LXR linux/drivers/gpu/drm/drm

   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
  36struct drm_global_item {
  37        struct mutex mutex;
  38        void *object;
  39        int refcount;
  40};
  41
  42static struct drm_global_item glob[DRM_GLOBAL_NUM];
  43
  44void 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
  56void 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 */
  78int 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
 103error_free:
 104        kfree(ref->object);
 105        ref->object = NULL;
 106error_unlock:
 107        mutex_unlock(&item->mutex);
 108        return ret;
 109}
 110EXPORT_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
 123void 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}
 136EXPORT_SYMBOL(drm_global_item_unref);
 137
 138