1 /* 2 * watchdog_core.c 3 * 4 * (c) Copyright 2008-2011 Alan Cox <alan@lxorguk.ukuu.org.uk>, 5 * All Rights Reserved. 6 * 7 * (c) Copyright 2008-2011 Wim Van Sebroeck <wim@iguana.be>. 8 * 9 * This source code is part of the generic code that can be used 10 * by all the watchdog timer drivers. 11 * 12 * Based on source code of the following authors: 13 * Matt Domsch <Matt_Domsch@dell.com>, 14 * Rob Radez <rob@osinvestor.com>, 15 * Rusty Lynch <rusty@linux.co.intel.com> 16 * Satyam Sharma <satyam@infradead.org> 17 * Randy Dunlap <randy.dunlap@oracle.com> 18 * 19 * This program is free software; you can redistribute it and/or 20 * modify it under the terms of the GNU General Public License 21 * as published by the Free Software Foundation; either version 22 * 2 of the License, or (at your option) any later version. 23 * 24 * Neither Alan Cox, CymruNet Ltd., Wim Van Sebroeck nor Iguana vzw. 25 * admit liability nor provide warranty for any of this software. 26 * This material is provided "AS-IS" and at no charge. 27 */ 28 29 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 30 31 #include <linux/module.h> /* For EXPORT_SYMBOL/module stuff/... */ 32 #include <linux/types.h> /* For standard types */ 33 #include <linux/errno.h> /* For the -ENODEV/... values */ 34 #include <linux/kernel.h> /* For printk/panic/... */ 35 #include <linux/watchdog.h> /* For watchdog specific items */ 36 #include <linux/init.h> /* For __init/__exit/... */ 37 #include <linux/idr.h> /* For ida_* macros */ 38 #include <linux/err.h> /* For IS_ERR macros */ 39 #include <linux/of.h> /* For of_get_timeout_sec */ 40 41 #include "watchdog_core.h" /* For watchdog_dev_register/... */ 42 43 static DEFINE_IDA(watchdog_ida); 44 static struct class *watchdog_class; 45 46 static void watchdog_check_min_max_timeout(struct watchdog_device *wdd) 47 { 48 /* 49 * Check that we have valid min and max timeout values, if 50 * not reset them both to 0 (=not used or unknown) 51 */ 52 if (wdd->min_timeout > wdd->max_timeout) { 53 pr_info("Invalid min and max timeout values, resetting to 0!\n"); 54 wdd->min_timeout = 0; 55 wdd->max_timeout = 0; 56 } 57 } 58 59 /** 60 * watchdog_init_timeout() - initialize the timeout field 61 * @timeout_parm: timeout module parameter 62 * @dev: Device that stores the timeout-sec property 63 * 64 * Initialize the timeout field of the watchdog_device struct with either the 65 * timeout module parameter (if it is valid value) or the timeout-sec property 66 * (only if it is a valid value and the timeout_parm is out of bounds). 67 * If none of them are valid then we keep the old value (which should normally 68 * be the default timeout value. 69 * 70 * A zero is returned on success and -EINVAL for failure. 71 */ 72 int watchdog_init_timeout(struct watchdog_device *wdd, 73 unsigned int timeout_parm, struct device *dev) 74 { 75 unsigned int t = 0; 76 int ret = 0; 77 78 watchdog_check_min_max_timeout(wdd); 79 80 /* try to get the timeout module parameter first */ 81 if (!watchdog_timeout_invalid(wdd, timeout_parm) && timeout_parm) { 82 wdd->timeout = timeout_parm; 83 return ret; 84 } 85 if (timeout_parm) 86 ret = -EINVAL; 87 88 /* try to get the timeout_sec property */ 89 if (dev == NULL || dev->of_node == NULL) 90 return ret; 91 of_property_read_u32(dev->of_node, "timeout-sec", &t); 92 if (!watchdog_timeout_invalid(wdd, t) && t) 93 wdd->timeout = t; 94 else 95 ret = -EINVAL; 96 97 return ret; 98 } 99 EXPORT_SYMBOL_GPL(watchdog_init_timeout); 100 101 /** 102 * watchdog_register_device() - register a watchdog device 103 * @wdd: watchdog device 104 * 105 * Register a watchdog device with the kernel so that the 106 * watchdog timer can be accessed from userspace. 