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@lxorguk.ukuu.org.uk>,
   7  *                                              All Rights Reserved.
   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@lxorguk.ukuu.org.uk>
  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 occurred 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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  56
  57 /* Includes */
  58 #include <linux/module.h>               /* For module specific items */
  59 #include <linux/moduleparam.h>          /* For new moduleparam's */
  60 #include <linux/types.h>                /* For standard types (like size_t) */
  61 #include <linux/errno.h>                /* For the -ENODEV/... values */
  62 #include <linux/kernel.h>               /* For printk/panic/... */
  63 #include <linux/miscdevice.h>           /* For MODULE_ALIAS_MISCDEV
  64                                                         (WATCHDOG_MINOR) */
  65 #include <linux/watchdog.h>             /* For the watchdog specific items */
  66 #include <linux/fs.h>                   /* For file operations */
  67 #include <linux/ioport.h>               /* For io-port access */
  68 #include <linux/platform_device.h>      /* For platform_driver framework */
  69 #include <linux/init.h>                 /* For __init/__exit/... */
  70 #include <linux/uaccess.h>              /* For copy_to_user/put_user/... */
  71 #include <linux/io.h>                   /* For inb/outb/... */
  72
  73 /* Module information */
  74 #define DRV_NAME "acquirewdt"
  75 #define WATCHDOG_NAME "Acquire WDT"
  76 /* There is no way to see what the correct time-out period is */
  77 #define WATCHDOG_HEARTBEAT 0
  78
  79 /* internal variables */
  80 /* the watchdog platform device */
  81 static struct platform_device *acq_platform_device;
  82 static unsigned long acq_is_open;
  83 static char expect_close;
  84
  85 /* module parameters */
  86 /* You must set this - there is no sane way to probe for this board. */
  87 static int wdt_stop = 0x43;
  88 module_param(wdt_stop, int, 0);
  89 MODULE_PARM_DESC(wdt_stop, "Acquire WDT 'stop' io port (default 0x43)");
  90
  91 /* You must set this - there is no sane way to probe for this board. */
  92 static int wdt_start = 0x443;
  93 module_param(wdt_start, int, 0);
  94 MODULE_PARM_DESC(wdt_start, "Acquire WDT 'start' io port (default 0x443)");
  95
  96 static bool nowayout = WATCHDOG_NOWAYOUT;
  97 module_param(nowayout, bool, 0);
  98 MODULE_PARM_DESC(nowayout,
  99         "Watchdog cannot be stopped once started (default="
 100         __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 101
 102 /*
 103  *      Watchdog Operations
 104  */
 105
 106 static void acq_keepalive(void)
 107 {
 108         /* Write a watchdog value */
 109         inb_p(wdt_start);
 110 }
 111
 112 static void acq_stop(void)
 113 {
 114         /* Turn the card off */
 115         inb_p(wdt_stop);
 116 }
 117
 118 /*
 119  *      /dev/watchdog handling
 120  */
 121
 122 static ssize_t acq_write(struct file *file, const char __user *buf,
 123                                                 size_t count, loff_t *ppos)
 124 {
 125         /* See if we got the magic character 'V' and reload the timer */
 126         if (count) {
 127                 if (!nowayout) {
 128                         size_t i;
 129                         /* note: just in case someone wrote the magic character
 130                            five months ago... */
 131                         expect_close = 0;
 132                         /* scan to see whether or not we got the
 133                            magic character */
 134                         for (i = 0; i != count; i++) {
 135                                 char c;
 136                                 if (get_user(c, buf + i))
 137                                         return -EFAULT;
 138                                 if (c == 'V')
 139                                         expect_close = 42;
 140                         }
 141                 }
 142                 /* Well, anyhow someone wrote to us, we should
 143                                 return that favour */
 144                 acq_keepalive();
 145         }
 146         return count;
 147 }
 148
 149 static long acq_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 150 {
 151         int options, retval = -EINVAL;
 152         void __user *argp = (void __user *)arg;
 153         int __user *p = argp;
 154         static const struct watchdog_info ident = {
 155                 .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 156                 .firmware_version = 1,
 157                 .identity = WATCHDOG_NAME,
 158         };
 159
 160         switch (cmd) {
 161         case WDIOC_GETSUPPORT:
 162                 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
 163
 164         case WDIOC_GETSTATUS:
 165         case WDIOC_GETBOOTSTATUS:
 166                 return put_user(0, p);
 167
 168         case WDIOC_SETOPTIONS:
 169         {
 170                 if (get_user(options, p))
 171                         return -EFAULT;
 172                 if (options & WDIOS_DISABLECARD) {
