drivers/base/regmap/regcache-maple.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 //
   3 // Register cache access API - maple tree based cache
   4 //
   5 // Copyright 2023 Arm, Ltd
   6 //
   7 // Author: Mark Brown <broonie@kernel.org>
   8
   9 #include <linux/debugfs.h>
  10 #include <linux/device.h>
  11 #include <linux/maple_tree.h>
  12 #include <linux/slab.h>
  13
  14 #include "internal.h"
  15
  16 static int regcache_maple_read(struct regmap *map,
  17                                unsigned int reg, unsigned int *value)
  18 {
  19         struct maple_tree *mt = map->cache;
  20         MA_STATE(mas, mt, reg, reg);
  21         unsigned long *entry;
  22
  23         rcu_read_lock();
  24
  25         entry = mas_walk(&mas);
  26         if (!entry) {
  27                 rcu_read_unlock();
  28                 return -ENOENT;
  29         }
  30
  31         *value = entry[reg - mas.index];
  32
  33         rcu_read_unlock();
  34
  35         return 0;
  36 }
  37
  38 static int regcache_maple_write(struct regmap *map, unsigned int reg,
  39                                 unsigned int val)
  40 {
  41         struct maple_tree *mt = map->cache;
  42         MA_STATE(mas, mt, reg, reg);
  43         unsigned long *entry, *upper, *lower;
  44         unsigned long index, last;
  45         size_t lower_sz, upper_sz;
  46         int ret;
  47
  48         rcu_read_lock();
  49
  50         entry = mas_walk(&mas);
  51         if (entry) {
  52                 entry[reg - mas.index] = val;
  53                 rcu_read_unlock();
  54                 return 0;
  55         }
  56
  57         /* Any adjacent entries to extend/merge? */
  58         mas_set_range(&mas, reg - 1, reg + 1);
  59         index = reg;
  60         last = reg;
  61
  62         lower = mas_find(&mas, reg - 1);
  63         if (lower) {
  64                 index = mas.index;
  65                 lower_sz = (mas.last - mas.index + 1) * sizeof(unsigned long);
  66         }
  67
  68         upper = mas_find(&mas, reg + 1);
  69         if (upper) {
  70                 last = mas.last;
  71                 upper_sz = (mas.last - mas.index + 1) * sizeof(unsigned long);
  72         }
  73
  74         rcu_read_unlock();
  75
  76         entry = kmalloc((last - index + 1) * sizeof(unsigned long),
  77                         map->alloc_flags);
  78         if (!entry)
  79                 return -ENOMEM;
  80
  81         if (lower)
  82                 memcpy(entry, lower, lower_sz);
  83         entry[reg - index] = val;
  84         if (upper)
  85                 memcpy(&entry[reg - index + 1], upper, upper_sz);
  86
  87         /*
  88          * This is safe because the regmap lock means the Maple lock
  89          * is redundant, but we need to take it due to lockdep asserts
  90          * in the maple tree code.
  91          */
  92         mas_lock(&mas);
  93
  94         mas_set_range(&mas, index, last);
  95         ret = mas_store_gfp(&mas, entry, map->alloc_flags);
  96
  97         mas_unlock(&mas);
  98
  99         if (ret == 0) {
 100                 kfree(lower);
 101                 kfree(upper);
 102         }
 103
 104         return ret;
 105 }
 106
 107 static int regcache_maple_drop(struct regmap *map, unsigned int min,
 108                                unsigned int max)
 109 {
 110         struct maple_tree *mt = map->cache;
 111         MA_STATE(mas, mt, min, max);
 112         unsigned long *entry, *lower, *upper;
 113         /* initialized to work around false-positive -Wuninitialized warning */
 114         unsigned long lower_index = 0, lower_last = 0;
 115         unsigned long upper_index, upper_last;
 116         int ret = 0;
 117
 118         lower = NULL;
 119         upper = NULL;
 120
 121         mas_lock(&mas);
 122
 123         mas_for_each(&mas, entry, max) {
 124                 /*
 125                  * This is safe because the regmap lock means the
 126                  * Maple lock is redundant, but we need to take it due
 127                  * to lockdep asserts in the maple tree code.
