xref: /openbmc/linux/drivers/watchdog/wdt.c (revision 4700df05)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  *	Industrial Computer Source WDT501 driver
4  *
5  *	(c) Copyright 1996-1997 Alan Cox <alan@lxorguk.ukuu.org.uk>,
6  *						All Rights Reserved.
7  *
8  *	Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
9  *	warranty for any of this software. This material is provided
10  *	"AS-IS" and at no charge.
11  *
12  *	(c) Copyright 1995    Alan Cox <alan@lxorguk.ukuu.org.uk>
13  *
14  *	Release 0.10.
15  *
16  *	Fixes
17  *		Dave Gregorich	:	Modularisation and minor bugs
18  *		Alan Cox	:	Added the watchdog ioctl() stuff
19  *		Alan Cox	:	Fixed the reboot problem (as noted by
20  *					Matt Crocker).
21  *		Alan Cox	:	Added wdt= boot option
22  *		Alan Cox	:	Cleaned up copy/user stuff
23  *		Tim Hockin	:	Added insmod parameters, comment
24  *					cleanup, parameterized timeout
25  *		Tigran Aivazian	:	Restructured wdt_init() to handle
26  *					failures
27  *		Joel Becker	:	Added WDIOC_GET/SETTIMEOUT
28  *		Matt Domsch	:	Added nowayout module option
29  */
30 
31 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
32 
33 #include <linux/interrupt.h>
34 #include <linux/module.h>
35 #include <linux/moduleparam.h>
36 #include <linux/types.h>
37 #include <linux/miscdevice.h>
38 #include <linux/watchdog.h>
39 #include <linux/fs.h>
40 #include <linux/ioport.h>
41 #include <linux/notifier.h>
42 #include <linux/reboot.h>
43 #include <linux/init.h>
44 #include <linux/io.h>
45 #include <linux/uaccess.h>
46 
47 #include "wd501p.h"
48 
49 static unsigned long wdt_is_open;
50 static char expect_close;
51 
52 /*
53  *	Module parameters
54  */
55 
56 #define WD_TIMO 60			/* Default heartbeat = 60 seconds */
57 
58 static int heartbeat = WD_TIMO;
59 static int wd_heartbeat;
60 module_param(heartbeat, int, 0);
61 MODULE_PARM_DESC(heartbeat,
62 	"Watchdog heartbeat in seconds. (0 < heartbeat < 65536, default="
63 				__MODULE_STRING(WD_TIMO) ")");
64 
65 static bool nowayout = WATCHDOG_NOWAYOUT;
66 module_param(nowayout, bool, 0);
67 MODULE_PARM_DESC(nowayout,
68 	"Watchdog cannot be stopped once started (default="
69 				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
70 
71 /* You must set these - there is no sane way to probe for this board. */
72 static int io = 0x240;
73 static int irq = 11;
74 
75 static DEFINE_SPINLOCK(wdt_lock);
76 
77 module_param_hw(io, int, ioport, 0);
78 MODULE_PARM_DESC(io, "WDT io port (default=0x240)");
79 module_param_hw(irq, int, irq, 0);
80 MODULE_PARM_DESC(irq, "WDT irq (default=11)");
81 
82 /* Support for the Fan Tachometer on the WDT501-P */
83 static int tachometer;
84 module_param(tachometer, int, 0);
85 MODULE_PARM_DESC(tachometer,
86 		"WDT501-P Fan Tachometer support (0=disable, default=0)");
87 
88 static int type = 500;
89 module_param(type, int, 0);
90 MODULE_PARM_DESC(type,
91 		"WDT501-P Card type (500 or 501, default=500)");
92 
93 /*
94  *	Programming support
95  */
96 
wdt_ctr_mode(int ctr,int mode)97 static void wdt_ctr_mode(int ctr, int mode)
98 {
99 	ctr <<= 6;
100 	ctr |= 0x30;
101 	ctr |= (mode << 1);
102 	outb_p(ctr, WDT_CR);
103 }
104 
wdt_ctr_load(int ctr,int val)105 static void wdt_ctr_load(int ctr, int val)
106 {
107 	outb_p(val&0xFF, WDT_COUNT0+ctr);
108 	outb_p(val>>8, WDT_COUNT0+ctr);
109 }
110 
111 /**
112  *	wdt_start:
113  *
114  *	Start the watchdog driver.
