xref: /openbmc/linux/drivers/gpu/drm/drm_drv.c (revision 82003e04)
1 /*
2  * Created: Fri Jan 19 10:48:35 2001 by faith@acm.org
3  *
4  * Copyright 2001 VA Linux Systems, Inc., Sunnyvale, California.
5  * All Rights Reserved.
6  *
7  * Author Rickard E. (Rik) Faith <faith@valinux.com>
8  *
9  * Permission is hereby granted, free of charge, to any person obtaining a
10  * copy of this software and associated documentation files (the "Software"),
11  * to deal in the Software without restriction, including without limitation
12  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
13  * and/or sell copies of the Software, and to permit persons to whom the
14  * Software is furnished to do so, subject to the following conditions:
15  *
16  * The above copyright notice and this permission notice (including the next
17  * paragraph) shall be included in all copies or substantial portions of the
18  * Software.
19  *
20  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
21  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
22  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
23  * PRECISION INSIGHT AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
24  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
25  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
26  * DEALINGS IN THE SOFTWARE.
27  */
28 
29 #include <linux/debugfs.h>
30 #include <linux/fs.h>
31 #include <linux/module.h>
32 #include <linux/moduleparam.h>
33 #include <linux/mount.h>
34 #include <linux/slab.h>
35 #include <drm/drmP.h>
36 #include "drm_crtc_internal.h"
37 #include "drm_legacy.h"
38 #include "drm_internal.h"
39 #include "drm_crtc_internal.h"
40 
41 /*
42  * drm_debug: Enable debug output.
43  * Bitmask of DRM_UT_x. See include/drm/drmP.h for details.
44  */
45 unsigned int drm_debug = 0;
46 EXPORT_SYMBOL(drm_debug);
47 
48 MODULE_AUTHOR("Gareth Hughes, Leif Delgass, José Fonseca, Jon Smirl");
49 MODULE_DESCRIPTION("DRM shared core routines");
50 MODULE_LICENSE("GPL and additional rights");
51 MODULE_PARM_DESC(debug, "Enable debug output, where each bit enables a debug category.\n"
52 "\t\tBit 0 (0x01) will enable CORE messages (drm core code)\n"
53 "\t\tBit 1 (0x02) will enable DRIVER messages (drm controller code)\n"
54 "\t\tBit 2 (0x04) will enable KMS messages (modesetting code)\n"
55 "\t\tBit 3 (0x08) will enable PRIME messages (prime code)\n"
56 "\t\tBit 4 (0x10) will enable ATOMIC messages (atomic code)\n"
57 "\t\tBit 5 (0x20) will enable VBL messages (vblank code)");
58 module_param_named(debug, drm_debug, int, 0600);
59 
60 static DEFINE_SPINLOCK(drm_minor_lock);
61 static struct idr drm_minors_idr;
62 
63 static struct dentry *drm_debugfs_root;
64 
65 #define DRM_PRINTK_FMT "[" DRM_NAME ":%s]%s %pV"
66 
67 void drm_dev_printk(const struct device *dev, const char *level,
68 		    unsigned int category, const char *function_name,
69 		    const char *prefix, const char *format, ...)
70 {
71 	struct va_format vaf;
72 	va_list args;
73 
74 	if (category != DRM_UT_NONE && !(drm_debug & category))
75 		return;
76 
77 	va_start(args, format);
78 	vaf.fmt = format;
79 	vaf.va = &args;
80 
81 	if (dev)
82 		dev_printk(level, dev, DRM_PRINTK_FMT, function_name, prefix,
83 			   &vaf);
84 	else
85 		printk("%s" DRM_PRINTK_FMT, level, function_name, prefix, &vaf);
86 
87 	va_end(args);
88 }
89 EXPORT_SYMBOL(drm_dev_printk);
90 
91 void drm_printk(const char *level, unsigned int category,
92 		const char *format, ...)
