1 /*
2 * IB700 Single Board Computer WDT driver for Linux 2.4.x
3 *
4 * (c) Copyright 2001 Charles Howes <chowes@vsol.net>
5 *
6 * Based on advantechwdt.c which is based on acquirewdt.c which
7 * is based on wdt.c.
8 *
9 * (c) Copyright 2000-2001 Marek Michalkiewicz <marekm@linux.org.pl>
10 *
11 * Based on acquirewdt.c which is based on wdt.c.
12 * Original copyright messages:
13 *
14 * (c) Copyright 1996 Alan Cox <alan@redhat.com>, All Rights Reserved.
15 * http://www.redhat.com
16 *
17 * This program is free software; you can redistribute it and/or
18 * modify it under the terms of the GNU General Public License
19 * as published by the Free Software Foundation; either version
20 * 2 of the License, or (at your option) any later version.
21 *
22 * Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
23 * warranty for any of this software. This material is provided
24 * "AS-IS" and at no charge.
25 *
26 * (c) Copyright 1995 Alan Cox <alan@redhat.com>
27 *
28 */
29
30 #include <linux/config.h>
31 #include <linux/module.h>
32 #include <linux/version.h>
33 #include <linux/types.h>
34 #include <linux/errno.h>
35 #include <linux/kernel.h>
36 #include <linux/sched.h>
37 #include <linux/miscdevice.h>
38 #include <linux/watchdog.h>
39 #include <linux/slab.h>
40 #include <linux/ioport.h>
41 #include <linux/fcntl.h>
42 #include <asm/io.h>
43 #include <asm/uaccess.h>
44 #include <asm/system.h>
45 #include <linux/notifier.h>
46 #include <linux/reboot.h>
47 #include <linux/init.h>
48 #include <linux/spinlock.h>
49 #include <linux/smp_lock.h>
50
51 static int ibwdt_is_open;
52 static spinlock_t ibwdt_lock;
53 static int expect_close = 0;
54
55 /*
56 *
57 * Watchdog Timer Configuration
58 *
59 * The function of the watchdog timer is to reset the system
60 * automatically and is defined at I/O port 0443H. To enable the
61 * watchdog timer and allow the system to reset, write I/O port 0443H.
62 * To disable the timer, write I/O port 0441H for the system to stop the
63 * watchdog function. The timer has a tolerance of 20% for its
64 * intervals.
65 *
66 * The following describes how the timer should be programmed.
67 *
68 * Enabling Watchdog:
69 * MOV AX,000FH (Choose the values from 0 to F)
70 * MOV DX,0443H
71 * OUT DX,AX
72 *
73 * Disabling Watchdog:
74 * MOV AX,000FH (Any value is fine.)
75 * MOV DX,0441H
76 * OUT DX,AX
77 *
78 * Watchdog timer control table:
79 * Level Value Time/sec | Level Value Time/sec
80 * 1 F 0 | 9 7 16
81 * 2 E 2 | 10 6 18
82 * 3 D 4 | 11 5 20
83 * 4 C 6 | 12 4 22
84 * 5 B 8 | 13 3 24
85 * 6 A 10 | 14 2 26
86 * 7 9 12 | 15 1 28
87 * 8 8 14 | 16 0 30
88 *
89 */
90
91 static int wd_times[] = {
92 30, /* 0x0 */
93 28, /* 0x1 */
94 26, /* 0x2 */
95 24, /* 0x3 */
96 22, /* 0x4 */
97 20, /* 0x5 */
98 18, /* 0x6 */
99 16, /* 0x7 */
100 14, /* 0x8 */
101 12, /* 0x9 */
102 10, /* 0xA */
103 8, /* 0xB */
104 6, /* 0xC */
105 4, /* 0xD */
106 2, /* 0xE */
107 0, /* 0xF */
108 };
109
110 #define WDT_STOP 0x441
111 #define WDT_START 0x443
112
113 /* Default timeout */
114 #define WD_TIMO 0 /* 30 seconds +/- 20%, from table */
115
116 static int wd_margin = WD_TIMO;
117
118 #ifdef CONFIG_WATCHDOG_NOWAYOUT
119 static int nowayout = 1;
120 #else
121 static int nowayout = 0;
122 #endif
123
124 MODULE_PARM(nowayout,"i");
125 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_WATCHDOG_NOWAYOUT)");
126
127
128 /*
129 * Kernel methods.
