1 /*
2 * 60xx Single Board Computer Watchdog Timer driver for Linux 2.2.x
3 *
4 * Based on acquirewdt.c by Alan Cox.
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 *
11 * The author does NOT admit liability nor provide warranty for
12 * any of this software. This material is provided "AS-IS" in
13 * the hope that it may be useful for others.
14 *
15 * (c) Copyright 2000 Jakob Oestergaard <jakob@unthought.net>
16 *
17 * 12/4 - 2000 [Initial revision]
18 * 25/4 - 2000 Added /dev/watchdog support
19 * 09/5 - 2001 [smj@oro.net] fixed fop_write to "return 1"
20 * on success
21 * 12/4 - 2002 [rob@osinvestor.com] eliminate fop_read
22 * fix possible wdt_is_open race
23 * add CONFIG_WATCHDOG_NOWAYOUT support
24 * remove lock_kernel/unlock_kernel pairs
25 * added KERN_* to printk's
26 * got rid of extraneous comments
27 * changed watchdog_info to correctly reflect what
28 * the driver offers
29 * added WDIOC_GETSTATUS, WDIOC_GETBOOTSTATUS,
30 * WDIOC_SETTIMEOUT, WDIOC_GETTIMEOUT, and
31 * WDIOC_SETOPTIONS ioctls
32 * 09/8 - 2003 [wim@iguana.be] cleanup of trailing spaces
33 * use module_param
34 * made timeout (the emulated heartbeat) a
35 * module_param
36 * made the keepalive ping an internal subroutine
37 * made wdt_stop and wdt_start module params
38 * added extra printk's for startup problems
39 * added MODULE_AUTHOR and MODULE_DESCRIPTION info
40 *
41 *
42 * This WDT driver is different from the other Linux WDT
43 * drivers in the following ways:
44 * *) The driver will ping the watchdog by itself, because this
45 * particular WDT has a very short timeout (one second) and it
46 * would be insane to count on any userspace daemon always
47 * getting scheduled within that time frame.
48 *
49 */
50
51 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
52
53 #include <linux/module.h>
54 #include <linux/moduleparam.h>
55 #include <linux/types.h>
56 #include <linux/timer.h>
57 #include <linux/jiffies.h>
58 #include <linux/miscdevice.h>
59 #include <linux/watchdog.h>
60 #include <linux/fs.h>
61 #include <linux/ioport.h>
62 #include <linux/notifier.h>
63 #include <linux/reboot.h>
64 #include <linux/init.h>
65 #include <linux/io.h>
66 #include <linux/uaccess.h>
67
68
69 #define OUR_NAME "sbc60xxwdt"
70 #define PFX OUR_NAME ": "
71
72 /*
73 * You must set these - The driver cannot probe for the settings
74 */
75
76 static int wdt_stop = 0x45;
77 module_param(wdt_stop, int, 0);
78 MODULE_PARM_DESC(wdt_stop, "SBC60xx WDT 'stop' io port (default 0x45)");
79
80 static int wdt_start = 0x443;
81 module_param(wdt_start, int, 0);
82 MODULE_PARM_DESC(wdt_start, "SBC60xx WDT 'start' io port (default 0x443)");
83
84 /*
85 * The 60xx board can use watchdog timeout values from one second
86 * to several minutes. The default is one second, so if we reset
87 * the watchdog every ~250ms we should be safe.
88 */
89
90 #define WDT_INTERVAL (HZ/4+1)
91
92 /*
93 * We must not require too good response from the userspace daemon.
94 * Here we require the userspace daemon to send us a heartbeat
95 * char to /dev/watchdog every 30 seconds.
96 * If the daemon pulses us every 25 seconds, we can still afford
97 * a 5 second scheduling delay on the (high priority) daemon. That
98 * should be sufficient for a box under any load.
