1 /*
2  *	NANO7240 SBC Watchdog device driver
3  *
4  *	Based on w83877f.c by Scott Jennings,
5  *
6  *	This program is free software; you can redistribute it and/or modify
7  *	it under the terms of the GNU General Public License version 2 as
8  *	published by the Free Software Foundation;
9  *
10  *	Software distributed under the License is distributed on an "AS IS"
11  *	basis, WITHOUT WARRANTY OF ANY KIND, either express or
12  *	implied. See the License for the specific language governing
13  *	rights and limitations under the License.
14  *
15  *	(c) Copyright 2007  Gilles GIGAN <gilles.gigan@jcu.edu.au>
16  *
17  */
18 
19 #include <linux/fs.h>
20 #include <linux/init.h>
21 #include <linux/ioport.h>
22 #include <linux/jiffies.h>
23 #include <linux/module.h>
24 #include <linux/moduleparam.h>
25 #include <linux/miscdevice.h>
26 #include <linux/notifier.h>
27 #include <linux/reboot.h>
28 #include <linux/types.h>
29 #include <linux/watchdog.h>
30 #include <asm/atomic.h>
31 #include <asm/io.h>
32 #include <asm/system.h>
33 #include <asm/uaccess.h>
34 
35 #define SBC7240_PREFIX "sbc7240_wdt: "
36 
37 #define SBC7240_ENABLE_PORT		0x443
38 #define SBC7240_DISABLE_PORT		0x043
39 #define SBC7240_SET_TIMEOUT_PORT	SBC7240_ENABLE_PORT
40 #define SBC7240_MAGIC_CHAR		'V'
41 
42 #define SBC7240_TIMEOUT		30
43 #define SBC7240_MAX_TIMEOUT		255
44 static int timeout = SBC7240_TIMEOUT;	/* in seconds */
45 module_param(timeout, int, 0);
46 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (1<=timeout<="
47 		 __MODULE_STRING(SBC7240_MAX_TIMEOUT) ", default="
48 		 __MODULE_STRING(SBC7240_TIMEOUT) ")");
49 
50 static int nowayout = WATCHDOG_NOWAYOUT;
51 module_param(nowayout, int, 0);
52 MODULE_PARM_DESC(nowayout, "Disable watchdog when closing device file");
53 
54 #define SBC7240_OPEN_STATUS_BIT		0
55 #define SBC7240_ENABLED_STATUS_BIT	1
56 #define SBC7240_EXPECT_CLOSE_STATUS_BIT	2
57 static unsigned long wdt_status;
58 
59 /*
60  * Utility routines
61  */
62 
63 static void wdt_disable(void)
64 {
65 	/* disable the watchdog */
66 	if (test_and_clear_bit(SBC7240_ENABLED_STATUS_BIT, &wdt_status)) {
67 		inb_p(SBC7240_DISABLE_PORT);
68 		printk(KERN_INFO SBC7240_PREFIX
69 		       "Watchdog timer is now disabled.\n");
70 	}
71 }
72 
73 static void wdt_enable(void)
74 {
75 	/* enable the watchdog */
76 	if (!test_and_set_bit(SBC7240_ENABLED_STATUS_BIT, &wdt_status)) {
77 		inb_p(SBC7240_ENABLE_PORT);
78 		printk(KERN_INFO SBC7240_PREFIX
79 		       "Watchdog timer is now enabled.\n");
80 	}
81 }
82 
83 static int wdt_set_timeout(int t)
84 {
85 	if (t < 1 || t > SBC7240_MAX_TIMEOUT) {
86 		printk(KERN_ERR SBC7240_PREFIX
87 		       "timeout value must be 1<=x<=%d\n",
88 		       SBC7240_MAX_TIMEOUT);
89 		return -1;
90 	}
91 	/* set the timeout */
92 	outb_p((unsigned)t, SBC7240_SET_TIMEOUT_PORT);
93 	timeout = t;
94 	printk(KERN_INFO SBC7240_PREFIX "timeout set to %d seconds\n", t);
