2 * 60xx Single Board Computer Watchdog Timer driver for Linux 2.2.x
4 * Based on acquirewdt.c by Alan Cox.
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.
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.
15 * (c) Copyright 2000 Jakob Oestergaard <jakob@unthought.net>
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"
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
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
34 * made timeout (the emulated heartbeat) a
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
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.
51 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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>
61 #include <linux/ioport.h>
62 #include <linux/notifier.h>
63 #include <linux/reboot.h>
64 #include <linux/init.h>
66 #include <linux/uaccess.h>
68 #include <asm/system.h>
70 #define OUR_NAME "sbc60xxwdt"
71 #define PFX OUR_NAME ": "
74 * You must set these - The driver cannot probe for the settings
77 static int wdt_stop = 0x45;
78 module_param(wdt_stop, int, 0);
79 MODULE_PARM_DESC(wdt_stop, "SBC60xx WDT 'stop' io port (default 0x45)");
81 static int wdt_start = 0x443;
82 module_param(wdt_start, int, 0);
83 MODULE_PARM_DESC(wdt_start, "SBC60xx WDT 'start' io port (default 0x443)");
86 * The 60xx board can use watchdog timeout values from one second
87 * to several minutes. The default is one second, so if we reset
88 * the watchdog every ~250ms we should be safe.
91 #define WDT_INTERVAL (HZ/4+1)
94 * We must not require too good response from the userspace daemon.
95 * Here we require the userspace daemon to send us a heartbeat
96 * char to /dev/watchdog every 30 seconds.
97 * If the daemon pulses us every 25 seconds, we can still afford
98 * a 5 second scheduling delay on the (high priority) daemon. That
99 * should be sufficient for a box under any load.
102 #define WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */
103 static int timeout = WATCHDOG_TIMEOUT; /* in seconds, multiplied by HZ to
104 get seconds to wait for a ping */
105 module_param(timeout, int, 0);
106 MODULE_PARM_DESC(timeout,
107 "Watchdog timeout in seconds. (1<=timeout<=3600, default="
108 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
110 static bool nowayout = WATCHDOG_NOWAYOUT;
111 module_param(nowayout, bool, 0);
112 MODULE_PARM_DESC(nowayout,
113 "Watchdog cannot be stopped once started (default="
114 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
116 static void wdt_timer_ping(unsigned long);
117 static DEFINE_TIMER(timer, wdt_timer_ping, 0, 0);
118 static unsigned long next_heartbeat;
119 static unsigned long wdt_is_open;
120 static char wdt_expect_close;
126 static void wdt_timer_ping(unsigned long data)
128 /* If we got a heartbeat pulse within the WDT_US_INTERVAL
129 * we agree to ping the WDT
131 if (time_before(jiffies, next_heartbeat)) {
132 /* Ping the WDT by reading from wdt_start */
134 /* Re-set the timer interval */
135 mod_timer(&timer, jiffies + WDT_INTERVAL);
137 pr_warn("Heartbeat lost! Will not ping the watchdog\n");
144 static void wdt_startup(void)
146 next_heartbeat = jiffies + (timeout * HZ);
148 /* Start the timer */
149 mod_timer(&timer, jiffies + WDT_INTERVAL);
150 pr_info("Watchdog timer is now enabled\n");
153 static void wdt_turnoff(void)
158 pr_info("Watchdog timer is now disabled...\n");
161 static void wdt_keepalive(void)
164 next_heartbeat = jiffies + (timeout * HZ);
168 * /dev/watchdog handling
171 static ssize_t fop_write(struct file *file, const char __user *buf,
172 size_t count, loff_t *ppos)
174 /* See if we got the magic character 'V' and reload the timer */
179 /* note: just in case someone wrote the
180 magic character five months ago... */
181 wdt_expect_close = 0;
