drivers/misc/mei/main.c

   1 /*
   2  *
   3  * Intel Management Engine Interface (Intel MEI) Linux driver
   4  * Copyright (c) 2003-2012, Intel Corporation.
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms and conditions of the GNU General Public License,
   8  * version 2, as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  13  * more details.
  14  *
  15  */
  16 #include <linux/module.h>
  17 #include <linux/moduleparam.h>
  18 #include <linux/kernel.h>
  19 #include <linux/device.h>
  20 #include <linux/slab.h>
  21 #include <linux/fs.h>
  22 #include <linux/errno.h>
  23 #include <linux/types.h>
  24 #include <linux/fcntl.h>
  25 #include <linux/poll.h>
  26 #include <linux/init.h>
  27 #include <linux/ioctl.h>
  28 #include <linux/cdev.h>
  29 #include <linux/sched.h>
  30 #include <linux/uuid.h>
  31 #include <linux/compat.h>
  32 #include <linux/jiffies.h>
  33 #include <linux/interrupt.h>
  34
  35 #include <linux/mei.h>
  36
  37 #include "mei_dev.h"
  38 #include "client.h"
  39
  40 /**
  41  * mei_open - the open function
  42  *
  43  * @inode: pointer to inode structure
  44  * @file: pointer to file structure
  45  *
  46  * Return: 0 on success, <0 on error
  47  */
  48 static int mei_open(struct inode *inode, struct file *file)
  49 {
  50         struct mei_device *dev;
  51         struct mei_cl *cl;
  52
  53         int err;
  54
  55         dev = container_of(inode->i_cdev, struct mei_device, cdev);
  56         if (!dev)
  57                 return -ENODEV;
  58
  59         mutex_lock(&dev->device_lock);
  60
  61         if (dev->dev_state != MEI_DEV_ENABLED) {
  62                 dev_dbg(dev->dev, "dev_state != MEI_ENABLED  dev_state = %s\n",
  63                     mei_dev_state_str(dev->dev_state));
  64                 err = -ENODEV;
  65                 goto err_unlock;
  66         }
  67
  68         cl = mei_cl_alloc_linked(dev, MEI_HOST_CLIENT_ID_ANY);
  69         if (IS_ERR(cl)) {
  70                 err = PTR_ERR(cl);
  71                 goto err_unlock;
  72         }
  73
  74         file->private_data = cl;
  75
  76         mutex_unlock(&dev->device_lock);
  77
  78         return nonseekable_open(inode, file);
  79
  80 err_unlock:
  81         mutex_unlock(&dev->device_lock);
  82         return err;
  83 }
  84
  85 /**
  86  * mei_release - the release function
  87  *
  88  * @inode: pointer to inode structure
  89  * @file: pointer to file structure
  90  *
  91  * Return: 0 on success, <0 on error
  92  */
  93 static int mei_release(struct inode *inode, struct file *file)
  94 {
  95         struct mei_cl *cl = file->private_data;
  96         struct mei_device *dev;
  97         int rets;
  98
  99         if (WARN_ON(!cl || !cl->dev))
 100                 return -ENODEV;
 101
 102         dev = cl->dev;
 103
 104         mutex_lock(&dev->device_lock);
 105         if (cl == &dev->iamthif_cl) {
 106                 rets = mei_amthif_release(dev, file);
 107                 goto out;
 108         }
 109         rets = mei_cl_disconnect(cl);
 110
 111         mei_cl_flush_queues(cl, file);
 112         cl_dbg(dev, cl, "removing\n");
 113
 114         mei_cl_unlink(cl);
 115
 116         file->private_data = NULL;
 117
 118         kfree(cl);
 119 out:
 120         mutex_unlock(&dev->device_lock);
 121         return rets;
 122 }
 123
 124
 125 /**
 126  * mei_read - the read function.
