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 
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 
81 static void wafwdt_start(void)
82 {
83 	/* start up watchdog */
84 	outb_p(timeout, wdt_start);
85 	inb_p(wdt_start);
86 }
87 
88 static void wafwdt_stop(void)
89 {
90 	/* stop watchdog */
91 	inb_p(wdt_stop);
92 }
93 
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 
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 		/* Fall through */
178 	case WDIOC_GETTIMEOUT:
179 		return put_user(timeout, p);
180 
181 	default:
182 		return -ENOTTY;
183 	}
184 	return 0;
185 }
186 
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 
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 
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 
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 
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