aboutsummaryrefslogtreecommitdiff
path: root/drivers/misc/mei/main.c
blob: 80f9afcb13823282a9859e08a96c36f55901efa6 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
/*
 *
 * Intel Management Engine Interface (Intel MEI) Linux driver
 * Copyright (c) 2003-2012, Intel Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 */
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/fcntl.h>
#include <linux/poll.h>
#include <linux/init.h>
#include <linux/ioctl.h>
#include <linux/cdev.h>
#include <linux/sched.h>
#include <linux/uuid.h>
#include <linux/compat.h>
#include <linux/jiffies.h>
#include <linux/interrupt.h>

#include <linux/mei.h>

#include "mei_dev.h"
#include "client.h"

/**
 * mei_open - the open function
 *
 * @inode: pointer to inode structure
 * @file: pointer to file structure
 *
 * Return: 0 on success, <0 on error
 */
static int mei_open(struct inode *inode, struct file *file)
{
	struct mei_device *dev;
	struct mei_cl *cl;

	int err;

	dev = container_of(inode->i_cdev, struct mei_device, cdev);
	if (!dev)
		return -ENODEV;

	mutex_lock(&dev->device_lock);

	if (dev->dev_state != MEI_DEV_ENABLED) {
		dev_dbg(dev->dev, "dev_state != MEI_ENABLED  dev_state = %s\n",
		    mei_dev_state_str(dev->dev_state));
		err = -ENODEV;
		goto err_unlock;
	}

	cl = mei_cl_alloc_linked(dev, MEI_HOST_CLIENT_ID_ANY);
	if (IS_ERR(cl)) {
		err = PTR_ERR(cl);
		goto err_unlock;
	}

	file->private_data = cl;

	mutex_unlock(&dev->device_lock);

	return nonseekable_open(inode, file);

err_unlock:
	mutex_unlock(&dev->device_lock);
	return err;
}

/**
 * mei_release - the release function
 *
 * @inode: pointer to inode structure
 * @file: pointer to file structure
 *
 * Return: 0 on success, <0 on error
 */
static int mei_release(struct inode *inode, struct file *file)
{
	struct mei_cl *cl = file->private_data;
	struct mei_device *dev;
	int rets;

	if (WARN_ON(!cl || !cl->dev))
		return -ENODEV;

	dev = cl->dev;

	mutex_lock(&dev->device_lock);
	if (cl == &dev->iamthif_cl) {
		rets = mei_amthif_release(dev, file);
		goto out;
	}
	rets = mei_cl_disconnect(cl);

	mei_cl_flush_queues(cl, file);
	cl_dbg(dev, cl, "removing\n");

	mei_cl_unlink(cl);

	file->private_data = NULL;

	kfree(cl);
out:
	mutex_unlock(&dev->device_lock);
	return rets;
}


/**
 * mei_read - the read function.
 *
 * @file: pointer to file structure
 * @ubuf: pointer to user buffer
 * @length: buffer length
 * @offset: data offset in buffer
 *
 * Return: >=0 data length on success , <0 on error
 */
static ssize_t mei_read(struct file *file, char __user *ubuf,
			size_t length, loff_t *offset)
{
	struct mei_cl *cl = file->private_data;
	struct mei_device *dev;
	struct mei_cl_cb *cb = NULL;
	int rets;
	int err;


	if (WARN_ON(!cl || !cl->dev))
		return -ENODEV;

	dev = cl->dev;


	mutex_lock(&dev->device_lock);
	if (dev->dev_state != MEI_DEV_ENABLED) {
		rets = -ENODEV;
		goto out;
	}

	if (length == 0) {
		rets = 0;
		goto out;
	}

	if (cl == &dev->iamthif_cl) {
		rets = mei_amthif_read(dev, file, ubuf, length, offset);
		goto out;
	}

	cb = mei_cl_read_cb(cl, file);
	if (cb) {
		/* read what left */
		if (cb->buf_idx > *offset)
			goto copy_buffer;
		/* offset is beyond buf_idx we have no more data return 0 */
		if (cb->buf_idx > 0 && cb->buf_idx <= *offset) {
			rets = 0;
			goto free;
		}
		/* Offset needs to be cleaned for contiguous reads*/
		if (cb->buf_idx == 0 && *offset > 0)
			*offset = 0;
	} else if (*offset > 0) {
		*offset = 0;
	}

