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| author | Phil Dennis-Jordan <phil@philjordan.eu> | 2017-04-07 18:25:57 +1200 |
|---|---|---|
| committer | Laszlo Ersek <lersek@redhat.com> | 2017-04-07 12:22:30 +0200 |
| commit | 05a5379458725234de8a05780fcb5da2c12680e4 (patch) | |
| tree | 1513828a075954852173baa3b3a0d2b8574c02d2 /OvmfPkg/QemuVideoDxe/UnalignedIoGcc.c | |
| parent | 9bcca53fe466cdff397578328d9d87d257aba493 (diff) | |
| download | edk2-05a5379458725234de8a05780fcb5da2c12680e4.tar.gz edk2-05a5379458725234de8a05780fcb5da2c12680e4.tar.bz2 edk2-05a5379458725234de8a05780fcb5da2c12680e4.zip | |
OvmfPkg/QemuVideoDxe: Helper functions for unaligned port I/O.
The VMWare SVGA display device implemented by Qemu (-vga vmware) uses
an I/O-type BAR which is laid out such that some register offsets are
not aligned to the read/write width with which they are expected to be
accessed. (The register value port has an offset of 1 and requires
32 bit wide read/write access.)
The EFI_PCI_IO_PROTOCOL's Io.Read/Io.Write functions do not support
such unaligned I/O.
Before a driver for this device can be added to QemuVideoDxe, helper
functions for unaligned I/O are therefore required. This adds the
functions UnalignedIoWrite32 and UnalignedIoRead32, based on IoLib's
IoWrite32 and IoRead32, for the Ia32 and X64 architectures. Port I/O
requires inline assembly, so implementations are provided for the GCC,
ICC, and Microsoft compiler families. Such I/O is not possible on other
architectures, a dummy (ASSERT()ing) implementation is therefore
provided to satisfy the linker.
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Suggested-by: Jordan Justen <jordan.l.justen@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Phil Dennis-Jordan <phil@philjordan.eu>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Diffstat (limited to 'OvmfPkg/QemuVideoDxe/UnalignedIoGcc.c')
| -rw-r--r-- | OvmfPkg/QemuVideoDxe/UnalignedIoGcc.c | 70 |
1 files changed, 70 insertions, 0 deletions
diff --git a/OvmfPkg/QemuVideoDxe/UnalignedIoGcc.c b/OvmfPkg/QemuVideoDxe/UnalignedIoGcc.c new file mode 100644 index 0000000000..105d55d3b9 --- /dev/null +++ b/OvmfPkg/QemuVideoDxe/UnalignedIoGcc.c @@ -0,0 +1,70 @@ +/** @file
+ Unaligned Port I/O. This file has compiler specifics for GCC as there is no
+ ANSI C standard for doing IO.
+
+ Based on IoLibGcc.c.
+
+ Copyright (c) 2006 - 2010, Intel Corporation. All rights reserved.<BR>
+ This program and the accompanying materials are licensed and made available
+ under the terms and conditions of the BSD License which accompanies this
+ distribution. The full text of the license may be found at
+ http://opensource.org/licenses/bsd-license.php.
+
+ THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+
+**/
+
+
+#include "UnalignedIoInternal.h"
+
+/**
+ Performs a 32-bit write to the specified, possibly unaligned I/O-type
+ address.
+
+ Writes the 32-bit I/O port specified by Port with the value specified by
+ Value and returns Value. This function must guarantee that all I/O read and
+ write operations are serialized.
+
+ If 32-bit unaligned I/O port operations are not supported, then ASSERT().
+
+ @param[in] Port I/O port address
+ @param[in] Value 32-bit word to write
+
+ @return The value written to the I/O port.
+
+**/
+UINT32
+UnalignedIoWrite32 (
+ IN UINTN Port,
+ IN UINT32 Value
+ )
+{
+ __asm__ __volatile__ ( "outl %0, %1" : : "a" (Value), "d" ((UINT16)Port) );
+ return Value;
+}
+
+/**
+ Reads a 32-bit word from the specified, possibly unaligned I/O-type address.
+
+ Reads the 32-bit I/O port specified by Port. The 32-bit read value is
+ returned. This function must guarantee that all I/O read and write operations
+ are serialized.
+
+ If 32-bit unaligned I/O port operations are not supported, then ASSERT().
+
+ @param[in] Port The I/O port to read.
+
+ @return The value read.
+
+**/
+UINT32
+UnalignedIoRead32 (
+ IN UINTN Port
+ )
+{
+ UINT32 Data;
+ __asm__ __volatile__ ( "inl %1, %0" : "=a" (Data) : "d" ((UINT16)Port) );
+ return Data;
+}
+
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