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                 cl_dbg(dev, cl, "mei start read failure status = %d\n", err);
 187                 rets = err;
 188                 goto out;
 189         }
 190
 191         if (list_empty(&cl->rd_completed) && !waitqueue_active(&cl->rx_wait)) {
 192                 if (file->f_flags & O_NONBLOCK) {
 193                         rets = -EAGAIN;
 194                         goto out;
 195                 }
 196
 197                 mutex_unlock(&dev->device_lock);
 198
 199                 if (wait_event_interruptible(cl->rx_wait,
 200                                 (!list_empty(&cl->rd_completed)) ||
 201                                 (!mei_cl_is_connected(cl)))) {
 202
 203                         if (signal_pending(current))
 204                                 return -EINTR;
 205                         return -ERESTARTSYS;
 206                 }
 207
 208                 mutex_lock(&dev->device_lock);
 209                 if (!mei_cl_is_connected(cl)) {
 210                         rets = -EBUSY;
 211                         goto out;
 212                 }
 213         }
 214
 215         cb = mei_cl_read_cb(cl, file);
 216         if (!cb) {
 217                 if (mei_cl_is_fixed_address(cl) && dev->allow_fixed_address) {
 218                         cb = mei_cl_read_cb(cl, NULL);
 219                         if (cb)
 220                                 goto copy_buffer;
 221                 }
 222                 rets = 0;
 223                 goto out;
 224         }
 225
 226 copy_buffer:
 227         /* now copy the data to user space */
 228         if (cb->status) {
 229                 rets = cb->status;
 230                 cl_dbg(dev, cl, "read operation failed %d\n", rets);
 231                 goto free;
 232         }
 233
 234         cl_dbg(dev, cl, "buf.size = %d buf.idx = %ld\n",
 235             cb->buf.size, cb->buf_idx);
 236         if (length == 0 || ubuf == NULL || *offset > cb->buf_idx) {
 237                 rets = -EMSGSIZE;
 238                 goto free;
 239         }
 240
 241         /* length is being truncated to PAGE_SIZE,
 242          * however buf_idx may point beyond that */
 243         length = min_t(size_t, length, cb->buf_idx - *offset);
 244
 245         if (copy_to_user(ubuf, cb->buf.data + *offset, length)) {
 246                 dev_dbg(dev->dev, "failed to copy data to userland\n");
 247                 rets = -EFAULT;
 248                 goto free;
 249         }
 250
 251         rets = length;
 252         *offset += length;
 253         if ((unsigned long)*offset < cb->buf_idx)
 254                 goto out;
 255
 256 free:
 257         mei_io_cb_free(cb);
 258
 259 out:
 260         cl_dbg(dev, cl, "end mei read rets = %d\n", rets);
 261         mutex_unlock(&dev->device_lock);
 262         return rets;
 263 }
 264 /**
 265  * mei_write - the write function.
 266  *
 267  * @file: pointer to file structure
 268  * @ubuf: pointer to user buffer
 269  * @length: buffer length
 270  * @offset: data offset in buffer
 271  *
 272  * Return: >=0 data length on success , <0 on error
 273  */
 274 static ssize_t mei_write(struct file *file, const char __user *ubuf,
 275                          size_t length, loff_t *offset)
 276 {
 277         struct mei_cl *cl = file->private_data;
 278         struct mei_cl_cb *write_cb = NULL;
 279         struct mei_device *dev;
 280         unsigned long timeout = 0;
 281         int rets;
 282
 283         if (WARN_ON(!cl || !cl->dev))
 284                 return -ENODEV;
 285
 286         dev = cl->dev;
 287
 288         mutex_lock(&dev->device_lock);
 289
 290         if (dev->dev_state != MEI_DEV_ENABLED) {
 291                 rets = -ENODEV;
 292                 goto out;
 293         }
 294
 295         if (!mei_cl_is_connected(cl)) {
 296                 cl_err(dev, cl, "is not connected");
 297                 rets = -ENODEV;
 298                 goto out;