93 {
94 	struct va_format vaf;
95 	va_list args;
96 
97 	if (category != DRM_UT_NONE && !(drm_debug & category))
98 		return;
99 
100 	va_start(args, format);
101 	vaf.fmt = format;
102 	vaf.va = &args;
103 
104 	printk("%s" "[" DRM_NAME ":%ps]%s %pV",
105 	       level, __builtin_return_address(0),
106 	       strcmp(level, KERN_ERR) == 0 ? " *ERROR*" : "", &vaf);
107 
108 	va_end(args);
109 }
110 EXPORT_SYMBOL(drm_printk);
111 
112 /*
113  * DRM Minors
114  * A DRM device can provide several char-dev interfaces on the DRM-Major. Each
115  * of them is represented by a drm_minor object. Depending on the capabilities
116  * of the device-driver, different interfaces are registered.
117  *
118  * Minors can be accessed via dev->$minor_name. This pointer is either
119  * NULL or a valid drm_minor pointer and stays valid as long as the device is
120  * valid. This means, DRM minors have the same life-time as the underlying
121  * device. However, this doesn't mean that the minor is active. Minors are
122  * registered and unregistered dynamically according to device-state.
123  */
124 
125 static struct drm_minor **drm_minor_get_slot(struct drm_device *dev,
126 					     unsigned int type)
127 {
128 	switch (type) {
129 	case DRM_MINOR_PRIMARY:
130 		return &dev->primary;
131 	case DRM_MINOR_RENDER:
132 		return &dev->render;
133 	case DRM_MINOR_CONTROL:
134 		return &dev->control;
135 	default:
136 		return NULL;
137 	}
138 }
139 
140 static int drm_minor_alloc(struct drm_device *dev, unsigned int type)
141 {
142 	struct drm_minor *minor;
143 	unsigned long flags;
144 	int r;
145 
146 	minor = kzalloc(sizeof(*minor), GFP_KERNEL);
147 	if (!minor)
148 		return -ENOMEM;
149 
150 	minor->type = type;
151 	minor->dev = dev;
152 
153 	idr_preload(GFP_KERNEL);
154 	spin_lock_irqsave(&drm_minor_lock, flags);
155 	r = idr_alloc(&drm_minors_idr,
156 		      NULL,
157 		      64 * type,
158 		      64 * (type + 1),
159 		      GFP_NOWAIT);
160 	spin_unlock_irqrestore(&drm_minor_lock, flags);
161 	idr_preload_end();
162 
163 	if (r < 0)
164 		goto err_free;
165 
166 	minor->index = r;
167 
168 	minor->kdev = drm_sysfs_minor_alloc(minor);
169 	if (IS_ERR(minor->kdev)) {
170 		r = PTR_ERR(minor->kdev);
171 		goto err_index;
172 	}
173 
174 	*drm_minor_get_slot(dev, type) = minor;
175 	return 0;
176 
177 err_index:
178 	spin_lock_irqsave(&drm_minor_lock, flags);
179 	idr_remove(&drm_minors_idr, minor->index);
180 	spin_unlock_irqrestore(&drm_minor_lock, flags);
181 err_free:
182 	kfree(minor);
183 	return r;
184 }
185 
186 static void drm_minor_free(struct drm_device *dev, unsigned int type)
187 {
188 	struct drm_minor **slot, *minor;
189 	unsigned long flags;
190 
191 	slot = drm_minor_get_slot(dev, type);
192 	minor = *slot;
193 	if (!minor)
194 		return;
195 
196 	put_device(minor->kdev);
197 
198 	spin_lock_irqsave(&drm_minor_lock, flags);
199 	idr_remove(&drm_minors_idr, minor->index);
200 	spin_unlock_irqrestore(&drm_minor_lock, flags);
201 
202 	kfree(minor);
203 	*slot = NULL;
204 }
205 
206 static int drm_minor_register(struct drm_device *dev, unsigned int type)
207 {
208 	struct drm_minor *minor;
209 	unsigned long flags;
210 	int ret;
211 
212 	DRM_DEBUG("\n");
213 
214 	minor = *drm_minor_get_slot(dev, type);
215 	if (!minor)
216 		return 0;
217 
218 	ret = drm_debugfs_init(minor, minor->index, drm_debugfs_root);
