1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *	SMsC 37B787 Watchdog Timer driver for Linux 2.6.x.x
4  *
5  *	Based on acquirewdt.c by Alan Cox <alan@lxorguk.ukuu.org.uk>
6  *	and some other existing drivers
7  *
8  *	The authors do NOT admit liability nor provide warranty for
9  *	any of this software. This material is provided "AS-IS" in
10  *	the hope that it may be useful for others.
11  *
12  *	(C) Copyright 2003-2006  Sven Anders <anders@anduras.de>
13  *
14  *  History:
15  *	2003 - Created version 1.0 for Linux 2.4.x.
16  *	2006 - Ported to Linux 2.6, added nowayout and MAGICCLOSE
17  *	       features. Released version 1.1
18  *
19  *  Theory of operation:
20  *
21  *	A Watchdog Timer (WDT) is a hardware circuit that can
22  *	reset the computer system in case of a software fault.
23  *	You probably knew that already.
24  *
25  *	Usually a userspace daemon will notify the kernel WDT driver
26  *	via the /dev/watchdog special device file that userspace is
27  *	still alive, at regular intervals.  When such a notification
28  *	occurs, the driver will usually tell the hardware watchdog
29  *	that everything is in order, and that the watchdog should wait
30  *	for yet another little while to reset the system.
31  *	If userspace fails (RAM error, kernel bug, whatever), the
32  *	notifications cease to occur, and the hardware watchdog will
33  *	reset the system (causing a reboot) after the timeout occurs.
34  *
35  * Create device with:
36  *  mknod /dev/watchdog c 10 130
37  *
38  * For an example userspace keep-alive daemon, see:
39  *   Documentation/watchdog/wdt.rst
40  */
41 
42 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
43 
44 #include <linux/module.h>
45 #include <linux/moduleparam.h>
46 #include <linux/types.h>
47 #include <linux/miscdevice.h>
48 #include <linux/watchdog.h>
49 #include <linux/delay.h>
50 #include <linux/fs.h>
51 #include <linux/ioport.h>
52 #include <linux/notifier.h>
53 #include <linux/reboot.h>
54 #include <linux/init.h>
55 #include <linux/spinlock.h>
56 #include <linux/io.h>
57 #include <linux/uaccess.h>
58 
59 
60 /* enable support for minutes as units? */
61 /* (does not always work correctly, so disabled by default!) */
62 #define SMSC_SUPPORT_MINUTES
63 #undef SMSC_SUPPORT_MINUTES
64 
65 #define MAX_TIMEOUT     255
66 
67 #define UNIT_SECOND     0
68 #define UNIT_MINUTE     1
69 
70 #define VERSION		"1.1"
71 
72 #define IOPORT		0x3F0
73 #define IOPORT_SIZE     2
74 #define IODEV_NO	8
75 
76 static int unit = UNIT_SECOND;	/* timer's unit */
77 static int timeout = 60;	/* timeout value: default is 60 "units" */
78 static unsigned long timer_enabled;   /* is the timer enabled? */
79 
80 static char expect_close;       /* is the close expected? */
81 
82 static DEFINE_SPINLOCK(io_lock);/* to guard the watchdog from io races */
83 
84 static bool nowayout = WATCHDOG_NOWAYOUT;
85 
86 /* -- Low level function ----------------------------------------*/
87 
88 /* unlock the IO chip */
89 
open_io_config(void)90 static inline void open_io_config(void)
91 {
92 	outb(0x55, IOPORT);
93 	mdelay(1);
94 	outb(0x55, IOPORT);
95 }
96 
97 /* lock the IO chip */
close_io_config(void)98 static inline void close_io_config(void)
99 {
100 	outb(0xAA, IOPORT);
101 }
102 
103 /* select the IO device */
select_io_device(unsigned char devno)104 static inline void select_io_device(unsigned char devno)
105 {
106 	outb(0x07, IOPORT);
107 	outb(devno, IOPORT+1);
