drivers/base/regmap/regcache-rbtree.c

   1 /*
   2  * Register cache access API - rbtree caching support
   3  *
   4  * Copyright 2011 Wolfson Microelectronics plc
   5  *
   6  * Author: Dimitris Papastamos <dp@opensource.wolfsonmicro.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12
  13 #include <linux/debugfs.h>
  14 #include <linux/device.h>
  15 #include <linux/rbtree.h>
  16 #include <linux/seq_file.h>
  17 #include <linux/slab.h>
  18
  19 #include "internal.h"
  20
  21 static int regcache_rbtree_write(struct regmap *map, unsigned int reg,
  22                                  unsigned int value);
  23 static int regcache_rbtree_exit(struct regmap *map);
  24
  25 struct regcache_rbtree_node {
  26         /* block of adjacent registers */
  27         void *block;
  28         /* Which registers are present */
  29         long *cache_present;
  30         /* base register handled by this block */
  31         unsigned int base_reg;
  32         /* number of registers available in the block */
  33         unsigned int blklen;
  34         /* the actual rbtree node holding this block */
  35         struct rb_node node;
  36 };
  37
  38 struct regcache_rbtree_ctx {
  39         struct rb_root root;
  40         struct regcache_rbtree_node *cached_rbnode;
  41 };
  42
  43 static inline void regcache_rbtree_get_base_top_reg(
  44         struct regmap *map,
  45         struct regcache_rbtree_node *rbnode,
  46         unsigned int *base, unsigned int *top)
  47 {
  48         *base = rbnode->base_reg;
  49         *top = rbnode->base_reg + ((rbnode->blklen - 1) * map->reg_stride);
  50 }
  51
  52 static unsigned int regcache_rbtree_get_register(struct regmap *map,
  53         struct regcache_rbtree_node *rbnode, unsigned int idx)
  54 {
  55         return regcache_get_val(map, rbnode->block, idx);
  56 }
  57
  58 static void regcache_rbtree_set_register(struct regmap *map,
  59                                          struct regcache_rbtree_node *rbnode,
  60                                          unsigned int idx, unsigned int val)
  61 {
  62         set_bit(idx, rbnode->cache_present);
  63         regcache_set_val(map, rbnode->block, idx, val);
  64 }
  65
  66 static struct regcache_rbtree_node *regcache_rbtree_lookup(struct regmap *map,
  67                                                            unsigned int reg)
  68 {
  69         struct regcache_rbtree_ctx *rbtree_ctx = map->cache;
  70         struct rb_node *node;
  71         struct regcache_rbtree_node *rbnode;
  72         unsigned int base_reg, top_reg;
  73
  74         rbnode = rbtree_ctx->cached_rbnode;
  75         if (rbnode) {
  76                 regcache_rbtree_get_base_top_reg(map, rbnode, &base_reg,
  77                                                  &top_reg);
  78                 if (reg >= base_reg && reg <= top_reg)
  79                         return rbnode;
  80         }
  81
  82         node = rbtree_ctx->root.rb_node;
  83         while (node) {
  84                 rbnode = rb_entry(node, struct regcache_rbtree_node, node);
  85                 regcache_rbtree_get_base_top_reg(map, rbnode, &base_reg,
  86                                                  &top_reg);
  87                 if (reg >= base_reg && reg <= top_reg) {
  88                         rbtree_ctx->cached_rbnode = rbnode;
  89                         return rbnode;
  90                 } else if (reg > top_reg) {
  91                         node = node->rb_right;
  92                 } else if (reg < base_reg) {
  93                         node = node->rb_left;
  94                 }
  95         }
  96
  97         return NULL;
  98 }
  99
 100 static int regcache_rbtree_insert(struct regmap *map, struct rb_root *root,
 101                                   struct regcache_rbtree_node *rbnode)
 102 {
 103         struct rb_node **new, *parent;
 104         struct regcache_rbtree_node *rbnode_tmp;
 105         unsigned int base_reg_tmp, top_reg_tmp;
 106         unsigned int base_reg;
 107
 108         parent = NULL;
 109         new = &root->rb_node;
 110         while (*new) {
 111                 rbnode_tmp = rb_entry(*new, struct regcache_rbtree_node, node);
 112                 /* base and top registers of the current rbnode */
