2 * Acquire Single Board Computer Watchdog Timer driver
4 * Based on wdt.c. Original copyright messages:
6 * (c) Copyright 1996 Alan Cox <alan@redhat.com>, All Rights Reserved.
7 * http://www.redhat.com
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License
11 * as published by the Free Software Foundation; either version
12 * 2 of the License, or (at your option) any later version.
14 * Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
15 * warranty for any of this software. This material is provided
16 * "AS-IS" and at no charge.
18 * (c) Copyright 1995 Alan Cox <alan@redhat.com>
20 * 14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
21 * Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
22 * Can't add timeout - driver doesn't allow changing value
26 * Theory of Operation:
27 * The Watch-Dog Timer is provided to ensure that standalone
28 * Systems can always recover from catastrophic conditions that
29 * caused the CPU to crash. This condition may have occured by
30 * external EMI or a software bug. When the CPU stops working
31 * correctly, hardware on the board will either perform a hardware
32 * reset (cold boot) or a non-maskable interrupt (NMI) to bring the
33 * system back to a known state.
35 * The Watch-Dog Timer is controlled by two I/O Ports.
36 * 443 hex - Read - Enable or refresh the Watch-Dog Timer
37 * 043 hex - Read - Disable the Watch-Dog Timer
39 * To enable the Watch-Dog Timer, a read from I/O port 443h must
40 * be performed. This will enable and activate the countdown timer
41 * which will eventually time out and either reset the CPU or cause
42 * an NMI depending on the setting of a jumper. To ensure that this
43 * reset condition does not occur, the Watch-Dog Timer must be
44 * periodically refreshed by reading the same I/O port 443h.
45 * The Watch-Dog Timer is disabled by reading I/O port 043h.
47 * The Watch-Dog Timer Time-Out Period is set via jumpers.
48 * It can be 1, 2, 10, 20, 110 or 220 seconds.
52 * Includes, defines, variables, module parameters, ...
56 #include <linux/module.h> /* For module specific items */
57 #include <linux/moduleparam.h> /* For new moduleparam's */
58 #include <linux/types.h> /* For standard types (like size_t) */
59 #include <linux/errno.h> /* For the -ENODEV/... values */
60 #include <linux/kernel.h> /* For printk/panic/... */
61 #include <linux/miscdevice.h> /* For MODULE_ALIAS_MISCDEV
63 #include <linux/watchdog.h> /* For the watchdog specific items */
64 #include <linux/fs.h> /* For file operations */
65 #include <linux/ioport.h> /* For io-port access */
66 #include <linux/platform_device.h> /* For platform_driver framework */
67 #include <linux/init.h> /* For __init/__exit/... */
69 #include <linux/uaccess.h> /* For copy_to_user/put_user/... */
70 #include <linux/io.h> /* For inb/outb/... */
72 /* Module information */
73 #define DRV_NAME "acquirewdt"
74 #define PFX DRV_NAME ": "
75 #define WATCHDOG_NAME "Acquire WDT"
76 /* There is no way to see what the correct time-out period is */
77 #define WATCHDOG_HEARTBEAT 0
79 /* internal variables */
80 /* the watchdog platform device */
81 static struct platform_device *acq_platform_device;
82 static unsigned long acq_is_open;
83 static char expect_close;
85 /* module parameters */
86 /* You must set this - there is no sane way to probe for this board. */
87 static int wdt_stop = 0x43;
88 module_param(wdt_stop, int, 0);
89 MODULE_PARM_DESC(wdt_stop, "Acquire WDT 'stop' io port (default 0x43)");
91 /* You must set this - there is no sane way to probe for this board. */
92 static int wdt_start = 0x443;
93 module_param(wdt_start, int, 0);
94 MODULE_PARM_DESC(wdt_start, "Acquire WDT 'start' io port (default 0x443)");
96 static int nowayout = WATCHDOG_NOWAYOUT;
97 module_param(nowayout, int, 0);
98 MODULE_PARM_DESC(nowayout,
99 "Watchdog cannot be stopped once started (default="
100 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
