xref: /linux/drivers/watchdog/machzwd.c (revision 9a6b55ac) 
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *  MachZ ZF-Logic Watchdog Timer driver for Linux
4  *
5  *  The author does NOT admit liability nor provide warranty for
6  *  any of this software. This material is provided "AS-IS" in
7  *  the hope that it may be useful for others.
8  *
9  *  Author: Fernando Fuganti <fuganti@conectiva.com.br>
10  *
11  *  Based on sbc60xxwdt.c by Jakob Oestergaard
12  *
13  *  We have two timers (wd#1, wd#2) driven by a 32 KHz clock with the
14  *  following periods:
15  *      wd#1 - 2 seconds;
16  *      wd#2 - 7.2 ms;
17  *  After the expiration of wd#1, it can generate a NMI, SCI, SMI, or
18  *  a system RESET and it starts wd#2 that unconditionally will RESET
19  *  the system when the counter reaches zero.
20  *
21  *  14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
22  *      Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
23  */
24 
25 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
26 
27 #include <linux/module.h>
28 #include <linux/moduleparam.h>
29 #include <linux/types.h>
30 #include <linux/timer.h>
31 #include <linux/jiffies.h>
32 #include <linux/miscdevice.h>
33 #include <linux/watchdog.h>
34 #include <linux/fs.h>
35 #include <linux/ioport.h>
36 #include <linux/notifier.h>
37 #include <linux/reboot.h>
38 #include <linux/init.h>
39 #include <linux/io.h>
40 #include <linux/uaccess.h>
41 
42 
43 /* ports */
44 #define ZF_IOBASE	0x218
45 #define INDEX		0x218
46 #define DATA_B		0x219
47 #define DATA_W		0x21A
48 #define DATA_D		0x21A
49 
50 /* indexes */			/* size */
51 #define ZFL_VERSION	0x02	/* 16   */
52 #define CONTROL		0x10	/* 16   */
53 #define STATUS		0x12	/* 8    */
54 #define COUNTER_1	0x0C	/* 16   */
55 #define COUNTER_2	0x0E	/* 8    */
56 #define PULSE_LEN	0x0F	/* 8    */
57 
58 /* controls */
59 #define ENABLE_WD1	0x0001
60 #define ENABLE_WD2	0x0002
61 #define RESET_WD1	0x0010
62 #define RESET_WD2	0x0020
63 #define GEN_SCI		0x0100
64 #define GEN_NMI		0x0200
65 #define GEN_SMI		0x0400
66 #define GEN_RESET	0x0800
67 
68 
69 /* utilities */
70 
71 #define WD1	0
72 #define WD2	1
73 
74 #define zf_writew(port, data)  { outb(port, INDEX); outw(data, DATA_W); }
75 #define zf_writeb(port, data)  { outb(port, INDEX); outb(data, DATA_B); }
76 #define zf_get_ZFL_version()   zf_readw(ZFL_VERSION)
77 
78 
79 static unsigned short zf_readw(unsigned char port)
80 {
81 	outb(port, INDEX);
82 	return inw(DATA_W);
83 }
84 
85 
86 MODULE_AUTHOR("Fernando Fuganti <fuganti@conectiva.com.br>");
87 MODULE_DESCRIPTION("MachZ ZF-Logic Watchdog driver");
88 MODULE_LICENSE("GPL");
89 
90 static bool nowayout = WATCHDOG_NOWAYOUT;
91 module_param(nowayout, bool, 0);
92 MODULE_PARM_DESC(nowayout,
93 		"Watchdog cannot be stopped once started (default="
94 				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
95 
96 #define PFX "machzwd"
97 
98 static const struct watchdog_info zf_info = {
99 	.options		= WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
100 	.firmware_version	= 1,
101 	.identity		= "ZF-Logic watchdog",
102 };
103 
104 
105 /*
106  * action refers to action taken when watchdog resets
107  * 0 = GEN_RESET
108  * 1 = GEN_SMI
109  * 2 = GEN_NMI
110  * 3 = GEN_SCI
111  * defaults to GEN_RESET (0)
112  */
113 static int action;
114 module_param(action, int, 0);
115 MODULE_PARM_DESC(action, "after watchdog resets, generate: "
116 				"0 = RESET(*)  1 = SMI  2 = NMI  3 = SCI");
117 
118 static void zf_ping(struct timer_list *unused);
119 
120 static int zf_action = GEN_RESET;
121 static unsigned long zf_is_open;
122 static char zf_expect_close;
123 static DEFINE_SPINLOCK(zf_port_lock);
124 static DEFINE_TIMER(zf_timer, zf_ping);
125 static unsigned long next_heartbeat;
126 
127 
128 /* timeout for user land heart beat (10 seconds) */
129 #define ZF_USER_TIMEO (HZ*10)
130 
131 /* timeout for hardware watchdog (~500ms) */
132 #define ZF_HW_TIMEO (HZ/2)
133 
134 /* number of ticks on WD#1 (driven by a 32KHz clock, 2s) */
135 #define ZF_CTIMEOUT 0xffff
136 
137 #ifndef ZF_DEBUG
138 #define dprintk(format, args...)
