1/*
2 *	60xx Single Board Computer Watchdog Timer driver for Linux 2.2.x
3 *
4 *      Based on acquirewdt.c by Alan Cox.
5 *
6 *	This program is free software; you can redistribute it and/or
7 *	modify it under the terms of the GNU General Public License
8 *	as published by the Free Software Foundation; either version
9 *	2 of the License, or (at your option) any later version.
10 *
11 *	The author does NOT admit liability nor provide warranty for
12 *	any of this software. This material is provided "AS-IS" in
13 *	the hope that it may be useful for others.
14 *
15 *	(c) Copyright 2000    Jakob Oestergaard <jakob@unthought.net>
16 *
17 *           12/4 - 2000      [Initial revision]
18 *           25/4 - 2000      Added /dev/watchdog support
19 *           09/5 - 2001      [smj@oro.net] fixed fop_write to "return 1" on success
20 *           12/4 - 2002      [rob@osinvestor.com] eliminate fop_read
21 *                            fix possible wdt_is_open race
22 *                            add CONFIG_WATCHDOG_NOWAYOUT support
23 *                            remove lock_kernel/unlock_kernel pairs
24 *                            added KERN_* to printk's
25 *                            got rid of extraneous comments
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 *                            use module_param
31 *                            made timeout (the emulated heartbeat) a module_param
32 *                            made the keepalive ping an internal subroutine
33 *                            made wdt_stop and wdt_start module params
34 *                            added extra printk's for startup problems
35 *                            added MODULE_AUTHOR and MODULE_DESCRIPTION info
36 *
37 *
38 *  This WDT driver is different from the other Linux WDT
39 *  drivers in the following ways:
40 *  *)  The driver will ping the watchdog by itself, because this
41 *      particular WDT has a very short timeout (one second) and it
42 *      would be insane to count on any userspace daemon always
43 *      getting scheduled within that time frame.
44 *
45 */
46
47#include <linux/module.h>
48#include <linux/moduleparam.h>
49#include <linux/types.h>
50#include <linux/timer.h>
51#include <linux/jiffies.h>
52#include <linux/miscdevice.h>
53#include <linux/watchdog.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
60#include <asm/io.h>
61#include <asm/uaccess.h>
62#include <asm/system.h>
63
64#define OUR_NAME "sbc60xxwdt"
65#define PFX OUR_NAME ": "
66
67/*
68 * You must set these - The driver cannot probe for the settings
69 */
70
71static int wdt_stop = 0x45;
72module_param(wdt_stop, int, 0);
73MODULE_PARM_DESC(wdt_stop, "SBC60xx WDT 'stop' io port (default 0x45)");
74
75static int wdt_start = 0x443;
76module_param(wdt_start, int, 0);
77MODULE_PARM_DESC(wdt_start, "SBC60xx WDT 'start' io port (default 0x443)");
78
79/*
80 * The 60xx board can use watchdog timeout values from one second
81 * to several minutes.  The default is one second, so if we reset
82 * the watchdog every ~250ms we should be safe.
83 */
84
85#define WDT_INTERVAL (HZ/4+1)
86
87/*
88 * We must not require too good response from the userspace daemon.
89 * Here we require the userspace daemon to send us a heartbeat
90 * char to /dev/watchdog every 30 seconds.
91 * If the daemon pulses us every 25 seconds, we can still afford
92 * a 5 second scheduling delay on the (high priority) daemon. That
93 * should be sufficient for a box under any load.
