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 	.write		= fop_write,
279 	.open		= fop_open,
280 	.release	= fop_close,
281 	.unlocked_ioctl	= fop_ioctl,
282 	.compat_ioctl	= compat_ptr_ioctl,
283 };
284 
285 static struct miscdevice wdt_miscdev = {
286 	.minor = WATCHDOG_MINOR,
287 	.name = "watchdog",
288 	.fops = &wdt_fops,
289 };
290 
291 /*
292  *	Notifier for system down
293  */
294 
wdt_notify_sys(struct notifier_block * this,unsigned long code,void * unused)295 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
296 	void *unused)
297 {
298 	if (code == SYS_DOWN || code == SYS_HALT)
299 		wdt_turnoff();
300 	return NOTIFY_DONE;
301 }
302 
303 /*
304  *	The WDT needs to learn about soft shutdowns in order to
305  *	turn the timebomb registers off.
306  */
307 
308 static struct notifier_block wdt_notifier = {
309 	.notifier_call = wdt_notify_sys,
310 };
311 
sbc60xxwdt_unload(void)312 static void __exit sbc60xxwdt_unload(void)
313 {
314 	wdt_turnoff();
315 
316 	/* Deregister */
317 	misc_deregister(&wdt_miscdev);
318 
319 	unregister_reboot_notifier(&wdt_notifier);
320 	if ((wdt_stop != 0x45) && (wdt_stop != wdt_start))
321 		release_region(wdt_stop, 1);
322 	release_region(wdt_start, 1);
323 }
324 
sbc60xxwdt_init(void)325 static int __init sbc60xxwdt_init(void)
326 {
327 	int rc = -EBUSY;
328 
329 	if (timeout < 1 || timeout > 3600) { /* arbitrary upper limit */
330 		timeout = WATCHDOG_TIMEOUT;
331 		pr_info("timeout value must be 1 <= x <= 3600, using %d\n",
332 			timeout);
333 	}
334 
335 	if (!request_region(wdt_start, 1, "SBC 60XX WDT")) {
336 		pr_err("I/O address 0x%04x already in use\n", wdt_start);
337 		rc = -EIO;
338 		goto err_out;
339 	}
340 
341 	/* We cannot reserve 0x45 - the kernel already has! */
342 	if (wdt_stop != 0x45 && wdt_stop != wdt_start) {
343 		if (!request_region(wdt_stop, 1, "SBC 60XX WDT")) {
344 			pr_err("I/O address 0x%04x already in use\n", wdt_stop);
345 			rc = -EIO;
346 			goto err_out_region1;
347 		}
348 	}
349 
350 	rc = register_reboot_notifier(&wdt_notifier);
351 	if (rc) {
352 		pr_err("cannot register reboot notifier (err=%d)\n", rc);
353 		goto err_out_region2;
354 	}
355 
356 	rc = misc_register(&wdt_miscdev);
357 	if (rc) {
358 		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
359 		       wdt_miscdev.minor, rc);
360 		goto err_out_reboot;
361 	}
362 	pr_info("WDT driver for 60XX single board computer initialised. timeout=%d sec (nowayout=%d)\n",
363 		timeout, nowayout);
364 
365 	return 0;
366 
367 err_out_reboot:
368 	unregister_reboot_notifier(&wdt_notifier);
369 err_out_region2:
370 	if (wdt_stop != 0x45 && wdt_stop != wdt_start)
371 		release_region(wdt_stop, 1);
372 err_out_region1:
373 	release_region(wdt_start, 1);
374 err_out:
375 	return rc;
376 }
377 
378 module_init(sbc60xxwdt_init);
379 module_exit(sbc60xxwdt_unload);
380 
381 MODULE_AUTHOR("Jakob Oestergaard <jakob@unthought.net>");
382 MODULE_DESCRIPTION("60xx Single Board Computer Watchdog Timer driver");
383 MODULE_LICENSE("GPL");
384