95 	return 0;
96 }
97 
98 /* Whack the dog */
99 static inline void wdt_keepalive(void)
100 {
101 	if (test_bit(SBC7240_ENABLED_STATUS_BIT, &wdt_status))
102 		inb_p(SBC7240_ENABLE_PORT);
103 }
104 
105 /*
106  * /dev/watchdog handling
107  */
108 static ssize_t fop_write(struct file *file, const char __user *buf,
109 			 size_t count, loff_t *ppos)
110 {
111 	size_t i;
112 	char c;
113 
114 	if (count) {
115 		if (!nowayout) {
116 			clear_bit(SBC7240_EXPECT_CLOSE_STATUS_BIT,
117 				&wdt_status);
118 
119 			/* is there a magic char ? */
120 			for (i = 0; i != count; i++) {
121 				if (get_user(c, buf + i))
122 					return -EFAULT;
123 				if (c == SBC7240_MAGIC_CHAR) {
124 					set_bit(SBC7240_EXPECT_CLOSE_STATUS_BIT,
125 						&wdt_status);
126 					break;
127 				}
128 			}
129 		}
130 
131 		wdt_keepalive();
132 	}
133 
134 	return count;
135 }
136 
137 static int fop_open(struct inode *inode, struct file *file)
138 {
139 	if (test_and_set_bit(SBC7240_OPEN_STATUS_BIT, &wdt_status))
140 		return -EBUSY;
141 
142 	wdt_enable();
143 
144 	return nonseekable_open(inode, file);
145 }
146 
147 static int fop_close(struct inode *inode, struct file *file)
148 {
149 	if (test_and_clear_bit(SBC7240_EXPECT_CLOSE_STATUS_BIT, &wdt_status)
150 	    || !nowayout) {
151 		wdt_disable();
152 	} else {
153 		printk(KERN_CRIT SBC7240_PREFIX
154 		       "Unexpected close, not stopping watchdog!\n");
155 		wdt_keepalive();
156 	}
157 
158 	clear_bit(SBC7240_OPEN_STATUS_BIT, &wdt_status);
159 	return 0;
160 }
161 
162 static struct watchdog_info ident = {
163 	.options = WDIOF_KEEPALIVEPING|
164 		   WDIOF_SETTIMEOUT|
165 		   WDIOF_MAGICCLOSE,
166 	.firmware_version = 1,
167 	.identity = "SBC7240",
168 };
169 
170 
171 static int fop_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
172 		     unsigned long arg)
173 {
174 	switch (cmd) {
175 	case WDIOC_GETSUPPORT:
176 		return copy_to_user
177 			((void __user *)arg, &ident, sizeof(ident))
178 			 ? -EFAULT : 0;
179 	case WDIOC_GETSTATUS:
180 	case WDIOC_GETBOOTSTATUS:
181 		return put_user(0, (int __user *)arg);
182 	case WDIOC_KEEPALIVE:
183 		wdt_keepalive();
184 		return 0;
185 	case WDIOC_SETOPTIONS:{
186 			int options;
187 			int retval = -EINVAL;
188 
189 			if (get_user(options, (int __user *)arg))
190 				return -EFAULT;
191 
192 			if (options & WDIOS_DISABLECARD) {
193 				wdt_disable();
194 				retval = 0;
195 			}
196 
197 			if (options & WDIOS_ENABLECARD) {
198 				wdt_enable();
199 				retval = 0;
200 			}
201 
202 			return retval;
203 		}
204 	case WDIOC_SETTIMEOUT:{
205 			int new_timeout;
206 
207 			if (get_user(new_timeout, (int __user *)arg))
208 				return -EFAULT;
209 
210 			if (wdt_set_timeout(new_timeout))
211 				return -EINVAL;
212 
213 			/* Fall through */
214 		}
215 	case WDIOC_GETTIMEOUT:
216 		return put_user(timeout, (int __user *)arg);
