[PATCH 1/7] iommu: Add DMA mapping operations

[Simon Glass]

Hi Mark,

On Tue, 17 Jan 2023 at 15:04, Mark Kettenis <kettenis at openbsd.org> wrote:
>
> In order to support IOMMUs in non-bypass mode we need device ops
> to map and unmap DMA memory.  The map operation enters a mapping
> for a region specified by CPU address and size into the translation
> table of the IOMMU and returns a DMA address suitable for
> programming the device to do DMA.  The unmap operation removes
> this mapping from the translation table of the IOMMU.
>
> Signed-off-by: Mark Kettenis <kettenis at openbsd.org>
> ---
>  drivers/iommu/iommu-uclass.c | 28 ++++++++++++++++++++++++++++
>  include/dm/device.h          |  3 +++
>  include/iommu.h              | 24 ++++++++++++++++++++++++
>  3 files changed, 55 insertions(+)
>
> diff --git a/drivers/iommu/iommu-uclass.c b/drivers/iommu/iommu-uclass.c
> index ed917b3c3e..f6b1457736 100644
> --- a/drivers/iommu/iommu-uclass.c
> +++ b/drivers/iommu/iommu-uclass.c
> @@ -7,6 +7,9 @@
>
>  #include <common.h>
>  #include <dm.h>
> +#include <iommu.h>
> +#include <phys2bus.h>
> +#include <asm/io.h>
>
>  #if (CONFIG_IS_ENABLED(OF_CONTROL) && !CONFIG_IS_ENABLED(OF_PLATDATA))
>  int dev_iommu_enable(struct udevice *dev)
> @@ -33,12 +36,37 @@ int dev_iommu_enable(struct udevice *dev)
>                               __func__, ret);
>                         return ret;
>                 }
> +               dev->iommu = dev_iommu;
>         }
>
>         return 0;
>  }
>  #endif
>
> +dma_addr_t dev_iommu_dma_map(struct udevice *dev, void *addr, size_t size)
> +{
> +       const struct iommu_ops *ops;
> +
> +       if (dev->iommu) {
> +               ops = device_get_ops(dev->iommu);
> +               if (ops && ops->map)
> +                       return ops->map(dev->iommu, addr, size);
> +       }
> +
> +       return dev_phys_to_bus(dev, virt_to_phys(addr));
> +}
> +
> +void dev_iommu_dma_unmap(struct udevice *dev, dma_addr_t addr, size_t size)
> +{
> +       const struct iommu_ops *ops;
> +
> +       if (dev->iommu) {
> +               ops = device_get_ops(dev->iommu);
> +               if (ops && ops->unmap)
> +                       ops->unmap(dev->iommu, addr, size);
> +       }
> +}
> +
>  UCLASS_DRIVER(iommu) = {
>         .id             = UCLASS_IOMMU,
>         .name           = "iommu",
> diff --git a/include/dm/device.h b/include/dm/device.h
> index f3f953c9af..abe1927ecd 100644
> --- a/include/dm/device.h
> +++ b/include/dm/device.h
> @@ -194,6 +194,9 @@ struct udevice {
>  #if CONFIG_IS_ENABLED(DM_DMA)
>         ulong dma_offset;
>  #endif
> +#if CONFIG_IS_ENABLED(IOMMU)
> +       struct udevice *iommu;
> +#endif
>  };
>
>  static inline int dm_udevice_size(void)
> diff --git a/include/iommu.h b/include/iommu.h
> index 6c46adf449..cf9719c5e9 100644
> --- a/include/iommu.h
> +++ b/include/iommu.h
> @@ -3,6 +3,27 @@
>
>  struct udevice;
>
> +struct iommu_ops {
> +       /**
> +        * map() - map DMA memory
> +        *
> +        * @dev:        device for which to map DMA memory
> +        * @addr:       CPU address of the memory
> +        * @size:       size of the memory
> +        * @return DMA address for the device
> +        */
> +       dma_addr_t (*map)(struct udevice *dev, void *addr, size_t size);
> +
> +       /**
> +        * unmap() - unmap DMA memory
> +        *
> +        * @dev:        device for which to unmap DMA memory
> +        * @addr:       DMA address of the memory
> +        * @size:       size of the memory
> +        */
> +       void (*unmap)(struct udevice *dev, dma_addr_t addr, size_t size);
> +};
> +
>  #if (CONFIG_IS_ENABLED(OF_CONTROL) && !CONFIG_IS_ENABLED(OF_PLATDATA)) && \
>         CONFIG_IS_ENABLED(IOMMU)
>  int dev_iommu_enable(struct udevice *dev);
> @@ -13,4 +34,7 @@ static inline int dev_iommu_enable(struct udevice *dev)
>  }
>  #endif
>
> +dma_addr_t dev_iommu_dma_map(struct udevice *dev, void *addr, size_t size);
> +void dev_iommu_dma_unmap(struct udevice *dev, dma_addr_t addr, size_t size);
> +
>  #endif

Please add some tests for these operations to test/dm/iommc.c

Regards,
Simon