/*
 * Register cache access API - LZO caching support
 *
 * Copyright 2011 Wolfson Microelectronics plc
 *
 * Author: Dimitris Papastamos <dp@opensource.wolfsonmicro.com>
 *
 * 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/device.h>
#include <linux/lzo.h>
#include <linux/slab.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 = kcalloc(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_array(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 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);
        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(map, lzo_block->dst, blkpos);

        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 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);
        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(map, lzo_block->dst, blkpos, value)) {
                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 = true;
                ret = _regmap_write(map, i, val);
                map->cache_bypass = false;
                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
};