File: /usr/src/linux/drivers/char/acquirewdt.c
1 /*
2 * Acquire Single Board Computer Watchdog Timer driver for Linux 2.1.x
3 *
4 * Based on wdt.c. Original copyright messages:
5 *
6 * (c) Copyright 1996 Alan Cox <alan@redhat.com>, All Rights Reserved.
7 * http://www.redhat.com
8 *
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.
13 *
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.
17 *
18 * (c) Copyright 1995 Alan Cox <alan@redhat.com>
19 *
20 */
21
22 #include <linux/config.h>
23 #include <linux/module.h>
24 #include <linux/version.h>
25 #include <linux/types.h>
26 #include <linux/errno.h>
27 #include <linux/kernel.h>
28 #include <linux/sched.h>
29 #include <linux/miscdevice.h>
30 #include <linux/watchdog.h>
31 #include <linux/slab.h>
32 #include <linux/ioport.h>
33 #include <linux/fcntl.h>
34 #include <asm/io.h>
35 #include <asm/uaccess.h>
36 #include <asm/system.h>
37 #include <linux/notifier.h>
38 #include <linux/reboot.h>
39 #include <linux/init.h>
40 #include <linux/spinlock.h>
41 #include <linux/smp_lock.h>
42
43 static int acq_is_open;
44 static spinlock_t acq_lock;
45
46 /*
47 * You must set these - there is no sane way to probe for this board.
48 */
49
50 #define WDT_STOP 0x43
51 #define WDT_START 0x443
52
53 #define WD_TIMO (100*60) /* 1 minute */
54
55
56 /*
57 * Kernel methods.
58 */
59
60
61 static void acq_ping(void)
62 {
63 /* Write a watchdog value */
64 inb_p(WDT_START);
65 }
66
67 static ssize_t acq_write(struct file *file, const char *buf, size_t count, loff_t *ppos)
68 {
69 /* Can't seek (pwrite) on this device */
70 if (ppos != &file->f_pos)
71 return -ESPIPE;
72
73 if(count)
74 {
75 acq_ping();
76 return 1;
77 }
78 return 0;
79 }
80
81 static ssize_t acq_read(struct file *file, char *buf, size_t count, loff_t *ppos)
82 {
83 return -EINVAL;
84 }
85
86
87
88 static int acq_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
89 unsigned long arg)
90 {
91 static struct watchdog_info ident=
92 {
93 WDIOF_KEEPALIVEPING, 1, "Acquire WDT"
94 };
95
96 switch(cmd)
97 {
98 case WDIOC_GETSUPPORT:
99 if (copy_to_user((struct watchdog_info *)arg, &ident, sizeof(ident)))
100 return -EFAULT;
101 break;
102
103 case WDIOC_GETSTATUS:
104 if (copy_to_user((int *)arg, &acq_is_open, sizeof(int)))
105 return -EFAULT;
106 break;
107
108 case WDIOC_KEEPALIVE:
109 acq_ping();
110 break;
111
112 default:
113 return -ENOTTY;
114 }
115 return 0;
116 }
117
118 static int acq_open(struct inode *inode, struct file *file)
119 {
120 switch(MINOR(inode->i_rdev))
121 {
122 case WATCHDOG_MINOR:
123 spin_lock(&acq_lock);
124 if(acq_is_open)
125 {
126 spin_unlock(&acq_lock);
127 return -EBUSY;
128 }
129 /*
130 * Activate
131 */
132
133 acq_is_open=1;
134 inb_p(WDT_START);
135 spin_unlock(&acq_lock);
136 return 0;
137 default:
138 return -ENODEV;
139 }
140 }
141
142 static int acq_close(struct inode *inode, struct file *file)
143 {
144 lock_kernel();
145 if(MINOR(inode->i_rdev)==WATCHDOG_MINOR)
146 {
147 spin_lock(&acq_lock);
148 #ifndef CONFIG_WATCHDOG_NOWAYOUT
149 inb_p(WDT_STOP);
150 #endif
151 acq_is_open=0;
152 spin_unlock(&acq_lock);
153 }
154 unlock_kernel();
155 return 0;
156 }
157
158 /*
159 * Notifier for system down
160 */
161
162 static int acq_notify_sys(struct notifier_block *this, unsigned long code,
163 void *unused)
164 {
165 if(code==SYS_DOWN || code==SYS_HALT)
166 {
167 /* Turn the card off */
168 inb_p(WDT_STOP);
169 }
170 return NOTIFY_DONE;
171 }
172
173 /*
174 * Kernel Interfaces
175 */
176
177
178 static struct file_operations acq_fops = {
179 owner: THIS_MODULE,
180 read: acq_read,
181 write: acq_write,
182 ioctl: acq_ioctl,
183 open: acq_open,
184 release: acq_close,
185 };
186
187 static struct miscdevice acq_miscdev=
188 {
189 WATCHDOG_MINOR,
190 "watchdog",
191 &acq_fops
192 };
193
194
195 /*
196 * The WDT card needs to learn about soft shutdowns in order to
197 * turn the timebomb registers off.
198 */
199
200 static struct notifier_block acq_notifier=
201 {
202 acq_notify_sys,
203 NULL,
204 0
205 };
206
207 static int __init acq_init(void)
208 {
209 printk("WDT driver for Acquire single board computer initialising.\n");
210
211 spin_lock_init(&acq_lock);
212 misc_register(&acq_miscdev);
213 request_region(WDT_STOP, 1, "Acquire WDT");
214 request_region(WDT_START, 1, "Acquire WDT");
215 register_reboot_notifier(&acq_notifier);
216 return 0;
217 }
218
219 static void __exit acq_exit(void)
220 {
221 misc_deregister(&acq_miscdev);
222 unregister_reboot_notifier(&acq_notifier);
223 release_region(WDT_STOP,1);
224 release_region(WDT_START,1);
225 }
226
227 module_init(acq_init);
228 module_exit(acq_exit);
229
230 MODULE_LICENSE("GPL");
231 EXPORT_NO_SYMBOLS;
232