xref: /openbmc/linux/drivers/misc/mei/main.c (revision 275876e2)
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/fs.h>
21 #include <linux/errno.h>
22 #include <linux/types.h>
23 #include <linux/fcntl.h>
24 #include <linux/aio.h>
25 #include <linux/pci.h>
26 #include <linux/poll.h>
27 #include <linux/init.h>
28 #include <linux/ioctl.h>
29 #include <linux/cdev.h>
30 #include <linux/sched.h>
31 #include <linux/uuid.h>
32 #include <linux/compat.h>
33 #include <linux/jiffies.h>
34 #include <linux/interrupt.h>
35 
36 #include <linux/mei.h>
37 
38 #include "mei_dev.h"
39 #include "client.h"
40 
41 /**
42  * mei_open - the open function
43  *
44  * @inode: pointer to inode structure
45  * @file: pointer to file structure
46  *
47  * returns 0 on success, <0 on error
48  */
49 static int mei_open(struct inode *inode, struct file *file)
50 {
51 	struct mei_device *dev;
52 	struct mei_cl *cl;
53 
54 	int err;
55 
56 	dev = container_of(inode->i_cdev, struct mei_device, cdev);
57 	if (!dev)
58 		return -ENODEV;
59 
60 	mutex_lock(&dev->device_lock);
61 
62 	cl = NULL;
63 
64 	err = -ENODEV;
65 	if (dev->dev_state != MEI_DEV_ENABLED) {
66 		dev_dbg(&dev->pdev->dev, "dev_state != MEI_ENABLED  dev_state = %s\n",
67 		    mei_dev_state_str(dev->dev_state));
68 		goto err_unlock;
69 	}
70 
71 	err = -ENOMEM;
72 	cl = mei_cl_allocate(dev);
73 	if (!cl)
74 		goto err_unlock;
75 
76 	/* open_handle_count check is handled in the mei_cl_link */
77 	err = mei_cl_link(cl, MEI_HOST_CLIENT_ID_ANY);
78 	if (err)
79 		goto err_unlock;
80 
81 	file->private_data = cl;
82 
83 	mutex_unlock(&dev->device_lock);
84 
85 	return nonseekable_open(inode, file);
86 
87 err_unlock:
88 	mutex_unlock(&dev->device_lock);
89 	kfree(cl);
90 	return err;
91 }
92 
93 /**
94  * mei_release - the release function
95  *
96  * @inode: pointer to inode structure
97  * @file: pointer to file structure
98  *
99  * returns 0 on success, <0 on error
100  */
101 static int mei_release(struct inode *inode, struct file *file)
102 {
103 	struct mei_cl *cl = file->private_data;
104 	struct mei_cl_cb *cb;
105 	struct mei_device *dev;
106 	int rets = 0;
107 
108 	if (WARN_ON(!cl || !cl->dev))
109 		return -ENODEV;
110 
111 	dev = cl->dev;
112 
113 	mutex_lock(&dev->device_lock);
114 	if (cl == &dev->iamthif_cl) {
115 		rets = mei_amthif_release(dev, file);
116 		goto out;
117 	}
118 	if (cl->state == MEI_FILE_CONNECTED) {
119 		cl->state = MEI_FILE_DISCONNECTING;
120 		cl_dbg(dev, cl, "disconnecting\n");
121 		rets = mei_cl_disconnect(cl);
122 	}
123 	mei_cl_flush_queues(cl);
124 	cl_dbg(dev, cl, "removing\n");
125 
126 	mei_cl_unlink(cl);
127 
128 
129 	/* free read cb */
130 	cb = NULL;
131 	if (cl->read_cb) {
132 		cb = mei_cl_find_read_cb(cl);
133 		/* Remove entry from read list */
134 		if (cb)
135 			list_del(&cb->list);
136 
137 		cb = cl->read_cb;
138 		cl->read_cb = NULL;
139 	}
140 
141 	file->private_data = NULL;
142 
143 	mei_io_cb_free(cb);
144 
145 	kfree(cl);
146 out:
147 	mutex_unlock(&dev->device_lock);
148 	return rets;
149 }
150 
151 
152 /**
153  * mei_read - the read function.
