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