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 = 0;
  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         if (mei_cl_is_connected(cl)) {
 110                 cl->state = MEI_FILE_DISCONNECTING;
 111                 cl_dbg(dev, cl, "disconnecting\n");
 112                 rets = mei_cl_disconnect(cl);
 113         }
 114         mei_cl_flush_queues(cl, file);
 115         cl_dbg(dev, cl, "removing\n");
 116
 117         mei_cl_unlink(cl);
 118
 119         file->private_data = NULL;
 120
 121         kfree(cl);
 122 out:
 123         mutex_unlock(&dev->device_lock);
 124         return rets;
 125 }
 126
 127
 128 /**
 129  * mei_read - the read function.
 130  *
 131  * @file: pointer to file structure
 132  * @ubuf: pointer to user buffer
 133  * @length: buffer length
 134  * @offset: data offset in buffer
 135  *
 136  * Return: >=0 data length on success , <0 on error
 137  */
 138 static ssize_t mei_read(struct file *file, char __user *ubuf,
 139                         size_t length, loff_t *offset)
 140 {
 141         struct mei_cl *cl = file->private_data;
 142         struct mei_device *dev;
 143         struct mei_cl_cb *cb = NULL;
 144         int rets;
 145         int err;
 146
 147
 148         if (WARN_ON(!cl || !cl->dev))
 149                 return -ENODEV;
 150
 151         dev = cl->dev;
 152
 153
 154         mutex_lock(&dev->device_lock);
 155         if (dev->dev_state != MEI_DEV_ENABLED) {
 156                 rets = -ENODEV;
 157                 goto out;
 158         }
 159
 160         if (length == 0) {
 161                 rets = 0;
 162                 goto out;
 163         }
 164
 165         if (cl == &dev->iamthif_cl) {
 166                 rets = mei_amthif_read(dev, file, ubuf, length, offset);
 167                 goto out;
 168         }
 169
 170         cb = mei_cl_read_cb(cl, file);
 171         if (cb) {
 172                 /* read what left */
 173                 if (cb->buf_idx > *offset)
 174                         goto copy_buffer;
 175                 /* offset is beyond buf_idx we have no more data return 0 */
 176                 if (cb->buf_idx > 0 && cb->buf_idx <= *offset) {
 177                         rets = 0;
 178                         goto free;
 179                 }
 180                 /* Offset needs to be cleaned for contiguous reads*/
 181                 if (cb->buf_idx == 0 && *offset > 0)
 182                         *offset = 0;
 183         } else if (*offset > 0) {
 184                 *offset = 0;
 185         }
 186
 187         err = mei_cl_read_start(cl, length, file);
 188         if (err && err != -EBUSY) {
 189                 dev_dbg(dev->dev,
 190                         "mei start read failure with status = %d\n", err);
 191                 rets = err;
 192                 goto out;
 193         }
 194
 195         if (list_empty(&cl->rd_completed) && !waitqueue_active(&cl->rx_wait)) {
 196                 if (file->f_flags & O_NONBLOCK) {
 197                         rets = -EAGAIN;
 198                         goto out;
 199                 }
 200
 201                 mutex_unlock(&dev->device_lock);
 202
 203                 if (wait_event_interruptible(cl->rx_wait,
 204                                 (!list_empty(&cl->rd_completed)) ||
 205                                 (!mei_cl_is_connected(cl)))) {
 206
 207                         if (signal_pending(current))
 208                                 return -EINTR;
 209                         return -ERESTARTSYS;
 210                 }
 211
 212                 mutex_lock(&dev->device_lock);
 213                 if (!mei_cl_is_connected(cl)) {
 214                         rets = -EBUSY;
 215                         goto out;
 216                 }
 217         }
 218
 219         cb = mei_cl_read_cb(cl, file);
 220         if (!cb) {
 221                 rets = 0;
 222                 goto out;
 223         }
 224
 225 copy_buffer:
 226         /* now copy the data to user space */
 227         if (cb->status) {
 228                 rets = cb->status;
 229                 dev_dbg(dev->dev, "read operation failed %d\n", rets);
 230                 goto free;
 231         }
 232
 233         dev_dbg(dev->dev, "buf.size = %d buf.idx= %ld\n",
 234             cb->buf.size, cb->buf_idx);
 235         if (length == 0 || ubuf == NULL || *offset > cb->buf_idx) {
 236                 rets = -EMSGSIZE;
 237                 goto free;
 238         }
 239
 240         /* length is being truncated to PAGE_SIZE,
 241          * however buf_idx may point beyond that */
 242         length = min_t(size_t, length, cb->buf_idx - *offset);
 243
 244         if (copy_to_user(ubuf, cb->buf.data + *offset, length)) {
 245                 dev_dbg(dev->dev, "failed to copy data to userland\n");
 246                 rets = -EFAULT;
 247                 goto free;
 248         }
 249
 250         rets = length;
 251         *offset += length;
 252         if ((unsigned long)*offset < cb->buf_idx)
 253                 goto out;
 254
 255 free:
 256         mei_io_cb_free(cb);
 257
 258 out:
 259         dev_dbg(dev->dev, "end mei read rets= %d\n", rets);
 260         mutex_unlock(&dev->device_lock);
 261         return rets;
 262 }
 263 /**
 264  * mei_write - the write function.
