAME ": "
+
+/*
+ * External functions/procedures
+ */
+extern int watchdog_dev_register(struct watchdog_device *, struct device *);
+extern int watchdog_dev_unregister(struct watchdog_device *);
+
+/**
+ * alloc_watchdogdev - allocates a watchdog device
+ *
+ * Creates a new watchdog device structure.
+ * Returns the new structure, or NULL if an error occured.
+ */
+struct watchdog_device *alloc_watchdogdev(void)
+{
+ int alloc_size = sizeof(struct watchdog_device);
+ void *p;
+ struct watchdog_device *dev;
+
+ /* allocate memory for our device and initialize it */
+ p = kzalloc(alloc_size, GFP_KERNEL);
+ if (!p) {
+ printk(KERN_ERR PFX "Unable to allocate watchdog device\n");
+ return NULL;
+ }
+ dev = (struct watchdog_device *) p;
+
+ return dev;
+}
+EXPORT_SYMBOL(alloc_watchdogdev);
+
+/**
+ * free_watchdogdev - free watchdog device
+ * @dev: watchdog device
+ *
+ * This function does the last stage of destroying an allocated
+ * watchdog device.
+ */
+int free_watchdogdev(struct watchdog_device *dev)
+{
+ if (!((dev->watchdog_state == WATCHDOG_UNINITIALIZED) ||
+ (dev->watchdog_state == WATCHDOG_UNREGISTERED))) {
+ printk(KERN_ERR PFX "Unable to destroy a watchdog device that is still in use\n");
+ return -1;
+ }
+
+ kfree(dev);
+ return 0;
+}
+EXPORT_SYMBOL(free_watchdogdev);
+
+/**
+ * register_watchdogdevice - register a watchdog device
+ * @dev: watchdog device
+ * @parent: parent device for the watchdog class device
+ *
+ * This function registers a watchdog device in the kernel so
+ * that it can be accessed from userspace.
+ */
+int register_watchdogdevice(struct watchdog_device *dev, struct device *parent)
+{
+ int ret;
+
+ if (dev == NULL ||
+ dev->watchdog_ops == NULL)
+ return -ENODATA;
+
+ if (dev->watchdog_ops->start == NULL ||
+ dev->watchdog_ops->stop == NULL ||
+ dev->watchdog_ops->keepalive == NULL)
+ return -ENODATA;
+
+ if (!((dev->watchdog_state == WATCHDOG_UNINITIALIZED) ||
+ (dev->watchdog_state == WATCHDOG_UNREGISTERED))) {
+ printk(KERN_ERR PFX "Unable to register a watchdog device that is allready in use\n");
+ return -1;
+ }
+
+ dev->options |= WDIOF_MAGICCLOSE;
+ if (dev->watchdog_ops->set_heartbeat) {
+ dev->options |= WDIOF_SETTIMEOUT;
+ } else {
+ dev->options &= ~WDIOF_SETTIMEOUT;
+ }
+
+ ret = watchdog_dev_register(dev, parent);
+ if (ret) {
+ printk(KERN_ERR PFX "error registering /dev/watchdog (err=%d)",
+ ret);
+ return ret;
+ }
+
+ dev->watchdog_state = WATCHDOG_REGISTERED;
+ return 0;
+}
+EXPORT_SYMBOL(register_watchdogdevice);
+
+/**
+ * unregister_watchdogdevice - unregister a watchdog device
+ * @dev: watchdog device
+ *
+ * This function unregisters a watchdog device from the kernel.
+ */
+int unregister_watchdogdevice(struct watchdog_device *dev)
+{
+ int ret;
+
+ if (dev == NULL)
+ return -ENODATA;
+
+ if ((dev->watchdog_state == WATCHDOG_UNINITIALIZED) ||
+ (dev->watchdog_state == WATCHDOG_UNREGISTERED)) {
+ printk(KERN_ERR PFX "Unable to unregister a watchdog device that has not been registered\n");
+ return -ENODEV;
+ }
+
+ ret = watchdog_dev_unregister(dev);
+ if (ret) {
+ printk(KERN_ERR PFX "error unregistering /dev/watchdog (err=%d)",
+ ret);
+ return ret;
+ }
+
+ dev->watchdog_state = WATCHDOG_UNREGISTERED;
+ return 0;
+}
+EXPORT_SYMBOL(unregister_watchdogdevice);
+
+static int __init watchdog_init(void)
+{
+ printk(KERN_INFO "Uniform watchdog device driver v%s loaded\n",
+ DRV_VERSION);
+ return 0;
+}
+
+static void __exit watchdog_exit(void)
+{
+ printk(KERN_INFO "Uniform watchdog device driver unloaded\n");
+}
+
+module_init(watchdog_init);
+module_exit(watchdog_exit);
+
+MODULE_AUTHOR("Wim Van Sebroeck <wim@iguana.be>");
+MODULE_DESCRIPTION("Uniform Watchdog Device Driver");
+MODULE_VERSION(DRV_VERSION);
+MODULE_LICENSE("GPL");
+MODULE_SUPPORTED_DEVICE("watchdog");
+
diff --git a/drivers/watchdog/core/watchdog_dev.c b/drivers/watchdog/core/watchdog_dev.c
new file mode 100644
index 0000000..37520cd
--- /dev/null
+++ b/drivers/watchdog/core/watchdog_dev.c
@@ -0,0 +1,463 @@
+/*
+ * watchdog_dev.c
+ *
+ * (c) Copyright 2007 Wim Van Sebroeck <wim@iguana.be>.
