/**************************************************************************
*
* 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 <thomas-at-tungstengraphics-dot-com>
*/
#include "drmP.h"
drm_mm_node_t *drm_mm_get_block(drm_mm_node_t * parent,
unsigned long size, unsigned alignment)
{
drm_mm_node_t *child;
if (alignment)
size += alignment - 1;
if (parent->size == size) {
list_del_init(&parent->fl_entry);
parent->free = 0;
return parent;
} else {
child = (drm_mm_node_t *) drm_alloc(sizeof(*child), DRM_MEM_MM);
if (!child)
return NULL;
INIT_LIST_HEAD(&child->ml_entry);
INIT_LIST_HEAD(&child->fl_entry);
child->free = 0;
child->size = size;
child->start = parent->start;
list_add_tail(&child->ml_entry, &parent->ml_entry);
parent->size -= size;
parent->start += size;
}
return child;
}
/*
* 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(drm_mm_t * mm, drm_mm_node_t * cur)
{
drm_mm_node_t *list_root = &mm->root_node;
struct list_head *cur_head = &cur->ml_entry;
struct list_head *root_head = &list_root->ml_entry;
drm_mm_node_t *prev_node = NULL;
drm_mm_node_t *next_node;
int merged = 0;
if (cur_head->prev != root_head) {
prev_node = list_entry(cur_head->prev, drm_mm_node_t, 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, drm_mm_node_t, 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);
drm_free(next_node, sizeof(*next_node),
DRM_MEM_MM);
} else {
next_node->size += cur->size;
next_node->start = cur->start;
merged = 1;
}
}
}
if (!merged) {
cur->free = 1;
list_add(&cur->fl_entry, &list_root->fl_entry);
} else {
list_del(&cur->ml_entry);
drm_free(cur, sizeof(*cur), DRM_MEM_MM);
}
}
drm_mm_node_t *drm_mm_search_free(const drm_mm_t * mm,
unsigned long size,
unsigned alignment, int best_match)
{
struct list_head *list;
const struct list_head *free_stack = &mm->root_node.fl_entry;
drm_mm_node_t *entry;
drm_mm_node_t *best;
unsigned long best_size;
best = NULL;
best_size = ~0UL;
if (alignment)
size += alignment - 1;
list_for_each(list, free_stack) {
entry = list_entry(list, drm_mm_node_t, fl_entry);
if (entry->size >= size) {
if (!best_match)
return entry;
if (size < best_size) {
best = entry;
best_size = entry->size;
}
}
}
return best;
}
int drm_mm_init(drm_mm_t * mm, unsigned long start, unsigned long size)
{
drm_mm_node_t *child;
INIT_LIST_HEAD(&mm->root_node.ml_entry);
INIT_LIST_HEAD(&mm->root_node.fl_entry);
child = (drm_mm_node_t *) drm_alloc(sizeof(*child), DRM_MEM_MM);
if (!child)
return -ENOMEM;
INIT_LIST_HEAD(&child->ml_entry);
INIT_LIST_HEAD(&child->fl_entry);
child->start = start;
child->size = size;
child->free = 1;
list_add(&child->fl_entry, &mm->root_node.fl_entry);
list_add(&child->ml_entry, &mm->root_node.ml_entry);
return 0;
}
EXPORT_SYMBOL(drm_mm_init);
void drm_mm_takedown(drm_mm_t * mm)
{
struct list_head *bnode = mm->root_node.fl_entry.next;
drm_mm_node_t *entry;
entry = list_entry(bnode, drm_mm_node_t, fl_entry);
if (entry->ml_entry.next != &mm->root_node.ml_entry ||
entry->fl_entry.next != &mm->root_node.fl_entry) {
DRM_ERROR("Memory manager not clean. Delaying takedown\n");
return;
}
list_del(&entry->fl_entry);
list_del(&entry->ml_entry);
drm_free(entry, sizeof(*entry), DRM_MEM_MM);
}
EXPORT_SYMBOL(drm_mm_takedown);
