watchdog: nowayout is bool
[linux-2.6.git] / drivers / watchdog / ib700wdt.c
1 /*
2  *      IB700 Single Board Computer WDT driver
3  *
4  *      (c) Copyright 2001 Charles Howes <chowes@vsol.net>
5  *
6  *      Based on advantechwdt.c which is based on acquirewdt.c which
7  *      is based on wdt.c.
8  *
9  *      (c) Copyright 2000-2001 Marek Michalkiewicz <marekm@linux.org.pl>
10  *
11  *      Based on acquirewdt.c which is based on wdt.c.
12  *      Original copyright messages:
13  *
14  *      (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
15  *                                              All Rights Reserved.
16  *
17  *      This program is free software; you can redistribute it and/or
18  *      modify it under the terms of the GNU General Public License
19  *      as published by the Free Software Foundation; either version
20  *      2 of the License, or (at your option) any later version.
21  *
22  *      Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
23  *      warranty for any of this software. This material is provided
24  *      "AS-IS" and at no charge.
25  *
26  *      (c) Copyright 1995    Alan Cox <alan@lxorguk.ukuu.org.uk>
27  *
28  *      14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
29  *           Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
30  *           Added timeout module option to override default
31  *
32  */
33
34 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
35
36 #include <linux/module.h>
37 #include <linux/types.h>
38 #include <linux/miscdevice.h>
39 #include <linux/watchdog.h>
40 #include <linux/ioport.h>
41 #include <linux/fs.h>
42 #include <linux/init.h>
43 #include <linux/spinlock.h>
44 #include <linux/moduleparam.h>
45 #include <linux/platform_device.h>
46 #include <linux/io.h>
47 #include <linux/uaccess.h>
48
49 #include <asm/system.h>
50
51 static struct platform_device *ibwdt_platform_device;
52 static unsigned long ibwdt_is_open;
53 static DEFINE_SPINLOCK(ibwdt_lock);
54 static char expect_close;
55
56 /* Module information */
57 #define DRV_NAME "ib700wdt"
58
59 /*
60  *
61  * Watchdog Timer Configuration
62  *
63  * The function of the watchdog timer is to reset the system
64  * automatically and is defined at I/O port 0443H.  To enable the
65  * watchdog timer and allow the system to reset, write I/O port 0443H.
66  * To disable the timer, write I/O port 0441H for the system to stop the
67  * watchdog function.  The timer has a tolerance of 20% for its
68  * intervals.
69  *
70  * The following describes how the timer should be programmed.
71  *
72  * Enabling Watchdog:
73  * MOV AX,000FH (Choose the values from 0 to F)
74  * MOV DX,0443H
75  * OUT DX,AX
76  *
77  * Disabling Watchdog:
78  * MOV AX,000FH (Any value is fine.)
79  * MOV DX,0441H
80  * OUT DX,AX
81  *
82  * Watchdog timer control table:
83  * Level   Value  Time/sec | Level Value Time/sec
84  *   1       F       0     |   9     7      16
85  *   2       E       2     |   10    6      18
86  *   3       D       4     |   11    5      20
87  *   4       C       6     |   12    4      22
88  *   5       B       8     |   13    3      24
89  *   6       A       10    |   14    2      26
90  *   7       9       12    |   15    1      28
91  *   8       8       14    |   16    0      30
92  *
93  */
94
95 #define WDT_STOP 0x441
96 #define WDT_START 0x443
97
98 /* Default timeout */
99 #define WATCHDOG_TIMEOUT 30             /* 30 seconds +/- 20% */
100 static int timeout = WATCHDOG_TIMEOUT;  /* in seconds */
101 module_param(timeout, int, 0);
102 MODULE_PARM_DESC(timeout,
103         "Watchdog timeout in seconds. 0<= timeout <=30, default="
104                 __MODULE_STRING(WATCHDOG_TIMEOUT) ".");
105
106 static bool nowayout = WATCHDOG_NOWAYOUT;
107 module_param(nowayout, bool, 0);
108 MODULE_PARM_DESC(nowayout,
109                 "Watchdog cannot be stopped once started (default="
110                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
111
112
113 /*
114  *      Watchdog Operations
115  */
116
117 static void ibwdt_ping(void)
118 {
