1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * 60xx Single Board Computer Watchdog Timer driver for Linux 2.2.x
4 *
5 * Based on acquirewdt.c by Alan Cox.
6 *
7 * The author does NOT admit liability nor provide warranty for
8 * any of this software. This material is provided "AS-IS" in
9 * the hope that it may be useful for others.
10 *
11 * (c) Copyright 2000 Jakob Oestergaard <jakob@unthought.net>
12 *
13 * 12/4 - 2000 [Initial revision]
14 * 25/4 - 2000 Added /dev/watchdog support
15 * 09/5 - 2001 [smj@oro.net] fixed fop_write to "return 1"
16 * on success
17 * 12/4 - 2002 [rob@osinvestor.com] eliminate fop_read
18 * fix possible wdt_is_open race
19 * add CONFIG_WATCHDOG_NOWAYOUT support
20 * remove lock_kernel/unlock_kernel pairs
21 * added KERN_* to printk's
22 * got rid of extraneous comments
23 * changed watchdog_info to correctly reflect what
24 * the driver offers
25 * added WDIOC_GETSTATUS, WDIOC_GETBOOTSTATUS,
26 * WDIOC_SETTIMEOUT, WDIOC_GETTIMEOUT, and
27 * WDIOC_SETOPTIONS ioctls
28 * 09/8 - 2003 [wim@iguana.be] cleanup of trailing spaces
29 * use module_param
30 * made timeout (the emulated heartbeat) a
31 * module_param
32 * made the keepalive ping an internal subroutine
33 * made wdt_stop and wdt_start module params
34 * added extra printk's for startup problems
35 * added MODULE_AUTHOR and MODULE_DESCRIPTION info
36 *
37 * This WDT driver is different from the other Linux WDT
38 * drivers in the following ways:
39 * *) The driver will ping the watchdog by itself, because this
40 * particular WDT has a very short timeout (one second) and it
41 * would be insane to count on any userspace daemon always
42 * getting scheduled within that time frame.
43 */
44
45 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
46
47 #include <linux/module.h>
48 #include <linux/moduleparam.h>
49 #include <linux/types.h>
50 #include <linux/timer.h>
51 #include <linux/jiffies.h>
52 #include <linux/miscdevice.h>
53 #include <linux/watchdog.h>
54 #include <linux/fs.h>
55 #include <linux/ioport.h>
56 #include <linux/notifier.h>
57 #include <linux/reboot.h>
58 #include <linux/init.h>
59 #include <linux/io.h>
60 #include <linux/uaccess.h>
61
62
63 #define OUR_NAME "sbc60xxwdt"
64 #define PFX OUR_NAME ": "
65
66 /*
67 * You must set these - The driver cannot probe for the settings
68 */
69
70 static int wdt_stop = 0x45;
71 module_param(wdt_stop, int, 0);
72 MODULE_PARM_DESC(wdt_stop, "SBC60xx WDT 'stop' io port (default 0x45)");
73
74 static int wdt_start = 0x443;
75 module_param(wdt_start, int, 0);
76 MODULE_PARM_DESC(wdt_start, "SBC60xx WDT 'start' io port (default 0x443)");
77
78 /*
79 * The 60xx board can use watchdog timeout values from one second
80 * to several minutes. The default is one second, so if we reset
81 * the watchdog every ~250ms we should be safe.
82 */
83
84 #define WDT_INTERVAL (HZ/4+1)
85
86 /*
87 * We must not require too good response from the userspace daemon.
88 * Here we require the userspace daemon to send us a heartbeat
89 * char to /dev/watchdog every 30 seconds.
90 * If the daemon pulses us every 25 seconds, we can still afford
91 * a 5 second scheduling delay on the (high priority) daemon. That
92 * should be sufficient for a box under any load.