	err = mei_cl_read_start(cl, length, file);
	if (err && err != -EBUSY) {
		cl_dbg(dev, cl, "mei start read failure status = %d\n", err);
		rets = err;
		goto out;
	}

	if (list_empty(&cl->rd_completed) && !waitqueue_active(&cl->rx_wait)) {
		if (file->f_flags & O_NONBLOCK) {
			rets = -EAGAIN;
			goto out;
		}

		mutex_unlock(&dev->device_lock);

		if (wait_event_interruptible(cl->rx_wait,
				(!list_empty(&cl->rd_completed)) ||
				(!mei_cl_is_connected(cl)))) {

			if (signal_pending(current))
				return -EINTR;
			return -ERESTARTSYS;
		}

		mutex_lock(&dev->device_lock);
		if (!mei_cl_is_connected(cl)) {
			rets = -EBUSY;
			goto out;
		}
	}

	cb = mei_cl_read_cb(cl, file);
	if (!cb) {
		if (mei_cl_is_fixed_address(cl) && dev->allow_fixed_address) {
			cb = mei_cl_read_cb(cl, NULL);
			if (cb)
				goto copy_buffer;
		}
		rets = 0;
		goto out;
	}

copy_buffer:
	/* now copy the data to user space */
	if (cb->status) {
		rets = cb->status;
		cl_dbg(dev, cl, "read operation failed %d\n", rets);
		goto free;
	}

	cl_dbg(dev, cl, "buf.size = %d buf.idx = %ld\n",
	    cb->buf.size, cb->buf_idx);
	if (length == 0 || ubuf == NULL || *offset > cb->buf_idx) {
		rets = -EMSGSIZE;
		goto free;
	}

	/* length is being truncated to PAGE_SIZE,
	 * however buf_idx may point beyond that */
	length = min_t(size_t, length, cb->buf_idx - *offset);

	if (copy_to_user(ubuf, cb->buf.data + *offset, length)) {
		dev_dbg(dev->dev, "failed to copy data to userland\n");
		rets = -EFAULT;
		goto free;
	}

	rets = length;
	*offset += length;
	if ((unsigned long)*offset < cb->buf_idx)
		goto out;

free:
	mei_io_cb_free(cb);

out:
	cl_dbg(dev, cl, "end mei read rets = %d\n", rets);
	mutex_unlock(&dev->device_lock);
	return rets;
}
/**
 * mei_write - the write function.
 *
 * @file: pointer to file structure
 * @ubuf: pointer to user buffer
 * @length: buffer length
 * @offset: data offset in buffer
 *
 * Return: >=0 data length on success , <0 on error
 */
static ssize_t mei_write(struct file *file, const char __user *ubuf,
			 size_t length, loff_t *offset)
{
	struct mei_cl *cl = file->private_data;
	struct mei_cl_cb *write_cb = NULL;
	struct mei_device *dev;
	unsigned long timeout = 0;
	int rets;

	if (WARN_ON(!cl || !cl->dev))
		return -ENODEV;

	dev = cl->dev;

	mutex_lock(&dev->device_lock);

	if (dev->dev_state != MEI_DEV_ENABLED) {
		rets = -ENODEV;
		goto out;
	}

	if (!mei_cl_is_connected(cl)) {
		cl_err(dev, cl, "is not connected");
		rets = -ENODEV;
		goto out;
	}

	if (!mei_me_cl_is_active(cl->me_cl)) {
		rets = -ENOTTY;
		goto out;
	}

	if (length > mei_cl_mtu(cl)) {
		rets = -EFBIG;
		goto out;
	}

	if (length == 0) {
		rets = 0;
		goto out;
	}

	if (cl == &dev->iamthif_cl) {
		write_cb = mei_amthif_find_read_list_entry(dev, file);

		if (write_cb) {
			timeout = write_cb->read_time +
				mei_secs_to_jiffies(MEI_IAMTHIF_READ_TIMER);

			if (time_after(jiffies, timeout)) {
				*offset = 0;
				mei_io_cb_free(write_cb);
				write_cb = NULL;
			}
		}
	}

