| /* |
| * 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_set_pretimeout: set the watchdog timer pretimeout |
| * @wddev: the watchdog device to set the timeout for |
| * @timeout: pretimeout to set in seconds |
| */ |
| |
| static int watchdog_set_pretimeout(struct watchdog_device *wddev, |
| unsigned int timeout) |
| { |
| int err; |
| |
| if ((wddev->ops->set_pretimeout == NULL) || |
| !(wddev->info->options & WDIOF_PRETIMEOUT)) |
| return -EOPNOTSUPP; |
| if (watchdog_pretimeout_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_pretimeout(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); |
| case WDIOC_SETPRETIMEOUT: |
| if (get_user(val, p)) |
| return -EFAULT; |
| err = watchdog_set_pretimeout(wdd, val); |
| return err; |
| case WDIOC_GETPRETIMEOUT: |
| return put_user(wdd->pretimeout, 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); |
| } |