115  */
116 
wdt_start(void)117 static int wdt_start(void)
118 {
119 	unsigned long flags;
120 	spin_lock_irqsave(&wdt_lock, flags);
121 	inb_p(WDT_DC);			/* Disable watchdog */
122 	wdt_ctr_mode(0, 3);		/* Program CTR0 for Mode 3:
123 						Square Wave Generator */
124 	wdt_ctr_mode(1, 2);		/* Program CTR1 for Mode 2:
125 						Rate Generator */
126 	wdt_ctr_mode(2, 0);		/* Program CTR2 for Mode 0:
127 						Pulse on Terminal Count */
128 	wdt_ctr_load(0, 8948);		/* Count at 100Hz */
129 	wdt_ctr_load(1, wd_heartbeat);	/* Heartbeat */
130 	wdt_ctr_load(2, 65535);		/* Length of reset pulse */
131 	outb_p(0, WDT_DC);		/* Enable watchdog */
132 	spin_unlock_irqrestore(&wdt_lock, flags);
133 	return 0;
134 }
135 
136 /**
137  *	wdt_stop:
138  *
139  *	Stop the watchdog driver.
140  */
141 
wdt_stop(void)142 static int wdt_stop(void)
143 {
144 	unsigned long flags;
145 	spin_lock_irqsave(&wdt_lock, flags);
146 	/* Turn the card off */
147 	inb_p(WDT_DC);			/* Disable watchdog */
148 	wdt_ctr_load(2, 0);		/* 0 length reset pulses now */
149 	spin_unlock_irqrestore(&wdt_lock, flags);
150 	return 0;
151 }
152 
153 /**
154  *	wdt_ping:
155  *
156  *	Reload counter one with the watchdog heartbeat. We don't bother
157  *	reloading the cascade counter.
158  */
159 
wdt_ping(void)160 static void wdt_ping(void)
161 {
162 	unsigned long flags;
163 	spin_lock_irqsave(&wdt_lock, flags);
164 	/* Write a watchdog value */
165 	inb_p(WDT_DC);			/* Disable watchdog */
166 	wdt_ctr_mode(1, 2);		/* Re-Program CTR1 for Mode 2:
167 							Rate Generator */
168 	wdt_ctr_load(1, wd_heartbeat);	/* Heartbeat */
169 	outb_p(0, WDT_DC);		/* Enable watchdog */
170 	spin_unlock_irqrestore(&wdt_lock, flags);
171 }
172 
173 /**
174  *	wdt_set_heartbeat:
175  *	@t:		the new heartbeat value that needs to be set.
176  *
177  *	Set a new heartbeat value for the watchdog device. If the heartbeat
178  *	value is incorrect we keep the old value and return -EINVAL. If
179  *	successful we return 0.
180  */
181 
wdt_set_heartbeat(int t)182 static int wdt_set_heartbeat(int t)
183 {
184 	if (t < 1 || t > 65535)
185 		return -EINVAL;
186 
187 	heartbeat = t;
188 	wd_heartbeat = t * 100;
189 	return 0;
190 }
191 
192 /**
193  *	wdt_get_status:
194  *
195  *	Extract the status information from a WDT watchdog device. There are
196  *	several board variants so we have to know which bits are valid. Some
197  *	bits default to one and some to zero in order to be maximally painful.
198  *
199  *	we then map the bits onto the status ioctl flags.
