drivers/watchdog/watchdog_dev.c

   1 /*
   2  *      watchdog_dev.c
   3  *
   4  *      (c) Copyright 2008-2011 Alan Cox <alan@lxorguk.ukuu.org.uk>,
   5  *                                              All Rights Reserved.
   6  *
   7  *      (c) Copyright 2008-2011 Wim Van Sebroeck <wim@iguana.be>.
   8  *
   9  *
  10  *      This source code is part of the generic code that can be used
  11  *      by all the watchdog timer drivers.
  12  *
  13  *      This part of the generic code takes care of the following
  14  *      misc device: /dev/watchdog.
  15  *
  16  *      Based on source code of the following authors:
  17  *        Matt Domsch <Matt_Domsch@dell.com>,
  18  *        Rob Radez <rob@osinvestor.com>,
  19  *        Rusty Lynch <rusty@linux.co.intel.com>
  20  *        Satyam Sharma <satyam@infradead.org>
  21  *        Randy Dunlap <randy.dunlap@oracle.com>
  22  *
  23  *      This program is free software; you can redistribute it and/or
  24  *      modify it under the terms of the GNU General Public License
  25  *      as published by the Free Software Foundation; either version
  26  *      2 of the License, or (at your option) any later version.
  27  *
  28  *      Neither Alan Cox, CymruNet Ltd., Wim Van Sebroeck nor Iguana vzw.
  29  *      admit liability nor provide warranty for any of this software.
  30  *      This material is provided "AS-IS" and at no charge.
  31  */
  32
  33 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  34
  35 #include <linux/cdev.h>         /* For character device */
  36 #include <linux/errno.h>        /* For the -ENODEV/... values */
  37 #include <linux/fs.h>           /* For file operations */
  38 #include <linux/init.h>         /* For __init/__exit/... */
  39 #include <linux/kernel.h>       /* For printk/panic/... */
  40 #include <linux/kref.h>         /* For data references */
  41 #include <linux/miscdevice.h>   /* For handling misc devices */
  42 #include <linux/module.h>       /* For module stuff/... */
  43 #include <linux/mutex.h>        /* For mutexes */
  44 #include <linux/slab.h>         /* For memory functions */
  45 #include <linux/types.h>        /* For standard types (like size_t) */
  46 #include <linux/watchdog.h>     /* For watchdog specific items */
  47 #include <linux/uaccess.h>      /* For copy_to_user/put_user/... */
  48
  49 #include "watchdog_core.h"
  50
  51 /*
  52  * struct watchdog_core_data - watchdog core internal data
  53  * @kref:       Reference count.
  54  * @cdev:       The watchdog's Character device.
  55  * @wdd:        Pointer to watchdog device.
  56  * @lock:       Lock for watchdog core.
  57  * @status:     Watchdog core internal status bits.
  58  */
  59 struct watchdog_core_data {
  60         struct kref kref;
  61         struct cdev cdev;
  62         struct watchdog_device *wdd;
  63         struct mutex lock;
  64         unsigned long status;           /* Internal status bits */
  65 #define _WDOG_DEV_OPEN          0       /* Opened ? */
  66 #define _WDOG_ALLOW_RELEASE     1       /* Did we receive the magic char ? */
  67 };
  68
  69 /* the dev_t structure to store the dynamically allocated watchdog devices */
  70 static dev_t watchdog_devt;
  71 /* Reference to watchdog device behind /dev/watchdog */
  72 static struct watchdog_core_data *old_wd_data;
  73
  74 /*
  75  *      watchdog_ping: ping the watchdog.
  76  *      @wdd: the watchdog device to ping
  77  *
  78  *      The caller must hold wd_data->lock.
  79  *
  80  *      If the watchdog has no own ping operation then it needs to be
  81  *      restarted via the start operation. This wrapper function does
  82  *      exactly that.
  83  *      We only ping when the watchdog device is running.
  84  */
  85
  86 static int watchdog_ping(struct watchdog_device *wdd)
  87 {
  88         int err;
  89
  90         if (!watchdog_active(wdd))
  91                 return 0;
  92
  93         if (wdd->ops->ping)
  94                 err = wdd->ops->ping(wdd);      /* ping the watchdog */
  95         else
  96                 err = wdd->ops->start(wdd);     /* restart watchdog */
  97
  98         return err;
  99 }
 100
 101 /*
 102  *      watchdog_start: wrapper to start the watchdog.
