drivers/watchdog/acquirewdt.c

   1 /*
   2  *      Acquire Single Board Computer Watchdog Timer driver
   3  *
   4  *      Based on wdt.c. Original copyright messages:
   5  *
   6  *      (c) Copyright 1996 Alan Cox <alan@redhat.com>, All Rights Reserved.
   7  *                              http://www.redhat.com
   8  *
   9  *      This program is free software; you can redistribute it and/or
  10  *      modify it under the terms of the GNU General Public License
  11  *      as published by the Free Software Foundation; either version
  12  *      2 of the License, or (at your option) any later version.
  13  *
  14  *      Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
  15  *      warranty for any of this software. This material is provided
  16  *      "AS-IS" and at no charge.
  17  *
  18  *      (c) Copyright 1995    Alan Cox <alan@redhat.com>
  19  *
  20  *      14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
  21  *          Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
  22  *          Can't add timeout - driver doesn't allow changing value
  23  */
  24
  25 /*
  26  *      Theory of Operation:
  27  *              The Watch-Dog Timer is provided to ensure that standalone
  28  *              Systems can always recover from catastrophic conditions that
  29  *              caused the CPU to crash. This condition may have occured by
  30  *              external EMI or a software bug. When the CPU stops working
  31  *              correctly, hardware on the board will either perform a hardware
  32  *              reset (cold boot) or a non-maskable interrupt (NMI) to bring the
  33  *              system back to a known state.
  34  *
  35  *              The Watch-Dog Timer is controlled by two I/O Ports.
  36  *                443 hex       - Read  - Enable or refresh the Watch-Dog Timer
  37  *                043 hex       - Read  - Disable the Watch-Dog Timer
  38  *
  39  *              To enable the Watch-Dog Timer, a read from I/O port 443h must
  40  *              be performed. This will enable and activate the countdown timer
  41  *              which will eventually time out and either reset the CPU or cause
  42  *              an NMI depending on the setting of a jumper. To ensure that this
  43  *              reset condition does not occur, the Watch-Dog Timer must be
  44  *              periodically refreshed by reading the same I/O port 443h.
  45  *              The Watch-Dog Timer is disabled by reading I/O port 043h.
  46  *
  47  *              The Watch-Dog Timer Time-Out Period is set via jumpers.
  48  *              It can be 1, 2, 10, 20, 110 or 220 seconds.
  49  */
  50
  51 /*
  52  *      Includes, defines, variables, module parameters, ...
  53  */
  54
  55 /* Includes */
  56 #include <linux/module.h>               /* For module specific items */
  57 #include <linux/moduleparam.h>          /* For new moduleparam's */
  58 #include <linux/types.h>                /* For standard types (like size_t) */
  59 #include <linux/errno.h>                /* For the -ENODEV/... values */
  60 #include <linux/kernel.h>               /* For printk/panic/... */
  61 #include <linux/miscdevice.h>           /* For MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR) */
  62 #include <linux/watchdog.h>             /* For the watchdog specific items */
  63 #include <linux/fs.h>                   /* For file operations */
  64 #include <linux/ioport.h>               /* For io-port access */
  65 #include <linux/platform_device.h>      /* For platform_driver framework */
  66 #include <linux/init.h>                 /* For __init/__exit/... */
  67
  68 #include <asm/uaccess.h>                /* For copy_to_user/put_user/... */
  69 #include <asm/io.h>                     /* For inb/outb/... */
  70
  71 /* Module information */
  72 #define DRV_NAME "acquirewdt"
  73 #define PFX DRV_NAME ": "
  74 #define WATCHDOG_NAME "Acquire WDT"
  75 #define WATCHDOG_HEARTBEAT 0    /* There is no way to see what the correct time-out period is */
  76
  77 /* internal variables */
  78 static struct platform_device *acq_platform_device;     /* the watchdog platform device */
  79 static unsigned long acq_is_open;
