/* * watchdog_dev.c * * (c) Copyright 2008-2011 Alan Cox , * All Rights Reserved. * * (c) Copyright 2008-2011 Wim Van Sebroeck . * * * 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 , * Rob Radez , * Rusty Lynch * Satyam Sharma * Randy Dunlap * * 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 /* For character device */ #include /* For the -ENODEV/... values */ #include /* For file operations */ #include /* For __init/__exit/... */ #include /* For printk/panic/... */ #include /* For data references */ #include /* For handling misc devices */ #include /* For module stuff/... */ #include /* For mutexes */ #include /* For memory functions */ #include /* For standard types (like size_t) */ #include /* For watchdog specific items */ #include /* For copy_to_user/put_user/... */ #include "watchdog_core.h" /* * struct watchdog_core_data - watchdog core internal data * @kref: Reference count. * @cdev: The watchdog's Character device. * @wdd: Pointer to watchdog device. * @lock: Lock for watchdog core. * @status: Watchdog core internal status bits. */ struct watchdog_core_data { struct kref kref; struct cdev cdev; struct watchdog_device *wdd; struct mutex lock; unsigned long status; /* Internal status bits */ #define _WDOG_DEV_OPEN 0 /* Opened ? */ #define _WDOG_ALLOW_RELEASE 1 /* Did we receive the magic char ? */ }; /* the dev_t structure to store the dynamically allocated watchdog devices */ static dev_t watchdog_devt; /* Reference to watchdog device behind /dev/watchdog */ static struct watchdog_core_data *old_wd_data; /* * watchdog_ping: ping the watchdog. * @wdd: the watchdog device to ping * * The caller must hold wd_data->lock. * * 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 *wdd) { int err; if (!watchdog_active(wdd)) return 0; if (wdd->ops->ping) err = wdd->ops->ping(wdd); /* ping the watchdog */ else err = wdd->ops->start(wdd); /* restart watchdog */ return err; } /* * watchdog_start: wrapper to start the watchdog. * @wdd: the watchdog device to start * * The caller must hold wd_data->lock. * * 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 *wdd) { int err; if (watchdog_active(wdd)) return 0; err = wdd->ops->start(wdd); if (err == 0) set_bit(WDOG_ACTIVE, &wdd->status); return err; } /* * watchdog_stop: wrapper to stop the watchdog. * @wdd: the watchdog device to stop * * The caller must hold wd_data->lock. * * 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 *wdd) { int err; if (!watchdog_active(wdd)) return 0; if (test_bit(WDOG_NO_WAY_OUT, &wdd->status)) { dev_info(wdd->dev, "nowayout prevents watchdog being stopped!\n"); return -EBUSY; } err = wdd->ops->stop(wdd); if (err == 0) clear_bit(WDOG_ACTIVE, &wdd->status); return err; } /* * watchdog_get_status: wrapper to get the watchdog status * @wdd: the watchdog device to get the status from * * The caller must hold wd_data->lock. * * Get the watchdog's status flags. */ static unsigned int watchdog_get_status(struct watchdog_device *wdd) { if (!wdd->ops->status) return 0; return wdd->ops->status(wdd); } /* * watchdog_set_timeout: set the watchdog timer timeout * @wdd: the watchdog device to set the timeout for * @timeout: timeout to set in seconds * * The caller must hold wd_data->lock. */ static int watchdog_set_timeout(struct watchdog_device *wdd, unsigned int timeout) { if (!wdd->ops->set_timeout || !