99 */
100
101 #define WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */
102 static int timeout = WATCHDOG_TIMEOUT; /* in seconds, multiplied by HZ to
103 get seconds to wait for a ping */
104 module_param(timeout, int, 0);
105 MODULE_PARM_DESC(timeout,
106 "Watchdog timeout in seconds. (1<=timeout<=3600, default="
107 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
108
109 static bool nowayout = WATCHDOG_NOWAYOUT;
110 module_param(nowayout, bool, 0);
111 MODULE_PARM_DESC(nowayout,
112 "Watchdog cannot be stopped once started (default="
113 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
114
115 static void wdt_timer_ping(unsigned long);
116 static DEFINE_TIMER(timer, wdt_timer_ping, 0, 0);
117 static unsigned long next_heartbeat;
118 static unsigned long wdt_is_open;
119 static char wdt_expect_close;
120
121 /*
122 * Whack the dog
123 */
124
wdt_timer_ping(unsigned long data)125 static void wdt_timer_ping(unsigned long data)
126 {
127 /* If we got a heartbeat pulse within the WDT_US_INTERVAL
128 * we agree to ping the WDT
129 */
130 if (time_before(jiffies, next_heartbeat)) {
131 /* Ping the WDT by reading from wdt_start */
132 inb_p(wdt_start);
133 /* Re-set the timer interval */
134 mod_timer(&timer, jiffies + WDT_INTERVAL);
135 } else
136 pr_warn("Heartbeat lost! Will not ping the watchdog\n");
137 }
138
139 /*
140 * Utility routines
141 */
142
wdt_startup(void)143 static void wdt_startup(void)
144 {
145 next_heartbeat = jiffies + (timeout * HZ);
146
147 /* Start the timer */
148 mod_timer(&timer, jiffies + WDT_INTERVAL);
149 pr_info("Watchdog timer is now enabled\n");
150 }
151
wdt_turnoff(void)152 static void wdt_turnoff(void)
153 {
154 /* Stop the timer */
155 del_timer(&timer);
156 inb_p(wdt_stop);
157 pr_info("Watchdog timer is now disabled...\n");
158 }
159
wdt_keepalive(void)160 static void wdt_keepalive(void)
161 {
162 /* user land ping */
163 next_heartbeat = jiffies + (timeout * HZ);
164 }
165
166 /*
167 * /dev/watchdog handling
168 */
169
fop_write(struct file * file,const char __user * buf,size_t count,loff_t * ppos)170 static ssize_t fop_write(struct file *file, const char __user *buf,
171 size_t count, loff_t *ppos)
172 {
173 /* See if we got the magic character 'V' and reload the timer */
174 if (count) {
175 if (!nowayout) {
176 size_t ofs;
177
178 /* note: just in case someone wrote the
179 magic character five months ago... */
180 wdt_expect_close = 0;
181
182 /* scan to see whether or not we got the
183 magic character */
184 for (ofs = 0; ofs != count; ofs++) {
185 char c;
186 if (get_user(c, buf + ofs))
187 return -EFAULT;
188 if (c == 'V')
189 wdt_expect_close = 42;
190 }
191 }
192
193 /* Well, anyhow someone wrote to us, we should
194 return that favour */
195 wdt_keepalive();
196 }
197 return count;
198 }
199
fop_open(struct inode * inode,struct file * file)200 static int fop_open(struct inode *inode, struct file *file)
201 {
202 /* Just in case we're already talking to someone... */
203 if (test_and_set_bit(0, &wdt_is_open))
204 return -EBUSY;
205
206 if (nowayout)
207 __module_get(THIS_MODULE);
208
209 /* Good, fire up the show */
210 wdt_startup();
211 return nonseekable_open(inode, file);
212 }
213
fop_close(struct inode * inode,struct file * file)214 static int fop_close(struct inode *inode, struct file *file)
215 {
216 if (wdt_expect_close == 42)
217 wdt_turnoff();
218 else {
219 del_timer(&timer);
220 pr_crit("device file closed unexpectedly. Will not stop the WDT!\n");
221 }
222 clear_bit(0, &wdt_is_open);
223 wdt_expect_close = 0;
224 return 0;
225 }
226
fop_ioctl(struct file * file,unsigned int cmd,unsigned long arg)227 static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
228 {
229 void __user *argp = (void __user *)arg;
230 int __user *p = argp;
231 static const struct watchdog_info ident = {
232 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
233 WDIOF_MAGICCLOSE,
234 .firmware_version = 1,
