1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  *	SBC8360 Watchdog driver
4  *
5  *	(c) Copyright 2005 Webcon, Inc.
6  *
7  *	Based on ib700wdt.c, which is based on advantechwdt.c which is based
8  *	on acquirewdt.c which is based on wdt.c.
9  *
10  *	(c) Copyright 2001 Charles Howes <chowes@vsol.net>
11  *
12  *	Based on advantechwdt.c which is based on acquirewdt.c which
13  *	is based on wdt.c.
14  *
15  *	(c) Copyright 2000-2001 Marek Michalkiewicz <marekm@linux.org.pl>
16  *
17  *	Based on acquirewdt.c which is based on wdt.c.
18  *	Original copyright messages:
19  *
20  *	(c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
21  *						All Rights Reserved.
22  *
23  *	Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
24  *	warranty for any of this software. This material is provided
25  *	"AS-IS" and at no charge.
26  *
27  *	(c) Copyright 1995    Alan Cox <alan@lxorguk.ukuu.org.uk>
28  *
29  *	14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
30  *	     Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
31  *	     Added timeout module option to override default
32  *
33  */
34 
35 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
36 
37 #include <linux/module.h>
38 #include <linux/types.h>
39 #include <linux/miscdevice.h>
40 #include <linux/watchdog.h>
41 #include <linux/ioport.h>
42 #include <linux/delay.h>
43 #include <linux/notifier.h>
44 #include <linux/fs.h>
45 #include <linux/reboot.h>
46 #include <linux/init.h>
47 #include <linux/spinlock.h>
48 #include <linux/moduleparam.h>
49 #include <linux/io.h>
50 #include <linux/uaccess.h>
51 
52 
53 static unsigned long sbc8360_is_open;
54 static char expect_close;
55 
56 /*
57  *
58  * Watchdog Timer Configuration
59  *
60  * The function of the watchdog timer is to reset the system automatically
61  * and is defined at I/O port 0120H and 0121H.  To enable the watchdog timer
62  * and allow the system to reset, write appropriate values from the table
63  * below to I/O port 0120H and 0121H.  To disable the timer, write a zero
64  * value to I/O port 0121H for the system to stop the watchdog function.
65  *
66  * The following describes how the timer should be programmed (according to
67  * the vendor documentation)
68  *
69  * Enabling Watchdog:
70  * MOV AX,000AH (enable, phase I)
71  * MOV DX,0120H
72  * OUT DX,AX
73  * MOV AX,000BH (enable, phase II)
74  * MOV DX,0120H
75  * OUT DX,AX
76  * MOV AX,000nH (set multiplier n, from 1-4)
77  * MOV DX,0120H
78  * OUT DX,AX
79  * MOV AX,000mH (set base timer m, from 0-F)
80  * MOV DX,0121H
81  * OUT DX,AX
82  *
83  * Reset timer:
84  * MOV AX,000mH (same as set base timer, above)
85  * MOV DX,0121H
86  * OUT DX,AX
87  *
88  * Disabling Watchdog:
89  * MOV AX,0000H (a zero value)
90  * MOV DX,0120H
91  * OUT DX,AX
92  *
93  * Watchdog timeout configuration values:
94  *		N
95  *	M |	1	2	3	4
96  *	--|----------------------------------
97  *	0 |	0.5s	5s	50s	100s
98  *	1 |	1s	10s	100s	200s
99  *	2 |	1.5s	15s	150s	300s
100  *	3 |	2s	20s	200s	400s
101  *	4 |	2.5s	25s	250s	500s
102  *	5 |	3s	30s	300s	600s
103  *	6 |	3.5s	35s	350s	700s
