Re: [PATCH v2 4/4] ArmPkg/ArmDmaLib: add support for fixed host-to-device DMA offset

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

On Sat, Nov 12, 2016 at 02:02:28PM +0100, 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>

Much more Leif-friendly, thanks.
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>

> ---
>  ArmPkg/ArmPkg.dec                      |  8 ++++++++
>  ArmPkg/Library/ArmDmaLib/ArmDmaLib.c   | 20 ++++++++++++++++++--
>  ArmPkg/Library/ArmDmaLib/ArmDmaLib.inf |  1 +
>  3 files changed, 27 insertions(+), 2 deletions(-)
> 
> diff --git a/ArmPkg/ArmPkg.dec b/ArmPkg/ArmPkg.dec
> index 3cdb5da3d4f3..090ed9951366 100644
> --- a/ArmPkg/ArmPkg.dec
> +++ b/ArmPkg/ArmPkg.dec
> @@ -134,6 +134,14 @@ [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. This
> +  # means we can rely on truncation on overflow to specify negative
> +  # offsets.
> +  #
> +  gArmTokenSpaceGuid.PcdArmDmaDeviceOffset|0x0|UINT64|0x0000044
> +
>  [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 7321388de63e..1de4a6e5b04f 100644
> --- a/ArmPkg/Library/ArmDmaLib/ArmDmaLib.c
> +++ b/ArmPkg/Library/ArmDmaLib/ArmDmaLib.c
> @@ -37,6 +37,15 @@ typedef struct {
>  
>  STATIC EFI_CPU_ARCH_PROTOCOL      *mCpu;
>  
> +STATIC
> +PHYSICAL_ADDRESS
> +HostToDeviceAddress (
> +  IN  PHYSICAL_ADDRESS  HostAddress
> +  )
> +{
> +  return HostAddress + PcdGet64 (PcdArmDmaDeviceOffset);
> +}
> +
>  /**
>    Provides the DMA controller-specific addresses needed to access system memory.
>  
> @@ -80,7 +89,14 @@ DmaMap (
>      return EFI_INVALID_PARAMETER;
>    }
>  
> -  *DeviceAddress = ConvertToPhysicalAddress (HostAddress);
> +  //
> +  // The debug implementation of UncachedMemoryAllocationLib in ArmPkg returns
> +  // a virtual uncached alias, and unmaps the cached ID mapping of the buffer,
> +  // in order to catch inadvertent references to the cached mapping.
> +  // Since HostToDeviceAddress () expects ID mapped input addresses, convert
> +  // the host address to an ID mapped address first.
> +  //
> +  *DeviceAddress = HostToDeviceAddress (ConvertToPhysicalAddress (HostAddress));
>  
>    // Remember range so we can flush on the other side
>    Map = AllocatePool (sizeof (MAP_INFO_INSTANCE));
> @@ -127,7 +143,7 @@ DmaMap (
>          CopyMem (Buffer, HostAddress, *NumberOfBytes);
>        }
>  
> -      *DeviceAddress = ConvertToPhysicalAddress ((UINTN)Buffer);
> +      *DeviceAddress = HostToDeviceAddress (ConvertToPhysicalAddress ((UINTN)Buffer));
>        Map->BufferAddress = Buffer;
>      } else {
>        Map->DoubleBuffer  = FALSE;
> diff --git a/ArmPkg/Library/ArmDmaLib/ArmDmaLib.inf b/ArmPkg/Library/ArmDmaLib/ArmDmaLib.inf
> index 31de3cfd828c..9b7dad114b18 100644
> --- a/ArmPkg/Library/ArmDmaLib/ArmDmaLib.inf
> +++ b/ArmPkg/Library/ArmDmaLib/ArmDmaLib.inf
> @@ -44,6 +44,7 @@ [Protocols]
>  [Guids]
>  
>  [Pcd]
> +  gArmTokenSpaceGuid.PcdArmDmaDeviceOffset
>  
>  [Depex]
>    gEfiCpuArchProtocolGuid
> -- 
> 2.7.4
>