OvmfPkg/QemuVideoDxe/UnalignedIoGcc.c

   1 /** @file
   2   Unaligned Port I/O. This file has compiler specifics for GCC as there is no
   3   ANSI C standard for doing IO.
   4
   5   Based on IoLibGcc.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 /**
  22   Performs a 32-bit write to the specified, possibly unaligned I/O-type
  23   address.
  24
  25   Writes the 32-bit I/O port specified by Port with the value specified by
  26   Value and returns Value. This function must guarantee that all I/O read and
  27   write operations are serialized.
  28
  29   If 32-bit unaligned I/O port operations are not supported, then ASSERT().
  30
  31   @param[in]  Port   I/O port address
  32   @param[in]  Value  32-bit word to write
  33
  34   @return The value written to the I/O port.
  35
  36 **/
  37 UINT32
  38 UnalignedIoWrite32 (
  39   IN      UINTN                     Port,
  40   IN      UINT32                    Value
  41   )
  42 {
  43   __asm__ __volatile__ ( "outl %0, %1" : : "a" (Value), "d" ((UINT16)Port) );
  44   return Value;
  45 }
  46
  47 /**
  48   Reads a 32-bit word from the specified, possibly unaligned I/O-type address.
  49
  50   Reads the 32-bit I/O port specified by Port. The 32-bit read value is
  51   returned. This function must guarantee that all I/O read and write operations
  52   are serialized.
  53
  54   If 32-bit unaligned I/O port operations are not supported, then ASSERT().
  55
  56   @param[in]  Port  The I/O port to read.
  57
  58   @return The value read.
  59
  60 **/
  61 UINT32
  62 UnalignedIoRead32 (
  63   IN      UINTN                     Port
  64   )
  65 {
  66   UINT32 Data;
  67   __asm__ __volatile__ ( "inl %1, %0" : "=a" (Data) : "d" ((UINT16)Port) );
  68   return Data;
  69 }
  70