219 	if (ret) {
220 		DRM_ERROR("DRM: Failed to initialize /sys/kernel/debug/dri.\n");
221 		return ret;
222 	}
223 
224 	ret = device_add(minor->kdev);
225 	if (ret)
226 		goto err_debugfs;
227 
228 	/* replace NULL with @minor so lookups will succeed from now on */
229 	spin_lock_irqsave(&drm_minor_lock, flags);
230 	idr_replace(&drm_minors_idr, minor, minor->index);
231 	spin_unlock_irqrestore(&drm_minor_lock, flags);
232 
233 	DRM_DEBUG("new minor registered %d\n", minor->index);
234 	return 0;
235 
236 err_debugfs:
237 	drm_debugfs_cleanup(minor);
238 	return ret;
239 }
240 
241 static void drm_minor_unregister(struct drm_device *dev, unsigned int type)
242 {
243 	struct drm_minor *minor;
244 	unsigned long flags;
245 
246 	minor = *drm_minor_get_slot(dev, type);
247 	if (!minor || !device_is_registered(minor->kdev))
248 		return;
249 
250 	/* replace @minor with NULL so lookups will fail from now on */
251 	spin_lock_irqsave(&drm_minor_lock, flags);
252 	idr_replace(&drm_minors_idr, NULL, minor->index);
253 	spin_unlock_irqrestore(&drm_minor_lock, flags);
254 
255 	device_del(minor->kdev);
256 	dev_set_drvdata(minor->kdev, NULL); /* safety belt */
257 	drm_debugfs_cleanup(minor);
258 }
259 
260 /**
261  * drm_minor_acquire - Acquire a DRM minor
262  * @minor_id: Minor ID of the DRM-minor
263  *
264  * Looks up the given minor-ID and returns the respective DRM-minor object. The
265  * refence-count of the underlying device is increased so you must release this
266  * object with drm_minor_release().
267  *
268  * As long as you hold this minor, it is guaranteed that the object and the
269  * minor->dev pointer will stay valid! However, the device may get unplugged and
270  * unregistered while you hold the minor.
271  *
272  * Returns:
273  * Pointer to minor-object with increased device-refcount, or PTR_ERR on
274  * failure.
275  */
276 struct drm_minor *drm_minor_acquire(unsigned int minor_id)
277 {
278 	struct drm_minor *minor;
279 	unsigned long flags;
280 
281 	spin_lock_irqsave(&drm_minor_lock, flags);
282 	minor = idr_find(&drm_minors_idr, minor_id);
283 	if (minor)
284 		drm_dev_ref(minor->dev);
285 	spin_unlock_irqrestore(&drm_minor_lock, flags);
286 
287 	if (!minor) {
288 		return ERR_PTR(-ENODEV);
289 	} else if (drm_device_is_unplugged(minor->dev)) {
290 		drm_dev_unref(minor->dev);
291 		return ERR_PTR(-ENODEV);
292 	}
293 
294 	return minor;
295 }
296 
297 /**
298  * drm_minor_release - Release DRM minor
299  * @minor: Pointer to DRM minor object
300  *
301  * Release a minor that was previously acquired via drm_minor_acquire().
302  */
303 void drm_minor_release(struct drm_minor *minor)
304 {
305 	drm_dev_unref(minor->dev);
306 }
307 
308 /**
309  * DOC: driver instance overview
310  *
311  * A device instance for a drm driver is represented by struct &drm_device. This
312  * is allocated with drm_dev_alloc(), usually from bus-specific ->probe()
313  * callbacks implemented by the driver. The driver then needs to initialize all
314  * the various subsystems for the drm device like memory management, vblank
315  * handling, modesetting support and intial output configuration plus obviously
316  * initialize all the corresponding hardware bits. Finally when everything is up
317  * and running and ready for userspace the device instance can be published
318  * using drm_dev_register().
