1/*
2 *	W83877F Computer Watchdog Timer driver
3 *
4 *      Based on acquirewdt.c by Alan Cox,
5 *           and sbc60xxwdt.c by Jakob Oestergaard <jakob@unthought.net>
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 2001    Scott Jennings <linuxdrivers@oro.net>
17 *
18 *           4/19 - 2001      [Initial revision]
19 *           9/27 - 2001      Added spinlocking
20 *           4/12 - 2002      [rob@osinvestor.com] Eliminate extra comments
21 *                            Eliminate fop_read
22 *                            Eliminate extra spin_unlock
23 *                            Added KERN_* tags to printks
24 *                            add CONFIG_WATCHDOG_NOWAYOUT support
25 *                            fix possible wdt_is_open race
26 *                            changed watchdog_info to correctly reflect what the driver offers
27 *                            added WDIOC_GETSTATUS, WDIOC_GETBOOTSTATUS, WDIOC_SETTIMEOUT,
28 *                            WDIOC_GETTIMEOUT, and WDIOC_SETOPTIONS ioctls
29 *           09/8 - 2003      [wim@iguana.be] cleanup of trailing spaces
30 *                            added extra printk's for startup problems
31 *                            use module_param
32 *                            made timeout (the emulated heartbeat) a module_param
33 *                            made the keepalive ping an internal subroutine
34 *
35 *  This WDT driver is different from most other Linux WDT
36 *  drivers in that the driver will ping the watchdog by itself,
37 *  because this particular WDT has a very short timeout (1.6
38 *  seconds) and it would be insane to count on any userspace
39 *  daemon always getting scheduled within that time frame.
40 */
41
42#include <linux/module.h>
43#include <linux/moduleparam.h>
44#include <linux/types.h>
45#include <linux/timer.h>
46#include <linux/jiffies.h>
47#include <linux/miscdevice.h>
48#include <linux/watchdog.h>
49#include <linux/fs.h>
50#include <linux/ioport.h>
51#include <linux/notifier.h>
52#include <linux/reboot.h>
53#include <linux/init.h>
54#include <asm/io.h>
55#include <asm/uaccess.h>
56#include <asm/system.h>
57
58#define OUR_NAME "w83877f_wdt"
59#define PFX OUR_NAME ": "
60
61#define ENABLE_W83877F_PORT 0x3F0
62#define ENABLE_W83877F 0x87
63#define DISABLE_W83877F 0xAA
64#define WDT_PING 0x443
65#define WDT_REGISTER 0x14
66#define WDT_ENABLE 0x9C
67#define WDT_DISABLE 0x8C
68
69/*
70 * The W83877F seems to be fixed at 1.6s timeout (at least on the
71 * EMACS PC-104 board I'm using). If we reset the watchdog every
72 * ~250ms we should be safe.  */
73
74#define WDT_INTERVAL (HZ/4+1)
75
76/*
77 * We must not require too good response from the userspace daemon.
78 * Here we require the userspace daemon to send us a heartbeat
79 * char to /dev/watchdog every 30 seconds.
