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    Subject[PATCH][RESEND 1/8] lib/genalloc: add a helper function for DMA buffer allocation
    Date
    When using pool space for DMA buffer, there might be duplicated calling
    of gen_pool_alloc() and gen_pool_virt_to_phys() in each implementation.

    Thus it's better to add a simple helper function, a compatible one to
    the common dma_alloc_coherent(), to save some code.

    Signed-off-by: Nicolin Chen <b42378@freescale.com>
    ---
    include/linux/genalloc.h | 2 ++
    lib/genalloc.c | 28 ++++++++++++++++++++++++++++
    2 files changed, 30 insertions(+)

    diff --git a/include/linux/genalloc.h b/include/linux/genalloc.h
    index f8d41cb..1eda33d 100644
    --- a/include/linux/genalloc.h
    +++ b/include/linux/genalloc.h
    @@ -94,6 +94,8 @@ static inline int gen_pool_add(struct gen_pool *pool, unsigned long addr,
    }
    extern void gen_pool_destroy(struct gen_pool *);
    extern unsigned long gen_pool_alloc(struct gen_pool *, size_t);
    +extern void *gen_pool_dma_alloc(struct gen_pool *pool, size_t size,
    + dma_addr_t *dma);
    extern void gen_pool_free(struct gen_pool *, unsigned long, size_t);
    extern void gen_pool_for_each_chunk(struct gen_pool *,
    void (*)(struct gen_pool *, struct gen_pool_chunk *, void *), void *);
    diff --git a/lib/genalloc.c b/lib/genalloc.c
    index 26cf20b..dda3116 100644
    --- a/lib/genalloc.c
    +++ b/lib/genalloc.c
    @@ -313,6 +313,34 @@ retry:
    EXPORT_SYMBOL(gen_pool_alloc);

    /**
    + * gen_pool_dma_alloc - allocate special memory from the pool for DMA usage
    + * @pool: pool to allocate from
    + * @size: number of bytes to allocate from the pool
    + * @dma: dma-view physical address
    + *
    + * Allocate the requested number of bytes from the specified pool.
    + * Uses the pool allocation function (with first-fit algorithm by default).
    + * Can not be used in NMI handler on architectures without
    + * NMI-safe cmpxchg implementation.
    + */
    +void *gen_pool_dma_alloc(struct gen_pool *pool, size_t size, dma_addr_t *dma)
    +{
    + unsigned long vaddr;
    +
    + if (!pool)
    + return NULL;
    +
    + vaddr = gen_pool_alloc(pool, size);
    + if (!vaddr)
    + return NULL;
    +
    + *dma = gen_pool_virt_to_phys(pool, vaddr);
    +
    + return (void *)vaddr;
    +}
    +EXPORT_SYMBOL(gen_pool_dma_alloc);
    +
    +/**
    * gen_pool_free - free allocated special memory back to the pool
    * @pool: pool to free to
    * @addr: starting address of memory to free back to pool
    --
    1.8.4



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