1 /*
2  *  MachZ ZF-Logic Watchdog Timer driver for Linux
3  *
4  *
5  *  This program is free software; you can redistribute it and/or
6  *  modify it under the terms of the GNU General Public License
7  *  as published by the Free Software Foundation; either version
8  *  2 of the License, or (at your option) any later version.
9  *
10  *  The author does NOT admit liability nor provide warranty for
11  *  any of this software. This material is provided "AS-IS" in
12  *  the hope that it may be useful for others.
13  *
14  *  Author: Fernando Fuganti <fuganti@conectiva.com.br>
15  *
16  *  Based on sbc60xxwdt.c by Jakob Oestergaard
17  *
18  *
19  *  We have two timers (wd#1, wd#2) driven by a 32 KHz clock with the
20  *  following periods:
21  *      wd#1 - 2 seconds;
22  *      wd#2 - 7.2 ms;
23  *  After the expiration of wd#1, it can generate a NMI, SCI, SMI, or
24  *  a system RESET and it starts wd#2 that unconditionally will RESET
25  *  the system when the counter reaches zero.
26  *
27  *  14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
28  *      Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
29  */
30 
31 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
32 
33 #include <linux/module.h>
34 #include <linux/moduleparam.h>
35 #include <linux/types.h>
36 #include <linux/timer.h>
37 #include <linux/jiffies.h>
38 #include <linux/miscdevice.h>
39 #include <linux/watchdog.h>
40 #include <linux/fs.h>
41 #include <linux/ioport.h>
42 #include <linux/notifier.h>
43 #include <linux/reboot.h>
44 #include <linux/init.h>
45 #include <linux/io.h>
46 #include <linux/uaccess.h>
47 
48 
49 /* ports */
50 #define ZF_IOBASE	0x218
51 #define INDEX		0x218
52 #define DATA_B		0x219
53 #define DATA_W		0x21A
54 #define DATA_D		0x21A
55 
56 /* indexes */			/* size */
57 #define ZFL_VERSION	0x02	/* 16   */
58 #define CONTROL		0x10	/* 16   */
59 #define STATUS		0x12	/* 8    */
60 #define COUNTER_1	0x0C	/* 16   */
61 #define COUNTER_2	0x0E	/* 8    */
62 #define PULSE_LEN	0x0F	/* 8    */
63 
64 /* controls */
65 #define ENABLE_WD1	0x0001
66 #define ENABLE_WD2	0x0002
67 #define RESET_WD1	0x0010
68 #define RESET_WD2	0x0020
69 #define GEN_SCI		0x0100
70 #define GEN_NMI		0x0200
71 #define GEN_SMI		0x0400
72 #define GEN_RESET	0x0800
73 
74 
75 /* utilities */
76 
77 #define WD1	0
78 #define WD2	1
79 
80 #define zf_writew(port, data)  { outb(port, INDEX); outw(data, DATA_W); }
81 #define zf_writeb(port, data)  { outb(port, INDEX); outb(data, DATA_B); }
82 #define zf_get_ZFL_version()   zf_readw(ZFL_VERSION)
83 
84 
zf_readw(unsigned char port)85 static unsigned short zf_readw(unsigned char port)
86 {
87 	outb(port, INDEX);
88 	return inw(DATA_W);
89 }
90 
91 
92 MODULE_AUTHOR("Fernando Fuganti <fuganti@conectiva.com.br>");
93 MODULE_DESCRIPTION("MachZ ZF-Logic Watchdog driver");
94 MODULE_LICENSE("GPL");
95 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
96 
97 static bool nowayout = WATCHDOG_NOWAYOUT;
98 module_param(nowayout, bool, 0);
99 MODULE_PARM_DESC(nowayout,
100 		"Watchdog cannot be stopped once started (default="
101 				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
102 
103 #define PFX "machzwd"
104 
105 static const struct watchdog_info zf_info = {
106 	.options		= WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
107 	.firmware_version	= 1,
108 	.identity		= "ZF-Logic watchdog",
109 };
110 
111 
112 /*
113  * action refers to action taken when watchdog resets
114  * 0 = GEN_RESET
115  * 1 = GEN_SMI
116  * 2 = GEN_NMI
117  * 3 = GEN_SCI
118  * defaults to GEN_RESET (0)
