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 } __attribute__ ((packed));
  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 static int rbtree_open(struct inode *inode, struct file *file)
 181 {
 182         return single_open(file, rbtree_show, inode->i_private);
 183 }
 184
 185 static const struct file_operations rbtree_fops = {
 186         .open           = rbtree_open,
 187         .read           = seq_read,
 188         .llseek         = seq_lseek,
 189         .release        = single_release,
 190 };
 191
 192 static void rbtree_debugfs_init(struct regmap *map)
 193 {
 194         debugfs_create_file("rbtree", 0400, map->debugfs, map, &rbtree_fops);
 195 }
 196 #endif
 197
 198 static int regcache_rbtree_init(struct regmap *map)
 199 {
 200         struct regcache_rbtree_ctx *rbtree_ctx;
 201         int i;
 202         int ret;
 203
 204         map->cache = kmalloc(sizeof *rbtree_ctx, GFP_KERNEL);
 205         if (!map->cache)
 206                 return -ENOMEM;
 207
 208         rbtree_ctx = map->cache;
 209         rbtree_ctx->root = RB_ROOT;
 210         rbtree_ctx->cached_rbnode = NULL;
 211
 212         for (i = 0; i < map->num_reg_defaults; i++) {
 213                 ret = regcache_rbtree_write(map,
 214                                             map->reg_defaults[i].reg,
 215                                             map->reg_defaults[i].def);
 216                 if (ret)
 217                         goto err;
 218         }
 219
 220         return 0;
 221
 222 err:
 223         regcache_rbtree_exit(map);
 224         return ret;
 225 }
 226
 227 static int regcache_rbtree_exit(struct regmap *map)
 228 {
 229         struct rb_node *next;
 230         struct regcache_rbtree_ctx *rbtree_ctx;
 231         struct regcache_rbtree_node *rbtree_node;
 232
 233         /* if we've already been called then just return */
 234         rbtree_ctx = map->cache;
 235         if (!rbtree_ctx)
 236                 return 0;
 237
 238         /* free up the rbtree */
 239         next = rb_first(&rbtree_ctx->root);
 240         while (next) {
 241                 rbtree_node = rb_entry(next, struct regcache_rbtree_node, node);
 242                 next = rb_next(&rbtree_node->node);
 243                 rb_erase(&rbtree_node->node, &rbtree_ctx->root);
 244                 kfree(rbtree_node->cache_present);
 245                 kfree(rbtree_node->block);
 246                 kfree(rbtree_node);
 247         }
 248
 249         /* release the resources */
 250         kfree(map->cache);
 251         map->cache = NULL;
 252
 253         return 0;
 254 }
 255
 256 static int regcache_rbtree_read(struct regmap *map,
 257                                 unsigned int reg, unsigned int *value)
 258 {
 259         struct regcache_rbtree_node *rbnode;
 260         unsigned int reg_tmp;
 261
 262         rbnode = regcache_rbtree_lookup(map, reg);
 263         if (rbnode) {
 264                 reg_tmp = (reg - rbnode->base_reg) / map->reg_stride;
 265                 if (!test_bit(reg_tmp, rbnode->cache_present))
 266                         return -ENOENT;
 267                 *value = regcache_rbtree_get_register(map, rbnode, reg_tmp);
 268         } else {
 269                 return -ENOENT;
 270         }
 271
 272         return 0;
 273 }
 274
 275
 276 static int regcache_rbtree_insert_to_block(struct regmap *map,
 277                                            struct regcache_rbtree_node *rbnode,
 278                                            unsigned int base_reg,
 279                                            unsigned int top_reg,
 280                                            unsigned int reg,
 281                                            unsigned int value)
 282 {
 283         unsigned int blklen;
 284         unsigned int pos, offset;
 285         unsigned long *present;
 286         u8 *blk;
 287
 288         blklen = (top_reg - base_reg) / map->reg_stride + 1;
 289         pos = (reg - base_reg) / map->reg_stride;
 290         offset = (rbnode->base_reg - base_reg) / map->reg_stride;
 291
 292         blk = krealloc(rbnode->block,
 293                        blklen * map->cache_word_size,
 294                        GFP_KERNEL);
 295         if (!blk)
 296                 return -ENOMEM;
 297
 298         rbnode->block = blk;
 299
 300         if (BITS_TO_LONGS(blklen) > BITS_TO_LONGS(rbnode->blklen)) {
 301                 present = krealloc(rbnode->cache_present,
 302                                    BITS_TO_LONGS(blklen) * sizeof(*present),
 303                                    GFP_KERNEL);
 304                 if (!present)
 305                         return -ENOMEM;
 306
 307                 memset(present + BITS_TO_LONGS(rbnode->blklen), 0,
 308                        (BITS_TO_LONGS(blklen) - BITS_TO_LONGS(rbnode->blklen))
 309                        * sizeof(*present));
 310         } else {
 311                 present = rbnode->cache_present;
 312         }
 313
 314         /* insert the register value in the correct place in the rbnode block */
 315         if (pos == 0) {
 316                 memmove(blk + offset * map->cache_word_size,
 317                         blk, rbnode->blklen * map->cache_word_size);
 318                 bitmap_shift_left(present, present, offset, blklen);
