drivers/watchdog/mei_wdt.c

   1 /*
   2  * Intel Management Engine Interface (Intel MEI) Linux driver
   3  * Copyright (c) 2015, Intel Corporation.
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms and conditions of the GNU General Public License,
   7  * version 2, as published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
  12  * more details.
  13  */
  14
  15 #include <linux/module.h>
  16 #include <linux/slab.h>
  17 #include <linux/interrupt.h>
  18 #include <linux/debugfs.h>
  19 #include <linux/completion.h>
  20 #include <linux/watchdog.h>
  21
  22 #include <linux/uuid.h>
  23 #include <linux/mei_cl_bus.h>
  24
  25 /*
  26  * iAMT Watchdog Device
  27  */
  28 #define INTEL_AMT_WATCHDOG_ID "iamt_wdt"
  29
  30 #define MEI_WDT_DEFAULT_TIMEOUT   120  /* seconds */
  31 #define MEI_WDT_MIN_TIMEOUT       120  /* seconds */
  32 #define MEI_WDT_MAX_TIMEOUT     65535  /* seconds */
  33
  34 /* Commands */
  35 #define MEI_MANAGEMENT_CONTROL 0x02
  36
  37 /* MEI Management Control version number */
  38 #define MEI_MC_VERSION_NUMBER  0x10
  39
  40 /* Sub Commands */
  41 #define MEI_MC_START_WD_TIMER_REQ  0x13
  42 #define MEI_MC_START_WD_TIMER_RES  0x83
  43 #define   MEI_WDT_STATUS_SUCCESS 0
  44 #define   MEI_WDT_WDSTATE_NOT_REQUIRED 0x1
  45 #define MEI_MC_STOP_WD_TIMER_REQ   0x14
  46
  47 /**
  48  * enum mei_wdt_state - internal watchdog state
  49  *
  50  * @MEI_WDT_PROBE: wd in probing stage
  51  * @MEI_WDT_IDLE: wd is idle and not opened
  52  * @MEI_WDT_START: wd was opened, start was called
  53  * @MEI_WDT_RUNNING: wd is expecting keep alive pings
  54  * @MEI_WDT_STOPPING: wd is stopping and will move to IDLE
  55  * @MEI_WDT_NOT_REQUIRED: wd device is not required
  56  */
  57 enum mei_wdt_state {
  58         MEI_WDT_PROBE,
  59         MEI_WDT_IDLE,
  60         MEI_WDT_START,
  61         MEI_WDT_RUNNING,
  62         MEI_WDT_STOPPING,
  63         MEI_WDT_NOT_REQUIRED,
  64 };
  65
  66 static const char *mei_wdt_state_str(enum mei_wdt_state state)
  67 {
  68         switch (state) {
  69         case MEI_WDT_PROBE:
  70                 return "PROBE";
  71         case MEI_WDT_IDLE:
  72                 return "IDLE";
  73         case MEI_WDT_START:
  74                 return "START";
  75         case MEI_WDT_RUNNING:
  76                 return "RUNNING";
  77         case MEI_WDT_STOPPING:
  78                 return "STOPPING";
  79         case MEI_WDT_NOT_REQUIRED:
  80                 return "NOT_REQUIRED";
  81         default:
  82                 return "unknown";
  83         }
  84 }
  85
  86 /**
  87  * struct mei_wdt - mei watchdog driver
  88  * @wdd: watchdog device
  89  *
  90  * @cldev: mei watchdog client device
  91  * @state: watchdog internal state
  92  * @resp_required: ping required response
  93  * @response: ping response completion
  94  * @unregister: unregister worker
  95  * @reg_lock: watchdog device registration lock
  96  * @timeout: watchdog current timeout
  97  *
  98  * @dbgfs_dir: debugfs dir entry
  99  */
 100 struct mei_wdt {
 101         struct watchdog_device wdd;
 102
 103         struct mei_cl_device *cldev;
 104         enum mei_wdt_state state;
 105         bool resp_required;
 106         struct completion response;
 107         struct work_struct unregister;
 108         struct mutex reg_lock;
 109         u16 timeout;
 110
 111 #if IS_ENABLED(CONFIG_DEBUG_FS)
 112         struct dentry *dbgfs_dir;
 113 #endif /* CONFIG_DEBUG_FS */
 114 };
 115
 116 /*
 117  * struct mei_mc_hdr - Management Control Command Header
