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

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