 299         }
 300
 301         if (!mei_me_cl_is_active(cl->me_cl)) {
 302                 rets = -ENOTTY;
 303                 goto out;
 304         }
 305
 306         if (length > mei_cl_mtu(cl)) {
 307                 rets = -EFBIG;
 308                 goto out;
 309         }
 310
 311         if (length == 0) {
 312                 rets = 0;
 313                 goto out;
 314         }
 315
 316         if (cl == &dev->iamthif_cl) {
 317                 write_cb = mei_amthif_find_read_list_entry(dev, file);
 318
 319                 if (write_cb) {
 320                         timeout = write_cb->read_time +
 321                                 mei_secs_to_jiffies(MEI_IAMTHIF_READ_TIMER);
 322
 323                         if (time_after(jiffies, timeout)) {
 324                                 *offset = 0;
 325                                 mei_io_cb_free(write_cb);
 326                                 write_cb = NULL;
 327                         }
 328                 }
 329         }
 330
 331         *offset = 0;
 332         write_cb = mei_cl_alloc_cb(cl, length, MEI_FOP_WRITE, file);
 333         if (!write_cb) {
 334                 rets = -ENOMEM;
 335                 goto out;
 336         }
 337
 338         rets = copy_from_user(write_cb->buf.data, ubuf, length);
 339         if (rets) {
 340                 dev_dbg(dev->dev, "failed to copy data from userland\n");
 341                 rets = -EFAULT;
 342                 goto out;
 343         }
 344
 345         if (cl == &dev->iamthif_cl) {
 346                 rets = mei_amthif_write(cl, write_cb);
 347
 348                 if (rets) {
 349                         dev_err(dev->dev,
 350                                 "amthif write failed with status = %d\n", rets);
 351                         goto out;
 352                 }
 353                 mutex_unlock(&dev->device_lock);
 354                 return length;
 355         }
 356
 357         rets = mei_cl_write(cl, write_cb, false);
 358 out:
 359         mutex_unlock(&dev->device_lock);
 360         if (rets < 0)
 361                 mei_io_cb_free(write_cb);
 362         return rets;
 363 }
 364
 365 /**
 366  * mei_ioctl_connect_client - the connect to fw client IOCTL function
 367  *
 368  * @file: private data of the file object
 369  * @data: IOCTL connect data, input and output parameters
 370  *
 371  * Locking: called under "dev->device_lock" lock
 372  *
 373  * Return: 0 on success, <0 on failure.
 374  */
 375 static int mei_ioctl_connect_client(struct file *file,
 376                         struct mei_connect_client_data *data)
 377 {
 378         struct mei_device *dev;
 379         struct mei_client *client;
 380         struct mei_me_client *me_cl;
 381         struct mei_cl *cl;
 382         int rets;
 383
 384         cl = file->private_data;
 385         dev = cl->dev;
 386
 387         if (dev->dev_state != MEI_DEV_ENABLED)
 388                 return -ENODEV;
 389
 390         if (cl->state != MEI_FILE_INITIALIZING &&
 391             cl->state != MEI_FILE_DISCONNECTED)
 392                 return  -EBUSY;
 393
 394         /* find ME client we're trying to connect to */
 395         me_cl = mei_me_cl_by_uuid(dev, &data->in_client_uuid);
 396         if (!me_cl ||
 397             (me_cl->props.fixed_address && !dev->allow_fixed_address)) {
 398                 dev_dbg(dev->dev, "Cannot connect to FW Client UUID = %pUl\n",
 399                         &data->in_client_uuid);
 400                 mei_me_cl_put(me_cl);
 401                 return  -ENOTTY;
 402         }
 403
 404         dev_dbg(dev->dev, "Connect to FW Client ID = %d\n",
 405                         me_cl->client_id);
 406         dev_dbg(dev->dev, "FW Client - Protocol Version = %d\n",
 407                         me_cl->props.protocol_version);
 408         dev_dbg(dev->dev, "FW Client - Max Msg Len = %d\n",
 409                         me_cl->props.max_msg_length);