 118  *
 119  * @command: Management Control (0x2)
 120  * @bytecount: Number of bytes in the message beyond this byte
 121  * @subcommand: Management Control Subcommand
 122  * @versionnumber: Management Control Version (0x10)
 123  */
 124 struct mei_mc_hdr {
 125         u8 command;
 126         u8 bytecount;
 127         u8 subcommand;
 128         u8 versionnumber;
 129 };
 130
 131 /**
 132  * struct mei_wdt_start_request watchdog start/ping
 133  *
 134  * @hdr: Management Control Command Header
 135  * @timeout: timeout value
 136  * @reserved: reserved (legacy)
 137  */
 138 struct mei_wdt_start_request {
 139         struct mei_mc_hdr hdr;
 140         u16 timeout;
 141         u8 reserved[17];
 142 } __packed;
 143
 144 /**
 145  * struct mei_wdt_start_response watchdog start/ping response
 146  *
 147  * @hdr: Management Control Command Header
 148  * @status: operation status
 149  * @wdstate: watchdog status bit mask
 150  */
 151 struct mei_wdt_start_response {
 152         struct mei_mc_hdr hdr;
 153         u8 status;
 154         u8 wdstate;
 155 } __packed;
 156
 157 /**
 158  * struct mei_wdt_stop_request - watchdog stop
 159  *
 160  * @hdr: Management Control Command Header
 161  */
 162 struct mei_wdt_stop_request {
 163         struct mei_mc_hdr hdr;
 164 } __packed;
 165
 166 /**
 167  * mei_wdt_ping - send wd start/ping command
 168  *
 169  * @wdt: mei watchdog device
 170  *
 171  * Return: 0 on success,
 172  *         negative errno code on failure
 173  */
 174 static int mei_wdt_ping(struct mei_wdt *wdt)
 175 {
 176         struct mei_wdt_start_request req;
 177         const size_t req_len = sizeof(req);
 178         int ret;
 179
 180         memset(&req, 0, req_len);
 181         req.hdr.command = MEI_MANAGEMENT_CONTROL;
 182         req.hdr.bytecount = req_len - offsetof(struct mei_mc_hdr, subcommand);
 183         req.hdr.subcommand = MEI_MC_START_WD_TIMER_REQ;
 184         req.hdr.versionnumber = MEI_MC_VERSION_NUMBER;
 185         req.timeout = wdt->timeout;
 186
 187         ret = mei_cldev_send(wdt->cldev, (u8 *)&req, req_len);
 188         if (ret < 0)
 189                 return ret;
 190
 191         return 0;
 192 }
 193
 194 /**
 195  * mei_wdt_stop - send wd stop command
 196  *
 197  * @wdt: mei watchdog device
 198  *
 199  * Return: 0 on success,
 200  *         negative errno code on failure
 201  */
 202 static int mei_wdt_stop(struct mei_wdt *wdt)
 203 {
 204         struct mei_wdt_stop_request req;
 205         const size_t req_len = sizeof(req);
 206         int ret;
 207
 208         memset(&req, 0, req_len);
 209         req.hdr.command = MEI_MANAGEMENT_CONTROL;
 210         req.hdr.bytecount = req_len - offsetof(struct mei_mc_hdr, subcommand);
 211         req.hdr.subcommand = MEI_MC_STOP_WD_TIMER_REQ;
 212         req.hdr.versionnumber = MEI_MC_VERSION_NUMBER;
 213
 214         ret = mei_cldev_send(wdt->cldev, (u8 *)&req, req_len);
 215         if (ret < 0)
 216                 return ret;
 217
 218         return 0;
 219 }
 220
 221 /**
 222  * mei_wdt_ops_start - wd start command from the watchdog core.
 223  *
 224  * @wdd: watchdog device
 225  *
 226  * Return: 0 on success or -ENODEV;
 227  */
 228 static int mei_wdt_ops_start(struct watchdog_device *wdd)
 229 {
 230         struct mei_wdt *wdt = watchdog_get_drvdata(wdd);
 231
 232         wdt->state = MEI_WDT_START;
 233         wdd->timeout = wdt->timeout;
 234         return 0;
 235 }
 236
 237 /**
 238  * mei_wdt_ops_stop - wd stop command from the watchdog core.
