1 /*
2  *	SMsC 37B787 Watchdog Timer driver for Linux 2.6.x.x
3  *
4  *	Based on acquirewdt.c by Alan Cox <alan@lxorguk.ukuu.org.uk>
5  *	and some other existing drivers
6  *
7  *	This program is free software; you can redistribute it and/or
8  *	modify it under the terms of the GNU General Public License
9  *	as published by the Free Software Foundation; either version
10  *	2 of the License, or (at your option) any later version.
11  *
12  *	The authors do NOT admit liability nor provide warranty for
13  *	any of this software. This material is provided "AS-IS" in
14  *	the hope that it may be useful for others.
15  *
16  *	(C) Copyright 2003-2006  Sven Anders <anders@anduras.de>
17  *
18  *  History:
19  *	2003 - Created version 1.0 for Linux 2.4.x.
20  *	2006 - Ported to Linux 2.6, added nowayout and MAGICCLOSE
21  *	       features. Released version 1.1
22  *
23  *  Theory of operation:
24  *
25  *	A Watchdog Timer (WDT) is a hardware circuit that can
26  *	reset the computer system in case of a software fault.
27  *	You probably knew that already.
28  *
29  *	Usually a userspace daemon will notify the kernel WDT driver
30  *	via the /dev/watchdog special device file that userspace is
31  *	still alive, at regular intervals.  When such a notification
32  *	occurs, the driver will usually tell the hardware watchdog
33  *	that everything is in order, and that the watchdog should wait
34  *	for yet another little while to reset the system.
35  *	If userspace fails (RAM error, kernel bug, whatever), the
36  *	notifications cease to occur, and the hardware watchdog will
37  *	reset the system (causing a reboot) after the timeout occurs.
38  *
39  * Create device with:
40  *  mknod /dev/watchdog c 10 130
41  *
42  * For an example userspace keep-alive daemon, see:
43  *   Documentation/watchdog/wdt.txt
44  */
45 
46 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
47 
48 #include <linux/module.h>
49 #include <linux/moduleparam.h>
50 #include <linux/types.h>
51 #include <linux/miscdevice.h>
52 #include <linux/watchdog.h>
53 #include <linux/delay.h>
54 #include <linux/fs.h>
55 #include <linux/ioport.h>
56 #include <linux/notifier.h>
57 #include <linux/reboot.h>
58 #include <linux/init.h>
59 #include <linux/spinlock.h>
60 #include <linux/io.h>
61 #include <linux/uaccess.h>
62 
63 
64 /* enable support for minutes as units? */
65 /* (does not always work correctly, so disabled by default!) */
66 #define SMSC_SUPPORT_MINUTES
67 #undef SMSC_SUPPORT_MINUTES
68 
69 #define MAX_TIMEOUT     255
70 
71 #define UNIT_SECOND     0
72 #define UNIT_MINUTE     1
73 
74 #define VERSION		"1.1"
75 
76 #define IOPORT		0x3F0
77 #define IOPORT_SIZE     2
78 #define IODEV_NO	8
79 
80 static int unit = UNIT_SECOND;	/* timer's unit */
81 static int timeout = 60;	/* timeout value: default is 60 "units" */
82 static unsigned long timer_enabled;   /* is the timer enabled? */
83 
84 static char expect_close;       /* is the close expected? */
85 
86 static DEFINE_SPINLOCK(io_lock);/* to guard the watchdog from io races */
87 
88 static bool nowayout = WATCHDOG_NOWAYOUT;
89 
90 /* -- Low level function ----------------------------------------*/
91 
92 /* unlock the IO chip */
93 
94 static inline void open_io_config(void)
95 {
96 	outb(0x55, IOPORT);
97 	mdelay(1);
98 	outb(0x55, IOPORT);
99 }
100 
101 /* lock the IO chip */
