aboutsummaryrefslogtreecommitdiff
path: root/drivers/gpu/drm/drm_stub.c
blob: 3727ac8bc310156b0cbf40563ef80392caf4addd (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
/**
 * \file drm_stub.h
 * Stub support
 *
 * \author Rickard E. (Rik) Faith <faith@valinux.com>
 */

/*
 * Created: Fri Jan 19 10:48:35 2001 by faith@acm.org
 *
 * Copyright 2001 VA Linux Systems, Inc., Sunnyvale, California.
 * All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * PRECISION INSIGHT AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */

#include <linux/fs.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/mount.h>
#include <linux/slab.h>
#include <drm/drmP.h>
#include <drm/drm_core.h>

unsigned int drm_debug = 0;	/* 1 to enable debug output */
EXPORT_SYMBOL(drm_debug);

unsigned int drm_rnodes = 0;	/* 1 to enable experimental render nodes API */
EXPORT_SYMBOL(drm_rnodes);

/* 1 to allow user space to request universal planes (experimental) */
unsigned int drm_universal_planes = 0;
EXPORT_SYMBOL(drm_universal_planes);

unsigned int drm_vblank_offdelay = 5000;    /* Default to 5000 msecs. */
EXPORT_SYMBOL(drm_vblank_offdelay);

unsigned int drm_timestamp_precision = 20;  /* Default to 20 usecs. */
EXPORT_SYMBOL(drm_timestamp_precision);

/*
 * Default to use monotonic timestamps for wait-for-vblank and page-flip
 * complete events.
 */
unsigned int drm_timestamp_monotonic = 1;

MODULE_AUTHOR(CORE_AUTHOR);
MODULE_DESCRIPTION(CORE_DESC);
MODULE_LICENSE("GPL and additional rights");
MODULE_PARM_DESC(debug, "Enable debug output");
MODULE_PARM_DESC(rnodes, "Enable experimental render nodes API");
MODULE_PARM_DESC(vblankoffdelay, "Delay until vblank irq auto-disable [msecs]");
MODULE_PARM_DESC(timestamp_precision_usec, "Max. error on timestamps [usecs]");
MODULE_PARM_DESC(timestamp_monotonic, "Use monotonic timestamps");

module_param_named(debug, drm_debug, int, 0600);
module_param_named(rnodes, drm_rnodes, int, 0600);
module_param_named(universal_planes, drm_universal_planes, int, 0600);
module_param_named(vblankoffdelay, drm_vblank_offdelay, int, 0600);
module_param_named(timestamp_precision_usec, drm_timestamp_precision, int, 0600);
module_param_named(timestamp_monotonic, drm_timestamp_monotonic, int, 0600);

static DEFINE_SPINLOCK(drm_minor_lock);
struct idr drm_minors_idr;

struct class *drm_class;
struct dentry *drm_debugfs_root;

int drm_err(const char *func, const char *format, ...)
{
	struct va_format vaf;
	va_list args;
	int r;

	va_start(args, format);

	vaf.fmt = format;
	vaf.va = &args;

	r = printk(KERN_ERR "[" DRM_NAME ":%s] *ERROR* %pV", func, &vaf);

	va_end(args);

	return r;
}
EXPORT_SYMBOL(drm_err);

void drm_ut_debug_printk(const char *function_name, const char *format, ...)
{
	struct va_format vaf;
	va_list args;

	va_start(args, format);
	vaf.fmt = format;
	vaf.va = &args;

	printk(KERN_DEBUG "[" DRM_NAME ":%s] %pV", function_name, &vaf);

	va_end(args);
}
EXPORT_SYMBOL(drm_ut_debug_printk);

struct drm_master *drm_master_create(struct drm_minor *minor)
{
	struct drm_master *master;

	master = kzalloc(sizeof(*master), GFP_KERNEL);
	if (!master)
		return NULL;