 239  *
 240  * @wdd: watchdog device
 241  *
 242  * Return: 0 if success, negative errno code for failure
 243  */
 244 static int mei_wdt_ops_stop(struct watchdog_device *wdd)
 245 {
 246         struct mei_wdt *wdt = watchdog_get_drvdata(wdd);
 247         int ret;
 248
 249         if (wdt->state != MEI_WDT_RUNNING)
 250                 return 0;
 251
 252         wdt->state = MEI_WDT_STOPPING;
 253
 254         ret = mei_wdt_stop(wdt);
 255         if (ret)
 256                 return ret;
 257
 258         wdt->state = MEI_WDT_IDLE;
 259
 260         return 0;
 261 }
 262
 263 /**
 264  * mei_wdt_ops_ping - wd ping command from the watchdog core.
 265  *
 266  * @wdd: watchdog device
 267  *
 268  * Return: 0 if success, negative errno code on failure
 269  */
 270 static int mei_wdt_ops_ping(struct watchdog_device *wdd)
 271 {
 272         struct mei_wdt *wdt = watchdog_get_drvdata(wdd);
 273         int ret;
 274
 275         if (wdt->state != MEI_WDT_START && wdt->state != MEI_WDT_RUNNING)
 276                 return 0;
 277
 278         if (wdt->resp_required)
 279                 init_completion(&wdt->response);
 280
 281         wdt->state = MEI_WDT_RUNNING;
 282         ret = mei_wdt_ping(wdt);
 283         if (ret)
 284                 return ret;
 285
 286         if (wdt->resp_required)
 287                 ret = wait_for_completion_killable(&wdt->response);
 288
 289         return ret;
 290 }
 291
 292 /**
 293  * mei_wdt_ops_set_timeout - wd set timeout command from the watchdog core.
 294  *
 295  * @wdd: watchdog device
 296  * @timeout: timeout value to set
 297  *
 298  * Return: 0 if success, negative errno code for failure
 299  */
 300 static int mei_wdt_ops_set_timeout(struct watchdog_device *wdd,
 301                                    unsigned int timeout)
 302 {
 303
 304         struct mei_wdt *wdt = watchdog_get_drvdata(wdd);
 305
 306         /* valid value is already checked by the caller */
 307         wdt->timeout = timeout;
 308         wdd->timeout = timeout;
 309
 310         return 0;
 311 }
 312
 313 static const struct watchdog_ops wd_ops = {
 314         .owner       = THIS_MODULE,
 315         .start       = mei_wdt_ops_start,
 316         .stop        = mei_wdt_ops_stop,
 317         .ping        = mei_wdt_ops_ping,
 318         .set_timeout = mei_wdt_ops_set_timeout,
 319 };
 320
 321 /* not const as the firmware_version field need to be retrieved */
 322 static struct watchdog_info wd_info = {
 323         .identity = INTEL_AMT_WATCHDOG_ID,
 324         .options  = WDIOF_KEEPALIVEPING |
 325                     WDIOF_SETTIMEOUT |
 326                     WDIOF_ALARMONLY,
 327 };
 328
 329 /**
 330  * __mei_wdt_is_registered - check if wdt is registered
 331  *
 332  * @wdt: mei watchdog device
 333  *
 334  * Return: true if the wdt is registered with the watchdog subsystem
 335  * Locking: should be called under wdt->reg_lock
 336  */
 337 static inline bool __mei_wdt_is_registered(struct mei_wdt *wdt)
 338 {
 339         return !!watchdog_get_drvdata(&wdt->wdd);
 340 }
 341
 342 /**
 343  * mei_wdt_unregister - unregister from the watchdog subsystem
 344  *
 345  * @wdt: mei watchdog device
 346  */
 347 static void mei_wdt_unregister(struct mei_wdt *wdt)
 348 {
 349         mutex_lock(&wdt->reg_lock);
 350
 351         if (__mei_wdt_is_registered(wdt)) {
 352                 watchdog_unregister_device(&wdt->wdd);
