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 #include <linux/slab.h>
  46
  47 unsigned long drm_mm_tail_space(struct drm_mm *mm)
  48 {
  49         struct list_head *tail_node;
  50         struct drm_mm_node *entry;
  51
  52         tail_node = mm->ml_entry.prev;
  53         entry = list_entry(tail_node, struct drm_mm_node, ml_entry);
  54         if (!entry->free)
  55                 return 0;
  56
  57         return entry->size;
  58 }
  59
  60 int drm_mm_remove_space_from_tail(struct drm_mm *mm, unsigned long size)
  61 {
  62         struct list_head *tail_node;
  63         struct drm_mm_node *entry;
  64
  65         tail_node = mm->ml_entry.prev;
  66         entry = list_entry(tail_node, struct drm_mm_node, ml_entry);
  67         if (!entry->free)
  68                 return -ENOMEM;
  69
  70         if (entry->size <= size)
  71                 return -ENOMEM;
  72
  73         entry->size -= size;
  74         return 0;
  75 }
  76
  77
  78 static int drm_mm_create_tail_node(struct drm_mm *mm,
  79                             unsigned long start,
  80                             unsigned long size)
  81 {
  82         struct drm_mm_node *child;
  83
  84         child = (struct drm_mm_node *)
  85                 drm_alloc(sizeof(*child), DRM_MEM_MM);
  86         if (!child)
  87                 return -ENOMEM;
  88
  89         child->free = 1;
  90         child->size = size;
  91         child->start = start;
  92         child->mm = mm;
  93
  94         list_add_tail(&child->ml_entry, &mm->ml_entry);
  95         list_add_tail(&child->fl_entry, &mm->fl_entry);
  96
  97         return 0;
  98 }
  99
 100
 101 int drm_mm_add_space_to_tail(struct drm_mm *mm, unsigned long size)
 102 {
 103         struct list_head *tail_node;
 104         struct drm_mm_node *entry;
 105
 106         tail_node = mm->ml_entry.prev;
 107         entry = list_entry(tail_node, struct drm_mm_node, ml_entry);
 108         if (!entry->free) {
 109                 return drm_mm_create_tail_node(mm, entry->start + entry->size, size);
 110         }
 111         entry->size += size;
 112         return 0;
 113 }
 114
 115 static struct drm_mm_node *drm_mm_split_at_start(struct drm_mm_node *parent,
 116                                             unsigned long size)
 117 {
 118         struct drm_mm_node *child;
 119
 120         child = (struct drm_mm_node *)
 121                 drm_alloc(sizeof(*child), DRM_MEM_MM);
 122         if (!child)
 123                 return NULL;
 124
 125         INIT_LIST_HEAD(&child->fl_entry);
 126
 127         child->free = 0;
 128         child->size = size;
 129         child->start = parent->start;
 130         child->mm = parent->mm;
 131
 132         list_add_tail(&child->ml_entry, &parent->ml_entry);
 133         INIT_LIST_HEAD(&child->fl_entry);
 134
 135         parent->size -= size;
 136         parent->start += size;
 137         return child;
 138 }
 139
 140
 141
 142 struct drm_mm_node *drm_mm_get_block(struct drm_mm_node * parent,
 143                                 unsigned long size, unsigned alignment)
 144 {
 145
 146         struct drm_mm_node *align_splitoff = NULL;
 147         struct drm_mm_node *child;
 148         unsigned tmp = 0;
 149
 150         if (alignment)
 151                 tmp = parent->start % alignment;
 152
 153         if (tmp) {
 154                 align_splitoff = drm_mm_split_at_start(parent, alignment - tmp);
 155                 if (!align_splitoff)
 156                         return NULL;
 157         }
 158
 159         if (parent->size == size) {
 160                 list_del_init(&parent->fl_entry);
 161                 parent->free = 0;
 162                 return parent;
 163         } else {
 164                 child = drm_mm_split_at_start(parent, size);
 165         }
 166
 167         if (align_splitoff)
 168                 drm_mm_put_block(align_splitoff);
 169
 170         return child;
 171 }
 172
 173 /*
 174  * Put a block. Merge with the previous and / or next block if they are free.