93 */
94
95 #define WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */
96 static int timeout = WATCHDOG_TIMEOUT; /* in seconds, multiplied by HZ to
97 get seconds to wait for a ping */
98 module_param(timeout, int, 0);
99 MODULE_PARM_DESC(timeout,
100 "Watchdog timeout in seconds. (1<=timeout<=3600, default="
101 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
102
103 static bool nowayout = WATCHDOG_NOWAYOUT;
104 module_param(nowayout, bool, 0);
105 MODULE_PARM_DESC(nowayout,
106 "Watchdog cannot be stopped once started (default="
107 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
108
109 static void wdt_timer_ping(struct timer_list *);
110 static DEFINE_TIMER(timer, wdt_timer_ping);
111 static unsigned long next_heartbeat;
112 static unsigned long wdt_is_open;
113 static char wdt_expect_close;
114
115 /*
116 * Whack the dog
117 */
118
wdt_timer_ping(struct timer_list * unused)119 static void wdt_timer_ping(struct timer_list *unused)
120 {
121 /* If we got a heartbeat pulse within the WDT_US_INTERVAL
122 * we agree to ping the WDT
123 */
124 if (time_before(jiffies, next_heartbeat)) {
125 /* Ping the WDT by reading from wdt_start */
126 inb_p(wdt_start);
127 /* Re-set the timer interval */
128 mod_timer(&timer, jiffies + WDT_INTERVAL);
129 } else
130 pr_warn("Heartbeat lost! Will not ping the watchdog\n");
131 }
132
133 /*
134 * Utility routines
135 */
136
wdt_startup(void)137 static void wdt_startup(void)
138 {
139 next_heartbeat = jiffies + (timeout * HZ);
140
141 /* Start the timer */
142 mod_timer(&timer, jiffies + WDT_INTERVAL);
143 pr_info("Watchdog timer is now enabled\n");
144 }
145
wdt_turnoff(void)146 static void wdt_turnoff(void)
147 {
148 /* Stop the timer */
149 del_timer_sync(&timer);
150 inb_p(wdt_stop);
151 pr_info("Watchdog timer is now disabled...\n");
152 }
153
wdt_keepalive(void)154 static void wdt_keepalive(void)
155 {
156 /* user land ping */
157 next_heartbeat = jiffies + (timeout * HZ);
158 }
159
160 /*
161 * /dev/watchdog handling
162 */
163
fop_write(struct file * file,const char __user * buf,size_t count,loff_t * ppos)164 static ssize_t fop_write(struct file *file, const char __user *buf,
165 size_t count, loff_t *ppos)
166 {
167 /* See if we got the magic character 'V' and reload the timer */
168 if (count) {
169 if (!nowayout) {
170 size_t ofs;
171
172 /* note: just in case someone wrote the
173 magic character five months ago... */
174 wdt_expect_close = 0;
175
176 /* scan to see whether or not we got the
177 magic character */
178 for (ofs = 0; ofs != count; ofs++) {
179 char c;
180 if (get_user(c, buf + ofs))
181 return -EFAULT;
182 if (c == 'V')
183 wdt_expect_close = 42;
184 }
185 }
186
187 /* Well, anyhow someone wrote to us, we should
188 return that favour */
189 wdt_keepalive();
190 }
191 return count;
192 }
193
fop_open(struct inode * inode,struct file * file)194 static int fop_open(struct inode *inode, struct file *file)
195 {
196 /* Just in case we're already talking to someone... */
197 if (test_and_set_bit(0, &wdt_is_open))
198 return -EBUSY;
199
200 if (nowayout)
201 __module_get(THIS_MODULE);
202
203 /* Good, fire up the show */
204 wdt_startup();
205 return stream_open(inode, file);
206 }
207
fop_close(struct inode * inode,struct file * file)208 static int fop_close(struct inode *inode, struct file *file)
209 {
210 if (wdt_expect_close == 42)
211 wdt_turnoff();
212 else {
213 del_timer(&timer);
214 pr_crit("device file closed unexpectedly. Will not stop the WDT!\n");
215 }
216 clear_bit(0, &wdt_is_open);
217 wdt_expect_close = 0;
218 return 0;
219 }
220
fop_ioctl(struct file * file,unsigned int cmd,unsigned long arg)221 static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
222 {
223 void __user *argp = (void __user *)arg;
224 int __user *p = argp;
225 static const struct watchdog_info ident = {
226 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
227 WDIOF_MAGICCLOSE,
228 .firmware_version = 1,