119  */
120 static int action;
121 module_param(action, int, 0);
122 MODULE_PARM_DESC(action, "after watchdog resets, generate: "
123 				"0 = RESET(*)  1 = SMI  2 = NMI  3 = SCI");
124 
125 static void zf_ping(unsigned long data);
126 
127 static int zf_action = GEN_RESET;
128 static unsigned long zf_is_open;
129 static char zf_expect_close;
130 static DEFINE_SPINLOCK(zf_port_lock);
131 static DEFINE_TIMER(zf_timer, zf_ping, 0, 0);
132 static unsigned long next_heartbeat;
133 
134 
135 /* timeout for user land heart beat (10 seconds) */
136 #define ZF_USER_TIMEO (HZ*10)
137 
138 /* timeout for hardware watchdog (~500ms) */
139 #define ZF_HW_TIMEO (HZ/2)
140 
141 /* number of ticks on WD#1 (driven by a 32KHz clock, 2s) */
142 #define ZF_CTIMEOUT 0xffff
143 
144 #ifndef ZF_DEBUG
145 #define dprintk(format, args...)
146 #else
147 #define dprintk(format, args...)					\
148 	pr_debug(":%s:%d: " format, __func__, __LINE__ , ## args)
149 #endif
150 
151 
zf_set_status(unsigned char new)152 static inline void zf_set_status(unsigned char new)
153 {
154 	zf_writeb(STATUS, new);
155 }
156 
157 
158 /* CONTROL register functions */
159 
zf_get_control(void)160 static inline unsigned short zf_get_control(void)
161 {
162 	return zf_readw(CONTROL);
163 }
164 
zf_set_control(unsigned short new)165 static inline void zf_set_control(unsigned short new)
166 {
167 	zf_writew(CONTROL, new);
168 }
169 
170 
171 /* WD#? counter functions */
172 /*
173  *	Just set counter value
174  */
175 
zf_set_timer(unsigned short new,unsigned char n)176 static inline void zf_set_timer(unsigned short new, unsigned char n)
177 {
178 	switch (n) {
179 	case WD1:
180 		zf_writew(COUNTER_1, new);
181 	case WD2:
182 		zf_writeb(COUNTER_2, new > 0xff ? 0xff : new);
183 	default:
184 		return;
185 	}
186 }
187 
188 /*
189  * stop hardware timer
190  */
zf_timer_off(void)191 static void zf_timer_off(void)
192 {
193 	unsigned int ctrl_reg = 0;
194 	unsigned long flags;
195 
196 	/* stop internal ping */
197 	del_timer_sync(&zf_timer);
198 
199 	spin_lock_irqsave(&zf_port_lock, flags);
200 	/* stop watchdog timer */
201 	ctrl_reg = zf_get_control();
202 	ctrl_reg |= (ENABLE_WD1|ENABLE_WD2);	/* disable wd1 and wd2 */
203 	ctrl_reg &= ~(ENABLE_WD1|ENABLE_WD2);
204 	zf_set_control(ctrl_reg);
205 	spin_unlock_irqrestore(&zf_port_lock, flags);
206 
207 	pr_info("Watchdog timer is now disabled\n");
208 }
209 
210 
211 /*
212  * start hardware timer
213  */
zf_timer_on(void)214 static void zf_timer_on(void)
215 {
216 	unsigned int ctrl_reg = 0;
217 	unsigned long flags;
218 
219 	spin_lock_irqsave(&zf_port_lock, flags);
220 
221 	zf_writeb(PULSE_LEN, 0xff);
222 
223 	zf_set_timer(ZF_CTIMEOUT, WD1);
224 
225 	/* user land ping */
226 	next_heartbeat = jiffies + ZF_USER_TIMEO;
227 
228 	/* start the timer for internal ping */
229 	mod_timer(&zf_timer, jiffies + ZF_HW_TIMEO);
230 
231 	/* start watchdog timer */
232 	ctrl_reg = zf_get_control();
233 	ctrl_reg |= (ENABLE_WD1|zf_action);
234 	zf_set_control(ctrl_reg);
235 	spin_unlock_irqrestore(&zf_port_lock, flags);
236 
237 	pr_info("Watchdog timer is now enabled\n");
238 }
239 
240 
zf_ping(unsigned long data)241 static void zf_ping(unsigned long data)
242 {
243 	unsigned int ctrl_reg = 0;
244 	unsigned long flags;
245 
246 	zf_writeb(COUNTER_2, 0xff);
247 
248 	if (time_before(jiffies, next_heartbeat)) {
249 		dprintk("time_before: %ld\n", next_heartbeat - jiffies);
250 		/*
251 		 * reset event is activated by transition from 0 to 1 on
252 		 * RESET_WD1 bit and we assume that it is already zero...
