File: /usr/src/linux/drivers/char/advantechwdt.c
1 /*
2 * Advantech Single Board Computer WDT driver for Linux 2.4.x
3 *
4 * (c) Copyright 2000-2001 Marek Michalkiewicz <marekm@linux.org.pl>
5 *
6 * Based on acquirewdt.c which is based on wdt.c.
7 * Original copyright messages:
8 *
9 * (c) Copyright 1996 Alan Cox <alan@redhat.com>, All Rights Reserved.
10 * http://www.redhat.com
11 *
12 * This program is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU General Public License
14 * as published by the Free Software Foundation; either version
15 * 2 of the License, or (at your option) any later version.
16 *
17 * Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
18 * warranty for any of this software. This material is provided
19 * "AS-IS" and at no charge.
20 *
21 * (c) Copyright 1995 Alan Cox <alan@redhat.com>
22 *
23 */
24
25 #include <linux/config.h>
26 #include <linux/module.h>
27 #include <linux/version.h>
28 #include <linux/types.h>
29 #include <linux/errno.h>
30 #include <linux/kernel.h>
31 #include <linux/sched.h>
32 #include <linux/miscdevice.h>
33 #include <linux/watchdog.h>
34 #include <linux/slab.h>
35 #include <linux/ioport.h>
36 #include <linux/fcntl.h>
37 #include <asm/io.h>
38 #include <asm/uaccess.h>
39 #include <asm/system.h>
40 #include <linux/notifier.h>
41 #include <linux/reboot.h>
42 #include <linux/init.h>
43 #include <linux/spinlock.h>
44 #include <linux/smp_lock.h>
45
46 static int advwdt_is_open;
47 static spinlock_t advwdt_lock;
48
49 /*
50 * You must set these - there is no sane way to probe for this board.
51 *
52 * To enable or restart, write the timeout value in seconds (1 to 63)
53 * to I/O port WDT_START. To disable, read I/O port WDT_STOP.
54 * Both are 0x443 for most boards (tested on a PCA-6276VE-00B1), but
55 * check your manual (at least the PCA-6159 seems to be different -
56 * the manual says WDT_STOP is 0x43, not 0x443).
57 * (0x43 is also a write-only control register for the 8254 timer!)
58 *
59 * TODO: module parameters to set the I/O port addresses and NOWAYOUT
60 * option at load time.
61 */
62
63 #define WDT_STOP 0x443
64 #define WDT_START 0x443
65
66 #define WD_TIMO 60 /* 1 minute */
67
68 /*
69 * Kernel methods.
70 */
71
72 static void
73 advwdt_ping(void)
74 {
75 /* Write a watchdog value */
76 outb_p(WD_TIMO, WDT_START);
77 }
78
79 static ssize_t
80 advwdt_write(struct file *file, const char *buf, size_t count, loff_t *ppos)
81 {
82 /* Can't seek (pwrite) on this device */
83 if (ppos != &file->f_pos)
84 return -ESPIPE;
85
86 if (count) {
87 advwdt_ping();
88 return 1;
89 }
90 return 0;
91 }
92
93 static ssize_t
94 advwdt_read(struct file *file, char *buf, size_t count, loff_t *ppos)
95 {
96 return -EINVAL;
97 }
98
99 static int
100 advwdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
101 unsigned long arg)
102 {
103 static struct watchdog_info ident = {
104 WDIOF_KEEPALIVEPING, 1, "Advantech WDT"
105 };
106
107 switch (cmd) {
108 case WDIOC_GETSUPPORT:
109 if (copy_to_user((struct watchdog_info *)arg, &ident, sizeof(ident)))
110 return -EFAULT;
111 break;
112
113 case WDIOC_GETSTATUS:
114 if (copy_to_user((int *)arg, &advwdt_is_open, sizeof(int)))
115 return -EFAULT;
116 break;
117
118 case WDIOC_KEEPALIVE:
119 advwdt_ping();
120 break;
121
122 default:
123 return -ENOTTY;
124 }
125 return 0;
126 }
127
128 static int
129 advwdt_open(struct inode *inode, struct file *file)
130 {
131 switch (MINOR(inode->i_rdev)) {
132 case WATCHDOG_MINOR:
133 spin_lock(&advwdt_lock);
134 if (advwdt_is_open) {
135 spin_unlock(&advwdt_lock);
136 return -EBUSY;
137 }
138 /*
139 * Activate
140 */
141
142 advwdt_is_open = 1;
143 advwdt_ping();
144 spin_unlock(&advwdt_lock);
145 return 0;
146 default:
147 return -ENODEV;
148 }
149 }
150
151 static int
152 advwdt_close(struct inode *inode, struct file *file)
153 {
154 lock_kernel();
155 if (MINOR(inode->i_rdev) == WATCHDOG_MINOR) {
156 spin_lock(&advwdt_lock);
157 #ifndef CONFIG_WATCHDOG_NOWAYOUT
158 inb_p(WDT_STOP);
159 #endif
160 advwdt_is_open = 0;
161 spin_unlock(&advwdt_lock);
162 }
163 unlock_kernel();
164 return 0;
165 }
166
167 /*
168 * Notifier for system down
169 */
170
171 static int
172 advwdt_notify_sys(struct notifier_block *this, unsigned long code,
173 void *unused)
174 {
175 if (code == SYS_DOWN || code == SYS_HALT) {
176 /* Turn the WDT off */
177 inb_p(WDT_STOP);
178 }
179 return NOTIFY_DONE;
180 }
181
182 /*
183 * Kernel Interfaces
184 */
185
186 static struct file_operations advwdt_fops = {
187 owner: THIS_MODULE,
188 read: advwdt_read,
189 write: advwdt_write,
190 ioctl: advwdt_ioctl,
191 open: advwdt_open,
192 release: advwdt_close,
193 };
194
195 static struct miscdevice advwdt_miscdev = {
196 WATCHDOG_MINOR,
197 "watchdog",
198 &advwdt_fops
199 };
200
201 /*
202 * The WDT needs to learn about soft shutdowns in order to
203 * turn the timebomb registers off.
204 */
205
206 static struct notifier_block advwdt_notifier = {
207 advwdt_notify_sys,
208 NULL,
209 0
210 };
211
212 static int __init
213 advwdt_init(void)
214 {
215 printk("WDT driver for Advantech single board computer initialising.\n");
216
217 spin_lock_init(&advwdt_lock);
218 misc_register(&advwdt_miscdev);
219 #if WDT_START != WDT_STOP
220 request_region(WDT_STOP, 1, "Advantech WDT");
221 #endif
222 request_region(WDT_START, 1, "Advantech WDT");
223 register_reboot_notifier(&advwdt_notifier);
224 return 0;
225 }
226
227 static void __exit
228 advwdt_exit(void)
229 {
230 misc_deregister(&advwdt_miscdev);
231 unregister_reboot_notifier(&advwdt_notifier);
232 #if WDT_START != WDT_STOP
233 release_region(WDT_STOP,1);
234 #endif
235 release_region(WDT_START,1);
236 }
237
238 module_init(advwdt_init);
239 module_exit(advwdt_exit);
240
241 MODULE_LICENSE("GPL");
242
243 /* end of advantechwdt.c */
244
245