103 * Watchdog Operations
106 static void acq_keepalive(void)
108 /* Write a watchdog value */
112 static void acq_stop(void)
114 /* Turn the card off */
119 * /dev/watchdog handling
122 static ssize_t acq_write(struct file *file, const char __user *buf,
123 size_t count, loff_t *ppos)
125 /* See if we got the magic character 'V' and reload the timer */
129 /* note: just in case someone wrote the magic character
130 * five months ago... */
132 /* scan to see whether or not we got the
134 for (i = 0; i != count; i++) {
136 if (get_user(c, buf + i))
142 /* Well, anyhow someone wrote to us, we should
143 return that favour */
149 static long acq_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
151 int options, retval = -EINVAL;
152 void __user *argp = (void __user *)arg;
153 int __user *p = argp;
154 static struct watchdog_info ident = {
155 .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
156 .firmware_version = 1,
157 .identity = WATCHDOG_NAME,
161 case WDIOC_GETSUPPORT:
162 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
164 case WDIOC_GETSTATUS:
165 case WDIOC_GETBOOTSTATUS:
166 return put_user(0, p);
168 case WDIOC_KEEPALIVE:
172 case WDIOC_GETTIMEOUT:
173 return put_user(WATCHDOG_HEARTBEAT, p);
175 case WDIOC_SETOPTIONS:
177 if (get_user(options, p))
179 if (options & WDIOS_DISABLECARD) {
183 if (options & WDIOS_ENABLECARD) {
194 static int acq_open(struct inode *inode, struct file *file)
196 if (test_and_set_bit(0, &acq_is_open))
200 __module_get(THIS_MODULE);
204 return nonseekable_open(inode, file);
207 static int acq_close(struct inode *inode, struct file *file)
209 if (expect_close == 42) {
213 "Unexpected close, not stopping watchdog!\n");
216 clear_bit(0, &acq_is_open);
225 static const struct file_operations acq_fops = {
226 .owner = THIS_MODULE,
229 .unlocked_ioctl = acq_ioctl,
231 .release = acq_close,
234 static struct miscdevice acq_miscdev = {
235 .minor = WATCHDOG_MINOR,
241 * Init & exit routines
244 static int __devinit acq_probe(struct platform_device *dev)
248 if (wdt_stop != wdt_start) {
249 if (!request_region(wdt_stop, 1, WATCHDOG_NAME)) {
251 "I/O address 0x%04x already in use\n", wdt_stop);
257 if (!request_region(wdt_start, 1, WATCHDOG_NAME)) {
258 printk(KERN_ERR PFX "I/O address 0x%04x already in use\n",
263 ret = misc_register(&acq_miscdev);
266 "cannot register miscdev on minor=%d (err=%d)\n",
267 WATCHDOG_MINOR, ret);
270 printk(KERN_INFO PFX "initialized. (nowayout=%d)\n", nowayout);
274 release_region(wdt_start, 1);
276 if (wdt_stop != wdt_start)
277 release_region(wdt_stop, 1);
282 static int __devexit acq_remove(struct platform_device *dev)
284 misc_deregister(&acq_miscdev);
285 release_region(wdt_start, 1);
286 if (wdt_stop != wdt_start)
287 release_region(wdt_stop, 1);
292 static void acq_shutdown(struct platform_device *dev)
294 /* Turn the WDT off if we have a soft shutdown */
298 static struct platform_driver acquirewdt_driver = {
300 .remove = __devexit_p(acq_remove),
301 .shutdown = acq_shutdown,
303 .owner = THIS_MODULE,
308 static int __init acq_init(void)
313 "WDT driver for Acquire single board computer initialising.\n");
315 err = platform_driver_register(&acquirewdt_driver);
319 acq_platform_device = platform_device_register_simple(DRV_NAME,
321 if (IS_ERR(acq_platform_device)) {
322 err = PTR_ERR(acq_platform_device);
323 goto unreg_platform_driver;
327 unreg_platform_driver:
328 platform_driver_unregister(&acquirewdt_driver);
332 static void __exit acq_exit(void)
334 platform_device_unregister(acq_platform_device);
335 platform_driver_unregister(&acquirewdt_driver);
336 printk(KERN_INFO PFX "Watchdog Module Unloaded.\n");
339 module_init(acq_init);
340 module_exit(acq_exit);
342 MODULE_AUTHOR("David Woodhouse");
343 MODULE_DESCRIPTION("Acquire Inc. Single Board Computer Watchdog Timer driver");
344 MODULE_LICENSE("GPL");
345 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);