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/slab.h>
  14 #include <linux/device.h>
  15 #include <linux/debugfs.h>
  16 #include <linux/rbtree.h>
  17 #include <linux/seq_file.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         /* the actual rbtree node holding this block */
  27         struct rb_node node;
  28         /* base register handled by this block */
  29         unsigned int base_reg;
  30         /* block of adjacent registers */
  31         void *block;
  32         /* number of registers available in the block */
  33         unsigned int blklen;
  34 } __attribute__ ((packed));
  35
  36 struct regcache_rbtree_ctx {
  37         struct rb_root root;
  38         struct regcache_rbtree_node *cached_rbnode;
  39 };
  40
  41 static inline void regcache_rbtree_get_base_top_reg(
  42         struct regmap *map,
  43         struct regcache_rbtree_node *rbnode,
  44         unsigned int *base, unsigned int *top)
  45 {
  46         *base = rbnode->base_reg;
  47         *top = rbnode->base_reg + ((rbnode->blklen - 1) * map->reg_stride);
  48 }
  49
  50 static unsigned int regcache_rbtree_get_register(struct regmap *map,
  51         struct regcache_rbtree_node *rbnode, unsigned int idx)
  52 {
  53         return regcache_get_val(map, rbnode->block, idx);
  54 }
  55
  56 static void regcache_rbtree_set_register(struct regmap *map,
  57                                          struct regcache_rbtree_node *rbnode,
  58                                          unsigned int idx, unsigned int val)
  59 {
  60         regcache_set_val(map, rbnode->block, idx, val);
  61 }
  62
  63 static struct regcache_rbtree_node *regcache_rbtree_lookup(struct regmap *map,
  64                                                            unsigned int reg)
  65 {
  66         struct regcache_rbtree_ctx *rbtree_ctx = map->cache;
  67         struct rb_node *node;
  68         struct regcache_rbtree_node *rbnode;
  69         unsigned int base_reg, top_reg;
  70
  71         rbnode = rbtree_ctx->cached_rbnode;
  72         if (rbnode) {
  73                 regcache_rbtree_get_base_top_reg(map, rbnode, &base_reg,
  74                                                  &top_reg);
  75                 if (reg >= base_reg && reg <= top_reg)
  76                         return rbnode;
  77         }
  78
  79         node = rbtree_ctx->root.rb_node;
  80         while (node) {
  81                 rbnode = container_of(node, struct regcache_rbtree_node, node);
  82                 regcache_rbtree_get_base_top_reg(map, rbnode, &base_reg,
  83                                                  &top_reg);
  84                 if (reg >= base_reg && reg <= top_reg) {
  85                         rbtree_ctx->cached_rbnode = rbnode;
  86                         return rbnode;
  87                 } else if (reg > top_reg) {
  88                         node = node->rb_right;
  89                 } else if (reg < base_reg) {
  90                         node = node->rb_left;
  91                 }
  92         }
  93
  94         return NULL;
  95 }
  96
  97 static int regcache_rbtree_insert(struct regmap *map, struct rb_root *root,
  98                                   struct regcache_rbtree_node *rbnode)
  99 {
 100         struct rb_node **new, *parent;
 101         struct regcache_rbtree_node *rbnode_tmp;
 102         unsigned int base_reg_tmp, top_reg_tmp;
 103         unsigned int base_reg;
 104
 105         parent = NULL;
 106         new = &root->rb_node;
 107         while (*new) {
 108                 rbnode_tmp = container_of(*new, struct regcache_rbtree_node,
 109                                           node);
 110                 /* base and top registers of the current rbnode */
 111                 regcache_rbtree_get_base_top_reg(map, rbnode_tmp, &base_reg_tmp,