154  *
155  * @file: pointer to file structure
156  * @ubuf: pointer to user buffer
157  * @length: buffer length
158  * @offset: data offset in buffer
159  *
160  * returns >=0 data length on success , <0 on error
161  */
162 static ssize_t mei_read(struct file *file, char __user *ubuf,
163 			size_t length, loff_t *offset)
164 {
165 	struct mei_cl *cl = file->private_data;
166 	struct mei_cl_cb *cb_pos = NULL;
167 	struct mei_cl_cb *cb = NULL;
168 	struct mei_device *dev;
169 	int rets;
170 	int err;
171 
172 
173 	if (WARN_ON(!cl || !cl->dev))
174 		return -ENODEV;
175 
176 	dev = cl->dev;
177 
178 
179 	mutex_lock(&dev->device_lock);
180 	if (dev->dev_state != MEI_DEV_ENABLED) {
181 		rets = -ENODEV;
182 		goto out;
183 	}
184 
185 	if (length == 0) {
186 		rets = 0;
187 		goto out;
188 	}
189 
190 	if (cl == &dev->iamthif_cl) {
191 		rets = mei_amthif_read(dev, file, ubuf, length, offset);
192 		goto out;
193 	}
194 
195 	if (cl->read_cb) {
196 		cb = cl->read_cb;
197 		/* read what left */
198 		if (cb->buf_idx > *offset)
199 			goto copy_buffer;
200 		/* offset is beyond buf_idx we have no more data return 0 */
201 		if (cb->buf_idx > 0 && cb->buf_idx <= *offset) {
202 			rets = 0;
203 			goto free;
204 		}
205 		/* Offset needs to be cleaned for contiguous reads*/
206 		if (cb->buf_idx == 0 && *offset > 0)
207 			*offset = 0;
208 	} else if (*offset > 0) {
209 		*offset = 0;
210 	}
211 
212 	err = mei_cl_read_start(cl, length);
213 	if (err && err != -EBUSY) {
214 		dev_dbg(&dev->pdev->dev,
215 			"mei start read failure with status = %d\n", err);
216 		rets = err;
217 		goto out;
218 	}
219 
220 	if (MEI_READ_COMPLETE != cl->reading_state &&
221 			!waitqueue_active(&cl->rx_wait)) {
222 		if (file->f_flags & O_NONBLOCK) {
223 			rets = -EAGAIN;
224 			goto out;
225 		}
226 
227 		mutex_unlock(&dev->device_lock);
228 
229 		if (wait_event_interruptible(cl->rx_wait,
230 				MEI_READ_COMPLETE == cl->reading_state ||
231 				mei_cl_is_transitioning(cl))) {
232 
233 			if (signal_pending(current))
234 				return -EINTR;
235 			return -ERESTARTSYS;
236 		}
237 
238 		mutex_lock(&dev->device_lock);
239 		if (mei_cl_is_transitioning(cl)) {
240 			rets = -EBUSY;
241 			goto out;
242 		}
243 	}
244 
245 	cb = cl->read_cb;
246 
247 	if (!cb) {
248 		rets = -ENODEV;
249 		goto out;
250 	}
251 	if (cl->reading_state != MEI_READ_COMPLETE) {
252 		rets = 0;
253 		goto out;
254 	}
255 	/* now copy the data to user space */
256 copy_buffer:
257 	dev_dbg(&dev->pdev->dev, "buf.size = %d buf.idx= %ld\n",
258 	    cb->response_buffer.size, cb->buf_idx);
259 	if (length == 0 || ubuf == NULL || *offset > cb->buf_idx) {
260 		rets = -EMSGSIZE;
261 		goto free;
262 	}
263 
264 	/* length is being truncated to PAGE_SIZE,
265 	 * however buf_idx may point beyond that */
266 	length = min_t(size_t, length, cb->buf_idx - *offset);
267 
268 	if (copy_to_user(ubuf, cb->response_buffer.data + *offset, length)) {
269 		dev_dbg(&dev->pdev->dev, "failed to copy data to userland\n");
270 		rets = -EFAULT;
271 		goto free;
272 	}
273 
274 	rets = length;
275 	*offset += length;
276 	if ((unsigned long)*offset < cb->buf_idx)
277 		goto out;
278 
279 free:
280 	cb_pos = mei_cl_find_read_cb(cl);
281 	/* Remove entry from read list */
282 	if (cb_pos)
283 		list_del(&cb_pos->list);
284 	mei_io_cb_free(cb);
285 	cl->reading_state = MEI_IDLE;
286 	cl->read_cb = NULL;
287 out:
288 	dev_dbg(&dev->pdev->dev, "end mei read rets= %d\n", rets);
289 	mutex_unlock(&dev->device_lock);
290 	return rets;
291 }
292 /**
293  * mei_write - the write function.
