drivers/watchdog/sbc60xxwdt.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *      60xx Single Board Computer Watchdog Timer driver for Linux 2.2.x
   4  *
   5  *      Based on acquirewdt.c by Alan Cox.
   6  *
   7  *      The author does NOT admit liability nor provide warranty for
   8  *      any of this software. This material is provided "AS-IS" in
   9  *      the hope that it may be useful for others.
  10  *
  11  *      (c) Copyright 2000    Jakob Oestergaard <jakob@unthought.net>
  12  *
  13  *           12/4 - 2000      [Initial revision]
  14  *           25/4 - 2000      Added /dev/watchdog support
  15  *           09/5 - 2001      [smj@oro.net] fixed fop_write to "return 1"
  16  *                                      on success
  17  *           12/4 - 2002      [rob@osinvestor.com] eliminate fop_read
  18  *                            fix possible wdt_is_open race
  19  *                            add CONFIG_WATCHDOG_NOWAYOUT support
  20  *                            remove lock_kernel/unlock_kernel pairs
  21  *                            added KERN_* to printk's
  22  *                            got rid of extraneous comments
  23  *                            changed watchdog_info to correctly reflect what
  24  *                            the driver offers
  25  *                            added WDIOC_GETSTATUS, WDIOC_GETBOOTSTATUS,
  26  *                            WDIOC_SETTIMEOUT, WDIOC_GETTIMEOUT, and
  27  *                            WDIOC_SETOPTIONS ioctls
  28  *           09/8 - 2003      [wim@iguana.be] cleanup of trailing spaces
  29  *                            use module_param
  30  *                            made timeout (the emulated heartbeat) a
  31  *                            module_param
  32  *                            made the keepalive ping an internal subroutine
  33  *                            made wdt_stop and wdt_start module params
  34  *                            added extra printk's for startup problems
  35  *                            added MODULE_AUTHOR and MODULE_DESCRIPTION info
  36  *
  37  *  This WDT driver is different from the other Linux WDT
  38  *  drivers in the following ways:
  39  *  *)  The driver will ping the watchdog by itself, because this
  40  *      particular WDT has a very short timeout (one second) and it
  41  *      would be insane to count on any userspace daemon always
  42  *      getting scheduled within that time frame.
  43  */
  44
  45 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  46
  47 #include <linux/module.h>
  48 #include <linux/moduleparam.h>
  49 #include <linux/types.h>
  50 #include <linux/timer.h>
  51 #include <linux/jiffies.h>
  52 #include <linux/miscdevice.h>
  53 #include <linux/watchdog.h>
  54 #include <linux/fs.h>
  55 #include <linux/ioport.h>
  56 #include <linux/notifier.h>
  57 #include <linux/reboot.h>
  58 #include <linux/init.h>
  59 #include <linux/io.h>
  60 #include <linux/uaccess.h>
  61
  62
  63 #define OUR_NAME "sbc60xxwdt"
  64 #define PFX OUR_NAME ": "
  65
  66 /*
  67  * You must set these - The driver cannot probe for the settings
  68  */
  69
  70 static int wdt_stop = 0x45;
  71 module_param(wdt_stop, int, 0);
  72 MODULE_PARM_DESC(wdt_stop, "SBC60xx WDT 'stop' io port (default 0x45)");
  73
  74 static int wdt_start = 0x443;
  75 module_param(wdt_start, int, 0);
  76 MODULE_PARM_DESC(wdt_start, "SBC60xx WDT 'start' io port (default 0x443)");
  77
  78 /*
  79  * The 60xx board can use watchdog timeout values from one second
  80  * to several minutes.  The default is one second, so if we reset
  81  * the watchdog every ~250ms we should be safe.
  82  */
  83
  84 #define WDT_INTERVAL (HZ/4+1)
  85
  86 /*
  87  * We must not require too good response from the userspace daemon.
  88  * Here we require the userspace daemon to send us a heartbeat
  89  * char to /dev/watchdog every 30 seconds.
  90  * If the daemon pulses us every 25 seconds, we can still afford
  91  * a 5 second scheduling delay on the (high priority) daemon. That
  92  * should be sufficient for a box under any load.