102 static inline void close_io_config(void)
103 {
104 	outb(0xAA, IOPORT);
105 }
106 
107 /* select the IO device */
108 static inline void select_io_device(unsigned char devno)
109 {
110 	outb(0x07, IOPORT);
111 	outb(devno, IOPORT+1);
112 }
113 
114 /* write to the control register */
115 static inline void write_io_cr(unsigned char reg, unsigned char data)
116 {
117 	outb(reg, IOPORT);
118 	outb(data, IOPORT+1);
119 }
120 
121 /* read from the control register */
122 static inline char read_io_cr(unsigned char reg)
123 {
124 	outb(reg, IOPORT);
125 	return inb(IOPORT+1);
126 }
127 
128 /* -- Medium level functions ------------------------------------*/
129 
130 static inline void gpio_bit12(unsigned char reg)
131 {
132 	/* -- General Purpose I/O Bit 1.2 --
133 	 * Bit 0,   In/Out: 0 = Output, 1 = Input
134 	 * Bit 1,   Polarity: 0 = No Invert, 1 = Invert
135 	 * Bit 2,   Group Enable Intr.: 0 = Disable, 1 = Enable
136 	 * Bit 3/4, Function select: 00 = GPI/O, 01 = WDT, 10 = P17,
137 	 *                           11 = Either Edge Triggered Intr. 2
138 	 * Bit 5/6  (Reserved)
139 	 * Bit 7,   Output Type: 0 = Push Pull Bit, 1 = Open Drain
140 	 */
141 	write_io_cr(0xE2, reg);
142 }
143 
144 static inline void gpio_bit13(unsigned char reg)
145 {
146 	/* -- General Purpose I/O Bit 1.3 --
147 	 * Bit 0,  In/Out: 0 = Output, 1 = Input
148 	 * Bit 1,  Polarity: 0 = No Invert, 1 = Invert
149 	 * Bit 2,  Group Enable Intr.: 0 = Disable, 1 = Enable
150 	 * Bit 3,  Function select: 0 = GPI/O, 1 = LED
151 	 * Bit 4-6 (Reserved)
152 	 * Bit 7,  Output Type: 0 = Push Pull Bit, 1 = Open Drain
153 	 */
154 	write_io_cr(0xE3, reg);
155 }
156 
157 static inline void wdt_timer_units(unsigned char new_units)
158 {
159 	/* -- Watchdog timer units --
160 	 * Bit 0-6 (Reserved)
161 	 * Bit 7,  WDT Time-out Value Units Select
162 	 *         (0 = Minutes, 1 = Seconds)
163 	 */
164 	write_io_cr(0xF1, new_units);
165 }
166 
167 static inline void wdt_timeout_value(unsigned char new_timeout)
168 {
169 	/* -- Watchdog Timer Time-out Value --
170 	 * Bit 0-7 Binary coded units (0=Disabled, 1..255)
171 	 */
172 	write_io_cr(0xF2, new_timeout);
173 }
174 
175 static inline void wdt_timer_conf(unsigned char conf)
176 {
177 	/* -- Watchdog timer configuration --
178 	 * Bit 0   Joystick enable: 0* = No Reset, 1 = Reset WDT upon
179 	 *							Gameport I/O
180 	 * Bit 1   Keyboard enable: 0* = No Reset, 1 = Reset WDT upon KBD Intr.
181 	 * Bit 2   Mouse enable: 0* = No Reset, 1 = Reset WDT upon Mouse Intr
182 	 * Bit 3   Reset the timer
183 	 *         (Wrong in SMsC documentation? Given as: PowerLED Timout
184 	 *							Enabled)
185 	 * Bit 4-7 WDT Interrupt Mapping: (0000* = Disabled,
186 	 *            0001=IRQ1, 0010=(Invalid), 0011=IRQ3 to 1111=IRQ15)
187 	 */
188 	write_io_cr(0xF3, conf);
189 }
190 
191 static inline void wdt_timer_ctrl(unsigned char reg)
192 {
193 	/* -- Watchdog timer control --
194 	 * Bit 0   Status Bit: 0 = Timer counting, 1 = Timeout occurred
195 	 * Bit 1   Power LED Toggle: 0 = Disable Toggle, 1 = Toggle at 1 Hz
196 	 * Bit 2   Force Timeout: 1 = Forces WD timeout event (self-cleaning)
197 	 * Bit 3   P20 Force Timeout enabled:
198 	 *          0 = P20 activity does not generate the WD timeout event
199 	 *          1 = P20 Allows rising edge of P20, from the keyboard
200 	 *              controller, to force the WD timeout event.