108 }
109 
110 /* write to the control register */
write_io_cr(unsigned char reg,unsigned char data)111 static inline void write_io_cr(unsigned char reg, unsigned char data)
112 {
113 	outb(reg, IOPORT);
114 	outb(data, IOPORT+1);
115 }
116 
117 /* read from the control register */
read_io_cr(unsigned char reg)118 static inline char read_io_cr(unsigned char reg)
119 {
120 	outb(reg, IOPORT);
121 	return inb(IOPORT+1);
122 }
123 
124 /* -- Medium level functions ------------------------------------*/
125 
gpio_bit12(unsigned char reg)126 static inline void gpio_bit12(unsigned char reg)
127 {
128 	/* -- General Purpose I/O Bit 1.2 --
129 	 * Bit 0,   In/Out: 0 = Output, 1 = Input
130 	 * Bit 1,   Polarity: 0 = No Invert, 1 = Invert
131 	 * Bit 2,   Group Enable Intr.: 0 = Disable, 1 = Enable
132 	 * Bit 3/4, Function select: 00 = GPI/O, 01 = WDT, 10 = P17,
133 	 *                           11 = Either Edge Triggered Intr. 2
134 	 * Bit 5/6  (Reserved)
135 	 * Bit 7,   Output Type: 0 = Push Pull Bit, 1 = Open Drain
136 	 */
137 	write_io_cr(0xE2, reg);
138 }
139 
gpio_bit13(unsigned char reg)140 static inline void gpio_bit13(unsigned char reg)
141 {
142 	/* -- General Purpose I/O Bit 1.3 --
143 	 * Bit 0,  In/Out: 0 = Output, 1 = Input
144 	 * Bit 1,  Polarity: 0 = No Invert, 1 = Invert
145 	 * Bit 2,  Group Enable Intr.: 0 = Disable, 1 = Enable
146 	 * Bit 3,  Function select: 0 = GPI/O, 1 = LED
147 	 * Bit 4-6 (Reserved)
148 	 * Bit 7,  Output Type: 0 = Push Pull Bit, 1 = Open Drain
149 	 */
150 	write_io_cr(0xE3, reg);
151 }
152 
wdt_timer_units(unsigned char new_units)153 static inline void wdt_timer_units(unsigned char new_units)
154 {
155 	/* -- Watchdog timer units --
156 	 * Bit 0-6 (Reserved)
157 	 * Bit 7,  WDT Time-out Value Units Select
158 	 *         (0 = Minutes, 1 = Seconds)
159 	 */
160 	write_io_cr(0xF1, new_units);
161 }
162 
wdt_timeout_value(unsigned char new_timeout)163 static inline void wdt_timeout_value(unsigned char new_timeout)
164 {
165 	/* -- Watchdog Timer Time-out Value --
166 	 * Bit 0-7 Binary coded units (0=Disabled, 1..255)
167 	 */
168 	write_io_cr(0xF2, new_timeout);
169 }
170 
wdt_timer_conf(unsigned char conf)171 static inline void wdt_timer_conf(unsigned char conf)
172 {
173 	/* -- Watchdog timer configuration --
174 	 * Bit 0   Joystick enable: 0* = No Reset, 1 = Reset WDT upon
175 	 *							Gameport I/O
176 	 * Bit 1   Keyboard enable: 0* = No Reset, 1 = Reset WDT upon KBD Intr.
177 	 * Bit 2   Mouse enable: 0* = No Reset, 1 = Reset WDT upon Mouse Intr
178 	 * Bit 3   Reset the timer
179 	 *         (Wrong in SMsC documentation? Given as: PowerLED Timout
180 	 *							Enabled)
181 	 * Bit 4-7 WDT Interrupt Mapping: (0000* = Disabled,
182 	 *            0001=IRQ1, 0010=(Invalid), 0011=IRQ3 to 1111=IRQ15)
183 	 */
184 	write_io_cr(0xF3, conf);
185 }
186 
wdt_timer_ctrl(unsigned char reg)187 static inline void wdt_timer_ctrl(unsigned char reg)
188 {
189 	/* -- Watchdog timer control --
190 	 * Bit 0   Status Bit: 0 = Timer counting, 1 = Timeout occurred
191 	 * Bit 1   Power LED Toggle: 0 = Disable Toggle, 1 = Toggle at 1 Hz
192 	 * Bit 2   Force Timeout: 1 = Forces WD timeout event (self-cleaning)
193 	 * Bit 3   P20 Force Timeout enabled:
194 	 *          0 = P20 activity does not generate the WD timeout event
195 	 *          1 = P20 Allows rising edge of P20, from the keyboard
196 	 *              controller, to force the WD timeout event.