 128                  */
 129                 mas_unlock(&mas);
 130
 131                 /* Do we need to save any of this entry? */
 132                 if (mas.index < min) {
 133                         lower_index = mas.index;
 134                         lower_last = min -1;
 135
 136                         lower = kmemdup_array(entry,
 137                                               min - mas.index, sizeof(*lower),
 138                                               map->alloc_flags);
 139                         if (!lower) {
 140                                 ret = -ENOMEM;
 141                                 goto out_unlocked;
 142                         }
 143                 }
 144
 145                 if (mas.last > max) {
 146                         upper_index = max + 1;
 147                         upper_last = mas.last;
 148
 149                         upper = kmemdup_array(&entry[max - mas.index + 1],
 150                                               mas.last - max, sizeof(*upper),
 151                                               map->alloc_flags);
 152                         if (!upper) {
 153                                 ret = -ENOMEM;
 154                                 goto out_unlocked;
 155                         }
 156                 }
 157
 158                 kfree(entry);
 159                 mas_lock(&mas);
 160                 mas_erase(&mas);
 161
 162                 /* Insert new nodes with the saved data */
 163                 if (lower) {
 164                         mas_set_range(&mas, lower_index, lower_last);
 165                         ret = mas_store_gfp(&mas, lower, map->alloc_flags);
 166                         if (ret != 0)
 167                                 goto out;
 168                         lower = NULL;
 169                 }
 170
 171                 if (upper) {
 172                         mas_set_range(&mas, upper_index, upper_last);
 173                         ret = mas_store_gfp(&mas, upper, map->alloc_flags);
 174                         if (ret != 0)
 175                                 goto out;
 176                         upper = NULL;
 177                 }
 178         }
 179
 180 out:
 181         mas_unlock(&mas);
 182 out_unlocked:
 183         kfree(lower);
 184         kfree(upper);
 185
 186         return ret;
 187 }
 188
 189 static int regcache_maple_sync_block(struct regmap *map, unsigned long *entry,
 190                                      struct ma_state *mas,
 191                                      unsigned int min, unsigned int max)
 192 {
 193         void *buf;
 194         unsigned long r;
 195         size_t val_bytes = map->format.val_bytes;
 196         int ret = 0;
 197
 198         mas_pause(mas);
 199         rcu_read_unlock();
 200
 201         /*
 202          * Use a raw write if writing more than one register to a
 203          * device that supports raw writes to reduce transaction
 204          * overheads.
 205          */
 206         if (max - min > 1 && regmap_can_raw_write(map)) {
 207                 buf = kmalloc(val_bytes * (max - min), map->alloc_flags);
 208                 if (!buf) {
 209                         ret = -ENOMEM;
 210                         goto out;
 211                 }
 212
 213                 /* Render the data for a raw write */
 214                 for (r = min; r < max; r++) {
 215                         regcache_set_val(map, buf, r - min,
 216                                          entry[r - mas->index]);
 217                 }
 218
 219                 ret = _regmap_raw_write(map, min, buf, (max - min) * val_bytes,
 220                                         false);
 221
 222                 kfree(buf);
 223         } else {
 224                 for (r = min; r < max; r++) {
 225                         ret = _regmap_write(map, r,
 226                                             entry[r - mas->index]);
 227                         if (ret != 0)
 228                                 goto out;
 229                 }
 230         }
 231
 232 out:
 233         rcu_read_lock();
 234
 235         return ret;
 236 }
 237
 238 static int regcache_maple_sync(struct regmap *map, unsigned int min,
 239                                unsigned int max)
 240 {
 241         struct maple_tree *mt = map->cache;
 242         unsigned long *entry;
 243         MA_STATE(mas, mt, min, max);
 244         unsigned long lmin = min;
 245         unsigned long lmax = max;
 246         unsigned int r, v, sync_start;
 247         int ret = 0;
 248         bool sync_needed = false;
 249
 250         map->cache_bypass = true;
 251
 252         rcu_read_lock();
 253
 254         mas_for_each(&mas, entry, max) {
 255                 for (r = max(mas.index, lmin); r <= min(mas.last, lmax); r++) {