 103  *      @wdd: the watchdog device to start
 104  *
 105  *      The caller must hold wd_data->lock.
 106  *
 107  *      Start the watchdog if it is not active and mark it active.
 108  *      This function returns zero on success or a negative errno code for
 109  *      failure.
 110  */
 111
 112 static int watchdog_start(struct watchdog_device *wdd)
 113 {
 114         int err;
 115
 116         if (watchdog_active(wdd))
 117                 return 0;
 118
 119         err = wdd->ops->start(wdd);
 120         if (err == 0)
 121                 set_bit(WDOG_ACTIVE, &wdd->status);
 122
 123         return err;
 124 }
 125
 126 /*
 127  *      watchdog_stop: wrapper to stop the watchdog.
 128  *      @wdd: the watchdog device to stop
 129  *
 130  *      The caller must hold wd_data->lock.
 131  *
 132  *      Stop the watchdog if it is still active and unmark it active.
 133  *      This function returns zero on success or a negative errno code for
 134  *      failure.
 135  *      If the 'nowayout' feature was set, the watchdog cannot be stopped.
 136  */
 137
 138 static int watchdog_stop(struct watchdog_device *wdd)
 139 {
 140         int err;
 141
 142         if (!watchdog_active(wdd))
 143                 return 0;
 144
 145         if (test_bit(WDOG_NO_WAY_OUT, &wdd->status)) {
 146                 pr_info("watchdog%d: nowayout prevents watchdog being stopped!\n",
 147                         wdd->id);
 148                 return -EBUSY;
 149         }
 150
 151         err = wdd->ops->stop(wdd);
 152         if (err == 0)
 153                 clear_bit(WDOG_ACTIVE, &wdd->status);
 154
 155         return err;
 156 }
 157
 158 /*
 159  *      watchdog_get_status: wrapper to get the watchdog status
 160  *      @wdd: the watchdog device to get the status from
 161  *
 162  *      The caller must hold wd_data->lock.
 163  *
 164  *      Get the watchdog's status flags.
 165  */
 166
 167 static unsigned int watchdog_get_status(struct watchdog_device *wdd)
 168 {
 169         if (!wdd->ops->status)
 170                 return 0;
 171
 172         return wdd->ops->status(wdd);
 173 }
 174
 175 /*
 176  *      watchdog_set_timeout: set the watchdog timer timeout
 177  *      @wdd: the watchdog device to set the timeout for
 178  *      @timeout: timeout to set in seconds
 179  *
 180  *      The caller must hold wd_data->lock.
 181  */
 182
 183 static int watchdog_set_timeout(struct watchdog_device *wdd,
 184                                                         unsigned int timeout)
 185 {
 186         if (!wdd->ops->set_timeout || !(wdd->info->options & WDIOF_SETTIMEOUT))
 187                 return -EOPNOTSUPP;
 188
 189         if (watchdog_timeout_invalid(wdd, timeout))
 190                 return -EINVAL;
 191
 192         return wdd->ops->set_timeout(wdd, timeout);
 193 }
 194
 195 /*
 196  *      watchdog_get_timeleft: wrapper to get the time left before a reboot
 197  *      @wdd: the watchdog device to get the remaining time from
 198  *      @timeleft: the time that's left
 199  *
 200  *      The caller must hold wd_data->lock.
 201  *
 202  *      Get the time before a watchdog will reboot (if not pinged).
