--- /dev/null
+/*
+ * 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/... */
+
+#include "watchdog_core.h"
+
+/* the dev_t structure to store the dynamically allocated watchdog devices */
+static dev_t watchdog_devt;
+/* the watchdog device behind /dev/watchdog */
+static struct watchdog_device *old_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.
+ * We only ping when the watchdog device is running.
+ */
+
+static int watchdog_ping(struct watchdog_device *wddev)
+{
+ int err = 0;
+
+ mutex_lock(&wddev->lock);
+
+ if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
+ err = -ENODEV;
+ goto out_ping;
+ }
+
+ if (!watchdog_active(wddev))
+ goto out_ping;
+
+ if (wddev->ops->ping)
+ err = wddev->ops->ping(wddev); /* ping the watchdog */
+ else
+ err = wddev->ops->start(wddev); /* restart watchdog */
+
+out_ping:
+ mutex_unlock(&wddev->lock);
+ return err;
+}
+
+/*
+ * watchdog_start: wrapper to start the watchdog.
+ * @wddev: the watchdog device to start
+ *
+ * Start the watchdog if it is not active and mark it active.
+ * This function returns zero on success or a negative errno code for
+ * failure.
+ */
+
+static int watchdog_start(struct watchdog_device *wddev)
+{
+ int err = 0;
+
+ mutex_lock(&wddev->lock);
+
+ if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
+ err = -ENODEV;
+ goto out_start;
+ }
+
+ if (watchdog_active(wddev))
+ goto out_start;
+
+ err = wddev->ops->start(wddev);
+ if (err == 0)
+ set_bit(WDOG_ACTIVE, &wddev->status);
+
+out_start:
+ mutex_unlock(&wddev->lock);
+ return err;
+}
+
+/*
+ * watchdog_stop: wrapper to stop the watchdog.
+ * @wddev: the watchdog device to stop
+ *
+ * Stop the watchdog if it is still active and unmark it active.
+ * This function returns zero on success or a negative errno code for
+ * failure.
+ * If the 'nowayout' feature was set, the watchdog cannot be stopped.
+ */
+
+static int watchdog_stop(struct watchdog_device *wddev)
+{
+ int err = 0;
+
+ mutex_lock(&wddev->lock);
+
+ if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
+ err = -ENODEV;
+ goto out_stop;
+ }
+
+ if (!watchdog_active(wddev))
+ goto out_stop;
+
+ if (test_bit(WDOG_NO_WAY_OUT, &wddev->status)) {
+ dev_info(wddev->dev, "nowayout prevents watchdog being stopped!\n");
+ err = -EBUSY;
+ goto out_stop;
+ }
+
+ err = wddev->ops->stop(wddev);
+ if (err == 0)
+ clear_bit(WDOG_ACTIVE, &wddev->status);
+
+out_stop:
+ mutex_unlock(&wddev->lock);
+ return err;
+}
+
+/*
+ * watchdog_get_status: wrapper to get the watchdog status
+ * @wddev: the watchdog device to get the status from
+ * @status: the status of the watchdog device
+ *
+ * Get the watchdog's status flags.
+ */
+
+static int watchdog_get_status(struct watchdog_device *wddev,
+ unsigned int *status)
+{
+ int err = 0;
+
+ *status = 0;
+ if (!wddev->ops->status)
+ return -EOPNOTSUPP;
+
+ mutex_lock(&wddev->lock);
+
+ if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
+ err = -ENODEV;
+ goto out_status;
+ }
+
+ *status = wddev->ops->status(wddev);
+
+out_status:
+ mutex_unlock(&wddev->lock);
+ return err;
+}
+
+/*
+ * watchdog_set_timeout: set the watchdog timer timeout
+ * @wddev: the watchdog device to set the timeout for
+ * @timeout: timeout to set in seconds
+ */
+
+static int watchdog_set_timeout(struct watchdog_device *wddev,
+ unsigned int timeout)
+{
+ int err;
+
+ if ((wddev->ops->set_timeout == NULL) ||
+ !(wddev->info->options & WDIOF_SETTIMEOUT))
+ return -EOPNOTSUPP;
+
+ if (watchdog_timeout_invalid(wddev, timeout))
+ return -EINVAL;
+
+ mutex_lock(&wddev->lock);
+
+ if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
+ err = -ENODEV;
+ goto out_timeout;
+ }
+
+ err = wddev->ops->set_timeout(wddev, timeout);
+
+out_timeout:
+ mutex_unlock(&wddev->lock);
+ return err;
+}
+
+/*
+ * watchdog_get_timeleft: wrapper to get the time left before a reboot
+ * @wddev: the watchdog device to get the remaining time from
+ * @timeleft: the time that's left
+ *
+ * Get the time before a watchdog will reboot (if not pinged).
