regcache-lzo.c

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/*
 * Register cache access API - LZO caching support
 *
 * Copyright 2011 Wolfson Microelectronics plc
 *
 * Author: Dimitris Papastamos <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/slab.h>
#include <linux/device.h>
#include <linux/lzo.h>

#include "internal.h"

static int regcache_lzo_exit(struct regmap *map);

struct regcache_lzo_ctx {
    void *wmem;
    void *dst;
    const void *src;
    size_t src_len;
    size_t dst_len;
    size_t decompressed_size;
    unsigned long *sync_bmp;
    int sync_bmp_nbits;
};

#define LZO_BLOCK_NUM 8
static int regcache_lzo_block_count(struct regmap *map)
{
    return LZO_BLOCK_NUM;
}

static int regcache_lzo_prepare(struct regcache_lzo_ctx *lzo_ctx)
{
    lzo_ctx->wmem = kmalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
    if (!lzo_ctx->wmem)
        return -ENOMEM;
    return 0;
}

static int regcache_lzo_compress(struct regcache_lzo_ctx *lzo_ctx)
{
    size_t compress_size;
    int ret;

    ret = lzo1x_1_compress(lzo_ctx->src, lzo_ctx->src_len,
                   lzo_ctx->dst, &compress_size, lzo_ctx->wmem);
    if (ret != LZO_E_OK || compress_size > lzo_ctx->dst_len)
        return -EINVAL;
    lzo_ctx->dst_len = compress_size;
    return 0;
}

static int regcache_lzo_decompress(struct regcache_lzo_ctx *lzo_ctx)
{
    size_t dst_len;
    int ret;

    dst_len = lzo_ctx->dst_len;
    ret = lzo1x_decompress_safe(lzo_ctx->src, lzo_ctx->src_len,
                    lzo_ctx->dst, &dst_len);
    if (ret != LZO_E_OK || dst_len != lzo_ctx->dst_len)
        return -EINVAL;
    return 0;
}

static int regcache_lzo_compress_cache_block(struct regmap *map,
        struct regcache_lzo_ctx *lzo_ctx)
{
    int ret;

    lzo_ctx->dst_len = lzo1x_worst_compress(PAGE_SIZE);
    lzo_ctx->dst = kmalloc(lzo_ctx->dst_len, GFP_KERNEL);
    if (!lzo_ctx->dst) {
        lzo_ctx->dst_len = 0;
        return -ENOMEM;
    }

    ret = regcache_lzo_compress(lzo_ctx);
    if (ret < 0)
        return ret;
    return 0;
}

static int regcache_lzo_decompress_cache_block(struct regmap *map,
        struct regcache_lzo_ctx *lzo_ctx)
{
    int ret;

    lzo_ctx->dst_len = lzo_ctx->decompressed_size;
    lzo_ctx->dst = kmalloc(lzo_ctx->dst_len, GFP_KERNEL);
    if (!lzo_ctx->dst) {
        lzo_ctx->dst_len = 0;
        return -ENOMEM;
    }

    ret = regcache_lzo_decompress(lzo_ctx);
    if (ret < 0)
        return ret;
    return 0;
}

static inline int regcache_lzo_get_blkindex(struct regmap *map,
                        unsigned int reg)
{
    return ((reg / map->reg_stride) * map->cache_word_size) /
        DIV_ROUND_UP(map->cache_size_raw,
                 regcache_lzo_block_count(map));
}

static inline int regcache_lzo_get_blkpos(struct regmap *map,
                      unsigned int reg)
{
    return (reg / map->reg_stride) %
            (DIV_ROUND_UP(map->cache_size_raw,
                  regcache_lzo_block_count(map)) /
             map->cache_word_size);
}

static inline int regcache_lzo_get_blksize(struct regmap *map)
{
    return DIV_ROUND_UP(map->cache_size_raw,
                regcache_lzo_block_count(map));
}

static int regcache_lzo_init(struct regmap *map)
{
    struct regcache_lzo_ctx **lzo_blocks;
    size_t bmp_size;
    int ret, i, blksize, blkcount;
    const char *p, *end;
    unsigned long *sync_bmp;

    ret = 0;

    blkcount = regcache_lzo_block_count(map);
    map->cache = kzalloc(blkcount * sizeof *lzo_blocks,
                 GFP_KERNEL);
    if (!map->cache)
        return -ENOMEM;
    lzo_blocks = map->cache;