294  *
295  * @file: pointer to file structure
296  * @ubuf: pointer to user buffer
297  * @length: buffer length
298  * @offset: data offset in buffer
299  *
300  * returns >=0 data length on success , <0 on error
301  */
302 static ssize_t mei_write(struct file *file, const char __user *ubuf,
303 			 size_t length, loff_t *offset)
304 {
305 	struct mei_cl *cl = file->private_data;
306 	struct mei_cl_cb *write_cb = NULL;
307 	struct mei_device *dev;
308 	unsigned long timeout = 0;
309 	int rets;
310 	int id;
311 
312 	if (WARN_ON(!cl || !cl->dev))
313 		return -ENODEV;
314 
315 	dev = cl->dev;
316 
317 	mutex_lock(&dev->device_lock);
318 
319 	if (dev->dev_state != MEI_DEV_ENABLED) {
320 		rets = -ENODEV;
321 		goto out;
322 	}
323 
324 	id = mei_me_cl_by_id(dev, cl->me_client_id);
325 	if (id < 0) {
326 		rets = -ENOTTY;
327 		goto out;
328 	}
329 
330 	if (length == 0) {
331 		rets = 0;
332 		goto out;
333 	}
334 
335 	if (length > dev->me_clients[id].props.max_msg_length) {
336 		rets = -EFBIG;
337 		goto out;
338 	}
339 
340 	if (cl->state != MEI_FILE_CONNECTED) {
341 		dev_err(&dev->pdev->dev, "host client = %d,  is not connected to ME client = %d",
342 			cl->host_client_id, cl->me_client_id);
343 		rets = -ENODEV;
344 		goto out;
345 	}
346 	if (cl == &dev->iamthif_cl) {
347 		write_cb = mei_amthif_find_read_list_entry(dev, file);
348 
349 		if (write_cb) {
350 			timeout = write_cb->read_time +
351 				mei_secs_to_jiffies(MEI_IAMTHIF_READ_TIMER);
352 
353 			if (time_after(jiffies, timeout) ||
354 			    cl->reading_state == MEI_READ_COMPLETE) {
355 				*offset = 0;
356 				list_del(&write_cb->list);
357 				mei_io_cb_free(write_cb);
358 				write_cb = NULL;
359 			}
360 		}
361 	}
362 
363 	/* free entry used in read */
364 	if (cl->reading_state == MEI_READ_COMPLETE) {
365 		*offset = 0;
366 		write_cb = mei_cl_find_read_cb(cl);
367 		if (write_cb) {
368 			list_del(&write_cb->list);
369 			mei_io_cb_free(write_cb);
370 			write_cb = NULL;
371 			cl->reading_state = MEI_IDLE;
372 			cl->read_cb = NULL;
373 		}
374 	} else if (cl->reading_state == MEI_IDLE)
375 		*offset = 0;
376 
377 
378 	write_cb = mei_io_cb_init(cl, file);
379 	if (!write_cb) {
380 		dev_err(&dev->pdev->dev, "write cb allocation failed\n");
381 		rets = -ENOMEM;
382 		goto out;
383 	}
384 	rets = mei_io_cb_alloc_req_buf(write_cb, length);
385 	if (rets)
386 		goto out;
387 
388 	rets = copy_from_user(write_cb->request_buffer.data, ubuf, length);
389 	if (rets) {
390 		dev_dbg(&dev->pdev->dev, "failed to copy data from userland\n");
391 		rets = -EFAULT;
392 		goto out;
393 	}
394 
395 	if (cl == &dev->iamthif_cl) {
396 		rets = mei_amthif_write(dev, write_cb);
397 
398 		if (rets) {
399 			dev_err(&dev->pdev->dev,
400 				"amthif write failed with status = %d\n", rets);
401 			goto out;
402 		}
403 		mutex_unlock(&dev->device_lock);
404 		return length;
405 	}
406 
407 	rets = mei_cl_write(cl, write_cb, false);
408 out:
409 	mutex_unlock(&dev->device_lock);
410 	if (rets < 0)
411 		mei_io_cb_free(write_cb);
412 	return rets;
413 }
414 
415 /**
416  * mei_ioctl_connect_client - the connect to fw client IOCTL function
417  *
418  * @dev: the device structure
419  * @data: IOCTL connect data, input and output parameters
420  * @file: private data of the file object
421  *
422  * Locking: called under "dev->device_lock" lock
423  *
424  * returns 0 on success, <0 on failure.