+ */
+
+static int watchdog_get_timeleft(struct watchdog_device *wddev,
+ unsigned int *timeleft)
+{
+ int err = 0;
+
+ *timeleft = 0;
+ if (!wddev->ops->get_timeleft)
+ return -EOPNOTSUPP;
+
+ mutex_lock(&wddev->lock);
+
+ if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
+ err = -ENODEV;
+ goto out_timeleft;
+ }
+
+ *timeleft = wddev->ops->get_timeleft(wddev);
+
+out_timeleft:
+ mutex_unlock(&wddev->lock);
+ return err;
+}
+
+/*
+ * watchdog_ioctl_op: call the watchdog drivers ioctl op if defined
+ * @wddev: the watchdog device to do the ioctl on
+ * @cmd: watchdog command
+ * @arg: argument pointer
+ */
+
+static int watchdog_ioctl_op(struct watchdog_device *wddev, unsigned int cmd,
+ unsigned long arg)
+{
+ int err;
+
+ if (!wddev->ops->ioctl)
+ return -ENOIOCTLCMD;
+
+ mutex_lock(&wddev->lock);
+
+ if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
+ err = -ENODEV;
+ goto out_ioctl;
+ }
+
+ err = wddev->ops->ioctl(wddev, cmd, arg);
+
+out_ioctl:
+ mutex_unlock(&wddev->lock);
+ return err;
+}
+
+/*
+ * 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.
+ * 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)
+{
+ struct watchdog_device *wdd = file->private_data;
+ size_t i;
+ char c;
+
+ if (len == 0)
+ return 0;
+
+ /*
+ * Note: just in case someone wrote the magic character
+ * five months ago...
+ */
+ clear_bit(WDOG_ALLOW_RELEASE, &wdd->status);
+
+ /* scan to see whether or not we got the magic character */
+ for (i = 0; i != len; i++) {
+ if (get_user(c, data + i))
+ return -EFAULT;
+ if (c == 'V')
+ set_bit(WDOG_ALLOW_RELEASE, &wdd->status);
+ }
+
+ /* someone wrote to us, so we send the watchdog a keepalive ping */
+ watchdog_ping(wdd);
+
+ return len;
+}
+
+/*
+ * watchdog_ioctl: handle the different ioctl's for the watchdog 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 long watchdog_ioctl(struct file *file, unsigned int cmd,
+ unsigned long arg)
+{
+ struct watchdog_device *wdd = file->private_data;
+ void __user *argp = (void __user *)arg;
+ int __user *p = argp;
+ unsigned int val;
+ int err;
+
+ err = watchdog_ioctl_op(wdd, cmd, arg);
+ if (err != -ENOIOCTLCMD)
+ return err;
+
+ switch (cmd) {
+ case WDIOC_GETSUPPORT:
+ return copy_to_user(argp, wdd->info,
+ sizeof(struct watchdog_info)) ? -EFAULT : 0;
+ case WDIOC_GETSTATUS:
+ err = watchdog_get_status(wdd, &val);
+ if (err == -ENODEV)
+ return err;
+ return put_user(val, p);
+ case WDIOC_GETBOOTSTATUS:
+ return put_user(wdd->bootstatus, p);
+ case WDIOC_SETOPTIONS:
+ if (get_user(val, p))
+ return -EFAULT;
+ if (val & WDIOS_DISABLECARD) {
+ err = watchdog_stop(wdd);
+ if (err < 0)
+ return err;
+ }
+ if (val & WDIOS_ENABLECARD) {
+ err = watchdog_start(wdd);
+ if (err < 0)
+ return err;
+ }
+ return 0;
+ case WDIOC_KEEPALIVE:
+ if (!(wdd->info->options & WDIOF_KEEPALIVEPING))
+ return -EOPNOTSUPP;
+ watchdog_ping(wdd);
+ return 0;
+ case WDIOC_SETTIMEOUT:
+ if (get_user(val, p))
+ return -EFAULT;
+ err = watchdog_set_timeout(wdd, val);
+ if (err < 0)
+ return err;
+ /* If the watchdog is active then we send a keepalive ping
+ * to make sure that the watchdog keep's running (and if
+ * possible that it takes the new timeout) */
+ watchdog_ping(wdd);
+ /* Fall */
+ case WDIOC_GETTIMEOUT:
+ /* timeout == 0 means that we don't know the timeout */
+ if (wdd->timeout == 0)
+ return -EOPNOTSUPP;
+ return put_user(wdd->timeout, p);
+ case WDIOC_GETTIMELEFT:
+ err = watchdog_get_timeleft(wdd, &val);
+ if (err)
+ return err;
+ return put_user(val, p);
+ default:
+ return -ENOTTY;
+ }
+}
+
+/*
+ * watchdog_open: open the /dev/watchdog* devices.
+ * @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;
+ struct watchdog_device *wdd;
+
+ /* Get the corresponding watchdog device */
+ if (imajor(inode) == MISC_MAJOR)
+ wdd = old_wdd;
+ else
+ wdd = container_of(inode->i_cdev, struct watchdog_device, cdev);
+
+ /* 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 = watchdog_start(wdd);
+ if (err < 0)
+ goto out_mod;
+
+ file->private_data = wdd;
+
+ if (wdd->ops->ref)
+ wdd->ops->ref(wdd);
+
+ /* 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 watchdog device.
