drivers/watchdog/wafer5823wdt.c

   1 /*
   2  *      ICP Wafer 5823 Single Board Computer WDT driver
   3  *      http://www.icpamerica.com/wafer_5823.php
   4  *      May also work on other similar models
   5  *
   6  *      (c) Copyright 2002 Justin Cormack <justin@street-vision.com>
   7  *
   8  *      Release 0.02
   9  *
  10  *      Based on advantechwdt.c which is based on wdt.c.
  11  *      Original copyright messages:
  12  *
  13  *      (c) Copyright 1996-1997 Alan Cox <alan@lxorguk.ukuu.org.uk>,
  14  *                                              All Rights Reserved.
  15  *
  16  *      This program is free software; you can redistribute it and/or
  17  *      modify it under the terms of the GNU General Public License
  18  *      as published by the Free Software Foundation; either version
  19  *      2 of the License, or (at your option) any later version.
  20  *
  21  *      Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
  22  *      warranty for any of this software. This material is provided
  23  *      "AS-IS" and at no charge.
  24  *
  25  *      (c) Copyright 1995    Alan Cox <alan@lxorguk.ukuu.org.uk>
  26  *
  27  */
  28
  29 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  30
  31 #include <linux/module.h>
  32 #include <linux/moduleparam.h>
  33 #include <linux/miscdevice.h>
  34 #include <linux/watchdog.h>
  35 #include <linux/fs.h>
  36 #include <linux/ioport.h>
  37 #include <linux/notifier.h>
  38 #include <linux/reboot.h>
  39 #include <linux/init.h>
  40 #include <linux/spinlock.h>
  41 #include <linux/io.h>
  42 #include <linux/uaccess.h>
  43
  44 #define WATCHDOG_NAME "Wafer 5823 WDT"
  45 #define PFX WATCHDOG_NAME ": "
  46 #define WD_TIMO 60                      /* 60 sec default timeout */
  47
  48 static unsigned long wafwdt_is_open;
  49 static char expect_close;
  50 static DEFINE_SPINLOCK(wafwdt_lock);
  51
  52 /*
  53  *      You must set these - there is no sane way to probe for this board.
  54  *
  55  *      To enable, write the timeout value in seconds (1 to 255) to I/O
  56  *      port WDT_START, then read the port to start the watchdog. To pat
  57  *      the dog, read port WDT_STOP to stop the timer, then read WDT_START
  58  *      to restart it again.
  59  */
  60
  61 static int wdt_stop = 0x843;
  62 static int wdt_start = 0x443;
  63
  64 static int timeout = WD_TIMO;  /* in seconds */
  65 module_param(timeout, int, 0);
  66 MODULE_PARM_DESC(timeout,
  67                 "Watchdog timeout in seconds. 1 <= timeout <= 255, default="
  68                                 __MODULE_STRING(WD_TIMO) ".");
  69
  70 static bool nowayout = WATCHDOG_NOWAYOUT;
  71 module_param(nowayout, bool, 0);
  72 MODULE_PARM_DESC(nowayout,
  73                 "Watchdog cannot be stopped once started (default="
  74                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  75
  76 static void wafwdt_ping(void)
  77 {
  78         /* pat watchdog */
  79         spin_lock(&wafwdt_lock);
  80         inb_p(wdt_stop);
  81         inb_p(wdt_start);
  82         spin_unlock(&wafwdt_lock);
  83 }
  84
  85 static void wafwdt_start(void)
  86 {
  87         /* start up watchdog */
  88         outb_p(timeout, wdt_start);
  89         inb_p(wdt_start);
  90 }
  91
  92 static void wafwdt_stop(void)
  93 {
  94         /* stop watchdog */
  95         inb_p(wdt_stop);
  96 }
  97
  98 static ssize_t wafwdt_write(struct file *file, const char __user *buf,
  99                                                 size_t count, loff_t *ppos)
 100 {
 101         /* See if we got the magic character 'V' and reload the timer */
 102         if (count) {
 103                 if (!nowayout) {
 104                         size_t i;
 105
 106                         /* In case it was set long ago */
 107                         expect_close = 0;
 108
 109                         /* scan to see whether or not we got the magic
 110                            character */
 111                         for (i = 0; i != count; i++) {
 112                                 char c;
 113                                 if (get_user(c, buf + i))
 114                                         return -EFAULT;
 115                                 if (c == 'V')
 116                                         expect_close = 42;
 117                         }
 118                 }
 119                 /* Well, anyhow someone wrote to us, we should
 120                    return that favour */
 121                 wafwdt_ping();
 122         }
 123         return count;
 124 }
 125
 126 static long wafwdt_ioctl(struct file *file, unsigned int cmd,
 127                                                         unsigned long arg)
 128 {
 129         int new_timeout;
 130         void __user *argp = (void __user *)arg;
 131         int __user *p = argp;
 132         static const struct watchdog_info ident = {
 133                 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
 134                                                         WDIOF_MAGICCLOSE,
 135                 .firmware_version = 1,
 136                 .identity = "Wafer 5823 WDT",
 137         };
 138
 139         switch (cmd) {
 140         case WDIOC_GETSUPPORT:
 141                 if (copy_to_user(argp, &ident, sizeof(ident)))
 142                         return -EFAULT;
 143                 break;
 144
 145         case WDIOC_GETSTATUS:
 146         case WDIOC_GETBOOTSTATUS:
 147                 return put_user(0, p);
 148
 149         case WDIOC_SETOPTIONS:
 150         {