425  */
426 static int mei_ioctl_connect_client(struct file *file,
427 			struct mei_connect_client_data *data)
428 {
429 	struct mei_device *dev;
430 	struct mei_client *client;
431 	struct mei_cl *cl;
432 	int i;
433 	int rets;
434 
435 	cl = file->private_data;
436 	if (WARN_ON(!cl || !cl->dev))
437 		return -ENODEV;
438 
439 	dev = cl->dev;
440 
441 	if (dev->dev_state != MEI_DEV_ENABLED) {
442 		rets = -ENODEV;
443 		goto end;
444 	}
445 
446 	if (cl->state != MEI_FILE_INITIALIZING &&
447 	    cl->state != MEI_FILE_DISCONNECTED) {
448 		rets = -EBUSY;
449 		goto end;
450 	}
451 
452 	/* find ME client we're trying to connect to */
453 	i = mei_me_cl_by_uuid(dev, &data->in_client_uuid);
454 	if (i < 0 || dev->me_clients[i].props.fixed_address) {
455 		dev_dbg(&dev->pdev->dev, "Cannot connect to FW Client UUID = %pUl\n",
456 				&data->in_client_uuid);
457 		rets = -ENOTTY;
458 		goto end;
459 	}
460 
461 	cl->me_client_id = dev->me_clients[i].client_id;
462 
463 	dev_dbg(&dev->pdev->dev, "Connect to FW Client ID = %d\n",
464 			cl->me_client_id);
465 	dev_dbg(&dev->pdev->dev, "FW Client - Protocol Version = %d\n",
466 			dev->me_clients[i].props.protocol_version);
467 	dev_dbg(&dev->pdev->dev, "FW Client - Max Msg Len = %d\n",
468 			dev->me_clients[i].props.max_msg_length);
469 
470 	/* if we're connecting to amthif client then we will use the
471 	 * existing connection
472 	 */
473 	if (uuid_le_cmp(data->in_client_uuid, mei_amthif_guid) == 0) {
474 		dev_dbg(&dev->pdev->dev, "FW Client is amthi\n");
475 		if (dev->iamthif_cl.state != MEI_FILE_CONNECTED) {
476 			rets = -ENODEV;
477 			goto end;
478 		}
479 		mei_cl_unlink(cl);
480 
481 		kfree(cl);
482 		cl = NULL;
483 		dev->iamthif_open_count++;
484 		file->private_data = &dev->iamthif_cl;
485 
486 		client = &data->out_client_properties;
487 		client->max_msg_length =
488 			dev->me_clients[i].props.max_msg_length;
489 		client->protocol_version =
490 			dev->me_clients[i].props.protocol_version;
491 		rets = dev->iamthif_cl.status;
492 
493 		goto end;
494 	}
495 
496 
497 	/* prepare the output buffer */
498 	client = &data->out_client_properties;
499 	client->max_msg_length = dev->me_clients[i].props.max_msg_length;
500 	client->protocol_version = dev->me_clients[i].props.protocol_version;
501 	dev_dbg(&dev->pdev->dev, "Can connect?\n");
502 
503 
504 	rets = mei_cl_connect(cl, file);
505 
506 end:
507 	return rets;
508 }
509 
510 
511 /**
512  * mei_ioctl - the IOCTL function
513  *
514  * @file: pointer to file structure
515  * @cmd: ioctl command
516  * @data: pointer to mei message structure
517  *
518  * returns 0 on success , <0 on error
519  */
520 static long mei_ioctl(struct file *file, unsigned int cmd, unsigned long data)
521 {
522 	struct mei_device *dev;
523 	struct mei_cl *cl = file->private_data;
524 	struct mei_connect_client_data *connect_data = NULL;
525 	int rets;
526 
527 	if (cmd != IOCTL_MEI_CONNECT_CLIENT)
