On Tue, Feb 14, 2023 at 3:27 PM Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx> wrote:
>
> These API has been introduced:
>
> * virtio_dma_need_sync
> * virtio_dma_sync_single_range_for_cpu
> * virtio_dma_sync_single_range_for_device
What's the advantages of exporting internal logic like
virtio_dma_need_sync() over hiding it in
virtio_dma_sync_single_range_for_cpu() and
virtio_dma_sync_single_range_for_device()?
Thanks
>
> These APIs can be used together with the premapped mechanism to sync the
> DMA address.
>
> Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
> ---
> drivers/virtio/virtio_ring.c | 70 ++++++++++++++++++++++++++++++++++++
> include/linux/virtio.h | 8 +++++
> 2 files changed, 78 insertions(+)
>
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index 855338609c7f..84129b8c3e2a 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -3264,4 +3264,74 @@ void virtio_dma_unmap(struct device *dev, dma_addr_t dma, unsigned int length,
> }
> EXPORT_SYMBOL_GPL(virtio_dma_unmap);
>
> +/**
> + * virtio_dma_need_sync - check a dma address needs sync
> + * @dev: virtio device
> + * @addr: DMA address
> + *
> + * This API is only for pre-mapped buffers, for non premapped buffers virtio
> + * core handles DMA API internally.
> + */
> +bool virtio_dma_need_sync(struct device *dev, dma_addr_t addr)
> +{
> + struct virtio_device *vdev = dev_to_virtio(dev);
> +
> + if (!vring_use_dma_api(vdev))
> + return 0;
> +
> + return dma_need_sync(vdev->dev.parent, addr);
> +}
> +EXPORT_SYMBOL_GPL(virtio_dma_need_sync);
> +
> +/**
> + * virtio_dma_sync_single_range_for_cpu - dma sync for cpu
> + * @dev: virtio device
> + * @addr: DMA address
> + * @offset: DMA address offset
> + * @size: mem size for sync
> + * @dir: DMA direction
> + *
> + * Before calling this function, use virtio_dma_need_sync() to confirm that the
> + * DMA address really needs to be synchronized
> + *
> + * This API is only for pre-mapped buffers, for non premapped buffers virtio
> + * core handles DMA API internally.
> + */
> +void virtio_dma_sync_single_range_for_cpu(struct device *dev, dma_addr_t addr,
> + unsigned long offset, size_t size,
> + enum dma_data_direction dir)
> +{
> + struct virtio_device *vdev = dev_to_virtio(dev);
> +
> + dma_sync_single_range_for_cpu(vdev->dev.parent, addr, offset,
> + size, DMA_BIDIRECTIONAL);
> +}
> +EXPORT_SYMBOL_GPL(virtio_dma_sync_single_range_for_cpu);
> +
> +/**
> + * virtio_dma_sync_single_range_for_device - dma sync for device
> + * @dev: virtio device
> + * @addr: DMA address
> + * @offset: DMA address offset
> + * @size: mem size for sync
> + * @dir: DMA direction
> + *
> + * Before calling this function, use virtio_dma_need_sync() to confirm that the
> + * DMA address really needs to be synchronized
> + *
> + * This API is only for pre-mapped buffers, for non premapped buffers virtio
> + * core handles DMA API internally.
> + */
> +void virtio_dma_sync_single_range_for_device(struct device *dev,
> + dma_addr_t addr,
> + unsigned long offset, size_t size,
> + enum dma_data_direction dir)
> +{
> + struct virtio_device *vdev = dev_to_virtio(dev);
> +
> + dma_sync_single_range_for_device(vdev->dev.parent, addr, offset,
> + size, DMA_BIDIRECTIONAL);
> +}
> +EXPORT_SYMBOL_GPL(virtio_dma_sync_single_range_for_device);
> +
> MODULE_LICENSE("GPL");
> diff --git a/include/linux/virtio.h b/include/linux/virtio.h
> index b5fa71476737..d0e707d744a0 100644
> --- a/include/linux/virtio.h
> +++ b/include/linux/virtio.h
> @@ -225,4 +225,12 @@ dma_addr_t virtio_dma_map(struct device *dev, void *addr, unsigned int length,
> int virtio_dma_mapping_error(struct device *dev, dma_addr_t addr);
> void virtio_dma_unmap(struct device *dev, dma_addr_t dma, unsigned int length,
> enum dma_data_direction dir);
> +bool virtio_dma_need_sync(struct device *dev, dma_addr_t addr);
> +void virtio_dma_sync_single_range_for_cpu(struct device *dev, dma_addr_t addr,
> + unsigned long offset, size_t size,
> + enum dma_data_direction dir);
> +void virtio_dma_sync_single_range_for_device(struct device *dev,
> + dma_addr_t addr,
> + unsigned long offset, size_t size,
> + enum dma_data_direction dir);
> #endif /* _LINUX_VIRTIO_H */
> --
> 2.32.0.3.g01195cf9f
>
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