1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * ICP Wafer 5823 Single Board Computer WDT driver
4 * http://www.icpamerica.com/wafer_5823.php
5 * May also work on other similar models
6 *
7 * (c) Copyright 2002 Justin Cormack <justin@street-vision.com>
8 *
9 * Release 0.02
10 *
11 * Based on advantechwdt.c which is based on wdt.c.
12 * Original copyright messages:
13 *
14 * (c) Copyright 1996-1997 Alan Cox <alan@lxorguk.ukuu.org.uk>,
15 * All Rights Reserved.
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@lxorguk.ukuu.org.uk>
22 *
23 */
24
25 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
26
27 #include <linux/module.h>
28 #include <linux/moduleparam.h>
29 #include <linux/miscdevice.h>
30 #include <linux/watchdog.h>
31 #include <linux/fs.h>
32 #include <linux/ioport.h>
33 #include <linux/notifier.h>
34 #include <linux/reboot.h>
35 #include <linux/init.h>
36 #include <linux/spinlock.h>
37 #include <linux/io.h>
38 #include <linux/uaccess.h>
39
40 #define WATCHDOG_NAME "Wafer 5823 WDT"
41 #define PFX WATCHDOG_NAME ": "
42 #define WD_TIMO 60 /* 60 sec default timeout */
43
44 static unsigned long wafwdt_is_open;
45 static char expect_close;
46 static DEFINE_SPINLOCK(wafwdt_lock);
47
48 /*
49 * You must set these - there is no sane way to probe for this board.
50 *
51 * To enable, write the timeout value in seconds (1 to 255) to I/O
52 * port WDT_START, then read the port to start the watchdog. To pat
53 * the dog, read port WDT_STOP to stop the timer, then read WDT_START
54 * to restart it again.
55 */
56
57 static int wdt_stop = 0x843;
58 static int wdt_start = 0x443;
59
60 static int timeout = WD_TIMO; /* in seconds */
61 module_param(timeout, int, 0);
62 MODULE_PARM_DESC(timeout,
63 "Watchdog timeout in seconds. 1 <= timeout <= 255, default="
64 __MODULE_STRING(WD_TIMO) ".");
65
66 static bool nowayout = WATCHDOG_NOWAYOUT;
67 module_param(nowayout, bool, 0);
68 MODULE_PARM_DESC(nowayout,
69 "Watchdog cannot be stopped once started (default="
70 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
71
wafwdt_ping(void)72 static void wafwdt_ping(void)
73 {
74 /* pat watchdog */
75 spin_lock(&wafwdt_lock);
76 inb_p(wdt_stop);
77 inb_p(wdt_start);
78 spin_unlock(&wafwdt_lock);
79 }
80
wafwdt_start(void)81 static void wafwdt_start(void)
82 {
83 /* start up watchdog */
84 outb_p(timeout, wdt_start);
85 inb_p(wdt_start);
86 }
87
wafwdt_stop(void)88 static void wafwdt_stop(void)
89 {
90 /* stop watchdog */
91 inb_p(wdt_stop);
92 }
93
wafwdt_write(struct file * file,const char __user * buf,size_t count,loff_t * ppos)94 static ssize_t wafwdt_write(struct file *file, const char __user *buf,
95 size_t count, loff_t *ppos)
96 {
97 /* See if we got the magic character 'V' and reload the timer */
98 if (count) {
99 if (!nowayout) {
100 size_t i;
101
102 /* In case it was set long ago */
103 expect_close = 0;
104
105 /* scan to see whether or not we got the magic
106 character */
107 for (i = 0; i != count; i++) {
108 char c;
109 if (get_user(c, buf + i))
110 return -EFAULT;
111 if (c == 'V')
112 expect_close = 42;
113 }
114 }
115 /* Well, anyhow someone wrote to us, we should
116 return that favour */
117 wafwdt_ping();
118 }
119 return count;
120 }
121
wafwdt_ioctl(struct file * file,unsigned int cmd,unsigned long arg)122 static long wafwdt_ioctl(struct file *file, unsigned int cmd,
123 unsigned long arg)
124 {
125 int new_timeout;
126 void __user *argp = (void __user *)arg;
127 int __user *p = argp;
128 static const struct watchdog_info ident = {
129 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
130 WDIOF_MAGICCLOSE,
131 .firmware_version = 1,
132 .identity = "Wafer 5823 WDT",
133 };
134
135 switch (cmd) {
136 case WDIOC_GETSUPPORT:
137 if (copy_to_user(argp, &ident, sizeof(ident)))
138 return -EFAULT;
139 break;
140
141 case WDIOC_GETSTATUS:
142 case WDIOC_GETBOOTSTATUS:
143 return put_user(0, p);
144
145 case WDIOC_SETOPTIONS:
146 {
147 int options, retval = -EINVAL;
148
149 if (get_user(options, p))
150 return -EFAULT;
151
152 if (options & WDIOS_DISABLECARD) {
153 wafwdt_stop();