 265  *
 266  * @file: pointer to file structure
 267  * @ubuf: pointer to user buffer
 268  * @length: buffer length
 269  * @offset: data offset in buffer
 270  *
 271  * Return: >=0 data length on success , <0 on error
 272  */
 273 static ssize_t mei_write(struct file *file, const char __user *ubuf,
 274                          size_t length, loff_t *offset)
 275 {
 276         struct mei_cl *cl = file->private_data;
 277         struct mei_me_client *me_cl = NULL;
 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         me_cl = mei_me_cl_by_uuid_id(dev, &cl->cl_uuid, cl->me_client_id);
 296         if (!me_cl) {
 297                 rets = -ENOTTY;
 298                 goto out;
 299         }
 300
 301         if (length == 0) {
 302                 rets = 0;
 303                 goto out;
 304         }
 305
 306         if (length > me_cl->props.max_msg_length) {
 307                 rets = -EFBIG;
 308                 goto out;
 309         }
 310
 311         if (!mei_cl_is_connected(cl)) {
 312                 cl_err(dev, cl, "is not connected");
 313                 rets = -ENODEV;
 314                 goto out;
 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                 mei_me_cl_put(me_cl);
 354                 mutex_unlock(&dev->device_lock);
 355                 return length;
 356         }
 357
 358         rets = mei_cl_write(cl, write_cb, false);
 359 out:
 360         mei_me_cl_put(me_cl);
 361         mutex_unlock(&dev->device_lock);
 362         if (rets < 0)
 363                 mei_io_cb_free(write_cb);
 364         return rets;
 365 }
 366
 367 /**
 368  * mei_ioctl_connect_client - the connect to fw client IOCTL function
 369  *
 370  * @file: private data of the file object
 371  * @data: IOCTL connect data, input and output parameters
 372  *
 373  * Locking: called under "dev->device_lock" lock
 374  *
 375  * Return: 0 on success, <0 on failure.
 376  */
 377 static int mei_ioctl_connect_client(struct file *file,
 378                         struct mei_connect_client_data *data)
 379 {
 380         struct mei_device *dev;
 381         struct mei_client *client;
 382         struct mei_me_client *me_cl;
 383         struct mei_cl *cl;
 384         int rets;
 385
 386         cl = file->private_data;
 387         dev = cl->dev;
 388
 389         if (dev->dev_state != MEI_DEV_ENABLED)
 390                 return -ENODEV;
 391
 392         if (cl->state != MEI_FILE_INITIALIZING &&
 393             cl->state != MEI_FILE_DISCONNECTED)
 394                 return  -EBUSY;
 395
 396         /* find ME client we're trying to connect to */
 397         me_cl = mei_me_cl_by_uuid(dev, &data->in_client_uuid);
 398         if (!me_cl || me_cl->props.fixed_address) {
 399                 dev_dbg(dev->dev, "Cannot connect to FW Client UUID = %pUl\n",
 400                                 &data->in_client_uuid);
 401                 return  -ENOTTY;
 402         }
 403
 404         cl->me_client_id = me_cl->client_id;
 405         cl->cl_uuid = me_cl->props.protocol_name;
 406
 407         dev_dbg(dev->dev, "Connect to FW Client ID = %d\n",
 408                         cl->me_client_id);
 409         dev_dbg(dev->dev, "FW Client - Protocol Version = %d\n",
 410                         me_cl->props.protocol_version);
 411         dev_dbg(dev->dev, "FW Client - Max Msg Len = %d\n",
 412                         me_cl->props.max_msg_length);
 413
 414         /* if we're connecting to amthif client then we will use the
 415          * existing connection
 416          */
 417         if (uuid_le_cmp(data->in_client_uuid, mei_amthif_guid) == 0) {
 418                 dev_dbg(dev->dev, "FW Client is amthi\n");
 419                 if (!mei_cl_is_connected(&dev->iamthif_cl)) {
 420                         rets = -ENODEV;
 421                         goto end;