 410
 411         /* if we're connecting to amthif client then we will use the
 412          * existing connection
 413          */
 414         if (uuid_le_cmp(data->in_client_uuid, mei_amthif_guid) == 0) {
 415                 dev_dbg(dev->dev, "FW Client is amthi\n");
 416                 if (!mei_cl_is_connected(&dev->iamthif_cl)) {
 417                         rets = -ENODEV;
 418                         goto end;
 419                 }
 420                 mei_cl_unlink(cl);
 421
 422                 kfree(cl);
 423                 cl = NULL;
 424                 dev->iamthif_open_count++;
 425                 file->private_data = &dev->iamthif_cl;
 426
 427                 client = &data->out_client_properties;
 428                 client->max_msg_length = me_cl->props.max_msg_length;
 429                 client->protocol_version = me_cl->props.protocol_version;
 430                 rets = dev->iamthif_cl.status;
 431
 432                 goto end;
 433         }
 434
 435         /* prepare the output buffer */
 436         client = &data->out_client_properties;
 437         client->max_msg_length = me_cl->props.max_msg_length;
 438         client->protocol_version = me_cl->props.protocol_version;
 439         dev_dbg(dev->dev, "Can connect?\n");
 440
 441         rets = mei_cl_connect(cl, me_cl, file);
 442
 443 end:
 444         mei_me_cl_put(me_cl);
 445         return rets;
 446 }
 447
 448 /**
 449  * mei_ioctl - the IOCTL function
 450  *
 451  * @file: pointer to file structure
 452  * @cmd: ioctl command
 453  * @data: pointer to mei message structure
 454  *
 455  * Return: 0 on success , <0 on error
 456  */
 457 static long mei_ioctl(struct file *file, unsigned int cmd, unsigned long data)
 458 {
 459         struct mei_device *dev;
 460         struct mei_cl *cl = file->private_data;
 461         struct mei_connect_client_data connect_data;
 462         int rets;
 463
 464
 465         if (WARN_ON(!cl || !cl->dev))
 466                 return -ENODEV;
 467
 468         dev = cl->dev;
 469
 470         dev_dbg(dev->dev, "IOCTL cmd = 0x%x", cmd);
 471
 472         mutex_lock(&dev->device_lock);
 473         if (dev->dev_state != MEI_DEV_ENABLED) {
 474                 rets = -ENODEV;
 475                 goto out;
 476         }
 477
 478         switch (cmd) {
 479         case IOCTL_MEI_CONNECT_CLIENT:
 480                 dev_dbg(dev->dev, ": IOCTL_MEI_CONNECT_CLIENT.\n");
 481                 if (copy_from_user(&connect_data, (char __user *)data,
 482                                 sizeof(struct mei_connect_client_data))) {
 483                         dev_dbg(dev->dev, "failed to copy data from userland\n");
 484                         rets = -EFAULT;
 485                         goto out;
 486                 }
 487
 488                 rets = mei_ioctl_connect_client(file, &connect_data);
 489                 if (rets)
 490                         goto out;
 491
 492                 /* if all is ok, copying the data back to user. */
 493                 if (copy_to_user((char __user *)data, &connect_data,
 494                                 sizeof(struct mei_connect_client_data))) {
 495                         dev_dbg(dev->dev, "failed to copy data to userland\n");
 496                         rets = -EFAULT;
 497                         goto out;
 498                 }
 499
 500                 break;
 501
 502         default:
 503                 dev_err(dev->dev, ": unsupported ioctl %d.\n", cmd);
 504                 rets = -ENOIOCTLCMD;
 505         }
 506
 507 out:
 508         mutex_unlock(&dev->device_lock);
 509         return rets;
 510 }
 511
 512 /**
 513  * mei_compat_ioctl - the compat IOCTL function
 514  *
 515  * @file: pointer to file structure
 516  * @cmd: ioctl command
 517  * @data: pointer to mei message structure
 518  *
 519  * Return: 0 on success , <0 on error
 520  */
 521 #ifdef CONFIG_COMPAT
 522 static long mei_compat_ioctl(struct file *file,