  80 static char expect_close;
  81
  82 /* module parameters */
  83 static int wdt_stop = 0x43;     /* You must set this - there is no sane way to probe for this board. */
  84 module_param(wdt_stop, int, 0);
  85 MODULE_PARM_DESC(wdt_stop, "Acquire WDT 'stop' io port (default 0x43)");
  86
  87 static int wdt_start = 0x443;   /* You must set this - there is no sane way to probe for this board. */
  88 module_param(wdt_start, int, 0);
  89 MODULE_PARM_DESC(wdt_start, "Acquire WDT 'start' io port (default 0x443)");
  90
  91 static int nowayout = WATCHDOG_NOWAYOUT;
  92 module_param(nowayout, int, 0);
  93 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  94
  95 /*
  96  *      Watchdog Operations
  97  */
  98
  99 static void acq_keepalive(void)
 100 {
 101         /* Write a watchdog value */
 102         inb_p(wdt_start);
 103 }
 104
 105 static void acq_stop(void)
 106 {
 107         /* Turn the card off */
 108         inb_p(wdt_stop);
 109 }
 110
 111 /*
 112  *      /dev/watchdog handling
 113  */
 114
 115 static ssize_t acq_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
 116 {
 117         /* See if we got the magic character 'V' and reload the timer */
 118         if(count) {
 119                 if (!nowayout) {
 120                         size_t i;
 121
 122                         /* note: just in case someone wrote the magic character
 123                          * five months ago... */
 124                         expect_close = 0;
 125
 126                         /* scan to see whether or not we got the magic character */
 127                         for (i = 0; i != count; i++) {
 128                                 char c;
 129                                 if (get_user(c, buf + i))
 130                                         return -EFAULT;
 131                                 if (c == 'V')
 132                                         expect_close = 42;
 133                         }
 134                 }
 135
 136                 /* Well, anyhow someone wrote to us, we should return that favour */
 137                 acq_keepalive();
 138         }
 139         return count;
 140 }
 141
 142 static int acq_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 143         unsigned long arg)
 144 {
 145         int options, retval = -EINVAL;
 146         void __user *argp = (void __user *)arg;
 147         int __user *p = argp;
 148         static struct watchdog_info ident =
 149         {
 150                 .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 151                 .firmware_version = 1,
 152                 .identity = WATCHDOG_NAME,
 153         };
 154
 155         switch(cmd)
 156         {
 157         case WDIOC_GETSUPPORT:
 158           return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
 159
 160         case WDIOC_GETSTATUS:
 161         case WDIOC_GETBOOTSTATUS:
 162           return put_user(0, p);
 163
 164         case WDIOC_KEEPALIVE:
 165           acq_keepalive();
 166           return 0;
 167
 168         case WDIOC_GETTIMEOUT:
 169           return put_user(WATCHDOG_HEARTBEAT, p);
 170
 171         case WDIOC_SETOPTIONS:
 172         {
 173             if (get_user(options, p))
 174               return -EFAULT;
 175
 176             if (options & WDIOS_DISABLECARD)
 177             {
 178               acq_stop();
 179               retval = 0;
 180             }
 181
 182             if (options & WDIOS_ENABLECARD)
 183             {
 184               acq_keepalive();
 185               retval = 0;
 186             }
 187
 188             return retval;
 189         }
 190
 191         default:
 192           return -ENOTTY;
 193         }
 194 }
 195
 196 static int acq_open(struct inode *inode, struct file *file)
 197 {
 198         if (test_and_set_bit(0, &acq_is_open))
 199                 return -EBUSY;
 200
 201         if (nowayout)
 202                 __module_get(THIS_MODULE);
 203
 204         /* Activate */
 205         acq_keepalive();
 206         return nonseekable_open(inode, file);
 207 }
 208
 209 static int acq_close(struct inode *inode, struct file *file)
 210 {
 211         if (expect_close == 42) {
 212                 acq_stop();
 213         } else {