 113                 regcache_rbtree_get_base_top_reg(map, rbnode_tmp, &base_reg_tmp,
 114                                                  &top_reg_tmp);
 115                 /* base register of the rbnode to be added */
 116                 base_reg = rbnode->base_reg;
 117                 parent = *new;
 118                 /* if this register has already been inserted, just return */
 119                 if (base_reg >= base_reg_tmp &&
 120                     base_reg <= top_reg_tmp)
 121                         return 0;
 122                 else if (base_reg > top_reg_tmp)
 123                         new = &((*new)->rb_right);
 124                 else if (base_reg < base_reg_tmp)
 125                         new = &((*new)->rb_left);
 126         }
 127
 128         /* insert the node into the rbtree */
 129         rb_link_node(&rbnode->node, parent, new);
 130         rb_insert_color(&rbnode->node, root);
 131
 132         return 1;
 133 }
 134
 135 #ifdef CONFIG_DEBUG_FS
 136 static int rbtree_show(struct seq_file *s, void *ignored)
 137 {
 138         struct regmap *map = s->private;
 139         struct regcache_rbtree_ctx *rbtree_ctx = map->cache;
 140         struct regcache_rbtree_node *n;
 141         struct rb_node *node;
 142         unsigned int base, top;
 143         size_t mem_size;
 144         int nodes = 0;
 145         int registers = 0;
 146         int this_registers, average;
 147
 148         map->lock(map->lock_arg);
 149
 150         mem_size = sizeof(*rbtree_ctx);
 151
 152         for (node = rb_first(&rbtree_ctx->root); node != NULL;
 153              node = rb_next(node)) {
 154                 n = rb_entry(node, struct regcache_rbtree_node, node);
 155                 mem_size += sizeof(*n);
 156                 mem_size += (n->blklen * map->cache_word_size);
 157                 mem_size += BITS_TO_LONGS(n->blklen) * sizeof(long);
 158
 159                 regcache_rbtree_get_base_top_reg(map, n, &base, &top);
 160                 this_registers = ((top - base) / map->reg_stride) + 1;
 161                 seq_printf(s, "%x-%x (%d)\n", base, top, this_registers);
 162
 163                 nodes++;
 164                 registers += this_registers;
 165         }
 166
 167         if (nodes)
 168                 average = registers / nodes;
 169         else
 170                 average = 0;
 171
 172         seq_printf(s, "%d nodes, %d registers, average %d registers, used %zu bytes\n",
 173                    nodes, registers, average, mem_size);
 174
 175         map->unlock(map->lock_arg);
 176
 177         return 0;
 178 }
 179
 180 DEFINE_SHOW_ATTRIBUTE(rbtree);
 181
 182 static void rbtree_debugfs_init(struct regmap *map)
 183 {
 184         debugfs_create_file("rbtree", 0400, map->debugfs, map, &rbtree_fops);
 185 }
 186 #endif
 187
 188 static int regcache_rbtree_init(struct regmap *map)
 189 {
 190         struct regcache_rbtree_ctx *rbtree_ctx;
 191         int i;
 192         int ret;
 193
 194         map->cache = kmalloc(sizeof *rbtree_ctx, GFP_KERNEL);
 195         if (!map->cache)
 196                 return -ENOMEM;
 197
 198         rbtree_ctx = map->cache;
 199         rbtree_ctx->root = RB_ROOT;
 200         rbtree_ctx->cached_rbnode = NULL;
 201
 202         for (i = 0; i < map->num_reg_defaults; i++) {
 203                 ret = regcache_rbtree_write(map,
 204                                             map->reg_defaults[i].reg,
 205                                             map->reg_defaults[i].def);
 206                 if (ret)
 207                         goto err;
 208         }
 209
 210         return 0;
 211
 212 err:
 213         regcache_rbtree_exit(map);
 214         return ret;
 215 }
 216
 217 static int regcache_rbtree_exit(struct regmap *map)
 218 {
 219         struct rb_node *next;
 220         struct regcache_rbtree_ctx *rbtree_ctx;
 221         struct regcache_rbtree_node *rbtree_node;
 222
 223         /* if we've already been called then just return */
 224         rbtree_ctx = map->cache;
 225         if (!rbtree_ctx)
 226                 return 0;
 227
 228         /* free up the rbtree */
 229         next = rb_first(&rbtree_ctx->root);
 230         while (next) {
