Re: [PATCH v6 6/8] dma-mapping: detect and configure IOMMU in of_dma_configure

[Rob Clark <robdclark-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

On Mon, Dec 1, 2014 at 11:57 AM, Will Deacon <will.deacon-5wv7dgnIgG8@public.gmane.org> wrote:
> This patch extends of_dma_configure so that it sets up the IOMMU for a
> device, as well as the coherent/non-coherent DMA mapping ops.
>
> Acked-by: Arnd Bergmann <arnd-r2nGTMty4D4@public.gmane.org>
> Acked-by: Marek Szyprowski <m.szyprowski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
> Tested-by: Robin Murphy <robin.murphy-5wv7dgnIgG8@public.gmane.org>
> Signed-off-by: Will Deacon <will.deacon-5wv7dgnIgG8@public.gmane.org>
> ---
>  arch/arm/include/asm/dma-mapping.h |  4 +++-
>  drivers/of/platform.c              | 21 ++++++++++++++-------
>  include/linux/dma-mapping.h        |  8 +++++++-
>  3 files changed, 24 insertions(+), 9 deletions(-)
>
> diff --git a/arch/arm/include/asm/dma-mapping.h b/arch/arm/include/asm/dma-mapping.h
> index dc3420e77758..f3c0d953f6a2 100644
> --- a/arch/arm/include/asm/dma-mapping.h
> +++ b/arch/arm/include/asm/dma-mapping.h
> @@ -121,7 +121,9 @@ static inline unsigned long dma_max_pfn(struct device *dev)
>  }
>  #define dma_max_pfn(dev) dma_max_pfn(dev)
>
> -static inline void arch_setup_dma_ops(struct device *dev, bool coherent)
> +static inline void arch_setup_dma_ops(struct device *dev, u64 dma_base,
> +                                     u64 size, struct iommu_ops *iommu,
> +                                     bool coherent)
>  {
>         if (coherent)
>                 set_dma_ops(dev, &arm_coherent_dma_ops);
> diff --git a/drivers/of/platform.c b/drivers/of/platform.c
> index ff1f4e9afccb..b89caf8c7586 100644
> --- a/drivers/of/platform.c
> +++ b/drivers/of/platform.c
> @@ -19,6 +19,7 @@
>  #include <linux/slab.h>
>  #include <linux/of_address.h>
>  #include <linux/of_device.h>
> +#include <linux/of_iommu.h>
>  #include <linux/of_irq.h>
>  #include <linux/of_platform.h>
>  #include <linux/platform_device.h>
> @@ -166,6 +167,7 @@ static void of_dma_configure(struct device *dev)
>         int ret;
>         bool coherent;
>         unsigned long offset;
> +       struct iommu_ops *iommu;
>
>         /*
>          * Set default dma-mask to 32 bit. Drivers are expected to setup
> @@ -194,7 +196,16 @@ static void of_dma_configure(struct device *dev)
>         dev_dbg(dev, "device is%sdma coherent\n",
>                 coherent ? " " : " not ");
>
> -       arch_setup_dma_ops(dev, coherent);
> +       iommu = of_iommu_configure(dev);
> +       dev_dbg(dev, "device is%sbehind an iommu\n",
> +               iommu ? " " : " not ");
> +
> +       arch_setup_dma_ops(dev, dma_addr, size, iommu, coherent);


so, what is the way for a driver that explicitly wants to manage it's
own device virtual address space to opt out of this?  I suspect that
won't be the common case, but for a gpu, if dma layer all of a sudden
thinks it is in control of the gpu's virtual address space, things are
going to end in tears..

BR,
-R


> +}
> +
> +static void of_dma_deconfigure(struct device *dev)
> +{
> +       arch_teardown_dma_ops(dev);
>  }
>
>  /**
> @@ -223,16 +234,12 @@ static struct platform_device *of_platform_device_create_pdata(
>         if (!dev)
>                 goto err_clear_flag;
>
> -       of_dma_configure(&dev->dev);
>         dev->dev.bus = &platform_bus_type;
>         dev->dev.platform_data = platform_data;
> -
> -       /* We do not fill the DMA ops for platform devices by default.
> -        * This is currently the responsibility of the platform code
> -        * to do such, possibly using a device notifier
> -        */
> +       of_dma_configure(&dev->dev);
>
>         if (of_device_add(dev) != 0) {
> +               of_dma_deconfigure(&dev->dev);
>                 platform_device_put(dev);
>                 goto err_clear_flag;
>         }
> diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
> index 8a1560f95d4a..c3007cb4bfa6 100644
> --- a/include/linux/dma-mapping.h
> +++ b/include/linux/dma-mapping.h
> @@ -130,7 +130,13 @@ static inline int dma_coerce_mask_and_coherent(struct device *dev, u64 mask)
>  extern u64 dma_get_required_mask(struct device *dev);
>
>  #ifndef arch_setup_dma_ops
> -static inline void arch_setup_dma_ops(struct device *dev, bool coherent) { }
> +static inline void arch_setup_dma_ops(struct device *dev, u64 dma_base,
> +                                     u64 size, struct iommu_ops *iommu,
> +                                     bool coherent) { }
> +#endif
> +
> +#ifndef arch_teardown_dma_ops
> +static inline void arch_teardown_dma_ops(struct device *dev) { }
>  #endif
>
>  static inline unsigned int dma_get_max_seg_size(struct device *dev)
> --
> 2.1.1
>
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