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/debugfs.h>
  15 #include <linux/rbtree.h>
  16 #include <linux/seq_file.h>
  17
  18 #include "internal.h"
  19
  20 static int regcache_rbtree_write(struct regmap *map, unsigned int reg,
  21                                  unsigned int value);
  22 static int regcache_rbtree_exit(struct regmap *map);
  23
  24 struct regcache_rbtree_node {
  25         /* the actual rbtree node holding this block */
  26         struct rb_node node;
  27         /* base register handled by this block */
  28         unsigned int base_reg;
  29         /* block of adjacent registers */
  30         void *block;
  31         /* number of registers available in the block */
  32         unsigned int blklen;
  33 } __attribute__ ((packed));
  34
  35 struct regcache_rbtree_ctx {
  36         struct rb_root root;
  37         struct regcache_rbtree_node *cached_rbnode;
  38 };
  39
  40 static inline void regcache_rbtree_get_base_top_reg(
  41         struct regcache_rbtree_node *rbnode,
  42         unsigned int *base, unsigned int *top)
  43 {
  44         *base = rbnode->base_reg;
  45         *top = rbnode->base_reg + rbnode->blklen - 1;
  46 }
  47
  48 static unsigned int regcache_rbtree_get_register(
  49         struct regcache_rbtree_node *rbnode, unsigned int idx,
  50         unsigned int word_size)
  51 {
  52         return regcache_get_val(rbnode->block, idx, word_size);
  53 }
  54
  55 static void regcache_rbtree_set_register(struct regcache_rbtree_node *rbnode,
  56                                          unsigned int idx, unsigned int val,
  57                                          unsigned int word_size)
  58 {
  59         regcache_set_val(rbnode->block, idx, val, word_size);
  60 }
  61
  62 static struct regcache_rbtree_node *regcache_rbtree_lookup(struct regmap *map,
  63         unsigned int reg)
  64 {
  65         struct regcache_rbtree_ctx *rbtree_ctx = map->cache;
  66         struct rb_node *node;
  67         struct regcache_rbtree_node *rbnode;
  68         unsigned int base_reg, top_reg;
  69
  70         rbnode = rbtree_ctx->cached_rbnode;
  71         if (rbnode) {
  72                 regcache_rbtree_get_base_top_reg(rbnode, &base_reg, &top_reg);
  73                 if (reg >= base_reg && reg <= top_reg)
  74                         return rbnode;
  75         }
  76
  77         node = rbtree_ctx->root.rb_node;
  78         while (node) {
  79                 rbnode = container_of(node, struct regcache_rbtree_node, node);
  80                 regcache_rbtree_get_base_top_reg(rbnode, &base_reg, &top_reg);
  81                 if (reg >= base_reg && reg <= top_reg) {
  82                         rbtree_ctx->cached_rbnode = rbnode;
  83                         return rbnode;
  84                 } else if (reg > top_reg) {
  85                         node = node->rb_right;
  86                 } else if (reg < base_reg) {
  87                         node = node->rb_left;
  88                 }
  89         }
  90
  91         return NULL;
  92 }
  93
  94 static int regcache_rbtree_insert(struct rb_root *root,
  95                                   struct regcache_rbtree_node *rbnode)
  96 {
  97         struct rb_node **new, *parent;
  98         struct regcache_rbtree_node *rbnode_tmp;
  99         unsigned int base_reg_tmp, top_reg_tmp;
 100         unsigned int base_reg;
 101
 102         parent = NULL;
 103         new = &root->rb_node;
 104         while (*new) {
 105                 rbnode_tmp = container_of(*new, struct regcache_rbtree_node,
 106                                           node);
 107                 /* base and top registers of the current rbnode */
 108                 regcache_rbtree_get_base_top_reg(rbnode_tmp, &base_reg_tmp,
 109                                                  &top_reg_tmp);
 110                 /* base register of the rbnode to be added */
 111                 base_reg = rbnode->base_reg;
 112                 parent = *new;
 113                 /* if this register has already been inserted, just return */
 114                 if (base_reg >= base_reg_tmp &&
 115                     base_reg <= top_reg_tmp)
 116                         return 0;
 117                 else if (base_reg > top_reg_tmp)
 118                         new = &((*new)->rb_right);
 119                 else if (base_reg < base_reg_tmp)
 120                         new = &((*new)->rb_left);
 121         }
 122
 123         /* insert the node into the rbtree */
 124         rb_link_node(&rbnode->node, parent, new);
 125         rb_insert_color(&rbnode->node, root);
 126
 127         return 1;
 128 }
 129
 130 #ifdef CONFIG_DEBUG_FS
 131 static int rbtree_show(struct seq_file *s, void *ignored)
 132 {
 133         struct regmap *map = s->private;
 134         struct regcache_rbtree_ctx *rbtree_ctx = map->cache;
 135         struct regcache_rbtree_node *n;
 136         struct rb_node *node;
 137         unsigned int base, top;
 138         int nodes = 0;
 139         int registers = 0;
 140
 141         mutex_lock(&map->lock);
 142
 143         for (node = rb_first(&rbtree_ctx->root); node != NULL;
 144              node = rb_next(node)) {
 145                 n = container_of(node, struct regcache_rbtree_node, node);
 146