200  */
201 
wdt_get_status(void)202 static int wdt_get_status(void)
203 {
204 	unsigned char new_status;
205 	int status = 0;
206 	unsigned long flags;
207 
208 	spin_lock_irqsave(&wdt_lock, flags);
209 	new_status = inb_p(WDT_SR);
210 	spin_unlock_irqrestore(&wdt_lock, flags);
211 
212 	if (new_status & WDC_SR_ISOI0)
213 		status |= WDIOF_EXTERN1;
214 	if (new_status & WDC_SR_ISII1)
215 		status |= WDIOF_EXTERN2;
216 	if (type == 501) {
217 		if (!(new_status & WDC_SR_TGOOD))
218 			status |= WDIOF_OVERHEAT;
219 		if (!(new_status & WDC_SR_PSUOVER))
220 			status |= WDIOF_POWEROVER;
221 		if (!(new_status & WDC_SR_PSUUNDR))
222 			status |= WDIOF_POWERUNDER;
223 		if (tachometer) {
224 			if (!(new_status & WDC_SR_FANGOOD))
225 				status |= WDIOF_FANFAULT;
226 		}
227 	}
228 	return status;
229 }
230 
231 /**
232  *	wdt_get_temperature:
233  *
234  *	Reports the temperature in degrees Fahrenheit. The API is in
235  *	farenheit. It was designed by an imperial measurement luddite.
236  */
237 
wdt_get_temperature(void)238 static int wdt_get_temperature(void)
239 {
240 	unsigned short c;
241 	unsigned long flags;
242 
243 	spin_lock_irqsave(&wdt_lock, flags);
244 	c = inb_p(WDT_RT);
245 	spin_unlock_irqrestore(&wdt_lock, flags);
246 	return (c * 11 / 15) + 7;
247 }
248 
wdt_decode_501(int status)249 static void wdt_decode_501(int status)
250 {
251 	if (!(status & WDC_SR_TGOOD))
252 		pr_crit("Overheat alarm (%d)\n", inb_p(WDT_RT));
253 	if (!(status & WDC_SR_PSUOVER))
254 		pr_crit("PSU over voltage\n");
255 	if (!(status & WDC_SR_PSUUNDR))
256 		pr_crit("PSU under voltage\n");
257 }
258 
259 /**
260  *	wdt_interrupt:
261  *	@irq:		Interrupt number
262  *	@dev_id:	Unused as we don't allow multiple devices.
263  *
264  *	Handle an interrupt from the board. These are raised when the status
265  *	map changes in what the board considers an interesting way. That means
266  *	a failure condition occurring.
267  */
268 
wdt_interrupt(int irq,void * dev_id)269 static irqreturn_t wdt_interrupt(int irq, void *dev_id)
270 {
271 	/*
272 	 *	Read the status register see what is up and
273 	 *	then printk it.
274 	 */
275 	unsigned char status;
276 
277 	spin_lock(&wdt_lock);
278 	status = inb_p(WDT_SR);
279 
280 	pr_crit("WDT status %d\n", status);
281 
282 	if (type == 501) {
283 		wdt_decode_501(status);
284 		if (tachometer) {
285 			if (!(status & WDC_SR_FANGOOD))
286 				pr_crit("Possible fan fault\n");
287 		}
288 	}
289 	if (!(status & WDC_SR_WCCR)) {
290 #ifdef SOFTWARE_REBOOT
291 #ifdef ONLY_TESTING
292 		pr_crit("Would Reboot\n");
293 #else
294 		pr_crit("Initiating system reboot\n");
295 		emergency_restart();
296 #endif
297 #else
298 		pr_crit("Reset in 5ms\n");
299 #endif
300 	}
301 	spin_unlock(&wdt_lock);
302 	return IRQ_HANDLED;
303 }
304 
305 
306 /**
307  *	wdt_write:
308  *	@file: file handle to the watchdog
309  *	@buf: buffer to write (unused as data does not matter here
310  *	@count: count of bytes
311  *	@ppos: pointer to the position to write. No seeks allowed
312  *
313  *	A write to a watchdog device is defined as a keepalive signal. Any
314  *	write of data will do, as we we don't define content meaning.