+ *
+ * This source code is part of the generic code that can be used
+ * by all the watchdog drivers.
+ *
+ * This part of the generic code takes care of the following
+ * misc device: /dev/watchdog.
+ *
+ * Based on source code of the following authors:
+ * Alan Cox <alan@redhat.com>,
+ * 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 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.
+ */
+
+#include <linux/module.h> /* For module related things/EXPORT_SYMBOL/... */
+#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/mutex.h> /* For mutex locking */
+#include <linux/init.h> /* For __init/__exit/... */
+#include <linux/uaccess.h> /* For copy_to_user/put_user/... */
+
+#ifdef CONFIG_WATCHDOG_DEBUG_CORE
+#define trace(format, args...) \
+ printk(KERN_INFO "%s(" format ")\n", __FUNCTION__ , ## args)
+#define dbg(format, arg...) \
+ printk(KERN_DEBUG "%s: " format "\n", __FUNCTION__, ## arg)
+#else
+#define trace(format, arg...) do { } while (0)
+#define dbg(format, arg...) do { } while (0)
+#endif
+
+/*
+ * Version information
+ */
+#define DRV_VERSION "0.01"
+#define DRV_NAME "watchdog_dev"
+#define PFX DRV_NAME ": "
+
+/*
+ * Locally used variables
+ */
+
+static struct watchdog_device *watchdogdev; /* the watchdog device behind /dev/watchdog */
+static unsigned long watchdog_dev_open; /* wether or not /dev/watchdog has been opened */
+static char received_magic_char; /* wether or not we received the magic char */
+static DEFINE_MUTEX(watchdog_register_mtx); /* prevent races between register & unregister */
+
+/*
+ * /dev/watchdog operations
+ */
+
+/*
+ * 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 signal.
+ * Writing the magic 'V' sequence allows the next close to turn
+ * off the watchdog (if 'nowayout' is not set).
+ */
+
+static ssize_t watchdog_write(struct file *file, const char __user *data,
+ size_t len, loff_t *ppos)
+{
+ trace("%p, %p, %zu, %p", file, data, len, ppos);
+
+ if (!watchdogdev ||
+ !watchdogdev->watchdog_ops ||
+ !watchdogdev->watchdog_ops->keepalive)
+ return -ENODEV;
+
+ /* See if we got the magic character 'V' and reload the timer */
+ if (len) {
+ if (!watchdogdev->nowayout) {
+ size_t i;
+
+ /* note: just in case someone wrote the magic character
+ * five months ago... */
+ received_magic_char = 0;
+
+ /* scan to see wether or not we got the magic character */
+ for (i = 0; i != len; i++) {
+ char c;
+ if (get_user(c, data + i))
+ return -EFAULT;
+ if (c == 'V') {
+ received_magic_char = 42;
+ dbg("received the magic character\n");
+ }
+ }
+ }
+
+ /* someone wrote to us, so we sent the watchdog a keepalive signal if
+ * the watchdog is active */
+ if (watchdogdev->watchdog_state == WATCHDOG_STARTED)
+ watchdogdev->watchdog_ops->keepalive(watchdogdev);
+ }
+ return len;
+}
+
+/*
+ * watchdog_ioctl: handle the different ioctl's for the watchdog device.
+ * @inode: inode of the device
+ * @file: file handle to the device
+ * @cmd: watchdog command
+ * @arg: argument pointer
+ *
+ * The watchdog API defines a common set of functions for all watchdogs
+ * according to their available features.
