1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  *	Advantech Single Board Computer WDT driver
4  *
5  *	(c) Copyright 2000-2001 Marek Michalkiewicz <marekm@linux.org.pl>
6  *
7  *	Based on acquirewdt.c which is based on wdt.c.
8  *	Original copyright messages:
9  *
10  *	(c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
11  *						All Rights Reserved.
12  *
13  *	Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
14  *	warranty for any of this software. This material is provided
15  *	"AS-IS" and at no charge.
16  *
17  *	(c) Copyright 1995    Alan Cox <alan@lxorguk.ukuu.org.uk>
18  *
19  *	14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
20  *	    Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
21  *
22  *	16-Oct-2002 Rob Radez <rob@osinvestor.com>
23  *	    Clean up ioctls, clean up init + exit, add expect close support,
24  *	    add wdt_start and wdt_stop as parameters.
25  */
26 
27 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
28 
29 #include <linux/module.h>
30 #include <linux/moduleparam.h>
31 #include <linux/types.h>
32 #include <linux/miscdevice.h>
33 #include <linux/watchdog.h>
34 #include <linux/fs.h>
35 #include <linux/ioport.h>
36 #include <linux/platform_device.h>
37 #include <linux/init.h>
38 #include <linux/io.h>
39 #include <linux/uaccess.h>
40 
41 
42 #define DRV_NAME "advantechwdt"
43 #define WATCHDOG_NAME "Advantech WDT"
44 #define WATCHDOG_TIMEOUT 60		/* 60 sec default timeout */
45 
46 /* the watchdog platform device */
47 static struct platform_device *advwdt_platform_device;
48 static unsigned long advwdt_is_open;
49 static char adv_expect_close;
50 
51 /*
52  *	You must set these - there is no sane way to probe for this board.
53  *
54  *	To enable or restart, write the timeout value in seconds (1 to 63)
55  *	to I/O port wdt_start.  To disable, read I/O port wdt_stop.
56  *	Both are 0x443 for most boards (tested on a PCA-6276VE-00B1), but
57  *	check your manual (at least the PCA-6159 seems to be different -
58  *	the manual says wdt_stop is 0x43, not 0x443).
59  *	(0x43 is also a write-only control register for the 8254 timer!)
60  */
61 
62 static int wdt_stop = 0x443;
63 module_param(wdt_stop, int, 0);
64 MODULE_PARM_DESC(wdt_stop, "Advantech WDT 'stop' io port (default 0x443)");
65 
66 static int wdt_start = 0x443;
67 module_param(wdt_start, int, 0);
68 MODULE_PARM_DESC(wdt_start, "Advantech WDT 'start' io port (default 0x443)");
69 
70 static int timeout = WATCHDOG_TIMEOUT;	/* in seconds */
71 module_param(timeout, int, 0);
72 MODULE_PARM_DESC(timeout,
73 	"Watchdog timeout in seconds. 1<= timeout <=63, default="
74 		__MODULE_STRING(WATCHDOG_TIMEOUT) ".");
75 
76 static bool nowayout = WATCHDOG_NOWAYOUT;
77 module_param(nowayout, bool, 0);
78 MODULE_PARM_DESC(nowayout,
79 	"Watchdog cannot be stopped once started (default="
80 		__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
81 
82 /*
83  *	Watchdog Operations
84  */
85 
86 static void advwdt_ping(void)
87 {
88 	/* Write a watchdog value */
89 	outb_p(timeout, wdt_start);
90 }
91 
92 static void advwdt_disable(void)
93 {
94 	inb_p(wdt_stop);
95 }
96 
97 static int advwdt_set_heartbeat(int t)
98 {
99 	if (t < 1 || t > 63)
100 		return -EINVAL;
101 	timeout = t;
102 	return 0;
103 }
104 
105 /*
106  *	/dev/watchdog handling
107  */
108 
109 static ssize_t advwdt_write(struct file *file, const char __user *buf,
110 						size_t count, loff_t *ppos)
111 {
112 	if (count) {
113 		if (!nowayout) {
114 			size_t i;
115 
116 			adv_expect_close = 0;
117 
118 			for (i = 0; i != count; i++) {
119 				char c;
120 				if (get_user(c, buf + i))
121 					return -EFAULT;
122 				if (c == 'V')
123 					adv_expect_close = 42;
124 			}
125 		}
126 		advwdt_ping();
127 	}
128 	return count;
129 }
130 
131 static long advwdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
132 {
133 	int new_timeout;
134 	void __user *argp = (void __user *)arg;
135 	int __user *p = argp;
136 	static const struct watchdog_info ident = {
137 		.options = WDIOF_KEEPALIVEPING |
138 			   WDIOF_SETTIMEOUT |
139 			   WDIOF_MAGICCLOSE,
140 		.firmware_version = 1,
141 		.identity = WATCHDOG_NAME,
142 	};
143 
144 	switch (cmd) {
145 	case WDIOC_GETSUPPORT:
146 		if (copy_to_user(argp, &ident, sizeof(ident)))
147 			return -EFAULT;
148 		break;
149 
150 	case WDIOC_GETSTATUS:
151 	case WDIOC_GETBOOTSTATUS:
152 		return put_user(0, p);
153 
154 	case WDIOC_SETOPTIONS:
155 	{
156 		int options, retval = -EINVAL;
157 
158 		if (get_user(options, p))