528 		return -EINVAL;
529 
530 	if (WARN_ON(!cl || !cl->dev))
531 		return -ENODEV;
532 
533 	dev = cl->dev;
534 
535 	dev_dbg(&dev->pdev->dev, "IOCTL cmd = 0x%x", cmd);
536 
537 	mutex_lock(&dev->device_lock);
538 	if (dev->dev_state != MEI_DEV_ENABLED) {
539 		rets = -ENODEV;
540 		goto out;
541 	}
542 
543 	dev_dbg(&dev->pdev->dev, ": IOCTL_MEI_CONNECT_CLIENT.\n");
544 
545 	connect_data = kzalloc(sizeof(struct mei_connect_client_data),
546 							GFP_KERNEL);
547 	if (!connect_data) {
548 		rets = -ENOMEM;
549 		goto out;
550 	}
551 	dev_dbg(&dev->pdev->dev, "copy connect data from user\n");
552 	if (copy_from_user(connect_data, (char __user *)data,
553 				sizeof(struct mei_connect_client_data))) {
554 		dev_dbg(&dev->pdev->dev, "failed to copy data from userland\n");
555 		rets = -EFAULT;
556 		goto out;
557 	}
558 
559 	rets = mei_ioctl_connect_client(file, connect_data);
560 
561 	/* if all is ok, copying the data back to user. */
562 	if (rets)
563 		goto out;
564 
565 	dev_dbg(&dev->pdev->dev, "copy connect data to user\n");
566 	if (copy_to_user((char __user *)data, connect_data,
567 				sizeof(struct mei_connect_client_data))) {
568 		dev_dbg(&dev->pdev->dev, "failed to copy data to userland\n");
569 		rets = -EFAULT;
570 		goto out;
571 	}
572 
573 out:
574 	kfree(connect_data);
575 	mutex_unlock(&dev->device_lock);
576 	return rets;
577 }
578 
579 /**
580  * mei_compat_ioctl - the compat IOCTL function
581  *
582  * @file: pointer to file structure
583  * @cmd: ioctl command
584  * @data: pointer to mei message structure
585  *
586  * returns 0 on success , <0 on error
587  */
588 #ifdef CONFIG_COMPAT
589 static long mei_compat_ioctl(struct file *file,
590 			unsigned int cmd, unsigned long data)
591 {
592 	return mei_ioctl(file, cmd, (unsigned long)compat_ptr(data));
593 }
594 #endif
595 
596 
597 /**
598  * mei_poll - the poll function
599  *
600  * @file: pointer to file structure
601  * @wait: pointer to poll_table structure
602  *
603  * returns poll mask
604  */
605 static unsigned int mei_poll(struct file *file, poll_table *wait)
606 {
607 	struct mei_cl *cl = file->private_data;
608 	struct mei_device *dev;
609 	unsigned int mask = 0;
610 
611 	if (WARN_ON(!cl || !cl->dev))
612 		return POLLERR;
613 
614 	dev = cl->dev;
615 
616 	mutex_lock(&dev->device_lock);
617 
618 	if (!mei_cl_is_connected(cl)) {
619 		mask = POLLERR;
620 		goto out;
621 	}
622 
623 	mutex_unlock(&dev->device_lock);
624 
625 
626 	if (cl == &dev->iamthif_cl)
627 		return mei_amthif_poll(dev, file, wait);
628 
629 	poll_wait(file, &cl->tx_wait, wait);
630 
631 	mutex_lock(&dev->device_lock);
632 
633 	if (!mei_cl_is_connected(cl)) {
634 		mask = POLLERR;
635 		goto out;
636 	}
637 
638 	mask |= (POLLIN | POLLRDNORM);
639 
640 out:
641 	mutex_unlock(&dev->device_lock);
642 	return mask;
643 }
644 
645 /*
646  * file operations structure will be used for mei char device.
