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"
20 *					on success
21 *           12/4 - 2002      [rob@osinvestor.com] eliminate fop_read
22 *                            fix possible wdt_is_open race
23 *                            add CONFIG_WATCHDOG_NOWAYOUT support
24 *                            remove lock_kernel/unlock_kernel pairs
25 *                            added KERN_* to printk's
26 *                            got rid of extraneous comments
27 *                            changed watchdog_info to correctly reflect what
28 *			      the driver offers
29 *			      added WDIOC_GETSTATUS, WDIOC_GETBOOTSTATUS,
30 *			      WDIOC_SETTIMEOUT, WDIOC_GETTIMEOUT, and
31 *			      WDIOC_SETOPTIONS ioctls
32 *           09/8 - 2003      [wim@iguana.be] cleanup of trailing spaces
33 *                            use module_param
34 *                            made timeout (the emulated heartbeat) a
35 *			      module_param
36 *                            made the keepalive ping an internal subroutine
37 *                            made wdt_stop and wdt_start module params
38 *                            added extra printk's for startup problems
39 *                            added MODULE_AUTHOR and MODULE_DESCRIPTION info
40 *
41 *
42 *  This WDT driver is different from the other Linux WDT
43 *  drivers in the following ways:
44 *  *)  The driver will ping the watchdog by itself, because this
45 *      particular WDT has a very short timeout (one second) and it
46 *      would be insane to count on any userspace daemon always
47 *      getting scheduled within that time frame.
48 *
49 */
50
51#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
52
53#include <linux/module.h>
54#include <linux/moduleparam.h>
55#include <linux/types.h>
56#include <linux/timer.h>
57#include <linux/jiffies.h>
58#include <linux/miscdevice.h>
59#include <linux/watchdog.h>
60#include <linux/fs.h>
61#include <linux/ioport.h>
62#include <linux/notifier.h>
63#include <linux/reboot.h>
64#include <linux/init.h>
65#include <linux/io.h>
66#include <linux/uaccess.h>
67
68
69#define OUR_NAME "sbc60xxwdt"
70#define PFX OUR_NAME ": "
71
72/*
73 * You must set these - The driver cannot probe for the settings
74 */
75
76static int wdt_stop = 0x45;
77module_param(wdt_stop, int, 0);
78MODULE_PARM_DESC(wdt_stop, "SBC60xx WDT 'stop' io port (default 0x45)");
79
80static int wdt_start = 0x443;
81module_param(wdt_start, int, 0);
82MODULE_PARM_DESC(wdt_start, "SBC60xx WDT 'start' io port (default 0x443)");
83
84/*
85 * The 60xx board can use watchdog timeout values from one second
86 * to several minutes.  The default is one second, so if we reset
87 * the watchdog every ~250ms we should be safe.
88 */
89
90#define WDT_INTERVAL (HZ/4+1)
91
92/*
93 * We must not require too good response from the userspace daemon.
94 * Here we require the userspace daemon to send us a heartbeat
95 * char to /dev/watchdog every 30 seconds.
96 * If the daemon pulses us every 25 seconds, we can still afford
97 * a 5 second scheduling delay on the (high priority) daemon. That
98 * should be sufficient for a box under any load.