139 #else
140 #define dprintk(format, args...)					\
141 	pr_debug(":%s:%d: " format, __func__, __LINE__ , ## args)
142 #endif
143 
144 
145 static inline void zf_set_status(unsigned char new)
146 {
147 	zf_writeb(STATUS, new);
148 }
149 
150 
151 /* CONTROL register functions */
152 
153 static inline unsigned short zf_get_control(void)
154 {
155 	return zf_readw(CONTROL);
156 }
157 
158 static inline void zf_set_control(unsigned short new)
159 {
160 	zf_writew(CONTROL, new);
161 }
162 
163 
164 /* WD#? counter functions */
165 /*
166  *	Just set counter value
167  */
168 
169 static inline void zf_set_timer(unsigned short new, unsigned char n)
170 {
171 	switch (n) {
172 	case WD1:
173 		zf_writew(COUNTER_1, new);
174 		/* fall through */
175 	case WD2:
176 		zf_writeb(COUNTER_2, new > 0xff ? 0xff : new);
177 	default:
178 		return;
179 	}
180 }
181 
182 /*
183  * stop hardware timer
184  */
185 static void zf_timer_off(void)
186 {
187 	unsigned int ctrl_reg = 0;
188 	unsigned long flags;
189 
190 	/* stop internal ping */
191 	del_timer_sync(&zf_timer);
192 
193 	spin_lock_irqsave(&zf_port_lock, flags);
194 	/* stop watchdog timer */
195 	ctrl_reg = zf_get_control();
196 	ctrl_reg |= (ENABLE_WD1|ENABLE_WD2);	/* disable wd1 and wd2 */
197 	ctrl_reg &= ~(ENABLE_WD1|ENABLE_WD2);
198 	zf_set_control(ctrl_reg);
199 	spin_unlock_irqrestore(&zf_port_lock, flags);
200 
201 	pr_info("Watchdog timer is now disabled\n");
202 }
203 
204 
205 /*
206  * start hardware timer
207  */
208 static void zf_timer_on(void)
209 {
210 	unsigned int ctrl_reg = 0;
211 	unsigned long flags;
212 
213 	spin_lock_irqsave(&zf_port_lock, flags);
214 
215 	zf_writeb(PULSE_LEN, 0xff);
216 
217 	zf_set_timer(ZF_CTIMEOUT, WD1);
218 
219 	/* user land ping */
220 	next_heartbeat = jiffies + ZF_USER_TIMEO;
221 
222 	/* start the timer for internal ping */
223 	mod_timer(&zf_timer, jiffies + ZF_HW_TIMEO);
224 
225 	/* start watchdog timer */
226 	ctrl_reg = zf_get_control();
227 	ctrl_reg |= (ENABLE_WD1|zf_action);
228 	zf_set_control(ctrl_reg);
229 	spin_unlock_irqrestore(&zf_port_lock, flags);
230 
231 	pr_info("Watchdog timer is now enabled\n");
232 }
233 
234 
235 static void zf_ping(struct timer_list *unused)
236 {
237 	unsigned int ctrl_reg = 0;
238 	unsigned long flags;
239 
240 	zf_writeb(COUNTER_2, 0xff);
241 
242 	if (time_before(jiffies, next_heartbeat)) {
243 		dprintk("time_before: %ld\n", next_heartbeat - jiffies);
244 		/*
245 		 * reset event is activated by transition from 0 to 1 on
246 		 * RESET_WD1 bit and we assume that it is already zero...
247 		 */
248 
249 		spin_lock_irqsave(&zf_port_lock, flags);
250 		ctrl_reg = zf_get_control();
251 		ctrl_reg |= RESET_WD1;
252 		zf_set_control(ctrl_reg);
253 
254 		/* ...and nothing changes until here */
255 		ctrl_reg &= ~(RESET_WD1);
256 		zf_set_control(ctrl_reg);
257 		spin_unlock_irqrestore(&zf_port_lock, flags);
258 
259 		mod_timer(&zf_timer, jiffies + ZF_HW_TIMEO);
260 	} else
261 		pr_crit("I will reset your machine\n");
262 }
263 
264 static ssize_t zf_write(struct file *file, const char __user *buf, size_t count,
265 								loff_t *ppos)
266 {
267 	/* See if we got the magic character */
268 	if (count) {
269 		/*
270 		 * no need to check for close confirmation
271 		 * no way to disable watchdog ;)
272 		 */
273 		if (!nowayout) {
274 			size_t ofs;
275 			/*
276 			 * note: just in case someone wrote the magic character
277 			 * five months ago...