315  */
316 
wdt_write(struct file * file,const char __user * buf,size_t count,loff_t * ppos)317 static ssize_t wdt_write(struct file *file, const char __user *buf,
318 						size_t count, loff_t *ppos)
319 {
320 	if (count) {
321 		if (!nowayout) {
322 			size_t i;
323 
324 			/* In case it was set long ago */
325 			expect_close = 0;
326 
327 			for (i = 0; i != count; i++) {
328 				char c;
329 				if (get_user(c, buf + i))
330 					return -EFAULT;
331 				if (c == 'V')
332 					expect_close = 42;
333 			}
334 		}
335 		wdt_ping();
336 	}
337 	return count;
338 }
339 
340 /**
341  *	wdt_ioctl:
342  *	@file: file handle to the device
343  *	@cmd: watchdog command
344  *	@arg: argument pointer
345  *
346  *	The watchdog API defines a common set of functions for all watchdogs
347  *	according to their available features. We only actually usefully support
348  *	querying capabilities and current status.
349  */
350 
wdt_ioctl(struct file * file,unsigned int cmd,unsigned long arg)351 static long wdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
352 {
353 	void __user *argp = (void __user *)arg;
354 	int __user *p = argp;
355 	int new_heartbeat;
356 	int status;
357 
358 	struct watchdog_info ident = {
359 		.options =		WDIOF_SETTIMEOUT|
360 					WDIOF_MAGICCLOSE|
361 					WDIOF_KEEPALIVEPING,
362 		.firmware_version =	1,
363 		.identity =		"WDT500/501",
364 	};
365 
366 	/* Add options according to the card we have */
367 	ident.options |= (WDIOF_EXTERN1|WDIOF_EXTERN2);
368 	if (type == 501) {
369 		ident.options |= (WDIOF_OVERHEAT|WDIOF_POWERUNDER|
370 							WDIOF_POWEROVER);
371 		if (tachometer)
372 			ident.options |= WDIOF_FANFAULT;
373 	}
374 
375 	switch (cmd) {
376 	case WDIOC_GETSUPPORT:
377 		return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
378 	case WDIOC_GETSTATUS:
379 		status = wdt_get_status();
380 		return put_user(status, p);
381 	case WDIOC_GETBOOTSTATUS:
382 		return put_user(0, p);
383 	case WDIOC_KEEPALIVE:
384 		wdt_ping();
385 		return 0;
386 	case WDIOC_SETTIMEOUT:
387 		if (get_user(new_heartbeat, p))
388 			return -EFAULT;
389 		if (wdt_set_heartbeat(new_heartbeat))
390 			return -EINVAL;
391 		wdt_ping();
392 		fallthrough;
393 	case WDIOC_GETTIMEOUT:
394 		return put_user(heartbeat, p);
395 	default:
396 		return -ENOTTY;
397 	}
398 }
399 
400 /**
401  *	wdt_open:
402  *	@inode: inode of device
403  *	@file: file handle to device
404  *
405  *	The watchdog device has been opened. The watchdog device is single
406  *	open and on opening we load the counters. Counter zero is a 100Hz
407  *	cascade, into counter 1 which downcounts to reboot. When the counter
408  *	triggers counter 2 downcounts the length of the reset pulse which
409  *	set set to be as long as possible.
410  */
411 
wdt_open(struct inode * inode,struct file * file)412 static int wdt_open(struct inode *inode, struct file *file)
413 {
414 	if (test_and_set_bit(0, &wdt_is_open))
415 		return -EBUSY;
416 	/*
417 	 *	Activate
418 	 */
419 	wdt_start();
420 	return stream_open(inode, file);
421 }
422 
423 /**
424  *	wdt_release:
425  *	@inode: inode to board
426  *	@file: file handle to board
427  *
428  *	The watchdog has a configurable API. There is a religious dispute
429  *	between people who want their watchdog to be able to shut down and
430  *	those who want to be sure if the watchdog manager dies the machine
431  *	reboots. In the former case we disable the counters, in the latter
432  *	case you have to open it again very soon.