 112                                                  &top_reg_tmp);
 113                 /* base register of the rbnode to be added */
 114                 base_reg = rbnode->base_reg;
 115                 parent = *new;
 116                 /* if this register has already been inserted, just return */
 117                 if (base_reg >= base_reg_tmp &&
 118                     base_reg <= top_reg_tmp)
 119                         return 0;
 120                 else if (base_reg > top_reg_tmp)
 121                         new = &((*new)->rb_right);
 122                 else if (base_reg < base_reg_tmp)
 123                         new = &((*new)->rb_left);
 124         }
 125
 126         /* insert the node into the rbtree */
 127         rb_link_node(&rbnode->node, parent, new);
 128         rb_insert_color(&rbnode->node, root);
 129
 130         return 1;
 131 }
 132
 133 #ifdef CONFIG_DEBUG_FS
 134 static int rbtree_show(struct seq_file *s, void *ignored)
 135 {
 136         struct regmap *map = s->private;
 137         struct regcache_rbtree_ctx *rbtree_ctx = map->cache;
 138         struct regcache_rbtree_node *n;
 139         struct rb_node *node;
 140         unsigned int base, top;
 141         size_t mem_size;
 142         int nodes = 0;
 143         int registers = 0;
 144         int this_registers, average;
 145
 146         map->lock(map);
 147
 148         mem_size = sizeof(*rbtree_ctx);
 149         mem_size += BITS_TO_LONGS(map->cache_present_nbits) * sizeof(long);
 150
 151         for (node = rb_first(&rbtree_ctx->root); node != NULL;
 152              node = rb_next(node)) {
 153                 n = container_of(node, struct regcache_rbtree_node, node);
 154                 mem_size += sizeof(*n);
 155                 mem_size += (n->blklen * map->cache_word_size);
 156
 157                 regcache_rbtree_get_base_top_reg(map, n, &base, &top);
 158                 this_registers = ((top - base) / map->reg_stride) + 1;
 159                 seq_printf(s, "%x-%x (%d)\n", base, top, this_registers);
 160
 161                 nodes++;
 162                 registers += this_registers;
 163         }
 164
 165         if (nodes)
 166                 average = registers / nodes;
 167         else
 168                 average = 0;
 169
 170         seq_printf(s, "%d nodes, %d registers, average %d registers, used %zu bytes\n",
 171                    nodes, registers, average, mem_size);
 172
 173         map->unlock(map);
 174
 175         return 0;
 176 }
 177
 178 static int rbtree_open(struct inode *inode, struct file *file)
 179 {
 180         return single_open(file, rbtree_show, inode->i_private);
 181 }
 182
 183 static const struct file_operations rbtree_fops = {
 184         .open           = rbtree_open,
 185         .read           = seq_read,
 186         .llseek         = seq_lseek,
 187         .release        = single_release,
 188 };
 189
 190 static void rbtree_debugfs_init(struct regmap *map)
 191 {
 192         debugfs_create_file("rbtree", 0400, map->debugfs, map, &rbtree_fops);
 193 }
 194 #else
 195 static void rbtree_debugfs_init(struct regmap *map)
 196 {
 197 }
 198 #endif
 199
 200 static int regcache_rbtree_init(struct regmap *map)
 201 {
 202         struct regcache_rbtree_ctx *rbtree_ctx;
 203         int i;
 204         int ret;
 205
 206         map->cache = kmalloc(sizeof *rbtree_ctx, GFP_KERNEL);
 207         if (!map->cache)
 208                 return -ENOMEM;
 209
 210         rbtree_ctx = map->cache;
 211         rbtree_ctx->root = RB_ROOT;
 212         rbtree_ctx->cached_rbnode = NULL;
 213
 214         for (i = 0; i < map->num_reg_defaults; i++) {
 215                 ret = regcache_rbtree_write(map,
 216                                             map->reg_defaults[i].reg,
 217                                             map->reg_defaults[i].def);