197 	 * Bit 4   (Reserved)
198 	 * -- Soft power management --
199 	 * Bit 5   Stop Counter: 1 = Stop software power down counter
200 	 *            set via register 0xB8, (self-cleaning)
201 	 *            (Upon read: 0 = Counter running, 1 = Counter stopped)
202 	 * Bit 6   Restart Counter: 1 = Restart software power down counter
203 	 *            set via register 0xB8, (self-cleaning)
204 	 * Bit 7   SPOFF: 1 = Force software power down (self-cleaning)
205 	 */
206 	write_io_cr(0xF4, reg);
207 }
208 
209 /* -- Higher level functions ------------------------------------*/
210 
211 /* initialize watchdog */
212 
wb_smsc_wdt_initialize(void)213 static void wb_smsc_wdt_initialize(void)
214 {
215 	unsigned char old;
216 
217 	spin_lock(&io_lock);
218 	open_io_config();
219 	select_io_device(IODEV_NO);
220 
221 	/* enable the watchdog */
222 	gpio_bit13(0x08);  /* Select pin 80 = LED not GPIO */
223 	gpio_bit12(0x0A);  /* Set pin 79 = WDT not
224 			      GPIO/Output/Polarity=Invert */
225 	/* disable the timeout */
226 	wdt_timeout_value(0);
227 
228 	/* reset control register */
229 	wdt_timer_ctrl(0x00);
230 
231 	/* reset configuration register */
232 	wdt_timer_conf(0x00);
233 
234 	/* read old (timer units) register */
235 	old = read_io_cr(0xF1) & 0x7F;
236 	if (unit == UNIT_SECOND)
237 		old |= 0x80;	/* set to seconds */
238 
239 	/* set the watchdog timer units */
240 	wdt_timer_units(old);
241 
242 	close_io_config();
243 	spin_unlock(&io_lock);
244 }
245 
246 /* shutdown the watchdog */
247 
wb_smsc_wdt_shutdown(void)248 static void wb_smsc_wdt_shutdown(void)
249 {
250 	spin_lock(&io_lock);
251 	open_io_config();
252 	select_io_device(IODEV_NO);
253 
254 	/* disable the watchdog */
255 	gpio_bit13(0x09);
256 	gpio_bit12(0x09);
257 
258 	/* reset watchdog config register */
259 	wdt_timer_conf(0x00);
260 
261 	/* reset watchdog control register */
262 	wdt_timer_ctrl(0x00);
263 
264 	/* disable timeout */
265 	wdt_timeout_value(0x00);
266 
267 	close_io_config();
268 	spin_unlock(&io_lock);
269 }
270 
271 /* set timeout => enable watchdog */
272 
wb_smsc_wdt_set_timeout(unsigned char new_timeout)273 static void wb_smsc_wdt_set_timeout(unsigned char new_timeout)
274 {
275 	spin_lock(&io_lock);
276 	open_io_config();
277 	select_io_device(IODEV_NO);
278 
279 	/* set Power LED to blink, if we enable the timeout */
280 	wdt_timer_ctrl((new_timeout == 0) ? 0x00 : 0x02);
281 
282 	/* set timeout value */
283 	wdt_timeout_value(new_timeout);
284 
285 	close_io_config();
286 	spin_unlock(&io_lock);
287 }
288 
289 /* get timeout */
290 
wb_smsc_wdt_get_timeout(void)291 static unsigned char wb_smsc_wdt_get_timeout(void)
292 {
293 	unsigned char set_timeout;
294 
295 	spin_lock(&io_lock);
296 	open_io_config();
297 	select_io_device(IODEV_NO);
298 	set_timeout = read_io_cr(0xF2);
299 	close_io_config();
300 	spin_unlock(&io_lock);
301 
302 	return set_timeout;
303 }
304 
305 /* disable watchdog */