433  */
434 
wdt_release(struct inode * inode,struct file * file)435 static int wdt_release(struct inode *inode, struct file *file)
436 {
437 	if (expect_close == 42) {
438 		wdt_stop();
439 		clear_bit(0, &wdt_is_open);
440 	} else {
441 		pr_crit("WDT device closed unexpectedly.  WDT will not stop!\n");
442 		wdt_ping();
443 	}
444 	expect_close = 0;
445 	return 0;
446 }
447 
448 /**
449  *	wdt_temp_read:
450  *	@file: file handle to the watchdog board
451  *	@buf: buffer to write 1 byte into
452  *	@count: length of buffer
453  *	@ptr: offset (no seek allowed)
454  *
455  *	Temp_read reports the temperature in degrees Fahrenheit. The API is in
456  *	farenheit. It was designed by an imperial measurement luddite.
457  */
458 
wdt_temp_read(struct file * file,char __user * buf,size_t count,loff_t * ptr)459 static ssize_t wdt_temp_read(struct file *file, char __user *buf,
460 						size_t count, loff_t *ptr)
461 {
462 	int temperature = wdt_get_temperature();
463 
464 	if (copy_to_user(buf, &temperature, 1))
465 		return -EFAULT;
466 
467 	return 1;
468 }
469 
470 /**
471  *	wdt_temp_open:
472  *	@inode: inode of device
473  *	@file: file handle to device
474  *
475  *	The temperature device has been opened.
476  */
477 
wdt_temp_open(struct inode * inode,struct file * file)478 static int wdt_temp_open(struct inode *inode, struct file *file)
479 {
480 	return stream_open(inode, file);
481 }
482 
483 /**
484  *	wdt_temp_release:
485  *	@inode: inode to board
486  *	@file: file handle to board
487  *
488  *	The temperature device has been closed.
489  */
490 
wdt_temp_release(struct inode * inode,struct file * file)491 static int wdt_temp_release(struct inode *inode, struct file *file)
492 {
493 	return 0;
494 }
495 
496 /**
497  *	wdt_notify_sys:
498  *	@this: our notifier block
499  *	@code: the event being reported
500  *	@unused: unused
501  *
502  *	Our notifier is called on system shutdowns. We want to turn the card
503  *	off at reboot otherwise the machine will reboot again during memory
504  *	test or worse yet during the following fsck. This would suck, in fact
505  *	trust me - if it happens it does suck.
506  */
507 
wdt_notify_sys(struct notifier_block * this,unsigned long code,void * unused)508 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
509 	void *unused)
510 {
511 	if (code == SYS_DOWN || code == SYS_HALT)
512 		wdt_stop();
513 	return NOTIFY_DONE;
514 }
515 
516 /*
517  *	Kernel Interfaces
518  */
519 
520 
521 static const struct file_operations wdt_fops = {
522 	.owner		= THIS_MODULE,
523 	.llseek		= no_llseek,
524 	.write		= wdt_write,
525 	.unlocked_ioctl	= wdt_ioctl,
526 	.compat_ioctl	= compat_ptr_ioctl,
527 	.open		= wdt_open,
528 	.release	= wdt_release,
529 };
530 
531 static struct miscdevice wdt_miscdev = {
532 	.minor	= WATCHDOG_MINOR,
533 	.name	= "watchdog",
534 	.fops	= &wdt_fops,
535 };
536 
537 static const struct file_operations wdt_temp_fops = {
538 	.owner		= THIS_MODULE,
539 	.llseek		= no_llseek,
540 	.read		= wdt_temp_read,
541 	.open		= wdt_temp_open,
542 	.release	= wdt_temp_release,
543 };
544 
545 static struct miscdevice temp_miscdev = {
546 	.minor	= TEMP_MINOR,
547 	.name	= "temperature",
548 	.fops	= &wdt_temp_fops,
549 };
550 
551 /*
552  *	The WDT card needs to learn about soft shutdowns in order to
553  *	turn the timebomb registers off.