	kref_init(&master->refcount);
	spin_lock_init(&master->lock.spinlock);
	init_waitqueue_head(&master->lock.lock_queue);
	if (drm_ht_create(&master->magiclist, DRM_MAGIC_HASH_ORDER)) {
		kfree(master);
		return NULL;
	}
	INIT_LIST_HEAD(&master->magicfree);
	master->minor = minor;

	return master;
}

struct drm_master *drm_master_get(struct drm_master *master)
{
	kref_get(&master->refcount);
	return master;
}
EXPORT_SYMBOL(drm_master_get);

static void drm_master_destroy(struct kref *kref)
{
	struct drm_master *master = container_of(kref, struct drm_master, refcount);
	struct drm_magic_entry *pt, *next;
	struct drm_device *dev = master->minor->dev;
	struct drm_map_list *r_list, *list_temp;

	mutex_lock(&dev->struct_mutex);
	if (dev->driver->master_destroy)
		dev->driver->master_destroy(dev, master);

	list_for_each_entry_safe(r_list, list_temp, &dev->maplist, head) {
		if (r_list->master == master) {
			drm_rmmap_locked(dev, r_list->map);
			r_list = NULL;
		}
	}

	if (master->unique) {
		kfree(master->unique);
		master->unique = NULL;
		master->unique_len = 0;
	}

	list_for_each_entry_safe(pt, next, &master->magicfree, head) {
		list_del(&pt->head);
		drm_ht_remove_item(&master->magiclist, &pt->hash_item);
		kfree(pt);
	}

	drm_ht_remove(&master->magiclist);

	mutex_unlock(&dev->struct_mutex);
	kfree(master);
}

void drm_master_put(struct drm_master **master)
{
	kref_put(&(*master)->refcount, drm_master_destroy);
	*master = NULL;
}
EXPORT_SYMBOL(drm_master_put);

int drm_setmaster_ioctl(struct drm_device *dev, void *data,
			struct drm_file *file_priv)
{
	int ret = 0;

	mutex_lock(&dev->master_mutex);
	if (file_priv->is_master)
		goto out_unlock;

	if (file_priv->minor->master) {
		ret = -EINVAL;
		goto out_unlock;
	}

	if (!file_priv->master) {
		ret = -EINVAL;
		goto out_unlock;
	}

	file_priv->minor->master = drm_master_get(file_priv->master);
	file_priv->is_master = 1;
	if (dev->driver->master_set) {
		ret = dev->driver->master_set(dev, file_priv, false);
		if (unlikely(ret != 0)) {
			file_priv->is_master = 0;
			drm_master_put(&file_priv->minor->master);
		}
	}

out_unlock:
	mutex_unlock(&dev->master_mutex);
	return ret;
}

int drm_dropmaster_ioctl(struct drm_device *dev, void *data,
			 struct drm_file *file_priv)
{
	int ret = -EINVAL;

	mutex_lock(&dev->master_mutex);
	if (!file_priv->is_master)
		goto out_unlock;

	if (!file_priv->minor->master)
		goto out_unlock;

	ret = 0;
	if (dev->driver->master_drop)
		dev->driver->master_drop(dev, file_priv, false);
	drm_master_put(&file_priv->minor->master);
	file_priv->is_master = 0;

out_unlock:
	mutex_unlock(&dev->master_mutex);
	return ret;
}

/*
 * DRM Minors
 * A DRM device can provide several char-dev interfaces on the DRM-Major. Each
 * of them is represented by a drm_minor object. Depending on the capabilities
 * of the device-driver, different interfaces are registered.
 *
 * Minors can be accessed via dev->$minor_name. This pointer is either
 * NULL or a valid drm_minor pointer and stays valid as long as the device is
 * valid. This means, DRM minors have the same life-time as the underlying
 * device. However, this doesn't mean that the minor is active. Minors are
 * registered and unregistered dynamically according to device-state.
 */

static struct drm_minor **drm_minor_get_slot(struct drm_device *dev,
					     unsigned int type)
{
	switch (type) {
	case DRM_MINOR_LEGACY:
		return &dev->primary;
	case DRM_MINOR_RENDER:
		return &dev->render;
	case DRM_MINOR_CONTROL:
		return &dev->control;
	default:
		return NULL;
	}
}

static int drm_minor_alloc(struct drm_device *dev, unsigned int type)
{
	struct drm_minor *minor;

	minor = kzalloc(sizeof(*minor), GFP_KERNEL);
	if (!minor)
		return -ENOMEM;

	minor->type = type;
	minor->dev = dev;