306 
wb_smsc_wdt_disable(void)307 static void wb_smsc_wdt_disable(void)
308 {
309 	/* set the timeout to 0 to disable the watchdog */
310 	wb_smsc_wdt_set_timeout(0);
311 }
312 
313 /* enable watchdog by setting the current timeout */
314 
wb_smsc_wdt_enable(void)315 static void wb_smsc_wdt_enable(void)
316 {
317 	/* set the current timeout... */
318 	wb_smsc_wdt_set_timeout(timeout);
319 }
320 
321 /* reset the timer */
322 
wb_smsc_wdt_reset_timer(void)323 static void wb_smsc_wdt_reset_timer(void)
324 {
325 	spin_lock(&io_lock);
326 	open_io_config();
327 	select_io_device(IODEV_NO);
328 
329 	/* reset the timer */
330 	wdt_timeout_value(timeout);
331 	wdt_timer_conf(0x08);
332 
333 	close_io_config();
334 	spin_unlock(&io_lock);
335 }
336 
337 /* return, if the watchdog is enabled (timeout is set...) */
338 
wb_smsc_wdt_status(void)339 static int wb_smsc_wdt_status(void)
340 {
341 	return (wb_smsc_wdt_get_timeout() == 0) ? 0 : WDIOF_KEEPALIVEPING;
342 }
343 
344 
345 /* -- File operations -------------------------------------------*/
346 
347 /* open => enable watchdog and set initial timeout */
348 
wb_smsc_wdt_open(struct inode * inode,struct file * file)349 static int wb_smsc_wdt_open(struct inode *inode, struct file *file)
350 {
351 	/* /dev/watchdog can only be opened once */
352 
353 	if (test_and_set_bit(0, &timer_enabled))
354 		return -EBUSY;
355 
356 	if (nowayout)
357 		__module_get(THIS_MODULE);
358 
359 	/* Reload and activate timer */
360 	wb_smsc_wdt_enable();
361 
362 	pr_info("Watchdog enabled. Timeout set to %d %s\n",
363 		timeout, (unit == UNIT_SECOND) ? "second(s)" : "minute(s)");
364 
365 	return stream_open(inode, file);
366 }
367 
368 /* close => shut off the timer */
369 
wb_smsc_wdt_release(struct inode * inode,struct file * file)370 static int wb_smsc_wdt_release(struct inode *inode, struct file *file)
371 {
372 	/* Shut off the timer. */
373 
374 	if (expect_close == 42) {
375 		wb_smsc_wdt_disable();
376 		pr_info("Watchdog disabled, sleeping again...\n");
377 	} else {
378 		pr_crit("Unexpected close, not stopping watchdog!\n");
379 		wb_smsc_wdt_reset_timer();
380 	}
381 
382 	clear_bit(0, &timer_enabled);
383 	expect_close = 0;
384 	return 0;
385 }
386 
387 /* write => update the timer to keep the machine alive */
388 
wb_smsc_wdt_write(struct file * file,const char __user * data,size_t len,loff_t * ppos)389 static ssize_t wb_smsc_wdt_write(struct file *file, const char __user *data,
390 				 size_t len, loff_t *ppos)
391 {
392 	/* See if we got the magic character 'V' and reload the timer */
393 	if (len) {
394 		if (!nowayout) {
395 			size_t i;
396 
397 			/* reset expect flag */
398 			expect_close = 0;
399 
400 			/* scan to see whether or not we got the
401 			   magic character */
402 			for (i = 0; i != len; i++) {
403 				char c;
404 				if (get_user(c, data + i))
405 					return -EFAULT;
406 				if (c == 'V')
407 					expect_close = 42;
