[U-Boot] [PATCH 2/5] drivers: dma: Add function to zeroes a range of destination such as memory

[Simon Glass]

Hi Tien,

On 31 May 2018 at 02:08,  <tien.fong.chee at intel.com> wrote:
> From: Tien Fong Chee <tien.fong.chee at intel.com>
>
> This new DMA class function enables DMA being used for initializing
> a range of destination such as memory to zeros. This is quite useful to
> help accelerating the performance in scrubbing memory when ECC is enabled.
>
> Signed-off-by: Tien Fong Chee <tien.fong.chee at intel.com>
> ---
>  drivers/dma/dma-uclass.c | 15 +++++++++++++++
>  include/dma.h            | 12 ++++++++++++
>  2 files changed, 27 insertions(+)
>
> diff --git a/drivers/dma/dma-uclass.c b/drivers/dma/dma-uclass.c
> index a33f7d5..cb83c24 100644
> --- a/drivers/dma/dma-uclass.c
> +++ b/drivers/dma/dma-uclass.c
> @@ -61,6 +61,21 @@ int dma_memcpy(void *dst, void *src, size_t len)
>         return ops->transfer(dev, DMA_MEM_TO_MEM, dst, src, len);
>  }
>
> +int dma_memcpy_zeroes(struct udevice *dev, void *dst, size_t len)
> +{
> +       const struct dma_ops *ops;
> +
> +       ops = device_get_ops(dev);
> +       if (!ops->transfer_zeroes)
> +               return -ENOSYS;
> +
> +       /* Invalidate the area, so no writeback into the RAM races with DMA */
> +       invalidate_dcache_range((unsigned long)dst, (unsigned long)dst +
> +                               roundup(len, ARCH_DMA_MINALIGN));
> +
> +       return ops->transfer_zeroes(dev, dst, len);
> +}
> +
>  UCLASS_DRIVER(dma) = {
>         .id             = UCLASS_DMA,
>         .name           = "dma",
> diff --git a/include/dma.h b/include/dma.h
> index 50e9652..6bad2264 100644
> --- a/include/dma.h
> +++ b/include/dma.h
> @@ -46,6 +46,7 @@ struct dma_ops {
>          */
>         int (*transfer)(struct udevice *dev, int direction, void *dst,
>                         void *src, size_t len);
> +       int (*transfer_zeroes)(struct udevice *dev, void *dst, size_t len);

I wonder if this could be done by using transfer() with a src of NULL ?

>  };
>
>  /*
> @@ -82,4 +83,15 @@ int dma_get_device(u32 transfer_type, struct udevice **devp);
>   */
>  int dma_memcpy(void *dst, void *src, size_t len);
>
> +/*
> + * dma_memcpy_zeroes - Fill up destination with zeros through DMA.
> + *
> + * @dev: The DMA device
> + * @dst: destination pointer
> + * @len: length to be copied with zero
> + * @return: on successful transfer returns zero.
> + *         on failure returns error code.
> + */
> +int dma_memcpy_zeroes(struct udevice *dev, void *dst, size_t len);
> +
>  #endif /* _DMA_H_ */
> --
> 2.2.0
>


Regards,
Simon