Re: [PATCHv9 3/6] dma-mapping: add dma_{map,unmap}_resource

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Niklas,

Thank you for the patch.

On Wednesday 10 Aug 2016 13:22:16 Niklas Söderlund wrote:
> Map/Unmap a device MMIO resource from a physical address. If no dma_map_ops
> method is available the operation is a no-op.
> 
> Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>

Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

> ---
>  Documentation/DMA-API.txt   | 22 +++++++++++++++++-----
>  include/linux/dma-mapping.h | 36 ++++++++++++++++++++++++++++++++++++
>  2 files changed, 53 insertions(+), 5 deletions(-)
> 
> diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt
> index 1d26eeb6..6b20128 100644
> --- a/Documentation/DMA-API.txt
> +++ b/Documentation/DMA-API.txt
> @@ -277,14 +277,26 @@ and <size> parameters are provided to do partial page
> mapping, it is recommended that you never use these unless you really know
> what the cache width is.
> 
> +dma_addr_t
> +dma_map_resource(struct device *dev, phys_addr_t phys_addr, size_t size,
> +		 enum dma_data_direction dir, unsigned long attrs)
> +
> +void
> +dma_unmap_resource(struct device *dev, dma_addr_t addr, size_t size,
> +		   enum dma_data_direction dir, unsigned long attrs)
> +
> +API for mapping and unmapping for MMIO resources. All the notes and
> +warnings for the other mapping APIs apply here. The API should only be
> +used to map device MMIO resources, mapping of RAM is not permitted.
> +
>  int
>  dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
> 
> -In some circumstances dma_map_single() and dma_map_page() will fail to
> create -a mapping. A driver can check for these errors by testing the
> returned -DMA address with dma_mapping_error(). A non-zero return value
> means the mapping -could not be created and the driver should take
> appropriate action (e.g. -reduce current DMA mapping usage or delay and try
> again later).
> +In some circumstances dma_map_single(), dma_map_page() and
> dma_map_resource() +will fail to create a mapping. A driver can check for
> these errors by testing +the returned DMA address with dma_mapping_error().
> A non-zero return value +means the mapping could not be created and the
> driver should take appropriate +action (e.g. reduce current DMA mapping
> usage or delay and try again later).
> 
>  	int
>  	dma_map_sg(struct device *dev, struct scatterlist *sg,
> diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
> index e3bd27f..9a07882 100644
> --- a/include/linux/dma-mapping.h
> +++ b/include/linux/dma-mapping.h
> @@ -264,6 +264,42 @@ static inline void dma_unmap_page(struct device *dev,
> dma_addr_t addr, debug_dma_unmap_page(dev, addr, size, dir, false);
>  }
> 
> +static inline dma_addr_t dma_map_resource(struct device *dev,
> +					  phys_addr_t phys_addr,
> +					  size_t size,
> +					  enum dma_data_direction dir,
> +					  unsigned long attrs)
> +{
> +	struct dma_map_ops *ops = get_dma_ops(dev);
> +	unsigned long pfn = __phys_to_pfn(phys_addr);
> +	dma_addr_t addr;
> +
> +	BUG_ON(!valid_dma_direction(dir));
> +
> +	/* Don't allow RAM to be mapped */
> +	BUG_ON(pfn_valid(pfn));
> +
> +	addr = phys_addr;
> +	if (ops->map_resource)
> +		addr = ops->map_resource(dev, phys_addr, size, dir, attrs);
> +
> +	debug_dma_map_resource(dev, phys_addr, size, dir, addr);
> +
> +	return addr;
> +}
> +
> +static inline void dma_unmap_resource(struct device *dev, dma_addr_t addr,
> +				      size_t size, enum dma_data_direction 
dir,
> +				      unsigned long attrs)
> +{
> +	struct dma_map_ops *ops = get_dma_ops(dev);
> +
> +	BUG_ON(!valid_dma_direction(dir));
> +	if (ops->unmap_resource)
> +		ops->unmap_resource(dev, addr, size, dir, attrs);
> +	debug_dma_unmap_resource(dev, addr, size, dir);
> +}
> +
>  static inline void dma_sync_single_for_cpu(struct device *dev, dma_addr_t
> addr, size_t size,
>  					   enum dma_data_direction dir)

-- 
Regards,

Laurent Pinchart