201 	 * Bit 4   (Reserved)
202 	 * -- Soft power management --
203 	 * Bit 5   Stop Counter: 1 = Stop software power down counter
204 	 *            set via register 0xB8, (self-cleaning)
205 	 *            (Upon read: 0 = Counter running, 1 = Counter stopped)
206 	 * Bit 6   Restart Counter: 1 = Restart software power down counter
207 	 *            set via register 0xB8, (self-cleaning)
208 	 * Bit 7   SPOFF: 1 = Force software power down (self-cleaning)
209 	 */
210 	write_io_cr(0xF4, reg);
211 }
212 
213 /* -- Higher level functions ------------------------------------*/
214 
215 /* initialize watchdog */
216 
217 static void wb_smsc_wdt_initialize(void)
218 {
219 	unsigned char old;
220 
221 	spin_lock(&io_lock);
222 	open_io_config();
223 	select_io_device(IODEV_NO);
224 
225 	/* enable the watchdog */
226 	gpio_bit13(0x08);  /* Select pin 80 = LED not GPIO */
227 	gpio_bit12(0x0A);  /* Set pin 79 = WDT not
228 			      GPIO/Output/Polarity=Invert */
229 	/* disable the timeout */
230 	wdt_timeout_value(0);
231 
232 	/* reset control register */
233 	wdt_timer_ctrl(0x00);
234 
235 	/* reset configuration register */
236 	wdt_timer_conf(0x00);
237 
238 	/* read old (timer units) register */
239 	old = read_io_cr(0xF1) & 0x7F;
240 	if (unit == UNIT_SECOND)
241 		old |= 0x80;	/* set to seconds */
242 
243 	/* set the watchdog timer units */
244 	wdt_timer_units(old);
245 
246 	close_io_config();
247 	spin_unlock(&io_lock);
248 }
249 
250 /* shutdown the watchdog */
251 
252 static void wb_smsc_wdt_shutdown(void)
253 {
254 	spin_lock(&io_lock);
255 	open_io_config();
256 	select_io_device(IODEV_NO);
257 
258 	/* disable the watchdog */
259 	gpio_bit13(0x09);
260 	gpio_bit12(0x09);
261 
262 	/* reset watchdog config register */
263 	wdt_timer_conf(0x00);
264 
265 	/* reset watchdog control register */
266 	wdt_timer_ctrl(0x00);
267 
268 	/* disable timeout */
269 	wdt_timeout_value(0x00);
270 
271 	close_io_config();
272 	spin_unlock(&io_lock);
273 }
274 
275 /* set timeout => enable watchdog */
276 
277 static void wb_smsc_wdt_set_timeout(unsigned char new_timeout)
278 {
279 	spin_lock(&io_lock);
280 	open_io_config();
281 	select_io_device(IODEV_NO);
282 
283 	/* set Power LED to blink, if we enable the timeout */
284 	wdt_timer_ctrl((new_timeout == 0) ? 0x00 : 0x02);
285 
286 	/* set timeout value */
287 	wdt_timeout_value(new_timeout);
288 
289 	close_io_config();
290 	spin_unlock(&io_lock);
291 }
292 
293 /* get timeout */
294 
295 static unsigned char wb_smsc_wdt_get_timeout(void)
296 {
297 	unsigned char set_timeout;
298 
299 	spin_lock(&io_lock);
300 	open_io_config();
301 	select_io_device(IODEV_NO);
302 	set_timeout = read_io_cr(0xF2);
303 	close_io_config();
304 	spin_unlock(&io_lock);
305 
306 	return set_timeout;
307 }
308 
309 /* disable watchdog */
310 
311 static void wb_smsc_wdt_disable(void)
312 {
313 	/* set the timeout to 0 to disable the watchdog */
314 	wb_smsc_wdt_set_timeout(0);
315 }
316 
317 /* enable watchdog by setting the current timeout */
318 
319 static void wb_smsc_wdt_enable(void)
320 {
321 	/* set the current timeout... */
322 	wb_smsc_wdt_set_timeout(timeout);
323 }
324 
325 /* reset the timer */
326 
327 static void wb_smsc_wdt_reset_timer(void)
328 {
329 	spin_lock(&io_lock);
330 	open_io_config();
331 	select_io_device(IODEV_NO);
332 
333 	/* reset the timer */
334 	wdt_timeout_value(timeout);
335 	wdt_timer_conf(0x08);
336 
337 	close_io_config();
338 	spin_unlock(&io_lock);
339 }
340 
341 /* return, if the watchdog is enabled (timeout is set...) */
342 
343 static int wb_smsc_wdt_status(void)
344 {
345 	return (wb_smsc_wdt_get_timeout() == 0) ? 0 : WDIOF_KEEPALIVEPING;
346 }
347 
348 