 256                         v = entry[r - mas.index];
 257
 258                         if (regcache_reg_needs_sync(map, r, v)) {
 259                                 if (!sync_needed) {
 260                                         sync_start = r;
 261                                         sync_needed = true;
 262                                 }
 263                                 continue;
 264                         }
 265
 266                         if (!sync_needed)
 267                                 continue;
 268
 269                         ret = regcache_maple_sync_block(map, entry, &mas,
 270                                                         sync_start, r);
 271                         if (ret != 0)
 272                                 goto out;
 273                         sync_needed = false;
 274                 }
 275
 276                 if (sync_needed) {
 277                         ret = regcache_maple_sync_block(map, entry, &mas,
 278                                                         sync_start, r);
 279                         if (ret != 0)
 280                                 goto out;
 281                         sync_needed = false;
 282                 }
 283         }
 284
 285 out:
 286         rcu_read_unlock();
 287
 288         map->cache_bypass = false;
 289
 290         return ret;
 291 }
 292
 293 static int regcache_maple_exit(struct regmap *map)
 294 {
 295         struct maple_tree *mt = map->cache;
 296         MA_STATE(mas, mt, 0, UINT_MAX);
 297         unsigned int *entry;
 298
 299         /* if we've already been called then just return */
 300         if (!mt)
 301                 return 0;
 302
 303         mas_lock(&mas);
 304         mas_for_each(&mas, entry, UINT_MAX)
 305                 kfree(entry);
 306         __mt_destroy(mt);
 307         mas_unlock(&mas);
 308
 309         kfree(mt);
 310         map->cache = NULL;
 311
 312         return 0;
 313 }
 314
 315 static int regcache_maple_insert_block(struct regmap *map, int first,
 316                                         int last)
 317 {
 318         struct maple_tree *mt = map->cache;
 319         MA_STATE(mas, mt, first, last);
 320         unsigned long *entry;
 321         int i, ret;
 322
 323         entry = kcalloc(last - first + 1, sizeof(unsigned long), map->alloc_flags);
 324         if (!entry)
 325                 return -ENOMEM;
 326
 327         for (i = 0; i < last - first + 1; i++)
 328                 entry[i] = map->reg_defaults[first + i].def;
 329
 330         mas_lock(&mas);
 331
 332         mas_set_range(&mas, map->reg_defaults[first].reg,
 333                       map->reg_defaults[last].reg);
 334         ret = mas_store_gfp(&mas, entry, map->alloc_flags);
 335
 336         mas_unlock(&mas);
 337
 338         if (ret)
 339                 kfree(entry);
 340
 341         return ret;
 342 }
 343
 344 static int regcache_maple_init(struct regmap *map)
 345 {
 346         struct maple_tree *mt;
 347         int i;
 348         int ret;
 349         int range_start;
 350
 351         mt = kmalloc(sizeof(*mt), map->alloc_flags);
 352         if (!mt)
 353                 return -ENOMEM;
 354         map->cache = mt;
 355
 356         mt_init(mt);
 357
 358         if (!mt_external_lock(mt) && map->lock_key)
 359                 lockdep_set_class_and_subclass(&mt->ma_lock, map->lock_key, 1);
 360
 361         if (!map->num_reg_defaults)
 362                 return 0;
 363
 364         range_start = 0;
 365
 366         /* Scan for ranges of contiguous registers */
 367         for (i = 1; i < map->num_reg_defaults; i++) {
 368                 if (map->reg_defaults[i].reg !=
 369                     map->reg_defaults[i - 1].reg + 1) {
 370                         ret = regcache_maple_insert_block(map, range_start,
 371                                                           i - 1);
 372                         if (ret != 0)
 373                                 goto err;
 374
 375                         range_start = i;
 376                 }
 377         }
 378
 379         /* Add the last block */
 380         ret = regcache_maple_insert_block(map, range_start,
 381                                           map->num_reg_defaults - 1);
 382         if (ret != 0)
 383                 goto err;
 384
 385         return 0;
 386
 387 err:
 388         regcache_maple_exit(map);
 389         return ret;
 390 }
 391
 392 struct regcache_ops regcache_maple_ops = {
 393         .type = REGCACHE_MAPLE,
 394         .name = "maple",
 395         .init = regcache_maple_init,
 396         .exit = regcache_maple_exit,
 397         .read = regcache_maple_read,
 398         .write = regcache_maple_write,
 399         .drop = regcache_maple_drop,
 400         .sync = regcache_maple_sync,
 401 };