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 /**
  67  * drm_global_item_ref - Initialize and acquire reference to memory
  68  * object
  69  * @ref: Object for initialization
  70  *
  71  * This initializes a memory object, allocating memory and calling the
  72  * .init() hook. Further calls will increase the reference count for
  73  * that item.
  74  *
  75  * Returns:
  76  * Zero on success, non-zero otherwise.
  77  */
  78 int drm_global_item_ref(struct drm_global_reference *ref)
  79 {
  80         int ret = 0;
  81         struct drm_global_item *item = &glob[ref->global_type];
  82
  83         mutex_lock(&item->mutex);
  84         if (item->refcount == 0) {
  85                 ref->object = kzalloc(ref->size, GFP_KERNEL);
  86                 if (unlikely(ref->object == NULL)) {
  87                         ret = -ENOMEM;
  88                         goto error_unlock;
  89                 }
  90                 ret = ref->init(ref);
  91                 if (unlikely(ret != 0))
  92                         goto error_free;
  93
  94                 item->object = ref->object;
  95         } else {
  96                 ref->object = item->object;
  97         }
  98
  99         ++item->refcount;
 100         mutex_unlock(&item->mutex);
 101         return 0;
 102
 103 error_free:
 104         kfree(ref->object);
 105         ref->object = NULL;
 106 error_unlock:
 107         mutex_unlock(&item->mutex);
 108         return ret;
 109 }
 110 EXPORT_SYMBOL(drm_global_item_ref);
 111
 112 /**
 113  * drm_global_item_unref - Drop reference to memory
 114  * object
 115  * @ref: Object being removed
 116  *
 117  * Drop a reference to the memory object and eventually call the
 118  * release() hook.  The allocated object should be dropped in the
 119  * release() hook or before calling this function
 120  *
 121  */
 122
 123 void drm_global_item_unref(struct drm_global_reference *ref)
 124 {
 125         struct drm_global_item *item = &glob[ref->global_type];
 126
 127         mutex_lock(&item->mutex);
 128         BUG_ON(item->refcount == 0);
 129         BUG_ON(ref->object != item->object);
 130         if (--item->refcount == 0) {
 131                 ref->release(ref);
 132                 item->object = NULL;
 133         }
 134         mutex_unlock(&item->mutex);
 135 }
 136 EXPORT_SYMBOL(drm_global_item_unref);
 137