 127  *
 128  * @file: pointer to file structure
 129  * @ubuf: pointer to user buffer
 130  * @length: buffer length
 131  * @offset: data offset in buffer
 132  *
 133  * Return: >=0 data length on success , <0 on error
 134  */
 135 static ssize_t mei_read(struct file *file, char __user *ubuf,
 136                         size_t length, loff_t *offset)
 137 {
 138         struct mei_cl *cl = file->private_data;
 139         struct mei_device *dev;
 140         struct mei_cl_cb *cb = NULL;
 141         int rets;
 142         int err;
 143
 144
 145         if (WARN_ON(!cl || !cl->dev))
 146                 return -ENODEV;
 147
 148         dev = cl->dev;
 149
 150
 151         mutex_lock(&dev->device_lock);
 152         if (dev->dev_state != MEI_DEV_ENABLED) {
 153                 rets = -ENODEV;
 154                 goto out;
 155         }
 156
 157         if (length == 0) {
 158                 rets = 0;
 159                 goto out;
 160         }
 161
 162         if (cl == &dev->iamthif_cl) {
 163                 rets = mei_amthif_read(dev, file, ubuf, length, offset);
 164                 goto out;
 165         }
 166
 167         cb = mei_cl_read_cb(cl, file);
 168         if (cb) {
 169                 /* read what left */
 170                 if (cb->buf_idx > *offset)
 171                         goto copy_buffer;
 172                 /* offset is beyond buf_idx we have no more data return 0 */
 173                 if (cb->buf_idx > 0 && cb->buf_idx <= *offset) {
 174                         rets = 0;
 175                         goto free;
 176                 }
 177                 /* Offset needs to be cleaned for contiguous reads*/
 178                 if (cb->buf_idx == 0 && *offset > 0)
 179                         *offset = 0;
 180         } else if (*offset > 0) {
 181                 *offset = 0;
 182         }
 183
 184         err = mei_cl_read_start(cl, length, file);
 185         if (err && err != -EBUSY) {
 186                 dev_dbg(dev->dev,
 187                         "mei start read failure with status = %d\n", err);
 188                 rets = err;
 189                 goto out;
 190         }
 191
 192         if (list_empty(&cl->rd_completed) && !waitqueue_active(&cl->rx_wait)) {
 193                 if (file->f_flags & O_NONBLOCK) {
 194                         rets = -EAGAIN;
 195                         goto out;
 196                 }
 197
 198                 mutex_unlock(&dev->device_lock);
 199
 200                 if (wait_event_interruptible(cl->rx_wait,
 201                                 (!list_empty(&cl->rd_completed)) ||
 202                                 (!mei_cl_is_connected(cl)))) {
 203
 204                         if (signal_pending(current))
 205                                 return -EINTR;
 206                         return -ERESTARTSYS;
 207                 }
 208
 209                 mutex_lock(&dev->device_lock);
 210                 if (!mei_cl_is_connected(cl)) {
 211                         rets = -EBUSY;
 212                         goto out;
 213                 }
 214         }
 215
 216         cb = mei_cl_read_cb(cl, file);
 217         if (!cb) {
 218                 if (mei_cl_is_fixed_address(cl) && dev->allow_fixed_address) {
 219                         cb = mei_cl_read_cb(cl, NULL);
 220                         if (cb)
 221                                 goto copy_buffer;
 222                 }
 223                 rets = 0;
 224                 goto out;
 225         }
 226
 227 copy_buffer:
 228         /* now copy the data to user space */
 229         if (cb->status) {
 230                 rets = cb->status;
 231                 dev_dbg(dev->dev, "read operation failed %d\n", rets);
 232                 goto free;
 233         }
 234
 235         dev_dbg(dev->dev, "buf.size = %d buf.idx= %ld\n",
 236             cb->buf.size, cb->buf_idx);
 237         if (length == 0 || ubuf == NULL || *offset > cb->buf_idx) {
 238                 rets = -EMSGSIZE;
 239                 goto free;
 240         }
 241
 242         /* length is being truncated to PAGE_SIZE,
 243          * however buf_idx may point beyond that */
 244         length = min_t(size_t, length, cb->buf_idx - *offset);
 245
 246         if (copy_to_user(ubuf, cb->buf.data + *offset, length)) {
 247                 dev_dbg(dev->dev, "failed to copy data to userland\n");
 248                 rets = -EFAULT;
 249                 goto free;
 250         }
 251
 252         rets = length;
 253         *offset += length;
 254         if ((unsigned long)*offset < cb->buf_idx)
 255                 goto out;
 256
 257 free:
 258         mei_io_cb_free(cb);
 259
 260 out:
 261         dev_dbg(dev->dev, "end mei read rets= %d\n", rets);
 262         mutex_unlock(&dev->device_lock);
 263         return rets;
 264 }
 265 /**
 266  * mei_write - the write function.
