drivers/gpu/drm/drm_global.c

   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 <linux/mutex.h>
  32 #include <linux/slab.h>
  33 #include <linux/module.h>
  34 #include <drm/drm_global.h>
  35
  36 struct drm_global_item {
  37         struct mutex mutex;
  38         void *object;
  39         int refcount;
  40 };
  41
  42 static struct drm_global_item glob[DRM_GLOBAL_NUM];
  43
  44 void drm_global_init(void)
  45 {
  46         int i;
  47
  48         for (i = 0; i < DRM_GLOBAL_NUM; ++i) {
  49                 struct drm_global_item *item = &glob[i];
  50                 mutex_init(&item->mutex);
  51                 item->object = NULL;
  52                 item->refcount = 0;
  53         }
  54 }
  55
  56 void drm_global_release(void)
  57 {
  58         int i;
  59         for (i = 0; i < DRM_GLOBAL_NUM; ++i) {
  60                 struct drm_global_item *item = &glob[i];
  61                 BUG_ON(item->object != NULL);
  62                 BUG_ON(item->refcount != 0);
  63         }
  64 }
  65
  66 int drm_global_item_ref(struct drm_global_reference *ref)
  67 {
  68         int ret = 0;
  69         struct drm_global_item *item = &glob[ref->global_type];
  70
  71         mutex_lock(&item->mutex);
  72         if (item->refcount == 0) {
  73                 ref->object = kzalloc(ref->size, GFP_KERNEL);
  74                 if (unlikely(ref->object == NULL)) {
  75                         ret = -ENOMEM;
  76                         goto error_unlock;
  77                 }
  78                 ret = ref->init(ref);
  79                 if (unlikely(ret != 0))
  80                         goto error_free;
  81
  82                 item->object = ref->object;
  83         } else {
  84                 ref->object = item->object;
  85         }
  86
  87         ++item->refcount;
  88         mutex_unlock(&item->mutex);
  89         return 0;
  90
  91 error_free:
  92         kfree(ref->object);
  93         ref->object = NULL;
  94 error_unlock:
  95         mutex_unlock(&item->mutex);
  96         return ret;
  97 }
  98 EXPORT_SYMBOL(drm_global_item_ref);
  99
 100 void drm_global_item_unref(struct drm_global_reference *ref)
 101 {
 102         struct drm_global_item *item = &glob[ref->global_type];
 103
 104         mutex_lock(&item->mutex);
 105         BUG_ON(item->refcount == 0);
 106         BUG_ON(ref->object != item->object);
 107         if (--item->refcount == 0) {
 108                 ref->release(ref);
 109                 item->object = NULL;
 110         }
 111         mutex_unlock(&item->mutex);
 112 }
 113 EXPORT_SYMBOL(drm_global_item_unref);
 114