 523                         unsigned int cmd, unsigned long data)
 524 {
 525         return mei_ioctl(file, cmd, (unsigned long)compat_ptr(data));
 526 }
 527 #endif
 528
 529
 530 /**
 531  * mei_poll - the poll function
 532  *
 533  * @file: pointer to file structure
 534  * @wait: pointer to poll_table structure
 535  *
 536  * Return: poll mask
 537  */
 538 static unsigned int mei_poll(struct file *file, poll_table *wait)
 539 {
 540         unsigned long req_events = poll_requested_events(wait);
 541         struct mei_cl *cl = file->private_data;
 542         struct mei_device *dev;
 543         unsigned int mask = 0;
 544
 545         if (WARN_ON(!cl || !cl->dev))
 546                 return POLLERR;
 547
 548         dev = cl->dev;
 549
 550         mutex_lock(&dev->device_lock);
 551
 552
 553         if (dev->dev_state != MEI_DEV_ENABLED ||
 554             !mei_cl_is_connected(cl)) {
 555                 mask = POLLERR;
 556                 goto out;
 557         }
 558
 559         if (cl == &dev->iamthif_cl) {
 560                 mask = mei_amthif_poll(dev, file, wait);
 561                 goto out;
 562         }
 563
 564         if (req_events & (POLLIN | POLLRDNORM)) {
 565                 poll_wait(file, &cl->rx_wait, wait);
 566
 567                 if (!list_empty(&cl->rd_completed))
 568                         mask |= POLLIN | POLLRDNORM;
 569                 else
 570                         mei_cl_read_start(cl, 0, file);
 571         }
 572
 573 out:
 574         mutex_unlock(&dev->device_lock);
 575         return mask;
 576 }
 577
 578 /**
 579  * fw_status_show - mei device attribute show method
 580  *
 581  * @device: device pointer
 582  * @attr: attribute pointer
 583  * @buf:  char out buffer
 584  *
 585  * Return: number of the bytes printed into buf or error
 586  */
 587 static ssize_t fw_status_show(struct device *device,
 588                 struct device_attribute *attr, char *buf)
 589 {
 590         struct mei_device *dev = dev_get_drvdata(device);
 591         struct mei_fw_status fw_status;
 592         int err, i;
 593         ssize_t cnt = 0;
 594
 595         mutex_lock(&dev->device_lock);
 596         err = mei_fw_status(dev, &fw_status);
 597         mutex_unlock(&dev->device_lock);
 598         if (err) {
 599                 dev_err(device, "read fw_status error = %d\n", err);
 600                 return err;
 601         }
 602
 603         for (i = 0; i < fw_status.count; i++)
 604                 cnt += scnprintf(buf + cnt, PAGE_SIZE - cnt, "%08X\n",
 605                                 fw_status.status[i]);
 606         return cnt;
 607 }
 608 static DEVICE_ATTR_RO(fw_status);
 609
 610 static struct attribute *mei_attrs[] = {
 611         &dev_attr_fw_status.attr,
 612         NULL
 613 };
 614 ATTRIBUTE_GROUPS(mei);
 615
 616 /*
 617  * file operations structure will be used for mei char device.
 618  */
 619 static const struct file_operations mei_fops = {
 620         .owner = THIS_MODULE,
 621         .read = mei_read,
 622         .unlocked_ioctl = mei_ioctl,
 623 #ifdef CONFIG_COMPAT
 624         .compat_ioctl = mei_compat_ioctl,
 625 #endif
 626         .open = mei_open,
 627         .release = mei_release,
 628         .write = mei_write,
 629         .poll = mei_poll,
 630         .llseek = no_llseek
 631 };
 632
 633 static struct class *mei_class;
 634 static dev_t mei_devt;
 635 #define MEI_MAX_DEVS  MINORMASK
 636 static DEFINE_MUTEX(mei_minor_lock);
 637 static DEFINE_IDR(mei_idr);
 638
 639 /**
 640  * mei_minor_get - obtain next free device minor number
 641  *
 642  * @dev:  device pointer
 643  *
 644  * Return: allocated minor, or -ENOSPC if no free minor left
 645  */
 646 static int mei_minor_get(struct mei_device *dev)
 647 {
 648         int ret;
 649
 650         mutex_lock(&mei_minor_lock);
 651         ret = idr_alloc(&mei_idr, dev, 0, MEI_MAX_DEVS, GFP_KERNEL);
 652         if (ret >= 0)
 653                 dev->minor = ret;