 267  *
 268  * @file: pointer to file structure
 269  * @ubuf: pointer to user buffer
 270  * @length: buffer length
 271  * @offset: data offset in buffer
 272  *
 273  * Return: >=0 data length on success , <0 on error
 274  */
 275 static ssize_t mei_write(struct file *file, const char __user *ubuf,
 276                          size_t length, loff_t *offset)
 277 {
 278         struct mei_cl *cl = file->private_data;
 279         struct mei_cl_cb *write_cb = NULL;
 280         struct mei_device *dev;
 281         unsigned long timeout = 0;
 282         int rets;
 283
 284         if (WARN_ON(!cl || !cl->dev))
 285                 return -ENODEV;
 286
 287         dev = cl->dev;
 288
 289         mutex_lock(&dev->device_lock);
 290
 291         if (dev->dev_state != MEI_DEV_ENABLED) {
 292                 rets = -ENODEV;
 293                 goto out;
 294         }
 295
 296         if (!mei_cl_is_connected(cl)) {
 297                 cl_err(dev, cl, "is not connected");
 298                 rets = -ENODEV;
 299                 goto out;
 300         }
 301
 302         if (!mei_me_cl_is_active(cl->me_cl)) {
 303                 rets = -ENOTTY;
 304                 goto out;
 305         }
 306
 307         if (length > mei_cl_mtu(cl)) {
 308                 rets = -EFBIG;
 309                 goto out;
 310         }
 311
 312         if (length == 0) {
 313                 rets = 0;
 314                 goto out;
 315         }
 316
 317         if (cl == &dev->iamthif_cl) {
 318                 write_cb = mei_amthif_find_read_list_entry(dev, file);
 319
 320                 if (write_cb) {
 321                         timeout = write_cb->read_time +
 322                                 mei_secs_to_jiffies(MEI_IAMTHIF_READ_TIMER);
 323
 324                         if (time_after(jiffies, timeout)) {
 325                                 *offset = 0;
 326                                 mei_io_cb_free(write_cb);
 327                                 write_cb = NULL;
 328                         }
 329                 }
 330         }
 331
 332         *offset = 0;
 333         write_cb = mei_cl_alloc_cb(cl, length, MEI_FOP_WRITE, file);
 334         if (!write_cb) {
 335                 rets = -ENOMEM;
 336                 goto out;
 337         }
 338
 339         rets = copy_from_user(write_cb->buf.data, ubuf, length);
 340         if (rets) {
 341                 dev_dbg(dev->dev, "failed to copy data from userland\n");
 342                 rets = -EFAULT;
 343                 goto out;
 344         }
 345
 346         if (cl == &dev->iamthif_cl) {
 347                 rets = mei_amthif_write(cl, write_cb);
 348
 349                 if (rets) {
 350                         dev_err(dev->dev,
 351                                 "amthif write failed with status = %d\n", rets);
 352                         goto out;
 353                 }
 354                 mutex_unlock(&dev->device_lock);
 355                 return length;
 356         }
 357
 358         rets = mei_cl_write(cl, write_cb, false);
 359 out:
 360         mutex_unlock(&dev->device_lock);
 361         if (rets < 0)
 362                 mei_io_cb_free(write_cb);
 363         return rets;
 364 }
 365
 366 /**
 367  * mei_ioctl_connect_client - the connect to fw client IOCTL function
 368  *
 369  * @file: private data of the file object
 370  * @data: IOCTL connect data, input and output parameters
 371  *
 372  * Locking: called under "dev->device_lock" lock
 373  *
 374  * Return: 0 on success, <0 on failure.
