Re: [PATCH] ArmPkg/ArmDmaLib: add support for fixed host-to-device DMA offset

[Leif Lindholm <leif.lindholm@linaro.org>]

On Tue, Nov 08, 2016 at 01:04:55PM +0000, Ard Biesheuvel wrote:
> Some devices, such as the Raspberry Pi3, have a fixed offset between memory
> addresses as seen by the host and as seen by the other bus masters. So add
> a new PCD that allows this fixed offset to be recorded, and to be used when
> returning device addresses from the DmaLib mapping routines.
>
> Contributed-under: TianoCore Contribution Agreement 1.0
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> ---
>  ArmPkg/ArmPkg.dec                      |  6 ++++++
>  ArmPkg/Library/ArmDmaLib/ArmDmaLib.c   | 13 +++++++++++--
>  ArmPkg/Library/ArmDmaLib/ArmDmaLib.inf |  1 +
>  3 files changed, 18 insertions(+), 2 deletions(-)
> 
> diff --git a/ArmPkg/ArmPkg.dec b/ArmPkg/ArmPkg.dec
> index 3cdb5da3d4f3..b2d59a168337 100644
> --- a/ArmPkg/ArmPkg.dec
> +++ b/ArmPkg/ArmPkg.dec
> @@ -134,6 +134,12 @@ [PcdsFixedAtBuild.common]
>    gArmTokenSpaceGuid.PcdFdSize|0|UINT32|0x0000002C
>    gArmTokenSpaceGuid.PcdFvSize|0|UINT32|0x0000002E
>  
> +  #
> +  # Value to add to a host address to obtain a device address
> +  # (using unsigned 64-bit integer arithmetic on both ARM and AArch64)
> +  #
> +  gArmTokenSpaceGuid.PcdArmDmaDeviceOffset|0x0|UINT64|0x0000044
> +

Is the offset always positive?

>  [PcdsFixedAtBuild.common, PcdsPatchableInModule.common]
>    gArmTokenSpaceGuid.PcdFdBaseAddress|0|UINT64|0x0000002B
>    gArmTokenSpaceGuid.PcdFvBaseAddress|0|UINT64|0x0000002D
> diff --git a/ArmPkg/Library/ArmDmaLib/ArmDmaLib.c b/ArmPkg/Library/ArmDmaLib/ArmDmaLib.c
> index d48d6ff6dbbb..d6dee78a254d 100644
> --- a/ArmPkg/Library/ArmDmaLib/ArmDmaLib.c
> +++ b/ArmPkg/Library/ArmDmaLib/ArmDmaLib.c
> @@ -39,6 +39,15 @@ typedef struct {
>  EFI_CPU_ARCH_PROTOCOL      *gCpu;
>  UINTN                      gCacheAlignment = 0;
>  
> +STATIC
> +PHYSICAL_ADDRESS
> +HostToDeviceAddress (
> +  IN  PHYSICAL_ADDRESS  HostAddress
> +  )
> +{
> +  return HostAddress + PcdGet64 (PcdArmDmaDeviceOffset);
> +}
> +
>  /**
>    Provides the DMA controller-specific addresses needed to access system memory.
>  
> @@ -82,7 +91,7 @@ DmaMap (
>      return EFI_INVALID_PARAMETER;
>    }
>  
> -  *DeviceAddress = ConvertToPhysicalAddress (HostAddress);
> +  *DeviceAddress = HostToDeviceAddress (ConvertToPhysicalAddress (HostAddress));
>  
>    // Remember range so we can flush on the other side
>    Map = AllocatePool (sizeof (MAP_INFO_INSTANCE));
> @@ -129,7 +138,7 @@ DmaMap (
>          CopyMem (Buffer, HostAddress, *NumberOfBytes);
>        }
>  
> -      *DeviceAddress = (PHYSICAL_ADDRESS)(UINTN)Buffer;
> +      *DeviceAddress = HostToDeviceAddress ((PHYSICAL_ADDRESS)(UINTN)Buffer);
>      } else {
>        Map->DoubleBuffer  = FALSE;
>      }
> diff --git a/ArmPkg/Library/ArmDmaLib/ArmDmaLib.inf b/ArmPkg/Library/ArmDmaLib/ArmDmaLib.inf
> index 95c13006eaac..36c23f486974 100644
> --- a/ArmPkg/Library/ArmDmaLib/ArmDmaLib.inf
> +++ b/ArmPkg/Library/ArmDmaLib/ArmDmaLib.inf
> @@ -46,6 +46,7 @@ [Protocols]
>  [Guids]
>  
>  [Pcd]
> +  gArmTokenSpaceGuid.PcdArmDmaDeviceOffset
>  
>  [Depex]
>    gEfiCpuArchProtocolGuid
> -- 
> 2.7.4
>