linux-imx

// SPDX-License-Identifier: GPL-2.0-only

#include <linux/module.h>

#include <linux/scatterlist.h>

#include <linux/mempool.h>

#include <linux/slab.h>

​

#define SG_MEMPOOL_NR       ARRAY_SIZE(sg_pools)

#define SG_MEMPOOL_SIZE     2

​

struct sg_pool {

    size_t      size;

    char        *name;

    struct kmem_cache   *slab;

    mempool_t   *pool;

};

​

#define SP(x) { .size = x, "sgpool-" __stringify(x) }

#if (SG_CHUNK_SIZE < 32)

#error SG_CHUNK_SIZE is too small (must be 32 or greater)

#endif

static struct sg_pool sg_pools[] = {

    SP(8),

    SP(16),

#if (SG_CHUNK_SIZE > 32)

    SP(32),

#if (SG_CHUNK_SIZE > 64)

    SP(64),

#if (SG_CHUNK_SIZE > 128)

    SP(128),

#if (SG_CHUNK_SIZE > 256)

#error SG_CHUNK_SIZE is too large (256 MAX)

#endif

#endif

#endif

#endif

    SP(SG_CHUNK_SIZE)

};

#undef SP

​

static inline unsigned int sg_pool_index(unsigned short nents)

{

    unsigned int index;

​

    BUG_ON(nents > SG_CHUNK_SIZE);

​

    if (nents <= 8)

        index = 0;

    else

        index = get_count_order(nents) - 3;

​

    return index;

}

​

static void sg_pool_free(struct scatterlist *sgl, unsigned int nents)

{

    struct sg_pool *sgp;

​

    sgp = sg_pools + sg_pool_index(nents);

    mempool_free(sgl, sgp->pool);

}

​

static struct scatterlist *sg_pool_alloc(unsigned int nents, gfp_t gfp_mask)

{

    struct sg_pool *sgp;

​

    sgp = sg_pools + sg_pool_index(nents);

    return mempool_alloc(sgp->pool, gfp_mask);

}

​

/**

 * sg_free_table_chained - Free a previously mapped sg table

 * @table:  The sg table header to use

 * @first_chunk: was first_chunk not NULL in sg_alloc_table_chained?

 *

 *  Description:

 *    Free an sg table previously allocated and setup with

 *    sg_alloc_table_chained().

 *

 **/

void sg_free_table_chained(struct sg_table *table, bool first_chunk)

{

    if (first_chunk && table->orig_nents <= SG_CHUNK_SIZE)

        return;

    __sg_free_table(table, SG_CHUNK_SIZE, first_chunk, sg_pool_free);

}

EXPORT_SYMBOL_GPL(sg_free_table_chained);

​

/**

 * sg_alloc_table_chained - Allocate and chain SGLs in an sg table

 * @table:  The sg table header to use

 * @nents:  Number of entries in sg list

 * @first_chunk: first SGL