(wdd->info->options & WDIOF_SETTIMEOUT)) return -EOPNOTSUPP; if (watchdog_timeout_invalid(wdd, timeout)) return -EINVAL; return wdd->ops->set_timeout(wdd, timeout); } /* * watchdog_get_timeleft: wrapper to get the time left before a reboot * @wdd: the watchdog device to get the remaining time from * @timeleft: the time that's left * * The caller must hold wd_data->lock. * * Get the time before a watchdog will reboot (if not pinged). */ static int watchdog_get_timeleft(struct watchdog_device *wdd, unsigned int *timeleft) { *timeleft = 0; if (!wdd->ops->get_timeleft) return -EOPNOTSUPP; *timeleft = wdd->ops->get_timeleft(wdd); return 0; } #ifdef CONFIG_WATCHDOG_SYSFS static ssize_t nowayout_show(struct device *dev, struct device_attribute *attr, char *buf) { struct watchdog_device *wdd = dev_get_drvdata(dev); return sprintf(buf, "%d\n", !!test_bit(WDOG_NO_WAY_OUT, &wdd->status)); } static DEVICE_ATTR_RO(nowayout); static ssize_t status_show(struct device *dev, struct device_attribute *attr, char *buf) { struct watchdog_device *wdd = dev_get_drvdata(dev); struct watchdog_core_data *wd_data = wdd->wd_data; unsigned int status; mutex_lock(&wd_data->lock); status = watchdog_get_status(wdd); mutex_unlock(&wd_data->lock); return sprintf(buf, "%u\n", status); } static DEVICE_ATTR_RO(status); static ssize_t bootstatus_show(struct device *dev, struct device_attribute *attr, char *buf) { struct watchdog_device *wdd = dev_get_drvdata(dev); return sprintf(buf, "%u\n", wdd->bootstatus); } static DEVICE_ATTR_RO(bootstatus); static ssize_t timeleft_show(struct device *dev, struct device_attribute *attr, char *buf) { struct watchdog_device *wdd = dev_get_drvdata(dev); struct watchdog_core_data *wd_data = wdd->wd_data; ssize_t status; unsigned int val; mutex_lock(&wd_data->lock); status = watchdog_get_timeleft(wdd, &val); mutex_unlock(&wd_data->lock); if (!status) status = sprintf(buf, "%u\n", val); return status; } static DEVICE_ATTR_RO(timeleft); static ssize_t timeout_show(struct device *dev, struct device_attribute *attr, char *buf) { struct watchdog_device *wdd = dev_get_drvdata(dev); return sprintf(buf, "%u\n", wdd->timeout); } static DEVICE_ATTR_RO(timeout); static ssize_t identity_show(struct device *dev, struct device_attribute *attr, char *buf) { struct watchdog_device *wdd = dev_get_drvdata(dev); return sprintf(buf, "%s\n", wdd->info->identity); } static DEVICE_ATTR_RO(identity); static ssize_t state_show(struct device *dev, struct device_attribute *attr, char *buf) { struct watchdog_device *wdd = dev_get_drvdata(dev); if (watchdog_active(wdd)) return sprintf(buf, "active\n"); return sprintf(buf, "inactive\n"); } static DEVICE_ATTR_RO(state); static umode_t wdt_is_visible(struct kobject *kobj, struct attribute *attr, int n) { struct device *dev = container_of(kobj, struct device, kobj); struct watchdog_device *wdd = dev_get_drvdata(dev); umode_t mode = attr->mode; if (attr == &dev_attr_status.attr && !wdd->ops->status) mode = 0; else if (attr == &dev_attr_timeleft.attr && !wdd->ops->get_timeleft) mode = 0; return mode; } static struct attribute *wdt_attrs[] = { &dev_attr_state.attr, &dev_attr_identity.attr, &dev_attr_timeout.attr, &dev_attr_timeleft.attr, &dev_attr_bootstatus.attr, &dev_attr_status.attr, &dev_attr_nowayout.attr, NULL, }; static const struct attribute_group wdt_group = { .attrs = wdt_attrs, .is_visible = wdt_is_visible, }; __ATTRIBUTE_GROUPS(wdt); #else #define wdt_groups NULL #endif /* * watchdog_ioctl_op: call the watchdog drivers ioctl op if defined * @wdd: the watchdog device to do the ioctl on * @cmd: watchdog command * @arg: argument pointer * * The caller must hold wd_data->lock. */ static int watchdog_ioctl_op(struct watchdog_device *wdd, unsigned int cmd, unsigned long arg) { if (!wdd->ops->ioctl) return -ENOIOCTLCMD; return wdd->ops->ioctl(wdd, cmd, arg); } /* * 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_core_data *wd_data = file->private_data; struct watchdog_device *wdd; int err; 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, &wd_data->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, &wd_data->status); } /* someone wrote to us, so we send the watchdog a keepalive ping */ err = -ENODEV; mutex_lock(&wd_data->lock); wdd = wd_data->wdd; if (wdd) err = watchdog_ping(wdd); mutex_unlock(&wd_data->lock); if (err < 0) return err; 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_core_data *wd_data = file->private_data; void __user *argp = (void __user *)arg; struct watchdog_device *wdd; int __user *p = argp; unsigned int val; int err; mutex_lock(&wd_data->lock); wdd = wd_data->wdd; if (!wdd) { err = -ENODEV; goto out_ioctl; } err = watchdog_ioctl_op(wdd, cmd, arg); if (err != -ENOIOCTLCMD) goto out_ioctl; switch (cmd) { case WDIOC_GETSUPPORT: err = copy_to_user(argp, wdd->info, sizeof(struct watchdog_info)) ? -EFAULT : 0; break; case WDIOC_GETSTATUS: val = watchdog_get_status(wdd); err = put_user(val, p); break; case WDIOC_GETBOOTSTATUS: err = put_user(wdd->bootstatus, p); break; case WDIOC_SETOPTIONS: if (get_user(val, p)) { err = -EFAULT; break; } if (val & WDIOS_DISABLECARD) { err = watchdog_stop(wdd); if (err < 0) break; } if (val & WDIOS_ENABLECARD) err = watchdog_start(wdd); break; case WDIOC_KEEPALIVE: if (!(wdd->info->options & WDIOF_KEEPALIVEPING)) { err = -EOPNOTSUPP; break; } err = watchdog_ping(wdd); break; case WDIOC_SETTIMEOUT: if (get_user(val, p)) { err = -EFAULT; break; } err = watchdog_set_timeout(wdd, val); if (err < 0) break; /* 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) */ err = watchdog_ping(wdd); if (err < 0) break; /* Fall */ case WDIOC_GETTIMEOUT: /* timeout == 0 means that we don't know the timeout */ if (wdd->timeout == 0) { err = -EOPNOTSUPP; break; } err = put_user(wdd->timeout, p); break; case WDIOC_GETTIMELEFT: err = watchdog_get_timeleft(wdd, &val); if (err < 0) break; err = put_user(val, p); break; default: err = -ENOTTY; break; } out_ioctl: mutex_unlock(&wd_data->lock); return err; } /* * 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) { struct watchdog_core_data *wd_data; struct watchdog_device *wdd; int err; /* Get the corresponding watchdog device */ if (imajor(inode) == MISC_MAJOR) wd_data = old_wd_data; else wd_data = container_of(inode->i_cdev, struct watchdog_core_data, cdev); /* the watchdog is single open! */ if (test_and_set_bit(_WDOG_DEV_OPEN, &wd_data->status)) return -EBUSY; wdd = wd_data->wdd; /* * If the /dev/watchdog device is open, we don't want the module * to be unloaded. */ if (!try_module_get(wdd->ops->owner)) { err = -EBUSY; goto out_clear; } err = watchdog_start(wdd); if (err < 0) goto out_mod; file->private_data = wd_data; kref_get(&wd_data->kref); /* dev/watchdog is a virtual (and thus non-seekable) filesystem */ return nonseekable_open(inode, file); out_mod: module_put(wd_data->wdd->ops->owner); out_clear: clear_bit(_WDOG_DEV_OPEN, &wd_data->status); return err; } static void watchdog_core_data_release(struct kref *kref) { struct watchdog_core_data *wd_data; wd_data = container_of(kref, struct watchdog_core_data, kref); kfree(wd_data); } /* * 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_core_data *wd_data = file->private_data; struct watchdog_device *wdd; int err = -EBUSY; mutex_lock(&wd_data->lock); wdd = wd_data->wdd; if (!wdd) goto done; /* * 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, &wd_data->status) || !(wdd->info->options & WDIOF_MAGICCLOSE)) err = watchdog_stop(wdd); /* If the watchdog was not stopped, send a keepalive ping */ if (err < 0) { dev_crit(wdd->dev, "watchdog did not stop!