319  *
320  * There is also deprecated support for initalizing device instances using
321  * bus-specific helpers and the ->load() callback. But due to
322  * backwards-compatibility needs the device instance have to be published too
323  * early, which requires unpretty global locking to make safe and is therefore
324  * only support for existing drivers not yet converted to the new scheme.
325  *
326  * When cleaning up a device instance everything needs to be done in reverse:
327  * First unpublish the device instance with drm_dev_unregister(). Then clean up
328  * any other resources allocated at device initialization and drop the driver's
329  * reference to &drm_device using drm_dev_unref().
330  *
331  * Note that the lifetime rules for &drm_device instance has still a lot of
332  * historical baggage. Hence use the reference counting provided by
333  * drm_dev_ref() and drm_dev_unref() only carefully.
334  *
335  * Also note that embedding of &drm_device is currently not (yet) supported (but
336  * it would be easy to add). Drivers can store driver-private data in the
337  * dev_priv field of &drm_device.
338  */
339 
340 static int drm_dev_set_unique(struct drm_device *dev, const char *name)
341 {
342 	if (!name)
343 		return -EINVAL;
344 
345 	kfree(dev->unique);
346 	dev->unique = kstrdup(name, GFP_KERNEL);
347 
348 	return dev->unique ? 0 : -ENOMEM;
349 }
350 
351 /**
352  * drm_put_dev - Unregister and release a DRM device
353  * @dev: DRM device
354  *
355  * Called at module unload time or when a PCI device is unplugged.
356  *
357  * Cleans up all DRM device, calling drm_lastclose().
358  *
359  * Note: Use of this function is deprecated. It will eventually go away
360  * completely.  Please use drm_dev_unregister() and drm_dev_unref() explicitly
361  * instead to make sure that the device isn't userspace accessible any more
362  * while teardown is in progress, ensuring that userspace can't access an
363  * inconsistent state.
364  */
365 void drm_put_dev(struct drm_device *dev)
366 {
367 	DRM_DEBUG("\n");
368 
369 	if (!dev) {
370 		DRM_ERROR("cleanup called no dev\n");
371 		return;
372 	}
373 
374 	drm_dev_unregister(dev);
375 	drm_dev_unref(dev);
376 }
377 EXPORT_SYMBOL(drm_put_dev);
378 
379 void drm_unplug_dev(struct drm_device *dev)
380 {
381 	/* for a USB device */
382 	drm_dev_unregister(dev);
383 
384 	mutex_lock(&drm_global_mutex);
385 
386 	drm_device_set_unplugged(dev);
387 
388 	if (dev->open_count == 0) {
389 		drm_put_dev(dev);
390 	}
391 	mutex_unlock(&drm_global_mutex);
392 }
393 EXPORT_SYMBOL(drm_unplug_dev);
394 
395 /*
396  * DRM internal mount
397  * We want to be able to allocate our own "struct address_space" to control
398  * memory-mappings in VRAM (or stolen RAM, ...). However, core MM does not allow
399  * stand-alone address_space objects, so we need an underlying inode. As there
400  * is no way to allocate an independent inode easily, we need a fake internal
401  * VFS mount-point.
402  *
403  * The drm_fs_inode_new() function allocates a new inode, drm_fs_inode_free()
404  * frees it again. You are allowed to use iget() and iput() to get references to
405  * the inode. But each drm_fs_inode_new() call must be paired with exactly one
406  * drm_fs_inode_free() call (which does not have to be the last iput()).
407  * We use drm_fs_inode_*() to manage our internal VFS mount-point and share it
408  * between multiple inode-users. You could, technically, call
409  * iget() + drm_fs_inode_free() directly after alloc and sometime later do an
410  * iput(), but this way you'd end up with a new vfsmount for each inode.