278 			 */
279 			zf_expect_close = 0;
280 
281 			/* now scan */
282 			for (ofs = 0; ofs != count; ofs++) {
283 				char c;
284 				if (get_user(c, buf + ofs))
285 					return -EFAULT;
286 				if (c == 'V') {
287 					zf_expect_close = 42;
288 					dprintk("zf_expect_close = 42\n");
289 				}
290 			}
291 		}
292 
293 		/*
294 		 * Well, anyhow someone wrote to us,
295 		 * we should return that favour
296 		 */
297 		next_heartbeat = jiffies + ZF_USER_TIMEO;
298 		dprintk("user ping at %ld\n", jiffies);
299 	}
300 	return count;
301 }
302 
303 static long zf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
304 {
305 	void __user *argp = (void __user *)arg;
306 	int __user *p = argp;
307 	switch (cmd) {
308 	case WDIOC_GETSUPPORT:
309 		if (copy_to_user(argp, &zf_info, sizeof(zf_info)))
310 			return -EFAULT;
311 		break;
312 	case WDIOC_GETSTATUS:
313 	case WDIOC_GETBOOTSTATUS:
314 		return put_user(0, p);
315 	case WDIOC_KEEPALIVE:
316 		zf_ping(NULL);
317 		break;
318 	default:
319 		return -ENOTTY;
320 	}
321 	return 0;
322 }
323 
324 static int zf_open(struct inode *inode, struct file *file)
325 {
326 	if (test_and_set_bit(0, &zf_is_open))
327 		return -EBUSY;
328 	if (nowayout)
329 		__module_get(THIS_MODULE);
330 	zf_timer_on();
331 	return stream_open(inode, file);
332 }
333 
334 static int zf_close(struct inode *inode, struct file *file)
335 {
336 	if (zf_expect_close == 42)
337 		zf_timer_off();
338 	else {
339 		del_timer(&zf_timer);
340 		pr_err("device file closed unexpectedly. Will not stop the WDT!\n");
341 	}
342 	clear_bit(0, &zf_is_open);
343 	zf_expect_close = 0;
344 	return 0;
345 }
346 
347 /*
348  * Notifier for system down
349  */
350 
351 static int zf_notify_sys(struct notifier_block *this, unsigned long code,
352 								void *unused)
353 {
354 	if (code == SYS_DOWN || code == SYS_HALT)
355 		zf_timer_off();
356 	return NOTIFY_DONE;
357 }
358 
359 static const struct file_operations zf_fops = {
360 	.owner		= THIS_MODULE,
361 	.llseek		= no_llseek,
362 	.write		= zf_write,
363 	.unlocked_ioctl = zf_ioctl,
364 	.compat_ioctl	= compat_ptr_ioctl,
365 	.open		= zf_open,
366 	.release	= zf_close,
367 };
368 
369 static struct miscdevice zf_miscdev = {
370 	.minor = WATCHDOG_MINOR,
371 	.name = "watchdog",
372 	.fops = &zf_fops,
373 };
374 
375 
376 /*
377  * The device needs to learn about soft shutdowns in order to
378  * turn the timebomb registers off.
379  */
380 static struct notifier_block zf_notifier = {
381 	.notifier_call = zf_notify_sys,
382 };
383 
384 static void __init zf_show_action(int act)
385 {
386 	static const char * const str[] = { "RESET", "SMI", "NMI", "SCI" };
387 
388 	pr_info("Watchdog using action = %s\n", str[act]);
389 }
390 
391 static int __init zf_init(void)
392 {
393 	int ret;
394 
395 	pr_info("MachZ ZF-Logic Watchdog driver initializing\n");
396 
397 	ret = zf_get_ZFL_version();
398 	if (!ret || ret == 0xffff) {
399 		pr_warn("no ZF-Logic found\n");
400 		return -ENODEV;
401 	}
402 
403 	if (action <= 3 && action >= 0)
404 		zf_action = zf_action >> action;
405 	else
406 		action = 0;
407 
408 	zf_show_action(action);
409 
410 	if (!request_region(ZF_IOBASE, 3, "MachZ ZFL WDT")) {
411 		pr_err("cannot reserve I/O ports at %d\n", ZF_IOBASE);
412 		ret = -EBUSY;
413 		goto no_region;
414 	}
415 
416 	ret = register_reboot_notifier(&zf_notifier);
417 	if (ret) {
418 		pr_err("can't register reboot notifier (err=%d)\n", ret);
419 		goto no_reboot;
420 	}
421 
422 	ret = misc_register(&zf_miscdev);
423 	if (ret) {
424 		pr_err("can't misc_register on minor=%d\n", WATCHDOG_MINOR);
425 		goto no_misc;
426 	}
427 
428 	zf_set_status(0);
429 	zf_set_control(0);
430 
431 	return 0;
432 
433 no_misc:
434 	unregister_reboot_notifier(&zf_notifier);
435 no_reboot:
436 	release_region(ZF_IOBASE, 3);
437 no_region:
438 	return ret;
439 }
440 
441 
442 static void __exit zf_exit(void)
443 {
444 	zf_timer_off();
445 
446 	misc_deregister(&zf_miscdev);
447 	unregister_reboot_notifier(&zf_notifier);
448 	release_region(ZF_IOBASE, 3);
449 }
450 
451 module_init(zf_init);
452 module_exit(zf_exit);
453