130 */
131
132 static void
ibwdt_ping(void)133 ibwdt_ping(void)
134 {
135 /* Write a watchdog value */
136 outb_p(wd_margin, WDT_START);
137 }
138
139 static ssize_t
ibwdt_write(struct file * file,const char * buf,size_t count,loff_t * ppos)140 ibwdt_write(struct file *file, const char *buf, size_t count, loff_t *ppos)
141 {
142 /* Can't seek (pwrite) on this device */
143 if (ppos != &file->f_pos)
144 return -ESPIPE;
145
146 if (count) {
147 if (!nowayout) {
148 size_t i;
149
150 /* In case it was set long ago */
151 expect_close = 0;
152
153 for (i = 0; i != count; i++) {
154 char c;
155 if (get_user(c, buf + i))
156 return -EFAULT;
157 if (c == 'V')
158 expect_close = 1;
159 }
160 }
161 ibwdt_ping();
162 return 1;
163 }
164 return 0;
165 }
166
167 static ssize_t
ibwdt_read(struct file * file,char * buf,size_t count,loff_t * ppos)168 ibwdt_read(struct file *file, char *buf, size_t count, loff_t *ppos)
169 {
170 return -EINVAL;
171 }
172
173 static int
ibwdt_ioctl(struct inode * inode,struct file * file,unsigned int cmd,unsigned long arg)174 ibwdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
175 unsigned long arg)
176 {
177 int i, new_margin;
178
179 static struct watchdog_info ident = {
180 WDIOF_KEEPALIVEPING |
181 WDIOF_SETTIMEOUT |
182 WDIOF_MAGICCLOSE,
183 1, "IB700 WDT"
184 };
185
186 switch (cmd) {
187 case WDIOC_GETSUPPORT:
188 if (copy_to_user((struct watchdog_info *)arg, &ident, sizeof(ident)))
189 return -EFAULT;
190 break;
191
192 case WDIOC_GETSTATUS:
193 if (copy_to_user((int *)arg, &ibwdt_is_open, sizeof(int)))
194 return -EFAULT;
195 break;
196
197 case WDIOC_KEEPALIVE:
198 ibwdt_ping();
199 break;
200
201 case WDIOC_SETTIMEOUT:
202 if (get_user(new_margin, (int *)arg))
203 return -EFAULT;
204 if ((new_margin < 0) || (new_margin > 30))
205 return -EINVAL;
206 for (i = 0x0F; i > -1; i--)
207 if (wd_times[i] > new_margin)
208 break;
209 wd_margin = i;
210 ibwdt_ping();
211 /* Fall */
212
213 case WDIOC_GETTIMEOUT:
214 return put_user(wd_times[wd_margin], (int *)arg);
215 break;
216
217 default:
218 return -ENOTTY;
219 }
220 return 0;
221 }
222
223 static int
ibwdt_open(struct inode * inode,struct file * file)224 ibwdt_open(struct inode *inode, struct file *file)
225 {
226 switch (MINOR(inode->i_rdev)) {
227 case WATCHDOG_MINOR:
228 spin_lock(&ibwdt_lock);
229 if (ibwdt_is_open) {
230 spin_unlock(&ibwdt_lock);
231 return -EBUSY;
232 }
233 /*
234 * Activate
235 */
236
237 ibwdt_is_open = 1;
238 ibwdt_ping();
239 spin_unlock(&ibwdt_lock);
240 return 0;
241 default:
242 return -ENODEV;
243 }
244 }
245
246 static int
ibwdt_close(struct inode * inode,struct file * file)247 ibwdt_close(struct inode *inode, struct file *file)
248 {
249 lock_kernel();
250 if (MINOR(inode->i_rdev) == WATCHDOG_MINOR) {
251 spin_lock(&ibwdt_lock);
252 if (expect_close) {
253 outb_p(wd_times[wd_margin], WDT_STOP);
254 } else {
255 printk(KERN_CRIT "WDT device closed unexpectedly. WDT will not stop!\n");
256 }
257 ibwdt_is_open = 0;
258 spin_unlock(&ibwdt_lock);
259 }
260 unlock_kernel();
261 return 0;
262 }
263
264 /*
265 * Notifier for system down
266 */
267
268 static int
ibwdt_notify_sys(struct notifier_block * this,unsigned long code,void * unused)269 ibwdt_notify_sys(struct notifier_block *this, unsigned long code,
270 void *unused)
271 {
272 if (code == SYS_DOWN || code == SYS_HALT) {
273 /* Turn the WDT off */
274 outb_p(wd_times[wd_margin], WDT_STOP);
275 }
276 return NOTIFY_DONE;
277 }
278
279 /*
280 * Kernel Interfaces
281 */
282
283 static struct file_operations ibwdt_fops = {
284 owner: THIS_MODULE,
285 read: ibwdt_read,
286 write: ibwdt_write,
287 ioctl: ibwdt_ioctl,
288 open: ibwdt_open,
289 release: ibwdt_close,
290 };
291
292 static struct miscdevice ibwdt_miscdev = {
293 WATCHDOG_MINOR,
294 "watchdog",
295 &ibwdt_fops
296 };
297
298 /*
299 * The WDT needs to learn about soft shutdowns in order to
300 * turn the timebomb registers off.
301 */
302
303 static struct notifier_block ibwdt_notifier = {
304 ibwdt_notify_sys,
305 NULL,
306 0
307 };
308
309 static int __init
ibwdt_init(void)310 ibwdt_init(void)
311 {
312 printk("WDT driver for IB700 single board computer initialising.\n");
313
314 spin_lock_init(&ibwdt_lock);
315 misc_register(&ibwdt_miscdev);
316 #if WDT_START != WDT_STOP
317 request_region(WDT_STOP, 1, "IB700 WDT");
318 #endif
319 request_region(WDT_START, 1, "IB700 WDT");
320 register_reboot_notifier(&ibwdt_notifier);
321 return 0;
322 }
323
324 static void __exit
ibwdt_exit(void)325 ibwdt_exit(void)
326 {
327 misc_deregister(&ibwdt_miscdev);
328 unregister_reboot_notifier(&ibwdt_notifier);
329 #if WDT_START != WDT_STOP
330 release_region(WDT_STOP,1);
331 #endif
332 release_region(WDT_START,1);
333 }
334
335 module_init(ibwdt_init);
336 module_exit(ibwdt_exit);
337
338 MODULE_AUTHOR("Charles Howes <chowes@vsol.net>");
339 MODULE_DESCRIPTION("IB700 SBC watchdog driver");
340 MODULE_LICENSE("GPL");
341
342 /* end of ib700wdt.c */
343