104  *	7 |	4s	40s	400s	800s
105  *	8 |	4.5s	45s	450s	900s
106  *	9 |	5s	50s	500s	1000s
107  *	A |	5.5s	55s	550s	1100s
108  *	B |	6s	60s	600s	1200s
109  *	C |	6.5s	65s	650s	1300s
110  *	D |	7s	70s	700s	1400s
111  *	E |	7.5s	75s	750s	1500s
112  *	F |	8s	80s	800s	1600s
113  *
114  * Another way to say the same things is:
115  *  For N=1, Timeout = (M+1) * 0.5s
116  *  For N=2, Timeout = (M+1) * 5s
117  *  For N=3, Timeout = (M+1) * 50s
118  *  For N=4, Timeout = (M+1) * 100s
119  *
120  */
121 
122 static int wd_times[64][2] = {
123 	{0, 1},			/* 0  = 0.5s */
124 	{1, 1},			/* 1  = 1s   */
125 	{2, 1},			/* 2  = 1.5s */
126 	{3, 1},			/* 3  = 2s   */
127 	{4, 1},			/* 4  = 2.5s */
128 	{5, 1},			/* 5  = 3s   */
129 	{6, 1},			/* 6  = 3.5s */
130 	{7, 1},			/* 7  = 4s   */
131 	{8, 1},			/* 8  = 4.5s */
132 	{9, 1},			/* 9  = 5s   */
133 	{0xA, 1},		/* 10 = 5.5s */
134 	{0xB, 1},		/* 11 = 6s   */
135 	{0xC, 1},		/* 12 = 6.5s */
136 	{0xD, 1},		/* 13 = 7s   */
137 	{0xE, 1},		/* 14 = 7.5s */
138 	{0xF, 1},		/* 15 = 8s   */
139 	{0, 2},			/* 16 = 5s  */
140 	{1, 2},			/* 17 = 10s */
141 	{2, 2},			/* 18 = 15s */
142 	{3, 2},			/* 19 = 20s */
143 	{4, 2},			/* 20 = 25s */
144 	{5, 2},			/* 21 = 30s */
145 	{6, 2},			/* 22 = 35s */
146 	{7, 2},			/* 23 = 40s */
147 	{8, 2},			/* 24 = 45s */
148 	{9, 2},			/* 25 = 50s */
149 	{0xA, 2},		/* 26 = 55s */
150 	{0xB, 2},		/* 27 = 60s */
151 	{0xC, 2},		/* 28 = 65s */
152 	{0xD, 2},		/* 29 = 70s */
153 	{0xE, 2},		/* 30 = 75s */
154 	{0xF, 2},		/* 31 = 80s */
155 	{0, 3},			/* 32 = 50s  */
156 	{1, 3},			/* 33 = 100s */
157 	{2, 3},			/* 34 = 150s */
158 	{3, 3},			/* 35 = 200s */
159 	{4, 3},			/* 36 = 250s */
160 	{5, 3},			/* 37 = 300s */
161 	{6, 3},			/* 38 = 350s */
162 	{7, 3},			/* 39 = 400s */
163 	{8, 3},			/* 40 = 450s */
164 	{9, 3},			/* 41 = 500s */
165 	{0xA, 3},		/* 42 = 550s */
166 	{0xB, 3},		/* 43 = 600s */
167 	{0xC, 3},		/* 44 = 650s */
168 	{0xD, 3},		/* 45 = 700s */
169 	{0xE, 3},		/* 46 = 750s */
170 	{0xF, 3},		/* 47 = 800s */
171 	{0, 4},			/* 48 = 100s */
172 	{1, 4},			/* 49 = 200s */
173 	{2, 4},			/* 50 = 300s */
174 	{3, 4},			/* 51 = 400s */
175 	{4, 4},			/* 52 = 500s */
176 	{5, 4},			/* 53 = 600s */
177 	{6, 4},			/* 54 = 700s */
178 	{7, 4},			/* 55 = 800s */
179 	{8, 4},			/* 56 = 900s */
180 	{9, 4},			/* 57 = 1000s */
181 	{0xA, 4},		/* 58 = 1100s */
182 	{0xB, 4},		/* 59 = 1200s */
183 	{0xC, 4},		/* 60 = 1300s */
184 	{0xD, 4},		/* 61 = 1400s */
185 	{0xE, 4},		/* 62 = 1500s */
186 	{0xF, 4}		/* 63 = 1600s */
187 };
188 
189 #define SBC8360_ENABLE 0x120
190 #define SBC8360_BASETIME 0x121
191 
192 static int timeout = 27;
193 static int wd_margin = 0xB;
194 static int wd_multiplier = 2;
195 static bool nowayout = WATCHDOG_NOWAYOUT;
196 
197 module_param(timeout, int, 0);
198 MODULE_PARM_DESC(timeout, "Index into timeout table (0-63) (default=27 (60s))");
199 module_param(nowayout, bool, 0);
200 MODULE_PARM_DESC(nowayout,
201 		 "Watchdog cannot be stopped once started (default="
202 				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
203 
204 /*
205  *	Kernel methods.
