1 /*
2  *	Advantech Single Board Computer WDT driver
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@lxorguk.ukuu.org.uk>,
10  *						All Rights Reserved.
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@lxorguk.ukuu.org.uk>
22  *
23  *	14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
24  *	    Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
25  *
26  *	16-Oct-2002 Rob Radez <rob@osinvestor.com>
27  *	    Clean up ioctls, clean up init + exit, add expect close support,
28  *	    add wdt_start and wdt_stop as parameters.
29  */
30 
31 #include <linux/module.h>
32 #include <linux/moduleparam.h>
33 #include <linux/types.h>
34 #include <linux/miscdevice.h>
35 #include <linux/watchdog.h>
36 #include <linux/fs.h>
37 #include <linux/ioport.h>
38 #include <linux/platform_device.h>
39 #include <linux/init.h>
40 #include <linux/io.h>
41 #include <linux/uaccess.h>
42 
43 #include <asm/system.h>
44 
45 #define DRV_NAME "advantechwdt"
46 #define PFX DRV_NAME ": "
47 #define WATCHDOG_NAME "Advantech WDT"
48 #define WATCHDOG_TIMEOUT 60		/* 60 sec default timeout */
49 
50 /* the watchdog platform device */
51 static struct platform_device *advwdt_platform_device;
52 static unsigned long advwdt_is_open;
53 static char adv_expect_close;
54 
55 /*
56  *	You must set these - there is no sane way to probe for this board.
57  *
58  *	To enable or restart, write the timeout value in seconds (1 to 63)
59  *	to I/O port wdt_start.  To disable, read I/O port wdt_stop.
60  *	Both are 0x443 for most boards (tested on a PCA-6276VE-00B1), but
61  *	check your manual (at least the PCA-6159 seems to be different -
62  *	the manual says wdt_stop is 0x43, not 0x443).
63  *	(0x43 is also a write-only control register for the 8254 timer!)
64  */
65 
66 static int wdt_stop = 0x443;
67 module_param(wdt_stop, int, 0);
68 MODULE_PARM_DESC(wdt_stop, "Advantech WDT 'stop' io port (default 0x443)");
69 
70 static int wdt_start = 0x443;
71 module_param(wdt_start, int, 0);
72 MODULE_PARM_DESC(wdt_start, "Advantech WDT 'start' io port (default 0x443)");
73 
74 static int timeout = WATCHDOG_TIMEOUT;	/* in seconds */
75 module_param(timeout, int, 0);
76 MODULE_PARM_DESC(timeout,
77 	"Watchdog timeout in seconds. 1<= timeout <=63, default="
78 		__MODULE_STRING(WATCHDOG_TIMEOUT) ".");
79 
80 static int nowayout = WATCHDOG_NOWAYOUT;
81 module_param(nowayout, int, 0);
82 MODULE_PARM_DESC(nowayout,
83 	"Watchdog cannot be stopped once started (default="
84 		__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
85 
86 /*
87  *	Watchdog Operations
88  */
89 
90 static void advwdt_ping(void)
91 {
92 	/* Write a watchdog value */
93 	outb_p(timeout, wdt_start);
94 }
95 
96 static void advwdt_disable(void)
97 {
98 	inb_p(wdt_stop);
99 }
100 
101 static int advwdt_set_heartbeat(int t)
102 {
103 	if (t < 1 || t > 63)
104 		return -EINVAL;
105 	timeout = t;
106 	return 0;
107 }
108 
109 /*
110  *	/dev/watchdog handling
111  */
112 
113 static ssize_t advwdt_write(struct file *file, const char __user *buf,
114 						size_t count, loff_t *ppos)
115 {
116 	if (count) {
117 		if (!nowayout) {
118 			size_t i;
119 
120 			adv_expect_close = 0;
121 
122 			for (i = 0; i != count; i++) {
123 				char c;
124 				if (get_user(c, buf + i))
125 					return -EFAULT;
126 				if (c == 'V')
127 					adv_expect_close = 42;
128 			}
129 		}
130 		advwdt_ping();
131 	}
132 	return count;
133 }
134 
135 static long advwdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
136 {
137 	int new_timeout;
138 	void __user *argp = (void __user *)arg;
139 	int __user *p = argp;
140 	static struct watchdog_info ident = {
141 		.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
142 		.firmware_version = 1,
143 		.identity = WATCHDOG_NAME,
144 	};
145 
146 	switch (cmd) {
147 	case WDIOC_GETSUPPORT:
148 		if (copy_to_user(argp, &ident, sizeof(ident)))
149 			return -EFAULT;
150 		break;
151 
152 	case WDIOC_GETSTATUS:
153 	case WDIOC_GETBOOTSTATUS:
154 		return put_user(0, p);
155 
156 	case WDIOC_SETOPTIONS:
157 	{
158 		int options, retval = -EINVAL;
159 
160 		if (get_user(options, p))
161 			return -EFAULT;
162 		if (options & WDIOS_DISABLECARD) {
163 			advwdt_disable();
164 			retval = 0;
165 		}
166 		if (options & WDIOS_ENABLECARD) {
167 			advwdt_ping();
168 			retval = 0;
169 		}
170 		return retval;
171 	}
172 	case WDIOC_KEEPALIVE:
173 		advwdt_ping();
174 		break;
175 
176 	case WDIOC_SETTIMEOUT:
177 		if (get_user(new_timeout, p))