	*drm_minor_get_slot(dev, type) = minor;
	return 0;
}

static void drm_minor_free(struct drm_device *dev, unsigned int type)
{
	struct drm_minor **slot;

	slot = drm_minor_get_slot(dev, type);
	if (*slot) {
		drm_mode_group_destroy(&(*slot)->mode_group);
		kfree(*slot);
		*slot = NULL;
	}
}

static int drm_minor_register(struct drm_device *dev, unsigned int type)
{
	struct drm_minor *new_minor;
	unsigned long flags;
	int ret;
	int minor_id;

	DRM_DEBUG("\n");

	new_minor = *drm_minor_get_slot(dev, type);
	if (!new_minor)
		return 0;

	idr_preload(GFP_KERNEL);
	spin_lock_irqsave(&drm_minor_lock, flags);
	minor_id = idr_alloc(&drm_minors_idr,
			     NULL,
			     64 * type,
			     64 * (type + 1),
			     GFP_NOWAIT);
	spin_unlock_irqrestore(&drm_minor_lock, flags);
	idr_preload_end();

	if (minor_id < 0)
		return minor_id;

	new_minor->index = minor_id;

	ret = drm_debugfs_init(new_minor, minor_id, drm_debugfs_root);
	if (ret) {
		DRM_ERROR("DRM: Failed to initialize /sys/kernel/debug/dri.\n");
		goto err_id;
	}

	ret = drm_sysfs_device_add(new_minor);
	if (ret) {
		DRM_ERROR("DRM: Error sysfs_device_add.\n");
		goto err_debugfs;
	}

	/* replace NULL with @minor so lookups will succeed from now on */
	spin_lock_irqsave(&drm_minor_lock, flags);
	idr_replace(&drm_minors_idr, new_minor, new_minor->index);
	spin_unlock_irqrestore(&drm_minor_lock, flags);

	DRM_DEBUG("new minor assigned %d\n", minor_id);
	return 0;

err_debugfs:
	drm_debugfs_cleanup(new_minor);
err_id:
	spin_lock_irqsave(&drm_minor_lock, flags);
	idr_remove(&drm_minors_idr, minor_id);
	spin_unlock_irqrestore(&drm_minor_lock, flags);
	new_minor->index = 0;
	return ret;
}

static void drm_minor_unregister(struct drm_device *dev, unsigned int type)
{
	struct drm_minor *minor;
	unsigned long flags;

	minor = *drm_minor_get_slot(dev, type);
	if (!minor || !minor->kdev)
		return;

	spin_lock_irqsave(&drm_minor_lock, flags);
	idr_remove(&drm_minors_idr, minor->index);
	spin_unlock_irqrestore(&drm_minor_lock, flags);
	minor->index = 0;

	drm_debugfs_cleanup(minor);
	drm_sysfs_device_remove(minor);
}

/**
 * drm_minor_acquire - Acquire a DRM minor
 * @minor_id: Minor ID of the DRM-minor
 *
 * Looks up the given minor-ID and returns the respective DRM-minor object. The
 * refence-count of the underlying device is increased so you must release this
 * object with drm_minor_release().
 *
 * As long as you hold this minor, it is guaranteed that the object and the
 * minor->dev pointer will stay valid! However, the device may get unplugged and
 * unregistered while you hold the minor.
 *
 * Returns:
 * Pointer to minor-object with increased device-refcount, or PTR_ERR on
 * failure.
 */
struct drm_minor *drm_minor_acquire(unsigned int minor_id)
{
	struct drm_minor *minor;
	unsigned long flags;

