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ArmVirtPkg/QemuFwCfgLib: use DMA for QemuFwCfgWriteBytes() if available 

We use the "InternalQemuFwCfgReadBytes" static function pointer to
dispatch the reading of fw_cfg bytes between MMIO and DMA. This pointer is
initialized to MMIO, and we set it to DMA in the library constructor if
DMA is available.

Unlike the above, we write fw_cfg bytes only with MMIO at the moment.
Extend the write functionality so that it follows the read pattern:
- introduce the new function typedef WRITE_BYTES_FUNCTION,
- extract the current (MMIO-only) write internals from
  QemuFwCfgWriteBytes() to MmioWriteBytes(),
- provide a DMA-based implementation in DmaWriteBytes() -- a thin wrapper
  around DmaTransferBytes(),
- set the new static function pointer "InternalQemuFwCfgWriteBytes"
  according to the DMA feature provided by QEMU,
- In QemuFwCfgWriteBytes(), call the best available method through
  "InternalQemuFwCfgWriteBytes".

Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=359
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
This commit is contained in:
Laszlo Ersek 2017-01-27 07:29:12 +01:00
parent 4175356fb4
commit e8ae381f60
1 changed files with 54 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

60
ArmVirtPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c
View File

@ -42,16 +42,32 @@ VOID (EFIAPI READ_BYTES_FUNCTION) (
IN VOID *Buffer OPTIONAL
);
/**
Writes bytes from a buffer to firmware configuration
@param[in] Size Size in bytes to write
@param[in] Buffer Buffer to transfer data from (OPTIONAL if Size is 0)
**/
typedef
VOID (EFIAPI WRITE_BYTES_FUNCTION) (
IN UINTN Size,
IN VOID *Buffer OPTIONAL
);
//
// Forward declaration of the two implementations we have.
//
STATIC READ_BYTES_FUNCTION MmioReadBytes;
STATIC WRITE_BYTES_FUNCTION MmioWriteBytes;
STATIC READ_BYTES_FUNCTION DmaReadBytes;
STATIC WRITE_BYTES_FUNCTION DmaWriteBytes;
//
// This points to the one we detect at runtime.
// These correspond to the implementation we detect at runtime.
//
STATIC READ_BYTES_FUNCTION *InternalQemuFwCfgReadBytes = MmioReadBytes;
STATIC WRITE_BYTES_FUNCTION *InternalQemuFwCfgWriteBytes = MmioWriteBytes;
/**
@ -166,6 +182,7 @@ QemuFwCfgInitialize (
if ((Features & FW_CFG_F_DMA) != 0) {
mFwCfgDmaAddress = FwCfgDmaAddress;
InternalQemuFwCfgReadBytes = DmaReadBytes;
InternalQemuFwCfgWriteBytes = DmaWriteBytes;
}
}
} else {
@ -358,6 +375,41 @@ QemuFwCfgReadBytes (
}
}
/**
Slow WRITE_BYTES_FUNCTION.
**/
STATIC
VOID
EFIAPI
MmioWriteBytes (
IN UINTN Size,
IN VOID *Buffer OPTIONAL
)
{
UINTN Idx;
for (Idx = 0; Idx < Size; ++Idx) {
MmioWrite8 (mFwCfgDataAddress, ((UINT8 *)Buffer)[Idx]);
}
}
/**
Fast WRITE_BYTES_FUNCTION.
**/
STATIC
VOID
EFIAPI
DmaWriteBytes (
IN UINTN Size,
IN VOID *Buffer OPTIONAL
)
{
DmaTransferBytes (Size, Buffer, FW_CFG_DMA_CTL_WRITE);
}
/**
Write firmware configuration bytes from a buffer
@ -376,11 +428,7 @@ QemuFwCfgWriteBytes (
)
{
if (QemuFwCfgIsAvailable ()) {
UINTN Idx;
for (Idx = 0; Idx < Size; ++Idx) {
MmioWrite8 (mFwCfgDataAddress, ((UINT8 *)Buffer)[Idx]);
}
InternalQemuFwCfgWriteBytes (Size, Buffer);
}
}