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>
69 #define OUR_NAME "sbc60xxwdt"
70 #define PFX OUR_NAME ": "
73 * You must set these - The driver cannot probe for the settings
76 static int wdt_stop
= 0x45;
77 module_param(wdt_stop
, int, 0);
78 MODULE_PARM_DESC(wdt_stop
, "SBC60xx WDT 'stop' io port (default 0x45)");
80 static int wdt_start
= 0x443;
81 module_param(wdt_start
, int, 0);
82 MODULE_PARM_DESC(wdt_start
, "SBC60xx WDT 'start' io port (default 0x443)");
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.
90 #define WDT_INTERVAL (HZ/4+1)
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.
101 #define WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */
102 static int timeout
= WATCHDOG_TIMEOUT
; /* in seconds, multiplied by HZ to
103 get seconds to wait for a ping */
104 module_param(timeout
, int, 0);
105 MODULE_PARM_DESC(timeout
,
106 "Watchdog timeout in seconds. (1<=timeout<=3600, default="
107 __MODULE_STRING(WATCHDOG_TIMEOUT
) ")");
109 static bool nowayout
= WATCHDOG_NOWAYOUT
;
110 module_param(nowayout
, bool, 0);
111 MODULE_PARM_DESC(nowayout
,
112 "Watchdog cannot be stopped once started (default="
113 __MODULE_STRING(WATCHDOG_NOWAYOUT
) ")");
115 static void wdt_timer_ping(unsigned long);
116 static DEFINE_TIMER(timer
, wdt_timer_ping
, 0, 0);
117 static unsigned long next_heartbeat
;
118 static unsigned long wdt_is_open
;
119 static char wdt_expect_close
;
125 static void wdt_timer_ping(unsigned long data
)
127 /* If we got a heartbeat pulse within the WDT_US_INTERVAL
128 * we agree to ping the WDT
130 if (time_before(jiffies
, next_heartbeat
)) {
131 /* Ping the WDT by reading from wdt_start */
133 /* Re-set the timer interval */
134 mod_timer(&timer
, jiffies
+ WDT_INTERVAL
);
136 pr_warn("Heartbeat lost! Will not ping the watchdog\n");
143 static void wdt_startup(void)
145 next_heartbeat
= jiffies
+ (timeout
* HZ
);
147 /* Start the timer */
148 mod_timer(&timer
, jiffies
+ WDT_INTERVAL
);
149 pr_info("Watchdog timer is now enabled\n");
152 static void wdt_turnoff(void)
157 pr_info("Watchdog timer is now disabled...\n");
160 static void wdt_keepalive(void)
163 next_heartbeat
= jiffies
+ (timeout
* HZ
);
167 * /dev/watchdog handling
170 static ssize_t
fop_write(struct file
*file
, const char __user
*buf
,
171 size_t count
, loff_t
*ppos
)
173 /* See if we got the magic character 'V' and reload the timer */
178 /* note: just in case someone wrote the
179 magic character five months ago... */
180 wdt_expect_close
= 0;
182 /* scan to see whether or not we got the
184 for (ofs
= 0; ofs
!= count
; ofs
++) {
186 if (get_user(c
, buf
+ ofs
))
189 wdt_expect_close
= 42;
193 /* Well, anyhow someone wrote to us, we should
194 return that favour */
200 static int fop_open(struct inode
*inode
, struct file
*file
)
202 /* Just in case we're already talking to someone... */
203 if (test_and_set_bit(0, &wdt_is_open
))
207 __module_get(THIS_MODULE
);
209 /* Good, fire up the show */
211 return nonseekable_open(inode
, file
);
214 static int fop_close(struct inode
*inode
, struct file
*file
)
216 if (wdt_expect_close
== 42)
220 pr_crit("device file closed unexpectedly. Will not stop the WDT!\n");
222 clear_bit(0, &wdt_is_open
);
223 wdt_expect_close
= 0;
227 static long fop_ioctl(struct file
*file
, unsigned int cmd
, unsigned long arg
)
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
|
234 .firmware_version
= 1,
235 .identity
= "SBC60xx",
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
:
246 int new_options
, retval
= -EINVAL
;
247 if (get_user(new_options
, p
))
249 if (new_options
& WDIOS_DISABLECARD
) {
253 if (new_options
& WDIOS_ENABLECARD
) {
259 case WDIOC_KEEPALIVE
:
262 case WDIOC_SETTIMEOUT
:
265 if (get_user(new_timeout
, p
))
267 /* arbitrary upper limit */
268 if (new_timeout
< 1 || new_timeout
> 3600)
271 timeout
= new_timeout
;
275 case WDIOC_GETTIMEOUT
:
276 return put_user(timeout
, p
);
282 static const struct file_operations wdt_fops
= {
283 .owner
= THIS_MODULE
,
287 .release
= fop_close
,
288 .unlocked_ioctl
= fop_ioctl
,
291 static struct miscdevice wdt_miscdev
= {
292 .minor
= WATCHDOG_MINOR
,
298 * Notifier for system down
301 static int wdt_notify_sys(struct notifier_block
*this, unsigned long code
,
304 if (code
== SYS_DOWN
|| code
== SYS_HALT
)
310 * The WDT needs to learn about soft shutdowns in order to
311 * turn the timebomb registers off.
314 static struct notifier_block wdt_notifier
= {
315 .notifier_call
= wdt_notify_sys
,
318 static void __exit
sbc60xxwdt_unload(void)
323 misc_deregister(&wdt_miscdev
);
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);
331 static int __init
sbc60xxwdt_init(void)
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",
341 if (!request_region(wdt_start
, 1, "SBC 60XX WDT")) {
342 pr_err("I/O address 0x%04x already in use\n", wdt_start
);
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
);
352 goto err_out_region1
;
356 rc
= register_reboot_notifier(&wdt_notifier
);
358 pr_err("cannot register reboot notifier (err=%d)\n", rc
);
359 goto err_out_region2
;
362 rc
= misc_register(&wdt_miscdev
);
364 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
365 wdt_miscdev
.minor
, rc
);
368 pr_info("WDT driver for 60XX single board computer initialised. timeout=%d sec (nowayout=%d)\n",
374 unregister_reboot_notifier(&wdt_notifier
);
376 if (wdt_stop
!= 0x45 && wdt_stop
!= wdt_start
)
377 release_region(wdt_stop
, 1);
379 release_region(wdt_start
, 1);
384 module_init(sbc60xxwdt_init
);
385 module_exit(sbc60xxwdt_unload
);
387 MODULE_AUTHOR("Jakob Oestergaard <jakob@unthought.net>");
388 MODULE_DESCRIPTION("60xx Single Board Computer Watchdog Timer driver");
389 MODULE_LICENSE("GPL");