217 	default:
218 		return -ENOTTY;
219 	}
220 }
221 
222 static const struct file_operations wdt_fops = {
223 	.owner = THIS_MODULE,
224 	.llseek = no_llseek,
225 	.write = fop_write,
226 	.open = fop_open,
227 	.release = fop_close,
228 	.ioctl = fop_ioctl,
229 };
230 
231 static struct miscdevice wdt_miscdev = {
232 	.minor = WATCHDOG_MINOR,
233 	.name = "watchdog",
234 	.fops = &wdt_fops,
235 };
236 
237 /*
238  *	Notifier for system down
239  */
240 
241 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
242 			  void *unused)
243 {
244 	if (code == SYS_DOWN || code == SYS_HALT)
245 		wdt_disable();
246 	return NOTIFY_DONE;
247 }
248 
249 static struct notifier_block wdt_notifier = {
250 	.notifier_call = wdt_notify_sys,
251 };
252 
253 static void __exit sbc7240_wdt_unload(void)
254 {
255 	printk(KERN_INFO SBC7240_PREFIX "Removing watchdog\n");
256 	misc_deregister(&wdt_miscdev);
257 
258 	unregister_reboot_notifier(&wdt_notifier);
259 	release_region(SBC7240_ENABLE_PORT, 1);
260 }
261 
262 static int __init sbc7240_wdt_init(void)
263 {
264 	int rc = -EBUSY;
265 
266 	if (!request_region(SBC7240_ENABLE_PORT, 1, "SBC7240 WDT")) {
267 		printk(KERN_ERR SBC7240_PREFIX
268 		       "I/O address 0x%04x already in use\n",
269 		       SBC7240_ENABLE_PORT);
270 		rc = -EIO;
271 		goto err_out;
272 	}
273 
274 	/* The IO port 0x043 used to disable the watchdog
275 	 * is already claimed by the system timer, so we
276 	 * cant request_region() it ...*/
277 
278 	if (timeout < 1 || timeout > SBC7240_MAX_TIMEOUT) {
279 		timeout = SBC7240_TIMEOUT;
280 		printk(KERN_INFO SBC7240_PREFIX
281 		       "timeout value must be 1<=x<=%d, using %d\n",
282 		       SBC7240_MAX_TIMEOUT, timeout);
283 	}
284 	wdt_set_timeout(timeout);
285 	wdt_disable();
286 
287 	rc = register_reboot_notifier(&wdt_notifier);
288 	if (rc) {
289 		printk(KERN_ERR SBC7240_PREFIX
290 		       "cannot register reboot notifier (err=%d)\n", rc);
291 		goto err_out_region;
292 	}
293 
294 	rc = misc_register(&wdt_miscdev);
295 	if (rc) {
296 		printk(KERN_ERR SBC7240_PREFIX
297 		       "cannot register miscdev on minor=%d (err=%d)\n",
298 		       wdt_miscdev.minor, rc);
299 		goto err_out_reboot_notifier;
300 	}
301 
302 	printk(KERN_INFO SBC7240_PREFIX
303 	       "Watchdog driver for SBC7240 initialised (nowayout=%d)\n",
304 	       nowayout);
305 
306 	return 0;
307 
308 err_out_reboot_notifier:
309 	unregister_reboot_notifier(&wdt_notifier);
310 err_out_region:
311 	release_region(SBC7240_ENABLE_PORT, 1);
312 err_out:
313 	return rc;
314 }
315 
316 module_init(sbc7240_wdt_init);
317 module_exit(sbc7240_wdt_unload);
318 
319 MODULE_AUTHOR("Gilles Gigan");
320 MODULE_DESCRIPTION("Watchdog device driver for single board"
321 		   " computers EPIC Nano 7240 from iEi");
322 MODULE_LICENSE("GPL");
323 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
324 
325