    /*
     * allocate a bitmap to be used when syncing the cache with
     * the hardware.  Each time a register is modified, the corresponding
     * bit is set in the bitmap, so we know that we have to sync
     * that register.
     */
    bmp_size = map->num_reg_defaults_raw;
    sync_bmp = kmalloc(BITS_TO_LONGS(bmp_size) * sizeof(long),
               GFP_KERNEL);
    if (!sync_bmp) {
        ret = -ENOMEM;
        goto err;
    }
    bitmap_zero(sync_bmp, bmp_size);

    /* allocate the lzo blocks and initialize them */
    for (i = 0; i < blkcount; i++) {
        lzo_blocks[i] = kzalloc(sizeof **lzo_blocks,
                    GFP_KERNEL);
        if (!lzo_blocks[i]) {
            kfree(sync_bmp);
            ret = -ENOMEM;
            goto err;
        }
        lzo_blocks[i]->sync_bmp = sync_bmp;
        lzo_blocks[i]->sync_bmp_nbits = bmp_size;
        /* alloc the working space for the compressed block */
        ret = regcache_lzo_prepare(lzo_blocks[i]);
        if (ret < 0)
            goto err;
    }

    blksize = regcache_lzo_get_blksize(map);
    p = map->reg_defaults_raw;
    end = map->reg_defaults_raw + map->cache_size_raw;
    /* compress the register map and fill the lzo blocks */
    for (i = 0; i < blkcount; i++, p += blksize) {
        lzo_blocks[i]->src = p;
        if (p + blksize > end)
            lzo_blocks[i]->src_len = end - p;
        else
            lzo_blocks[i]->src_len = blksize;
        ret = regcache_lzo_compress_cache_block(map,
                               lzo_blocks[i]);
        if (ret < 0)
            goto err;
        lzo_blocks[i]->decompressed_size =
            lzo_blocks[i]->src_len;
    }

    return 0;
err:
    regcache_lzo_exit(map);
    return ret;
}

static int regcache_lzo_exit(struct regmap *map)
{
    struct regcache_lzo_ctx **lzo_blocks;
    int i, blkcount;

    lzo_blocks = map->cache;
    if (!lzo_blocks)
        return 0;

    blkcount = regcache_lzo_block_count(map);
    /*
     * the pointer to the bitmap used for syncing the cache
     * is shared amongst all lzo_blocks.  Ensure it is freed
     * only once.
     */
    if (lzo_blocks[0])
        kfree(lzo_blocks[0]->sync_bmp);
    for (i = 0; i < blkcount; i++) {
        if (lzo_blocks[i]) {
            kfree(lzo_blocks[i]->wmem);
            kfree(lzo_blocks[i]->dst);
        }
        /* each lzo_block is a pointer returned by kmalloc or NULL */
        kfree(lzo_blocks[i]);
    }
    kfree(lzo_blocks);
    map->cache = NULL;
    return 0;
}

static int regcache_lzo_read(struct regmap *map,
                 unsigned int reg, unsigned int *value)
{
    struct regcache_lzo_ctx *lzo_block, **lzo_blocks;
    int ret, blkindex, blkpos;
    size_t blksize, tmp_dst_len;
    void *tmp_dst;

    /* index of the compressed lzo block */
    blkindex = regcache_lzo_get_blkindex(map, reg);
    /* register index within the decompressed block */
    blkpos = regcache_lzo_get_blkpos(map, reg);
    /* size of the compressed block */
    blksize = regcache_lzo_get_blksize(map);
    lzo_blocks = map->cache;
    lzo_block = lzo_blocks[blkindex];

    /* save the pointer and length of the compressed block */
    tmp_dst = lzo_block->dst;
    tmp_dst_len = lzo_block->dst_len;

