drivers/base/regmap/regcache-lzo.c

   1 /*
   2  * Register cache access API - LZO 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/device.h>
  14 #include <linux/lzo.h>
  15 #include <linux/slab.h>
  16
  17 #include "internal.h"
  18
  19 static int regcache_lzo_exit(struct regmap *map);
  20
  21 struct regcache_lzo_ctx {
  22         void *wmem;
  23         void *dst;
  24         const void *src;
  25         size_t src_len;
  26         size_t dst_len;
  27         size_t decompressed_size;
  28         unsigned long *sync_bmp;
  29         int sync_bmp_nbits;
  30 };
  31
  32 #define LZO_BLOCK_NUM 8
  33 static int regcache_lzo_block_count(struct regmap *map)
  34 {
  35         return LZO_BLOCK_NUM;
  36 }
  37
  38 static int regcache_lzo_prepare(struct regcache_lzo_ctx *lzo_ctx)
  39 {
  40         lzo_ctx->wmem = kmalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
  41         if (!lzo_ctx->wmem)
  42                 return -ENOMEM;
  43         return 0;
  44 }
  45
  46 static int regcache_lzo_compress(struct regcache_lzo_ctx *lzo_ctx)
  47 {
  48         size_t compress_size;
  49         int ret;
  50
  51         ret = lzo1x_1_compress(lzo_ctx->src, lzo_ctx->src_len,
  52                                lzo_ctx->dst, &compress_size, lzo_ctx->wmem);
  53         if (ret != LZO_E_OK || compress_size > lzo_ctx->dst_len)
  54                 return -EINVAL;
  55         lzo_ctx->dst_len = compress_size;
  56         return 0;
  57 }
  58
  59 static int regcache_lzo_decompress(struct regcache_lzo_ctx *lzo_ctx)
  60 {
  61         size_t dst_len;
  62         int ret;
  63
  64         dst_len = lzo_ctx->dst_len;
  65         ret = lzo1x_decompress_safe(lzo_ctx->src, lzo_ctx->src_len,
  66                                     lzo_ctx->dst, &dst_len);
  67         if (ret != LZO_E_OK || dst_len != lzo_ctx->dst_len)
  68                 return -EINVAL;
  69         return 0;
  70 }
  71
  72 static int regcache_lzo_compress_cache_block(struct regmap *map,
  73                 struct regcache_lzo_ctx *lzo_ctx)
  74 {
  75         int ret;
  76
  77         lzo_ctx->dst_len = lzo1x_worst_compress(PAGE_SIZE);
  78         lzo_ctx->dst = kmalloc(lzo_ctx->dst_len, GFP_KERNEL);
  79         if (!lzo_ctx->dst) {
  80                 lzo_ctx->dst_len = 0;
  81                 return -ENOMEM;
  82         }
  83
  84         ret = regcache_lzo_compress(lzo_ctx);
  85         if (ret < 0)
  86                 return ret;
  87         return 0;
  88 }
  89
  90 static int regcache_lzo_decompress_cache_block(struct regmap *map,
  91                 struct regcache_lzo_ctx *lzo_ctx)
  92 {
  93         int ret;
  94
  95         lzo_ctx->dst_len = lzo_ctx->decompressed_size;
  96         lzo_ctx->dst = kmalloc(lzo_ctx->dst_len, GFP_KERNEL);
  97         if (!lzo_ctx->dst) {
  98                 lzo_ctx->dst_len = 0;
  99                 return -ENOMEM;
 100         }
 101
 102         ret = regcache_lzo_decompress(lzo_ctx);
 103         if (ret < 0)
 104                 return ret;
 105         return 0;
 106 }
 107
 108 static inline int regcache_lzo_get_blkindex(struct regmap *map,
 109                                             unsigned int reg)
 110 {
 111         return ((reg / map->reg_stride) * map->cache_word_size) /
 112                 DIV_ROUND_UP(map->cache_size_raw,
 113                              regcache_lzo_block_count(map));
 114 }
 115
 116 static inline int regcache_lzo_get_blkpos(struct regmap *map,
 117                                           unsigned int reg)
 118 {
 119         return (reg / map->reg_stride) %
 120                     (DIV_ROUND_UP(map->cache_size_raw,
 121                                   regcache_lzo_block_count(map)) /
 122                      map->cache_word_size);
 123 }
 124
 125 static inline int regcache_lzo_get_blksize(struct regmap *map)
 126 {
 127         return DIV_ROUND_UP(map->cache_size_raw,
 128                             regcache_lzo_block_count(map));
 129 }
 130
 131 static int regcache_lzo_init(struct regmap *map)
 132 {
 133         struct regcache_lzo_ctx **lzo_blocks;
 134         size_t bmp_size;
 135         int ret, i, blksize, blkcount;
 136         const char *p, *end;
 137         unsigned long *sync_bmp;
 138
 139         ret = 0;
 140
 141         blkcount = regcache_lzo_block_count(map);
 142         map->cache = kzalloc(blkcount * sizeof *lzo_blocks,
 143                              GFP_KERNEL);
 144         if (!map->cache)
 145                 return -ENOMEM;
 146         lzo_blocks = map->cache;
 147
 148         /*
 149          * allocate a bitmap to be used when syncing the cache with
 150          * the hardware.  Each time a register is modified, the corresponding
 151          * bit is set in the bitmap, so we know that we have to sync
 152          * that register.