253 		 */
254 
255 		spin_lock_irqsave(&zf_port_lock, flags);
256 		ctrl_reg = zf_get_control();
257 		ctrl_reg |= RESET_WD1;
258 		zf_set_control(ctrl_reg);
259 
260 		/* ...and nothing changes until here */
261 		ctrl_reg &= ~(RESET_WD1);
262 		zf_set_control(ctrl_reg);
263 		spin_unlock_irqrestore(&zf_port_lock, flags);
264 
265 		mod_timer(&zf_timer, jiffies + ZF_HW_TIMEO);
266 	} else
267 		pr_crit("I will reset your machine\n");
268 }
269 
zf_write(struct file * file,const char __user * buf,size_t count,loff_t * ppos)270 static ssize_t zf_write(struct file *file, const char __user *buf, size_t count,
271 								loff_t *ppos)
272 {
273 	/* See if we got the magic character */
274 	if (count) {
275 		/*
276 		 * no need to check for close confirmation
277 		 * no way to disable watchdog ;)
278 		 */
279 		if (!nowayout) {
280 			size_t ofs;
281 			/*
282 			 * note: just in case someone wrote the magic character
283 			 * five months ago...
284 			 */
285 			zf_expect_close = 0;
286 
287 			/* now scan */
288 			for (ofs = 0; ofs != count; ofs++) {
289 				char c;
290 				if (get_user(c, buf + ofs))
291 					return -EFAULT;
292 				if (c == 'V') {
293 					zf_expect_close = 42;
294 					dprintk("zf_expect_close = 42\n");
295 				}
296 			}
297 		}
298 
299 		/*
300 		 * Well, anyhow someone wrote to us,
301 		 * we should return that favour
302 		 */
303 		next_heartbeat = jiffies + ZF_USER_TIMEO;
304 		dprintk("user ping at %ld\n", jiffies);
305 	}
306 	return count;
307 }
308 
zf_ioctl(struct file * file,unsigned int cmd,unsigned long arg)309 static long zf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
310 {
311 	void __user *argp = (void __user *)arg;
312 	int __user *p = argp;
313 	switch (cmd) {
314 	case WDIOC_GETSUPPORT:
315 		if (copy_to_user(argp, &zf_info, sizeof(zf_info)))
316 			return -EFAULT;
317 		break;
318 	case WDIOC_GETSTATUS:
319 	case WDIOC_GETBOOTSTATUS:
320 		return put_user(0, p);
321 	case WDIOC_KEEPALIVE:
322 		zf_ping(0);
323 		break;
324 	default:
325 		return -ENOTTY;
326 	}
327 	return 0;
328 }
329 
zf_open(struct inode * inode,struct file * file)330 static int zf_open(struct inode *inode, struct file *file)
331 {
332 	if (test_and_set_bit(0, &zf_is_open))
333 		return -EBUSY;
334 	if (nowayout)
335 		__module_get(THIS_MODULE);
336 	zf_timer_on();
337 	return nonseekable_open(inode, file);
338 }
339 
zf_close(struct inode * inode,struct file * file)340 static int zf_close(struct inode *inode, struct file *file)
341 {
342 	if (zf_expect_close == 42)
343 		zf_timer_off();
344 	else {
345 		del_timer(&zf_timer);
346 		pr_err("device file closed unexpectedly. Will not stop the WDT!\n");