 654         else if (ret == -ENOSPC)
 655                 dev_err(dev->dev, "too many mei devices\n");
 656
 657         mutex_unlock(&mei_minor_lock);
 658         return ret;
 659 }
 660
 661 /**
 662  * mei_minor_free - mark device minor number as free
 663  *
 664  * @dev:  device pointer
 665  */
 666 static void mei_minor_free(struct mei_device *dev)
 667 {
 668         mutex_lock(&mei_minor_lock);
 669         idr_remove(&mei_idr, dev->minor);
 670         mutex_unlock(&mei_minor_lock);
 671 }
 672
 673 int mei_register(struct mei_device *dev, struct device *parent)
 674 {
 675         struct device *clsdev; /* class device */
 676         int ret, devno;
 677
 678         ret = mei_minor_get(dev);
 679         if (ret < 0)
 680                 return ret;
 681
 682         /* Fill in the data structures */
 683         devno = MKDEV(MAJOR(mei_devt), dev->minor);
 684         cdev_init(&dev->cdev, &mei_fops);
 685         dev->cdev.owner = parent->driver->owner;
 686
 687         /* Add the device */
 688         ret = cdev_add(&dev->cdev, devno, 1);
 689         if (ret) {
 690                 dev_err(parent, "unable to add device %d:%d\n",
 691                         MAJOR(mei_devt), dev->minor);
 692                 goto err_dev_add;
 693         }
 694
 695         clsdev = device_create_with_groups(mei_class, parent, devno,
 696                                            dev, mei_groups,
 697                                            "mei%d", dev->minor);
 698
 699         if (IS_ERR(clsdev)) {
 700                 dev_err(parent, "unable to create device %d:%d\n",
 701                         MAJOR(mei_devt), dev->minor);
 702                 ret = PTR_ERR(clsdev);
 703                 goto err_dev_create;
 704         }
 705
 706         ret = mei_dbgfs_register(dev, dev_name(clsdev));
 707         if (ret) {
 708                 dev_err(clsdev, "cannot register debugfs ret = %d\n", ret);
 709                 goto err_dev_dbgfs;
 710         }
 711
 712         return 0;
 713
 714 err_dev_dbgfs:
 715         device_destroy(mei_class, devno);
 716 err_dev_create:
 717         cdev_del(&dev->cdev);
 718 err_dev_add:
 719         mei_minor_free(dev);
 720         return ret;
 721 }
 722 EXPORT_SYMBOL_GPL(mei_register);
 723
 724 void mei_deregister(struct mei_device *dev)
 725 {
 726         int devno;
 727
 728         devno = dev->cdev.dev;
 729         cdev_del(&dev->cdev);
 730
 731         mei_dbgfs_deregister(dev);
 732
 733         device_destroy(mei_class, devno);
 734
 735         mei_minor_free(dev);
 736 }
 737 EXPORT_SYMBOL_GPL(mei_deregister);
 738
 739 static int __init mei_init(void)
 740 {
 741         int ret;
 742
 743         mei_class = class_create(THIS_MODULE, "mei");
 744         if (IS_ERR(mei_class)) {
 745                 pr_err("couldn't create class\n");
 746                 ret = PTR_ERR(mei_class);
 747                 goto err;
 748         }
 749
 750         ret = alloc_chrdev_region(&mei_devt, 0, MEI_MAX_DEVS, "mei");
 751         if (ret < 0) {
 752                 pr_err("unable to allocate char dev region\n");
 753                 goto err_class;
 754         }
 755
 756         ret = mei_cl_bus_init();
 757         if (ret < 0) {
 758                 pr_err("unable to initialize bus\n");
 759                 goto err_chrdev;
 760         }
 761
 762         return 0;
 763
 764 err_chrdev:
 765         unregister_chrdev_region(mei_devt, MEI_MAX_DEVS);
 766 err_class:
 767         class_destroy(mei_class);
 768 err:
 769         return ret;
 770 }
 771
 772 static void __exit mei_exit(void)
 773 {
 774         unregister_chrdev_region(mei_devt, MEI_MAX_DEVS);
 775         class_destroy(mei_class);
 776         mei_cl_bus_exit();
 777 }
 778
 779 module_init(mei_init);
 780 module_exit(mei_exit);
 781
 782 MODULE_AUTHOR("Intel Corporation");
 783 MODULE_DESCRIPTION("Intel(R) Management Engine Interface");
 784 MODULE_LICENSE("GPL v2");
 785