178 			return -EFAULT;
179 		if (advwdt_set_heartbeat(new_timeout))
180 			return -EINVAL;
181 		advwdt_ping();
182 		/* Fall */
183 	case WDIOC_GETTIMEOUT:
184 		return put_user(timeout, p);
185 	default:
186 		return -ENOTTY;
187 	}
188 	return 0;
189 }
190 
191 static int advwdt_open(struct inode *inode, struct file *file)
192 {
193 	if (test_and_set_bit(0, &advwdt_is_open))
194 		return -EBUSY;
195 	/*
196 	 *	Activate
197 	 */
198 
199 	advwdt_ping();
200 	return nonseekable_open(inode, file);
201 }
202 
203 static int advwdt_close(struct inode *inode, struct file *file)
204 {
205 	if (adv_expect_close == 42) {
206 		advwdt_disable();
207 	} else {
208 		printk(KERN_CRIT PFX
209 				"Unexpected close, not stopping watchdog!\n");
210 		advwdt_ping();
211 	}
212 	clear_bit(0, &advwdt_is_open);
213 	adv_expect_close = 0;
214 	return 0;
215 }
216 
217 /*
218  *	Kernel Interfaces
219  */
220 
221 static const struct file_operations advwdt_fops = {
222 	.owner		= THIS_MODULE,
223 	.llseek		= no_llseek,
224 	.write		= advwdt_write,
225 	.unlocked_ioctl	= advwdt_ioctl,
226 	.open		= advwdt_open,
227 	.release	= advwdt_close,
228 };
229 
230 static struct miscdevice advwdt_miscdev = {
231 	.minor	= WATCHDOG_MINOR,
232 	.name	= "watchdog",
233 	.fops	= &advwdt_fops,
234 };
235 
236 /*
237  *	Init & exit routines
238  */
239 
240 static int __devinit advwdt_probe(struct platform_device *dev)
241 {
242 	int ret;
243 
244 	if (wdt_stop != wdt_start) {
245 		if (!request_region(wdt_stop, 1, WATCHDOG_NAME)) {
246 			printk(KERN_ERR PFX
247 				"I/O address 0x%04x already in use\n",
248 								wdt_stop);
249 			ret = -EIO;
250 			goto out;
251 		}
252 	}
253 
254 	if (!request_region(wdt_start, 1, WATCHDOG_NAME)) {
255 		printk(KERN_ERR PFX
256 				"I/O address 0x%04x already in use\n",
257 								wdt_start);
258 		ret = -EIO;
259 		goto unreg_stop;
260 	}
261 
262 	/* Check that the heartbeat value is within it's range ; if not reset to the default */
263 	if (advwdt_set_heartbeat(timeout)) {
264 		advwdt_set_heartbeat(WATCHDOG_TIMEOUT);
265 		printk(KERN_INFO PFX
266 			"timeout value must be 1<=x<=63, using %d\n", timeout);
267 	}
268 
269 	ret = misc_register(&advwdt_miscdev);
270 	if (ret != 0) {
271 		printk(KERN_ERR PFX
272 			"cannot register miscdev on minor=%d (err=%d)\n",
273 							WATCHDOG_MINOR, ret);
274 		goto unreg_regions;
275 	}
276 	printk(KERN_INFO PFX "initialized. timeout=%d sec (nowayout=%d)\n",
277 		timeout, nowayout);
278 out:
279 	return ret;
280 unreg_regions:
281 	release_region(wdt_start, 1);
282 unreg_stop:
283 	if (wdt_stop != wdt_start)
284 		release_region(wdt_stop, 1);
285 	goto out;
286 }
287 
288 static int __devexit advwdt_remove(struct platform_device *dev)
289 {
290 	misc_deregister(&advwdt_miscdev);
291 	release_region(wdt_start, 1);
292 	if (wdt_stop != wdt_start)
293 		release_region(wdt_stop, 1);
294 
295 	return 0;
296 }
297 
298 static void advwdt_shutdown(struct platform_device *dev)
299 {
300 	/* Turn the WDT off if we have a soft shutdown */
301 	advwdt_disable();
302 }
303 
304 static struct platform_driver advwdt_driver = {
305 	.probe		= advwdt_probe,
306 	.remove		= __devexit_p(advwdt_remove),
307 	.shutdown	= advwdt_shutdown,
308 	.driver		= {
309 		.owner	= THIS_MODULE,
310 		.name	= DRV_NAME,
311 	},
312 };
313 
314 static int __init advwdt_init(void)
315 {
316 	int err;
317 
318 	printk(KERN_INFO
319 	     "WDT driver for Advantech single board computer initialising.\n");
320 
321 	err = platform_driver_register(&advwdt_driver);
322 	if (err)
323 		return err;
324 
325 	advwdt_platform_device = platform_device_register_simple(DRV_NAME,
326 								-1, NULL, 0);
327 	if (IS_ERR(advwdt_platform_device)) {
328 		err = PTR_ERR(advwdt_platform_device);
329 		goto unreg_platform_driver;
330 	}
331 
332 	return 0;
333 
334 unreg_platform_driver:
335 	platform_driver_unregister(&advwdt_driver);
336 	return err;
337 }
338 
339 static void __exit advwdt_exit(void)
340 {
341 	platform_device_unregister(advwdt_platform_device);
342 	platform_driver_unregister(&advwdt_driver);
343 	printk(KERN_INFO PFX "Watchdog Module Unloaded.\n");
344 }
345 
346 module_init(advwdt_init);
347 module_exit(advwdt_exit);
348 
349 MODULE_LICENSE("GPL");
350 MODULE_AUTHOR("Marek Michalkiewicz <marekm@linux.org.pl>");
351 MODULE_DESCRIPTION("Advantech Single Board Computer WDT driver");
352 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
353