Merge branch 'master' into upstream-fixes
[linux-2.6] / drivers / char / drm / drm_mm.c
1 /**************************************************************************
2  *
3  * Copyright 2006 Tungsten Graphics, Inc., Bismarck, ND., 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
29 /*
30  * Generic simple memory manager implementation. Intended to be used as a base
31  * class implementation for more advanced memory managers.
32  *
33  * Note that the algorithm used is quite simple and there might be substantial
34  * performance gains if a smarter free list is implemented. Currently it is just an
35  * unordered stack of free regions. This could easily be improved if an RB-tree
36  * is used instead. At least if we expect heavy fragmentation.
37  *
38  * Aligned allocations can also see improvement.
39  *
40  * Authors:
41  * Thomas Hellström <thomas-at-tungstengraphics-dot-com>
42  */
43
44 #include "drmP.h"
45
46 drm_mm_node_t *drm_mm_get_block(drm_mm_node_t * parent,
47                                 unsigned long size, unsigned alignment)
48 {
49
50         drm_mm_node_t *child;
51
52         if (alignment)
53                 size += alignment - 1;
54
55         if (parent->size == size) {
56                 list_del_init(&parent->fl_entry);
57                 parent->free = 0;
58                 return parent;
59         } else {
60                 child = (drm_mm_node_t *) drm_alloc(sizeof(*child), DRM_MEM_MM);
61                 if (!child)
62                         return NULL;
63
64                 INIT_LIST_HEAD(&child->ml_entry);
65                 INIT_LIST_HEAD(&child->fl_entry);
66
67                 child->free = 0;
68                 child->size = size;
69                 child->start = parent->start;
70
71                 list_add_tail(&child->ml_entry, &parent->ml_entry);
72                 parent->size -= size;
73                 parent->start += size;
74         }
75         return child;
76 }
77
78 /*
79  * Put a block. Merge with the previous and / or next block if they are free.
80  * Otherwise add to the free stack.
81  */
82
83 void drm_mm_put_block(drm_mm_t * mm, drm_mm_node_t * cur)
84 {
85
86         drm_mm_node_t *list_root = &mm->root_node;
87         struct list_head *cur_head = &cur->ml_entry;
88         struct list_head *root_head = &list_root->ml_entry;
89         drm_mm_node_t *prev_node = NULL;
90         drm_mm_node_t *next_node;
91
92         int merged = 0;
93
94         if (cur_head->prev != root_head) {
95                 prev_node = list_entry(cur_head->prev, drm_mm_node_t, ml_entry);
96                 if (prev_node->free) {
97                         prev_node->size += cur->size;
98                         merged = 1;
99                 }
100         }
101         if (cur_head->next != root_head) {
102                 next_node = list_entry(cur_head->next, drm_mm_node_t, ml_entry);
103                 if (next_node->free) {
104                         if (merged) {
105                                 prev_node->size += next_node->size;
106                                 list_del(&next_node->ml_entry);
107                                 list_del(&next_node->fl_entry);
108                                 drm_free(next_node, sizeof(*next_node),
109                                          DRM_MEM_MM);
110                         } else {
111                                 next_node->size += cur->size;
112                                 next_node->start = cur->start;
113                                 merged = 1;
114                         }
115                 }
116         }
117         if (!merged) {
118                 cur->free = 1;
119                 list_add(&cur->fl_entry, &list_root->fl_entry);
120         } else {
121                 list_del(&cur->ml_entry);
122                 drm_free(cur, sizeof(*cur), DRM_MEM_MM);
123         }
124 }
125
126 drm_mm_node_t *drm_mm_search_free(const drm_mm_t * mm,
127                                   unsigned long size,
128                                   unsigned alignment, int best_match)
129 {
130         struct list_head *list;
131         const struct list_head *free_stack = &mm->root_node.fl_entry;
132         drm_mm_node_t *entry;
133         drm_mm_node_t *best;
134         unsigned long best_size;
135
136         best = NULL;
137         best_size = ~0UL;
138
139         if (alignment)
140                 size += alignment - 1;
141
142         list_for_each(list, free_stack) {
143                 entry = list_entry(list, drm_mm_node_t, fl_entry);
144                 if (entry->size >= size) {
145                         if (!best_match)
146                                 return entry;
147                         if (size < best_size) {
148                                 best = entry;
149                                 best_size = entry->size;
150                         }
151                 }
152         }
153
154         return best;
155 }
156
157 int drm_mm_init(drm_mm_t * mm, unsigned long start, unsigned long size)
158 {
159         drm_mm_node_t *child;
160
161         INIT_LIST_HEAD(&mm->root_node.ml_entry);
162         INIT_LIST_HEAD(&mm->root_node.fl_entry);
163         child = (drm_mm_node_t *) drm_alloc(sizeof(*child), DRM_MEM_MM);
164         if (!child)
165                 return -ENOMEM;
166
167         INIT_LIST_HEAD(&child->ml_entry);
168         INIT_LIST_HEAD(&child->fl_entry);
169
170         child->start = start;
171         child->size = size;
172         child->free = 1;
173
174         list_add(&child->fl_entry, &mm->root_node.fl_entry);
175         list_add(&child->ml_entry, &mm->root_node.ml_entry);
176
177         return 0;
178 }
179
180 EXPORT_SYMBOL(drm_mm_init);
181
182 void drm_mm_takedown(drm_mm_t * mm)
183 {
184         struct list_head *bnode = mm->root_node.fl_entry.next;
185         drm_mm_node_t *entry;
186
187         entry = list_entry(bnode, drm_mm_node_t, fl_entry);
188
189         if (entry->ml_entry.next != &mm->root_node.ml_entry ||
190             entry->fl_entry.next != &mm->root_node.fl_entry) {
191                 DRM_ERROR("Memory manager not clean. Delaying takedown\n");
192                 return;
193         }
194
195         list_del(&entry->fl_entry);
196         list_del(&entry->ml_entry);
197
198         drm_free(entry, sizeof(*entry), DRM_MEM_MM);
199 }
200
201 EXPORT_SYMBOL(drm_mm_takedown);