8ab757d3df5fba9c8867c3901298a19b76faa465
[linux-2.6.git] / drivers / watchdog / sbc7240_wdt.c
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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
20
21 #include <linux/fs.h>
22 #include <linux/init.h>
23 #include <linux/ioport.h>
24 #include <linux/jiffies.h>
25 #include <linux/module.h>
26 #include <linux/moduleparam.h>
27 #include <linux/miscdevice.h>
28 #include <linux/notifier.h>
29 #include <linux/reboot.h>
30 #include <linux/types.h>
31 #include <linux/watchdog.h>
32 #include <linux/io.h>
33 #include <linux/uaccess.h>
34 #include <linux/atomic.h>
35 #include <asm/system.h>
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 bool nowayout = WATCHDOG_NOWAYOUT;
51 module_param(nowayout, bool, 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                 pr_info("Watchdog timer is now disabled\n");
69         }
70 }
71
72 static void wdt_enable(void)
73 {
74         /* enable the watchdog */
75         if (!test_and_set_bit(SBC7240_ENABLED_STATUS_BIT, &wdt_status)) {
76                 inb_p(SBC7240_ENABLE_PORT);
77                 pr_info("Watchdog timer is now enabled\n");
78         }
79 }
80
81 static int wdt_set_timeout(int t)
82 {
83         if (t < 1 || t > SBC7240_MAX_TIMEOUT) {
84                 pr_err("timeout value must be 1<=x<=%d\n", SBC7240_MAX_TIMEOUT);
85                 return -1;
86         }
87         /* set the timeout */
88         outb_p((unsigned)t, SBC7240_SET_TIMEOUT_PORT);
89         timeout = t;
90         pr_info("timeout set to %d seconds\n", t);
91         return 0;
92 }
93
94 /* Whack the dog */
95 static inline void wdt_keepalive(void)
96 {
97         if (test_bit(SBC7240_ENABLED_STATUS_BIT, &wdt_status))
98                 inb_p(SBC7240_ENABLE_PORT);
99 }
100
101 /*
102  * /dev/watchdog handling
103  */
104 static ssize_t fop_write(struct file *file, const char __user *buf,
105                          size_t count, loff_t *ppos)
106 {
107         size_t i;
108         char c;
109
110         if (count) {
111                 if (!nowayout) {
112                         clear_bit(SBC7240_EXPECT_CLOSE_STATUS_BIT,
113                                 &wdt_status);
114
115                         /* is there a magic char ? */
116                         for (i = 0; i != count; i++) {
117                                 if (get_user(c, buf + i))
118                                         return -EFAULT;
119                                 if (c == SBC7240_MAGIC_CHAR) {
120                                         set_bit(SBC7240_EXPECT_CLOSE_STATUS_BIT,
121                                                 &wdt_status);
122                                         break;
123                                 }
124                         }
125                 }
126
127                 wdt_keepalive();
128         }
129
130         return count;
131 }
132
133 static int fop_open(struct inode *inode, struct file *file)
134 {
135         if (test_and_set_bit(SBC7240_OPEN_STATUS_BIT, &wdt_status))
136                 return -EBUSY;
137
138         wdt_enable();
139
140         return nonseekable_open(inode, file);
141 }
142
143 static int fop_close(struct inode *inode, struct file *file)
144 {
145         if (test_and_clear_bit(SBC7240_EXPECT_CLOSE_STATUS_BIT, &wdt_status)
146             || !nowayout) {
147                 wdt_disable();
148         } else {
149                 pr_crit("Unexpected close, not stopping watchdog!\n");
150                 wdt_keepalive();
151         }
152
153         clear_bit(SBC7240_OPEN_STATUS_BIT, &wdt_status);
154         return 0;
155 }
156
157 static const struct watchdog_info ident = {
158         .options = WDIOF_KEEPALIVEPING|
159                    WDIOF_SETTIMEOUT|
160                    WDIOF_MAGICCLOSE,
161         .firmware_version = 1,
162         .identity = "SBC7240",
163 };
164
165
166 static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
167 {
168         switch (cmd) {
169         case WDIOC_GETSUPPORT:
170                 return copy_to_user((void __user *)arg, &ident, sizeof(ident))
171                                                  ? -EFAULT : 0;
172         case WDIOC_GETSTATUS:
173         case WDIOC_GETBOOTSTATUS:
174                 return put_user(0, (int __user *)arg);
175         case WDIOC_SETOPTIONS:
176         {
177                 int options;
178                 int retval = -EINVAL;
179
180                 if (get_user(options, (int __user *)arg))
181                         return -EFAULT;
182
183                 if (options & WDIOS_DISABLECARD) {
184                         wdt_disable();
185                         retval = 0;
186                 }
187
188                 if (options & WDIOS_ENABLECARD) {
189                         wdt_enable();
190                         retval = 0;
191                 }
192
193                 return retval;
194         }
195         case WDIOC_KEEPALIVE:
196                 wdt_keepalive();
197                 return 0;
198         case WDIOC_SETTIMEOUT:
199         {
200                 int new_timeout;
201
202                 if (get_user(new_timeout, (int __user *)arg))
203                         return -EFAULT;
204
205                 if (wdt_set_timeout(new_timeout))
206                         return -EINVAL;
207
208                 /* Fall through */
209         }
210         case WDIOC_GETTIMEOUT:
211                 return put_user(timeout, (int __user *)arg);
212         default:
213                 return -ENOTTY;
214         }
215 }
216
217 static const struct file_operations wdt_fops = {
218         .owner = THIS_MODULE,
219         .llseek = no_llseek,
220         .write = fop_write,
221         .open = fop_open,
222         .release = fop_close,
223         .unlocked_ioctl = fop_ioctl,
224 };
225
226 static struct miscdevice wdt_miscdev = {
227         .minor = WATCHDOG_MINOR,
228         .name = "watchdog",
229         .fops = &wdt_fops,
230 };
231
232 /*
233  *      Notifier for system down
234  */
235
236 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
237                           void *unused)
238 {
239         if (code == SYS_DOWN || code == SYS_HALT)
240                 wdt_disable();
241         return NOTIFY_DONE;
242 }
243
244 static struct notifier_block wdt_notifier = {
245         .notifier_call = wdt_notify_sys,
246 };
247
248 static void __exit sbc7240_wdt_unload(void)
249 {
250         pr_info("Removing watchdog\n");
251         misc_deregister(&wdt_miscdev);
252
253         unregister_reboot_notifier(&wdt_notifier);
254         release_region(SBC7240_ENABLE_PORT, 1);
255 }
256
257 static int __init sbc7240_wdt_init(void)
258 {
259         int rc = -EBUSY;
260
261         if (!request_region(SBC7240_ENABLE_PORT, 1, "SBC7240 WDT")) {
262                 pr_err("I/O address 0x%04x already in use\n",
263                        SBC7240_ENABLE_PORT);
264                 rc = -EIO;
265                 goto err_out;
266         }
267
268         /* The IO port 0x043 used to disable the watchdog
269          * is already claimed by the system timer, so we
270          * can't request_region() it ...*/
271
272         if (timeout < 1 || timeout > SBC7240_MAX_TIMEOUT) {
273                 timeout = SBC7240_TIMEOUT;
274                 pr_info("timeout value must be 1<=x<=%d, using %d\n",
275                         SBC7240_MAX_TIMEOUT, timeout);
276         }
277         wdt_set_timeout(timeout);
278         wdt_disable();
279
280         rc = register_reboot_notifier(&wdt_notifier);
281         if (rc) {
282                 pr_err("cannot register reboot notifier (err=%d)\n", rc);
283                 goto err_out_region;
284         }
285
286         rc = misc_register(&wdt_miscdev);
287         if (rc) {
288                 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
289                        wdt_miscdev.minor, rc);
290                 goto err_out_reboot_notifier;
291         }
292
293         pr_info("Watchdog driver for SBC7240 initialised (nowayout=%d)\n",
294                 nowayout);
295
296         return 0;
297
298 err_out_reboot_notifier:
299         unregister_reboot_notifier(&wdt_notifier);
300 err_out_region:
301         release_region(SBC7240_ENABLE_PORT, 1);
302 err_out:
303         return rc;
304 }
305
306 module_init(sbc7240_wdt_init);
307 module_exit(sbc7240_wdt_unload);
308
309 MODULE_AUTHOR("Gilles Gigan");
310 MODULE_DESCRIPTION("Watchdog device driver for single board"
311                    " computers EPIC Nano 7240 from iEi");
312 MODULE_LICENSE("GPL");
313 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
314