229 .identity = "SBC60xx",
230 };
231
232 switch (cmd) {
233 case WDIOC_GETSUPPORT:
234 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
235 case WDIOC_GETSTATUS:
236 case WDIOC_GETBOOTSTATUS:
237 return put_user(0, p);
238 case WDIOC_SETOPTIONS:
239 {
240 int new_options, retval = -EINVAL;
241 if (get_user(new_options, p))
242 return -EFAULT;
243 if (new_options & WDIOS_DISABLECARD) {
244 wdt_turnoff();
245 retval = 0;
246 }
247 if (new_options & WDIOS_ENABLECARD) {
248 wdt_startup();
249 retval = 0;
250 }
251 return retval;
252 }
253 case WDIOC_KEEPALIVE:
254 wdt_keepalive();
255 return 0;
256 case WDIOC_SETTIMEOUT:
257 {
258 int new_timeout;
259 if (get_user(new_timeout, p))
260 return -EFAULT;
261 /* arbitrary upper limit */
262 if (new_timeout < 1 || new_timeout > 3600)
263 return -EINVAL;
264
265 timeout = new_timeout;
266 wdt_keepalive();
267 }
268 fallthrough;
269 case WDIOC_GETTIMEOUT:
270 return put_user(timeout, p);
271 default:
272 return -ENOTTY;
273 }
274 }
275
276 static const struct file_operations wdt_fops = {
277 .owner = THIS_MODULE,
278 .llseek = no_llseek,
279 .write = fop_write,
280 .open = fop_open,
281 .release = fop_close,
282 .unlocked_ioctl = fop_ioctl,
283 .compat_ioctl = compat_ptr_ioctl,
284 };
285
286 static struct miscdevice wdt_miscdev = {
287 .minor = WATCHDOG_MINOR,
288 .name = "watchdog",
289 .fops = &wdt_fops,
290 };
291
292 /*
293 * Notifier for system down
294 */
295
wdt_notify_sys(struct notifier_block * this,unsigned long code,void * unused)296 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
297 void *unused)
298 {
299 if (code == SYS_DOWN || code == SYS_HALT)
300 wdt_turnoff();
301 return NOTIFY_DONE;
302 }
303
304 /*
305 * The WDT needs to learn about soft shutdowns in order to
306 * turn the timebomb registers off.
307 */
308
309 static struct notifier_block wdt_notifier = {
310 .notifier_call = wdt_notify_sys,
311 };
312
sbc60xxwdt_unload(void)313 static void __exit sbc60xxwdt_unload(void)
314 {
315 wdt_turnoff();
316
317 /* Deregister */
318 misc_deregister(&wdt_miscdev);
319
320 unregister_reboot_notifier(&wdt_notifier);
321 if ((wdt_stop != 0x45) && (wdt_stop != wdt_start))
322 release_region(wdt_stop, 1);
323 release_region(wdt_start, 1);
324 }
325
sbc60xxwdt_init(void)326 static int __init sbc60xxwdt_init(void)
327 {
328 int rc = -EBUSY;
329
330 if (timeout < 1 || timeout > 3600) { /* arbitrary upper limit */
331 timeout = WATCHDOG_TIMEOUT;
332 pr_info("timeout value must be 1 <= x <= 3600, using %d\n",
333 timeout);
334 }
335
336 if (!request_region(wdt_start, 1, "SBC 60XX WDT")) {
337 pr_err("I/O address 0x%04x already in use\n", wdt_start);
338 rc = -EIO;
339 goto err_out;
340 }
341
342 /* We cannot reserve 0x45 - the kernel already has! */
343 if (wdt_stop != 0x45 && wdt_stop != wdt_start) {
344 if (!request_region(wdt_stop, 1, "SBC 60XX WDT")) {
345 pr_err("I/O address 0x%04x already in use\n", wdt_stop);
346 rc = -EIO;
347 goto err_out_region1;
348 }
349 }
350
351 rc = register_reboot_notifier(&wdt_notifier);
352 if (rc) {
353 pr_err("cannot register reboot notifier (err=%d)\n", rc);
354 goto err_out_region2;
355 }
356
357 rc = misc_register(&wdt_miscdev);
358 if (rc) {
359 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
360 wdt_miscdev.minor, rc);
361 goto err_out_reboot;
362 }
363 pr_info("WDT driver for 60XX single board computer initialised. timeout=%d sec (nowayout=%d)\n",
364 timeout, nowayout);
365
366 return 0;
367
368 err_out_reboot:
369 unregister_reboot_notifier(&wdt_notifier);
370 err_out_region2:
371 if (wdt_stop != 0x45 && wdt_stop != wdt_start)
372 release_region(wdt_stop, 1);
373 err_out_region1:
374 release_region(wdt_start, 1);
375 err_out:
376 return rc;
377 }
378
379 module_init(sbc60xxwdt_init);
380 module_exit(sbc60xxwdt_unload);
381
382 MODULE_AUTHOR("Jakob Oestergaard <jakob@unthought.net>");
383 MODULE_DESCRIPTION("60xx Single Board Computer Watchdog Timer driver");
384 MODULE_LICENSE("GPL");
385