 422                 }
 423                 mei_cl_unlink(cl);
 424
 425                 kfree(cl);
 426                 cl = NULL;
 427                 dev->iamthif_open_count++;
 428                 file->private_data = &dev->iamthif_cl;
 429
 430                 client = &data->out_client_properties;
 431                 client->max_msg_length = me_cl->props.max_msg_length;
 432                 client->protocol_version = me_cl->props.protocol_version;
 433                 rets = dev->iamthif_cl.status;
 434
 435                 goto end;
 436         }
 437
 438         /* prepare the output buffer */
 439         client = &data->out_client_properties;
 440         client->max_msg_length = me_cl->props.max_msg_length;
 441         client->protocol_version = me_cl->props.protocol_version;
 442         dev_dbg(dev->dev, "Can connect?\n");
 443
 444         rets = mei_cl_connect(cl, file);
 445
 446 end:
 447         mei_me_cl_put(me_cl);
 448         return rets;
 449 }
 450
 451 /**
 452  * mei_ioctl - the IOCTL function
 453  *
 454  * @file: pointer to file structure
 455  * @cmd: ioctl command
 456  * @data: pointer to mei message structure
 457  *
 458  * Return: 0 on success , <0 on error
 459  */
 460 static long mei_ioctl(struct file *file, unsigned int cmd, unsigned long data)
 461 {
 462         struct mei_device *dev;
 463         struct mei_cl *cl = file->private_data;
 464         struct mei_connect_client_data connect_data;
 465         int rets;
 466
 467
 468         if (WARN_ON(!cl || !cl->dev))
 469                 return -ENODEV;
 470
 471         dev = cl->dev;
 472
 473         dev_dbg(dev->dev, "IOCTL cmd = 0x%x", cmd);
 474
 475         mutex_lock(&dev->device_lock);
 476         if (dev->dev_state != MEI_DEV_ENABLED) {
 477                 rets = -ENODEV;
 478                 goto out;
 479         }
 480
 481         switch (cmd) {
 482         case IOCTL_MEI_CONNECT_CLIENT:
 483                 dev_dbg(dev->dev, ": IOCTL_MEI_CONNECT_CLIENT.\n");
 484                 if (copy_from_user(&connect_data, (char __user *)data,
 485                                 sizeof(struct mei_connect_client_data))) {
 486                         dev_dbg(dev->dev, "failed to copy data from userland\n");
 487                         rets = -EFAULT;
 488                         goto out;
 489                 }
 490
 491                 rets = mei_ioctl_connect_client(file, &connect_data);
 492                 if (rets)
 493                         goto out;
 494
 495                 /* if all is ok, copying the data back to user. */
 496                 if (copy_to_user((char __user *)data, &connect_data,
 497                                 sizeof(struct mei_connect_client_data))) {
 498                         dev_dbg(dev->dev, "failed to copy data to userland\n");
 499                         rets = -EFAULT;
 500                         goto out;
 501                 }
 502
 503                 break;
 504
 505         default:
 506                 dev_err(dev->dev, ": unsupported ioctl %d.\n", cmd);
 507                 rets = -ENOIOCTLCMD;
 508         }
 509
 510 out:
 511         mutex_unlock(&dev->device_lock);
 512         return rets;
 513 }
 514
 515 /**
 516  * mei_compat_ioctl - the compat IOCTL function
 517  *
 518  * @file: pointer to file structure
 519  * @cmd: ioctl command
 520  * @data: pointer to mei message structure
 521  *
 522  * Return: 0 on success , <0 on error
 523  */
 524 #ifdef CONFIG_COMPAT
 525 static long mei_compat_ioctl(struct file *file,
 526                         unsigned int cmd, unsigned long data)
 527 {
 528         return mei_ioctl(file, cmd, (unsigned long)compat_ptr(data));
 529 }
 530 #endif
 531
 532
 533 /**
 534  * mei_poll - the poll function
 535  *
 536  * @file: pointer to file structure