554  */
555 
556 static struct notifier_block wdt_notifier = {
557 	.notifier_call = wdt_notify_sys,
558 };
559 
560 /**
561  *	wdt_exit:
562  *
563  *	Unload the watchdog. You cannot do this with any file handles open.
564  *	If your watchdog is set to continue ticking on close and you unload
565  *	it, well it keeps ticking. We won't get the interrupt but the board
566  *	will not touch PC memory so all is fine. You just have to load a new
567  *	module in 60 seconds or reboot.
568  */
569 
wdt_exit(void)570 static void __exit wdt_exit(void)
571 {
572 	misc_deregister(&wdt_miscdev);
573 	if (type == 501)
574 		misc_deregister(&temp_miscdev);
575 	unregister_reboot_notifier(&wdt_notifier);
576 	free_irq(irq, NULL);
577 	release_region(io, 8);
578 }
579 
580 /**
581  *	wdt_init:
582  *
583  *	Set up the WDT watchdog board. All we have to do is grab the
584  *	resources we require and bitch if anyone beat us to them.
585  *	The open() function will actually kick the board off.
586  */
587 
wdt_init(void)588 static int __init wdt_init(void)
589 {
590 	int ret;
591 
592 	if (type != 500 && type != 501) {
593 		pr_err("unknown card type '%d'\n", type);
594 		return -ENODEV;
595 	}
596 
597 	/* Check that the heartbeat value is within it's range;
598 	   if not reset to the default */
599 	if (wdt_set_heartbeat(heartbeat)) {
600 		wdt_set_heartbeat(WD_TIMO);
601 		pr_info("heartbeat value must be 0 < heartbeat < 65536, using %d\n",
602 			WD_TIMO);
603 	}
604 
605 	if (!request_region(io, 8, "wdt501p")) {
606 		pr_err("I/O address 0x%04x already in use\n", io);
607 		ret = -EBUSY;
608 		goto out;
609 	}
610 
611 	ret = request_irq(irq, wdt_interrupt, 0, "wdt501p", NULL);
612 	if (ret) {
613 		pr_err("IRQ %d is not free\n", irq);
614 		goto outreg;
615 	}
616 
617 	ret = register_reboot_notifier(&wdt_notifier);
618 	if (ret) {
619 		pr_err("cannot register reboot notifier (err=%d)\n", ret);
620 		goto outirq;
621 	}
622 
623 	if (type == 501) {
624 		ret = misc_register(&temp_miscdev);
625 		if (ret) {
626 			pr_err("cannot register miscdev on minor=%d (err=%d)\n",
627 			       TEMP_MINOR, ret);
628 			goto outrbt;
629 		}
630 	}
631 
632 	ret = misc_register(&wdt_miscdev);
633 	if (ret) {
634 		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
635 		       WATCHDOG_MINOR, ret);
636 		goto outmisc;
637 	}
638 
639 	pr_info("WDT500/501-P driver 0.10 at 0x%04x (Interrupt %d). heartbeat=%d sec (nowayout=%d)\n",
640 		io, irq, heartbeat, nowayout);
641 	if (type == 501)
642 		pr_info("Fan Tachometer is %s\n",
643 			tachometer ? "Enabled" : "Disabled");
644 	return 0;
645 
646 outmisc:
647 	if (type == 501)
648 		misc_deregister(&temp_miscdev);
649 outrbt:
650 	unregister_reboot_notifier(&wdt_notifier);
651 outirq:
652 	free_irq(irq, NULL);
653 outreg:
654 	release_region(io, 8);
655 out:
656 	return ret;
657 }
658 
659 module_init(wdt_init);
660 module_exit(wdt_exit);
661 
662 MODULE_AUTHOR("Alan Cox");
663 MODULE_DESCRIPTION("Driver for ISA ICS watchdog cards (WDT500/501)");
664 MODULE_LICENSE("GPL");
665