05a5379458
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>
60 lines
1.8 KiB
C
60 lines
1.8 KiB
C
/** @file
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Unaligned port I/O, with implementations for various x86 compilers and a
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dummy for platforms which do not support unaligned port I/O.
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Copyright (c) 2017, Phil Dennis-Jordan.<BR>
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This program and the accompanying materials are licensed and made available
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under the terms and conditions of the BSD License which accompanies this
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distribution. The full text of the license may be found at
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http://opensource.org/licenses/bsd-license.php.
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THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
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WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
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**/
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#ifndef _UNALIGNED_IO_INTERNAL_H_
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#define _UNALIGNED_IO_INTERNAL_H_
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/**
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Performs a 32-bit write to the specified, possibly unaligned I/O-type address.
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Writes the 32-bit I/O port specified by Port with the value specified by Value
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and returns Value. This function must guarantee that all I/O read and write
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operations are serialized.
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If 32-bit unaligned I/O port operations are not supported, then ASSERT().
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@param[in] Port I/O port address
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@param[in] Value 32-bit word to write
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@return The value written to the I/O port.
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**/
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UINT32
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UnalignedIoWrite32 (
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IN UINTN Port,
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IN UINT32 Value
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);
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/**
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Reads a 32-bit word from the specified, possibly unaligned I/O-type address.
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Reads the 32-bit I/O port specified by Port. The 32-bit read value is
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returned. This function must guarantee that all I/O read and write operations
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are serialized.
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If 32-bit unaligned I/O port operations are not supported, then ASSERT().
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@param[in] Port The I/O port to read.
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@return The value read.
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**/
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UINT32
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UnalignedIoRead32 (
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IN UINTN Port
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);
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#endif
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