 537  * @wait: pointer to poll_table structure
 538  *
 539  * Return: poll mask
 540  */
 541 static unsigned int mei_poll(struct file *file, poll_table *wait)
 542 {
 543         unsigned long req_events = poll_requested_events(wait);
 544         struct mei_cl *cl = file->private_data;
 545         struct mei_device *dev;
 546         unsigned int mask = 0;
 547
 548         if (WARN_ON(!cl || !cl->dev))
 549                 return POLLERR;
 550
 551         dev = cl->dev;
 552
 553         mutex_lock(&dev->device_lock);
 554
 555
 556         if (dev->dev_state != MEI_DEV_ENABLED ||
 557             !mei_cl_is_connected(cl)) {
 558                 mask = POLLERR;
 559                 goto out;
 560         }
 561
 562         if (cl == &dev->iamthif_cl) {
 563                 mask = mei_amthif_poll(dev, file, wait);
 564                 goto out;
 565         }
 566
 567         if (req_events & (POLLIN | POLLRDNORM)) {
 568                 poll_wait(file, &cl->rx_wait, wait);
 569
 570                 if (!list_empty(&cl->rd_completed))
 571                         mask |= POLLIN | POLLRDNORM;
 572                 else
 573                         mei_cl_read_start(cl, 0, file);
 574         }
 575
 576 out:
 577         mutex_unlock(&dev->device_lock);
 578         return mask;
 579 }
 580
 581 /**
 582  * fw_status_show - mei device attribute show method
 583  *
 584  * @device: device pointer
 585  * @attr: attribute pointer
 586  * @buf:  char out buffer
 587  *
 588  * Return: number of the bytes printed into buf or error
 589  */
 590 static ssize_t fw_status_show(struct device *device,
 591                 struct device_attribute *attr, char *buf)
 592 {
 593         struct mei_device *dev = dev_get_drvdata(device);
 594         struct mei_fw_status fw_status;
 595         int err, i;
 596         ssize_t cnt = 0;
 597
 598         mutex_lock(&dev->device_lock);
 599         err = mei_fw_status(dev, &fw_status);
 600         mutex_unlock(&dev->device_lock);
 601         if (err) {
 602                 dev_err(device, "read fw_status error = %d\n", err);
 603                 return err;
 604         }
 605
 606         for (i = 0; i < fw_status.count; i++)
 607                 cnt += scnprintf(buf + cnt, PAGE_SIZE - cnt, "%08X\n",
 608                                 fw_status.status[i]);
 609         return cnt;
 610 }
 611 static DEVICE_ATTR_RO(fw_status);
 612
 613 static struct attribute *mei_attrs[] = {
 614         &dev_attr_fw_status.attr,
 615         NULL
 616 };
 617 ATTRIBUTE_GROUPS(mei);
 618
 619 /*
 620  * file operations structure will be used for mei char device.
 621  */
 622 static const struct file_operations mei_fops = {
 623         .owner = THIS_MODULE,
 624         .read = mei_read,
 625         .unlocked_ioctl = mei_ioctl,
 626 #ifdef CONFIG_COMPAT
 627         .compat_ioctl = mei_compat_ioctl,
 628 #endif
 629         .open = mei_open,
 630         .release = mei_release,
 631         .write = mei_write,
 632         .poll = mei_poll,
 633         .llseek = no_llseek
 634 };
 635
 636 static struct class *mei_class;
 637 static dev_t mei_devt;
 638 #define MEI_MAX_DEVS  MINORMASK
 639 static DEFINE_MUTEX(mei_minor_lock);
 640 static DEFINE_IDR(mei_idr);
 641
 642 /**
 643  * mei_minor_get - obtain next free device minor number
 644  *
 645  * @dev:  device pointer
 646  *
 647  * Return: allocated minor, or -ENOSPC if no free minor left
 648  */
 649 static int mei_minor_get(struct mei_device *dev)
 650 {
 651         int ret;
 652
 653         mutex_lock(&mei_minor_lock);
 654         ret = idr_alloc(&mei_idr, dev, 0, MEI_MAX_DEVS, GFP_KERNEL);
 655         if (ret >= 0)
 656                 dev->minor = ret;
 657         else if (ret == -ENOSPC)
 658                 dev_err(dev->dev, "too many mei devices\n");
 659