347 	}
348 	clear_bit(0, &zf_is_open);
349 	zf_expect_close = 0;
350 	return 0;
351 }
352 
353 /*
354  * Notifier for system down
355  */
356 
zf_notify_sys(struct notifier_block * this,unsigned long code,void * unused)357 static int zf_notify_sys(struct notifier_block *this, unsigned long code,
358 								void *unused)
359 {
360 	if (code == SYS_DOWN || code == SYS_HALT)
361 		zf_timer_off();
362 	return NOTIFY_DONE;
363 }
364 
365 static const struct file_operations zf_fops = {
366 	.owner		= THIS_MODULE,
367 	.llseek		= no_llseek,
368 	.write		= zf_write,
369 	.unlocked_ioctl = zf_ioctl,
370 	.open		= zf_open,
371 	.release	= zf_close,
372 };
373 
374 static struct miscdevice zf_miscdev = {
375 	.minor = WATCHDOG_MINOR,
376 	.name = "watchdog",
377 	.fops = &zf_fops,
378 };
379 
380 
381 /*
382  * The device needs to learn about soft shutdowns in order to
383  * turn the timebomb registers off.
384  */
385 static struct notifier_block zf_notifier = {
386 	.notifier_call = zf_notify_sys,
387 };
388 
zf_show_action(int act)389 static void __init zf_show_action(int act)
390 {
391 	static const char * const str[] = { "RESET", "SMI", "NMI", "SCI" };
392 
393 	pr_info("Watchdog using action = %s\n", str[act]);
394 }
395 
zf_init(void)396 static int __init zf_init(void)
397 {
398 	int ret;
399 
400 	pr_info("MachZ ZF-Logic Watchdog driver initializing\n");
401 
402 	ret = zf_get_ZFL_version();
403 	if (!ret || ret == 0xffff) {
404 		pr_warn("no ZF-Logic found\n");
405 		return -ENODEV;
406 	}
407 
408 	if (action <= 3 && action >= 0)
409 		zf_action = zf_action >> action;
410 	else
411 		action = 0;
412 
413 	zf_show_action(action);
414 
415 	if (!request_region(ZF_IOBASE, 3, "MachZ ZFL WDT")) {
416 		pr_err("cannot reserve I/O ports at %d\n", ZF_IOBASE);
417 		ret = -EBUSY;
418 		goto no_region;
419 	}
420 
421 	ret = register_reboot_notifier(&zf_notifier);
422 	if (ret) {
423 		pr_err("can't register reboot notifier (err=%d)\n", ret);
424 		goto no_reboot;
425 	}
426 
427 	ret = misc_register(&zf_miscdev);
428 	if (ret) {
429 		pr_err("can't misc_register on minor=%d\n", WATCHDOG_MINOR);
430 		goto no_misc;
431 	}
432 
433 	zf_set_status(0);
434 	zf_set_control(0);
435 
436 	return 0;
437 
438 no_misc:
439 	unregister_reboot_notifier(&zf_notifier);
440 no_reboot:
441 	release_region(ZF_IOBASE, 3);
442 no_region:
443 	return ret;
444 }
445 
446 
zf_exit(void)447 static void __exit zf_exit(void)
448 {
449 	zf_timer_off();
450 
451 	misc_deregister(&zf_miscdev);
452 	unregister_reboot_notifier(&zf_notifier);
453 	release_region(ZF_IOBASE, 3);
454 }
455 
456 module_init(zf_init);
457 module_exit(zf_exit);
458