 353                 watchdog_set_drvdata(&wdt->wdd, NULL);
 354                 memset(&wdt->wdd, 0, sizeof(wdt->wdd));
 355         }
 356
 357         mutex_unlock(&wdt->reg_lock);
 358 }
 359
 360 /**
 361  * mei_wdt_register - register with the watchdog subsystem
 362  *
 363  * @wdt: mei watchdog device
 364  *
 365  * Return: 0 if success, negative errno code for failure
 366  */
 367 static int mei_wdt_register(struct mei_wdt *wdt)
 368 {
 369         struct device *dev;
 370         int ret;
 371
 372         if (!wdt || !wdt->cldev)
 373                 return -EINVAL;
 374
 375         dev = &wdt->cldev->dev;
 376
 377         mutex_lock(&wdt->reg_lock);
 378
 379         if (__mei_wdt_is_registered(wdt)) {
 380                 ret = 0;
 381                 goto out;
 382         }
 383
 384         wdt->wdd.info = &wd_info;
 385         wdt->wdd.ops = &wd_ops;
 386         wdt->wdd.parent = dev;
 387         wdt->wdd.timeout = MEI_WDT_DEFAULT_TIMEOUT;
 388         wdt->wdd.min_timeout = MEI_WDT_MIN_TIMEOUT;
 389         wdt->wdd.max_timeout = MEI_WDT_MAX_TIMEOUT;
 390
 391         watchdog_set_drvdata(&wdt->wdd, wdt);
 392         watchdog_stop_on_reboot(&wdt->wdd);
 393
 394         ret = watchdog_register_device(&wdt->wdd);
 395         if (ret) {
 396                 dev_err(dev, "unable to register watchdog device = %d.\n", ret);
 397                 watchdog_set_drvdata(&wdt->wdd, NULL);
 398         }
 399
 400         wdt->state = MEI_WDT_IDLE;
 401
 402 out:
 403         mutex_unlock(&wdt->reg_lock);
 404         return ret;
 405 }
 406
 407 static void mei_wdt_unregister_work(struct work_struct *work)
 408 {
 409         struct mei_wdt *wdt = container_of(work, struct mei_wdt, unregister);
 410
 411         mei_wdt_unregister(wdt);
 412 }
 413
 414 /**
 415  * mei_wdt_rx - callback for data receive
 416  *
 417  * @cldev: bus device
 418  */
 419 static void mei_wdt_rx(struct mei_cl_device *cldev)
 420 {
 421         struct mei_wdt *wdt = mei_cldev_get_drvdata(cldev);
 422         struct mei_wdt_start_response res;
 423         const size_t res_len = sizeof(res);
 424         int ret;
 425
 426         ret = mei_cldev_recv(wdt->cldev, (u8 *)&res, res_len);
 427         if (ret < 0) {
 428                 dev_err(&cldev->dev, "failure in recv %d\n", ret);
 429                 return;
 430         }
 431
 432         /* Empty response can be sent on stop */
 433         if (ret == 0)
 434                 return;
 435
 436         if (ret < sizeof(struct mei_mc_hdr)) {
 437                 dev_err(&cldev->dev, "recv small data %d\n", ret);
 438                 return;
 439         }
 440
 441         if (res.hdr.command != MEI_MANAGEMENT_CONTROL ||
 442             res.hdr.versionnumber != MEI_MC_VERSION_NUMBER) {
 443                 dev_err(&cldev->dev, "wrong command received\n");
 444                 return;
 445         }
 446
 447         if (res.hdr.subcommand != MEI_MC_START_WD_TIMER_RES) {
 448                 dev_warn(&cldev->dev, "unsupported command %d :%s[%d]\n",
 449                          res.hdr.subcommand,
 450                          mei_wdt_state_str(wdt->state),
 451                          wdt->state);
 452                 return;
 453         }
 454
 455         /* Run the unregistration in a worker as this can be
 456          * run only after ping completion, otherwise the flow will
 457          * deadlock on watchdog core mutex.