 660         mutex_unlock(&mei_minor_lock);
 661         return ret;
 662 }
 663
 664 /**
 665  * mei_minor_free - mark device minor number as free
 666  *
 667  * @dev:  device pointer
 668  */
 669 static void mei_minor_free(struct mei_device *dev)
 670 {
 671         mutex_lock(&mei_minor_lock);
 672         idr_remove(&mei_idr, dev->minor);
 673         mutex_unlock(&mei_minor_lock);
 674 }
 675
 676 int mei_register(struct mei_device *dev, struct device *parent)
 677 {
 678         struct device *clsdev; /* class device */
 679         int ret, devno;
 680
 681         ret = mei_minor_get(dev);
 682         if (ret < 0)
 683                 return ret;
 684
 685         /* Fill in the data structures */
 686         devno = MKDEV(MAJOR(mei_devt), dev->minor);
 687         cdev_init(&dev->cdev, &mei_fops);
 688         dev->cdev.owner = parent->driver->owner;
 689
 690         /* Add the device */
 691         ret = cdev_add(&dev->cdev, devno, 1);
 692         if (ret) {
 693                 dev_err(parent, "unable to add device %d:%d\n",
 694                         MAJOR(mei_devt), dev->minor);
 695                 goto err_dev_add;
 696         }
 697
 698         clsdev = device_create_with_groups(mei_class, parent, devno,
 699                                            dev, mei_groups,
 700                                            "mei%d", dev->minor);
 701
 702         if (IS_ERR(clsdev)) {
 703                 dev_err(parent, "unable to create device %d:%d\n",
 704                         MAJOR(mei_devt), dev->minor);
 705                 ret = PTR_ERR(clsdev);
 706                 goto err_dev_create;
 707         }
 708
 709         ret = mei_dbgfs_register(dev, dev_name(clsdev));
 710         if (ret) {
 711                 dev_err(clsdev, "cannot register debugfs ret = %d\n", ret);
 712                 goto err_dev_dbgfs;
 713         }
 714
 715         return 0;
 716
 717 err_dev_dbgfs:
 718         device_destroy(mei_class, devno);
 719 err_dev_create:
 720         cdev_del(&dev->cdev);
 721 err_dev_add:
 722         mei_minor_free(dev);
 723         return ret;
 724 }
 725 EXPORT_SYMBOL_GPL(mei_register);
 726
 727 void mei_deregister(struct mei_device *dev)
 728 {
 729         int devno;
 730
 731         devno = dev->cdev.dev;
 732         cdev_del(&dev->cdev);
 733
 734         mei_dbgfs_deregister(dev);
 735
 736         device_destroy(mei_class, devno);
 737
 738         mei_minor_free(dev);
 739 }
 740 EXPORT_SYMBOL_GPL(mei_deregister);
 741
 742 static int __init mei_init(void)
 743 {
 744         int ret;
 745
 746         mei_class = class_create(THIS_MODULE, "mei");
 747         if (IS_ERR(mei_class)) {
 748                 pr_err("couldn't create class\n");
 749                 ret = PTR_ERR(mei_class);
 750                 goto err;
 751         }
 752
 753         ret = alloc_chrdev_region(&mei_devt, 0, MEI_MAX_DEVS, "mei");
 754         if (ret < 0) {
 755                 pr_err("unable to allocate char dev region\n");
 756                 goto err_class;
 757         }
 758
 759         ret = mei_cl_bus_init();
 760         if (ret < 0) {
 761                 pr_err("unable to initialize bus\n");
 762                 goto err_chrdev;
 763         }
 764
 765         return 0;
 766
 767 err_chrdev:
 768         unregister_chrdev_region(mei_devt, MEI_MAX_DEVS);
 769 err_class:
 770         class_destroy(mei_class);
 771 err:
 772         return ret;
 773 }
 774
 775 static void __exit mei_exit(void)
 776 {
 777         unregister_chrdev_region(mei_devt, MEI_MAX_DEVS);
 778         class_destroy(mei_class);
 779         mei_cl_bus_exit();
 780 }
 781
 782 module_init(mei_init);
 783 module_exit(mei_exit);
 784
 785 MODULE_AUTHOR("Intel Corporation");
 786 MODULE_DESCRIPTION("Intel(R) Management Engine Interface");
 787 MODULE_LICENSE("GPL v2");
 788