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/**************************************************************************

 *

 * Copyright 2006 Tungsten Graphics, Inc., Bismarck, ND., USA.

 * All Rights Reserved.

 *

 * Permission is hereby granted, free of charge, to any person obtaining a

 * copy of this software and associated documentation files (the

 * "Software"), to deal in the Software without restriction, including

 * without limitation the rights to use, copy, modify, merge, publish,

 * distribute, sub license, and/or sell copies of the Software, and to

 * permit persons to whom the Software is furnished to do so, subject to

 * the following conditions:

 *

 * The above copyright notice and this permission notice (including the

 * next paragraph) shall be included in all copies or substantial portions

 * of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL

 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,

 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR

 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE

 * USE OR OTHER DEALINGS IN THE SOFTWARE.

 *

 *

 **************************************************************************/

/*

 * Generic simple memory manager implementation. Intended to be used as a base

 * class implementation for more advanced memory managers.

 *

 * Note that the algorithm used is quite simple and there might be substantial

 * performance gains if a smarter free list is implemented. Currently it is just an

 * unordered stack of free regions. This could easily be improved if an RB-tree

 * is used instead. At least if we expect heavy fragmentation.

 *

 * Aligned allocations can also see improvement.

 *

 * Authors:

 * Thomas Hellström 

 */

#include "drmP.h"

#include "drm_mm.h"

//#include 

#include 

#define MM_UNUSED_TARGET 4

unsigned long drm_mm_tail_space(struct drm_mm *mm)

{

	struct list_head *tail_node;

	struct drm_mm_node *entry;

	tail_node = mm->ml_entry.prev;

	entry = list_entry(tail_node, struct drm_mm_node, ml_entry);

	if (!entry->free)

		return 0;

	return entry->size;

}

int drm_mm_remove_space_from_tail(struct drm_mm *mm, unsigned long size)

{

	struct list_head *tail_node;

	struct drm_mm_node *entry;

	tail_node = mm->ml_entry.prev;

	entry = list_entry(tail_node, struct drm_mm_node, ml_entry);

	if (!entry->free)

		return -ENOMEM;

	if (entry->size <= size)

		return -ENOMEM;

	entry->size -= size;

	return 0;

}

static struct drm_mm_node *drm_mm_kmalloc(struct drm_mm *mm, int atomic)

{

	struct drm_mm_node *child;

    child = kzalloc(sizeof(*child), 0);

	if (unlikely(child == NULL)) {

       spin_lock(&mm->unused_lock);

		if (list_empty(&mm->unused_nodes))

			child = NULL;

		else {

			child =

			    list_entry(mm->unused_nodes.next,

				       struct drm_mm_node, fl_entry);

			list_del(&child->fl_entry);

			--mm->num_unused;

		}

       spin_unlock(&mm->unused_lock);

	}

	return child;

}

/* drm_mm_pre_get() - pre allocate drm_mm_node structure

 * drm_mm:	memory manager struct we are pre-allocating for

 *

 * Returns 0 on success or -ENOMEM if allocation fails.

 */

int drm_mm_pre_get(struct drm_mm *mm)

{

	struct drm_mm_node *node;

	spin_lock(&mm->unused_lock);

	while (mm->num_unused < MM_UNUSED_TARGET) {

		spin_unlock(&mm->unused_lock);

		node = kmalloc(sizeof(*node), GFP_KERNEL);

		spin_lock(&mm->unused_lock);

		if (unlikely(node == NULL)) {

			int ret = (mm->num_unused < 2) ? -ENOMEM : 0;

			spin_unlock(&mm->unused_lock);

			return ret;

		}

		++mm->num_unused;

		list_add_tail(&node->fl_entry, &mm->unused_nodes);

	}

	spin_unlock(&mm->unused_lock);

	return 0;

}

EXPORT_SYMBOL(drm_mm_pre_get);

static int drm_mm_create_tail_node(struct drm_mm *mm,

				   unsigned long start,

				   unsigned long size, int atomic)

{

	struct drm_mm_node *child;

	child = drm_mm_kmalloc(mm, atomic);

	if (unlikely(child == NULL))

		return -ENOMEM;

	child->free = 1;

	child->size = size;

	child->start = start;

	child->mm = mm;

	list_add_tail(&child->ml_entry, &mm->ml_entry);

	list_add_tail(&child->fl_entry, &mm->fl_entry);

	return 0;

}

int drm_mm_add_space_to_tail(struct drm_mm *mm, unsigned long size, int atomic)

{

	struct list_head *tail_node;

	struct drm_mm_node *entry;

	tail_node = mm->ml_entry.prev;

	entry = list_entry(tail_node, struct drm_mm_node, ml_entry);

	if (!entry->free) {

		return drm_mm_create_tail_node(mm, entry->start + entry->size,

					       size, atomic);

	}

	entry->size += size;

	return 0;

}

static struct drm_mm_node *drm_mm_split_at_start(struct drm_mm_node *parent,

						 unsigned long size,

						 int atomic)

{

	struct drm_mm_node *child;

	child = drm_mm_kmalloc(parent->mm, atomic);

	if (unlikely(child == NULL))

		return NULL;

	INIT_LIST_HEAD(&child->fl_entry);

	child->free = 0;

	child->size = size;

	child->start = parent->start;

	child->mm = parent->mm;

	list_add_tail(&child->ml_entry, &parent->ml_entry);

	INIT_LIST_HEAD(&child->fl_entry);

	parent->size -= size;

	parent->start += size;

	return child;

}

struct drm_mm_node *drm_mm_get_block_generic(struct drm_mm_node *node,

					     unsigned long size,

					     unsigned alignment,

					     int atomic)

{

	struct drm_mm_node *align_splitoff = NULL;

	unsigned tmp = 0;

	if (alignment)

		tmp = node->start % alignment;

	if (tmp) {

		align_splitoff =

		    drm_mm_split_at_start(node, alignment - tmp, atomic);

		if (unlikely(align_splitoff == NULL))

			return NULL;

	}

	if (node->size == size) {

		list_del_init(&node->fl_entry);

		node->free = 0;

	} else {

		node = drm_mm_split_at_start(node, size, atomic);

	}

	if (align_splitoff)

		drm_mm_put_block(align_splitoff);

	return node;

}

EXPORT_SYMBOL(drm_mm_get_block_generic);

struct drm_mm_node *drm_mm_get_block_range_generic(struct drm_mm_node *node,

						unsigned long size,

						unsigned alignment,

						unsigned long start,

						unsigned long end,

						int atomic)

{

	struct drm_mm_node *align_splitoff = NULL;

	unsigned tmp = 0;

	unsigned wasted = 0;

	if (node->start < start)

		wasted += start - node->start;

	if (alignment)

		tmp = ((node->start + wasted) % alignment);

	if (tmp)

		wasted += alignment - tmp;

	if (wasted) {

		align_splitoff = drm_mm_split_at_start(node, wasted, atomic);

		if (unlikely(align_splitoff == NULL))

			return NULL;

	}

	if (node->size == size) {

		list_del_init(&node->fl_entry);

		node->free = 0;

	} else {

		node = drm_mm_split_at_start(node, size, atomic);

	}

	if (align_splitoff)

		drm_mm_put_block(align_splitoff);

	return node;

}

EXPORT_SYMBOL(drm_mm_get_block_range_generic);