 153          */
 154         bmp_size = map->num_reg_defaults_raw;
 155         sync_bmp = kmalloc(BITS_TO_LONGS(bmp_size) * sizeof(long),
 156                            GFP_KERNEL);
 157         if (!sync_bmp) {
 158                 ret = -ENOMEM;
 159                 goto err;
 160         }
 161         bitmap_zero(sync_bmp, bmp_size);
 162
 163         /* allocate the lzo blocks and initialize them */
 164         for (i = 0; i < blkcount; i++) {
 165                 lzo_blocks[i] = kzalloc(sizeof **lzo_blocks,
 166                                         GFP_KERNEL);
 167                 if (!lzo_blocks[i]) {
 168                         kfree(sync_bmp);
 169                         ret = -ENOMEM;
 170                         goto err;
 171                 }
 172                 lzo_blocks[i]->sync_bmp = sync_bmp;
 173                 lzo_blocks[i]->sync_bmp_nbits = bmp_size;
 174                 /* alloc the working space for the compressed block */
 175                 ret = regcache_lzo_prepare(lzo_blocks[i]);
 176                 if (ret < 0)
 177                         goto err;
 178         }
 179
 180         blksize = regcache_lzo_get_blksize(map);
 181         p = map->reg_defaults_raw;
 182         end = map->reg_defaults_raw + map->cache_size_raw;
 183         /* compress the register map and fill the lzo blocks */
 184         for (i = 0; i < blkcount; i++, p += blksize) {
 185                 lzo_blocks[i]->src = p;
 186                 if (p + blksize > end)
 187                         lzo_blocks[i]->src_len = end - p;
 188                 else
 189                         lzo_blocks[i]->src_len = blksize;
 190                 ret = regcache_lzo_compress_cache_block(map,
 191                                                        lzo_blocks[i]);
 192                 if (ret < 0)
 193                         goto err;
 194                 lzo_blocks[i]->decompressed_size =
 195                         lzo_blocks[i]->src_len;
 196         }
 197
 198         return 0;
 199 err:
 200         regcache_lzo_exit(map);
 201         return ret;
 202 }
 203
 204 static int regcache_lzo_exit(struct regmap *map)
 205 {
 206         struct regcache_lzo_ctx **lzo_blocks;
 207         int i, blkcount;
 208
 209         lzo_blocks = map->cache;
 210         if (!lzo_blocks)
 211                 return 0;
 212
 213         blkcount = regcache_lzo_block_count(map);
 214         /*
 215          * the pointer to the bitmap used for syncing the cache
 216          * is shared amongst all lzo_blocks.  Ensure it is freed
 217          * only once.
 218          */
 219         if (lzo_blocks[0])
 220                 kfree(lzo_blocks[0]->sync_bmp);
 221         for (i = 0; i < blkcount; i++) {
 222                 if (lzo_blocks[i]) {
 223                         kfree(lzo_blocks[i]->wmem);
 224                         kfree(lzo_blocks[i]->dst);
 225                 }
 226                 /* each lzo_block is a pointer returned by kmalloc or NULL */
 227                 kfree(lzo_blocks[i]);
 228         }
 229         kfree(lzo_blocks);
 230         map->cache = NULL;
 231         return 0;
 232 }
 233
 234 static int regcache_lzo_read(struct regmap *map,
 235                              unsigned int reg, unsigned int *value)
 236 {
 237         struct regcache_lzo_ctx *lzo_block, **lzo_blocks;
 238         int ret, blkindex, blkpos;
 239         size_t blksize, tmp_dst_len;
 240         void *tmp_dst;
 241
 242         /* index of the compressed lzo block */
 243         blkindex = regcache_lzo_get_blkindex(map, reg);
 244         /* register index within the decompressed block */
 245         blkpos = regcache_lzo_get_blkpos(map, reg);
 246         /* size of the compressed block */
 247         blksize = regcache_lzo_get_blksize(map);
 248         lzo_blocks = map->cache;
 249         lzo_block = lzo_blocks[blkindex];
 250
 251         /* save the pointer and length of the compressed block */
 252         tmp_dst = lzo_block->dst;
 253         tmp_dst_len = lzo_block->dst_len;
 254
 255         /* prepare the source to be the compressed block */
 256         lzo_block->src = lzo_block->dst;
 257         lzo_block->src_len = lzo_block->dst_len;
 258
 259         /* decompress the block */
 260         ret = regcache_lzo_decompress_cache_block(map, lzo_block);