 375  */
 376 static int mei_ioctl_connect_client(struct file *file,
 377                         struct mei_connect_client_data *data)
 378 {
 379         struct mei_device *dev;
 380         struct mei_client *client;
 381         struct mei_me_client *me_cl;
 382         struct mei_cl *cl;
 383         int rets;
 384
 385         cl = file->private_data;
 386         dev = cl->dev;
 387
 388         if (dev->dev_state != MEI_DEV_ENABLED)
 389                 return -ENODEV;
 390
 391         if (cl->state != MEI_FILE_INITIALIZING &&
 392             cl->state != MEI_FILE_DISCONNECTED)
 393                 return  -EBUSY;
 394
 395         /* find ME client we're trying to connect to */
 396         me_cl = mei_me_cl_by_uuid(dev, &data->in_client_uuid);
 397         if (!me_cl ||
 398             (me_cl->props.fixed_address && !dev->allow_fixed_address)) {
 399                 dev_dbg(dev->dev, "Cannot connect to FW Client UUID = %pUl\n",
 400                         &data->in_client_uuid);
 401                 mei_me_cl_put(me_cl);
 402                 return  -ENOTTY;
 403         }
 404
 405         dev_dbg(dev->dev, "Connect to FW Client ID = %d\n",
 406                         me_cl->client_id);
 407         dev_dbg(dev->dev, "FW Client - Protocol Version = %d\n",
 408                         me_cl->props.protocol_version);
 409         dev_dbg(dev->dev, "FW Client - Max Msg Len = %d\n",
 410                         me_cl->props.max_msg_length);
 411
 412         /* if we're connecting to amthif client then we will use the
 413          * existing connection
 414          */
 415         if (uuid_le_cmp(data->in_client_uuid, mei_amthif_guid) == 0) {
 416                 dev_dbg(dev->dev, "FW Client is amthi\n");
 417                 if (!mei_cl_is_connected(&dev->iamthif_cl)) {
 418                         rets = -ENODEV;
 419                         goto end;
 420                 }
 421                 mei_cl_unlink(cl);
 422
 423                 kfree(cl);
 424                 cl = NULL;
 425                 dev->iamthif_open_count++;
 426                 file->private_data = &dev->iamthif_cl;
 427
 428                 client = &data->out_client_properties;
 429                 client->max_msg_length = me_cl->props.max_msg_length;
 430                 client->protocol_version = me_cl->props.protocol_version;
 431                 rets = dev->iamthif_cl.status;
 432
 433                 goto end;
 434         }
 435
 436         /* prepare the output buffer */
 437         client = &data->out_client_properties;
 438         client->max_msg_length = me_cl->props.max_msg_length;
 439         client->protocol_version = me_cl->props.protocol_version;
 440         dev_dbg(dev->dev, "Can connect?\n");
 441
 442         rets = mei_cl_connect(cl, me_cl, file);
 443
 444 end:
 445         mei_me_cl_put(me_cl);
 446         return rets;
 447 }
 448
 449 /**
 450  * mei_ioctl - the IOCTL function
 451  *
 452  * @file: pointer to file structure
 453  * @cmd: ioctl command
 454  * @data: pointer to mei message structure
 455  *
 456  * Return: 0 on success , <0 on error
 457  */
 458 static long mei_ioctl(struct file *file, unsigned int cmd, unsigned long data)
 459 {
 460         struct mei_device *dev;
 461         struct mei_cl *cl = file->private_data;
 462         struct mei_connect_client_data connect_data;
 463         int rets;
 464
 465
 466         if (WARN_ON(!cl || !cl->dev))
 467                 return -ENODEV;
 468
 469         dev = cl->dev;
 470
 471         dev_dbg(dev->dev, "IOCTL cmd = 0x%x", cmd);
 472
 473         mutex_lock(&dev->device_lock);
 474         if (dev->dev_state != MEI_DEV_ENABLED) {
 475                 rets = -ENODEV;
 476                 goto out;
 477         }
 478
 479         switch (cmd) {
 480         case IOCTL_MEI_CONNECT_CLIENT:
 481                 dev_dbg(dev->dev, ": IOCTL_MEI_CONNECT_CLIENT.\n");
 482                 if (copy_from_user(&connect_data, (char __user *)data,
 483                                 sizeof(struct mei_connect_client_data))) {
 484                         dev_dbg(dev->dev, "failed to copy data from userland\n");
 485                         rets = -EFAULT;