	*offset = 0;
	write_cb = mei_cl_alloc_cb(cl, length, MEI_FOP_WRITE, file);
	if (!write_cb) {
		rets = -ENOMEM;
		goto out;
	}

	rets = copy_from_user(write_cb->buf.data, ubuf, length);
	if (rets) {
		dev_dbg(dev->dev, "failed to copy data from userland\n");
		rets = -EFAULT;
		goto out;
	}

	if (cl == &dev->iamthif_cl) {
		rets = mei_amthif_write(cl, write_cb);

		if (rets) {
			dev_err(dev->dev,
				"amthif write failed with status = %d\n", rets);
			goto out;
		}
		mutex_unlock(&dev->device_lock);
		return length;
	}

	rets = mei_cl_write(cl, write_cb, false);
out:
	mutex_unlock(&dev->device_lock);
	if (rets < 0)
		mei_io_cb_free(write_cb);
	return rets;
}

/**
 * mei_ioctl_connect_client - the connect to fw client IOCTL function
 *
 * @file: private data of the file object
 * @data: IOCTL connect data, input and output parameters
 *
 * Locking: called under "dev->device_lock" lock
 *
 * Return: 0 on success, <0 on failure.
 */
static int mei_ioctl_connect_client(struct file *file,
			struct mei_connect_client_data *data)
{
	struct mei_device *dev;
	struct mei_client *client;
	struct mei_me_client *me_cl;
	struct mei_cl *cl;
	int rets;

	cl = file->private_data;
	dev = cl->dev;

	if (dev->dev_state != MEI_DEV_ENABLED)
		return -ENODEV;

	if (cl->state != MEI_FILE_INITIALIZING &&
	    cl->state != MEI_FILE_DISCONNECTED)
		return  -EBUSY;

	/* find ME client we're trying to connect to */
	me_cl = mei_me_cl_by_uuid(dev, &data->in_client_uuid);
	if (!me_cl ||
	    (me_cl->props.fixed_address && !dev->allow_fixed_address)) {
		dev_dbg(dev->dev, "Cannot connect to FW Client UUID = %pUl\n",
			&data->in_client_uuid);
		mei_me_cl_put(me_cl);
		return  -ENOTTY;
	}

	dev_dbg(dev->dev, "Connect to FW Client ID = %d\n",
			me_cl->client_id);
	dev_dbg(dev->dev, "FW Client - Protocol Version = %d\n",
			me_cl->props.protocol_version);
	dev_dbg(dev->dev, "FW Client - Max Msg Len = %d\n",
			me_cl->props.max_msg_length);

	/* if we're connecting to amthif client then we will use the
	 * existing connection
	 */
	if (uuid_le_cmp(data->in_client_uuid, mei_amthif_guid) == 0) {
		dev_dbg(dev->dev, "FW Client is amthi\n");
		if (!mei_cl_is_connected(&dev->iamthif_cl)) {
			rets = -ENODEV;
			goto end;
		}
		mei_cl_unlink(cl);

		kfree(cl);
		cl = NULL;
		dev->iamthif_open_count++;
		file->private_data = &dev->iamthif_cl;

		client = &data->out_client_properties;
		client->max_msg_length = me_cl->props.max_msg_length;
		client->protocol_version = me_cl->props.protocol_version;
		rets = dev->iamthif_cl.status;

		goto end;
	}

	/* prepare the output buffer */
	client = &data->out_client_properties;
	client->max_msg_length = me_cl->props.max_msg_length;
	client->protocol_version = me_cl->props.protocol_version;
	dev_dbg(dev->dev, "Can connect?\n");

	rets = mei_cl_connect(cl, me_cl, file);

end:
	mei_me_cl_put(me_cl);
	return rets;
}

/**
 * mei_ioctl_client_notify_request -
 *     propagate event notification request to client
 *
 * @file: pointer to file structure
 * @request: 0 - disable, 1 - enable
 *
 * Return: 0 on success , <0 on error
 */
static int mei_ioctl_client_notify_request(struct file *file, u32 request)
{
	struct mei_cl *cl = file->private_data;

