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| 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 | |
| 40 | #include "watchdog_core.h" /* For watchdog_dev_register/... */ |
| 41 | |
| 42 | static DEFINE_IDA(watchdog_ida); |
| 43 | static struct class *watchdog_class; |
| 44 | |
| 45 | /** |
| 46 | * watchdog_register_device() - register a watchdog device |
| 47 | * @wdd: watchdog device |
| 48 | * |
| 49 | * Register a watchdog device with the kernel so that the |
| 50 | * watchdog timer can be accessed from userspace. |
| 51 | * |
| 52 | * A zero is returned on success and a negative errno code for |
| 53 | * failure. |
| 54 | */ |
| 55 | int watchdog_register_device(struct watchdog_device *wdd) |
| 56 | { |
| 57 | int ret, id, devno; |
| 58 | |
| 59 | if (wdd == NULL || wdd->info == NULL || wdd->ops == NULL) |
| 60 | return -EINVAL; |
| 61 | |
| 62 | /* Mandatory operations need to be supported */ |
| 63 | if (wdd->ops->start == NULL || wdd->ops->stop == NULL) |
| 64 | return -EINVAL; |
| 65 | |
| 66 | /* |
| 67 | * Check that we have valid min and max timeout values, if |
| 68 | * not reset them both to 0 (=not used or unknown) |
| 69 | */ |
| 70 | if (wdd->min_timeout > wdd->max_timeout) { |
| 71 | pr_info("Invalid min and max timeout values, resetting to 0!\n"); |
| 72 | wdd->min_timeout = 0; |
| 73 | wdd->max_timeout = 0; |
| 74 | } |
| 75 | |
| 76 | /* |
| 77 | * Note: now that all watchdog_device data has been verified, we |
| 78 | * will not check this anymore in other functions. If data gets |
| 79 | * corrupted in a later stage then we expect a kernel panic! |
| 80 | */ |
| 81 | |
| 82 | mutex_init(&wdd->lock); |
| 83 | id = ida_simple_get(&watchdog_ida, 0, MAX_DOGS, GFP_KERNEL); |
| 84 | if (id < 0) |
| 85 | return id; |
| 86 | wdd->id = id; |
| 87 | |
| 88 | ret = watchdog_dev_register(wdd); |
| 89 | if (ret) { |
| 90 | ida_simple_remove(&watchdog_ida, id); |
| 91 | if (!(id == 0 && ret == -EBUSY)) |
| 92 | return ret; |
| 93 | |
| 94 | /* Retry in case a legacy watchdog module exists */ |
| 95 | id = ida_simple_get(&watchdog_ida, 1, MAX_DOGS, GFP_KERNEL); |
| 96 | if (id < 0) |
| 97 | return id; |
| 98 | wdd->id = id; |
| 99 | |
| 100 | ret = watchdog_dev_register(wdd); |
| 101 | if (ret) { |
| 102 | ida_simple_remove(&watchdog_ida, id); |
| 103 | return ret; |
| 104 | } |
| 105 | } |
| 106 | |
| 107 | devno = wdd->cdev.dev; |
| 108 | wdd->dev = device_create(watchdog_class, wdd->parent, devno, |
| 109 | NULL, "watchdog%d", wdd->id); |
| 110 | if (IS_ERR(wdd->dev)) { |
| 111 | watchdog_dev_unregister(wdd); |
| 112 | ida_simple_remove(&watchdog_ida, id); |
| 113 | ret = PTR_ERR(wdd->dev); |
| 114 | return ret; |
| 115 | } |
| 116 | |
| 117 | return 0; |
| 118 | } |
| 119 | EXPORT_SYMBOL_GPL(watchdog_register_device); |
| 120 | |
| 121 | /** |
| 122 | * watchdog_unregister_device() - unregister a watchdog device |
| 123 | * @wdd: watchdog device to unregister |
| 124 | * |
| 125 | * Unregister a watchdog device that was previously successfully |
| 126 | * registered with watchdog_register_device(). |
| 127 | */ |
| 128 | void watchdog_unregister_device(struct watchdog_device *wdd) |
| 129 | { |
| 130 | int ret; |
| 131 | int devno; |
| 132 | |
| 133 | if (wdd == NULL) |
| 134 | return; |
| 135 | |
| 136 | devno = wdd->cdev.dev; |
| 137 | ret = watchdog_dev_unregister(wdd); |
| 138 | if (ret) |
| 139 | pr_err("error unregistering /dev/watchdog (err=%d)\n", ret); |
| 140 | device_destroy(watchdog_class, devno); |
| 141 | ida_simple_remove(&watchdog_ida, wdd->id); |
| 142 | wdd->dev = NULL; |
| 143 | } |
| 144 | EXPORT_SYMBOL_GPL(watchdog_unregister_device); |
| 145 | |
| 146 | static int __init watchdog_init(void) |
| 147 | { |
| 148 | int err; |
| 149 | |
| 150 | watchdog_class = class_create(THIS_MODULE, "watchdog"); |
| 151 | if (IS_ERR(watchdog_class)) { |
| 152 | pr_err("couldn't create class\n"); |
| 153 | return PTR_ERR(watchdog_class); |
| 154 | } |
| 155 | |
| 156 | err = watchdog_dev_init(); |
| 157 | if (err < 0) { |
| 158 | class_destroy(watchdog_class); |
| 159 | return err; |
| 160 | } |
| 161 | |
| 162 | return 0; |
| 163 | } |
| 164 | |
| 165 | static void __exit watchdog_exit(void) |
| 166 | { |
| 167 | watchdog_dev_exit(); |
| 168 | class_destroy(watchdog_class); |
| 169 | ida_destroy(&watchdog_ida); |
| 170 | } |
| 171 | |
| 172 | subsys_initcall(watchdog_init); |
| 173 | module_exit(watchdog_exit); |
| 174 | |
| 175 | MODULE_AUTHOR("Alan Cox <alan@lxorguk.ukuu.org.uk>"); |
| 176 | MODULE_AUTHOR("Wim Van Sebroeck <wim@iguana.be>"); |
| 177 | MODULE_DESCRIPTION("WatchDog Timer Driver Core"); |
| 178 | MODULE_LICENSE("GPL"); |
| 179 |
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