From d055601ea7dc7cc09338445188ba18482365c2a1 Mon Sep 17 00:00:00 2001 From: Laszlo Ersek Date: Fri, 27 Jan 2017 05:49:03 +0100 Subject: OvmfPkg/QemuFwCfgLib: generalize InternalQemuFwCfgDmaBytes() to SKIP op The fw_cfg DMA interface provides a simple method to skip over bytes in an fw_cfg blob before reading or writing more bytes. InternalQemuFwCfgDmaBytes() can support it easily, we just have to expose the Control parameter more flexibly than the current "Write" BOOLEAN. Cc: Jordan Justen Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=359 Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek Reviewed-by: Ard Biesheuvel Reviewed-by: Jordan Justen --- OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c | 31 ++++++++++++++++++----------- 1 file changed, 19 insertions(+), 12 deletions(-) (limited to 'OvmfPkg') diff --git a/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c index a228c029df..6b6b2c7726 100644 --- a/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c +++ b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c @@ -47,32 +47,39 @@ QemuFwCfgSelectItem ( /** - Transfer an array of bytes using the DMA interface. + Transfer an array of bytes, or skip a number of bytes, using the DMA + interface. - @param[in] Size Size in bytes to transfer. - @param[in,out] Buffer Buffer to read data into or write data from. May be - NULL if Size is zero. - @param[in] Write TRUE if writing to fw_cfg from Buffer, FALSE if - reading from fw_cfg into Buffer. + @param[in] Size Size in bytes to transfer or skip. + + @param[in,out] Buffer Buffer to read data into or write data from. Ignored, + and may be NULL, if Size is zero, or Control is + FW_CFG_DMA_CTL_SKIP. + + @param[in] Control One of the following: + FW_CFG_DMA_CTL_WRITE - write to fw_cfg from Buffer. + FW_CFG_DMA_CTL_READ - read from fw_cfg into Buffer. + FW_CFG_DMA_CTL_SKIP - skip bytes in fw_cfg. **/ VOID InternalQemuFwCfgDmaBytes ( IN UINT32 Size, IN OUT VOID *Buffer OPTIONAL, - IN BOOLEAN Write + IN UINT32 Control ) { volatile FW_CFG_DMA_ACCESS Access; UINT32 AccessHigh, AccessLow; UINT32 Status; + ASSERT (Control == FW_CFG_DMA_CTL_WRITE || Control == FW_CFG_DMA_CTL_READ || + Control == FW_CFG_DMA_CTL_SKIP); + if (Size == 0) { return; } - Access.Control = SwapBytes32 ( - Write ? FW_CFG_DMA_CTL_WRITE : FW_CFG_DMA_CTL_READ - ); + Access.Control = SwapBytes32 (Control); Access.Length = SwapBytes32 (Size); Access.Address = SwapBytes64 ((UINTN)Buffer); @@ -125,7 +132,7 @@ InternalQemuFwCfgReadBytes ( ) { if (InternalQemuFwCfgDmaIsAvailable () && Size <= MAX_UINT32) { - InternalQemuFwCfgDmaBytes ((UINT32)Size, Buffer, FALSE); + InternalQemuFwCfgDmaBytes ((UINT32)Size, Buffer, FW_CFG_DMA_CTL_READ); return; } IoReadFifo8 (0x511, Size, Buffer); @@ -177,7 +184,7 @@ QemuFwCfgWriteBytes ( { if (InternalQemuFwCfgIsAvailable ()) { if (InternalQemuFwCfgDmaIsAvailable () && Size <= MAX_UINT32) { - InternalQemuFwCfgDmaBytes ((UINT32)Size, Buffer, TRUE); + InternalQemuFwCfgDmaBytes ((UINT32)Size, Buffer, FW_CFG_DMA_CTL_WRITE); return; } IoWriteFifo8 (0x511, Size, Buffer); -- cgit v1.2.3