 231                 rbtree_node = rb_entry(next, struct regcache_rbtree_node, node);
 232                 next = rb_next(&rbtree_node->node);
 233                 rb_erase(&rbtree_node->node, &rbtree_ctx->root);
 234                 kfree(rbtree_node->cache_present);
 235                 kfree(rbtree_node->block);
 236                 kfree(rbtree_node);
 237         }
 238
 239         /* release the resources */
 240         kfree(map->cache);
 241         map->cache = NULL;
 242
 243         return 0;
 244 }
 245
 246 static int regcache_rbtree_read(struct regmap *map,
 247                                 unsigned int reg, unsigned int *value)
 248 {
 249         struct regcache_rbtree_node *rbnode;
 250         unsigned int reg_tmp;
 251
 252         rbnode = regcache_rbtree_lookup(map, reg);
 253         if (rbnode) {
 254                 reg_tmp = (reg - rbnode->base_reg) / map->reg_stride;
 255                 if (!test_bit(reg_tmp, rbnode->cache_present))
 256                         return -ENOENT;
 257                 *value = regcache_rbtree_get_register(map, rbnode, reg_tmp);
 258         } else {
 259                 return -ENOENT;
 260         }
 261
 262         return 0;
 263 }
 264
 265
 266 static int regcache_rbtree_insert_to_block(struct regmap *map,
 267                                            struct regcache_rbtree_node *rbnode,
 268                                            unsigned int base_reg,
 269                                            unsigned int top_reg,
 270                                            unsigned int reg,
 271                                            unsigned int value)
 272 {
 273         unsigned int blklen;
 274         unsigned int pos, offset;
 275         unsigned long *present;
 276         u8 *blk;
 277
 278         blklen = (top_reg - base_reg) / map->reg_stride + 1;
 279         pos = (reg - base_reg) / map->reg_stride;
 280         offset = (rbnode->base_reg - base_reg) / map->reg_stride;
 281
 282         blk = krealloc(rbnode->block,
 283                        blklen * map->cache_word_size,
 284                        GFP_KERNEL);
 285         if (!blk)
 286                 return -ENOMEM;
 287
 288         if (BITS_TO_LONGS(blklen) > BITS_TO_LONGS(rbnode->blklen)) {
 289                 present = krealloc(rbnode->cache_present,
 290                                    BITS_TO_LONGS(blklen) * sizeof(*present),
 291                                    GFP_KERNEL);
 292                 if (!present) {
 293                         kfree(blk);
 294                         return -ENOMEM;
 295                 }
 296
 297                 memset(present + BITS_TO_LONGS(rbnode->blklen), 0,
 298                        (BITS_TO_LONGS(blklen) - BITS_TO_LONGS(rbnode->blklen))
 299                        * sizeof(*present));
 300         } else {
 301                 present = rbnode->cache_present;
 302         }
 303
 304         /* insert the register value in the correct place in the rbnode block */
 305         if (pos == 0) {
 306                 memmove(blk + offset * map->cache_word_size,
 307                         blk, rbnode->blklen * map->cache_word_size);
 308                 bitmap_shift_left(present, present, offset, blklen);
 309         }
 310
 311         /* update the rbnode block, its size and the base register */
 312         rbnode->block = blk;
 313         rbnode->blklen = blklen;
 314         rbnode->base_reg = base_reg;
 315         rbnode->cache_present = present;
 316
 317         regcache_rbtree_set_register(map, rbnode, pos, value);
 318         return 0;
 319 }
 320
 321 static struct regcache_rbtree_node *
 322 regcache_rbtree_node_alloc(struct regmap *map, unsigned int reg)
 323 {
 324         struct regcache_rbtree_node *rbnode;
 325         const struct regmap_range *range;
 326         int i;
 327
 328         rbnode = kzalloc(sizeof(*rbnode), GFP_KERNEL);
 329         if (!rbnode)
 330                 return NULL;
 331
 332         /* If there is a read table then use it to guess at an allocation */
 333         if (map->rd_table) {
 334                 for (i = 0; i < map->rd_table->n_yes_ranges; i++) {
 335                         if (regmap_reg_in_range(reg,
 336                                                 &map->rd_table->yes_ranges[i]))