 203  */
 204
 205 static int watchdog_get_timeleft(struct watchdog_device *wdd,
 206                                                         unsigned int *timeleft)
 207 {
 208         *timeleft = 0;
 209
 210         if (!wdd->ops->get_timeleft)
 211                 return -EOPNOTSUPP;
 212
 213         *timeleft = wdd->ops->get_timeleft(wdd);
 214
 215         return 0;
 216 }
 217
 218 #ifdef CONFIG_WATCHDOG_SYSFS
 219 static ssize_t nowayout_show(struct device *dev, struct device_attribute *attr,
 220                                 char *buf)
 221 {
 222         struct watchdog_device *wdd = dev_get_drvdata(dev);
 223
 224         return sprintf(buf, "%d\n", !!test_bit(WDOG_NO_WAY_OUT, &wdd->status));
 225 }
 226 static DEVICE_ATTR_RO(nowayout);
 227
 228 static ssize_t status_show(struct device *dev, struct device_attribute *attr,
 229                                 char *buf)
 230 {
 231         struct watchdog_device *wdd = dev_get_drvdata(dev);
 232         struct watchdog_core_data *wd_data = wdd->wd_data;
 233         unsigned int status;
 234
 235         mutex_lock(&wd_data->lock);
 236         status = watchdog_get_status(wdd);
 237         mutex_unlock(&wd_data->lock);
 238
 239         return sprintf(buf, "%u\n", status);
 240 }
 241 static DEVICE_ATTR_RO(status);
 242
 243 static ssize_t bootstatus_show(struct device *dev,
 244                                 struct device_attribute *attr, char *buf)
 245 {
 246         struct watchdog_device *wdd = dev_get_drvdata(dev);
 247
 248         return sprintf(buf, "%u\n", wdd->bootstatus);
 249 }
 250 static DEVICE_ATTR_RO(bootstatus);
 251
 252 static ssize_t timeleft_show(struct device *dev, struct device_attribute *attr,
 253                                 char *buf)
 254 {
 255         struct watchdog_device *wdd = dev_get_drvdata(dev);
 256         struct watchdog_core_data *wd_data = wdd->wd_data;
 257         ssize_t status;
 258         unsigned int val;
 259
 260         mutex_lock(&wd_data->lock);
 261         status = watchdog_get_timeleft(wdd, &val);
 262         mutex_unlock(&wd_data->lock);
 263         if (!status)
 264                 status = sprintf(buf, "%u\n", val);
 265
 266         return status;
 267 }
 268 static DEVICE_ATTR_RO(timeleft);
 269
 270 static ssize_t timeout_show(struct device *dev, struct device_attribute *attr,
 271                                 char *buf)
 272 {
 273         struct watchdog_device *wdd = dev_get_drvdata(dev);
 274
 275         return sprintf(buf, "%u\n", wdd->timeout);
 276 }
 277 static DEVICE_ATTR_RO(timeout);
 278
 279 static ssize_t identity_show(struct device *dev, struct device_attribute *attr,
 280                                 char *buf)
 281 {
 282         struct watchdog_device *wdd = dev_get_drvdata(dev);
 283
 284         return sprintf(buf, "%s\n", wdd->info->identity);
 285 }
 286 static DEVICE_ATTR_RO(identity);
 287
 288 static ssize_t state_show(struct device *dev, struct device_attribute *attr,
 289                                 char *buf)
 290 {
 291         struct watchdog_device *wdd = dev_get_drvdata(dev);
 292
 293         if (watchdog_active(wdd))
 294                 return sprintf(buf, "active\n");
 295
 296         return sprintf(buf, "inactive\n");
 297 }
 298 static DEVICE_ATTR_RO(state);
 299
 300 static umode_t wdt_is_visible(struct kobject *kobj, struct attribute *attr,
 301                                 int n)
 302 {
 303         struct device *dev = container_of(kobj, struct device, kobj);
 304         struct watchdog_device *wdd = dev_get_drvdata(dev);
 305         umode_t mode = attr->mode;
 306
 307         if (attr == &dev_attr_status.attr && !wdd->ops->status)
 308                 mode = 0;
 309         else if (attr == &dev_attr_timeleft.attr && !wdd->ops->get_timeleft)
 310                 mode = 0;
 311
 312         return mode;
 313 }
 314 static struct attribute *wdt_attrs[] = {
 315         &dev_attr_state.attr,
 316         &dev_attr_identity.attr,
 317         &dev_attr_timeout.attr,
 318         &dev_attr_timeleft.attr,
 319         &dev_attr_bootstatus.attr,
 320         &dev_attr_status.attr,
 321         &dev_attr_nowayout.attr,
 322         NULL,
 323 };
 324
 325 static const struct attribute_group wdt_group = {
 326         .attrs = wdt_attrs,
 327         .is_visible = wdt_is_visible,
 328 };
 329 __ATTRIBUTE_GROUPS(wdt);
 330 #else
 331 #define wdt_groups      NULL
 332 #endif
 333
 334 /*
 335  *      watchdog_ioctl_op: call the watchdog drivers ioctl op if defined
 336  *      @wdd: the watchdog device to do the ioctl on
 337  *      @cmd: watchdog command
 338  *      @arg: argument pointer
 339  *
 340  *      The caller must hold wd_data->lock.