 319         }
 320
 321         /* update the rbnode block, its size and the base register */
 322         rbnode->blklen = blklen;
 323         rbnode->base_reg = base_reg;
 324         rbnode->cache_present = present;
 325
 326         regcache_rbtree_set_register(map, rbnode, pos, value);
 327         return 0;
 328 }
 329
 330 static struct regcache_rbtree_node *
 331 regcache_rbtree_node_alloc(struct regmap *map, unsigned int reg)
 332 {
 333         struct regcache_rbtree_node *rbnode;
 334         const struct regmap_range *range;
 335         int i;
 336
 337         rbnode = kzalloc(sizeof(*rbnode), GFP_KERNEL);
 338         if (!rbnode)
 339                 return NULL;
 340
 341         /* If there is a read table then use it to guess at an allocation */
 342         if (map->rd_table) {
 343                 for (i = 0; i < map->rd_table->n_yes_ranges; i++) {
 344                         if (regmap_reg_in_range(reg,
 345                                                 &map->rd_table->yes_ranges[i]))
 346                                 break;
 347                 }
 348
 349                 if (i != map->rd_table->n_yes_ranges) {
 350                         range = &map->rd_table->yes_ranges[i];
 351                         rbnode->blklen = (range->range_max - range->range_min) /
 352                                 map->reg_stride + 1;
 353                         rbnode->base_reg = range->range_min;
 354                 }
 355         }
 356
 357         if (!rbnode->blklen) {
 358                 rbnode->blklen = 1;
 359                 rbnode->base_reg = reg;
 360         }
 361
 362         rbnode->block = kmalloc_array(rbnode->blklen, map->cache_word_size,
 363                                       GFP_KERNEL);
 364         if (!rbnode->block)
 365                 goto err_free;
 366
 367         rbnode->cache_present = kcalloc(BITS_TO_LONGS(rbnode->blklen),
 368                                         sizeof(*rbnode->cache_present),
 369                                         GFP_KERNEL);
 370         if (!rbnode->cache_present)
 371                 goto err_free_block;
 372
 373         return rbnode;
 374
 375 err_free_block:
 376         kfree(rbnode->block);
 377 err_free:
 378         kfree(rbnode);
 379         return NULL;
 380 }
 381
 382 static int regcache_rbtree_write(struct regmap *map, unsigned int reg,
 383                                  unsigned int value)
 384 {
 385         struct regcache_rbtree_ctx *rbtree_ctx;
 386         struct regcache_rbtree_node *rbnode, *rbnode_tmp;
 387         struct rb_node *node;
 388         unsigned int reg_tmp;
 389         int ret;
 390
 391         rbtree_ctx = map->cache;
 392
 393         /* if we can't locate it in the cached rbnode we'll have
 394          * to traverse the rbtree looking for it.
 395          */
 396         rbnode = regcache_rbtree_lookup(map, reg);
 397         if (rbnode) {
 398                 reg_tmp = (reg - rbnode->base_reg) / map->reg_stride;
 399                 regcache_rbtree_set_register(map, rbnode, reg_tmp, value);
 400         } else {
 401                 unsigned int base_reg, top_reg;
 402                 unsigned int new_base_reg, new_top_reg;
 403                 unsigned int min, max;
 404                 unsigned int max_dist;
 405                 unsigned int dist, best_dist = UINT_MAX;
 406
 407                 max_dist = map->reg_stride * sizeof(*rbnode_tmp) /
 408                         map->cache_word_size;
 409                 if (reg < max_dist)
 410                         min = 0;
 411                 else
 412                         min = reg - max_dist;
 413                 max = reg + max_dist;
 414
 415                 /* look for an adjacent register to the one we are about to add */
 416                 node = rbtree_ctx->root.rb_node;
 417                 while (node) {
 418                         rbnode_tmp = rb_entry(node, struct regcache_rbtree_node,
 419                                               node);
 420
 421                         regcache_rbtree_get_base_top_reg(map, rbnode_tmp,
 422                                 &base_reg, &top_reg);
 423
 424                         if (base_reg <= max && top_reg >= min) {
 425                                 if (reg < base_reg)
 426                                         dist = base_reg - reg;
 427                                 else if (reg > top_reg)
 428                                         dist = reg - top_reg;
 429                                 else
 430                                         dist = 0;
 431                                 if (dist < best_dist) {
 432                                         rbnode = rbnode_tmp;
 433                                         best_dist = dist;
 434                                         new_base_reg = min(reg, base_reg);
 435                                         new_top_reg = max(reg, top_reg);
 436                                 }
 437                         }
 438
 439                         /*
 440                          * Keep looking, we want to choose the closest block,
 441                          * otherwise we might end up creating overlapping
 442                          * blocks, which breaks the rbtree.