	spin_lock_irqsave(&drm_minor_lock, flags);
	minor = idr_find(&drm_minors_idr, minor_id);
	if (minor)
		drm_dev_ref(minor->dev);
	spin_unlock_irqrestore(&drm_minor_lock, flags);

	if (!minor) {
		return ERR_PTR(-ENODEV);
	} else if (drm_device_is_unplugged(minor->dev)) {
		drm_dev_unref(minor->dev);
		return ERR_PTR(-ENODEV);
	}

	return minor;
}

/**
 * drm_minor_release - Release DRM minor
 * @minor: Pointer to DRM minor object
 *
 * Release a minor that was previously acquired via drm_minor_acquire().
 */
void drm_minor_release(struct drm_minor *minor)
{
	drm_dev_unref(minor->dev);
}

/**
 * Called via drm_exit() at module unload time or when pci device is
 * unplugged.
 *
 * Cleans up all DRM device, calling drm_lastclose().
 *
 */
void drm_put_dev(struct drm_device *dev)
{
	DRM_DEBUG("\n");

	if (!dev) {
		DRM_ERROR("cleanup called no dev\n");
		return;
	}

	drm_dev_unregister(dev);
	drm_dev_unref(dev);
}
EXPORT_SYMBOL(drm_put_dev);

void drm_unplug_dev(struct drm_device *dev)
{
	/* for a USB device */
	drm_minor_unregister(dev, DRM_MINOR_LEGACY);
	drm_minor_unregister(dev, DRM_MINOR_RENDER);
	drm_minor_unregister(dev, DRM_MINOR_CONTROL);

	mutex_lock(&drm_global_mutex);

	drm_device_set_unplugged(dev);

	if (dev->open_count == 0) {
		drm_put_dev(dev);
	}
	mutex_unlock(&drm_global_mutex);
}
EXPORT_SYMBOL(drm_unplug_dev);

/*
 * DRM internal mount
 * We want to be able to allocate our own "struct address_space" to control
 * memory-mappings in VRAM (or stolen RAM, ...). However, core MM does not allow
 * stand-alone address_space objects, so we need an underlying inode. As there
 * is no way to allocate an independent inode easily, we need a fake internal
 * VFS mount-point.
 *
 * The drm_fs_inode_new() function allocates a new inode, drm_fs_inode_free()
 * frees it again. You are allowed to use iget() and iput() to get references to
 * the inode. But each drm_fs_inode_new() call must be paired with exactly one
 * drm_fs_inode_free() call (which does not have to be the last iput()).
 * We use drm_fs_inode_*() to manage our internal VFS mount-point and share it
 * between multiple inode-users. You could, technically, call
 * iget() + drm_fs_inode_free() directly after alloc and sometime later do an
 * iput(), but this way you'd end up with a new vfsmount for each inode.
 */

static int drm_fs_cnt;
static struct vfsmount *drm_fs_mnt;

static const struct dentry_operations drm_fs_dops = {
	.d_dname	= simple_dname,
};

static const struct super_operations drm_fs_sops = {
	.statfs		= simple_statfs,
};

static struct dentry *drm_fs_mount(struct file_system_type *fs_type, int flags,
				   const char *dev_name, void *data)
{
	return mount_pseudo(fs_type,
			    "drm:",
			    &drm_fs_sops,
			    &drm_fs_dops,
			    0x010203ff);
}

static struct file_system_type drm_fs_type = {
	.name		= "drm",
	.owner		= THIS_MODULE,
	.mount		= drm_fs_mount,
	.kill_sb	= kill_anon_super,
};

static struct inode *drm_fs_inode_new(void)
{
	struct inode *inode;
	int r;

	r = simple_pin_fs(&drm_fs_type, &drm_fs_mnt, &drm_fs_cnt);
	if (r < 0) {
		DRM_ERROR("Cannot mount pseudo fs: %d\n", r);
		return ERR_PTR(r);
	}

	inode = alloc_anon_inode(drm_fs_mnt->mnt_sb);
	if (IS_ERR(inode))
		simple_release_fs(&drm_fs_mnt, &drm_fs_cnt);

	return inode;
}

static void drm_fs_inode_free(struct inode *inode)
{
	if (inode) {
		iput(inode);
		simple_release_fs(&drm_fs_mnt, &drm_fs_cnt);
	}
}

