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