 337                                 break;
 338                 }
 339
 340                 if (i != map->rd_table->n_yes_ranges) {
 341                         range = &map->rd_table->yes_ranges[i];
 342                         rbnode->blklen = (range->range_max - range->range_min) /
 343                                 map->reg_stride + 1;
 344                         rbnode->base_reg = range->range_min;
 345                 }
 346         }
 347
 348         if (!rbnode->blklen) {
 349                 rbnode->blklen = 1;
 350                 rbnode->base_reg = reg;
 351         }
 352
 353         rbnode->block = kmalloc_array(rbnode->blklen, map->cache_word_size,
 354                                       GFP_KERNEL);
 355         if (!rbnode->block)
 356                 goto err_free;
 357
 358         rbnode->cache_present = kcalloc(BITS_TO_LONGS(rbnode->blklen),
 359                                         sizeof(*rbnode->cache_present),
 360                                         GFP_KERNEL);
 361         if (!rbnode->cache_present)
 362                 goto err_free_block;
 363
 364         return rbnode;
 365
 366 err_free_block:
 367         kfree(rbnode->block);
 368 err_free:
 369         kfree(rbnode);
 370         return NULL;
 371 }
 372
 373 static int regcache_rbtree_write(struct regmap *map, unsigned int reg,
 374                                  unsigned int value)
 375 {
 376         struct regcache_rbtree_ctx *rbtree_ctx;
 377         struct regcache_rbtree_node *rbnode, *rbnode_tmp;
 378         struct rb_node *node;
 379         unsigned int reg_tmp;
 380         int ret;
 381
 382         rbtree_ctx = map->cache;
 383
 384         /* if we can't locate it in the cached rbnode we'll have
 385          * to traverse the rbtree looking for it.
 386          */
 387         rbnode = regcache_rbtree_lookup(map, reg);
 388         if (rbnode) {
 389                 reg_tmp = (reg - rbnode->base_reg) / map->reg_stride;
 390                 regcache_rbtree_set_register(map, rbnode, reg_tmp, value);
 391         } else {
 392                 unsigned int base_reg, top_reg;
 393                 unsigned int new_base_reg, new_top_reg;
 394                 unsigned int min, max;
 395                 unsigned int max_dist;
 396                 unsigned int dist, best_dist = UINT_MAX;
 397
 398                 max_dist = map->reg_stride * sizeof(*rbnode_tmp) /
 399                         map->cache_word_size;
 400                 if (reg < max_dist)
 401                         min = 0;
 402                 else
 403                         min = reg - max_dist;
 404                 max = reg + max_dist;
 405
 406                 /* look for an adjacent register to the one we are about to add */
 407                 node = rbtree_ctx->root.rb_node;
 408                 while (node) {
 409                         rbnode_tmp = rb_entry(node, struct regcache_rbtree_node,
 410                                               node);
 411
 412                         regcache_rbtree_get_base_top_reg(map, rbnode_tmp,
 413                                 &base_reg, &top_reg);
 414
 415                         if (base_reg <= max && top_reg >= min) {
 416                                 if (reg < base_reg)
 417                                         dist = base_reg - reg;
 418                                 else if (reg > top_reg)
 419                                         dist = reg - top_reg;
 420                                 else
 421                                         dist = 0;
 422                                 if (dist < best_dist) {
 423                                         rbnode = rbnode_tmp;
 424                                         best_dist = dist;
 425                                         new_base_reg = min(reg, base_reg);
 426                                         new_top_reg = max(reg, top_reg);
 427                                 }
 428                         }
 429
 430                         /*
 431                          * Keep looking, we want to choose the closest block,
 432                          * otherwise we might end up creating overlapping
 433                          * blocks, which breaks the rbtree.