206  */
207 
208 /* Activate and pre-configure watchdog */
sbc8360_activate(void)209 static void sbc8360_activate(void)
210 {
211 	/* Enable the watchdog */
212 	outb(0x0A, SBC8360_ENABLE);
213 	msleep_interruptible(100);
214 	outb(0x0B, SBC8360_ENABLE);
215 	msleep_interruptible(100);
216 	/* Set timeout multiplier */
217 	outb(wd_multiplier, SBC8360_ENABLE);
218 	msleep_interruptible(100);
219 	/* Nothing happens until first sbc8360_ping() */
220 }
221 
222 /* Kernel pings watchdog */
sbc8360_ping(void)223 static void sbc8360_ping(void)
224 {
225 	/* Write the base timer register */
226 	outb(wd_margin, SBC8360_BASETIME);
227 }
228 
229 /* stop watchdog */
sbc8360_stop(void)230 static void sbc8360_stop(void)
231 {
232 	/* De-activate the watchdog */
233 	outb(0, SBC8360_ENABLE);
234 }
235 
236 /* Userspace pings kernel driver, or requests clean close */
sbc8360_write(struct file * file,const char __user * buf,size_t count,loff_t * ppos)237 static ssize_t sbc8360_write(struct file *file, const char __user *buf,
238 			     size_t count, loff_t *ppos)
239 {
240 	if (count) {
241 		if (!nowayout) {
242 			size_t i;
243 
244 			/* In case it was set long ago */
245 			expect_close = 0;
246 
247 			for (i = 0; i != count; i++) {
248 				char c;
249 				if (get_user(c, buf + i))
250 					return -EFAULT;
251 				if (c == 'V')
252 					expect_close = 42;
253 			}
254 		}
255 		sbc8360_ping();
256 	}
257 	return count;
258 }
259 
sbc8360_open(struct inode * inode,struct file * file)260 static int sbc8360_open(struct inode *inode, struct file *file)
261 {
262 	if (test_and_set_bit(0, &sbc8360_is_open))
263 		return -EBUSY;
264 	if (nowayout)
265 		__module_get(THIS_MODULE);
266 
267 	/* Activate and ping once to start the countdown */
268 	sbc8360_activate();
269 	sbc8360_ping();
270 	return stream_open(inode, file);
271 }
272 
sbc8360_close(struct inode * inode,struct file * file)273 static int sbc8360_close(struct inode *inode, struct file *file)
274 {
275 	if (expect_close == 42)
276 		sbc8360_stop();
277 	else
278 		pr_crit("SBC8360 device closed unexpectedly.  SBC8360 will not stop!\n");
279 
280 	clear_bit(0, &sbc8360_is_open);
281 	expect_close = 0;
282 	return 0;
283 }
284 
285 /*
286  *	Notifier for system down
287  */
288 
sbc8360_notify_sys(struct notifier_block * this,unsigned long code,void * unused)289 static int sbc8360_notify_sys(struct notifier_block *this, unsigned long code,
290 			      void *unused)
291 {
292 	if (code == SYS_DOWN || code == SYS_HALT)
293 		sbc8360_stop();	/* Disable the SBC8360 Watchdog */
294 
295 	return NOTIFY_DONE;
296 }
297 
298 /*
299  *	Kernel Interfaces
300  */
301 
302 static const struct file_operations sbc8360_fops = {
303 	.owner = THIS_MODULE,
304 	.llseek = no_llseek,
305 	.write = sbc8360_write,
306 	.open = sbc8360_open,
307 	.release = sbc8360_close,
308 };
309 
310 static struct miscdevice sbc8360_miscdev = {
311 	.minor = WATCHDOG_MINOR,
312 	.name = "watchdog",
313 	.fops = &sbc8360_fops,
314 };
315 
316 /*
317  *	The SBC8360 needs to learn about soft shutdowns in order to
318  *	turn the timebomb registers off.