411  */
412 
413 static int drm_fs_cnt;
414 static struct vfsmount *drm_fs_mnt;
415 
416 static const struct dentry_operations drm_fs_dops = {
417 	.d_dname	= simple_dname,
418 };
419 
420 static const struct super_operations drm_fs_sops = {
421 	.statfs		= simple_statfs,
422 };
423 
424 static struct dentry *drm_fs_mount(struct file_system_type *fs_type, int flags,
425 				   const char *dev_name, void *data)
426 {
427 	return mount_pseudo(fs_type,
428 			    "drm:",
429 			    &drm_fs_sops,
430 			    &drm_fs_dops,
431 			    0x010203ff);
432 }
433 
434 static struct file_system_type drm_fs_type = {
435 	.name		= "drm",
436 	.owner		= THIS_MODULE,
437 	.mount		= drm_fs_mount,
438 	.kill_sb	= kill_anon_super,
439 };
440 
441 static struct inode *drm_fs_inode_new(void)
442 {
443 	struct inode *inode;
444 	int r;
445 
446 	r = simple_pin_fs(&drm_fs_type, &drm_fs_mnt, &drm_fs_cnt);
447 	if (r < 0) {
448 		DRM_ERROR("Cannot mount pseudo fs: %d\n", r);
449 		return ERR_PTR(r);
450 	}
451 
452 	inode = alloc_anon_inode(drm_fs_mnt->mnt_sb);
453 	if (IS_ERR(inode))
454 		simple_release_fs(&drm_fs_mnt, &drm_fs_cnt);
455 
456 	return inode;
457 }
458 
459 static void drm_fs_inode_free(struct inode *inode)
460 {
461 	if (inode) {
462 		iput(inode);
463 		simple_release_fs(&drm_fs_mnt, &drm_fs_cnt);
464 	}
465 }
466 
467 /**
468  * drm_dev_init - Initialise new DRM device
469  * @dev: DRM device
470  * @driver: DRM driver
471  * @parent: Parent device object
472  *
473  * Initialize a new DRM device. No device registration is done.
474  * Call drm_dev_register() to advertice the device to user space and register it
475  * with other core subsystems. This should be done last in the device
476  * initialization sequence to make sure userspace can't access an inconsistent
477  * state.
478  *
479  * The initial ref-count of the object is 1. Use drm_dev_ref() and
480  * drm_dev_unref() to take and drop further ref-counts.
481  *
482  * Note that for purely virtual devices @parent can be NULL.
483  *
484  * Drivers that do not want to allocate their own device struct
485  * embedding struct &drm_device can call drm_dev_alloc() instead.
486  *
487  * RETURNS:
488  * 0 on success, or error code on failure.
489  */
490 int drm_dev_init(struct drm_device *dev,
491 		 struct drm_driver *driver,
492 		 struct device *parent)
493 {
494 	int ret;
495 
496 	kref_init(&dev->ref);
497 	dev->dev = parent;
498 	dev->driver = driver;
499 
500 	INIT_LIST_HEAD(&dev->filelist);
501 	INIT_LIST_HEAD(&dev->ctxlist);
502 	INIT_LIST_HEAD(&dev->vmalist);
503 	INIT_LIST_HEAD(&dev->maplist);
504 	INIT_LIST_HEAD(&dev->vblank_event_list);
505 
506 	spin_lock_init(&dev->buf_lock);
507 	spin_lock_init(&dev->event_lock);
508 	mutex_init(&dev->struct_mutex);
509 	mutex_init(&dev->filelist_mutex);
510 	mutex_init(&dev->ctxlist_mutex);
511 	mutex_init(&dev->master_mutex);
512 
513 	dev->anon_inode = drm_fs_inode_new();
514 	if (IS_ERR(dev->anon_inode)) {
515 		ret = PTR_ERR(dev->anon_inode);
516 		DRM_ERROR("Cannot allocate anonymous inode: %d\n", ret);
517 		goto err_free;
518 	}
519 
520 	if (drm_core_check_feature(dev, DRIVER_MODESET)) {
521 		ret = drm_minor_alloc(dev, DRM_MINOR_CONTROL);
522 		if (ret)
523 			goto err_minors;
524 	}
525 
526 	if (drm_core_check_feature(dev, DRIVER_RENDER)) {
527 		ret = drm_minor_alloc(dev, DRM_MINOR_RENDER);
528 		if (ret)
529 			goto err_minors;
530 	}
531 