408 			}
409 		}
410 
411 		/* someone wrote to us, we should reload the timer */
412 		wb_smsc_wdt_reset_timer();
413 	}
414 	return len;
415 }
416 
417 /* ioctl => control interface */
418 
wb_smsc_wdt_ioctl(struct file * file,unsigned int cmd,unsigned long arg)419 static long wb_smsc_wdt_ioctl(struct file *file,
420 					unsigned int cmd, unsigned long arg)
421 {
422 	int new_timeout;
423 
424 	union {
425 		struct watchdog_info __user *ident;
426 		int __user *i;
427 	} uarg;
428 
429 	static const struct watchdog_info ident = {
430 		.options =		WDIOF_KEEPALIVEPING |
431 					WDIOF_SETTIMEOUT |
432 					WDIOF_MAGICCLOSE,
433 		.firmware_version =	0,
434 		.identity =		"SMsC 37B787 Watchdog",
435 	};
436 
437 	uarg.i = (int __user *)arg;
438 
439 	switch (cmd) {
440 	case WDIOC_GETSUPPORT:
441 		return copy_to_user(uarg.ident, &ident, sizeof(ident))
442 								? -EFAULT : 0;
443 	case WDIOC_GETSTATUS:
444 		return put_user(wb_smsc_wdt_status(), uarg.i);
445 	case WDIOC_GETBOOTSTATUS:
446 		return put_user(0, uarg.i);
447 	case WDIOC_SETOPTIONS:
448 	{
449 		int options, retval = -EINVAL;
450 
451 		if (get_user(options, uarg.i))
452 			return -EFAULT;
453 
454 		if (options & WDIOS_DISABLECARD) {
455 			wb_smsc_wdt_disable();
456 			retval = 0;
457 		}
458 		if (options & WDIOS_ENABLECARD) {
459 			wb_smsc_wdt_enable();
460 			retval = 0;
461 		}
462 		return retval;
463 	}
464 	case WDIOC_KEEPALIVE:
465 		wb_smsc_wdt_reset_timer();
466 		return 0;
467 	case WDIOC_SETTIMEOUT:
468 		if (get_user(new_timeout, uarg.i))
469 			return -EFAULT;
470 		/* the API states this is given in secs */
471 		if (unit == UNIT_MINUTE)
472 			new_timeout /= 60;
473 		if (new_timeout < 0 || new_timeout > MAX_TIMEOUT)
474 			return -EINVAL;
475 		timeout = new_timeout;
476 		wb_smsc_wdt_set_timeout(timeout);
477 		fallthrough;	/* and return the new timeout */
478 	case WDIOC_GETTIMEOUT:
479 		new_timeout = timeout;
480 		if (unit == UNIT_MINUTE)
481 			new_timeout *= 60;
482 		return put_user(new_timeout, uarg.i);
483 	default:
484 		return -ENOTTY;
485 	}
486 }
487 
488 /* -- Notifier funtions -----------------------------------------*/
489 
wb_smsc_wdt_notify_sys(struct notifier_block * this,unsigned long code,void * unused)490 static int wb_smsc_wdt_notify_sys(struct notifier_block *this,
491 					unsigned long code, void *unused)
492 {
493 	if (code == SYS_DOWN || code == SYS_HALT) {
494 		/* set timeout to 0, to avoid possible race-condition */
495 		timeout = 0;
496 		wb_smsc_wdt_disable();
497 	}
498 	return NOTIFY_DONE;
499 }
500 
501 /* -- Module's structures ---------------------------------------*/
502 
503 static const struct file_operations wb_smsc_wdt_fops = {
504 	.owner	  = THIS_MODULE,
505 	.write		= wb_smsc_wdt_write,
506 	.unlocked_ioctl	= wb_smsc_wdt_ioctl,
507 	.compat_ioctl	= compat_ptr_ioctl,
508 	.open		= wb_smsc_wdt_open,
509 	.release	= wb_smsc_wdt_release,
510 };
511 