 218                 if (ret)
 219                         goto err;
 220         }
 221
 222         rbtree_debugfs_init(map);
 223
 224         return 0;
 225
 226 err:
 227         regcache_rbtree_exit(map);
 228         return ret;
 229 }
 230
 231 static int regcache_rbtree_exit(struct regmap *map)
 232 {
 233         struct rb_node *next;
 234         struct regcache_rbtree_ctx *rbtree_ctx;
 235         struct regcache_rbtree_node *rbtree_node;
 236
 237         /* if we've already been called then just return */
 238         rbtree_ctx = map->cache;
 239         if (!rbtree_ctx)
 240                 return 0;
 241
 242         /* free up the rbtree */
 243         next = rb_first(&rbtree_ctx->root);
 244         while (next) {
 245                 rbtree_node = rb_entry(next, struct regcache_rbtree_node, node);
 246                 next = rb_next(&rbtree_node->node);
 247                 rb_erase(&rbtree_node->node, &rbtree_ctx->root);
 248                 kfree(rbtree_node->block);
 249                 kfree(rbtree_node);
 250         }
 251
 252         /* release the resources */
 253         kfree(map->cache);
 254         map->cache = NULL;
 255
 256         return 0;
 257 }
 258
 259 static int regcache_rbtree_read(struct regmap *map,
 260                                 unsigned int reg, unsigned int *value)
 261 {
 262         struct regcache_rbtree_node *rbnode;
 263         unsigned int reg_tmp;
 264
 265         rbnode = regcache_rbtree_lookup(map, reg);
 266         if (rbnode) {
 267                 reg_tmp = (reg - rbnode->base_reg) / map->reg_stride;
 268                 if (!regcache_reg_present(map, reg))
 269                         return -ENOENT;
 270                 *value = regcache_rbtree_get_register(map, rbnode, reg_tmp);
 271         } else {
 272                 return -ENOENT;
 273         }
 274
 275         return 0;
 276 }
 277
 278
 279 static int regcache_rbtree_insert_to_block(struct regmap *map,
 280                                            struct regcache_rbtree_node *rbnode,
 281                                            unsigned int pos, unsigned int reg,
 282                                            unsigned int value)
 283 {
 284         u8 *blk;
 285
 286         blk = krealloc(rbnode->block,
 287                        (rbnode->blklen + 1) * map->cache_word_size,
 288                        GFP_KERNEL);
 289         if (!blk)
 290                 return -ENOMEM;
 291
 292         /* insert the register value in the correct place in the rbnode block */
 293         memmove(blk + (pos + 1) * map->cache_word_size,
 294                 blk + pos * map->cache_word_size,
 295                 (rbnode->blklen - pos) * map->cache_word_size);
 296
 297         /* update the rbnode block, its size and the base register */
 298         rbnode->block = blk;
 299         rbnode->blklen++;
 300         if (!pos)
 301                 rbnode->base_reg = reg;
 302
 303         regcache_rbtree_set_register(map, rbnode, pos, value);
 304         return 0;
 305 }
 306
 307 static int regcache_rbtree_write(struct regmap *map, unsigned int reg,
 308                                  unsigned int value)
 309 {
 310         struct regcache_rbtree_ctx *rbtree_ctx;
 311         struct regcache_rbtree_node *rbnode, *rbnode_tmp;
 312         struct rb_node *node;
 313         unsigned int reg_tmp;
 314         unsigned int pos;
 315         int i;
 316         int ret;
 317
 318         rbtree_ctx = map->cache;
 319         /* update the reg_present bitmap, make space if necessary */
 320         ret = regcache_set_reg_present(map, reg);
 321         if (ret < 0)
 322                 return ret;
 323
 324         /* if we can't locate it in the cached rbnode we'll have
 325          * to traverse the rbtree looking for it.