+ */
+
+static int watchdog_ioctl(struct inode *inode, struct file *file,
+ unsigned int cmd, unsigned long arg)
+{
+ int status;
+ int err;
+ int new_options;
+ int new_heartbeat;
+ int time_left;
+ void __user *argp = (void __user *)arg;
+ int __user *p = argp;
+ static struct watchdog_info ident = {
+ .options = 0,
+ .firmware_version = 0,
+ .identity = "Watchdog Device",
+ };
+
+ trace("%p, %p, %u, %li", inode, file, cmd, arg);
+
+ if (!watchdogdev || !watchdogdev->watchdog_ops)
+ return -ENODEV;
+
+ switch (cmd) {
+ case WDIOC_GETSUPPORT:
+ {
+ ident.options = watchdogdev->options;
+ ident.firmware_version = watchdogdev->firmware;
+
+ strncpy(ident.identity, watchdogdev->name, 31);
+ ident.identity[32] = 0;
+
+ return copy_to_user(argp, &ident,
+ sizeof(ident)) ? -EFAULT : 0;
+ }
+
+ case WDIOC_GETSTATUS:
+ {
+ status = 0;
+
+ if (watchdogdev->watchdog_ops->get_status &&
+ watchdogdev->watchdog_ops->get_status(watchdogdev, &status))
+ return -EFAULT;
+
+ return put_user(status, p);
+ }
+
+ case WDIOC_GETBOOTSTATUS:
+ return put_user(watchdogdev->bootstatus, p);
+
+ case WDIOC_KEEPALIVE:
+ {
+ if (!watchdogdev->watchdog_ops->keepalive)
+ return -EFAULT;
+
+ /* We only sent a keepalive when the watchdog is active */
+ if (watchdogdev->watchdog_state == WATCHDOG_STARTED)
+ watchdogdev->watchdog_ops->keepalive(watchdogdev);
+
+ return 0;
+ }
+
+ case WDIOC_SETOPTIONS:
+ {
+ if (get_user(new_options, p))
+ return -EFAULT;
+
+ if (!watchdogdev->watchdog_ops->start ||
+ !watchdogdev->watchdog_ops->stop)
+ return -EFAULT;
+
+ if (new_options & WDIOS_DISABLECARD) {
+ /* only try to stop the watchdog if it's allready running */
+ if (watchdogdev->watchdog_state == WATCHDOG_STARTED) {
+ err = watchdogdev->watchdog_ops->stop(watchdogdev);
+ if (err == 0) {
+ watchdogdev->watchdog_state = WATCHDOG_STOPPED;
+ } else {
+ printk(KERN_CRIT PFX "WDIOS_DISABLECARD not successfull! (err=%d)",
+ err);
+ return -EFAULT;
+ }
+ }
+ }
+
+ if (new_options & WDIOS_ENABLECARD) {
+ /* if the watchdog is not allready running, try to start it */
+ if (watchdogdev->watchdog_state != WATCHDOG_STARTED) {
+ err = watchdogdev->watchdog_ops->start(watchdogdev);
+ if (err == 0) {
+ watchdogdev->watchdog_state = WATCHDOG_STARTED;
+ } else {
+ printk(KERN_CRIT PFX "WDIOS_ENABLECARD not successfull! (err=%d)",
+ err);
+ return -EFAULT;
+ }
+ }
+ }
+
+ return 0;
+ }
+
+ case WDIOC_SETTIMEOUT:
+ {
+ if (!watchdogdev->watchdog_ops->set_heartbeat)
+ return -ENOTTY;
+
+ if (get_user(new_heartbeat, p))
+ return -EFAULT;
+
+ if (watchdogdev->watchdog_ops->set_heartbeat(watchdogdev, new_heartbeat))
+ return -EFAULT;
+
+ /* If the watchdog is active then we sent a keepalive to make sure
+ * that the watchdog keep's running (and if possible takes the new
+ * heartbeat) */
+ if (watchdogdev->watchdog_ops->keepalive &&
+ (watchdogdev->watchdog_state == WATCHDOG_STARTED))
+ watchdogdev->watchdog_ops->keepalive(watchdogdev);
+ /* Fall */
+ }
+
+ case WDIOC_GETTIMEOUT:
+ return put_user(watchdogdev->heartbeat, p);
+
+ case WDIOC_GETTIMELEFT:
+ {
+ if (!watchdogdev->watchdog_ops->get_timeleft)
+ return -ENOTTY;
+
+ if (watchdogdev->watchdog_ops->get_timeleft(watchdogdev, &time_left))
+ return -EFAULT;
+
+ return put_user(time_left, p);
+ }
+
+ default:
+ return -ENOTTY;
+ }
+}
+
+/*
+ * watchdog_open: open the /dev/watchdog device.