	if (request != MEI_HBM_NOTIFICATION_START &&
	    request != MEI_HBM_NOTIFICATION_STOP)
		return -EINVAL;

	return mei_cl_notify_request(cl, file, (u8)request);
}

/**
 * mei_ioctl_client_notify_get -  wait for notification request
 *
 * @file: pointer to file structure
 * @notify_get: 0 - disable, 1 - enable
 *
 * Return: 0 on success , <0 on error
 */
static int mei_ioctl_client_notify_get(struct file *file, u32 *notify_get)
{
	struct mei_cl *cl = file->private_data;
	bool notify_ev;
	bool block = (file->f_flags & O_NONBLOCK) == 0;
	int rets;

	rets = mei_cl_notify_get(cl, block, &notify_ev);
	if (rets)
		return rets;

	*notify_get = notify_ev ? 1 : 0;
	return 0;
}

/**
 * mei_ioctl - the IOCTL function
 *
 * @file: pointer to file structure
 * @cmd: ioctl command
 * @data: pointer to mei message structure
 *
 * Return: 0 on success , <0 on error
 */
static long mei_ioctl(struct file *file, unsigned int cmd, unsigned long data)
{
	struct mei_device *dev;
	struct mei_cl *cl = file->private_data;
	struct mei_connect_client_data connect_data;
	u32 notify_get, notify_req;
	int rets;


	if (WARN_ON(!cl || !cl->dev))
		return -ENODEV;

	dev = cl->dev;

	dev_dbg(dev->dev, "IOCTL cmd = 0x%x", cmd);

	mutex_lock(&dev->device_lock);
	if (dev->dev_state != MEI_DEV_ENABLED) {
		rets = -ENODEV;
		goto out;
	}

	switch (cmd) {
	case IOCTL_MEI_CONNECT_CLIENT:
		dev_dbg(dev->dev, ": IOCTL_MEI_CONNECT_CLIENT.\n");
		if (copy_from_user(&connect_data, (char __user *)data,
				sizeof(struct mei_connect_client_data))) {
			dev_dbg(dev->dev, "failed to copy data from userland\n");
			rets = -EFAULT;
			goto out;
		}

		rets = mei_ioctl_connect_client(file, &connect_data);
		if (rets)
			goto out;

		/* if all is ok, copying the data back to user. */
		if (copy_to_user((char __user *)data, &connect_data,
				sizeof(struct mei_connect_client_data))) {
			dev_dbg(dev->dev, "failed to copy data to userland\n");
			rets = -EFAULT;
			goto out;
		}

		break;

	case IOCTL_MEI_NOTIFY_SET:
		dev_dbg(dev->dev, ": IOCTL_MEI_NOTIFY_SET.\n");
		if (copy_from_user(&notify_req,
				   (char __user *)data, sizeof(notify_req))) {
			dev_dbg(dev->dev, "failed to copy data from userland\n");
			rets = -EFAULT;
			goto out;
		}
		rets = mei_ioctl_client_notify_request(file, notify_req);
		break;

	case IOCTL_MEI_NOTIFY_GET:
		dev_dbg(dev->dev, ": IOCTL_MEI_NOTIFY_GET.\n");
		rets = mei_ioctl_client_notify_get(file, &notify_get);
		if (rets)
			goto out;

		dev_dbg(dev->dev, "copy connect data to user\n");
		if (copy_to_user((char __user *)data,
				&notify_get, sizeof(notify_get))) {
			dev_dbg(dev->dev, "failed to copy data to userland\n");
			rets = -EFAULT;
			goto out;

		}
		break;

	default:
		dev_err(dev->dev, ": unsupported ioctl %d.\n", cmd);
		rets = -ENOIOCTLCMD;
	}

out:
	mutex_unlock(&dev->device_lock);
	return rets;
}

/**
 * mei_compat_ioctl - the compat IOCTL function
 *
 * @file: pointer to file structure
 * @cmd: ioctl command
 * @data: pointer to mei message structure
 *
 * Return: 0 on success , <0 on error
 */
#ifdef CONFIG_COMPAT
static long mei_compat_ioctl(struct file *file,
			unsigned int cmd, unsigned long data)
{
	return mei_ioctl(file, cmd, (unsigned long)compat_ptr(data));
}
#endif