 486                         goto out;
 487                 }
 488
 489                 rets = mei_ioctl_connect_client(file, &connect_data);
 490                 if (rets)
 491                         goto out;
 492
 493                 /* if all is ok, copying the data back to user. */
 494                 if (copy_to_user((char __user *)data, &connect_data,
 495                                 sizeof(struct mei_connect_client_data))) {
 496                         dev_dbg(dev->dev, "failed to copy data to userland\n");
 497                         rets = -EFAULT;
 498                         goto out;
 499                 }
 500
 501                 break;
 502
 503         default:
 504                 dev_err(dev->dev, ": unsupported ioctl %d.\n", cmd);
 505                 rets = -ENOIOCTLCMD;
 506         }
 507
 508 out:
 509         mutex_unlock(&dev->device_lock);
 510         return rets;
 511 }
 512
 513 /**
 514  * mei_compat_ioctl - the compat IOCTL function
 515  *
 516  * @file: pointer to file structure
 517  * @cmd: ioctl command
 518  * @data: pointer to mei message structure
 519  *
 520  * Return: 0 on success , <0 on error
 521  */
 522 #ifdef CONFIG_COMPAT
 523 static long mei_compat_ioctl(struct file *file,
 524                         unsigned int cmd, unsigned long data)
 525 {
 526         return mei_ioctl(file, cmd, (unsigned long)compat_ptr(data));
 527 }
 528 #endif
 529
 530
 531 /**
 532  * mei_poll - the poll function
 533  *
 534  * @file: pointer to file structure
 535  * @wait: pointer to poll_table structure
 536  *
 537  * Return: poll mask
 538  */
 539 static unsigned int mei_poll(struct file *file, poll_table *wait)
 540 {
 541         unsigned long req_events = poll_requested_events(wait);
 542         struct mei_cl *cl = file->private_data;
 543         struct mei_device *dev;
 544         unsigned int mask = 0;
 545
 546         if (WARN_ON(!cl || !cl->dev))
 547                 return POLLERR;
 548
 549         dev = cl->dev;
 550
 551         mutex_lock(&dev->device_lock);
 552
 553
 554         if (dev->dev_state != MEI_DEV_ENABLED ||
 555             !mei_cl_is_connected(cl)) {
 556                 mask = POLLERR;
 557                 goto out;
 558         }
 559
 560         if (cl == &dev->iamthif_cl) {
 561                 mask = mei_amthif_poll(dev, file, wait);
 562                 goto out;
 563         }
 564
 565         if (req_events & (POLLIN | POLLRDNORM)) {
 566                 poll_wait(file, &cl->rx_wait, wait);
 567
 568                 if (!list_empty(&cl->rd_completed))
 569                         mask |= POLLIN | POLLRDNORM;
 570                 else
 571                         mei_cl_read_start(cl, 0, file);
 572         }
 573
 574 out:
 575         mutex_unlock(&dev->device_lock);
 576         return mask;
 577 }
 578
 579 /**
 580  * fw_status_show - mei device attribute show method
 581  *
 582  * @device: device pointer
 583  * @attr: attribute pointer
 584  * @buf:  char out buffer
 585  *
 586  * Return: number of the bytes printed into buf or error
 587  */
 588 static ssize_t fw_status_show(struct device *device,
 589                 struct device_attribute *attr, char *buf)
 590 {
 591         struct mei_device *dev = dev_get_drvdata(device);
 592         struct mei_fw_status fw_status;
 593         int err, i;
 594         ssize_t cnt = 0;
 595
 596         mutex_lock(&dev->device_lock);
 597         err = mei_fw_status(dev, &fw_status);
 598         mutex_unlock(&dev->device_lock);
 599         if (err) {
 600                 dev_err(device, "read fw_status error = %d\n", err);
 601                 return err;
 602         }
 603
 604         for (i = 0; i < fw_status.count; i++)
 605                 cnt += scnprintf(buf + cnt, PAGE_SIZE - cnt, "%08X\n",
 606                                 fw_status.status[i]);
 607         return cnt;
 608 }
 609 static DEVICE_ATTR_RO(fw_status);
 610
 611 static struct attribute *mei_attrs[] = {
 612         &dev_attr_fw_status.attr,
 613         NULL
 614 };
 615 ATTRIBUTE_GROUPS(mei);
 616
 617 /*
 618  * file operations structure will be used for mei char device.
