MdePkg/Library/BaseIoLibIntrinsic/IoLibGcc.c

   1 /** @file
   2   I/O Library. This file has compiler specifics for GCC as there is no
   3   ANSI C standard for doing IO.
   4
   5   GCC - uses EFIAPI assembler. __asm__ calls GAS. __volatile__ makes sure the
   6   compiler puts the assembler in this exact location. The complex GNUC
   7   operations are not optimzed. It would be possible to also write these
   8   with EFIAPI assembler.
   9
  10   We don't advocate putting compiler specifics in libraries or drivers but there
  11   is no other way to make this work.
  12
  13   Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>
  14   SPDX-License-Identifier: BSD-2-Clause-Patent
  15
  16 **/
  17
  18
  19 #include "BaseIoLibIntrinsicInternal.h"
  20
  21 /**
  22   Reads an 8-bit I/O port.
  23
  24   Reads the 8-bit I/O port specified by Port. The 8-bit read value is returned.
  25   This function must guarantee that all I/O read and write operations are
  26   serialized.
  27
  28   If 8-bit I/O port operations are not supported, then ASSERT().
  29
  30   @param  Port  The I/O port to read.
  31
  32   @return The value read.
  33
  34 **/
  35 UINT8
  36 EFIAPI
  37 IoRead8 (
  38   IN      UINTN                     Port
  39   )
  40 {
  41   UINT8   Data;
  42
  43   __asm__ __volatile__ ("inb %w1,%b0" : "=a" (Data) : "d" ((UINT16)Port));
  44   return Data;
  45 }
  46
  47 /**
  48   Writes an 8-bit I/O port.
  49
  50   Writes the 8-bit I/O port specified by Port with the value specified by Value
  51   and returns Value. This function must guarantee that all I/O read and write
  52   operations are serialized.
  53
  54   If 8-bit I/O port operations are not supported, then ASSERT().
  55
  56   @param  Port  The I/O port to write.
  57   @param  Value The value to write to the I/O port.
  58
  59   @return The value written the I/O port.
  60
  61 **/
  62 UINT8
  63 EFIAPI
  64 IoWrite8 (
  65   IN      UINTN                     Port,
  66   IN      UINT8                     Value
  67   )
  68 {
  69   __asm__ __volatile__ ("outb %b0,%w1" : : "a" (Value), "d" ((UINT16)Port));
  70   return Value;;
  71 }
  72
  73 /**
  74   Reads a 16-bit I/O port.
  75
  76   Reads the 16-bit I/O port specified by Port. The 16-bit read value is returned.
  77   This function must guarantee that all I/O read and write operations are
  78   serialized.
  79
  80   If 16-bit I/O port operations are not supported, then ASSERT().
  81   If Port is not aligned on a 16-bit boundary, then ASSERT().
  82
  83   @param  Port  The I/O port to read.
  84
  85   @return The value read.
  86
  87 **/
  88 UINT16
  89 EFIAPI
  90 IoRead16 (
  91   IN      UINTN                     Port
  92   )
  93 {
  94   UINT16   Data;
  95
  96   ASSERT ((Port & 1) == 0);
  97   __asm__ __volatile__ ("inw %w1,%w0" : "=a" (Data) : "d" ((UINT16)Port));
  98   return Data;
  99 }
 100
 101 /**
 102   Writes a 16-bit I/O port.
 103
 104   Writes the 16-bit I/O port specified by Port with the value specified by Value
 105   and returns Value. This function must guarantee that all I/O read and write
 106   operations are serialized.
 107
 108   If 16-bit I/O port operations are not supported, then ASSERT().
 109   If Port is not aligned on a 16-bit boundary, then ASSERT().
 110
 111   @param  Port  The I/O port to write.
 112   @param  Value The value to write to the I/O port.
 113
 114   @return The value written the I/O port.
 115
 116 **/
 117 UINT16
 118 EFIAPI
 119 IoWrite16 (
 120   IN      UINTN                     Port,
 121   IN      UINT16                    Value
 122   )
 123 {
 124   ASSERT ((Port & 1) == 0);
 125   __asm__ __volatile__ ("outw %w0,%w1" : : "a" (Value), "d" ((UINT16)Port));
 126   return Value;;
 127 }
 128
 129 /**
 130   Reads a 32-bit I/O port.
 131
 132   Reads the 32-bit I/O port specified by Port. The 32-bit read value is returned.
 133   This function must guarantee that all I/O read and write operations are
 134   serialized.
 135
 136   If 32-bit I/O port operations are not supported, then ASSERT().
 137   If Port is not aligned on a 32-bit boundary, then ASSERT().
 138
 139   @param  Port  The I/O port to read.
 140
 141   @return The value read.
 142
 143 **/
 144 UINT32
 145 EFIAPI
 146 IoRead32 (
 147   IN      UINTN                     Port
 148   )
 149 {
 150   UINT32   Data;
 151
 152   ASSERT ((Port & 3) == 0);
 153   __asm__ __volatile__ ("inl %w1,%0" : "=a" (Data) : "d" ((UINT16)Port));
 154   return Data;
 155 }
 156
 157 /**
 158   Writes a 32-bit I/O port.
 159
 160   Writes the 32-bit I/O port specified by Port with the value specified by Value
 161   and returns Value. This function must guarantee that all I/O read and write
 162   operations are serialized.
 163
 164   If 32-bit I/O port operations are not supported, then ASSERT().
 165   If Port is not aligned on a 32-bit boundary, then ASSERT().
 166
 167   @param  Port  The I/O port to write.
 168   @param  Value The value to write to the I/O port.
 169
 170   @return The value written the I/O port.
 171
 172 **/
 173 UINT32
 174 EFIAPI
 175 IoWrite32 (
 176   IN      UINTN                     Port,
 177   IN      UINT32                    Value
 178   )
 179 {
 180   ASSERT ((Port & 3) == 0);
 181   __asm__ __volatile__ ("outl %0,%w1" : : "a" (Value), "d" ((UINT16)Port));
 182   return Value;
 183 }
 184