99 */
100
101#define WATCHDOG_TIMEOUT 30		/* 30 sec default timeout */
102static int timeout = WATCHDOG_TIMEOUT;	/* in seconds, multiplied by HZ to
103					   get seconds to wait for a ping */
104module_param(timeout, int, 0);
105MODULE_PARM_DESC(timeout,
106	"Watchdog timeout in seconds. (1<=timeout<=3600, default="
107				__MODULE_STRING(WATCHDOG_TIMEOUT) ")");
108
109static bool nowayout = WATCHDOG_NOWAYOUT;
110module_param(nowayout, bool, 0);
111MODULE_PARM_DESC(nowayout,
112	"Watchdog cannot be stopped once started (default="
113				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
114
115static void wdt_timer_ping(unsigned long);
116static DEFINE_TIMER(timer, wdt_timer_ping, 0, 0);
117static unsigned long next_heartbeat;
118static unsigned long wdt_is_open;
119static char wdt_expect_close;
120
121/*
122 *	Whack the dog
123 */
124
125static void wdt_timer_ping(unsigned long data)
126{
127	/* If we got a heartbeat pulse within the WDT_US_INTERVAL
128	 * we agree to ping the WDT
129	 */
130	if (time_before(jiffies, next_heartbeat)) {
131		/* Ping the WDT by reading from wdt_start */
132		inb_p(wdt_start);
133		/* Re-set the timer interval */
134		mod_timer(&timer, jiffies + WDT_INTERVAL);
135	} else
136		pr_warn("Heartbeat lost! Will not ping the watchdog\n");
137}
138
139/*
140 * Utility routines
141 */
142
143static void wdt_startup(void)
144{
145	next_heartbeat = jiffies + (timeout * HZ);
146
147	/* Start the timer */
148	mod_timer(&timer, jiffies + WDT_INTERVAL);
149	pr_info("Watchdog timer is now enabled\n");
150}
151
152static void wdt_turnoff(void)
153{
154	/* Stop the timer */
155	del_timer(&timer);
156	inb_p(wdt_stop);
157	pr_info("Watchdog timer is now disabled...\n");
158}
159
160static void wdt_keepalive(void)
161{
162	/* user land ping */
163	next_heartbeat = jiffies + (timeout * HZ);
164}
165
166/*
167 * /dev/watchdog handling
168 */
169
170static ssize_t fop_write(struct file *file, const char __user *buf,
171						size_t count, loff_t *ppos)
172{
173	/* See if we got the magic character 'V' and reload the timer */
174	if (count) {
175		if (!nowayout) {
176			size_t ofs;
177
178			/* note: just in case someone wrote the
179			   magic character five months ago... */
180			wdt_expect_close = 0;
181
182			/* scan to see whether or not we got the
183			   magic character */
184			for (ofs = 0; ofs != count; ofs++) {
185				char c;
186				if (get_user(c, buf + ofs))
187					return -EFAULT;
188				if (c == 'V')
189					wdt_expect_close = 42;
190			}
191		}
192
193		/* Well, anyhow someone wrote to us, we should
194		   return that favour */
195		wdt_keepalive();
196	}
197	return count;
198}
199
200static int fop_open(struct inode *inode, struct file *file)
201{
202	/* Just in case we're already talking to someone... */
203	if (test_and_set_bit(0, &wdt_is_open))
204		return -EBUSY;
205
206	if (nowayout)
207		__module_get(THIS_MODULE);
208
209	/* Good, fire up the show */
210	wdt_startup();
211	return nonseekable_open(inode, file);
212}
213
214static int fop_close(struct inode *inode, struct file *file)
215{
216	if (wdt_expect_close == 42)
217		wdt_turnoff();
218	else {
219		del_timer(&timer);
220		pr_crit("device file closed unexpectedly. Will not stop the WDT!\n");
221	}
222	clear_bit(0, &wdt_is_open);
223	wdt_expect_close = 0;
224	return 0;
225}
226
227static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
228{
229	void __user *argp = (void __user *)arg;
230	int __user *p = argp;
231	static const struct watchdog_info ident = {
232		.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
233							WDIOF_MAGICCLOSE,
234		.firmware_version = 1,
235		.identity = "SBC60xx",
236	};
237
238	switch (cmd) {
239	case WDIOC_GETSUPPORT:
240		return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