/**
 * mei_poll - the poll function
 *
 * @file: pointer to file structure
 * @wait: pointer to poll_table structure
 *
 * Return: poll mask
 */
static unsigned int mei_poll(struct file *file, poll_table *wait)
{
	unsigned long req_events = poll_requested_events(wait);
	struct mei_cl *cl = file->private_data;
	struct mei_device *dev;
	unsigned int mask = 0;
	bool notify_en;

	if (WARN_ON(!cl || !cl->dev))
		return POLLERR;

	dev = cl->dev;

	mutex_lock(&dev->device_lock);

	notify_en = cl->notify_en && (req_events & POLLPRI);

	if (dev->dev_state != MEI_DEV_ENABLED ||
	    !mei_cl_is_connected(cl)) {
		mask = POLLERR;
		goto out;
	}

	if (cl == &dev->iamthif_cl) {
		mask = mei_amthif_poll(dev, file, wait);
		goto out;
	}

	if (notify_en) {
		poll_wait(file, &cl->ev_wait, wait);
		if (cl->notify_ev)
			mask |= POLLPRI;
	}

	if (req_events & (POLLIN | POLLRDNORM)) {
		poll_wait(file, &cl->rx_wait, wait);

		if (!list_empty(&cl->rd_completed))
			mask |= POLLIN | POLLRDNORM;
		else
			mei_cl_read_start(cl, 0, file);
	}

out:
	mutex_unlock(&dev->device_lock);
	return mask;
}

/**
 * mei_fasync - asynchronous io support
 *
 * @fd: file descriptor
 * @file: pointer to file structure
 * @band: band bitmap
 *
 * Return: negative on error,
 *         0 if it did no changes,
 *         and positive a process was added or deleted
 */
static int mei_fasync(int fd, struct file *file, int band)
{

	struct mei_cl *cl = file->private_data;

	if (!mei_cl_is_connected(cl))
		return -ENODEV;

	return fasync_helper(fd, file, band, &cl->ev_async);
}

/**
 * fw_status_show - mei device attribute show method
 *
 * @device: device pointer
 * @attr: attribute pointer
 * @buf:  char out buffer
 *
 * Return: number of the bytes printed into buf or error
 */
static ssize_t fw_status_show(struct device *device,
		struct device_attribute *attr, char *buf)
{
	struct mei_device *dev = dev_get_drvdata(device);
	struct mei_fw_status fw_status;
	int err, i;
	ssize_t cnt = 0;

	mutex_lock(&dev->device_lock);
	err = mei_fw_status(dev, &fw_status);
	mutex_unlock(&dev->device_lock);
	if (err) {
		dev_err(device, "read fw_status error = %d\n", err);
		return err;
	}

	for (i = 0; i < fw_status.count; i++)
		cnt += scnprintf(buf + cnt, PAGE_SIZE - cnt, "%08X\n",
				fw_status.status[i]);
	return cnt;
}
static DEVICE_ATTR_RO(fw_status);

static struct attribute *mei_attrs[] = {
	&dev_attr_fw_status.attr,
	NULL
};
ATTRIBUTE_GROUPS(mei);

/*
 * file operations structure will be used for mei char device.
 */
static const struct file_operations mei_fops = {
	.owner = THIS_MODULE,
	.read = mei_read,
	.unlocked_ioctl = mei_ioctl,
#ifdef CONFIG_COMPAT
	.compat_ioctl = mei_compat_ioctl,
#endif
	.open = mei_open,
	.release = mei_release,
	.write = mei_write,
	.poll = mei_poll,
	.fasync = mei_fasync,
	.llseek = no_llseek
};

static struct class *mei_class;
static dev_t mei_devt;
#define MEI_MAX_DEVS  MINORMASK
static DEFINE_MUTEX(mei_minor_lock);
static DEFINE_IDR(mei_idr);