349 /* -- File operations -------------------------------------------*/
350 
351 /* open => enable watchdog and set initial timeout */
352 
353 static int wb_smsc_wdt_open(struct inode *inode, struct file *file)
354 {
355 	/* /dev/watchdog can only be opened once */
356 
357 	if (test_and_set_bit(0, &timer_enabled))
358 		return -EBUSY;
359 
360 	if (nowayout)
361 		__module_get(THIS_MODULE);
362 
363 	/* Reload and activate timer */
364 	wb_smsc_wdt_enable();
365 
366 	pr_info("Watchdog enabled. Timeout set to %d %s\n",
367 		timeout, (unit == UNIT_SECOND) ? "second(s)" : "minute(s)");
368 
369 	return nonseekable_open(inode, file);
370 }
371 
372 /* close => shut off the timer */
373 
374 static int wb_smsc_wdt_release(struct inode *inode, struct file *file)
375 {
376 	/* Shut off the timer. */
377 
378 	if (expect_close == 42) {
379 		wb_smsc_wdt_disable();
380 		pr_info("Watchdog disabled, sleeping again...\n");
381 	} else {
382 		pr_crit("Unexpected close, not stopping watchdog!\n");
383 		wb_smsc_wdt_reset_timer();
384 	}
385 
386 	clear_bit(0, &timer_enabled);
387 	expect_close = 0;
388 	return 0;
389 }
390 
391 /* write => update the timer to keep the machine alive */
392 
393 static ssize_t wb_smsc_wdt_write(struct file *file, const char __user *data,
394 				 size_t len, loff_t *ppos)
395 {
396 	/* See if we got the magic character 'V' and reload the timer */
397 	if (len) {
398 		if (!nowayout) {
399 			size_t i;
400 
401 			/* reset expect flag */
402 			expect_close = 0;
403 
404 			/* scan to see whether or not we got the
405 			   magic character */
406 			for (i = 0; i != len; i++) {
407 				char c;
408 				if (get_user(c, data + i))
409 					return -EFAULT;
410 				if (c == 'V')
411 					expect_close = 42;
412 			}
413 		}
414 
415 		/* someone wrote to us, we should reload the timer */
416 		wb_smsc_wdt_reset_timer();
417 	}
418 	return len;
419 }
420 
421 /* ioctl => control interface */
422 
423 static long wb_smsc_wdt_ioctl(struct file *file,
424 					unsigned int cmd, unsigned long arg)
425 {
426 	int new_timeout;
427 
428 	union {
429 		struct watchdog_info __user *ident;
430 		int __user *i;
431 	} uarg;
432 
433 	static const struct watchdog_info ident = {
434 		.options =		WDIOF_KEEPALIVEPING |
435 					WDIOF_SETTIMEOUT |
436 					WDIOF_MAGICCLOSE,
437 		.firmware_version =	0,
438 		.identity =		"SMsC 37B787 Watchdog",
439 	};
440 
441 	uarg.i = (int __user *)arg;
442 
443 	switch (cmd) {
444 	case WDIOC_GETSUPPORT:
445 		return copy_to_user(uarg.ident, &ident, sizeof(ident))
446 								? -EFAULT : 0;
447 	case WDIOC_GETSTATUS:
448 		return put_user(wb_smsc_wdt_status(), uarg.i);
449 	case WDIOC_GETBOOTSTATUS:
450 		return put_user(0, uarg.i);
451 	case WDIOC_SETOPTIONS:
452 	{
453 		int options, retval = -EINVAL;
454 
455 		if (get_user(options, uarg.i))
456 			return -EFAULT;
457 
458 		if (options & WDIOS_DISABLECARD) {
459 			wb_smsc_wdt_disable();
460 			retval = 0;
461 		}
462 		if (options & WDIOS_ENABLECARD) {
463 			wb_smsc_wdt_enable();
464 			retval = 0;
465 		}
466 		return retval;
467 	}
468 	case WDIOC_KEEPALIVE:
469 		wb_smsc_wdt_reset_timer();
470 		return 0;
471 	case WDIOC_SETTIMEOUT:
472 		if (get_user(new_timeout, uarg.i))
473 			return -EFAULT;
474 		/* the API states this is given in secs */
475 		if (unit == UNIT_MINUTE)
476 			new_timeout /= 60;
477 		if (new_timeout < 0 || new_timeout > MAX_TIMEOUT)
478 			return -EINVAL;
479 		timeout = new_timeout;
480 		wb_smsc_wdt_set_timeout(timeout);
481 		/* fall through - and return the new timeout... */
482 	case WDIOC_GETTIMEOUT:
483 		new_timeout = timeout;
484 		if (unit == UNIT_MINUTE)
485 			new_timeout *= 60;
486 		return put_user(new_timeout, uarg.i);