319  */
320 
321 static struct notifier_block sbc8360_notifier = {
322 	.notifier_call = sbc8360_notify_sys,
323 };
324 
sbc8360_init(void)325 static int __init sbc8360_init(void)
326 {
327 	int res;
328 	unsigned long int mseconds = 60000;
329 
330 	if (timeout < 0 || timeout > 63) {
331 		pr_err("Invalid timeout index (must be 0-63)\n");
332 		res = -EINVAL;
333 		goto out;
334 	}
335 
336 	if (!request_region(SBC8360_ENABLE, 1, "SBC8360")) {
337 		pr_err("ENABLE method I/O %X is not available\n",
338 		       SBC8360_ENABLE);
339 		res = -EIO;
340 		goto out;
341 	}
342 	if (!request_region(SBC8360_BASETIME, 1, "SBC8360")) {
343 		pr_err("BASETIME method I/O %X is not available\n",
344 		       SBC8360_BASETIME);
345 		res = -EIO;
346 		goto out_nobasetimereg;
347 	}
348 
349 	res = register_reboot_notifier(&sbc8360_notifier);
350 	if (res) {
351 		pr_err("Failed to register reboot notifier\n");
352 		goto out_noreboot;
353 	}
354 
355 	res = misc_register(&sbc8360_miscdev);
356 	if (res) {
357 		pr_err("failed to register misc device\n");
358 		goto out_nomisc;
359 	}
360 
361 	wd_margin = wd_times[timeout][0];
362 	wd_multiplier = wd_times[timeout][1];
363 
364 	if (wd_multiplier == 1)
365 		mseconds = (wd_margin + 1) * 500;
366 	else if (wd_multiplier == 2)
367 		mseconds = (wd_margin + 1) * 5000;
368 	else if (wd_multiplier == 3)
369 		mseconds = (wd_margin + 1) * 50000;
370 	else if (wd_multiplier == 4)
371 		mseconds = (wd_margin + 1) * 100000;
372 
373 	/* My kingdom for the ability to print "0.5 seconds" in the kernel! */
374 	pr_info("Timeout set at %ld ms\n", mseconds);
375 
376 	return 0;
377 
378 out_nomisc:
379 	unregister_reboot_notifier(&sbc8360_notifier);
380 out_noreboot:
381 	release_region(SBC8360_BASETIME, 1);
382 out_nobasetimereg:
383 	release_region(SBC8360_ENABLE, 1);
384 out:
385 	return res;
386 }
387 
sbc8360_exit(void)388 static void __exit sbc8360_exit(void)
389 {
390 	misc_deregister(&sbc8360_miscdev);
391 	unregister_reboot_notifier(&sbc8360_notifier);
392 	release_region(SBC8360_ENABLE, 1);
393 	release_region(SBC8360_BASETIME, 1);
394 }
395 
396 module_init(sbc8360_init);
397 module_exit(sbc8360_exit);
398 
399 MODULE_AUTHOR("Ian E. Morgan <imorgan@webcon.ca>");
400 MODULE_DESCRIPTION("SBC8360 watchdog driver");
401 MODULE_LICENSE("GPL");
402 MODULE_VERSION("1.01");
403 
404 /* end of sbc8360.c */
405