OvmfPkg/QemuVideoDxe/UnalignedIoMsc.c

   1 /** @file
   2   Unaligned port I/O. This file has compiler specifics for Microsoft C as there
   3   is no ANSI C standard for doing IO.
   4
   5   Based on IoLibMsc.c
   6
   7   Copyright (c) 2006 - 2010, Intel Corporation. All rights reserved.<BR>
   8   This program and the accompanying materials are licensed and made available
   9   under the terms and conditions of the BSD License which accompanies this
  10   distribution.  The full text of the license may be found at
  11   http://opensource.org/licenses/bsd-license.php.
  12
  13   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  14   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  15
  16 **/
  17
  18
  19 #include "UnalignedIoInternal.h"
  20
  21 unsigned long  _inpd (unsigned short port);
  22 unsigned long  _outpd (unsigned short port, unsigned long dataword );
  23 void          _ReadWriteBarrier (void);
  24
  25 /**
  26   Performs a 32-bit write to the specified, possibly unaligned I/O-type
  27   address.
  28
  29   Writes the 32-bit I/O port specified by Port with the value specified by
  30   Value and returns Value. This function must guarantee that all I/O read and
  31   write operations are serialized.
  32
  33   If 32-bit unaligned I/O port operations are not supported, then ASSERT().
  34
  35   @param[in]  Port   I/O port address
  36   @param[in]  Value  32-bit word to write
  37
  38   @return The value written to the I/O port.
  39
  40 **/
  41 UINT32
  42 UnalignedIoWrite32 (
  43   IN      UINTN                     Port,
  44   IN      UINT32                    Value
  45   )
  46 {
  47   _ReadWriteBarrier ();
  48   _outpd ((UINT16)Port, Value);
  49   _ReadWriteBarrier ();
  50   return Value;
  51 }
  52
  53 /**
  54   Reads a 32-bit word from the specified, possibly unaligned I/O-type address.
  55
  56   Reads the 32-bit I/O port specified by Port. The 32-bit read value is
  57   returned. This function must guarantee that all I/O read and write operations
  58   are serialized.
  59
  60   If 32-bit unaligned I/O port operations are not supported, then ASSERT().
  61
  62   @param[in]  Port  The I/O port to read.
  63
  64   @return The value read.
  65
  66 **/
  67 UINT32
  68 UnalignedIoRead32 (
  69   IN      UINTN                     Port
  70   )
  71 {
  72   UINT32                            Value;
  73
  74   _ReadWriteBarrier ();
  75   Value = _inpd ((UINT16)Port);
  76   _ReadWriteBarrier ();
  77   return Value;
  78 }