 443                          */
 444                         if (reg < base_reg)
 445                                 node = node->rb_left;
 446                         else if (reg > top_reg)
 447                                 node = node->rb_right;
 448                         else
 449                                 break;
 450                 }
 451
 452                 if (rbnode) {
 453                         ret = regcache_rbtree_insert_to_block(map, rbnode,
 454                                                               new_base_reg,
 455                                                               new_top_reg, reg,
 456                                                               value);
 457                         if (ret)
 458                                 return ret;
 459                         rbtree_ctx->cached_rbnode = rbnode;
 460                         return 0;
 461                 }
 462
 463                 /* We did not manage to find a place to insert it in
 464                  * an existing block so create a new rbnode.
 465                  */
 466                 rbnode = regcache_rbtree_node_alloc(map, reg);
 467                 if (!rbnode)
 468                         return -ENOMEM;
 469                 regcache_rbtree_set_register(map, rbnode,
 470                                              reg - rbnode->base_reg, value);
 471                 regcache_rbtree_insert(map, &rbtree_ctx->root, rbnode);
 472                 rbtree_ctx->cached_rbnode = rbnode;
 473         }
 474
 475         return 0;
 476 }
 477
 478 static int regcache_rbtree_sync(struct regmap *map, unsigned int min,
 479                                 unsigned int max)
 480 {
 481         struct regcache_rbtree_ctx *rbtree_ctx;
 482         struct rb_node *node;
 483         struct regcache_rbtree_node *rbnode;
 484         unsigned int base_reg, top_reg;
 485         unsigned int start, end;
 486         int ret;
 487
 488         rbtree_ctx = map->cache;
 489         for (node = rb_first(&rbtree_ctx->root); node; node = rb_next(node)) {
 490                 rbnode = rb_entry(node, struct regcache_rbtree_node, node);
 491
 492                 regcache_rbtree_get_base_top_reg(map, rbnode, &base_reg,
 493                         &top_reg);
 494                 if (base_reg > max)
 495                         break;
 496                 if (top_reg < min)
 497                         continue;
 498
 499                 if (min > base_reg)
 500                         start = (min - base_reg) / map->reg_stride;
 501                 else
 502                         start = 0;
 503
 504                 if (max < top_reg)
 505                         end = (max - base_reg) / map->reg_stride + 1;
 506                 else
 507                         end = rbnode->blklen;
 508
 509                 ret = regcache_sync_block(map, rbnode->block,
 510                                           rbnode->cache_present,
 511                                           rbnode->base_reg, start, end);
 512                 if (ret != 0)
 513                         return ret;
 514         }
 515
 516         return regmap_async_complete(map);
 517 }
 518
 519 static int regcache_rbtree_drop(struct regmap *map, unsigned int min,
 520                                 unsigned int max)
 521 {
 522         struct regcache_rbtree_ctx *rbtree_ctx;
 523         struct regcache_rbtree_node *rbnode;
 524         struct rb_node *node;
 525         unsigned int base_reg, top_reg;
 526         unsigned int start, end;
 527
 528         rbtree_ctx = map->cache;
 529         for (node = rb_first(&rbtree_ctx->root); node; node = rb_next(node)) {
 530                 rbnode = rb_entry(node, struct regcache_rbtree_node, node);
 531
 532                 regcache_rbtree_get_base_top_reg(map, rbnode, &base_reg,
 533                         &top_reg);
 534                 if (base_reg > max)
 535                         break;
 536                 if (top_reg < min)
 537                         continue;
 538
 539                 if (min > base_reg)
 540                         start = (min - base_reg) / map->reg_stride;
 541                 else
 542                         start = 0;
 543
 544                 if (max < top_reg)
 545                         end = (max - base_reg) / map->reg_stride + 1;
 546                 else
 547                         end = rbnode->blklen;
 548
 549                 bitmap_clear(rbnode->cache_present, start, end - start);
 550         }
 551
 552         return 0;
 553 }
 554
 555 struct regcache_ops regcache_rbtree_ops = {
 556         .type = REGCACHE_RBTREE,
 557         .name = "rbtree",
 558         .init = regcache_rbtree_init,
 559         .exit = regcache_rbtree_exit,
 560 #ifdef CONFIG_DEBUG_FS
 561         .debugfs_init = rbtree_debugfs_init,
 562 #endif
 563         .read = regcache_rbtree_read,
 564         .write = regcache_rbtree_write,
 565         .sync = regcache_rbtree_sync,
 566         .drop = regcache_rbtree_drop,
 567 };