/**
 * mei_minor_get - obtain next free device minor number
 *
 * @dev:  device pointer
 *
 * Return: allocated minor, or -ENOSPC if no free minor left
 */
static int mei_minor_get(struct mei_device *dev)
{
	int ret;

	mutex_lock(&mei_minor_lock);
	ret = idr_alloc(&mei_idr, dev, 0, MEI_MAX_DEVS, GFP_KERNEL);
	if (ret >= 0)
		dev->minor = ret;
	else if (ret == -ENOSPC)
		dev_err(dev->dev, "too many mei devices\n");

	mutex_unlock(&mei_minor_lock);
	return ret;
}

/**
 * mei_minor_free - mark device minor number as free
 *
 * @dev:  device pointer
 */
static void mei_minor_free(struct mei_device *dev)
{
	mutex_lock(&mei_minor_lock);
	idr_remove(&mei_idr, dev->minor);
	mutex_unlock(&mei_minor_lock);
}

int mei_register(struct mei_device *dev, struct device *parent)
{
	struct device *clsdev; /* class device */
	int ret, devno;

	ret = mei_minor_get(dev);
	if (ret < 0)
		return ret;

	/* Fill in the data structures */
	devno = MKDEV(MAJOR(mei_devt), dev->minor);
	cdev_init(&dev->cdev, &mei_fops);
	dev->cdev.owner = parent->driver->owner;

	/* Add the device */
	ret = cdev_add(&dev->cdev, devno, 1);
	if (ret) {
		dev_err(parent, "unable to add device %d:%d\n",
			MAJOR(mei_devt), dev->minor);
		goto err_dev_add;
	}

	clsdev = device_create_with_groups(mei_class, parent, devno,
					   dev, mei_groups,
					   "mei%d", dev->minor);

	if (IS_ERR(clsdev)) {
		dev_err(parent, "unable to create device %d:%d\n",
			MAJOR(mei_devt), dev->minor);
		ret = PTR_ERR(clsdev);
		goto err_dev_create;
	}

	ret = mei_dbgfs_register(dev, dev_name(clsdev));
	if (ret) {
		dev_err(clsdev, "cannot register debugfs ret = %d\n", ret);
		goto err_dev_dbgfs;
	}

	return 0;

err_dev_dbgfs:
	device_destroy(mei_class, devno);
err_dev_create:
	cdev_del(&dev->cdev);
err_dev_add:
	mei_minor_free(dev);
	return ret;
}
EXPORT_SYMBOL_GPL(mei_register);

void mei_deregister(struct mei_device *dev)
{
	int devno;

	devno = dev->cdev.dev;
	cdev_del(&dev->cdev);

	mei_dbgfs_deregister(dev);

	device_destroy(mei_class, devno);

	mei_minor_free(dev);
}
EXPORT_SYMBOL_GPL(mei_deregister);

static int __init mei_init(void)
{
	int ret;

	mei_class = class_create(THIS_MODULE, "mei");
	if (IS_ERR(mei_class)) {
		pr_err("couldn't create class\n");
		ret = PTR_ERR(mei_class);
		goto err;
	}

	ret = alloc_chrdev_region(&mei_devt, 0, MEI_MAX_DEVS, "mei");
	if (ret < 0) {
		pr_err("unable to allocate char dev region\n");
		goto err_class;
	}

	ret = mei_cl_bus_init();
	if (ret < 0) {
		pr_err("unable to initialize bus\n");
		goto err_chrdev;
	}

	return 0;

err_chrdev:
	unregister_chrdev_region(mei_devt, MEI_MAX_DEVS);
err_class:
	class_destroy(mei_class);
err:
	return ret;
}

static void __exit mei_exit(void)
{
	unregister_chrdev_region(mei_devt, MEI_MAX_DEVS);
	class_destroy(mei_class);
	mei_cl_bus_exit();
}

module_init(mei_init);
module_exit(mei_exit);

MODULE_AUTHOR("Intel Corporation");
MODULE_DESCRIPTION("Intel(R) Management Engine Interface");
MODULE_LICENSE("GPL v2");