 173                         acq_stop();
 174                         retval = 0;
 175                 }
 176                 if (options & WDIOS_ENABLECARD) {
 177                         acq_keepalive();
 178                         retval = 0;
 179                 }
 180                 return retval;
 181         }
 182         case WDIOC_KEEPALIVE:
 183                 acq_keepalive();
 184                 return 0;
 185
 186         case WDIOC_GETTIMEOUT:
 187                 return put_user(WATCHDOG_HEARTBEAT, p);
 188
 189         default:
 190                 return -ENOTTY;
 191         }
 192 }
 193
 194 static int acq_open(struct inode *inode, struct file *file)
 195 {
 196         if (test_and_set_bit(0, &acq_is_open))
 197                 return -EBUSY;
 198
 199         if (nowayout)
 200                 __module_get(THIS_MODULE);
 201
 202         /* Activate */
 203         acq_keepalive();
 204         return nonseekable_open(inode, file);
 205 }
 206
 207 static int acq_close(struct inode *inode, struct file *file)
 208 {
 209         if (expect_close == 42) {
 210                 acq_stop();
 211         } else {
 212                 pr_crit("Unexpected close, not stopping watchdog!\n");
 213                 acq_keepalive();
 214         }
 215         clear_bit(0, &acq_is_open);
 216         expect_close = 0;
 217         return 0;
 218 }
 219
 220 /*
 221  *      Kernel Interfaces
 222  */
 223
 224 static const struct file_operations acq_fops = {
 225         .owner          = THIS_MODULE,
 226         .llseek         = no_llseek,
 227         .write          = acq_write,
 228         .unlocked_ioctl = acq_ioctl,
 229         .open           = acq_open,
 230         .release        = acq_close,
 231 };
 232
 233 static struct miscdevice acq_miscdev = {
 234         .minor  = WATCHDOG_MINOR,
 235         .name   = "watchdog",
 236         .fops   = &acq_fops,
 237 };
 238
 239 /*
 240  *      Init & exit routines
 241  */
 242
 243 static int acq_probe(struct platform_device *dev)
 244 {
 245         int ret;
 246
 247         if (wdt_stop != wdt_start) {
 248                 if (!request_region(wdt_stop, 1, WATCHDOG_NAME)) {
 249                         pr_err("I/O address 0x%04x already in use\n", wdt_stop);
 250                         ret = -EIO;
 251                         goto out;
 252                 }
 253         }
 254
 255         if (!request_region(wdt_start, 1, WATCHDOG_NAME)) {
 256                 pr_err("I/O address 0x%04x already in use\n", wdt_start);
 257                 ret = -EIO;
 258                 goto unreg_stop;
 259         }
 260         ret = misc_register(&acq_miscdev);
 261         if (ret != 0) {
 262                 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
 263                        WATCHDOG_MINOR, ret);
 264                 goto unreg_regions;
 265         }
 266         pr_info("initialized. (nowayout=%d)\n", nowayout);
 267
 268         return 0;
 269 unreg_regions:
 270         release_region(wdt_start, 1);
 271 unreg_stop:
 272         if (wdt_stop != wdt_start)
 273                 release_region(wdt_stop, 1);
 274 out:
 275         return ret;
 276 }
 277
 278 static int acq_remove(struct platform_device *dev)
 279 {
 280         misc_deregister(&acq_miscdev);
 281         release_region(wdt_start, 1);
 282         if (wdt_stop != wdt_start)
 283                 release_region(wdt_stop, 1);
 284
 285         return 0;
 286 }
 287
 288 static void acq_shutdown(struct platform_device *dev)
 289 {
 290         /* Turn the WDT off if we have a soft shutdown */
 291         acq_stop();
 292 }
 293
 294 static struct platform_driver acquirewdt_driver = {
 295         .probe          = acq_probe,
 296         .remove         = acq_remove,
 297         .shutdown       = acq_shutdown,
 298         .driver         = {
 299                 .owner  = THIS_MODULE,
 300                 .name   = DRV_NAME,
 301         },
 302 };
 303
 304 static int __init acq_init(void)
 305 {
 306         int err;
 307
 308         pr_info("WDT driver for Acquire single board computer initialising\n");
 309
 310         err = platform_driver_register(&acquirewdt_driver);
 311         if (err)
 312                 return err;
 313
 314         acq_platform_device = platform_device_register_simple(DRV_NAME,
 315                                                                 -1, NULL, 0);
 316         if (IS_ERR(acq_platform_device)) {
 317                 err = PTR_ERR(acq_platform_device);
 318                 goto unreg_platform_driver;
 319         }
 320         return 0;
 321
 322 unreg_platform_driver:
 323         platform_driver_unregister(&acquirewdt_driver);
 324         return err;
 325 }
 326
 327 static void __exit acq_exit(void)
 328 {
 329         platform_device_unregister(acq_platform_device);
 330         platform_driver_unregister(&acquirewdt_driver);
 331         pr_info("Watchdog Module Unloaded\n");
 332 }
 333
 334 module_init(acq_init);
 335 module_exit(acq_exit);
 336
 337 MODULE_AUTHOR("David Woodhouse");
 338 MODULE_DESCRIPTION("Acquire Inc. Single Board Computer Watchdog Timer driver");
 339 MODULE_LICENSE("GPL");
 340 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);