 619  */
 620 static const struct file_operations mei_fops = {
 621         .owner = THIS_MODULE,
 622         .read = mei_read,
 623         .unlocked_ioctl = mei_ioctl,
 624 #ifdef CONFIG_COMPAT
 625         .compat_ioctl = mei_compat_ioctl,
 626 #endif
 627         .open = mei_open,
 628         .release = mei_release,
 629         .write = mei_write,
 630         .poll = mei_poll,
 631         .llseek = no_llseek
 632 };
 633
 634 static struct class *mei_class;
 635 static dev_t mei_devt;
 636 #define MEI_MAX_DEVS  MINORMASK
 637 static DEFINE_MUTEX(mei_minor_lock);
 638 static DEFINE_IDR(mei_idr);
 639
 640 /**
 641  * mei_minor_get - obtain next free device minor number
 642  *
 643  * @dev:  device pointer
 644  *
 645  * Return: allocated minor, or -ENOSPC if no free minor left
 646  */
 647 static int mei_minor_get(struct mei_device *dev)
 648 {
 649         int ret;
 650
 651         mutex_lock(&mei_minor_lock);
 652         ret = idr_alloc(&mei_idr, dev, 0, MEI_MAX_DEVS, GFP_KERNEL);
 653         if (ret >= 0)
 654                 dev->minor = ret;
 655         else if (ret == -ENOSPC)
 656                 dev_err(dev->dev, "too many mei devices\n");
 657
 658         mutex_unlock(&mei_minor_lock);
 659         return ret;
 660 }
 661
 662 /**
 663  * mei_minor_free - mark device minor number as free
 664  *
 665  * @dev:  device pointer
 666  */
 667 static void mei_minor_free(struct mei_device *dev)
 668 {
 669         mutex_lock(&mei_minor_lock);
 670         idr_remove(&mei_idr, dev->minor);
 671         mutex_unlock(&mei_minor_lock);
 672 }
 673
 674 int mei_register(struct mei_device *dev, struct device *parent)
 675 {
 676         struct device *clsdev; /* class device */
 677         int ret, devno;
 678
 679         ret = mei_minor_get(dev);
 680         if (ret < 0)
 681                 return ret;
 682
 683         /* Fill in the data structures */
 684         devno = MKDEV(MAJOR(mei_devt), dev->minor);
 685         cdev_init(&dev->cdev, &mei_fops);
 686         dev->cdev.owner = mei_fops.owner;
 687
 688         /* Add the device */
 689         ret = cdev_add(&dev->cdev, devno, 1);
 690         if (ret) {
 691                 dev_err(parent, "unable to add device %d:%d\n",
 692                         MAJOR(mei_devt), dev->minor);
 693                 goto err_dev_add;
 694         }
 695
 696         clsdev = device_create_with_groups(mei_class, parent, devno,
 697                                            dev, mei_groups,
 698                                            "mei%d", dev->minor);
 699
 700         if (IS_ERR(clsdev)) {
 701                 dev_err(parent, "unable to create device %d:%d\n",
 702                         MAJOR(mei_devt), dev->minor);
 703                 ret = PTR_ERR(clsdev);
 704                 goto err_dev_create;
 705         }
 706
 707         ret = mei_dbgfs_register(dev, dev_name(clsdev));
 708         if (ret) {
 709                 dev_err(clsdev, "cannot register debugfs ret = %d\n", ret);
 710                 goto err_dev_dbgfs;
 711         }
 712
 713         return 0;
 714
 715 err_dev_dbgfs:
 716         device_destroy(mei_class, devno);
 717 err_dev_create:
 718         cdev_del(&dev->cdev);
 719 err_dev_add:
 720         mei_minor_free(dev);
 721         return ret;
 722 }
 723 EXPORT_SYMBOL_GPL(mei_register);
 724
 725 void mei_deregister(struct mei_device *dev)
 726 {
 727         int devno;
 728
 729         devno = dev->cdev.dev;
 730         cdev_del(&dev->cdev);
 731
 732         mei_dbgfs_deregister(dev);
 733
 734         device_destroy(mei_class, devno);
 735
 736         mei_minor_free(dev);
 737 }
 738 EXPORT_SYMBOL_GPL(mei_deregister);
 739
 740 static int __init mei_init(void)
 741 {
 742         int ret;
 743
 744         mei_class = class_create(THIS_MODULE, "mei");
 745         if (IS_ERR(mei_class)) {
 746                 pr_err("couldn't create class\n");
 747                 ret = PTR_ERR(mei_class);
 748                 goto err;
 749         }
 750
 751         ret = alloc_chrdev_region(&mei_devt, 0, MEI_MAX_DEVS, "mei");
 752         if (ret < 0) {
 753                 pr_err("unable to allocate char dev region\n");
 754                 goto err_class;
 755         }
 756
 757         ret = mei_cl_bus_init();
 758         if (ret < 0) {
 759                 pr_err("unable to initialize bus\n");
 760                 goto err_chrdev;
 761         }
 762
 763         return 0;
 764
 765 err_chrdev:
 766         unregister_chrdev_region(mei_devt, MEI_MAX_DEVS);
 767 err_class:
 768         class_destroy(mei_class);
 769 err:
 770         return ret;
 771 }
 772
 773 static void __exit mei_exit(void)
 774 {
 775         unregister_chrdev_region(mei_devt, MEI_MAX_DEVS);
 776         class_destroy(mei_class);
 777         mei_cl_bus_exit();
 778 }
 779
 780 module_init(mei_init);
 781 module_exit(mei_exit);
 782
 783 MODULE_AUTHOR("Intel Corporation");
 784 MODULE_DESCRIPTION("Intel(R) Management Engine Interface");
 785 MODULE_LICENSE("GPL v2");
 786