 341  */
 342
 343 static int watchdog_ioctl_op(struct watchdog_device *wdd, unsigned int cmd,
 344                                                         unsigned long arg)
 345 {
 346         if (!wdd->ops->ioctl)
 347                 return -ENOIOCTLCMD;
 348
 349         return wdd->ops->ioctl(wdd, cmd, arg);
 350 }
 351
 352 /*
 353  *      watchdog_write: writes to the watchdog.
 354  *      @file: file from VFS
 355  *      @data: user address of data
 356  *      @len: length of data
 357  *      @ppos: pointer to the file offset
 358  *
 359  *      A write to a watchdog device is defined as a keepalive ping.
 360  *      Writing the magic 'V' sequence allows the next close to turn
 361  *      off the watchdog (if 'nowayout' is not set).
 362  */
 363
 364 static ssize_t watchdog_write(struct file *file, const char __user *data,
 365                                                 size_t len, loff_t *ppos)
 366 {
 367         struct watchdog_core_data *wd_data = file->private_data;
 368         struct watchdog_device *wdd;
 369         int err;
 370         size_t i;
 371         char c;
 372
 373         if (len == 0)
 374                 return 0;
 375
 376         /*
 377          * Note: just in case someone wrote the magic character
 378          * five months ago...
 379          */
 380         clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);
 381
 382         /* scan to see whether or not we got the magic character */
 383         for (i = 0; i != len; i++) {
 384                 if (get_user(c, data + i))
 385                         return -EFAULT;
 386                 if (c == 'V')
 387                         set_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);
 388         }
 389
 390         /* someone wrote to us, so we send the watchdog a keepalive ping */
 391
 392         err = -ENODEV;
 393         mutex_lock(&wd_data->lock);
 394         wdd = wd_data->wdd;
 395         if (wdd)
 396                 err = watchdog_ping(wdd);
 397         mutex_unlock(&wd_data->lock);
 398
 399         if (err < 0)
 400                 return err;
 401
 402         return len;
 403 }
 404
 405 /*
 406  *      watchdog_ioctl: handle the different ioctl's for the watchdog device.
 407  *      @file: file handle to the device
 408  *      @cmd: watchdog command
 409  *      @arg: argument pointer
 410  *
 411  *      The watchdog API defines a common set of functions for all watchdogs
 412  *      according to their available features.
 413  */
 414
 415 static long watchdog_ioctl(struct file *file, unsigned int cmd,
 416                                                         unsigned long arg)
 417 {
 418         struct watchdog_core_data *wd_data = file->private_data;
 419         void __user *argp = (void __user *)arg;
 420         struct watchdog_device *wdd;
 421         int __user *p = argp;
 422         unsigned int val;
 423         int err;
 424
 425         mutex_lock(&wd_data->lock);
 426
 427         wdd = wd_data->wdd;
 428         if (!wdd) {
 429                 err = -ENODEV;
 430                 goto out_ioctl;
 431         }
 432
 433         err = watchdog_ioctl_op(wdd, cmd, arg);
 434         if (err != -ENOIOCTLCMD)
 435                 goto out_ioctl;
 436
 437         switch (cmd) {
 438         case WDIOC_GETSUPPORT:
 439                 err = copy_to_user(argp, wdd->info,
 440                         sizeof(struct watchdog_info)) ? -EFAULT : 0;
 441                 break;
 442         case WDIOC_GETSTATUS:
 443                 val = watchdog_get_status(wdd);
 444                 err = put_user(val, p);
 445                 break;
 446         case WDIOC_GETBOOTSTATUS:
 447                 err = put_user(wdd->bootstatus, p);
 448                 break;
 449         case WDIOC_SETOPTIONS:
 450                 if (get_user(val, p)) {
 451                         err = -EFAULT;
 452                         break;
 453                 }
 454                 if (val & WDIOS_DISABLECARD) {
 455                         err = watchdog_stop(wdd);
 456                         if (err < 0)
 457                                 break;