119         int wd_margin = 15 - ((timeout + 1) / 2);
120
121         spin_lock(&ibwdt_lock);
122
123         /* Write a watchdog value */
124         outb_p(wd_margin, WDT_START);
125
126         spin_unlock(&ibwdt_lock);
127 }
128
129 static void ibwdt_disable(void)
130 {
131         spin_lock(&ibwdt_lock);
132         outb_p(0, WDT_STOP);
133         spin_unlock(&ibwdt_lock);
134 }
135
136 static int ibwdt_set_heartbeat(int t)
137 {
138         if (t < 0 || t > 30)
139                 return -EINVAL;
140
141         timeout = t;
142         return 0;
143 }
144
145 /*
146  *      /dev/watchdog handling
147  */
148
149 static ssize_t ibwdt_write(struct file *file, const char __user *buf,
150                                                 size_t count, loff_t *ppos)
151 {
152         if (count) {
153                 if (!nowayout) {
154                         size_t i;
155
156                         /* In case it was set long ago */
157                         expect_close = 0;
158
159                         for (i = 0; i != count; i++) {
160                                 char c;
161                                 if (get_user(c, buf + i))
162                                         return -EFAULT;
163                                 if (c == 'V')
164                                         expect_close = 42;
165                         }
166                 }
167                 ibwdt_ping();
168         }
169         return count;
170 }
171
172 static long ibwdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
173 {
174         int new_margin;
175         void __user *argp = (void __user *)arg;
176         int __user *p = argp;
177
178         static const struct watchdog_info ident = {
179                 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT
180                                                         | WDIOF_MAGICCLOSE,
181                 .firmware_version = 1,
182                 .identity = "IB700 WDT",
183         };
184
185         switch (cmd) {
186         case WDIOC_GETSUPPORT:
187                 if (copy_to_user(argp, &ident, sizeof(ident)))
188                         return -EFAULT;
189                 break;
190
191         case WDIOC_GETSTATUS:
192         case WDIOC_GETBOOTSTATUS:
193                 return put_user(0, p);
194
195         case WDIOC_SETOPTIONS:
196         {
197                 int options, retval = -EINVAL;
198
199                 if (get_user(options, p))
200                         return -EFAULT;
201
202                 if (options & WDIOS_DISABLECARD) {
203                         ibwdt_disable();
204                         retval = 0;
205                 }
206                 if (options & WDIOS_ENABLECARD) {
207                         ibwdt_ping();
208                         retval = 0;
209                 }
210                 return retval;
211         }
212         case WDIOC_KEEPALIVE:
213                 ibwdt_ping();
214                 break;
215
216         case WDIOC_SETTIMEOUT:
217                 if (get_user(new_margin, p))
218                         return -EFAULT;
219                 if (ibwdt_set_heartbeat(new_margin))
220                         return -EINVAL;
221                 ibwdt_ping();
222                 /* Fall */
223
224         case WDIOC_GETTIMEOUT:
225                 return put_user(timeout, p);
226
227         default:
228                 return -ENOTTY;
229         }
230         return 0;
231 }
232
233 static int ibwdt_open(struct inode *inode, struct file *file)
234 {
235         if (test_and_set_bit(0, &ibwdt_is_open))
236                 return -EBUSY;
237         if (nowayout)
238                 __module_get(THIS_MODULE);
239
240         /* Activate */
241         ibwdt_ping();
242         return nonseekable_open(inode, file);
243 }
244
245 static int ibwdt_close(struct inode *inode, struct file *file)
246 {
247         if (expect_close == 42) {
248                 ibwdt_disable();
249         } else {
250                 pr_crit("WDT device closed unexpectedly.  WDT will not stop!\n");
251                 ibwdt_ping();
