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1da177e4 LT |
1 | /* |
2 | * Acquire Single Board Computer Watchdog Timer driver | |
3 | * | |
4 | * Based on wdt.c. Original copyright messages: | |
5 | * | |
6 | * (c) Copyright 1996 Alan Cox <alan@redhat.com>, All Rights Reserved. | |
7 | * http://www.redhat.com | |
8 | * | |
9 | * This program is free software; you can redistribute it and/or | |
10 | * modify it under the terms of the GNU General Public License | |
11 | * as published by the Free Software Foundation; either version | |
12 | * 2 of the License, or (at your option) any later version. | |
13 | * | |
14 | * Neither Alan Cox nor CymruNet Ltd. admit liability nor provide | |
15 | * warranty for any of this software. This material is provided | |
16 | * "AS-IS" and at no charge. | |
17 | * | |
18 | * (c) Copyright 1995 Alan Cox <alan@redhat.com> | |
19 | * | |
20 | * 14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com> | |
21 | * Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT | |
22 | * Can't add timeout - driver doesn't allow changing value | |
23 | */ | |
24 | ||
25 | /* | |
26 | * Theory of Operation: | |
27 | * The Watch-Dog Timer is provided to ensure that standalone | |
28 | * Systems can always recover from catastrophic conditions that | |
29 | * caused the CPU to crash. This condition may have occured by | |
30 | * external EMI or a software bug. When the CPU stops working | |
31 | * correctly, hardware on the board will either perform a hardware | |
32 | * reset (cold boot) or a non-maskable interrupt (NMI) to bring the | |
33 | * system back to a known state. | |
34 | * | |
35 | * The Watch-Dog Timer is controlled by two I/O Ports. | |
36 | * 443 hex - Read - Enable or refresh the Watch-Dog Timer | |
37 | * 043 hex - Read - Disable the Watch-Dog Timer | |
38 | * | |
39 | * To enable the Watch-Dog Timer, a read from I/O port 443h must | |
40 | * be performed. This will enable and activate the countdown timer | |
41 | * which will eventually time out and either reset the CPU or cause | |
42 | * an NMI depending on the setting of a jumper. To ensure that this | |
43 | * reset condition does not occur, the Watch-Dog Timer must be | |
44 | * periodically refreshed by reading the same I/O port 443h. | |
45 | * The Watch-Dog Timer is disabled by reading I/O port 043h. | |
46 | * | |
47 | * The Watch-Dog Timer Time-Out Period is set via jumpers. | |
48 | * It can be 1, 2, 10, 20, 110 or 220 seconds. | |
49 | */ | |
50 | ||
76c11f04 WVS |
51 | /* |
52 | * Includes, defines, variables, module parameters, ... | |
53 | */ | |
1da177e4 | 54 | |
76c11f04 WVS |
55 | /* Includes */ |
56 | #include <linux/module.h> /* For module specific items */ | |
57 | #include <linux/moduleparam.h> /* For new moduleparam's */ | |
58 | #include <linux/types.h> /* For standard types (like size_t) */ | |
59 | #include <linux/errno.h> /* For the -ENODEV/... values */ | |
60 | #include <linux/kernel.h> /* For printk/panic/... */ | |
61 | #include <linux/miscdevice.h> /* For MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR) */ | |
62 | #include <linux/watchdog.h> /* For the watchdog specific items */ | |
63 | #include <linux/fs.h> /* For file operations */ | |
64 | #include <linux/ioport.h> /* For io-port access */ | |
65 | #include <linux/notifier.h> /* For reboot notifier */ | |
66 | #include <linux/reboot.h> /* For reboot notifier */ | |
67 | #include <linux/init.h> /* For __init/__exit/... */ | |
68 | ||
69 | #include <asm/uaccess.h> /* For copy_to_user/put_user/... */ | |
70 | #include <asm/io.h> /* For inb/outb/... */ | |
71 | ||
72 | /* Module information */ | |
73 | #define DRV_NAME "acquirewdt" | |
74 | #define PFX DRV_NAME ": " | |
1da177e4 | 75 | #define WATCHDOG_NAME "Acquire WDT" |
1da177e4 LT |
76 | #define WATCHDOG_HEARTBEAT 0 /* There is no way to see what the correct time-out period is */ |
77 | ||