 434                          */
 435                         if (reg < base_reg)
 436                                 node = node->rb_left;
 437                         else if (reg > top_reg)
 438                                 node = node->rb_right;
 439                         else
 440                                 break;
 441                 }
 442
 443                 if (rbnode) {
 444                         ret = regcache_rbtree_insert_to_block(map, rbnode,
 445                                                               new_base_reg,
 446                                                               new_top_reg, reg,
 447                                                               value);
 448                         if (ret)
 449                                 return ret;
 450                         rbtree_ctx->cached_rbnode = rbnode;
 451                         return 0;
 452                 }
 453
 454                 /* We did not manage to find a place to insert it in
 455                  * an existing block so create a new rbnode.
 456                  */
 457                 rbnode = regcache_rbtree_node_alloc(map, reg);
 458                 if (!rbnode)
 459                         return -ENOMEM;
 460                 regcache_rbtree_set_register(map, rbnode,
 461                                              reg - rbnode->base_reg, value);
 462                 regcache_rbtree_insert(map, &rbtree_ctx->root, rbnode);
 463                 rbtree_ctx->cached_rbnode = rbnode;
 464         }
 465
 466         return 0;
 467 }
 468
 469 static int regcache_rbtree_sync(struct regmap *map, unsigned int min,
 470                                 unsigned int max)
 471 {
 472         struct regcache_rbtree_ctx *rbtree_ctx;
 473         struct rb_node *node;
 474         struct regcache_rbtree_node *rbnode;
 475         unsigned int base_reg, top_reg;
 476         unsigned int start, end;
 477         int ret;
 478
 479         rbtree_ctx = map->cache;
 480         for (node = rb_first(&rbtree_ctx->root); node; node = rb_next(node)) {
 481                 rbnode = rb_entry(node, struct regcache_rbtree_node, node);
 482
 483                 regcache_rbtree_get_base_top_reg(map, rbnode, &base_reg,
 484                         &top_reg);
 485                 if (base_reg > max)
 486                         break;
 487                 if (top_reg < min)
 488                         continue;
 489
 490                 if (min > base_reg)
 491                         start = (min - base_reg) / map->reg_stride;
 492                 else
 493                         start = 0;
 494
 495                 if (max < top_reg)
 496                         end = (max - base_reg) / map->reg_stride + 1;
 497                 else
 498                         end = rbnode->blklen;
 499
 500                 ret = regcache_sync_block(map, rbnode->block,
 501                                           rbnode->cache_present,
 502                                           rbnode->base_reg, start, end);
 503                 if (ret != 0)
 504                         return ret;
 505         }
 506
 507         return regmap_async_complete(map);
 508 }
 509
 510 static int regcache_rbtree_drop(struct regmap *map, unsigned int min,
 511                                 unsigned int max)
 512 {
 513         struct regcache_rbtree_ctx *rbtree_ctx;
 514         struct regcache_rbtree_node *rbnode;
 515         struct rb_node *node;
 516         unsigned int base_reg, top_reg;
 517         unsigned int start, end;
 518
 519         rbtree_ctx = map->cache;
 520         for (node = rb_first(&rbtree_ctx->root); node; node = rb_next(node)) {
 521                 rbnode = rb_entry(node, struct regcache_rbtree_node, node);
 522
 523                 regcache_rbtree_get_base_top_reg(map, rbnode, &base_reg,
 524                         &top_reg);
 525                 if (base_reg > max)
 526                         break;
 527                 if (top_reg < min)
 528                         continue;
 529
 530                 if (min > base_reg)
 531                         start = (min - base_reg) / map->reg_stride;
 532                 else
 533                         start = 0;
 534
 535                 if (max < top_reg)
 536                         end = (max - base_reg) / map->reg_stride + 1;
 537                 else
 538                         end = rbnode->blklen;
 539
 540                 bitmap_clear(rbnode->cache_present, start, end - start);
 541         }
 542
 543         return 0;
 544 }
 545
 546 struct regcache_ops regcache_rbtree_ops = {
 547         .type = REGCACHE_RBTREE,
 548         .name = "rbtree",
 549         .init = regcache_rbtree_init,
 550         .exit = regcache_rbtree_exit,
 551 #ifdef CONFIG_DEBUG_FS
 552         .debugfs_init = rbtree_debugfs_init,
 553 #endif
 554         .read = regcache_rbtree_read,
 555         .write = regcache_rbtree_write,
 556         .sync = regcache_rbtree_sync,
 557         .drop = regcache_rbtree_drop,
 558 };