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