\n"); watchdog_ping(wdd); } /* make sure that /dev/watchdog can be re-opened */ clear_bit(_WDOG_DEV_OPEN, &wd_data->status); done: mutex_unlock(&wd_data->lock); /* Allow the owner module to be unloaded again */ module_put(wd_data->cdev.owner); kref_put(&wd_data->kref, watchdog_core_data_release); 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_cdev_register: register watchdog character device * @wdd: watchdog device * @devno: character device number * * Register a watchdog character device including handling the legacy * /dev/watchdog node. /dev/watchdog is actually a miscdevice and * thus we set it up like that. */ static int watchdog_cdev_register(struct watchdog_device *wdd, dev_t devno) { struct watchdog_core_data *wd_data; int err; wd_data = kzalloc(sizeof(struct watchdog_core_data), GFP_KERNEL); if (!wd_data) return -ENOMEM; kref_init(&wd_data->kref); mutex_init(&wd_data->lock); wd_data->wdd = wdd; wdd->wd_data = wd_data; if (wdd->id == 0) { old_wd_data = wd_data; watchdog_miscdev.parent = wdd->parent; err = misc_register(&watchdog_miscdev); if (err != 0) { pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n", wdd->info->identity, WATCHDOG_MINOR, err); if (err == -EBUSY) pr_err("%s: a legacy watchdog module is probably present.\n", wdd->info->identity); old_wd_data = NULL; kfree(wd_data); return err; } } /* Fill in the data structures */ cdev_init(&wd_data->cdev, &watchdog_fops); wd_data->cdev.owner = wdd->ops->owner; /* Add the device */ err = cdev_add(&wd_data->cdev, devno, 1); if (err) { pr_err("watchdog%d unable to add device %d:%d\n", wdd->id, MAJOR(watchdog_devt), wdd->id); if (wdd->id == 0) { misc_deregister(&watchdog_miscdev); old_wd_data = NULL; kref_put(&wd_data->kref, watchdog_core_data_release); } } return err; } /* * watchdog_cdev_unregister: unregister watchdog character device * @watchdog: watchdog device * * Unregister watchdog character device and if needed the legacy * /dev/watchdog device. */ static void watchdog_cdev_unregister(struct watchdog_device *wdd) { struct watchdog_core_data *wd_data = wdd->wd_data; cdev_del(&wd_data->cdev); if (wdd->id == 0) { misc_deregister(&watchdog_miscdev); old_wd_data = NULL; } mutex_lock(&wd_data->lock); wd_data->wdd = NULL; wdd->wd_data = NULL; mutex_unlock(&wd_data->lock); kref_put(&wd_data->kref, watchdog_core_data_release); } static struct class watchdog_class = { .name = "watchdog", .owner = THIS_MODULE, .dev_groups = wdt_groups, }; /* * watchdog_dev_register: register a watchdog device * @wdd: 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 *wdd) { struct device *dev; dev_t devno; int ret; devno = MKDEV(MAJOR(watchdog_devt), wdd->id); ret = watchdog_cdev_register(wdd, devno); if (ret) return ret; dev = device_create(&watchdog_class, wdd->parent, devno, wdd, "watchdog%d", wdd->id); if (IS_ERR(dev)) { watchdog_cdev_unregister(wdd); return PTR_ERR(dev); } wdd->dev = dev; return ret; } /* * watchdog_dev_unregister: unregister a watchdog device * @watchdog: watchdog device * * Unregister watchdog device and if needed the legacy * /dev/watchdog device. */ void watchdog_dev_unregister(struct watchdog_device *wdd) { device_destroy(&watchdog_class, wdd->dev->devt); wdd->dev = NULL; watchdog_cdev_unregister(wdd); } /* * 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; err = class_register(&watchdog_class); if (err < 0) { pr_err("couldn't register class\n"); return err; } err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog"); if (err < 0) { pr_err("watchdog: unable to allocate char dev region\n"); class_unregister(&watchdog_class); return err; } return 0; } /* * 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); class_unregister(&watchdog_class); }