 458          */
 459         if (wdt->state == MEI_WDT_RUNNING) {
 460                 if (res.wdstate & MEI_WDT_WDSTATE_NOT_REQUIRED) {
 461                         wdt->state = MEI_WDT_NOT_REQUIRED;
 462                         schedule_work(&wdt->unregister);
 463                 }
 464                 goto out;
 465         }
 466
 467         if (wdt->state == MEI_WDT_PROBE) {
 468                 if (res.wdstate & MEI_WDT_WDSTATE_NOT_REQUIRED) {
 469                         wdt->state = MEI_WDT_NOT_REQUIRED;
 470                 } else {
 471                         /* stop the watchdog and register watchdog device */
 472                         mei_wdt_stop(wdt);
 473                         mei_wdt_register(wdt);
 474                 }
 475                 return;
 476         }
 477
 478         dev_warn(&cldev->dev, "not in correct state %s[%d]\n",
 479                          mei_wdt_state_str(wdt->state), wdt->state);
 480
 481 out:
 482         if (!completion_done(&wdt->response))
 483                 complete(&wdt->response);
 484 }
 485
 486 /*
 487  * mei_wdt_notif - callback for event notification
 488  *
 489  * @cldev: bus device
 490  */
 491 static void mei_wdt_notif(struct mei_cl_device *cldev)
 492 {
 493         struct mei_wdt *wdt = mei_cldev_get_drvdata(cldev);
 494
 495         if (wdt->state != MEI_WDT_NOT_REQUIRED)
 496                 return;
 497
 498         mei_wdt_register(wdt);
 499 }
 500
 501 #if IS_ENABLED(CONFIG_DEBUG_FS)
 502
 503 static ssize_t mei_dbgfs_read_activation(struct file *file, char __user *ubuf,
 504                                         size_t cnt, loff_t *ppos)
 505 {
 506         struct mei_wdt *wdt = file->private_data;
 507         const size_t bufsz = 32;
 508         char buf[32];
 509         ssize_t pos;
 510
 511         mutex_lock(&wdt->reg_lock);
 512         pos = scnprintf(buf, bufsz, "%s\n",
 513                 __mei_wdt_is_registered(wdt) ? "activated" : "deactivated");
 514         mutex_unlock(&wdt->reg_lock);
 515
 516         return simple_read_from_buffer(ubuf, cnt, ppos, buf, pos);
 517 }
 518
 519 static const struct file_operations dbgfs_fops_activation = {
 520         .open    = simple_open,
 521         .read    = mei_dbgfs_read_activation,
 522         .llseek  = generic_file_llseek,
 523 };
 524
 525 static ssize_t mei_dbgfs_read_state(struct file *file, char __user *ubuf,
 526                                     size_t cnt, loff_t *ppos)
 527 {
 528         struct mei_wdt *wdt = file->private_data;
 529         const size_t bufsz = 32;
 530         char buf[bufsz];
 531         ssize_t pos;
 532
 533         pos = scnprintf(buf, bufsz, "state: %s\n",
 534                          mei_wdt_state_str(wdt->state));
 535
 536         return simple_read_from_buffer(ubuf, cnt, ppos, buf, pos);
 537 }
 538
 539 static const struct file_operations dbgfs_fops_state = {
 540         .open = simple_open,
 541         .read = mei_dbgfs_read_state,
 542         .llseek = generic_file_llseek,
 543 };
 544
 545 static void dbgfs_unregister(struct mei_wdt *wdt)
 546 {
 547         debugfs_remove_recursive(wdt->dbgfs_dir);
 548         wdt->dbgfs_dir = NULL;
 549 }
 550
 551 static int dbgfs_register(struct mei_wdt *wdt)
 552 {
 553         struct dentry *dir, *f;
 554
 555         dir = debugfs_create_dir(KBUILD_MODNAME, NULL);
 556         if (!dir)
 557                 return -ENOMEM;
 558
 559         wdt->dbgfs_dir = dir;
 560         f = debugfs_create_file("state", S_IRUSR, dir, wdt, &dbgfs_fops_state);
 561         if (!f)
 562                 goto err;
 563
 564         f = debugfs_create_file("activation",  S_IRUSR,
 565                                 dir, wdt, &dbgfs_fops_activation);
 566         if (!f)
 567                 goto err;