 458                 }
 459                 if (val & WDIOS_ENABLECARD)
 460                         err = watchdog_start(wdd);
 461                 break;
 462         case WDIOC_KEEPALIVE:
 463                 if (!(wdd->info->options & WDIOF_KEEPALIVEPING)) {
 464                         err = -EOPNOTSUPP;
 465                         break;
 466                 }
 467                 err = watchdog_ping(wdd);
 468                 break;
 469         case WDIOC_SETTIMEOUT:
 470                 if (get_user(val, p)) {
 471                         err = -EFAULT;
 472                         break;
 473                 }
 474                 err = watchdog_set_timeout(wdd, val);
 475                 if (err < 0)
 476                         break;
 477                 /* If the watchdog is active then we send a keepalive ping
 478                  * to make sure that the watchdog keep's running (and if
 479                  * possible that it takes the new timeout) */
 480                 err = watchdog_ping(wdd);
 481                 if (err < 0)
 482                         break;
 483                 /* Fall */
 484         case WDIOC_GETTIMEOUT:
 485                 /* timeout == 0 means that we don't know the timeout */
 486                 if (wdd->timeout == 0) {
 487                         err = -EOPNOTSUPP;
 488                         break;
 489                 }
 490                 err = put_user(wdd->timeout, p);
 491                 break;
 492         case WDIOC_GETTIMELEFT:
 493                 err = watchdog_get_timeleft(wdd, &val);
 494                 if (err < 0)
 495                         break;
 496                 err = put_user(val, p);
 497                 break;
 498         default:
 499                 err = -ENOTTY;
 500                 break;
 501         }
 502
 503 out_ioctl:
 504         mutex_unlock(&wd_data->lock);
 505         return err;
 506 }
 507
 508 /*
 509  *      watchdog_open: open the /dev/watchdog* devices.
 510  *      @inode: inode of device
 511  *      @file: file handle to device
 512  *
 513  *      When the /dev/watchdog* device gets opened, we start the watchdog.
 514  *      Watch out: the /dev/watchdog device is single open, so we make sure
 515  *      it can only be opened once.
 516  */
 517
 518 static int watchdog_open(struct inode *inode, struct file *file)
 519 {
 520         struct watchdog_core_data *wd_data;
 521         struct watchdog_device *wdd;
 522         int err;
 523
 524         /* Get the corresponding watchdog device */
 525         if (imajor(inode) == MISC_MAJOR)
 526                 wd_data = old_wd_data;
 527         else
 528                 wd_data = container_of(inode->i_cdev, struct watchdog_core_data,
 529                                        cdev);
 530
 531         /* the watchdog is single open! */
 532         if (test_and_set_bit(_WDOG_DEV_OPEN, &wd_data->status))
 533                 return -EBUSY;
 534
 535         wdd = wd_data->wdd;
 536
 537         /*
 538          * If the /dev/watchdog device is open, we don't want the module
 539          * to be unloaded.
 540          */
 541         if (!try_module_get(wdd->ops->owner)) {
 542                 err = -EBUSY;
 543                 goto out_clear;
 544         }
 545
 546         err = watchdog_start(wdd);
 547         if (err < 0)
 548                 goto out_mod;
 549
 550         file->private_data = wd_data;
 551
 552         kref_get(&wd_data->kref);
 553
 554         /* dev/watchdog is a virtual (and thus non-seekable) filesystem */
 555         return nonseekable_open(inode, file);
 556
 557 out_mod:
 558         module_put(wd_data->wdd->ops->owner);
 559 out_clear:
 560         clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
 561         return err;
 562 }
 563
 564 static void watchdog_core_data_release(struct kref *kref)
 565 {
 566         struct watchdog_core_data *wd_data;
 567
 568         wd_data = container_of(kref, struct watchdog_core_data, kref);
 569
 570         kfree(wd_data);
 571 }
 572
 573 /*
 574  *      watchdog_release: release the watchdog device.