183 /* scan to see whether or not we got the
185 for (ofs = 0; ofs != count; ofs++) {
187 if (get_user(c, buf + ofs))
190 wdt_expect_close = 42;
194 /* Well, anyhow someone wrote to us, we should
195 return that favour */
201 static int fop_open(struct inode *inode, struct file *file)
203 /* Just in case we're already talking to someone... */
204 if (test_and_set_bit(0, &wdt_is_open))
208 __module_get(THIS_MODULE);
210 /* Good, fire up the show */
212 return nonseekable_open(inode, file);
215 static int fop_close(struct inode *inode, struct file *file)
217 if (wdt_expect_close == 42)
221 pr_crit("device file closed unexpectedly. Will not stop the WDT!\n");
223 clear_bit(0, &wdt_is_open);
224 wdt_expect_close = 0;
228 static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
230 void __user *argp = (void __user *)arg;
231 int __user *p = argp;
232 static const struct watchdog_info ident = {
233 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
235 .firmware_version = 1,
236 .identity = "SBC60xx",
240 case WDIOC_GETSUPPORT:
241 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
242 case WDIOC_GETSTATUS:
243 case WDIOC_GETBOOTSTATUS:
244 return put_user(0, p);
245 case WDIOC_SETOPTIONS:
247 int new_options, retval = -EINVAL;
248 if (get_user(new_options, p))
250 if (new_options & WDIOS_DISABLECARD) {
254 if (new_options & WDIOS_ENABLECARD) {
260 case WDIOC_KEEPALIVE:
263 case WDIOC_SETTIMEOUT:
266 if (get_user(new_timeout, p))
268 /* arbitrary upper limit */
269 if (new_timeout < 1 || new_timeout > 3600)
272 timeout = new_timeout;
276 case WDIOC_GETTIMEOUT:
277 return put_user(timeout, p);
283 static const struct file_operations wdt_fops = {
284 .owner = THIS_MODULE,
288 .release = fop_close,
289 .unlocked_ioctl = fop_ioctl,
292 static struct miscdevice wdt_miscdev = {
293 .minor = WATCHDOG_MINOR,
299 * Notifier for system down
302 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
305 if (code == SYS_DOWN || code == SYS_HALT)
311 * The WDT needs to learn about soft shutdowns in order to
312 * turn the timebomb registers off.
315 static struct notifier_block wdt_notifier = {
316 .notifier_call = wdt_notify_sys,
319 static void __exit sbc60xxwdt_unload(void)
324 misc_deregister(&wdt_miscdev);
326 unregister_reboot_notifier(&wdt_notifier);
327 if ((wdt_stop != 0x45) && (wdt_stop != wdt_start))
328 release_region(wdt_stop, 1);
329 release_region(wdt_start, 1);
332 static int __init sbc60xxwdt_init(void)
336 if (timeout < 1 || timeout > 3600) { /* arbitrary upper limit */
337 timeout = WATCHDOG_TIMEOUT;
338 pr_info("timeout value must be 1 <= x <= 3600, using %d\n",
342 if (!request_region(wdt_start, 1, "SBC 60XX WDT")) {
343 pr_err("I/O address 0x%04x already in use\n", wdt_start);
348 /* We cannot reserve 0x45 - the kernel already has! */
349 if (wdt_stop != 0x45 && wdt_stop != wdt_start) {
350 if (!request_region(wdt_stop, 1, "SBC 60XX WDT")) {
351 pr_err("I/O address 0x%04x already in use\n", wdt_stop);
353 goto err_out_region1;
357 rc = register_reboot_notifier(&wdt_notifier);
359 pr_err("cannot register reboot notifier (err=%d)\n", rc);
360 goto err_out_region2;
363 rc = misc_register(&wdt_miscdev);
365 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
366 wdt_miscdev.minor, rc);
369 pr_info("WDT driver for 60XX single board computer initialised. timeout=%d sec (nowayout=%d)\n",
375 unregister_reboot_notifier(&wdt_notifier);
377 if (wdt_stop != 0x45 && wdt_stop != wdt_start)
378 release_region(wdt_stop, 1);
380 release_region(wdt_start, 1);
385 module_init(sbc60xxwdt_init);
386 module_exit(sbc60xxwdt_unload);
388 MODULE_AUTHOR("Jakob Oestergaard <jakob@unthought.net>");
389 MODULE_DESCRIPTION("60xx Single Board Computer Watchdog Timer driver");
390 MODULE_LICENSE("GPL");
391 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);