241	case WDIOC_GETSTATUS:
242	case WDIOC_GETBOOTSTATUS:
243		return put_user(0, p);
244	case WDIOC_SETOPTIONS:
245	{
246		int new_options, retval = -EINVAL;
247		if (get_user(new_options, p))
248			return -EFAULT;
249		if (new_options & WDIOS_DISABLECARD) {
250			wdt_turnoff();
251			retval = 0;
252		}
253		if (new_options & WDIOS_ENABLECARD) {
254			wdt_startup();
255			retval = 0;
256		}
257		return retval;
258	}
259	case WDIOC_KEEPALIVE:
260		wdt_keepalive();
261		return 0;
262	case WDIOC_SETTIMEOUT:
263	{
264		int new_timeout;
265		if (get_user(new_timeout, p))
266			return -EFAULT;
267		/* arbitrary upper limit */
268		if (new_timeout < 1 || new_timeout > 3600)
269			return -EINVAL;
270
271		timeout = new_timeout;
272		wdt_keepalive();
273		/* Fall through */
274	}
275	case WDIOC_GETTIMEOUT:
276		return put_user(timeout, p);
277	default:
278		return -ENOTTY;
279	}
280}
281
282static const struct file_operations wdt_fops = {
283	.owner		= THIS_MODULE,
284	.llseek		= no_llseek,
285	.write		= fop_write,
286	.open		= fop_open,
287	.release	= fop_close,
288	.unlocked_ioctl	= fop_ioctl,
289};
290
291static struct miscdevice wdt_miscdev = {
292	.minor = WATCHDOG_MINOR,
293	.name = "watchdog",
294	.fops = &wdt_fops,
295};
296
297/*
298 *	Notifier for system down
299 */
300
301static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
302	void *unused)
303{
304	if (code == SYS_DOWN || code == SYS_HALT)
305		wdt_turnoff();
306	return NOTIFY_DONE;
307}
308
309/*
310 *	The WDT needs to learn about soft shutdowns in order to
311 *	turn the timebomb registers off.
312 */
313
314static struct notifier_block wdt_notifier = {
315	.notifier_call = wdt_notify_sys,
316};
317
318static void __exit sbc60xxwdt_unload(void)
319{
320	wdt_turnoff();
321
322	/* Deregister */
323	misc_deregister(&wdt_miscdev);
324
325	unregister_reboot_notifier(&wdt_notifier);
326	if ((wdt_stop != 0x45) && (wdt_stop != wdt_start))
327		release_region(wdt_stop, 1);
328	release_region(wdt_start, 1);
329}
330
331static int __init sbc60xxwdt_init(void)
332{
333	int rc = -EBUSY;
334
335	if (timeout < 1 || timeout > 3600) { /* arbitrary upper limit */
336		timeout = WATCHDOG_TIMEOUT;
337		pr_info("timeout value must be 1 <= x <= 3600, using %d\n",
338			timeout);
339	}
340
341	if (!request_region(wdt_start, 1, "SBC 60XX WDT")) {
342		pr_err("I/O address 0x%04x already in use\n", wdt_start);
343		rc = -EIO;
344		goto err_out;
345	}
346
347	/* We cannot reserve 0x45 - the kernel already has! */
348	if (wdt_stop != 0x45 && wdt_stop != wdt_start) {
349		if (!request_region(wdt_stop, 1, "SBC 60XX WDT")) {
350			pr_err("I/O address 0x%04x already in use\n", wdt_stop);
351			rc = -EIO;
352			goto err_out_region1;
353		}
354	}
355
356	rc = register_reboot_notifier(&wdt_notifier);
357	if (rc) {
358		pr_err("cannot register reboot notifier (err=%d)\n", rc);
359		goto err_out_region2;
360	}
361
362	rc = misc_register(&wdt_miscdev);
363	if (rc) {
364		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
365		       wdt_miscdev.minor, rc);
366		goto err_out_reboot;
367	}
368	pr_info("WDT driver for 60XX single board computer initialised. timeout=%d sec (nowayout=%d)\n",
369		timeout, nowayout);
370
371	return 0;
372
373err_out_reboot:
374	unregister_reboot_notifier(&wdt_notifier);
375err_out_region2:
376	if (wdt_stop != 0x45 && wdt_stop != wdt_start)
377		release_region(wdt_stop, 1);
378err_out_region1:
379	release_region(wdt_start, 1);
380err_out:
381	return rc;
382}
383
384module_init(sbc60xxwdt_init);
385module_exit(sbc60xxwdt_unload);
386
387MODULE_AUTHOR("Jakob Oestergaard <jakob@unthought.net>");
388MODULE_DESCRIPTION("60xx Single Board Computer Watchdog Timer driver");
389MODULE_LICENSE("GPL");
390