/**
 * drm_dev_alloc - Allocate new drm device
 * @driver: DRM driver to allocate device for
 * @parent: Parent device object
 *
 * Allocate and initialize a new DRM device. No device registration is done.
 * Call drm_dev_register() to advertice the device to user space and register it
 * with other core subsystems.
 *
 * The initial ref-count of the object is 1. Use drm_dev_ref() and
 * drm_dev_unref() to take and drop further ref-counts.
 *
 * RETURNS:
 * Pointer to new DRM device, or NULL if out of memory.
 */
struct drm_device *drm_dev_alloc(struct drm_driver *driver,
				 struct device *parent)
{
	struct drm_device *dev;
	int ret;

	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
	if (!dev)
		return NULL;

	kref_init(&dev->ref);
	dev->dev = parent;
	dev->driver = driver;

	INIT_LIST_HEAD(&dev->filelist);
	INIT_LIST_HEAD(&dev->ctxlist);
	INIT_LIST_HEAD(&dev->vmalist);
	INIT_LIST_HEAD(&dev->maplist);
	INIT_LIST_HEAD(&dev->vblank_event_list);

	spin_lock_init(&dev->buf_lock);
	spin_lock_init(&dev->event_lock);
	mutex_init(&dev->struct_mutex);
	mutex_init(&dev->ctxlist_mutex);
	mutex_init(&dev->master_mutex);

	dev->anon_inode = drm_fs_inode_new();
	if (IS_ERR(dev->anon_inode)) {
		ret = PTR_ERR(dev->anon_inode);
		DRM_ERROR("Cannot allocate anonymous inode: %d\n", ret);
		goto err_free;
	}

	if (drm_core_check_feature(dev, DRIVER_MODESET)) {
		ret = drm_minor_alloc(dev, DRM_MINOR_CONTROL);
		if (ret)
			goto err_minors;
	}

	if (drm_core_check_feature(dev, DRIVER_RENDER) && drm_rnodes) {
		ret = drm_minor_alloc(dev, DRM_MINOR_RENDER);
		if (ret)
			goto err_minors;
	}

	ret = drm_minor_alloc(dev, DRM_MINOR_LEGACY);
	if (ret)
		goto err_minors;

	if (drm_ht_create(&dev->map_hash, 12))
		goto err_minors;

	ret = drm_ctxbitmap_init(dev);
	if (ret) {
		DRM_ERROR("Cannot allocate memory for context bitmap.\n");
		goto err_ht;
	}

	if (driver->driver_features & DRIVER_GEM) {
		ret = drm_gem_init(dev);
		if (ret) {
			DRM_ERROR("Cannot initialize graphics execution manager (GEM)\n");
			goto err_ctxbitmap;
		}
	}

	return dev;

err_ctxbitmap:
	drm_ctxbitmap_cleanup(dev);
err_ht:
	drm_ht_remove(&dev->map_hash);
err_minors:
	drm_minor_free(dev, DRM_MINOR_LEGACY);
	drm_minor_free(dev, DRM_MINOR_RENDER);
	drm_minor_free(dev, DRM_MINOR_CONTROL);
	drm_fs_inode_free(dev->anon_inode);
err_free:
	mutex_destroy(&dev->master_mutex);
	kfree(dev);
	return NULL;
}
EXPORT_SYMBOL(drm_dev_alloc);

static void drm_dev_release(struct kref *ref)
{
	struct drm_device *dev = container_of(ref, struct drm_device, ref);

	if (dev->driver->driver_features & DRIVER_GEM)
		drm_gem_destroy(dev);

	drm_ctxbitmap_cleanup(dev);
	drm_ht_remove(&dev->map_hash);
	drm_fs_inode_free(dev->anon_inode);