532 	ret = drm_minor_alloc(dev, DRM_MINOR_PRIMARY);
533 	if (ret)
534 		goto err_minors;
535 
536 	ret = drm_ht_create(&dev->map_hash, 12);
537 	if (ret)
538 		goto err_minors;
539 
540 	drm_legacy_ctxbitmap_init(dev);
541 
542 	if (drm_core_check_feature(dev, DRIVER_GEM)) {
543 		ret = drm_gem_init(dev);
544 		if (ret) {
545 			DRM_ERROR("Cannot initialize graphics execution manager (GEM)\n");
546 			goto err_ctxbitmap;
547 		}
548 	}
549 
550 	/* Use the parent device name as DRM device unique identifier, but fall
551 	 * back to the driver name for virtual devices like vgem. */
552 	ret = drm_dev_set_unique(dev, parent ? dev_name(parent) : driver->name);
553 	if (ret)
554 		goto err_setunique;
555 
556 	return 0;
557 
558 err_setunique:
559 	if (drm_core_check_feature(dev, DRIVER_GEM))
560 		drm_gem_destroy(dev);
561 err_ctxbitmap:
562 	drm_legacy_ctxbitmap_cleanup(dev);
563 	drm_ht_remove(&dev->map_hash);
564 err_minors:
565 	drm_minor_free(dev, DRM_MINOR_PRIMARY);
566 	drm_minor_free(dev, DRM_MINOR_RENDER);
567 	drm_minor_free(dev, DRM_MINOR_CONTROL);
568 	drm_fs_inode_free(dev->anon_inode);
569 err_free:
570 	mutex_destroy(&dev->master_mutex);
571 	return ret;
572 }
573 EXPORT_SYMBOL(drm_dev_init);
574 
575 /**
576  * drm_dev_alloc - Allocate new DRM device
577  * @driver: DRM driver to allocate device for
578  * @parent: Parent device object
579  *
580  * Allocate and initialize a new DRM device. No device registration is done.
581  * Call drm_dev_register() to advertice the device to user space and register it
582  * with other core subsystems. This should be done last in the device
583  * initialization sequence to make sure userspace can't access an inconsistent
584  * state.
585  *
586  * The initial ref-count of the object is 1. Use drm_dev_ref() and
587  * drm_dev_unref() to take and drop further ref-counts.
588  *
589  * Note that for purely virtual devices @parent can be NULL.
590  *
591  * Drivers that wish to subclass or embed struct &drm_device into their
592  * own struct should look at using drm_dev_init() instead.
593  *
594  * RETURNS:
595  * Pointer to new DRM device, or ERR_PTR on failure.
596  */
597 struct drm_device *drm_dev_alloc(struct drm_driver *driver,
598 				 struct device *parent)
599 {
600 	struct drm_device *dev;
601 	int ret;
602 
603 	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
604 	if (!dev)
605 		return ERR_PTR(-ENOMEM);
606 
607 	ret = drm_dev_init(dev, driver, parent);
608 	if (ret) {
609 		kfree(dev);
610 		return ERR_PTR(ret);
611 	}
612 
613 	return dev;
614 }
615 EXPORT_SYMBOL(drm_dev_alloc);
616 
617 static void drm_dev_release(struct kref *ref)
618 {
619 	struct drm_device *dev = container_of(ref, struct drm_device, ref);
620 
621 	if (drm_core_check_feature(dev, DRIVER_GEM))
622 		drm_gem_destroy(dev);
623 
624 	drm_legacy_ctxbitmap_cleanup(dev);
625 	drm_ht_remove(&dev->map_hash);
626 	drm_fs_inode_free(dev->anon_inode);
627 
628 	drm_minor_free(dev, DRM_MINOR_PRIMARY);
629 	drm_minor_free(dev, DRM_MINOR_RENDER);
630 	drm_minor_free(dev, DRM_MINOR_CONTROL);
631 
632 	mutex_destroy(&dev->master_mutex);
633 	kfree(dev->unique);
634 	kfree(dev);
635 }
636 
637 /**
638  * drm_dev_ref - Take reference of a DRM device
639  * @dev: device to take reference of or NULL
640  *
641  * This increases the ref-count of @dev by one. You *must* already own a
642  * reference when calling this. Use drm_dev_unref() to drop this reference
643  * again.