 568
 569         return 0;
 570 err:
 571         dbgfs_unregister(wdt);
 572         return -ENODEV;
 573 }
 574
 575 #else
 576
 577 static inline void dbgfs_unregister(struct mei_wdt *wdt) {}
 578
 579 static inline int dbgfs_register(struct mei_wdt *wdt)
 580 {
 581         return 0;
 582 }
 583 #endif /* CONFIG_DEBUG_FS */
 584
 585 static int mei_wdt_probe(struct mei_cl_device *cldev,
 586                          const struct mei_cl_device_id *id)
 587 {
 588         struct mei_wdt *wdt;
 589         int ret;
 590
 591         wdt = kzalloc(sizeof(struct mei_wdt), GFP_KERNEL);
 592         if (!wdt)
 593                 return -ENOMEM;
 594
 595         wdt->timeout = MEI_WDT_DEFAULT_TIMEOUT;
 596         wdt->state = MEI_WDT_PROBE;
 597         wdt->cldev = cldev;
 598         wdt->resp_required = mei_cldev_ver(cldev) > 0x1;
 599         mutex_init(&wdt->reg_lock);
 600         init_completion(&wdt->response);
 601         INIT_WORK(&wdt->unregister, mei_wdt_unregister_work);
 602
 603         mei_cldev_set_drvdata(cldev, wdt);
 604
 605         ret = mei_cldev_enable(cldev);
 606         if (ret < 0) {
 607                 dev_err(&cldev->dev, "Could not enable cl device\n");
 608                 goto err_out;
 609         }
 610
 611         ret = mei_cldev_register_rx_cb(wdt->cldev, mei_wdt_rx);
 612         if (ret) {
 613                 dev_err(&cldev->dev, "Could not reg rx event ret=%d\n", ret);
 614                 goto err_disable;
 615         }
 616
 617         ret = mei_cldev_register_notif_cb(wdt->cldev, mei_wdt_notif);
 618         /* on legacy devices notification is not supported
 619          */
 620         if (ret && ret != -EOPNOTSUPP) {
 621                 dev_err(&cldev->dev, "Could not reg notif event ret=%d\n", ret);
 622                 goto err_disable;
 623         }
 624
 625         wd_info.firmware_version = mei_cldev_ver(cldev);
 626
 627         if (wdt->resp_required)
 628                 ret = mei_wdt_ping(wdt);
 629         else
 630                 ret = mei_wdt_register(wdt);
 631
 632         if (ret)
 633                 goto err_disable;
 634
 635         if (dbgfs_register(wdt))
 636                 dev_warn(&cldev->dev, "cannot register debugfs\n");
 637
 638         return 0;
 639
 640 err_disable:
 641         mei_cldev_disable(cldev);
 642
 643 err_out:
 644         kfree(wdt);
 645
 646         return ret;
 647 }
 648
 649 static int mei_wdt_remove(struct mei_cl_device *cldev)
 650 {
 651         struct mei_wdt *wdt = mei_cldev_get_drvdata(cldev);
 652
 653         /* Free the caller in case of fw initiated or unexpected reset */
 654         if (!completion_done(&wdt->response))
 655                 complete(&wdt->response);
 656
 657         cancel_work_sync(&wdt->unregister);
 658
 659         mei_wdt_unregister(wdt);
 660
 661         mei_cldev_disable(cldev);
 662
 663         dbgfs_unregister(wdt);
 664
 665         kfree(wdt);
 666
 667         return 0;
 668 }
 669
 670 #define MEI_UUID_WD UUID_LE(0x05B79A6F, 0x4628, 0x4D7F, \
 671                             0x89, 0x9D, 0xA9, 0x15, 0x14, 0xCB, 0x32, 0xAB)
 672
 673 static const struct mei_cl_device_id mei_wdt_tbl[] = {
 674         { .uuid = MEI_UUID_WD, .version = MEI_CL_VERSION_ANY },
 675         /* required last entry */
 676         { }
 677 };
 678 MODULE_DEVICE_TABLE(mei, mei_wdt_tbl);
 679
 680 static struct mei_cl_driver mei_wdt_driver = {
 681         .id_table = mei_wdt_tbl,
 682         .name = KBUILD_MODNAME,
 683
 684         .probe = mei_wdt_probe,
 685         .remove = mei_wdt_remove,
 686 };
 687
 688 module_mei_cl_driver(mei_wdt_driver);
 689
 690 MODULE_AUTHOR("Intel Corporation");
 691 MODULE_LICENSE("GPL");
 692 MODULE_DESCRIPTION("Device driver for Intel MEI iAMT watchdog");