+ * @inode: inode of device
+ * @file: file handle to device
+ *
+ * When the /dev/watchdog device get's opened, we start the watchdog
+ * and feed it with his first keepalive signal. Watch out: the
+ * /dev/watchdog device is single open, so make sure it can only be
+ * opened once.
+ */
+
+static int watchdog_open(struct inode *inode, struct file *file)
+{
+ trace("%p, %p", inode, file);
+
+ /* only open if we have a valid watchdog device */
+ if (!watchdogdev ||
+ !watchdogdev->watchdog_ops ||
+ !watchdogdev->watchdog_ops->start ||
+ !watchdogdev->watchdog_ops->stop ||
+ !watchdogdev->watchdog_ops->keepalive)
+ return -EBUSY;
+
+ /* the watchdog is single open! */
+ if (test_and_set_bit(0, &watchdog_dev_open))
+ return -EBUSY;
+
+ /* if the watchdog is not allready running, try to start it */
+ if (watchdogdev->watchdog_state != WATCHDOG_STARTED) {
+ if (watchdogdev->watchdog_ops->start(watchdogdev) == 0)
+ watchdogdev->watchdog_state = WATCHDOG_STARTED;
+ }
+
+ /* if the watchdog started, then feed the watchdog it's first keepalive signal */
+ if (watchdogdev->watchdog_state == WATCHDOG_STARTED)
+ watchdogdev->watchdog_ops->keepalive(watchdogdev);
+
+ return nonseekable_open(inode, file);
+}
+
+/*
+ * watchdog_release: release the /dev/watchdog device.
+ * @inode: inode of device
+ * @file: file handle to device
+ *
+ * This is the code for when /dev/watchdog get's closed. We will only
+ * stop the watchdog when we have received the magic char, else the
+ * watchdog will keep running.
+ */
+
+static int watchdog_release(struct inode *inode, struct file *file)
+{
+ int err;
+
+ trace("%p, %p", inode, file);
+ dbg("received_magic_char=%d", received_magic_char);
+
+ if (watchdogdev && (watchdogdev->watchdog_state == WATCHDOG_STARTED)) {
+ /* Only stop a watchdog if it actually started */
+ if (received_magic_char == 42) {
+ /* we received the magic char -> we can stop the watchdog */
+ if (watchdogdev->watchdog_ops && watchdogdev->watchdog_ops->stop) {
+ err = watchdogdev->watchdog_ops->stop(watchdogdev);
+ if (err == 0) {
+ watchdogdev->watchdog_state = WATCHDOG_STOPPED;
+ } else {
+ printk(KERN_CRIT PFX "Watchdog didn't stop successfull! (err=%d)",
+ err);
+ }
+ } else {
+ printk(KERN_CRIT PFX "Unable to stop watchdog!");
+ }
+ } else {
+ /* If we didn't receive the magic char, then we will close
+ * /dev/watchdog but the watchdog keeps running... */
+ printk(KERN_CRIT PFX "Unexpected close, not stopping watchdog!");
+ if (watchdogdev->watchdog_ops && watchdogdev->watchdog_ops->keepalive) {
+ watchdogdev->watchdog_ops->keepalive(watchdogdev);
+ }
+ }
+ }
+
+ received_magic_char = 0;
+
+ /* make sure that /dev/watchdog can be re-opened */
+ clear_bit(0, &watchdog_dev_open);
+
+ return 0;
+}
+
+/*
+ * /dev/watchdog kernel interfaces
+ */
+
+static struct file_operations watchdog_fops = {
+ .owner = THIS_MODULE,
+ .llseek = no_llseek,
+ .write = watchdog_write,
+ .ioctl = watchdog_ioctl,
+ .open = watchdog_open,
+ .release = watchdog_release,
+};
+
+static struct miscdevice watchdog_miscdev = {
+ .minor = WATCHDOG_MINOR,
+ .name = "watchdog",
+ .fops = &watchdog_fops,
+};
+
+/*
+ * /dev/watchdog register and unregister functions
+ */
+
+/*
+ * watchdog_dev_register:
+ *
+ * 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 *wdd, struct device *parent)
+{
+ int err = -EBUSY;
+
+ trace("%p %p", wdd, parent);
+
+ mutex_lock(&watchdog_register_mtx);
+
+ if (watchdogdev) {
+ printk(KERN_ERR PFX "another watchdog device is allready registered as /dev/watchdog\n");
+ goto out;
+ }
+
+ watchdog_miscdev.parent = parent;
+
+ dbg("Register a new /dev/watchdog device\n");
+ err = misc_register(&watchdog_miscdev);
+ if (err != 0) {
+ printk(KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n",
+ watchdog_miscdev.minor, err);
+ goto out;
+ }
+
+ watchdogdev = wdd;
+
+out:
+ mutex_unlock(&watchdog_register_mtx);
+ return err;
+}
+EXPORT_SYMBOL(watchdog_dev_register);
+
+/*
+ * watchdog_dev_unregister:
+ *
+ * Deregister the /dev/watchdog device.
