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
80static int unit = UNIT_SECOND;	/* timer's unit */
81static int timeout = 60;	/* timeout value: default is 60 "units" */
82static unsigned long timer_enabled;   /* is the timer enabled? */
83
84static char expect_close;       /* is the close expected? */
85
86static DEFINE_SPINLOCK(io_lock);/* to guard the watchdog from io races */
87
88static bool nowayout = WATCHDOG_NOWAYOUT;
89
90/* -- Low level function ----------------------------------------*/
91
92/* unlock the IO chip */
93
94static 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 */
102static inline void close_io_config(void)
103{
104	outb(0xAA, IOPORT);
105}
106
107/* select the IO device */
108static 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 */
115static 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 */
122static 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
130static 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
144static 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
157static 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
167static 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
175static 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
191static 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
217static 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
252static 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
277static 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
295static 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
311static 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
319static 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
327static 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
343static 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
353static 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
374static 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
393static 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
423static 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
494static 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
507static 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
516static struct notifier_block wb_smsc_wdt_notifier = {
517	.notifier_call  = wb_smsc_wdt_notify_sys,
518};
519
520static 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
530static 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);
568out_clean:
569	return ret;
570
571out_rbt:
572	unregister_reboot_notifier(&wb_smsc_wdt_notifier);
573
574out_io:
575	release_region(IOPORT, IOPORT_SIZE);
576
577out_pnp:
578	goto out_clean;
579}
580
581/* module's "destructor" */
582
583static 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
598module_init(wb_smsc_wdt_init);
599module_exit(wb_smsc_wdt_exit);
600
601MODULE_AUTHOR("Sven Anders <anders@anduras.de>");
602MODULE_DESCRIPTION("Driver for SMsC 37B787 watchdog component (Version "
603								VERSION ")");
604MODULE_LICENSE("GPL");
605
606#ifdef SMSC_SUPPORT_MINUTES
607module_param(unit, int, 0);
608MODULE_PARM_DESC(unit,
609		"set unit to use, 0=seconds or 1=minutes, default is 0");
610#endif
611
612module_param(timeout, int, 0);
613MODULE_PARM_DESC(timeout, "range is 1-255 units, default is 60");
614
615module_param(nowayout, bool, 0);
616MODULE_PARM_DESC(nowayout,
617		"Watchdog cannot be stopped once started (default="
618				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
619