644  *
645  * This function never fails. However, this function does not provide *any*
646  * guarantee whether the device is alive or running. It only provides a
647  * reference to the object and the memory associated with it.
648  */
649 void drm_dev_ref(struct drm_device *dev)
650 {
651 	if (dev)
652 		kref_get(&dev->ref);
653 }
654 EXPORT_SYMBOL(drm_dev_ref);
655 
656 /**
657  * drm_dev_unref - Drop reference of a DRM device
658  * @dev: device to drop reference of or NULL
659  *
660  * This decreases the ref-count of @dev by one. The device is destroyed if the
661  * ref-count drops to zero.
662  */
663 void drm_dev_unref(struct drm_device *dev)
664 {
665 	if (dev)
666 		kref_put(&dev->ref, drm_dev_release);
667 }
668 EXPORT_SYMBOL(drm_dev_unref);
669 
670 /**
671  * drm_dev_register - Register DRM device
672  * @dev: Device to register
673  * @flags: Flags passed to the driver's .load() function
674  *
675  * Register the DRM device @dev with the system, advertise device to user-space
676  * and start normal device operation. @dev must be allocated via drm_dev_alloc()
677  * previously.
678  *
679  * Never call this twice on any device!
680  *
681  * NOTE: To ensure backward compatibility with existing drivers method this
682  * function calls the ->load() method after registering the device nodes,
683  * creating race conditions. Usage of the ->load() methods is therefore
684  * deprecated, drivers must perform all initialization before calling
685  * drm_dev_register().
686  *
687  * RETURNS:
688  * 0 on success, negative error code on failure.
689  */
690 int drm_dev_register(struct drm_device *dev, unsigned long flags)
691 {
692 	int ret;
693 
694 	mutex_lock(&drm_global_mutex);
695 
696 	ret = drm_minor_register(dev, DRM_MINOR_CONTROL);
697 	if (ret)
698 		goto err_minors;
699 
700 	ret = drm_minor_register(dev, DRM_MINOR_RENDER);
701 	if (ret)
702 		goto err_minors;
703 
704 	ret = drm_minor_register(dev, DRM_MINOR_PRIMARY);
705 	if (ret)
706 		goto err_minors;
707 
708 	if (dev->driver->load) {
709 		ret = dev->driver->load(dev, flags);
710 		if (ret)
711 			goto err_minors;
712 	}
713 
714 	if (drm_core_check_feature(dev, DRIVER_MODESET))
715 		drm_modeset_register_all(dev);
716 
717 	ret = 0;
718 	goto out_unlock;
719 
720 err_minors:
721 	drm_minor_unregister(dev, DRM_MINOR_PRIMARY);
722 	drm_minor_unregister(dev, DRM_MINOR_RENDER);
723 	drm_minor_unregister(dev, DRM_MINOR_CONTROL);
724 out_unlock:
725 	mutex_unlock(&drm_global_mutex);
726 	return ret;
727 }
728 EXPORT_SYMBOL(drm_dev_register);
729 
730 /**
731  * drm_dev_unregister - Unregister DRM device
732  * @dev: Device to unregister
733  *
734  * Unregister the DRM device from the system. This does the reverse of
735  * drm_dev_register() but does not deallocate the device. The caller must call
736  * drm_dev_unref() to drop their final reference.
737  *
738  * This should be called first in the device teardown code to make sure
739  * userspace can't access the device instance any more.
