diff options
| author | Laszlo Ersek <lersek@redhat.com> | 2017-01-27 08:10:15 +0100 |
|---|---|---|
| committer | Laszlo Ersek <lersek@redhat.com> | 2017-01-31 00:14:41 +0100 |
| commit | 7fcb735412998d536cb348049c4ea60897fa6886 (patch) | |
| tree | 7ce033b78a7c7cc9c5c3c3edd161cc0cb725ed02 /ArmVirtPkg | |
| parent | e8ae381f608ae02662f4dcc7379898162645d2ca (diff) | |
ArmVirtPkg/QemuFwCfgLib: implement QemuFwCfgSkipBytes() API
We are now sufficiently equipped to implement the new QemuFwCfgSkipBytes()
API.
The previous patch and this one enable ArmVirtPkg/QemuFwCfgLib to
overwrite part of a writeable fw_cfg file, which will be particularly
useful for the upcoming QEMU_LOADER_WRITE_POINTER command in
OvmfPkg/AcpiPlatformDxe.
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>
Diffstat (limited to 'ArmVirtPkg')
| -rw-r--r-- | ArmVirtPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c | 78 |
1 files changed, 78 insertions, 0 deletions
diff --git a/ArmVirtPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c b/ArmVirtPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c index 56db908f5c..9dd5c911fc 100644 --- a/ArmVirtPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c +++ b/ArmVirtPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c @@ -55,19 +55,33 @@ VOID (EFIAPI WRITE_BYTES_FUNCTION) ( IN VOID *Buffer OPTIONAL
);
+/**
+ Skips bytes in firmware configuration
+
+ @param[in] Size Size in bytes to skip
+
+**/
+typedef
+VOID (EFIAPI SKIP_BYTES_FUNCTION) (
+ IN UINTN Size
+ );
+
//
// Forward declaration of the two implementations we have.
//
STATIC READ_BYTES_FUNCTION MmioReadBytes;
STATIC WRITE_BYTES_FUNCTION MmioWriteBytes;
+STATIC SKIP_BYTES_FUNCTION MmioSkipBytes;
STATIC READ_BYTES_FUNCTION DmaReadBytes;
STATIC WRITE_BYTES_FUNCTION DmaWriteBytes;
+STATIC SKIP_BYTES_FUNCTION DmaSkipBytes;
//
// These correspond to the implementation we detect at runtime.
//
STATIC READ_BYTES_FUNCTION *InternalQemuFwCfgReadBytes = MmioReadBytes;
STATIC WRITE_BYTES_FUNCTION *InternalQemuFwCfgWriteBytes = MmioWriteBytes;
+STATIC SKIP_BYTES_FUNCTION *InternalQemuFwCfgSkipBytes = MmioSkipBytes;
/**
@@ -183,6 +197,7 @@ QemuFwCfgInitialize ( mFwCfgDmaAddress = FwCfgDmaAddress;
InternalQemuFwCfgReadBytes = DmaReadBytes;
InternalQemuFwCfgWriteBytes = DmaWriteBytes;
+ InternalQemuFwCfgSkipBytes = DmaSkipBytes;
}
}
} else {
@@ -434,6 +449,69 @@ QemuFwCfgWriteBytes ( /**
+ Slow SKIP_BYTES_FUNCTION.
+**/
+STATIC
+VOID
+EFIAPI
+MmioSkipBytes (
+ IN UINTN Size
+ )
+{
+ UINTN ChunkSize;
+ UINT8 SkipBuffer[256];
+
+ //
+ // Emulate the skip by reading data in chunks, and throwing it away. The
+ // implementation below doesn't affect the static data footprint for client
+ // modules. Large skips are not expected, therefore this fallback is not
+ // performance critical. The size of SkipBuffer is thought not to exert a
+ // large pressure on the stack.
+ //
+ while (Size > 0) {
+ ChunkSize = MIN (Size, sizeof SkipBuffer);
+ MmioReadBytes (ChunkSize, SkipBuffer);
+ Size -= ChunkSize;
+ }
+}
+
+
+/**
+ Fast SKIP_BYTES_FUNCTION.
+**/
+STATIC
+VOID
+EFIAPI
+DmaSkipBytes (
+ IN UINTN Size
+ )
+{
+ DmaTransferBytes (Size, NULL, FW_CFG_DMA_CTL_SKIP);
+}
+
+
+/**
+ Skip bytes in the firmware configuration item.
+
+ Increase the offset of the firmware configuration item without transferring
+ bytes between the item and a caller-provided buffer. Subsequent read, write
+ or skip operations will commence at the increased offset.
+
+ @param[in] Size Number of bytes to skip.
+**/
+VOID
+EFIAPI
+QemuFwCfgSkipBytes (
+ IN UINTN Size
+ )
+{
+ if (QemuFwCfgIsAvailable ()) {
+ InternalQemuFwCfgSkipBytes (Size);
+ }
+}
+
+
+/**
Reads a UINT8 firmware configuration value
@return Value of Firmware Configuration item read
|