	drm_minor_free(dev, DRM_MINOR_LEGACY);
	drm_minor_free(dev, DRM_MINOR_RENDER);
	drm_minor_free(dev, DRM_MINOR_CONTROL);

	mutex_destroy(&dev->master_mutex);
	kfree(dev);
}

/**
 * drm_dev_ref - Take reference of a DRM device
 * @dev: device to take reference of or NULL
 *
 * This increases the ref-count of @dev by one. You *must* already own a
 * reference when calling this. Use drm_dev_unref() to drop this reference
 * again.
 *
 * This function never fails. However, this function does not provide *any*
 * guarantee whether the device is alive or running. It only provides a
 * reference to the object and the memory associated with it.
 */
void drm_dev_ref(struct drm_device *dev)
{
	if (dev)
		kref_get(&dev->ref);
}
EXPORT_SYMBOL(drm_dev_ref);

/**
 * drm_dev_unref - Drop reference of a DRM device
 * @dev: device to drop reference of or NULL
 *
 * This decreases the ref-count of @dev by one. The device is destroyed if the
 * ref-count drops to zero.
 */
void drm_dev_unref(struct drm_device *dev)
{
	if (dev)
		kref_put(&dev->ref, drm_dev_release);
}
EXPORT_SYMBOL(drm_dev_unref);

/**
 * drm_dev_register - Register DRM device
 * @dev: Device to register
 *
 * Register the DRM device @dev with the system, advertise device to user-space
 * and start normal device operation. @dev must be allocated via drm_dev_alloc()
 * previously.
 *
 * Never call this twice on any device!
 *
 * RETURNS:
 * 0 on success, negative error code on failure.
 */
int drm_dev_register(struct drm_device *dev, unsigned long flags)
{
	int ret;

	mutex_lock(&drm_global_mutex);

	ret = drm_minor_register(dev, DRM_MINOR_CONTROL);
	if (ret)
		goto err_minors;

	ret = drm_minor_register(dev, DRM_MINOR_RENDER);
	if (ret)
		goto err_minors;

	ret = drm_minor_register(dev, DRM_MINOR_LEGACY);
	if (ret)
		goto err_minors;

	if (dev->driver->load) {
		ret = dev->driver->load(dev, flags);
		if (ret)
			goto err_minors;
	}

	/* setup grouping for legacy outputs */
	if (drm_core_check_feature(dev, DRIVER_MODESET)) {
		ret = drm_mode_group_init_legacy_group(dev,
				&dev->primary->mode_group);
		if (ret)
			goto err_unload;
	}

	ret = 0;
	goto out_unlock;

err_unload:
	if (dev->driver->unload)
		dev->driver->unload(dev);
err_minors:
	drm_minor_unregister(dev, DRM_MINOR_LEGACY);
	drm_minor_unregister(dev, DRM_MINOR_RENDER);
	drm_minor_unregister(dev, DRM_MINOR_CONTROL);
out_unlock:
	mutex_unlock(&drm_global_mutex);
	return ret;
}
EXPORT_SYMBOL(drm_dev_register);

/**
 * drm_dev_unregister - Unregister DRM device
 * @dev: Device to unregister
 *
 * Unregister the DRM device from the system. This does the reverse of
 * drm_dev_register() but does not deallocate the device. The caller must call
 * drm_dev_unref() to drop their final reference.
 */
void drm_dev_unregister(struct drm_device *dev)
{
	struct drm_map_list *r_list, *list_temp;

	drm_lastclose(dev);

	if (dev->driver->unload)
		dev->driver->unload(dev);

	if (dev->agp)
		drm_pci_agp_destroy(dev);

	drm_vblank_cleanup(dev);

	list_for_each_entry_safe(r_list, list_temp, &dev->maplist, head)
		drm_rmmap(dev, r_list->map);

	drm_minor_unregister(dev, DRM_MINOR_LEGACY);
	drm_minor_unregister(dev, DRM_MINOR_RENDER);
	drm_minor_unregister(dev, DRM_MINOR_CONTROL);
}
EXPORT_SYMBOL(drm_dev_unregister);