 575  *      @inode: inode of device
 576  *      @file: file handle to device
 577  *
 578  *      This is the code for when /dev/watchdog gets closed. We will only
 579  *      stop the watchdog when we have received the magic char (and nowayout
 580  *      was not set), else the watchdog will keep running.
 581  */
 582
 583 static int watchdog_release(struct inode *inode, struct file *file)
 584 {
 585         struct watchdog_core_data *wd_data = file->private_data;
 586         struct watchdog_device *wdd;
 587         int err = -EBUSY;
 588
 589         mutex_lock(&wd_data->lock);
 590
 591         wdd = wd_data->wdd;
 592         if (!wdd)
 593                 goto done;
 594
 595         /*
 596          * We only stop the watchdog if we received the magic character
 597          * or if WDIOF_MAGICCLOSE is not set. If nowayout was set then
 598          * watchdog_stop will fail.
 599          */
 600         if (!test_bit(WDOG_ACTIVE, &wdd->status))
 601                 err = 0;
 602         else if (test_and_clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status) ||
 603                  !(wdd->info->options & WDIOF_MAGICCLOSE))
 604                 err = watchdog_stop(wdd);
 605
 606         /* If the watchdog was not stopped, send a keepalive ping */
 607         if (err < 0) {
 608                 pr_crit("watchdog%d: watchdog did not stop!\n", wdd->id);
 609                 watchdog_ping(wdd);
 610         }
 611
 612         /* make sure that /dev/watchdog can be re-opened */
 613         clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
 614
 615 done:
 616         mutex_unlock(&wd_data->lock);
 617         /* Allow the owner module to be unloaded again */
 618         module_put(wd_data->cdev.owner);
 619         kref_put(&wd_data->kref, watchdog_core_data_release);
 620         return 0;
 621 }
 622
 623 static const struct file_operations watchdog_fops = {
 624         .owner          = THIS_MODULE,
 625         .write          = watchdog_write,
 626         .unlocked_ioctl = watchdog_ioctl,
 627         .open           = watchdog_open,
 628         .release        = watchdog_release,
 629 };
 630
 631 static struct miscdevice watchdog_miscdev = {
 632         .minor          = WATCHDOG_MINOR,
 633         .name           = "watchdog",
 634         .fops           = &watchdog_fops,
 635 };
 636
 637 /*
 638  *      watchdog_cdev_register: register watchdog character device
 639  *      @wdd: watchdog device
 640  *      @devno: character device number
 641  *
 642  *      Register a watchdog character device including handling the legacy
 643  *      /dev/watchdog node. /dev/watchdog is actually a miscdevice and
 644  *      thus we set it up like that.
 645  */
 646
 647 static int watchdog_cdev_register(struct watchdog_device *wdd, dev_t devno)
 648 {
 649         struct watchdog_core_data *wd_data;
 650         int err;
 651
 652         wd_data = kzalloc(sizeof(struct watchdog_core_data), GFP_KERNEL);
 653         if (!wd_data)
 654                 return -ENOMEM;
 655         kref_init(&wd_data->kref);
 656         mutex_init(&wd_data->lock);
 657
 658         wd_data->wdd = wdd;
 659         wdd->wd_data = wd_data;
 660
 661         if (wdd->id == 0) {
 662                 old_wd_data = wd_data;
 663                 watchdog_miscdev.parent = wdd->parent;
 664                 err = misc_register(&watchdog_miscdev);
 665                 if (err != 0) {
 666                         pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n",
 667                                 wdd->info->identity, WATCHDOG_MINOR, err);
 668                         if (err == -EBUSY)
 669                                 pr_err("%s: a legacy watchdog module is probably present.\n",
 670                                         wdd->info->identity);
 671                         old_wd_data = NULL;
 672                         kfree(wd_data);
 673                         return err;
 674                 }
 675         }
 676
 677         /* Fill in the data structures */
 678         cdev_init(&wd_data->cdev, &watchdog_fops);
 679         wd_data->cdev.owner = wdd->ops->owner;
 680
 681         /* Add the device */
 682         err = cdev_add(&wd_data->cdev, devno, 1);
 683         if (err) {
 684                 pr_err("watchdog%d unable to add device %d:%d\n",
 685                         wdd->id,  MAJOR(watchdog_devt), wdd->id);
 686                 if (wdd->id == 0) {
 687                         misc_deregister(&watchdog_miscdev);
 688                         old_wd_data = NULL;
 689                         kref_put(&wd_data->kref, watchdog_core_data_release);
 690                 }
 691         }
 692         return err;
 693 }
 694
 695 /*
 696  *      watchdog_cdev_unregister: unregister watchdog character device
 697  *      @watchdog: watchdog device
 698  *
 699  *      Unregister watchdog character device and if needed the legacy
 700  *      /dev/watchdog device.
