1 /**************************************************************************
2 *
3 * Copyright 2008-2009 VMware, Inc., Palo Alto, CA., USA
4 * All Rights Reserved.
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a
7 * copy of this software and associated documentation files (the
8 * "Software"), to deal in the Software without restriction, including
9 * without limitation the rights to use, copy, modify, merge, publish,
10 * distribute, sub license, and/or sell copies of the Software, and to
11 * permit persons to whom the Software is furnished to do so, subject to
12 * the following conditions:
13 *
14 * The above copyright notice and this permission notice (including the
15 * next paragraph) shall be included in all copies or substantial portions
16 * of the Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
19 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
20 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
21 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
22 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
23 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
24 * USE OR OTHER DEALINGS IN THE SOFTWARE.
25 *
26 **************************************************************************/
27 /*
28 * Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
29 */
30
31 #include <drm/drmP.h>
32 #include <linux/mutex.h>
33 #include <linux/slab.h>
34 #include <linux/module.h>
35 #include <drm/drm_global.h>
36
37 struct drm_global_item {
38 struct lock mutex;
39 void *object;
40 int refcount;
41 };
42
43 static struct drm_global_item glob[DRM_GLOBAL_NUM];
44
drm_global_init(void)45 void drm_global_init(void)
46 {
47 int i;
48
49 for (i = 0; i < DRM_GLOBAL_NUM; ++i) {
50 struct drm_global_item *item = &glob[i];
51 lockinit(&item->mutex, "drmgi", 0, LK_CANRECURSE);
52 item->object = NULL;
53 item->refcount = 0;
54 }
55 }
56
drm_global_release(void)57 void drm_global_release(void)
58 {
59 int i;
60 for (i = 0; i < DRM_GLOBAL_NUM; ++i) {
61 struct drm_global_item *item = &glob[i];
62 BUG_ON(item->object != NULL);
63 BUG_ON(item->refcount != 0);
64 }
65 }
66
67 /**
68 * drm_global_item_ref - Initialize and acquire reference to memory
69 * object
70 * @ref: Object for initialization
71 *
72 * This initializes a memory object, allocating memory and calling the
73 * .init() hook. Further calls will increase the reference count for
74 * that item.
75 *
76 * Returns:
77 * Zero on success, non-zero otherwise.
78 */
drm_global_item_ref(struct drm_global_reference * ref)79 int drm_global_item_ref(struct drm_global_reference *ref)
80 {
81 int ret = 0;
82 struct drm_global_item *item = &glob[ref->global_type];
83
84 mutex_lock(&item->mutex);
85 if (item->refcount == 0) {
86 ref->object = kzalloc(ref->size, GFP_KERNEL);
87 if (unlikely(ref->object == NULL)) {
88 ret = -ENOMEM;
89 goto error_unlock;
90 }
91 ret = ref->init(ref);
92 if (unlikely(ret != 0))
93 goto error_free;
94
95 item->object = ref->object;
96 } else {
97 ref->object = item->object;
98 }
99
100 ++item->refcount;
101 mutex_unlock(&item->mutex);
102 return 0;
103
104 error_free:
105 kfree(ref->object);
106 ref->object = NULL;
107 error_unlock:
108 mutex_unlock(&item->mutex);
109 return ret;
110 }
111 EXPORT_SYMBOL(drm_global_item_ref);
112
113 /**
114 * drm_global_item_unref - Drop reference to memory
115 * object
116 * @ref: Object being removed
117 *
118 * Drop a reference to the memory object and eventually call the
119 * release() hook. The allocated object should be dropped in the
120 * release() hook or before calling this function
121 *
122 */
123
drm_global_item_unref(struct drm_global_reference * ref)124 void drm_global_item_unref(struct drm_global_reference *ref)
125 {
126 struct drm_global_item *item = &glob[ref->global_type];
127
128 mutex_lock(&item->mutex);
129 BUG_ON(item->refcount == 0);
130 BUG_ON(ref->object != item->object);
131 if (--item->refcount == 0) {
132 ref->release(ref);
133 item->object = NULL;
134 }
135 mutex_unlock(&item->mutex);
136 }
137 EXPORT_SYMBOL(drm_global_item_unref);
138
139