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         int nodes = 0;
 142         int registers = 0;
 143         int this_registers, average;
 144
 145         map->lock(map);
 146
 147         for (node = rb_first(&rbtree_ctx->root); node != NULL;
 148              node = rb_next(node)) {
 149                 n = container_of(node, struct regcache_rbtree_node, node);
 150
 151                 regcache_rbtree_get_base_top_reg(map, n, &base, &top);
 152                 this_registers = ((top - base) / map->reg_stride) + 1;
 153                 seq_printf(s, "%x-%x (%d)\n", base, top, this_registers);
 154
 155                 nodes++;
 156                 registers += this_registers;
 157         }
 158
 159         if (nodes)
 160                 average = registers / nodes;
 161         else
 162                 average = 0;
 163
 164         seq_printf(s, "%d nodes, %d registers, average %d registers\n",
 165                    nodes, registers, average);
 166
 167         map->unlock(map);
 168
 169         return 0;
 170 }
 171
 172 static int rbtree_open(struct inode *inode, struct file *file)
 173 {
 174         return single_open(file, rbtree_show, inode->i_private);
 175 }
 176
 177 static const struct file_operations rbtree_fops = {
 178         .open           = rbtree_open,
 179         .read           = seq_read,
 180         .llseek         = seq_lseek,
 181         .release        = single_release,
 182 };
 183
 184 static void rbtree_debugfs_init(struct regmap *map)
 185 {
 186         debugfs_create_file("rbtree", 0400, map->debugfs, map, &rbtree_fops);
 187 }
 188 #else
 189 static void rbtree_debugfs_init(struct regmap *map)
 190 {
 191 }
 192 #endif
 193
 194 static int regcache_rbtree_init(struct regmap *map)
 195 {
 196         struct regcache_rbtree_ctx *rbtree_ctx;
 197         int i;
 198         int ret;
 199
 200         map->cache = kmalloc(sizeof *rbtree_ctx, GFP_KERNEL);
 201         if (!map->cache)
 202                 return -ENOMEM;
 203
 204         rbtree_ctx = map->cache;
 205         rbtree_ctx->root = RB_ROOT;
 206         rbtree_ctx->cached_rbnode = NULL;
 207
 208         for (i = 0; i < map->num_reg_defaults; i++) {
 209                 ret = regcache_rbtree_write(map,
 210                                             map->reg_defaults[i].reg,
 211                                             map->reg_defaults[i].def);
 212                 if (ret)
 213                         goto err;
 214         }
 215
 216         rbtree_debugfs_init(map);
 217
 218         return 0;
 219
 220 err:
 221         regcache_rbtree_exit(map);
 222         return ret;
 223 }
 224
 225 static int regcache_rbtree_exit(struct regmap *map)
 226 {
 227         struct rb_node *next;
 228         struct regcache_rbtree_ctx *rbtree_ctx;
 229         struct regcache_rbtree_node *rbtree_node;
 230
 231         /* if we've already been called then just return */
 232         rbtree_ctx = map->cache;
 233         if (!rbtree_ctx)
 234                 return 0;
 235
 236         /* free up the rbtree */
 237         next = rb_first(&rbtree_ctx->root);
 238         while (next) {
 239                 rbtree_node = rb_entry(next, struct regcache_rbtree_node, node);
 240                 next = rb_next(&rbtree_node->node);
 241                 rb_erase(&rbtree_node->node, &rbtree_ctx->root);
 242                 kfree(rbtree_node->block);
 243                 kfree(rbtree_node);
 244         }
 245
 246         /* release the resources */
 247         kfree(map->cache);
 248         map->cache = NULL;
 249
 250         return 0;
 251 }
 252
 253 static int regcache_rbtree_read(struct regmap *map,
 254                                 unsigned int reg, unsigned int *value)
 255 {
 256         struct regcache_rbtree_node *rbnode;
 257         unsigned int reg_tmp;
 258
 259         rbnode = regcache_rbtree_lookup(map, reg);
 260         if (rbnode) {
 261                 reg_tmp = (reg - rbnode->base_reg) / map->reg_stride;
 262                 *value = regcache_rbtree_get_register(map, rbnode, reg_tmp);
 263         } else {
 264                 return -ENOENT;
 265         }
 266
 267         return 0;
 268 }
 269
 270
 271 static int regcache_rbtree_insert_to_block(struct regmap *map,
 272                                            struct regcache_rbtree_node *rbnode,
 273                                            unsigned int pos, unsigned int reg,
 274                                            unsigned int value)
 275 {
 276         u8 *blk;
 277
 278         blk = krealloc(rbnode->block,
 279                        (rbnode->blklen + 1) * map->cache_word_size,
 280                        GFP_KERNEL);
 281         if (!blk)
 282                 return -ENOMEM;
 283
 284         /* insert the register value in the correct place in the rbnode block */
 285         memmove(blk + (pos + 1) * map->cache_word_size,
 286                 blk + pos * map->cache_word_size,
 287                 (rbnode->blklen - pos) * map->cache_word_size);
 288
 289         /* update the rbnode block, its size and the base register */
 290         rbnode->block = blk;
 291         rbnode->blklen++;
 292         if (!pos)
 293                 rbnode->base_reg = reg;
 294
 295         regcache_rbtree_set_register(map, rbnode, pos, value);
 296         return 0;
 297 }
 298
 299 static int regcache_rbtree_write(struct regmap *map, unsigned int reg,
 300                                  unsigned int value)
 301 {
 302         struct regcache_rbtree_ctx *rbtree_ctx;
 303         struct regcache_rbtree_node *rbnode, *rbnode_tmp;
 304         struct rb_node *node;
 305         unsigned int reg_tmp;
 306         unsigned int pos;
 307         int i;
 308         int ret;
 309
 310         rbtree_ctx = map->cache;
 311         /* if we can't locate it in the cached rbnode we'll have
 312          * to traverse the rbtree looking for it.