252         }
253         clear_bit(0, &ibwdt_is_open);
254         expect_close = 0;
255         return 0;
256 }
257
258 /*
259  *      Kernel Interfaces
260  */
261
262 static const struct file_operations ibwdt_fops = {
263         .owner          = THIS_MODULE,
264         .llseek         = no_llseek,
265         .write          = ibwdt_write,
266         .unlocked_ioctl = ibwdt_ioctl,
267         .open           = ibwdt_open,
268         .release        = ibwdt_close,
269 };
270
271 static struct miscdevice ibwdt_miscdev = {
272         .minor = WATCHDOG_MINOR,
273         .name = "watchdog",
274         .fops = &ibwdt_fops,
275 };
276
277 /*
278  *      Init & exit routines
279  */
280
281 static int __devinit ibwdt_probe(struct platform_device *dev)
282 {
283         int res;
284
285 #if WDT_START != WDT_STOP
286         if (!request_region(WDT_STOP, 1, "IB700 WDT")) {
287                 pr_err("STOP method I/O %X is not available\n", WDT_STOP);
288                 res = -EIO;
289                 goto out_nostopreg;
290         }
291 #endif
292
293         if (!request_region(WDT_START, 1, "IB700 WDT")) {
294                 pr_err("START method I/O %X is not available\n", WDT_START);
295                 res = -EIO;
296                 goto out_nostartreg;
297         }
298
299         /* Check that the heartbeat value is within it's range ;
300          * if not reset to the default */
301         if (ibwdt_set_heartbeat(timeout)) {
302                 ibwdt_set_heartbeat(WATCHDOG_TIMEOUT);
303                 pr_info("timeout value must be 0<=x<=30, using %d\n", timeout);
304         }
305
306         res = misc_register(&ibwdt_miscdev);
307         if (res) {
308                 pr_err("failed to register misc device\n");
309                 goto out_nomisc;
310         }
311         return 0;
312
313 out_nomisc:
314         release_region(WDT_START, 1);
315 out_nostartreg:
316 #if WDT_START != WDT_STOP
317         release_region(WDT_STOP, 1);
318 #endif
319 out_nostopreg:
320         return res;
321 }
322
323 static int __devexit ibwdt_remove(struct platform_device *dev)
324 {
325         misc_deregister(&ibwdt_miscdev);
326         release_region(WDT_START, 1);
327 #if WDT_START != WDT_STOP
328         release_region(WDT_STOP, 1);
329 #endif
330         return 0;
331 }
332
333 static void ibwdt_shutdown(struct platform_device *dev)
334 {
335         /* Turn the WDT off if we have a soft shutdown */
336         ibwdt_disable();
337 }
338
339 static struct platform_driver ibwdt_driver = {
340         .probe          = ibwdt_probe,
341         .remove         = __devexit_p(ibwdt_remove),
342         .shutdown       = ibwdt_shutdown,
343         .driver         = {
344                 .owner  = THIS_MODULE,
345                 .name   = DRV_NAME,
346         },
347 };
348
349 static int __init ibwdt_init(void)
350 {
351         int err;
352
353         pr_info("WDT driver for IB700 single board computer initialising\n");
354
355         err = platform_driver_register(&ibwdt_driver);
356         if (err)
357                 return err;
358
359         ibwdt_platform_device = platform_device_register_simple(DRV_NAME,
360                                                                 -1, NULL, 0);
361         if (IS_ERR(ibwdt_platform_device)) {
362                 err = PTR_ERR(ibwdt_platform_device);
363                 goto unreg_platform_driver;
364         }
365
366         return 0;
367
368 unreg_platform_driver:
369         platform_driver_unregister(&ibwdt_driver);
370         return err;
371 }
372
373 static void __exit ibwdt_exit(void)
374 {
375         platform_device_unregister(ibwdt_platform_device);
376         platform_driver_unregister(&ibwdt_driver);
377         pr_info("Watchdog Module Unloaded\n");
378 }
379
380 module_init(ibwdt_init);
381 module_exit(ibwdt_exit);
382
383 MODULE_AUTHOR("Charles Howes <chowes@vsol.net>");
384 MODULE_DESCRIPTION("IB700 SBC watchdog driver");
385 MODULE_LICENSE("GPL");
386 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
387
388 /* end of ib700wdt.c */