487 	default:
488 		return -ENOTTY;
489 	}
490 }
491 
492 /* -- Notifier funtions -----------------------------------------*/
493 
494 static int wb_smsc_wdt_notify_sys(struct notifier_block *this,
495 					unsigned long code, void *unused)
496 {
497 	if (code == SYS_DOWN || code == SYS_HALT) {
498 		/* set timeout to 0, to avoid possible race-condition */
499 		timeout = 0;
500 		wb_smsc_wdt_disable();
501 	}
502 	return NOTIFY_DONE;
503 }
504 
505 /* -- Module's structures ---------------------------------------*/
506 
507 static const struct file_operations wb_smsc_wdt_fops = {
508 	.owner	  = THIS_MODULE,
509 	.llseek		= no_llseek,
510 	.write		= wb_smsc_wdt_write,
511 	.unlocked_ioctl	= wb_smsc_wdt_ioctl,
512 	.open		= wb_smsc_wdt_open,
513 	.release	= wb_smsc_wdt_release,
514 };
515 
516 static struct notifier_block wb_smsc_wdt_notifier = {
517 	.notifier_call  = wb_smsc_wdt_notify_sys,
518 };
519 
520 static struct miscdevice wb_smsc_wdt_miscdev = {
521 	.minor		= WATCHDOG_MINOR,
522 	.name		= "watchdog",
523 	.fops		= &wb_smsc_wdt_fops,
524 };
525 
526 /* -- Module init functions -------------------------------------*/
527 
528 /* module's "constructor" */
529 
530 static int __init wb_smsc_wdt_init(void)
531 {
532 	int ret;
533 
534 	pr_info("SMsC 37B787 watchdog component driver "
535 		VERSION " initialising...\n");
536 
537 	if (!request_region(IOPORT, IOPORT_SIZE, "SMsC 37B787 watchdog")) {
538 		pr_err("Unable to register IO port %#x\n", IOPORT);
539 		ret = -EBUSY;
540 		goto out_pnp;
541 	}
542 
543 	/* set new maximum, if it's too big */
544 	if (timeout > MAX_TIMEOUT)
545 		timeout = MAX_TIMEOUT;
546 
547 	/* init the watchdog timer */
548 	wb_smsc_wdt_initialize();
549 
550 	ret = register_reboot_notifier(&wb_smsc_wdt_notifier);
551 	if (ret) {
552 		pr_err("Unable to register reboot notifier err = %d\n", ret);
553 		goto out_io;
554 	}
555 
556 	ret = misc_register(&wb_smsc_wdt_miscdev);
557 	if (ret) {
558 		pr_err("Unable to register miscdev on minor %d\n",
559 		       WATCHDOG_MINOR);
560 		goto out_rbt;
561 	}
562 
563 	/* output info */
564 	pr_info("Timeout set to %d %s\n",
565 		timeout, (unit == UNIT_SECOND) ? "second(s)" : "minute(s)");
566 	pr_info("Watchdog initialized and sleeping (nowayout=%d)...\n",
567 		nowayout);
568 out_clean:
569 	return ret;
570 
571 out_rbt:
572 	unregister_reboot_notifier(&wb_smsc_wdt_notifier);
573 
574 out_io:
575 	release_region(IOPORT, IOPORT_SIZE);
576 
577 out_pnp:
578 	goto out_clean;
579 }
580 
581 /* module's "destructor" */
582 
583 static void __exit wb_smsc_wdt_exit(void)
584 {
585 	/* Stop the timer before we leave */
586 	if (!nowayout) {
587 		wb_smsc_wdt_shutdown();
588 		pr_info("Watchdog disabled\n");
589 	}
590 
591 	misc_deregister(&wb_smsc_wdt_miscdev);
592 	unregister_reboot_notifier(&wb_smsc_wdt_notifier);
593 	release_region(IOPORT, IOPORT_SIZE);
594 
595 	pr_info("SMsC 37B787 watchdog component driver removed\n");
596 }
597 
598 module_init(wb_smsc_wdt_init);
599 module_exit(wb_smsc_wdt_exit);
600 
601 MODULE_AUTHOR("Sven Anders <anders@anduras.de>");
602 MODULE_DESCRIPTION("Driver for SMsC 37B787 watchdog component (Version "
603 								VERSION ")");
604 MODULE_LICENSE("GPL");
605 
606 #ifdef SMSC_SUPPORT_MINUTES
607 module_param(unit, int, 0);
608 MODULE_PARM_DESC(unit,
609 		"set unit to use, 0=seconds or 1=minutes, default is 0");
610 #endif
611 
612 module_param(timeout, int, 0);
613 MODULE_PARM_DESC(timeout, "range is 1-255 units, default is 60");
614 
615 module_param(nowayout, bool, 0);
616 MODULE_PARM_DESC(nowayout,
617 		"Watchdog cannot be stopped once started (default="
618 				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
619