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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 

#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 = malloc(sizeof(*child));

	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;

}

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);

/*

 * Put a block. Merge with the previous and / or next block if they are free.

 * Otherwise add to the free stack.

 */

void drm_mm_put_block(struct drm_mm_node *cur)

{

	struct drm_mm *mm = cur->mm;

	struct list_head *cur_head = &cur->ml_entry;

	struct list_head *root_head = &mm->ml_entry;

	struct drm_mm_node *prev_node = NULL;

	struct drm_mm_node *next_node;

	int merged = 0;

	if (cur_head->prev != root_head) {

		prev_node =

		    list_entry(cur_head->prev, struct drm_mm_node, ml_entry);

		if (prev_node->free) {

			prev_node->size += cur->size;

			merged = 1;

		}

	}

	if (cur_head->next != root_head) {

		next_node =

		    list_entry(cur_head->next, struct drm_mm_node, ml_entry);

		if (next_node->free) {

			if (merged) {

				prev_node->size += next_node->size;

				list_del(&next_node->ml_entry);

				list_del(&next_node->fl_entry);

				if (mm->num_unused < MM_UNUSED_TARGET) {

					list_add(&next_node->fl_entry,

						 &mm->unused_nodes);

					++mm->num_unused;

				} else

					kfree(next_node);

			} else {

				next_node->size += cur->size;

				next_node->start = cur->start;

				merged = 1;

			}

		}

	}

	if (!merged) {

		cur->free = 1;

		list_add(&cur->fl_entry, &mm->fl_entry);

	} else {

		list_del(&cur->ml_entry);

		if (mm->num_unused < MM_UNUSED_TARGET) {

			list_add(&cur->fl_entry, &mm->unused_nodes);

			++mm->num_unused;

		} else

			kfree(cur);

	}

}

EXPORT_SYMBOL(drm_mm_put_block);

struct drm_mm_node *drm_mm_search_free(const struct drm_mm *mm,

				       unsigned long size,

				       unsigned alignment, int best_match)

{

	struct list_head *list;

	const struct list_head *free_stack = &mm->fl_entry;

	struct drm_mm_node *entry;

	struct drm_mm_node *best;

	unsigned long best_size;

	unsigned wasted;

	best = NULL;

	best_size = ~0UL;

	list_for_each(list, free_stack) {

		entry = list_entry(list, struct drm_mm_node, fl_entry);

		wasted = 0;

		if (entry->size < size)

			continue;

		if (alignment) {

			register unsigned tmp = entry->start % alignment;

			if (tmp)

				wasted += alignment - tmp;

		}

		if (entry->size >= size + wasted) {

			if (!best_match)

				return entry;

			if (size < best_size) {

				best = entry;

				best_size = entry->size;

			}

		}

	}

	return best;

}

EXPORT_SYMBOL(drm_mm_search_free);

int drm_mm_clean(struct drm_mm * mm)

{

	struct list_head *head = &mm->ml_entry;

	return (head->next->next == head);

}

EXPORT_SYMBOL(drm_mm_clean);

int drm_mm_init(struct drm_mm * mm, unsigned long start, unsigned long size)

{

	INIT_LIST_HEAD(&mm->ml_entry);

	INIT_LIST_HEAD(&mm->fl_entry);

	INIT_LIST_HEAD(&mm->unused_nodes);

	mm->num_unused = 0;

	spin_lock_init(&mm->unused_lock);

	return drm_mm_create_tail_node(mm, start, size, 0);

}

EXPORT_SYMBOL(drm_mm_init);

void drm_mm_takedown(struct drm_mm * mm)

{

	struct list_head *bnode = mm->fl_entry.next;

	struct drm_mm_node *entry;

	struct drm_mm_node *next;

	entry = list_entry(bnode, struct drm_mm_node, fl_entry);

	if (entry->ml_entry.next != &mm->ml_entry ||

	    entry->fl_entry.next != &mm->fl_entry) {

		DRM_ERROR("Memory manager not clean. Delaying takedown\n");

		return;

	}

	list_del(&entry->fl_entry);

	list_del(&entry->ml_entry);

	kfree(entry);

	spin_lock(&mm->unused_lock);

	list_for_each_entry_safe(entry, next, &mm->unused_nodes, fl_entry) {

		list_del(&entry->fl_entry);

		kfree(entry);

		--mm->num_unused;

	}

	spin_unlock(&mm->unused_lock);

	BUG_ON(mm->num_unused != 0);

}

EXPORT_SYMBOL(drm_mm_takedown);