94 */
95
96#define WATCHDOG_TIMEOUT 30		/* 30 sec default timeout */
97static int timeout = WATCHDOG_TIMEOUT;	/* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
98module_param(timeout, int, 0);
99MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (1<=timeout<=3600, default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
100
101static int nowayout = WATCHDOG_NOWAYOUT;
102module_param(nowayout, int, 0);
103MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
104
105static void wdt_timer_ping(unsigned long);
106static DEFINE_TIMER(timer, wdt_timer_ping, 0, 0);
107static unsigned long next_heartbeat;
108static unsigned long wdt_is_open;
109static char wdt_expect_close;
110
111/*
112 *	Whack the dog
113 */
114
115static void wdt_timer_ping(unsigned long data)
116{
117	/* If we got a heartbeat pulse within the WDT_US_INTERVAL
118	 * we agree to ping the WDT
119	 */
120	if(time_before(jiffies, next_heartbeat))
121	{
122		/* Ping the WDT by reading from wdt_start */
123		inb_p(wdt_start);
124		/* Re-set the timer interval */
125		mod_timer(&timer, jiffies + WDT_INTERVAL);
126	} else {
127		printk(KERN_WARNING PFX "Heartbeat lost! Will not ping the watchdog\n");
128	}
129}
130
131/*
132 * Utility routines
133 */
134
135static void wdt_startup(void)
136{
137	next_heartbeat = jiffies + (timeout * HZ);
138
139	/* Start the timer */
140	mod_timer(&timer, jiffies + WDT_INTERVAL);
141	printk(KERN_INFO PFX "Watchdog timer is now enabled.\n");
142}
143
144static void wdt_turnoff(void)
145{
146	/* Stop the timer */
147	del_timer(&timer);
148	inb_p(wdt_stop);
149	printk(KERN_INFO PFX "Watchdog timer is now disabled...\n");
150}
151
152static void wdt_keepalive(void)
153{
154	/* user land ping */
155	next_heartbeat = jiffies + (timeout * HZ);
156}
157
158/*
159 * /dev/watchdog handling
160 */
161
162static ssize_t fop_write(struct file * file, const char __user * buf, size_t count, loff_t * ppos)
163{
164	/* See if we got the magic character 'V' and reload the timer */
165	if(count)
166	{
167		if (!nowayout)
168		{
169			size_t ofs;
170
171			/* note: just in case someone wrote the magic character
172			 * five months ago... */
173			wdt_expect_close = 0;
174
175			/* scan to see whether or not we got the magic character */
176			for(ofs = 0; ofs != count; ofs++)
177			{
178				char c;
179				if(get_user(c, buf+ofs))
180					return -EFAULT;
181				if(c == 'V')
182					wdt_expect_close = 42;
183			}
184		}
185
186		/* Well, anyhow someone wrote to us, we should return that favour */
187		wdt_keepalive();
188	}
189	return count;
190}
191
192static int fop_open(struct inode * inode, struct file * file)
193{
194	nonseekable_open(inode, file);
195
196	/* Just in case we're already talking to someone... */
197	if(test_and_set_bit(0, &wdt_is_open))
198		return -EBUSY;
199
200	if (nowayout)
201		__module_get(THIS_MODULE);
202
203	/* Good, fire up the show */
204	wdt_startup();
205	return 0;
206}
207
208static int fop_close(struct inode * inode, struct file * file)
209{
210	if(wdt_expect_close == 42)
211		wdt_turnoff();
212	else {
213		del_timer(&timer);
214		printk(KERN_CRIT PFX "device file closed unexpectedly. Will not stop the WDT!\n");
215	}
216	clear_bit(0, &wdt_is_open);
217	wdt_expect_close = 0;
218	return 0;
219}
220
221static int fop_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
222	unsigned long arg)
223{
224	void __user *argp = (void __user *)arg;
225	int __user *p = argp;
226	static struct watchdog_info ident=
227	{
228		.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
229		.firmware_version = 1,
230		.identity = "SBC60xx",
231	};
232
233	switch(cmd)
234	{
235		default:
236			return -ENOTTY;
237		case WDIOC_GETSUPPORT:
238			return copy_to_user(argp, &ident, sizeof(ident))?-EFAULT:0;
239		case WDIOC_GETSTATUS:
240		case WDIOC_GETBOOTSTATUS:
241			return put_user(0, p);
242		case WDIOC_KEEPALIVE:
243			wdt_keepalive();
244			return 0;
245		case WDIOC_SETOPTIONS:
246		{
247			int new_options, retval = -EINVAL;
248
249			if(get_user(new_options, p))
250				return -EFAULT;
251
252			if(new_options & WDIOS_DISABLECARD) {
253				wdt_turnoff();
254				retval = 0;
255			}
256
257			if(new_options & WDIOS_ENABLECARD) {
258				wdt_startup();
259				retval = 0;
260			}
261
262			return retval;
263		}
264		case WDIOC_SETTIMEOUT:
265		{
266			int new_timeout;
267
268			if(get_user(new_timeout, p))
269				return -EFAULT;
270
271			if(new_timeout < 1 || new_timeout > 3600) /* arbitrary upper limit */
272				return -EINVAL;
273
274			timeout = new_timeout;
275			wdt_keepalive();
276			/* Fall through */
277		}
278		case WDIOC_GETTIMEOUT:
279			return put_user(timeout, p);
280	}
281}
282
283static const struct file_operations wdt_fops = {
284	.owner		= THIS_MODULE,
285	.llseek		= no_llseek,
286	.write		= fop_write,
287	.open		= fop_open,
288	.release	= fop_close,
289	.ioctl		= fop_ioctl,
290};
291
292static struct miscdevice wdt_miscdev = {
293	.minor = WATCHDOG_MINOR,
294	.name = "watchdog",
295	.fops = &wdt_fops,
296};
297
298/*
299 *	Notifier for system down
300 */
301
302static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
303	void *unused)
304{
305	if(code==SYS_DOWN || code==SYS_HALT)
306		wdt_turnoff();
307	return NOTIFY_DONE;
308}
309
310/*
311 *	The WDT needs to learn about soft shutdowns in order to
312 *	turn the timebomb registers off.