740  */
741 void drm_dev_unregister(struct drm_device *dev)
742 {
743 	struct drm_map_list *r_list, *list_temp;
744 
745 	drm_lastclose(dev);
746 
747 	if (drm_core_check_feature(dev, DRIVER_MODESET))
748 		drm_modeset_unregister_all(dev);
749 
750 	if (dev->driver->unload)
751 		dev->driver->unload(dev);
752 
753 	if (dev->agp)
754 		drm_pci_agp_destroy(dev);
755 
756 	drm_vblank_cleanup(dev);
757 
758 	list_for_each_entry_safe(r_list, list_temp, &dev->maplist, head)
759 		drm_legacy_rmmap(dev, r_list->map);
760 
761 	drm_minor_unregister(dev, DRM_MINOR_PRIMARY);
762 	drm_minor_unregister(dev, DRM_MINOR_RENDER);
763 	drm_minor_unregister(dev, DRM_MINOR_CONTROL);
764 }
765 EXPORT_SYMBOL(drm_dev_unregister);
766 
767 /*
768  * DRM Core
769  * The DRM core module initializes all global DRM objects and makes them
770  * available to drivers. Once setup, drivers can probe their respective
771  * devices.
772  * Currently, core management includes:
773  *  - The "DRM-Global" key/value database
774  *  - Global ID management for connectors
775  *  - DRM major number allocation
776  *  - DRM minor management
777  *  - DRM sysfs class
778  *  - DRM debugfs root
779  *
780  * Furthermore, the DRM core provides dynamic char-dev lookups. For each
781  * interface registered on a DRM device, you can request minor numbers from DRM
782  * core. DRM core takes care of major-number management and char-dev
783  * registration. A stub ->open() callback forwards any open() requests to the
784  * registered minor.
785  */
786 
787 static int drm_stub_open(struct inode *inode, struct file *filp)
788 {
789 	const struct file_operations *new_fops;
790 	struct drm_minor *minor;
791 	int err;
792 
793 	DRM_DEBUG("\n");
794 
795 	mutex_lock(&drm_global_mutex);
796 	minor = drm_minor_acquire(iminor(inode));
797 	if (IS_ERR(minor)) {
798 		err = PTR_ERR(minor);
799 		goto out_unlock;
800 	}
801 
802 	new_fops = fops_get(minor->dev->driver->fops);
803 	if (!new_fops) {
804 		err = -ENODEV;
805 		goto out_release;
806 	}
807 
808 	replace_fops(filp, new_fops);
809 	if (filp->f_op->open)
810 		err = filp->f_op->open(inode, filp);
811 	else
812 		err = 0;
813 
814 out_release:
815 	drm_minor_release(minor);
816 out_unlock:
817 	mutex_unlock(&drm_global_mutex);
818 	return err;
819 }
820 
821 static const struct file_operations drm_stub_fops = {
822 	.owner = THIS_MODULE,
823 	.open = drm_stub_open,
824 	.llseek = noop_llseek,
825 };
826 
827 static void drm_core_exit(void)
828 {
829 	unregister_chrdev(DRM_MAJOR, "drm");
830 	debugfs_remove(drm_debugfs_root);
831 	drm_sysfs_destroy();
832 	idr_destroy(&drm_minors_idr);
833 	drm_connector_ida_destroy();
834 	drm_global_release();
835 }
836 
837 static int __init drm_core_init(void)
838 {
839 	int ret;
840 
841 	drm_global_init();
842 	drm_connector_ida_init();
843 	idr_init(&drm_minors_idr);
844 
845 	ret = drm_sysfs_init();
846 	if (ret < 0) {
847 		DRM_ERROR("Cannot create DRM class: %d\n", ret);
848 		goto error;
849 	}
850 
851 	drm_debugfs_root = debugfs_create_dir("dri", NULL);
852 	if (!drm_debugfs_root) {
853 		ret = -ENOMEM;
854 		DRM_ERROR("Cannot create debugfs-root: %d\n", ret);
855 		goto error;
856 	}
857 
858 	ret = register_chrdev(DRM_MAJOR, "drm", &drm_stub_fops);
859 	if (ret < 0)
860 		goto error;
861 
862 	DRM_INFO("Initialized\n");
863 	return 0;
864 
865 error:
866 	drm_core_exit();
867 	return ret;
868 }
869 
870 module_init(drm_core_init);
871 module_exit(drm_core_exit);
872