    /* prepare the source to be the compressed block */
    lzo_block->src = lzo_block->dst;
    lzo_block->src_len = lzo_block->dst_len;

    /* decompress the block */
    ret = regcache_lzo_decompress_cache_block(map, lzo_block);
    if (ret >= 0)
        /* fetch the value from the cache */
        *value = regcache_get_val(lzo_block->dst, blkpos,
                      map->cache_word_size);

    kfree(lzo_block->dst);
    /* restore the pointer and length of the compressed block */
    lzo_block->dst = tmp_dst;
    lzo_block->dst_len = tmp_dst_len;

    return ret;
}

static int regcache_lzo_write(struct regmap *map,
                  unsigned int reg, unsigned int value)
{
    struct regcache_lzo_ctx *lzo_block, **lzo_blocks;
    int ret, blkindex, blkpos;
    size_t blksize, tmp_dst_len;
    void *tmp_dst;

    /* index of the compressed lzo block */
    blkindex = regcache_lzo_get_blkindex(map, reg);
    /* register index within the decompressed block */
    blkpos = regcache_lzo_get_blkpos(map, reg);
    /* size of the compressed block */
    blksize = regcache_lzo_get_blksize(map);
    lzo_blocks = map->cache;
    lzo_block = lzo_blocks[blkindex];

    /* save the pointer and length of the compressed block */
    tmp_dst = lzo_block->dst;
    tmp_dst_len = lzo_block->dst_len;

    /* prepare the source to be the compressed block */
    lzo_block->src = lzo_block->dst;
    lzo_block->src_len = lzo_block->dst_len;

    /* decompress the block */
    ret = regcache_lzo_decompress_cache_block(map, lzo_block);
    if (ret < 0) {
        kfree(lzo_block->dst);
        goto out;
    }

    /* write the new value to the cache */
    if (regcache_set_val(lzo_block->dst, blkpos, value,
                 map->cache_word_size)) {
        kfree(lzo_block->dst);
        goto out;
    }

    /* prepare the source to be the decompressed block */
    lzo_block->src = lzo_block->dst;
    lzo_block->src_len = lzo_block->dst_len;

    /* compress the block */
    ret = regcache_lzo_compress_cache_block(map, lzo_block);
    if (ret < 0) {
        kfree(lzo_block->dst);
        kfree(lzo_block->src);
        goto out;
    }

    /* set the bit so we know we have to sync this register */
    set_bit(reg / map->reg_stride, lzo_block->sync_bmp);
    kfree(tmp_dst);
    kfree(lzo_block->src);
    return 0;
out:
    lzo_block->dst = tmp_dst;
    lzo_block->dst_len = tmp_dst_len;
    return ret;
}

static int regcache_lzo_sync(struct regmap *map, unsigned int min,
                 unsigned int max)
{
    struct regcache_lzo_ctx **lzo_blocks;
    unsigned int val;
    int i;
    int ret;

    lzo_blocks = map->cache;
    i = min;
    for_each_set_bit_from(i, lzo_blocks[0]->sync_bmp,
                  lzo_blocks[0]->sync_bmp_nbits) {
        if (i > max)
            continue;

        ret = regcache_read(map, i, &val);
        if (ret)
            return ret;

        /* Is this the hardware default?  If so skip. */
        ret = regcache_lookup_reg(map, i);
        if (ret > 0 && val == map->reg_defaults[ret].def)
            continue;

        map->cache_bypass = 1;
        ret = _regmap_write(map, i, val);
        map->cache_bypass = 0;
        if (ret)
            return ret;
        dev_dbg(map->dev, "Synced register %#x, value %#x\n",
            i, val);
    }

    return 0;
}

struct regcache_ops regcache_lzo_ops = {
    .type = REGCACHE_COMPRESSED,
    .name = "lzo",
    .init = regcache_lzo_init,
    .exit = regcache_lzo_exit,
    .read = regcache_lzo_read,
    .write = regcache_lzo_write,
    .sync = regcache_lzo_sync
};