 313          */
 314         rbnode = regcache_rbtree_lookup(map, reg);
 315         if (rbnode) {
 316                 reg_tmp = (reg - rbnode->base_reg) / map->reg_stride;
 317                 regcache_rbtree_set_register(map, rbnode, reg_tmp, value);
 318         } else {
 319                 /* look for an adjacent register to the one we are about to add */
 320                 for (node = rb_first(&rbtree_ctx->root); node;
 321                      node = rb_next(node)) {
 322                         rbnode_tmp = rb_entry(node, struct regcache_rbtree_node,
 323                                               node);
 324                         for (i = 0; i < rbnode_tmp->blklen; i++) {
 325                                 reg_tmp = rbnode_tmp->base_reg +
 326                                                 (i * map->reg_stride);
 327                                 if (abs(reg_tmp - reg) != map->reg_stride)
 328                                         continue;
 329                                 /* decide where in the block to place our register */
 330                                 if (reg_tmp + map->reg_stride == reg)
 331                                         pos = i + 1;
 332                                 else
 333                                         pos = i;
 334                                 ret = regcache_rbtree_insert_to_block(map,
 335                                                                       rbnode_tmp,
 336                                                                       pos, reg,
 337                                                                       value);
 338                                 if (ret)
 339                                         return ret;
 340                                 rbtree_ctx->cached_rbnode = rbnode_tmp;
 341                                 return 0;
 342                         }
 343                 }
 344                 /* we did not manage to find a place to insert it in an existing
 345                  * block so create a new rbnode with a single register in its block.
 346                  * This block will get populated further if any other adjacent
 347                  * registers get modified in the future.
 348                  */
 349                 rbnode = kzalloc(sizeof *rbnode, GFP_KERNEL);
 350                 if (!rbnode)
 351                         return -ENOMEM;
 352                 rbnode->blklen = 1;
 353                 rbnode->base_reg = reg;
 354                 rbnode->block = kmalloc(rbnode->blklen * map->cache_word_size,
 355                                         GFP_KERNEL);
 356                 if (!rbnode->block) {
 357                         kfree(rbnode);
 358                         return -ENOMEM;
 359                 }
 360                 regcache_rbtree_set_register(map, rbnode, 0, value);
 361                 regcache_rbtree_insert(map, &rbtree_ctx->root, rbnode);
 362                 rbtree_ctx->cached_rbnode = rbnode;
 363         }
 364
 365         return 0;
 366 }
 367
 368 static int regcache_rbtree_sync(struct regmap *map, unsigned int min,
 369                                 unsigned int max)
 370 {
 371         struct regcache_rbtree_ctx *rbtree_ctx;
 372         struct rb_node *node;
 373         struct regcache_rbtree_node *rbnode;
 374         unsigned int regtmp;
 375         unsigned int val;
 376         int ret;
 377         int i, base, end;
 378
 379         rbtree_ctx = map->cache;
 380         for (node = rb_first(&rbtree_ctx->root); node; node = rb_next(node)) {
 381                 rbnode = rb_entry(node, struct regcache_rbtree_node, node);
 382
 383                 if (rbnode->base_reg < min)
 384                         continue;
 385                 if (rbnode->base_reg > max)
 386                         break;
 387                 if (rbnode->base_reg + rbnode->blklen < min)
 388                         continue;
 389
 390                 if (min > rbnode->base_reg)
 391                         base = min - rbnode->base_reg;
 392                 else
 393                         base = 0;
 394
 395                 if (max < rbnode->base_reg + rbnode->blklen)
 396                         end = rbnode->base_reg + rbnode->blklen - max;
 397                 else
 398                         end = rbnode->blklen;
 399
 400                 for (i = base; i < end; i++) {
 401                         regtmp = rbnode->base_reg + (i * map->reg_stride);
 402                         val = regcache_rbtree_get_register(map, rbnode, i);
 403
 404                         /* Is this the hardware default?  If so skip. */
 405                         ret = regcache_lookup_reg(map, regtmp);
 406                         if (ret >= 0 && val == map->reg_defaults[ret].def)
 407                                 continue;
 408
 409                         map->cache_bypass = 1;
 410                         ret = _regmap_write(map, regtmp, val);
 411                         map->cache_bypass = 0;
 412                         if (ret)
 413                                 return ret;
 414                         dev_dbg(map->dev, "Synced register %#x, value %#x\n",
 415                                 regtmp, val);
 416                 }
 417         }
 418
 419         return 0;
 420 }
 421
 422 struct regcache_ops regcache_rbtree_ops = {
 423         .type = REGCACHE_RBTREE,
 424         .name = "rbtree",
 425         .init = regcache_rbtree_init,
 426         .exit = regcache_rbtree_exit,
 427         .read = regcache_rbtree_read,
 428         .write = regcache_rbtree_write,
 429         .sync = regcache_rbtree_sync
 430 };