159 			return -EFAULT;
160 		if (options & WDIOS_DISABLECARD) {
161 			advwdt_disable();
162 			retval = 0;
163 		}
164 		if (options & WDIOS_ENABLECARD) {
165 			advwdt_ping();
166 			retval = 0;
167 		}
168 		return retval;
169 	}
170 	case WDIOC_KEEPALIVE:
171 		advwdt_ping();
172 		break;
173 
174 	case WDIOC_SETTIMEOUT:
175 		if (get_user(new_timeout, p))
176 			return -EFAULT;
177 		if (advwdt_set_heartbeat(new_timeout))
178 			return -EINVAL;
179 		advwdt_ping();
180 		fallthrough;
181 	case WDIOC_GETTIMEOUT:
182 		return put_user(timeout, p);
183 	default:
184 		return -ENOTTY;
185 	}
186 	return 0;
187 }
188 
189 static int advwdt_open(struct inode *inode, struct file *file)
190 {
191 	if (test_and_set_bit(0, &advwdt_is_open))
192 		return -EBUSY;
193 	/*
194 	 *	Activate
195 	 */
196 
197 	advwdt_ping();
198 	return stream_open(inode, file);
199 }
200 
201 static int advwdt_close(struct inode *inode, struct file *file)
202 {
203 	if (adv_expect_close == 42) {
204 		advwdt_disable();
205 	} else {
206 		pr_crit("Unexpected close, not stopping watchdog!\n");
207 		advwdt_ping();
208 	}
209 	clear_bit(0, &advwdt_is_open);
210 	adv_expect_close = 0;
211 	return 0;
212 }
213 
214 /*
215  *	Kernel Interfaces
216  */
217 
218 static const struct file_operations advwdt_fops = {
219 	.owner		= THIS_MODULE,
220 	.llseek		= no_llseek,
221 	.write		= advwdt_write,
222 	.unlocked_ioctl	= advwdt_ioctl,
223 	.compat_ioctl	= compat_ptr_ioctl,
224 	.open		= advwdt_open,
225 	.release	= advwdt_close,
226 };
227 
228 static struct miscdevice advwdt_miscdev = {
229 	.minor	= WATCHDOG_MINOR,
230 	.name	= "watchdog",
231 	.fops	= &advwdt_fops,
232 };
233 
234 /*
235  *	Init & exit routines
236  */
237 
238 static int __init advwdt_probe(struct platform_device *dev)
239 {
240 	int ret;
241 
242 	if (wdt_stop != wdt_start) {
243 		if (!request_region(wdt_stop, 1, WATCHDOG_NAME)) {
244 			pr_err("I/O address 0x%04x already in use\n",
245 			       wdt_stop);
246 			ret = -EIO;
247 			goto out;
248 		}
249 	}
250 
251 	if (!request_region(wdt_start, 1, WATCHDOG_NAME)) {
252 		pr_err("I/O address 0x%04x already in use\n", wdt_start);
253 		ret = -EIO;
254 		goto unreg_stop;
255 	}
256 
257 	/* Check that the heartbeat value is within it's range ;
258 	 * if not reset to the default */
259 	if (advwdt_set_heartbeat(timeout)) {
260 		advwdt_set_heartbeat(WATCHDOG_TIMEOUT);
261 		pr_info("timeout value must be 1<=x<=63, using %d\n", timeout);
262 	}
263 
264 	ret = misc_register(&advwdt_miscdev);
265 	if (ret != 0) {
266 		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
267 		       WATCHDOG_MINOR, ret);
268 		goto unreg_regions;
269 	}
270 	pr_info("initialized. timeout=%d sec (nowayout=%d)\n",
271 		timeout, nowayout);
272 out:
273 	return ret;
274 unreg_regions:
275 	release_region(wdt_start, 1);
276 unreg_stop:
277 	if (wdt_stop != wdt_start)
278 		release_region(wdt_stop, 1);
279 	goto out;
280 }
281 
282 static int advwdt_remove(struct platform_device *dev)
283 {
284 	misc_deregister(&advwdt_miscdev);
285 	release_region(wdt_start, 1);
286 	if (wdt_stop != wdt_start)
287 		release_region(wdt_stop, 1);
288 
289 	return 0;
290 }
291 
292 static void advwdt_shutdown(struct platform_device *dev)
293 {
294 	/* Turn the WDT off if we have a soft shutdown */
295 	advwdt_disable();
296 }
297 
298 static struct platform_driver advwdt_driver = {
299 	.remove		= advwdt_remove,
300 	.shutdown	= advwdt_shutdown,
301 	.driver		= {
302 		.name	= DRV_NAME,
303 	},
304 };
305 
306 static int __init advwdt_init(void)
307 {
308 	int err;
309 
310 	pr_info("WDT driver for Advantech single board computer initialising\n");
311 
312 	advwdt_platform_device = platform_device_register_simple(DRV_NAME,
313 								-1, NULL, 0);
314 	if (IS_ERR(advwdt_platform_device))
315 		return PTR_ERR(advwdt_platform_device);
316 
317 	err = platform_driver_probe(&advwdt_driver, advwdt_probe);
318 	if (err)
319 		goto unreg_platform_device;
320 
321 	return 0;
322 
323 unreg_platform_device:
324 	platform_device_unregister(advwdt_platform_device);
325 	return err;
326 }
327 
328 static void __exit advwdt_exit(void)
329 {
330 	platform_device_unregister(advwdt_platform_device);
331 	platform_driver_unregister(&advwdt_driver);
332 	pr_info("Watchdog Module Unloaded\n");
333 }
334 
335 module_init(advwdt_init);
336 module_exit(advwdt_exit);
337 
338 MODULE_LICENSE("GPL");
339 MODULE_AUTHOR("Marek Michalkiewicz <marekm@linux.org.pl>");
340 MODULE_DESCRIPTION("Advantech Single Board Computer WDT driver");
341