154 retval = 0;
155 }
156
157 if (options & WDIOS_ENABLECARD) {
158 wafwdt_start();
159 retval = 0;
160 }
161
162 return retval;
163 }
164
165 case WDIOC_KEEPALIVE:
166 wafwdt_ping();
167 break;
168
169 case WDIOC_SETTIMEOUT:
170 if (get_user(new_timeout, p))
171 return -EFAULT;
172 if ((new_timeout < 1) || (new_timeout > 255))
173 return -EINVAL;
174 timeout = new_timeout;
175 wafwdt_stop();
176 wafwdt_start();
177 fallthrough;
178 case WDIOC_GETTIMEOUT:
179 return put_user(timeout, p);
180
181 default:
182 return -ENOTTY;
183 }
184 return 0;
185 }
186
wafwdt_open(struct inode * inode,struct file * file)187 static int wafwdt_open(struct inode *inode, struct file *file)
188 {
189 if (test_and_set_bit(0, &wafwdt_is_open))
190 return -EBUSY;
191
192 /*
193 * Activate
194 */
195 wafwdt_start();
196 return stream_open(inode, file);
197 }
198
wafwdt_close(struct inode * inode,struct file * file)199 static int wafwdt_close(struct inode *inode, struct file *file)
200 {
201 if (expect_close == 42)
202 wafwdt_stop();
203 else {
204 pr_crit("WDT device closed unexpectedly. WDT will not stop!\n");
205 wafwdt_ping();
206 }
207 clear_bit(0, &wafwdt_is_open);
208 expect_close = 0;
209 return 0;
210 }
211
212 /*
213 * Notifier for system down
214 */
215
wafwdt_notify_sys(struct notifier_block * this,unsigned long code,void * unused)216 static int wafwdt_notify_sys(struct notifier_block *this, unsigned long code,
217 void *unused)
218 {
219 if (code == SYS_DOWN || code == SYS_HALT)
220 wafwdt_stop();
221 return NOTIFY_DONE;
222 }
223
224 /*
225 * Kernel Interfaces
226 */
227
228 static const struct file_operations wafwdt_fops = {
229 .owner = THIS_MODULE,
230 .llseek = no_llseek,
231 .write = wafwdt_write,
232 .unlocked_ioctl = wafwdt_ioctl,
233 .compat_ioctl = compat_ptr_ioctl,
234 .open = wafwdt_open,
235 .release = wafwdt_close,
236 };
237
238 static struct miscdevice wafwdt_miscdev = {
239 .minor = WATCHDOG_MINOR,
240 .name = "watchdog",
241 .fops = &wafwdt_fops,
242 };
243
244 /*
245 * The WDT needs to learn about soft shutdowns in order to
246 * turn the timebomb registers off.
247 */
248
249 static struct notifier_block wafwdt_notifier = {
250 .notifier_call = wafwdt_notify_sys,
251 };
252
wafwdt_init(void)253 static int __init wafwdt_init(void)
254 {
255 int ret;
256
257 pr_info("WDT driver for Wafer 5823 single board computer initialising\n");
258
259 if (timeout < 1 || timeout > 255) {
260 timeout = WD_TIMO;
261 pr_info("timeout value must be 1 <= x <= 255, using %d\n",
262 timeout);
263 }
264
265 if (wdt_stop != wdt_start) {
266 if (!request_region(wdt_stop, 1, "Wafer 5823 WDT")) {
267 pr_err("I/O address 0x%04x already in use\n", wdt_stop);
268 ret = -EIO;
269 goto error;
270 }
271 }
272
273 if (!request_region(wdt_start, 1, "Wafer 5823 WDT")) {
274 pr_err("I/O address 0x%04x already in use\n", wdt_start);
275 ret = -EIO;
276 goto error2;
277 }
278
279 ret = register_reboot_notifier(&wafwdt_notifier);
280 if (ret != 0) {
281 pr_err("cannot register reboot notifier (err=%d)\n", ret);
282 goto error3;
283 }
284
285 ret = misc_register(&wafwdt_miscdev);
286 if (ret != 0) {
287 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
288 WATCHDOG_MINOR, ret);
289 goto error4;
290 }
291
292 pr_info("initialized. timeout=%d sec (nowayout=%d)\n",
293 timeout, nowayout);
294
295 return ret;
296 error4:
297 unregister_reboot_notifier(&wafwdt_notifier);
298 error3:
299 release_region(wdt_start, 1);
300 error2:
301 if (wdt_stop != wdt_start)
302 release_region(wdt_stop, 1);
303 error:
304 return ret;
305 }
306
wafwdt_exit(void)307 static void __exit wafwdt_exit(void)
308 {
309 misc_deregister(&wafwdt_miscdev);
310 unregister_reboot_notifier(&wafwdt_notifier);
311 if (wdt_stop != wdt_start)
312 release_region(wdt_stop, 1);
313 release_region(wdt_start, 1);
314 }
315
316 module_init(wafwdt_init);
317 module_exit(wafwdt_exit);
318
319 MODULE_AUTHOR("Justin Cormack");
320 MODULE_DESCRIPTION("ICP Wafer 5823 Single Board Computer WDT driver");
321 MODULE_LICENSE("GPL");
322
323 /* end of wafer5823wdt.c */
324