235 .identity = "SBC60xx",
236 };
237
238 switch (cmd) {
239 case WDIOC_GETSUPPORT:
240 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
241 case WDIOC_GETSTATUS:
242 case WDIOC_GETBOOTSTATUS:
243 return put_user(0, p);
244 case WDIOC_SETOPTIONS:
245 {
246 int new_options, retval = -EINVAL;
247 if (get_user(new_options, p))
248 return -EFAULT;
249 if (new_options & WDIOS_DISABLECARD) {
250 wdt_turnoff();
251 retval = 0;
252 }
253 if (new_options & WDIOS_ENABLECARD) {
254 wdt_startup();
255 retval = 0;
256 }
257 return retval;
258 }
259 case WDIOC_KEEPALIVE:
260 wdt_keepalive();
261 return 0;
262 case WDIOC_SETTIMEOUT:
263 {
264 int new_timeout;
265 if (get_user(new_timeout, p))
266 return -EFAULT;
267 /* arbitrary upper limit */
268 if (new_timeout < 1 || new_timeout > 3600)
269 return -EINVAL;
270
271 timeout = new_timeout;
272 wdt_keepalive();
273 /* Fall through */
274 }
275 case WDIOC_GETTIMEOUT:
276 return put_user(timeout, p);
277 default:
278 return -ENOTTY;
279 }
280 }
281
282 static const struct file_operations wdt_fops = {
283 .owner = THIS_MODULE,
284 .llseek = no_llseek,
285 .write = fop_write,
286 .open = fop_open,
287 .release = fop_close,
288 .unlocked_ioctl = fop_ioctl,
289 };
290
291 static struct miscdevice wdt_miscdev = {
292 .minor = WATCHDOG_MINOR,
293 .name = "watchdog",
294 .fops = &wdt_fops,
295 };
296
297 /*
298 * Notifier for system down
299 */
300
wdt_notify_sys(struct notifier_block * this,unsigned long code,void * unused)301 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
302 void *unused)
303 {
304 if (code == SYS_DOWN || code == SYS_HALT)
305 wdt_turnoff();
306 return NOTIFY_DONE;
307 }
308
309 /*
310 * The WDT needs to learn about soft shutdowns in order to
311 * turn the timebomb registers off.
312 */
313
314 static struct notifier_block wdt_notifier = {
315 .notifier_call = wdt_notify_sys,
316 };
317
sbc60xxwdt_unload(void)318 static void __exit sbc60xxwdt_unload(void)
319 {
320 wdt_turnoff();
321
322 /* Deregister */
323 misc_deregister(&wdt_miscdev);
324
325 unregister_reboot_notifier(&wdt_notifier);
326 if ((wdt_stop != 0x45) && (wdt_stop != wdt_start))
327 release_region(wdt_stop, 1);
328 release_region(wdt_start, 1);
329 }
330
sbc60xxwdt_init(void)331 static int __init sbc60xxwdt_init(void)
332 {
333 int rc = -EBUSY;
334
335 if (timeout < 1 || timeout > 3600) { /* arbitrary upper limit */
336 timeout = WATCHDOG_TIMEOUT;
337 pr_info("timeout value must be 1 <= x <= 3600, using %d\n",
338 timeout);
339 }
340
341 if (!request_region(wdt_start, 1, "SBC 60XX WDT")) {
342 pr_err("I/O address 0x%04x already in use\n", wdt_start);
343 rc = -EIO;
344 goto err_out;
345 }
346
347 /* We cannot reserve 0x45 - the kernel already has! */
348 if (wdt_stop != 0x45 && wdt_stop != wdt_start) {
349 if (!request_region(wdt_stop, 1, "SBC 60XX WDT")) {
350 pr_err("I/O address 0x%04x already in use\n", wdt_stop);
351 rc = -EIO;
352 goto err_out_region1;
353 }
354 }
355
356 rc = register_reboot_notifier(&wdt_notifier);
357 if (rc) {
358 pr_err("cannot register reboot notifier (err=%d)\n", rc);
359 goto err_out_region2;
360 }
361
362 rc = misc_register(&wdt_miscdev);
363 if (rc) {
364 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
365 wdt_miscdev.minor, rc);
366 goto err_out_reboot;
367 }
368 pr_info("WDT driver for 60XX single board computer initialised. timeout=%d sec (nowayout=%d)\n",
369 timeout, nowayout);
370
371 return 0;
372
373 err_out_reboot:
374 unregister_reboot_notifier(&wdt_notifier);
375 err_out_region2:
376 if (wdt_stop != 0x45 && wdt_stop != wdt_start)
377 release_region(wdt_stop, 1);
378 err_out_region1:
379 release_region(wdt_start, 1);
380 err_out:
381 return rc;
382 }
383
384 module_init(sbc60xxwdt_init);
385 module_exit(sbc60xxwdt_unload);
386
387 MODULE_AUTHOR("Jakob Oestergaard <jakob@unthought.net>");
388 MODULE_DESCRIPTION("60xx Single Board Computer Watchdog Timer driver");
389 MODULE_LICENSE("GPL");
390