313 */
314
315static struct notifier_block wdt_notifier=
316{
317	.notifier_call = wdt_notify_sys,
318};
319
320static void __exit sbc60xxwdt_unload(void)
321{
322	wdt_turnoff();
323
324	/* Deregister */
325	misc_deregister(&wdt_miscdev);
326
327	unregister_reboot_notifier(&wdt_notifier);
328	if ((wdt_stop != 0x45) && (wdt_stop != wdt_start))
329		release_region(wdt_stop,1);
330	release_region(wdt_start,1);
331}
332
333static int __init sbc60xxwdt_init(void)
334{
335	int rc = -EBUSY;
336
337	if(timeout < 1 || timeout > 3600) /* arbitrary upper limit */
338	{
339		timeout = WATCHDOG_TIMEOUT;
340		printk(KERN_INFO PFX "timeout value must be 1<=x<=3600, using %d\n",
341			timeout);
342 	}
343
344	if (!request_region(wdt_start, 1, "SBC 60XX WDT"))
345	{
346		printk(KERN_ERR PFX "I/O address 0x%04x already in use\n",
347			wdt_start);
348		rc = -EIO;
349		goto err_out;
350	}
351
352	/* We cannot reserve 0x45 - the kernel already has! */
353	if ((wdt_stop != 0x45) && (wdt_stop != wdt_start))
354	{
355		if (!request_region(wdt_stop, 1, "SBC 60XX WDT"))
356		{
357			printk(KERN_ERR PFX "I/O address 0x%04x already in use\n",
358				wdt_stop);
359			rc = -EIO;
360			goto err_out_region1;
361		}
362	}
363
364	rc = misc_register(&wdt_miscdev);
365	if (rc)
366	{
367		printk(KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n",
368			wdt_miscdev.minor, rc);
369		goto err_out_region2;
370	}
371
372	rc = register_reboot_notifier(&wdt_notifier);
373	if (rc)
374	{
375		printk(KERN_ERR PFX "cannot register reboot notifier (err=%d)\n",
376			rc);
377		goto err_out_miscdev;
378	}
379
380	printk(KERN_INFO PFX "WDT driver for 60XX single board computer initialised. timeout=%d sec (nowayout=%d)\n",
381		timeout, nowayout);
382
383	return 0;
384
385err_out_miscdev:
386	misc_deregister(&wdt_miscdev);
387err_out_region2:
388	if ((wdt_stop != 0x45) && (wdt_stop != wdt_start))
389		release_region(wdt_stop,1);
390err_out_region1:
391	release_region(wdt_start,1);
392err_out:
393	return rc;
394}
395
396module_init(sbc60xxwdt_init);
397module_exit(sbc60xxwdt_unload);
398
399MODULE_AUTHOR("Jakob Oestergaard <jakob@unthought.net>");
400MODULE_DESCRIPTION("60xx Single Board Computer Watchdog Timer driver");
401MODULE_LICENSE("GPL");
402MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
403