 147                 regcache_rbtree_get_base_top_reg(n, &base, &top);
 148                 seq_printf(s, "%x-%x (%d)\n", base, top, top - base + 1);
 149
 150                 nodes++;
 151                 registers += top - base + 1;
 152         }
 153
 154         seq_printf(s, "%d nodes, %d registers, average %d registers\n",
 155                    nodes, registers, registers / nodes);
 156
 157         mutex_unlock(&map->lock);
 158
 159         return 0;
 160 }
 161
 162 static int rbtree_open(struct inode *inode, struct file *file)
 163 {
 164         return single_open(file, rbtree_show, inode->i_private);
 165 }
 166
 167 static const struct file_operations rbtree_fops = {
 168         .open           = rbtree_open,
 169         .read           = seq_read,
 170         .llseek         = seq_lseek,
 171         .release        = single_release,
 172 };
 173
 174 static void rbtree_debugfs_init(struct regmap *map)
 175 {
 176         debugfs_create_file("rbtree", 0400, map->debugfs, map, &rbtree_fops);
 177 }
 178 #else
 179 static void rbtree_debugfs_init(struct regmap *map)
 180 {
 181 }
 182 #endif
 183
 184 static int regcache_rbtree_init(struct regmap *map)
 185 {
 186         struct regcache_rbtree_ctx *rbtree_ctx;
 187         int i;
 188         int ret;
 189
 190         map->cache = kmalloc(sizeof *rbtree_ctx, GFP_KERNEL);
 191         if (!map->cache)
 192                 return -ENOMEM;
 193
 194         rbtree_ctx = map->cache;
 195         rbtree_ctx->root = RB_ROOT;
 196         rbtree_ctx->cached_rbnode = NULL;
 197
 198         for (i = 0; i < map->num_reg_defaults; i++) {
 199                 ret = regcache_rbtree_write(map,
 200                                             map->reg_defaults[i].reg,
 201                                             map->reg_defaults[i].def);
 202                 if (ret)
 203                         goto err;
 204         }
 205
 206         rbtree_debugfs_init(map);
 207
 208         return 0;
 209
 210 err:
 211         regcache_rbtree_exit(map);
 212         return ret;
 213 }
 214
 215 static int regcache_rbtree_exit(struct regmap *map)
 216 {
 217         struct rb_node *next;
 218         struct regcache_rbtree_ctx *rbtree_ctx;
 219         struct regcache_rbtree_node *rbtree_node;
 220
 221         /* if we've already been called then just return */
 222         rbtree_ctx = map->cache;
 223         if (!rbtree_ctx)
 224                 return 0;
 225
 226         /* free up the rbtree */
 227         next = rb_first(&rbtree_ctx->root);
 228         while (next) {
 229                 rbtree_node = rb_entry(next, struct regcache_rbtree_node, node);
 230                 next = rb_next(&rbtree_node->node);
 231                 rb_erase(&rbtree_node->node, &rbtree_ctx->root);
 232                 kfree(rbtree_node->block);
 233                 kfree(rbtree_node);
 234         }
 235
 236         /* release the resources */
 237         kfree(map->cache);
 238         map->cache = NULL;
 239
 240         return 0;
 241 }
 242
 243 static int regcache_rbtree_read(struct regmap *map,
 244                                 unsigned int reg, unsigned int *value)
 245 {
 246         struct regcache_rbtree_node *rbnode;
 247         unsigned int reg_tmp;
 248
 249         rbnode = regcache_rbtree_lookup(map, reg);
 250         if (rbnode) {
 251                 reg_tmp = reg - rbnode->base_reg;
 252                 *value = regcache_rbtree_get_register(rbnode, reg_tmp,
 253                                                       map->cache_word_size);
 254         } else {
 255                 return -ENOENT;
 256         }
 257
 258         return 0;
 259 }
 260
 261
 262 static int regcache_rbtree_insert_to_block(struct regcache_rbtree_node *rbnode,
 263                                            unsigned int pos, unsigned int reg,
 264                                            unsigned int value, unsigned int word_size)
 265 {
 266         u8 *blk;
 267
 268         blk = krealloc(rbnode->block,
 269                        (rbnode->blklen + 1) * word_size, GFP_KERNEL);
 270         if (!blk)
 271                 return -ENOMEM;
 272
 273         /* insert the register value in the correct place in the rbnode block */
 274         memmove(blk + (pos + 1) * word_size,
 275                 blk + pos * word_size,
 276                 (rbnode->blklen - pos) * word_size);
 277
 278         /* update the rbnode block, its size and the base register */
 279         rbnode->block = blk;
 280         rbnode->blklen++;
 281         if (!pos)
 282                 rbnode->base_reg = reg;
 283
 284         regcache_rbtree_set_register(rbnode, pos, value, word_size);
 285         return 0;
 286 }
 287
 288 static int regcache_rbtree_write(struct regmap *map, unsigned int reg,
 289                                  unsigned int value)
 290 {
 291         struct regcache_rbtree_ctx *rbtree_ctx;
 292         struct regcache_rbtree_node *rbnode, *rbnode_tmp;
 293         struct rb_node *node;
 294         unsigned int val;
 295         unsigned int reg_tmp;
 296         unsigned int pos;
 297         int i;
 298         int ret;
 299
 300         rbtree_ctx = map->cache;
 301         /* if we can't locate it in the cached rbnode we'll have
 302          * to traverse the rbtree looking for it.