 151                 int options, retval = -EINVAL;
 152
 153                 if (get_user(options, p))
 154                         return -EFAULT;
 155
 156                 if (options & WDIOS_DISABLECARD) {
 157                         wafwdt_stop();
 158                         retval = 0;
 159                 }
 160
 161                 if (options & WDIOS_ENABLECARD) {
 162                         wafwdt_start();
 163                         retval = 0;
 164                 }
 165
 166                 return retval;
 167         }
 168
 169         case WDIOC_KEEPALIVE:
 170                 wafwdt_ping();
 171                 break;
 172
 173         case WDIOC_SETTIMEOUT:
 174                 if (get_user(new_timeout, p))
 175                         return -EFAULT;
 176                 if ((new_timeout < 1) || (new_timeout > 255))
 177                         return -EINVAL;
 178                 timeout = new_timeout;
 179                 wafwdt_stop();
 180                 wafwdt_start();
 181                 /* Fall */
 182         case WDIOC_GETTIMEOUT:
 183                 return put_user(timeout, p);
 184
 185         default:
 186                 return -ENOTTY;
 187         }
 188         return 0;
 189 }
 190
 191 static int wafwdt_open(struct inode *inode, struct file *file)
 192 {
 193         if (test_and_set_bit(0, &wafwdt_is_open))
 194                 return -EBUSY;
 195
 196         /*
 197          *      Activate
 198          */
 199         wafwdt_start();
 200         return nonseekable_open(inode, file);
 201 }
 202
 203 static int wafwdt_close(struct inode *inode, struct file *file)
 204 {
 205         if (expect_close == 42)
 206                 wafwdt_stop();
 207         else {
 208                 pr_crit("WDT device closed unexpectedly.  WDT will not stop!\n");
 209                 wafwdt_ping();
 210         }
 211         clear_bit(0, &wafwdt_is_open);
 212         expect_close = 0;
 213         return 0;
 214 }
 215
 216 /*
 217  *      Notifier for system down
 218  */
 219
 220 static int wafwdt_notify_sys(struct notifier_block *this, unsigned long code,
 221                                                                 void *unused)
 222 {
 223         if (code == SYS_DOWN || code == SYS_HALT)
 224                 wafwdt_stop();
 225         return NOTIFY_DONE;
 226 }
 227
 228 /*
 229  *      Kernel Interfaces
 230  */
 231
 232 static const struct file_operations wafwdt_fops = {
 233         .owner          = THIS_MODULE,
 234         .llseek         = no_llseek,
 235         .write          = wafwdt_write,
 236         .unlocked_ioctl = wafwdt_ioctl,
 237         .open           = wafwdt_open,
 238         .release        = wafwdt_close,
 239 };
 240
 241 static struct miscdevice wafwdt_miscdev = {
 242         .minor  = WATCHDOG_MINOR,
 243         .name   = "watchdog",
 244         .fops   = &wafwdt_fops,
 245 };
 246
 247 /*
 248  *      The WDT needs to learn about soft shutdowns in order to
 249  *      turn the timebomb registers off.
 250  */
 251
 252 static struct notifier_block wafwdt_notifier = {
 253         .notifier_call = wafwdt_notify_sys,
 254 };
 255
 256 static int __init wafwdt_init(void)
 257 {
 258         int ret;
 259
 260         pr_info("WDT driver for Wafer 5823 single board computer initialising\n");
 261
 262         if (timeout < 1 || timeout > 255) {
 263                 timeout = WD_TIMO;
 264                 pr_info("timeout value must be 1 <= x <= 255, using %d\n",
 265                         timeout);
 266         }
 267
 268         if (wdt_stop != wdt_start) {
 269                 if (!request_region(wdt_stop, 1, "Wafer 5823 WDT")) {
 270                         pr_err("I/O address 0x%04x already in use\n", wdt_stop);
 271                         ret = -EIO;
 272                         goto error;
 273                 }
 274         }
 275
 276         if (!request_region(wdt_start, 1, "Wafer 5823 WDT")) {
 277                 pr_err("I/O address 0x%04x already in use\n", wdt_start);
 278                 ret = -EIO;
 279                 goto error2;
 280         }
 281
 282         ret = register_reboot_notifier(&wafwdt_notifier);
 283         if (ret != 0) {
 284                 pr_err("cannot register reboot notifier (err=%d)\n", ret);
 285                 goto error3;
 286         }
 287
 288         ret = misc_register(&wafwdt_miscdev);
 289         if (ret != 0) {
 290                 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
 291                        WATCHDOG_MINOR, ret);
 292                 goto error4;
 293         }
 294
 295         pr_info("initialized. timeout=%d sec (nowayout=%d)\n",
 296                 timeout, nowayout);
 297
 298         return ret;
 299 error4:
 300         unregister_reboot_notifier(&wafwdt_notifier);
 301 error3:
 302         release_region(wdt_start, 1);
 303 error2:
 304         if (wdt_stop != wdt_start)
 305                 release_region(wdt_stop, 1);
 306 error:
 307         return ret;
 308 }
 309
 310 static void __exit wafwdt_exit(void)
 311 {
 312         misc_deregister(&wafwdt_miscdev);
 313         unregister_reboot_notifier(&wafwdt_notifier);
 314         if (wdt_stop != wdt_start)
 315                 release_region(wdt_stop, 1);
 316         release_region(wdt_start, 1);
 317 }
 318
 319 module_init(wafwdt_init);
 320 module_exit(wafwdt_exit);
 321
 322 MODULE_AUTHOR("Justin Cormack");
 323 MODULE_DESCRIPTION("ICP Wafer 5823 Single Board Computer WDT driver");
 324 MODULE_LICENSE("GPL");
 325
 326 /* end of wafer5823wdt.c */