  93  */
  94
  95 #define WATCHDOG_TIMEOUT 30             /* 30 sec default timeout */
  96 static int timeout = WATCHDOG_TIMEOUT;  /* in seconds, multiplied by HZ to
  97                                            get seconds to wait for a ping */
  98 module_param(timeout, int, 0);
  99 MODULE_PARM_DESC(timeout,
 100         "Watchdog timeout in seconds. (1<=timeout<=3600, default="
 101                                 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
 102
 103 static bool nowayout = WATCHDOG_NOWAYOUT;
 104 module_param(nowayout, bool, 0);
 105 MODULE_PARM_DESC(nowayout,
 106         "Watchdog cannot be stopped once started (default="
 107                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 108
 109 static void wdt_timer_ping(struct timer_list *);
 110 static DEFINE_TIMER(timer, wdt_timer_ping);
 111 static unsigned long next_heartbeat;
 112 static unsigned long wdt_is_open;
 113 static char wdt_expect_close;
 114
 115 /*
 116  *      Whack the dog
 117  */
 118
 119 static void wdt_timer_ping(struct timer_list *unused)
 120 {
 121         /* If we got a heartbeat pulse within the WDT_US_INTERVAL
 122          * we agree to ping the WDT
 123          */
 124         if (time_before(jiffies, next_heartbeat)) {
 125                 /* Ping the WDT by reading from wdt_start */
 126                 inb_p(wdt_start);
 127                 /* Re-set the timer interval */
 128                 mod_timer(&timer, jiffies + WDT_INTERVAL);
 129         } else
 130                 pr_warn("Heartbeat lost! Will not ping the watchdog\n");
 131 }
 132
 133 /*
 134  * Utility routines
 135  */
 136
 137 static void wdt_startup(void)
 138 {
 139         next_heartbeat = jiffies + (timeout * HZ);
 140
 141         /* Start the timer */
 142         mod_timer(&timer, jiffies + WDT_INTERVAL);
 143         pr_info("Watchdog timer is now enabled\n");
 144 }
 145
 146 static void wdt_turnoff(void)
 147 {
 148         /* Stop the timer */
 149         del_timer(&timer);
 150         inb_p(wdt_stop);
 151         pr_info("Watchdog timer is now disabled...\n");
 152 }
 153
 154 static void wdt_keepalive(void)
 155 {
 156         /* user land ping */
 157         next_heartbeat = jiffies + (timeout * HZ);
 158 }
 159
 160 /*
 161  * /dev/watchdog handling
 162  */
 163
 164 static ssize_t fop_write(struct file *file, const char __user *buf,
 165                                                 size_t count, loff_t *ppos)
 166 {
 167         /* See if we got the magic character 'V' and reload the timer */
 168         if (count) {
 169                 if (!nowayout) {
 170                         size_t ofs;
 171
 172                         /* note: just in case someone wrote the
 173                            magic character five months ago... */
 174                         wdt_expect_close = 0;
 175
 176                         /* scan to see whether or not we got the
 177                            magic character */
 178                         for (ofs = 0; ofs != count; ofs++) {
 179                                 char c;
 180                                 if (get_user(c, buf + ofs))
 181                                         return -EFAULT;
 182                                 if (c == 'V')
 183                                         wdt_expect_close = 42;
 184                         }
 185                 }
 186
 187                 /* Well, anyhow someone wrote to us, we should
 188                    return that favour */
 189                 wdt_keepalive();
 190         }
 191         return count;
 192 }
 193
 194 static int fop_open(struct inode *inode, struct file *file)
 195 {
 196         /* Just in case we're already talking to someone... */
 197         if (test_and_set_bit(0, &wdt_is_open))
 198                 return -EBUSY;
 199
 200         if (nowayout)
 201                 __module_get(THIS_MODULE);
 202
 203         /* Good, fire up the show */
 204         wdt_startup();
 205         return stream_open(inode, file);
 206 }
 207
 208 static int fop_close(struct inode *inode, struct file *file)
 209 {
 210         if (wdt_expect_close == 42)
 211                 wdt_turnoff();
 212         else {
 213                 del_timer(&timer);
 214                 pr_crit("device file closed unexpectedly. Will not stop the WDT!\n");
 215         }
 216         clear_bit(0, &wdt_is_open);
 217         wdt_expect_close = 0;
 218         return 0;
 219 }
 220
 221 static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 222 {
 223         void __user *argp = (void __user *)arg;
 224         int __user *p = argp;
 225         static const struct watchdog_info ident = {
 226                 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
 227                                                         WDIOF_MAGICCLOSE,
 228                 .firmware_version = 1,
 229                 .identity = "SBC60xx",
 230         };
 231
 232         switch (cmd) {
 233         case WDIOC_GETSUPPORT:
 234                 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
 235         case WDIOC_GETSTATUS:
 236         case WDIOC_GETBOOTSTATUS:
 237                 return put_user(0, p);
 238         case WDIOC_SETOPTIONS:
 239         {
 240                 int new_options, retval = -EINVAL;
 241                 if (get_user(new_options, p))
 242                         return -EFAULT;
 243                 if (new_options & WDIOS_DISABLECARD) {
 244                         wdt_turnoff();
 245                         retval = 0;
 246                 }
 247                 if (new_options & WDIOS_ENABLECARD) {
 248                         wdt_startup();
 249                         retval = 0;
 250                 }
 251                 return retval;
 252         }
 253         case WDIOC_KEEPALIVE:
 254                 wdt_keepalive();
 255                 return 0;
 256         case WDIOC_SETTIMEOUT:
 257         {
 258                 int new_timeout;
 259                 if (get_user(new_timeout, p))
 260                         return -EFAULT;
 261                 /* arbitrary upper limit */
 262                 if (new_timeout < 1 || new_timeout > 3600)
 263                         return -EINVAL;
 264
 265                 timeout = new_timeout;
 266                 wdt_keepalive();
 267         }
 268                 fallthrough;
 269         case WDIOC_GETTIMEOUT:
 270                 return put_user(timeout, p);
 271         default:
 272                 return -ENOTTY;
 273         }
 274 }
 275
 276 static const struct file_operations wdt_fops = {
 277         .owner          = THIS_MODULE,
 278         .llseek         = no_llseek,
 279         .write          = fop_write,
 280         .open           = fop_open,
 281         .release        = fop_close,
 282         .unlocked_ioctl = fop_ioctl,
 283         .compat_ioctl   = compat_ptr_ioctl,
 284 };
 285
 286 static struct miscdevice wdt_miscdev = {
 287         .minor = WATCHDOG_MINOR,
 288         .name = "watchdog",
 289         .fops = &wdt_fops,
 290 };
 291
 292 /*
 293  *      Notifier for system down
 294  */
 295
 296 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 297         void *unused)
 298 {
 299         if (code == SYS_DOWN || code == SYS_HALT)
 300                 wdt_turnoff();
 301         return NOTIFY_DONE;
 302 }
 303
 304 /*
 305  *      The WDT needs to learn about soft shutdowns in order to
 306  *      turn the timebomb registers off.
 307  */
 308
 309 static struct notifier_block wdt_notifier = {
 310         .notifier_call = wdt_notify_sys,
 311 };
 312
 313 static void __exit sbc60xxwdt_unload(void)
 314 {
 315         wdt_turnoff();
 316
 317         /* Deregister */
 318         misc_deregister(&wdt_miscdev);
 319
 320         unregister_reboot_notifier(&wdt_notifier);
 321         if ((wdt_stop != 0x45) && (wdt_stop != wdt_start))
 322                 release_region(wdt_stop, 1);
 323         release_region(wdt_start, 1);
 324 }
 325
 326 static int __init sbc60xxwdt_init(void)
 327 {
 328         int rc = -EBUSY;
 329
 330         if (timeout < 1 || timeout > 3600) { /* arbitrary upper limit */
 331                 timeout = WATCHDOG_TIMEOUT;
 332                 pr_info("timeout value must be 1 <= x <= 3600, using %d\n",
 333                         timeout);
 334         }
 335
 336         if (!request_region(wdt_start, 1, "SBC 60XX WDT")) {
 337                 pr_err("I/O address 0x%04x already in use\n", wdt_start);
 338                 rc = -EIO;
 339                 goto err_out;
 340         }
 341
 342         /* We cannot reserve 0x45 - the kernel already has! */
 343         if (wdt_stop != 0x45 && wdt_stop != wdt_start) {
 344                 if (!request_region(wdt_stop, 1, "SBC 60XX WDT")) {
 345                         pr_err("I/O address 0x%04x already in use\n", wdt_stop);
 346                         rc = -EIO;
 347                         goto err_out_region1;
 348                 }
 349         }
 350
 351         rc = register_reboot_notifier(&wdt_notifier);
 352         if (rc) {
 353                 pr_err("cannot register reboot notifier (err=%d)\n", rc);
 354                 goto err_out_region2;
 355         }
 356
 357         rc = misc_register(&wdt_miscdev);
 358         if (rc) {
 359                 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
 360                        wdt_miscdev.minor, rc);
 361                 goto err_out_reboot;
 362         }
 363         pr_info("WDT driver for 60XX single board computer initialised. timeout=%d sec (nowayout=%d)\n",
 364                 timeout, nowayout);
 365
 366         return 0;
 367
 368 err_out_reboot:
 369         unregister_reboot_notifier(&wdt_notifier);
 370 err_out_region2:
 371         if (wdt_stop != 0x45 && wdt_stop != wdt_start)
 372                 release_region(wdt_stop, 1);
 373 err_out_region1:
 374         release_region(wdt_start, 1);
 375 err_out:
 376         return rc;
 377 }
 378
 379 module_init(sbc60xxwdt_init);
 380 module_exit(sbc60xxwdt_unload);
 381
 382 MODULE_AUTHOR("Jakob Oestergaard <jakob@unthought.net>");
 383 MODULE_DESCRIPTION("60xx Single Board Computer Watchdog Timer driver");
 384 MODULE_LICENSE("GPL");