 175  * Otherwise add to the free stack.
 176  */
 177
 178 void drm_mm_put_block(struct drm_mm_node * cur)
 179 {
 180
 181         struct drm_mm *mm = cur->mm;
 182         struct list_head *cur_head = &cur->ml_entry;
 183         struct list_head *root_head = &mm->ml_entry;
 184         struct drm_mm_node *prev_node = NULL;
 185         struct drm_mm_node *next_node;
 186
 187         int merged = 0;
 188
 189         if (cur_head->prev != root_head) {
 190                 prev_node = list_entry(cur_head->prev, struct drm_mm_node, ml_entry);
 191                 if (prev_node->free) {
 192                         prev_node->size += cur->size;
 193                         merged = 1;
 194                 }
 195         }
 196         if (cur_head->next != root_head) {
 197                 next_node = list_entry(cur_head->next, struct drm_mm_node, ml_entry);
 198                 if (next_node->free) {
 199                         if (merged) {
 200                                 prev_node->size += next_node->size;
 201                                 list_del(&next_node->ml_entry);
 202                                 list_del(&next_node->fl_entry);
 203                                 drm_free(next_node, sizeof(*next_node),
 204                                          DRM_MEM_MM);
 205                         } else {
 206                                 next_node->size += cur->size;
 207                                 next_node->start = cur->start;
 208                                 merged = 1;
 209                         }
 210                 }
 211         }
 212         if (!merged) {
 213                 cur->free = 1;
 214                 list_add(&cur->fl_entry, &mm->fl_entry);
 215         } else {
 216                 list_del(&cur->ml_entry);
 217                 drm_free(cur, sizeof(*cur), DRM_MEM_MM);
 218         }
 219 }
 220
 221 struct drm_mm_node *drm_mm_search_free(const struct drm_mm * mm,
 222                                   unsigned long size,
 223                                   unsigned alignment, int best_match)
 224 {
 225         struct list_head *list;
 226         const struct list_head *free_stack = &mm->fl_entry;
 227         struct drm_mm_node *entry;
 228         struct drm_mm_node *best;
 229         unsigned long best_size;
 230         unsigned wasted;
 231
 232         best = NULL;
 233         best_size = ~0UL;
 234
 235         list_for_each(list, free_stack) {
 236                 entry = list_entry(list, struct drm_mm_node, fl_entry);
 237                 wasted = 0;
 238
 239                 if (entry->size < size)
 240                         continue;
 241
 242                 if (alignment) {
 243                         register unsigned tmp = entry->start % alignment;
 244                         if (tmp)
 245                                 wasted += alignment - tmp;
 246                 }
 247
 248
 249                 if (entry->size >= size + wasted) {
 250                         if (!best_match)
 251                                 return entry;
 252                         if (size < best_size) {
 253                                 best = entry;
 254                                 best_size = entry->size;
 255                         }
 256                 }
 257         }
 258
 259         return best;
 260 }
 261
 262 int drm_mm_clean(struct drm_mm * mm)
 263 {
 264         struct list_head *head = &mm->ml_entry;
 265
 266         return (head->next->next == head);
 267 }
 268
 269 int drm_mm_init(struct drm_mm * mm, unsigned long start, unsigned long size)
 270 {
 271         INIT_LIST_HEAD(&mm->ml_entry);
 272         INIT_LIST_HEAD(&mm->fl_entry);
 273
 274         return drm_mm_create_tail_node(mm, start, size);
 275 }
 276
 277
 278 void drm_mm_takedown(struct drm_mm * mm)
 279 {
 280         struct list_head *bnode = mm->fl_entry.next;
 281         struct drm_mm_node *entry;
 282
 283         entry = list_entry(bnode, struct drm_mm_node, fl_entry);
 284
 285         if (entry->ml_entry.next != &mm->ml_entry ||
 286             entry->fl_entry.next != &mm->fl_entry) {
 287                 DRM_ERROR("Memory manager not clean. Delaying takedown\n");
 288                 return;
 289         }
 290
 291         list_del(&entry->fl_entry);
 292         list_del(&entry->ml_entry);
 293
 294         drm_free(entry, sizeof(*entry), DRM_MEM_MM);
 295 }
 296