76c11f04 | 78 | /* internal variables */ |
1da177e4 LT |
79 | static unsigned long acq_is_open; |
80 | static char expect_close; | |
81 | ||
76c11f04 WVS |
82 | /* module parameters */ |
83 | static int wdt_stop = 0x43; /* You must set this - there is no sane way to probe for this board. */ | |
1da177e4 LT |
84 | module_param(wdt_stop, int, 0); |
85 | MODULE_PARM_DESC(wdt_stop, "Acquire WDT 'stop' io port (default 0x43)"); | |
86 | ||
76c11f04 | 87 | static int wdt_start = 0x443; /* You must set this - there is no sane way to probe for this board. */ |
1da177e4 LT |
88 | module_param(wdt_start, int, 0); |
89 | MODULE_PARM_DESC(wdt_start, "Acquire WDT 'start' io port (default 0x443)"); | |
90 | ||
4bfdf378 | 91 | static int nowayout = WATCHDOG_NOWAYOUT; |
1da177e4 | 92 | module_param(nowayout, int, 0); |
76c11f04 | 93 | MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); |
1da177e4 LT |
94 | |
95 | /* | |
76c11f04 | 96 | * Watchdog Operations |
1da177e4 LT |
97 | */ |
98 | ||
99 | static void acq_keepalive(void) | |
100 | { | |
101 | /* Write a watchdog value */ | |
102 | inb_p(wdt_start); | |
103 | } | |
104 | ||
105 | static void acq_stop(void) | |
106 | { | |
107 | /* Turn the card off */ | |
108 | inb_p(wdt_stop); | |
109 | } | |
110 | ||
111 | /* | |
76c11f04 | 112 | * /dev/watchdog handling |
1da177e4 LT |
113 | */ |
114 | ||
115 | static ssize_t acq_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) | |
116 | { | |
117 | /* See if we got the magic character 'V' and reload the timer */ | |
118 | if(count) { | |
119 | if (!nowayout) { | |
120 | size_t i; | |
121 | ||
122 | /* note: just in case someone wrote the magic character | |
123 | * five months ago... */ | |
124 | expect_close = 0; | |
125 | ||
126 | /* scan to see whether or not we got the magic character */ | |
127 | for (i = 0; i != count; i++) { | |
128 | char c; | |
129 | if (get_user(c, buf + i)) | |
130 | return -EFAULT; | |
131 | if (c == 'V') | |
132 | expect_close = 42; | |
133 | } | |
134 | } | |
135 | ||
136 | /* Well, anyhow someone wrote to us, we should return that favour */ | |
137 | acq_keepalive(); | |
138 | } | |
139 | return count; | |
140 | } | |
141 | ||
142 | static int acq_ioctl(struct inode *inode, struct file *file, unsigned int cmd, | |
143 | unsigned long arg) | |
144 | { | |
145 | int options, retval = -EINVAL; | |
146 | void __user *argp = (void __user *)arg; | |
147 | int __user *p = argp; | |
148 | static struct watchdog_info ident = | |
149 | { | |
150 | .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE, | |
151 | .firmware_version = 1, | |
76c11f04 | 152 | .identity = WATCHDOG_NAME, |
1da177e4 LT |
153 | }; |
154 | ||
155 | switch(cmd) | |
156 | { | |
157 | case WDIOC_GETSUPPORT: | |
158 | return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0; | |
159 | ||
160 | case WDIOC_GETSTATUS: | |
161 | case WDIOC_GETBOOTSTATUS: | |
162 | return put_user(0, p); | |
163 | ||
164 | case WDIOC_KEEPALIVE: | |
165 | acq_keepalive(); | |
166 | return 0; | |
167 | ||
168 | case WDIOC_GETTIMEOUT: | |
169 | return put_user(WATCHDOG_HEARTBEAT, p); | |
170 | ||
171 | case WDIOC_SETOPTIONS: | |
172 | { | |
173 | if (get_user(options, p)) | |
174 | return -EFAULT; | |
175 | ||
176 | if (options & WDIOS_DISABLECARD) | |
177 | { | |
178 | acq_stop(); | |
179 | retval = 0; | |
180 | } | |
181 | ||
182 | if (options & WDIOS_ENABLECARD) | |
183 | { | |
184 | acq_keepalive(); | |
185 | retval = 0; | |
186 | } | |
187 | ||
188 | return retval; | |
189 | } | |
190 | ||
191 | default: | |
795b89d2 | 192 | return -ENOTTY; |
1da177e4 LT |
193 | } |
194 | } | |
195 | ||
196 | static int acq_open(struct inode *inode, struct file *file) | |
197 | { | |
198 | if (test_and_set_bit(0, &acq_is_open)) | |
199 | return -EBUSY; | |
200 | ||
201 | if (nowayout) | |
202 | __module_get(THIS_MODULE); | |
203 | ||
204 | /* Activate */ | |
205 | acq_keepalive(); | |