80 */
81
82#define WATCHDOG_TIMEOUT 30            /* 30 sec default timeout */
83static int timeout = WATCHDOG_TIMEOUT; /* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
84module_param(timeout, int, 0);
85MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (1<=timeout<=3600, default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
86
87
88static int nowayout = WATCHDOG_NOWAYOUT;
89module_param(nowayout, int, 0);
90MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
91
92static void wdt_timer_ping(unsigned long);
93static DEFINE_TIMER(timer, wdt_timer_ping, 0, 0);
94static unsigned long next_heartbeat;
95static unsigned long wdt_is_open;
96static char wdt_expect_close;
97static spinlock_t wdt_spinlock;
98
99/*
100 *	Whack the dog
101 */
102
103static void wdt_timer_ping(unsigned long data)
104{
105	/* If we got a heartbeat pulse within the WDT_US_INTERVAL
106	 * we agree to ping the WDT
107	 */
108	if(time_before(jiffies, next_heartbeat))
109	{
110		/* Ping the WDT */
111		spin_lock(&wdt_spinlock);
112
113		/* Ping the WDT by reading from WDT_PING */
114		inb_p(WDT_PING);
115
116		/* Re-set the timer interval */
117		mod_timer(&timer, jiffies + WDT_INTERVAL);
118
119		spin_unlock(&wdt_spinlock);
120
121	} else {
122		printk(KERN_WARNING PFX "Heartbeat lost! Will not ping the watchdog\n");
123	}
124}
125
126/*
127 * Utility routines
128 */
129
130static void wdt_change(int writeval)
131{
132	unsigned long flags;
133	spin_lock_irqsave(&wdt_spinlock, flags);
134
135	/* buy some time */
136	inb_p(WDT_PING);
137
138	/* make W83877F available */
139	outb_p(ENABLE_W83877F,  ENABLE_W83877F_PORT);
140	outb_p(ENABLE_W83877F,  ENABLE_W83877F_PORT);
141
142	/* enable watchdog */
143	outb_p(WDT_REGISTER,    ENABLE_W83877F_PORT);
144	outb_p(writeval,        ENABLE_W83877F_PORT+1);
145
146	/* lock the W8387FF away */
147	outb_p(DISABLE_W83877F, ENABLE_W83877F_PORT);
148
149	spin_unlock_irqrestore(&wdt_spinlock, flags);
150}
151
152static void wdt_startup(void)
153{
154	next_heartbeat = jiffies + (timeout * HZ);
155
156	/* Start the timer */
157	mod_timer(&timer, jiffies + WDT_INTERVAL);
158
159	wdt_change(WDT_ENABLE);
160
161	printk(KERN_INFO PFX "Watchdog timer is now enabled.\n");
162}
163
164static void wdt_turnoff(void)
165{
166	/* Stop the timer */
167	del_timer(&timer);
168
169	wdt_change(WDT_DISABLE);
170
171	printk(KERN_INFO PFX "Watchdog timer is now disabled...\n");
172}
173
174static void wdt_keepalive(void)
175{
176	/* user land ping */
177	next_heartbeat = jiffies + (timeout * HZ);
178}
179
180/*
181 * /dev/watchdog handling
182 */
183
184static ssize_t fop_write(struct file * file, const char __user * buf, size_t count, loff_t * ppos)
185{
186	/* See if we got the magic character 'V' and reload the timer */
187	if(count)
188	{
189		if (!nowayout)
190		{
191			size_t ofs;
192
193			/* note: just in case someone wrote the magic character
194			 * five months ago... */
195			wdt_expect_close = 0;
196
197			/* scan to see whether or not we got the magic character */
198			for(ofs = 0; ofs != count; ofs++)
199			{
200				char c;
201				if (get_user(c, buf + ofs))
202					return -EFAULT;
203				if (c == 'V')
204					wdt_expect_close = 42;
205			}
206		}
207
208		/* someone wrote to us, we should restart timer */
209		wdt_keepalive();
210	}
211	return count;
212}
213
214static int fop_open(struct inode * inode, struct file * file)
215{
216	/* Just in case we're already talking to someone... */
217	if(test_and_set_bit(0, &wdt_is_open))
218		return -EBUSY;
219
220	/* Good, fire up the show */
221	wdt_startup();
222	return nonseekable_open(inode, file);
223}
224
225static int fop_close(struct inode * inode, struct file * file)
226{
227	if(wdt_expect_close == 42)
228		wdt_turnoff();
229	else {
230		del_timer(&timer);
231		printk(KERN_CRIT PFX "device file closed unexpectedly. Will not stop the WDT!\n");
232	}
233	clear_bit(0, &wdt_is_open);
234	wdt_expect_close = 0;
235	return 0;
236}
237
238static int fop_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
239	unsigned long arg)
240{