+ * @inode: inode of device
+ * @file: file handle to device
+ *
+ * This is the code for when /dev/watchdog gets closed. We will only
+ * stop the watchdog when we have received the magic char (and nowayout
+ * was not set), else the watchdog will keep running.
+ */
+
+static int watchdog_release(struct inode *inode, struct file *file)
+{
+ struct watchdog_device *wdd = file->private_data;
+ int err = -EBUSY;
+
+ /*
+ * We only stop the watchdog if we received the magic character
+ * or if WDIOF_MAGICCLOSE is not set. If nowayout was set then
+ * watchdog_stop will fail.
+ */
+ if (!test_bit(WDOG_ACTIVE, &wdd->status))
+ err = 0;
+ else if (test_and_clear_bit(WDOG_ALLOW_RELEASE, &wdd->status) ||
+ !(wdd->info->options & WDIOF_MAGICCLOSE))
+ err = watchdog_stop(wdd);
+
+ /* If the watchdog was not stopped, send a keepalive ping */
+ if (err < 0) {
+ mutex_lock(&wdd->lock);
+ if (!test_bit(WDOG_UNREGISTERED, &wdd->status))
+ dev_crit(wdd->dev, "watchdog did not stop!\n");
+ mutex_unlock(&wdd->lock);
+ 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);
+
+ /* Note wdd may be gone after this, do not use after this! */
+ if (wdd->ops->unref)
+ wdd->ops->unref(wdd);
+
+ return 0;
+}
+
+static const struct file_operations watchdog_fops = {
+ .owner = THIS_MODULE,
+ .write = watchdog_write,
+ .unlocked_ioctl = watchdog_ioctl,
+ .open = watchdog_open,
+ .release = watchdog_release,
+};
+
+static struct miscdevice watchdog_miscdev = {
+ .minor = WATCHDOG_MINOR,
+ .name = "watchdog",
+ .fops = &watchdog_fops,
+};
+
+/*
+ * watchdog_dev_register: register a watchdog device
+ * @watchdog: watchdog device
+ *
+ * Register a watchdog device including handling the legacy
+ * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
+ * thus we set it up like that.
+ */
+
+int watchdog_dev_register(struct watchdog_device *watchdog)
+{
+ int err, devno;
+
+ if (watchdog->id == 0) {
+ old_wdd = watchdog;
+ watchdog_miscdev.parent = watchdog->parent;
+ 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);
+ if (err == -EBUSY)
+ pr_err("%s: a legacy watchdog module is probably present.\n",
+ watchdog->info->identity);
+ old_wdd = NULL;
+ return err;
+ }
+ }
+
+ /* Fill in the data structures */
+ devno = MKDEV(MAJOR(watchdog_devt), watchdog->id);
+ cdev_init(&watchdog->cdev, &watchdog_fops);
+ watchdog->cdev.owner = watchdog->ops->owner;
+
+ /* Add the device */
+ err = cdev_add(&watchdog->cdev, devno, 1);
+ if (err) {
+ pr_err("watchdog%d unable to add device %d:%d\n",
+ watchdog->id, MAJOR(watchdog_devt), watchdog->id);
+ if (watchdog->id == 0) {
+ misc_deregister(&watchdog_miscdev);
+ old_wdd = NULL;
+ }
+ }
+ return err;
+}
+
+/*
+ * watchdog_dev_unregister: unregister a watchdog device
+ * @watchdog: watchdog device
+ *
+ * Unregister the watchdog and if needed the legacy /dev/watchdog device.
+ */
+
+int watchdog_dev_unregister(struct watchdog_device *watchdog)
+{
+ mutex_lock(&watchdog->lock);
+ set_bit(WDOG_UNREGISTERED, &watchdog->status);
+ mutex_unlock(&watchdog->lock);
+
+ cdev_del(&watchdog->cdev);
+ if (watchdog->id == 0) {
+ misc_deregister(&watchdog_miscdev);
+ old_wdd = NULL;
+ }
+ return 0;
+}
+
+/*
+ * watchdog_dev_init: init dev part of watchdog core
+ *
+ * Allocate a range of chardev nodes to use for watchdog devices
+ */
+
+int __init watchdog_dev_init(void)
+{
+ int err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog");
+ if (err < 0)
+ pr_err("watchdog: unable to allocate char dev region\n");
+ return err;
+}
+
+/*
+ * watchdog_dev_exit: exit dev part of watchdog core
+ *
+ * Release the range of chardev nodes used for watchdog devices
+ */
+
+void __exit watchdog_dev_exit(void)
+{
+ unregister_chrdev_region(watchdog_devt, MAX_DOGS);
+}
Code Review / kvmfornfv.git / blobdiff