647  */
648 static const struct file_operations mei_fops = {
649 	.owner = THIS_MODULE,
650 	.read = mei_read,
651 	.unlocked_ioctl = mei_ioctl,
652 #ifdef CONFIG_COMPAT
653 	.compat_ioctl = mei_compat_ioctl,
654 #endif
655 	.open = mei_open,
656 	.release = mei_release,
657 	.write = mei_write,
658 	.poll = mei_poll,
659 	.llseek = no_llseek
660 };
661 
662 static struct class *mei_class;
663 static dev_t mei_devt;
664 #define MEI_MAX_DEVS  MINORMASK
665 static DEFINE_MUTEX(mei_minor_lock);
666 static DEFINE_IDR(mei_idr);
667 
668 /**
669  * mei_minor_get - obtain next free device minor number
670  *
671  * @dev:  device pointer
672  *
673  * returns allocated minor, or -ENOSPC if no free minor left
674  */
675 static int mei_minor_get(struct mei_device *dev)
676 {
677 	int ret;
678 
679 	mutex_lock(&mei_minor_lock);
680 	ret = idr_alloc(&mei_idr, dev, 0, MEI_MAX_DEVS, GFP_KERNEL);
681 	if (ret >= 0)
682 		dev->minor = ret;
683 	else if (ret == -ENOSPC)
684 		dev_err(&dev->pdev->dev, "too many mei devices\n");
685 
686 	mutex_unlock(&mei_minor_lock);
687 	return ret;
688 }
689 
690 /**
691  * mei_minor_free - mark device minor number as free
692  *
693  * @dev:  device pointer
694  */
695 static void mei_minor_free(struct mei_device *dev)
696 {
697 	mutex_lock(&mei_minor_lock);
698 	idr_remove(&mei_idr, dev->minor);
699 	mutex_unlock(&mei_minor_lock);
700 }
701 
702 int mei_register(struct mei_device *dev, struct device *parent)
703 {
704 	struct device *clsdev; /* class device */
705 	int ret, devno;
706 
707 	ret = mei_minor_get(dev);
708 	if (ret < 0)
709 		return ret;
710 
711 	/* Fill in the data structures */
712 	devno = MKDEV(MAJOR(mei_devt), dev->minor);
713 	cdev_init(&dev->cdev, &mei_fops);
714 	dev->cdev.owner = mei_fops.owner;
715 
716 	/* Add the device */
717 	ret = cdev_add(&dev->cdev, devno, 1);
718 	if (ret) {
719 		dev_err(parent, "unable to add device %d:%d\n",
720 			MAJOR(mei_devt), dev->minor);
721 		goto err_dev_add;
722 	}
723 
724 	clsdev = device_create(mei_class, parent, devno,
725 			 NULL, "mei%d", dev->minor);
726 
727 	if (IS_ERR(clsdev)) {
728 		dev_err(parent, "unable to create device %d:%d\n",
729 			MAJOR(mei_devt), dev->minor);
730 		ret = PTR_ERR(clsdev);
731 		goto err_dev_create;
732 	}
733 
734 	ret = mei_dbgfs_register(dev, dev_name(clsdev));
735 	if (ret) {
736 		dev_err(clsdev, "cannot register debugfs ret = %d\n", ret);
737 		goto err_dev_dbgfs;
738 	}
739 
740 	return 0;
741 
742 err_dev_dbgfs:
743 	device_destroy(mei_class, devno);
744 err_dev_create:
745 	cdev_del(&dev->cdev);
746 err_dev_add:
747 	mei_minor_free(dev);
748 	return ret;
749 }
750 EXPORT_SYMBOL_GPL(mei_register);
751 
752 void mei_deregister(struct mei_device *dev)
753 {
754 	int devno;
755 
756 	devno = dev->cdev.dev;
757 	cdev_del(&dev->cdev);
758 
759 	mei_dbgfs_deregister(dev);
760 
761 	device_destroy(mei_class, devno);
762 
763 	mei_minor_free(dev);
764 }
765 EXPORT_SYMBOL_GPL(mei_deregister);
766 
767 static int __init mei_init(void)
768 {
769 	int ret;
770 
771 	mei_class = class_create(THIS_MODULE, "mei");
772 	if (IS_ERR(mei_class)) {
773 		pr_err("couldn't create class\n");
774 		ret = PTR_ERR(mei_class);
775 		goto err;
776 	}
777 
778 	ret = alloc_chrdev_region(&mei_devt, 0, MEI_MAX_DEVS, "mei");
779 	if (ret < 0) {
780 		pr_err("unable to allocate char dev region\n");
781 		goto err_class;
782 	}
783 
784 	ret = mei_cl_bus_init();
785 	if (ret < 0) {
786 		pr_err("unable to initialize bus\n");
787 		goto err_chrdev;
788 	}
789 
790 	return 0;
791 
792 err_chrdev:
793 	unregister_chrdev_region(mei_devt, MEI_MAX_DEVS);
794 err_class:
795 	class_destroy(mei_class);
796 err:
797 	return ret;
798 }
799 
800 static void __exit mei_exit(void)
801 {
802 	unregister_chrdev_region(mei_devt, MEI_MAX_DEVS);
803 	class_destroy(mei_class);
804 	mei_cl_bus_exit();
805 }
806 
807 module_init(mei_init);
808 module_exit(mei_exit);
809 
810 MODULE_AUTHOR("Intel Corporation");
811 MODULE_DESCRIPTION("Intel(R) Management Engine Interface");
812 MODULE_LICENSE("GPL v2");
813 
814