 261         if (ret >= 0)
 262                 /* fetch the value from the cache */
 263                 *value = regcache_get_val(map, lzo_block->dst, blkpos);
 264
 265         kfree(lzo_block->dst);
 266         /* restore the pointer and length of the compressed block */
 267         lzo_block->dst = tmp_dst;
 268         lzo_block->dst_len = tmp_dst_len;
 269
 270         return ret;
 271 }
 272
 273 static int regcache_lzo_write(struct regmap *map,
 274                               unsigned int reg, unsigned int value)
 275 {
 276         struct regcache_lzo_ctx *lzo_block, **lzo_blocks;
 277         int ret, blkindex, blkpos;
 278         size_t blksize, tmp_dst_len;
 279         void *tmp_dst;
 280
 281         /* index of the compressed lzo block */
 282         blkindex = regcache_lzo_get_blkindex(map, reg);
 283         /* register index within the decompressed block */
 284         blkpos = regcache_lzo_get_blkpos(map, reg);
 285         /* size of the compressed block */
 286         blksize = regcache_lzo_get_blksize(map);
 287         lzo_blocks = map->cache;
 288         lzo_block = lzo_blocks[blkindex];
 289
 290         /* save the pointer and length of the compressed block */
 291         tmp_dst = lzo_block->dst;
 292         tmp_dst_len = lzo_block->dst_len;
 293
 294         /* prepare the source to be the compressed block */
 295         lzo_block->src = lzo_block->dst;
 296         lzo_block->src_len = lzo_block->dst_len;
 297
 298         /* decompress the block */
 299         ret = regcache_lzo_decompress_cache_block(map, lzo_block);
 300         if (ret < 0) {
 301                 kfree(lzo_block->dst);
 302                 goto out;
 303         }
 304
 305         /* write the new value to the cache */
 306         if (regcache_set_val(map, lzo_block->dst, blkpos, value)) {
 307                 kfree(lzo_block->dst);
 308                 goto out;
 309         }
 310
 311         /* prepare the source to be the decompressed block */
 312         lzo_block->src = lzo_block->dst;
 313         lzo_block->src_len = lzo_block->dst_len;
 314
 315         /* compress the block */
 316         ret = regcache_lzo_compress_cache_block(map, lzo_block);
 317         if (ret < 0) {
 318                 kfree(lzo_block->dst);
 319                 kfree(lzo_block->src);
 320                 goto out;
 321         }
 322
 323         /* set the bit so we know we have to sync this register */
 324         set_bit(reg / map->reg_stride, lzo_block->sync_bmp);
 325         kfree(tmp_dst);
 326         kfree(lzo_block->src);
 327         return 0;
 328 out:
 329         lzo_block->dst = tmp_dst;
 330         lzo_block->dst_len = tmp_dst_len;
 331         return ret;
 332 }
 333
 334 static int regcache_lzo_sync(struct regmap *map, unsigned int min,
 335                              unsigned int max)
 336 {
 337         struct regcache_lzo_ctx **lzo_blocks;
 338         unsigned int val;
 339         int i;
 340         int ret;
 341
 342         lzo_blocks = map->cache;
 343         i = min;
 344         for_each_set_bit_from(i, lzo_blocks[0]->sync_bmp,
 345                               lzo_blocks[0]->sync_bmp_nbits) {
 346                 if (i > max)
 347                         continue;
 348
 349                 ret = regcache_read(map, i, &val);
 350                 if (ret)
 351                         return ret;
 352
 353                 /* Is this the hardware default?  If so skip. */
 354                 ret = regcache_lookup_reg(map, i);
 355                 if (ret > 0 && val == map->reg_defaults[ret].def)
 356                         continue;
 357
 358                 map->cache_bypass = true;
 359                 ret = _regmap_write(map, i, val);
 360                 map->cache_bypass = false;
 361                 if (ret)
 362                         return ret;
 363                 dev_dbg(map->dev, "Synced register %#x, value %#x\n",
 364                         i, val);
 365         }
 366
 367         return 0;
 368 }
 369
 370 struct regcache_ops regcache_lzo_ops = {
 371         .type = REGCACHE_COMPRESSED,
 372         .name = "lzo",
 373         .init = regcache_lzo_init,
 374         .exit = regcache_lzo_exit,
 375         .read = regcache_lzo_read,
 376         .write = regcache_lzo_write,
 377         .sync = regcache_lzo_sync
 378 };