 701  */
 702
 703 static void watchdog_cdev_unregister(struct watchdog_device *wdd)
 704 {
 705         struct watchdog_core_data *wd_data = wdd->wd_data;
 706
 707         cdev_del(&wd_data->cdev);
 708         if (wdd->id == 0) {
 709                 misc_deregister(&watchdog_miscdev);
 710                 old_wd_data = NULL;
 711         }
 712
 713         mutex_lock(&wd_data->lock);
 714         wd_data->wdd = NULL;
 715         wdd->wd_data = NULL;
 716         mutex_unlock(&wd_data->lock);
 717
 718         kref_put(&wd_data->kref, watchdog_core_data_release);
 719 }
 720
 721 static struct class watchdog_class = {
 722         .name =         "watchdog",
 723         .owner =        THIS_MODULE,
 724         .dev_groups =   wdt_groups,
 725 };
 726
 727 /*
 728  *      watchdog_dev_register: register a watchdog device
 729  *      @wdd: watchdog device
 730  *
 731  *      Register a watchdog device including handling the legacy
 732  *      /dev/watchdog node. /dev/watchdog is actually a miscdevice and
 733  *      thus we set it up like that.
 734  */
 735
 736 int watchdog_dev_register(struct watchdog_device *wdd)
 737 {
 738         struct device *dev;
 739         dev_t devno;
 740         int ret;
 741
 742         devno = MKDEV(MAJOR(watchdog_devt), wdd->id);
 743
 744         ret = watchdog_cdev_register(wdd, devno);
 745         if (ret)
 746                 return ret;
 747
 748         dev = device_create_with_groups(&watchdog_class, wdd->parent,
 749                                         devno, wdd, wdd->groups,
 750                                         "watchdog%d", wdd->id);
 751         if (IS_ERR(dev)) {
 752                 watchdog_cdev_unregister(wdd);
 753                 return PTR_ERR(dev);
 754         }
 755
 756         return ret;
 757 }
 758
 759 /*
 760  *      watchdog_dev_unregister: unregister a watchdog device
 761  *      @watchdog: watchdog device
 762  *
 763  *      Unregister watchdog device and if needed the legacy
 764  *      /dev/watchdog device.
 765  */
 766
 767 void watchdog_dev_unregister(struct watchdog_device *wdd)
 768 {
 769         device_destroy(&watchdog_class, wdd->wd_data->cdev.dev);
 770         watchdog_cdev_unregister(wdd);
 771 }
 772
 773 /*
 774  *      watchdog_dev_init: init dev part of watchdog core
 775  *
 776  *      Allocate a range of chardev nodes to use for watchdog devices
 777  */
 778
 779 int __init watchdog_dev_init(void)
 780 {
 781         int err;
 782
 783         err = class_register(&watchdog_class);
 784         if (err < 0) {
 785                 pr_err("couldn't register class\n");
 786                 return err;
 787         }
 788
 789         err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog");
 790         if (err < 0) {
 791                 pr_err("watchdog: unable to allocate char dev region\n");
 792                 class_unregister(&watchdog_class);
 793                 return err;
 794         }
 795
 796         return 0;
 797 }
 798
 799 /*
 800  *      watchdog_dev_exit: exit dev part of watchdog core
 801  *
 802  *      Release the range of chardev nodes used for watchdog devices
 803  */
 804
 805 void __exit watchdog_dev_exit(void)
 806 {
 807         unregister_chrdev_region(watchdog_devt, MAX_DOGS);
 808         class_unregister(&watchdog_class);
 809 }