206 | return nonseekable_open(inode, file); | |
207 | } | |
208 | ||
209 | static int acq_close(struct inode *inode, struct file *file) | |
210 | { | |
211 | if (expect_close == 42) { | |
212 | acq_stop(); | |
213 | } else { | |
214 | printk(KERN_CRIT PFX "Unexpected close, not stopping watchdog!\n"); | |
215 | acq_keepalive(); | |
216 | } | |
217 | clear_bit(0, &acq_is_open); | |
218 | expect_close = 0; | |
219 | return 0; | |
220 | } | |
221 | ||
222 | /* | |
223 | * Notifier for system down | |
224 | */ | |
225 | ||
226 | static int acq_notify_sys(struct notifier_block *this, unsigned long code, | |
227 | void *unused) | |
228 | { | |
229 | if(code==SYS_DOWN || code==SYS_HALT) { | |
230 | /* Turn the WDT off */ | |
231 | acq_stop(); | |
232 | } | |
233 | return NOTIFY_DONE; | |
234 | } | |
235 | ||
236 | /* | |
237 | * Kernel Interfaces | |
238 | */ | |
239 | ||
62322d25 | 240 | static const struct file_operations acq_fops = { |
1da177e4 LT |
241 | .owner = THIS_MODULE, |
242 | .llseek = no_llseek, | |
243 | .write = acq_write, | |
244 | .ioctl = acq_ioctl, | |
245 | .open = acq_open, | |
246 | .release = acq_close, | |
247 | }; | |
248 | ||
76c11f04 WVS |
249 | static struct miscdevice acq_miscdev = { |
250 | .minor = WATCHDOG_MINOR, | |
251 | .name = "watchdog", | |
252 | .fops = &acq_fops, | |
1da177e4 LT |
253 | }; |
254 | ||
255 | /* | |
256 | * The WDT card needs to learn about soft shutdowns in order to | |
257 | * turn the timebomb registers off. | |
258 | */ | |
259 | ||
76c11f04 | 260 | static struct notifier_block acq_notifier = { |
1da177e4 LT |
261 | .notifier_call = acq_notify_sys, |
262 | }; | |
263 | ||
76c11f04 WVS |
264 | /* |
265 | * Init & exit routines | |
266 | */ | |
267 | ||
1da177e4 LT |
268 | static int __init acq_init(void) |
269 | { | |
270 | int ret; | |
271 | ||
272 | printk(KERN_INFO "WDT driver for Acquire single board computer initialising.\n"); | |
273 | ||
274 | if (wdt_stop != wdt_start) { | |
275 | if (!request_region(wdt_stop, 1, WATCHDOG_NAME)) { | |
276 | printk (KERN_ERR PFX "I/O address 0x%04x already in use\n", | |
277 | wdt_stop); | |
278 | ret = -EIO; | |
279 | goto out; | |
280 | } | |
281 | } | |
282 | ||
283 | if (!request_region(wdt_start, 1, WATCHDOG_NAME)) { | |
284 | printk (KERN_ERR PFX "I/O address 0x%04x already in use\n", | |
285 | wdt_start); | |
286 | ret = -EIO; | |
287 | goto unreg_stop; | |
288 | } | |
289 | ||
290 | ret = register_reboot_notifier(&acq_notifier); | |
291 | if (ret != 0) { | |
292 | printk (KERN_ERR PFX "cannot register reboot notifier (err=%d)\n", | |
293 | ret); | |
294 | goto unreg_regions; | |
295 | } | |
296 | ||
297 | ret = misc_register(&acq_miscdev); | |
298 | if (ret != 0) { | |
299 | printk (KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n", | |
300 | WATCHDOG_MINOR, ret); | |
301 | goto unreg_reboot; | |
302 | } | |
303 | ||
304 | printk (KERN_INFO PFX "initialized. (nowayout=%d)\n", | |
305 | nowayout); | |
306 | ||
307 | return 0; | |
308 | ||
309 | unreg_reboot: | |
310 | unregister_reboot_notifier(&acq_notifier); | |
311 | unreg_regions: | |
312 | release_region(wdt_start, 1); | |
313 | unreg_stop: | |
314 | if (wdt_stop != wdt_start) | |
315 | release_region(wdt_stop, 1); | |
316 | out: | |
317 | return ret; | |
318 | } | |
319 | ||
320 | static void __exit acq_exit(void) | |
321 | { | |
322 | misc_deregister(&acq_miscdev); | |
323 | unregister_reboot_notifier(&acq_notifier); | |
76c11f04 | 324 | release_region(wdt_start,1); |
1da177e4 LT |
325 | if(wdt_stop != wdt_start) |
326 | release_region(wdt_stop,1); | |
1da177e4 LT |
327 | } |
328 | ||
329 | module_init(acq_init); | |
330 | module_exit(acq_exit); | |
331 | ||
332 | MODULE_AUTHOR("David Woodhouse"); | |
333 | MODULE_DESCRIPTION("Acquire Inc. Single Board Computer Watchdog Timer driver"); | |
334 | MODULE_LICENSE("GPL"); | |
335 | MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); |