 326          */
 327         rbnode = regcache_rbtree_lookup(map, reg);
 328         if (rbnode) {
 329                 reg_tmp = (reg - rbnode->base_reg) / map->reg_stride;
 330                 regcache_rbtree_set_register(map, rbnode, reg_tmp, value);
 331         } else {
 332                 /* look for an adjacent register to the one we are about to add */
 333                 for (node = rb_first(&rbtree_ctx->root); node;
 334                      node = rb_next(node)) {
 335                         rbnode_tmp = rb_entry(node, struct regcache_rbtree_node,
 336                                               node);
 337                         for (i = 0; i < rbnode_tmp->blklen; i++) {
 338                                 reg_tmp = rbnode_tmp->base_reg +
 339                                                 (i * map->reg_stride);
 340                                 if (abs(reg_tmp - reg) != map->reg_stride)
 341                                         continue;
 342                                 /* decide where in the block to place our register */
 343                                 if (reg_tmp + map->reg_stride == reg)
 344                                         pos = i + 1;
 345                                 else
 346                                         pos = i;
 347                                 ret = regcache_rbtree_insert_to_block(map,
 348                                                                       rbnode_tmp,
 349                                                                       pos, reg,
 350                                                                       value);
 351                                 if (ret)
 352                                         return ret;
 353                                 rbtree_ctx->cached_rbnode = rbnode_tmp;
 354                                 return 0;
 355                         }
 356                 }
 357                 /* we did not manage to find a place to insert it in an existing
 358                  * block so create a new rbnode with a single register in its block.
 359                  * This block will get populated further if any other adjacent
 360                  * registers get modified in the future.
 361                  */
 362                 rbnode = kzalloc(sizeof *rbnode, GFP_KERNEL);
 363                 if (!rbnode)
 364                         return -ENOMEM;
 365                 rbnode->blklen = sizeof(*rbnode);
 366                 rbnode->base_reg = reg;
 367                 rbnode->block = kmalloc(rbnode->blklen * map->cache_word_size,
 368                                         GFP_KERNEL);
 369                 if (!rbnode->block) {
 370                         kfree(rbnode);
 371                         return -ENOMEM;
 372                 }
 373                 regcache_rbtree_set_register(map, rbnode, 0, value);
 374                 regcache_rbtree_insert(map, &rbtree_ctx->root, rbnode);
 375                 rbtree_ctx->cached_rbnode = rbnode;
 376         }
 377
 378         return 0;
 379 }
 380
 381 static int regcache_rbtree_sync(struct regmap *map, unsigned int min,
 382                                 unsigned int max)
 383 {
 384         struct regcache_rbtree_ctx *rbtree_ctx;
 385         struct rb_node *node;
 386         struct regcache_rbtree_node *rbnode;
 387         int ret;
 388         int base, end;
 389
 390         rbtree_ctx = map->cache;
 391         for (node = rb_first(&rbtree_ctx->root); node; node = rb_next(node)) {
 392                 rbnode = rb_entry(node, struct regcache_rbtree_node, node);
 393
 394                 if (rbnode->base_reg < min)
 395                         continue;
 396                 if (rbnode->base_reg > max)
 397                         break;
 398                 if (rbnode->base_reg + rbnode->blklen < min)
 399                         continue;
 400
 401                 if (min > rbnode->base_reg)
 402                         base = min - rbnode->base_reg;
 403                 else
 404                         base = 0;
 405
 406                 if (max < rbnode->base_reg + rbnode->blklen)
 407                         end = max - rbnode->base_reg + 1;
 408                 else
 409                         end = rbnode->blklen;
 410
 411                 ret = regcache_sync_block(map, rbnode->block, rbnode->base_reg,
 412                                           base, end);
 413                 if (ret != 0)
 414                         return ret;
 415         }
 416
 417         return regmap_async_complete(map);
 418 }
 419
 420 struct regcache_ops regcache_rbtree_ops = {
 421         .type = REGCACHE_RBTREE,
 422         .name = "rbtree",
 423         .init = regcache_rbtree_init,
 424         .exit = regcache_rbtree_exit,
 425         .read = regcache_rbtree_read,
 426         .write = regcache_rbtree_write,
 427         .sync = regcache_rbtree_sync
 428 };