107 * 108 * A zero is returned on success and a negative errno code for 109 * failure. 110 */ 111 int watchdog_register_device(struct watchdog_device *wdd) 112 { 113 int ret, id, devno; 114 115 if (wdd == NULL || wdd->info == NULL || wdd->ops == NULL) 116 return -EINVAL; 117 118 /* Mandatory operations need to be supported */ 119 if (wdd->ops->start == NULL || wdd->ops->stop == NULL) 120 return -EINVAL; 121 122 watchdog_check_min_max_timeout(wdd); 123 124 /* 125 * Note: now that all watchdog_device data has been verified, we 126 * will not check this anymore in other functions. If data gets 127 * corrupted in a later stage then we expect a kernel panic! 128 */ 129 130 mutex_init(&wdd->lock); 131 id = ida_simple_get(&watchdog_ida, 0, MAX_DOGS, GFP_KERNEL); 132 if (id < 0) 133 return id; 134 wdd->id = id; 135 136 ret = watchdog_dev_register(wdd); 137 if (ret) { 138 ida_simple_remove(&watchdog_ida, id); 139 if (!(id == 0 && ret == -EBUSY)) 140 return ret; 141 142 /* Retry in case a legacy watchdog module exists */ 143 id = ida_simple_get(&watchdog_ida, 1, MAX_DOGS, GFP_KERNEL); 144 if (id < 0) 145 return id; 146 wdd->id = id; 147 148 ret = watchdog_dev_register(wdd); 149 if (ret) { 150 ida_simple_remove(&watchdog_ida, id); 151 return ret; 152 } 153 } 154 155 devno = wdd->cdev.dev; 156 wdd->dev = device_create(watchdog_class, wdd->parent, devno, 157 NULL, "watchdog%d", wdd->id); 158 if (IS_ERR(wdd->dev)) { 159 watchdog_dev_unregister(wdd); 160 ida_simple_remove(&watchdog_ida, id); 161 ret = PTR_ERR(wdd->dev); 162 return ret; 163 } 164 165 return 0; 166 } 167 EXPORT_SYMBOL_GPL(watchdog_register_device); 168 169 /** 170 * watchdog_unregister_device() - unregister a watchdog device 171 * @wdd: watchdog device to unregister 172 * 173 * Unregister a watchdog device that was previously successfully 174 * registered with watchdog_register_device(). 175 */ 176 void watchdog_unregister_device(struct watchdog_device *wdd) 177 { 178 int ret; 179 int devno; 180 181 if (wdd == NULL) 182 return; 183 184 devno = wdd->cdev.dev; 185 ret = watchdog_dev_unregister(wdd); 186 if (ret) 187 pr_err("error unregistering /dev/watchdog (err=%d)\n", ret); 188 device_destroy(watchdog_class, devno); 189 ida_simple_remove(&watchdog_ida, wdd->id); 190 wdd->dev = NULL; 191 } 192 EXPORT_SYMBOL_GPL(watchdog_unregister_device); 193 194 static int __init watchdog_init(void) 195 { 196 int err; 197 198 watchdog_class = class_create(THIS_MODULE, "watchdog"); 199 if (IS_ERR(watchdog_class)) { 200 pr_err("couldn't create class\n"); 201 return PTR_ERR(watchdog_class); 202 } 203 204 err = watchdog_dev_init(); 205 if (err < 0) { 206 class_destroy(watchdog_class); 207 return err; 208 } 209 210 return 0; 211 } 212 213 static void __exit watchdog_exit(void) 214 { 215 watchdog_dev_exit(); 216 class_destroy(watchdog_class); 217 ida_destroy(&watchdog_ida); 218 } 219 220 subsys_initcall(watchdog_init); 221 module_exit(watchdog_exit); 222 223 MODULE_AUTHOR("Alan Cox <alan@lxorguk.ukuu.org.uk>"); 224 MODULE_AUTHOR("Wim Van Sebroeck <wim@iguana.be>"); 225 MODULE_DESCRIPTION("WatchDog Timer Driver Core"); 226 MODULE_LICENSE("GPL"); 227