241	void __user *argp = (void __user *)arg;
242	int __user *p = argp;
243	static struct watchdog_info ident=
244	{
245		.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
246		.firmware_version = 1,
247		.identity = "W83877F",
248	};
249
250	switch(cmd)
251	{
252		default:
253			return -ENOTTY;
254		case WDIOC_GETSUPPORT:
255			return copy_to_user(argp, &ident, sizeof(ident))?-EFAULT:0;
256		case WDIOC_GETSTATUS:
257		case WDIOC_GETBOOTSTATUS:
258			return put_user(0, p);
259		case WDIOC_KEEPALIVE:
260			wdt_keepalive();
261			return 0;
262		case WDIOC_SETOPTIONS:
263		{
264			int new_options, retval = -EINVAL;
265
266			if(get_user(new_options, p))
267				return -EFAULT;
268
269			if(new_options & WDIOS_DISABLECARD) {
270				wdt_turnoff();
271				retval = 0;
272			}
273
274			if(new_options & WDIOS_ENABLECARD) {
275				wdt_startup();
276				retval = 0;
277			}
278
279			return retval;
280		}
281		case WDIOC_SETTIMEOUT:
282		{
283			int new_timeout;
284
285			if(get_user(new_timeout, p))
286				return -EFAULT;
287
288			if(new_timeout < 1 || new_timeout > 3600) /* arbitrary upper limit */
289				return -EINVAL;
290
291			timeout = new_timeout;
292			wdt_keepalive();
293			/* Fall through */
294		}
295		case WDIOC_GETTIMEOUT:
296			return put_user(timeout, p);
297	}
298}
299
300static const struct file_operations wdt_fops = {
301	.owner		= THIS_MODULE,
302	.llseek		= no_llseek,
303	.write		= fop_write,
304	.open		= fop_open,
305	.release	= fop_close,
306	.ioctl		= fop_ioctl,
307};
308
309static struct miscdevice wdt_miscdev = {
310	.minor	= WATCHDOG_MINOR,
311	.name	= "watchdog",
312	.fops	= &wdt_fops,
313};
314
315/*
316 *	Notifier for system down
317 */
318
319static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
320	void *unused)
321{
322	if(code==SYS_DOWN || code==SYS_HALT)
323		wdt_turnoff();
324	return NOTIFY_DONE;
325}
326
327/*
328 *	The WDT needs to learn about soft shutdowns in order to
329 *	turn the timebomb registers off.
330 */
331
332static struct notifier_block wdt_notifier=
333{
334	.notifier_call = wdt_notify_sys,
335};
336
337static void __exit w83877f_wdt_unload(void)
338{
339	wdt_turnoff();
340
341	/* Deregister */
342	misc_deregister(&wdt_miscdev);
343
344	unregister_reboot_notifier(&wdt_notifier);
345	release_region(WDT_PING,1);
346	release_region(ENABLE_W83877F_PORT,2);
347}
348
349static int __init w83877f_wdt_init(void)
350{
351	int rc = -EBUSY;
352
353	spin_lock_init(&wdt_spinlock);
354
355	if(timeout < 1 || timeout > 3600) /* arbitrary upper limit */
356	{
357		timeout = WATCHDOG_TIMEOUT;
358		printk(KERN_INFO PFX "timeout value must be 1<=x<=3600, using %d\n",
359			timeout);
360	}
361
362	if (!request_region(ENABLE_W83877F_PORT, 2, "W83877F WDT"))
363	{
364		printk(KERN_ERR PFX "I/O address 0x%04x already in use\n",
365			ENABLE_W83877F_PORT);
366		rc = -EIO;
367		goto err_out;
368	}
369
370	if (!request_region(WDT_PING, 1, "W8387FF WDT"))
371	{
372		printk(KERN_ERR PFX "I/O address 0x%04x already in use\n",
373			WDT_PING);
374		rc = -EIO;
375		goto err_out_region1;
376	}
377
378	rc = misc_register(&wdt_miscdev);
379	if (rc)
380	{
381		printk(KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n",
382			wdt_miscdev.minor, rc);
383		goto err_out_region2;
384	}
385
386	rc = register_reboot_notifier(&wdt_notifier);
387	if (rc)
388	{
389		printk(KERN_ERR PFX "cannot register reboot notifier (err=%d)\n",
390			rc);
391		goto err_out_miscdev;
392	}
393
394	printk(KERN_INFO PFX "WDT driver for W83877F initialised. timeout=%d sec (nowayout=%d)\n",
395		timeout, nowayout);
396
397	return 0;
398
399err_out_miscdev:
400	misc_deregister(&wdt_miscdev);
401err_out_region2:
402	release_region(WDT_PING,1);
403err_out_region1:
404	release_region(ENABLE_W83877F_PORT,2);
405err_out:
406	return rc;
407}
408
409module_init(w83877f_wdt_init);
410module_exit(w83877f_wdt_unload);
411
412MODULE_AUTHOR("Scott and Bill Jennings");
413MODULE_DESCRIPTION("Driver for watchdog timer in w83877f chip");
414MODULE_LICENSE("GPL");
415MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
416