 303          */
 304         rbnode = regcache_rbtree_lookup(map, reg);
 305         if (rbnode) {
 306                 reg_tmp = reg - rbnode->base_reg;
 307                 val = regcache_rbtree_get_register(rbnode, reg_tmp,
 308                                                    map->cache_word_size);
 309                 if (val == value)
 310                         return 0;
 311                 regcache_rbtree_set_register(rbnode, reg_tmp, value,
 312                                              map->cache_word_size);
 313         } else {
 314                 /* look for an adjacent register to the one we are about to add */
 315                 for (node = rb_first(&rbtree_ctx->root); node;
 316                      node = rb_next(node)) {
 317                         rbnode_tmp = rb_entry(node, struct regcache_rbtree_node, node);
 318                         for (i = 0; i < rbnode_tmp->blklen; i++) {
 319                                 reg_tmp = rbnode_tmp->base_reg + i;
 320                                 if (abs(reg_tmp - reg) != 1)
 321                                         continue;
 322                                 /* decide where in the block to place our register */
 323                                 if (reg_tmp + 1 == reg)
 324                                         pos = i + 1;
 325                                 else
 326                                         pos = i;
 327                                 ret = regcache_rbtree_insert_to_block(rbnode_tmp, pos,
 328                                                                       reg, value,
 329                                                                       map->cache_word_size);
 330                                 if (ret)
 331                                         return ret;
 332                                 rbtree_ctx->cached_rbnode = rbnode_tmp;
 333                                 return 0;
 334                         }
 335                 }
 336                 /* we did not manage to find a place to insert it in an existing
 337                  * block so create a new rbnode with a single register in its block.
 338                  * This block will get populated further if any other adjacent
 339                  * registers get modified in the future.
 340                  */
 341                 rbnode = kzalloc(sizeof *rbnode, GFP_KERNEL);
 342                 if (!rbnode)
 343                         return -ENOMEM;
 344                 rbnode->blklen = 1;
 345                 rbnode->base_reg = reg;
 346                 rbnode->block = kmalloc(rbnode->blklen * map->cache_word_size,
 347                                         GFP_KERNEL);
 348                 if (!rbnode->block) {
 349                         kfree(rbnode);
 350                         return -ENOMEM;
 351                 }
 352                 regcache_rbtree_set_register(rbnode, 0, value, map->cache_word_size);
 353                 regcache_rbtree_insert(&rbtree_ctx->root, rbnode);
 354                 rbtree_ctx->cached_rbnode = rbnode;
 355         }
 356
 357         return 0;
 358 }
 359
 360 static int regcache_rbtree_sync(struct regmap *map)
 361 {
 362         struct regcache_rbtree_ctx *rbtree_ctx;
 363         struct rb_node *node;
 364         struct regcache_rbtree_node *rbnode;
 365         unsigned int regtmp;
 366         unsigned int val;
 367         int ret;
 368         int i;
 369
 370         rbtree_ctx = map->cache;
 371         for (node = rb_first(&rbtree_ctx->root); node; node = rb_next(node)) {
 372                 rbnode = rb_entry(node, struct regcache_rbtree_node, node);
 373                 for (i = 0; i < rbnode->blklen; i++) {
 374                         regtmp = rbnode->base_reg + i;
 375                         val = regcache_rbtree_get_register(rbnode, i,
 376                                                            map->cache_word_size);
 377
 378                         /* Is this the hardware default?  If so skip. */
 379                         ret = regcache_lookup_reg(map, i);
 380                         if (ret > 0 && val == map->reg_defaults[ret].def)
 381                                 continue;
 382
 383                         map->cache_bypass = 1;
 384                         ret = _regmap_write(map, regtmp, val);
 385                         map->cache_bypass = 0;
 386                         if (ret)
 387                                 return ret;
 388                         dev_dbg(map->dev, "Synced register %#x, value %#x\n",
 389                                 regtmp, val);
 390                 }
 391         }
 392
 393         return 0;
 394 }
 395
 396 struct regcache_ops regcache_rbtree_ops = {
 397         .type = REGCACHE_RBTREE,
 398         .name = "rbtree",
 399         .init = regcache_rbtree_init,
 400         .exit = regcache_rbtree_exit,
 401         .read = regcache_rbtree_read,
 402         .write = regcache_rbtree_write,
 403         .sync = regcache_rbtree_sync
 404 };