 214                 printk(KERN_CRIT PFX "Unexpected close, not stopping watchdog!\n");
 215                 acq_keepalive();
 216         }
 217         clear_bit(0, &acq_is_open);
 218         expect_close = 0;
 219         return 0;
 220 }
 221
 222 /*
 223  *      Kernel Interfaces
 224  */
 225
 226 static const struct file_operations acq_fops = {
 227         .owner          = THIS_MODULE,
 228         .llseek         = no_llseek,
 229         .write          = acq_write,
 230         .ioctl          = acq_ioctl,
 231         .open           = acq_open,
 232         .release        = acq_close,
 233 };
 234
 235 static struct miscdevice acq_miscdev = {
 236         .minor  = WATCHDOG_MINOR,
 237         .name   = "watchdog",
 238         .fops   = &acq_fops,
 239 };
 240
 241 /*
 242  *      Init & exit routines
 243  */
 244
 245 static int __devinit acq_probe(struct platform_device *dev)
 246 {
 247         int ret;
 248
 249         if (wdt_stop != wdt_start) {
 250                 if (!request_region(wdt_stop, 1, WATCHDOG_NAME)) {
 251                         printk (KERN_ERR PFX "I/O address 0x%04x already in use\n",
 252                                 wdt_stop);
 253                         ret = -EIO;
 254                         goto out;
 255                 }
 256         }
 257
 258         if (!request_region(wdt_start, 1, WATCHDOG_NAME)) {
 259                 printk (KERN_ERR PFX "I/O address 0x%04x already in use\n",
 260                         wdt_start);
 261                 ret = -EIO;
 262                 goto unreg_stop;
 263         }
 264
 265         ret = misc_register(&acq_miscdev);
 266         if (ret != 0) {
 267                 printk (KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n",
 268                         WATCHDOG_MINOR, ret);
 269                 goto unreg_regions;
 270         }
 271
 272         printk (KERN_INFO PFX "initialized. (nowayout=%d)\n",
 273                 nowayout);
 274
 275         return 0;
 276
 277 unreg_regions:
 278         release_region(wdt_start, 1);
 279 unreg_stop:
 280         if (wdt_stop != wdt_start)
 281                 release_region(wdt_stop, 1);
 282 out:
 283         return ret;
 284 }
 285
 286 static int __devexit acq_remove(struct platform_device *dev)
 287 {
 288         misc_deregister(&acq_miscdev);
 289         release_region(wdt_start,1);
 290         if(wdt_stop != wdt_start)
 291                 release_region(wdt_stop,1);
 292
 293         return 0;
 294 }
 295
 296 static void acq_shutdown(struct platform_device *dev)
 297 {
 298         /* Turn the WDT off if we have a soft shutdown */
 299         acq_stop();
 300 }
 301
 302 static struct platform_driver acquirewdt_driver = {
 303         .probe          = acq_probe,
 304         .remove         = __devexit_p(acq_remove),
 305         .shutdown       = acq_shutdown,
 306         .driver         = {
 307                 .owner  = THIS_MODULE,
 308                 .name   = DRV_NAME,
 309         },
 310 };
 311
 312 static int __init acq_init(void)
 313 {
 314         int err;
 315
 316         printk(KERN_INFO "WDT driver for Acquire single board computer initialising.\n");
 317
 318         err = platform_driver_register(&acquirewdt_driver);
 319         if (err)
 320                 return err;
 321
 322         acq_platform_device = platform_device_register_simple(DRV_NAME, -1, NULL, 0);
 323         if (IS_ERR(acq_platform_device)) {
 324                 err = PTR_ERR(acq_platform_device);
 325                 goto unreg_platform_driver;
 326         }
 327
 328         return 0;
 329
 330 unreg_platform_driver:
 331         platform_driver_unregister(&acquirewdt_driver);
 332         return err;
 333 }
 334
 335 static void __exit acq_exit(void)
 336 {
 337         platform_device_unregister(acq_platform_device);
 338         platform_driver_unregister(&acquirewdt_driver);
 339         printk(KERN_INFO PFX "Watchdog Module Unloaded.\n");
 340 }
 341
 342 module_init(acq_init);
 343 module_exit(acq_exit);
 344
 345 MODULE_AUTHOR("David Woodhouse");
 346 MODULE_DESCRIPTION("Acquire Inc. Single Board Computer Watchdog Timer driver");
 347 MODULE_LICENSE("GPL");
 348 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);