+ */
+
+int watchdog_dev_unregister(struct watchdog_device *wdd)
+{
+ trace("%p", wdd);
+
+ mutex_lock(&watchdog_register_mtx);
+
+ if (!watchdogdev) {
+ printk(KERN_ERR PFX "there is no watchdog registered\n");
+ mutex_unlock(&watchdog_register_mtx);
+ return -1;
+ }
+
+ if (!wdd) {
+ printk(KERN_ERR PFX "cannot unregister non-existing watchdog-driver\n");
+ mutex_unlock(&watchdog_register_mtx);
+ return -2;
+ }
+
+ if (watchdogdev != wdd) {
+ printk(KERN_ERR PFX "another watchdog device is running\n");
+ mutex_unlock(&watchdog_register_mtx);
+ return -3;
+ }
+
+ dbg("Unregister /dev/watchdog device\n");
+ misc_deregister(&watchdog_miscdev);
+ watchdogdev = NULL;
+ mutex_unlock(&watchdog_register_mtx);
+ return 0;
+}
+EXPORT_SYMBOL(watchdog_dev_unregister);
+
+MODULE_AUTHOR("Wim Van Sebroeck <wim@iguana.be>");
+MODULE_DESCRIPTION("Generic /dev/watchdog Code");
+MODULE_VERSION(DRV_VERSION);
+MODULE_LICENSE("GPL");
+
diff --git a/include/linux/watchdog.h b/include/linux/watchdog.h
index 011bcfe..4f57bf4 100644
--- a/include/linux/watchdog.h
+++ b/include/linux/watchdog.h
@@ -53,12 +53,61 @@ struct watchdog_info {

#ifdef __KERNEL__

+#include <linux/device.h>
+
#ifdef CONFIG_WATCHDOG_NOWAYOUT
#define WATCHDOG_NOWAYOUT 1
#else
#define WATCHDOG_NOWAYOUT 0
#endif

+struct watchdog_ops;
+struct watchdog_device;
+
+struct watchdog_ops {
+ /* mandatory routines */
+ /* operation = start watchdog */
+ int (*start)(struct watchdog_device *);
+ /* operation = stop watchdog */
+ int (*stop)(struct watchdog_device *);
+ /* operation = send keepalive ping */
+ int (*keepalive)(struct watchdog_device *);
+ /* optional routines */
+ /* operation = set watchdog's heartbeat */
+ int (*set_heartbeat)(struct watchdog_device *, int);
+ /* operation = get the watchdog's status */
+ int (*get_status)(struct watchdog_device *, int *);
+ /* operation = get the time left before reboot */
+ int (*get_timeleft)(struct watchdog_device *, int *);
+};
+
+struct watchdog_device {
+ unsigned char name[32]; /* The watchdog's 'identity' */
+ unsigned long options; /* The supported capabilities/options */
+ unsigned long firmware; /* The Watchdog's Firmware version */
+ int nowayout; /* The nowayout setting for this watchdog */
+ int heartbeat; /* The watchdog's heartbeat */
+ int bootstatus; /* The watchdog's bootstatus */
+ struct watchdog_ops *watchdog_ops; /* link to watchdog_ops */
+
+ /* watchdog status (register/unregister) state machine */
+ enum { WATCHDOG_UNINITIALIZED = 0,
+ WATCHDOG_REGISTERED, /* completed register_watchdogdevice */
+ WATCHDOG_STARTED, /* watchdog device started */
+ WATCHDOG_STOPPED, /* watchdog device stopped */
+ WATCHDOG_UNREGISTERED, /* completed unregister_watchdogdevice */
+ } watchdog_state;
+
+ /* From here on everything is device dependent */
+ void *private;
+};
+
+/* drivers/watchdog/watchdog_core.c */
+extern struct watchdog_device *alloc_watchdogdev(void);
+extern int register_watchdogdevice(struct watchdog_device *, struct device *);
+extern int unregister_watchdogdevice(struct watchdog_device *);
+extern int free_watchdogdev(struct watchdog_device *);
+
#endif /* __KERNEL__ */

#endif /* ifndef _LINUX_WATCHDOG_H */
--
1.5.3.4
--
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