/* * 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 <linux/idr.h> /* For ida_* macros */ #include <linux/err.h> /* For IS_ERR macros */ #include <linux/of.h> /* For of_get_timeout_sec */ #include "watchdog_core.h" /* For watchdog_dev_register/... */ static DEFINE_IDA(watchdog_ida); static struct class *watchdog_class; static void watchdog_check_min_max_timeout(struct watchdog_device *wdd) { /* * Check that we have valid min and max timeout values, if * not reset them both to 0 (=not used or unknown) */ if (wdd->min_timeout > wdd->max_timeout) { pr_info("Invalid min and max timeout values, resetting to 0!\n"); wdd->min_timeout = 0; wdd->max_timeout = 0; } } /** * watchdog_init_timeout() - initialize the timeout field * @timeout_parm: timeout module parameter * @dev: Device that stores the timeout-sec property * * Initialize the timeout field of the watchdog_device struct with either the * timeout module parameter (if it is valid value) or the timeout-sec property * (only if it is a valid value and the timeout_parm is out of bounds). * If none of them are valid then we keep the old value (which should normally * be the default timeout value. * * A zero is returned on success and -EINVAL for failure. */ int watchdog_init_timeout(struct watchdog_device *wdd, unsigned int timeout_parm, struct device *dev) { unsigned int t = 0; int ret = 0; watchdog_check_min_max_timeout(wdd); /* try to get the timeout module parameter first */ if (!watchdog_timeout_invalid(wdd, timeout_parm) && timeout_parm) { wdd->timeout = timeout_parm; return ret; } if (timeout_parm) ret = -EINVAL; /* try to get the timeout_sec property */ if (dev == NULL || dev->of_node == NULL) return ret; of_property_read_u32(dev->of_node, "timeout-sec", &t); if (!watchdog_timeout_invalid(wdd, t) && t) wdd->timeout = t; else ret = -EINVAL; return ret; } EXPORT_SYMBOL_GPL(watchdog_init_timeout); /** * 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, id, devno; 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; watchdog_check_min_max_timeout(wdd); /* * 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! */ mutex_init(&wdd->lock); id = ida_simple_get(&watchdog_ida, 0, MAX_DOGS, GFP_KERNEL); if (id < 0) return id; wdd->id = id; ret = watchdog_dev_register(wdd); if (ret) { ida_simple_remove(&watchdog_ida, id); if (!(id == 0 && ret == -EBUSY)) return ret; /* Retry in case a legacy watchdog module exists */ id = ida_simple_get(&watchdog_ida, 1, MAX_DOGS, GFP_KERNEL); if (id < 0) return id; wdd->id = id; ret = watchdog_dev_register(wdd); if (ret) { ida_simple_remove(&watchdog_ida, id); return ret; } } devno = wdd->cdev.dev; wdd->dev = device_create(watchdog_class, wdd->parent, devno, NULL, "watchdog%d", wdd->id); if (IS_ERR(wdd->dev)) { watchdog_dev_unregister(wdd); ida_simple_remove(&watchdog_ida, id); ret = PTR_ERR(wdd->dev); 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; int devno; if (wdd == NULL) return; devno = wdd->cdev.dev; ret = watchdog_dev_unregister(wdd); if (ret) pr_err("error unregistering /dev/watchdog (err=%d)\n", ret); device_destroy(watchdog_class, devno); ida_simple_remove(&watchdog_ida, wdd->id); wdd->dev = NULL; } EXPORT_SYMBOL_GPL(watchdog_unregister_device); static int __init watchdog_init(void) { int err; watchdog_class = class_create(THIS_MODULE, "watchdog"); if (IS_ERR(watchdog_class)) { pr_err("couldn't create class\n"); return PTR_ERR(watchdog_class); } err = watchdog_dev_init(); if (err < 0) { class_destroy(watchdog_class); return err; } return 0; } static void __exit watchdog_exit(void) { watchdog_dev_exit(); class_destroy(watchdog_class); ida_destroy(&watchdog_ida); } subsys_initcall(watchdog_init); module_exit(watchdog_exit); 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");