512 static struct notifier_block wb_smsc_wdt_notifier = {
513 	.notifier_call  = wb_smsc_wdt_notify_sys,
514 };
515 
516 static struct miscdevice wb_smsc_wdt_miscdev = {
517 	.minor		= WATCHDOG_MINOR,
518 	.name		= "watchdog",
519 	.fops		= &wb_smsc_wdt_fops,
520 };
521 
522 /* -- Module init functions -------------------------------------*/
523 
524 /* module's "constructor" */
525 
wb_smsc_wdt_init(void)526 static int __init wb_smsc_wdt_init(void)
527 {
528 	int ret;
529 
530 	pr_info("SMsC 37B787 watchdog component driver "
531 		VERSION " initialising...\n");
532 
533 	if (!request_region(IOPORT, IOPORT_SIZE, "SMsC 37B787 watchdog")) {
534 		pr_err("Unable to register IO port %#x\n", IOPORT);
535 		ret = -EBUSY;
536 		goto out_pnp;
537 	}
538 
539 	/* set new maximum, if it's too big */
540 	if (timeout > MAX_TIMEOUT)
541 		timeout = MAX_TIMEOUT;
542 
543 	/* init the watchdog timer */
544 	wb_smsc_wdt_initialize();
545 
546 	ret = register_reboot_notifier(&wb_smsc_wdt_notifier);
547 	if (ret) {
548 		pr_err("Unable to register reboot notifier err = %d\n", ret);
549 		goto out_io;
550 	}
551 
552 	ret = misc_register(&wb_smsc_wdt_miscdev);
553 	if (ret) {
554 		pr_err("Unable to register miscdev on minor %d\n",
555 		       WATCHDOG_MINOR);
556 		goto out_rbt;
557 	}
558 
559 	/* output info */
560 	pr_info("Timeout set to %d %s\n",
561 		timeout, (unit == UNIT_SECOND) ? "second(s)" : "minute(s)");
562 	pr_info("Watchdog initialized and sleeping (nowayout=%d)...\n",
563 		nowayout);
564 out_clean:
565 	return ret;
566 
567 out_rbt:
568 	unregister_reboot_notifier(&wb_smsc_wdt_notifier);
569 
570 out_io:
571 	release_region(IOPORT, IOPORT_SIZE);
572 
573 out_pnp:
574 	goto out_clean;
575 }
576 
577 /* module's "destructor" */
578 
wb_smsc_wdt_exit(void)579 static void __exit wb_smsc_wdt_exit(void)
580 {
581 	/* Stop the timer before we leave */
582 	if (!nowayout) {
583 		wb_smsc_wdt_shutdown();
584 		pr_info("Watchdog disabled\n");
585 	}
586 
587 	misc_deregister(&wb_smsc_wdt_miscdev);
588 	unregister_reboot_notifier(&wb_smsc_wdt_notifier);
589 	release_region(IOPORT, IOPORT_SIZE);
590 
591 	pr_info("SMsC 37B787 watchdog component driver removed\n");
592 }
593 
594 module_init(wb_smsc_wdt_init);
595 module_exit(wb_smsc_wdt_exit);
596 
597 MODULE_AUTHOR("Sven Anders <anders@anduras.de>");
598 MODULE_DESCRIPTION("Driver for SMsC 37B787 watchdog component (Version "
599 								VERSION ")");
600 MODULE_LICENSE("GPL");
601 
602 #ifdef SMSC_SUPPORT_MINUTES
603 module_param(unit, int, 0);
604 MODULE_PARM_DESC(unit,
605 		"set unit to use, 0=seconds or 1=minutes, default is 0");
606 #endif
607 
608 module_param(timeout, int, 0);
609 MODULE_PARM_DESC(timeout, "range is 1-255 units, default is 60");
610 
611 module_param(nowayout, bool, 0);
612 MODULE_PARM_DESC(nowayout,
613 		"Watchdog cannot be stopped once started (default="
614 				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
615