OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgNull.c

   1 /** @file
   2
   3   Null implementation of the fw_cfg library.
   4
   5   Copyright (C) 2020, Rebecca Cran <rebecca@bsdio.com>
   6   Copyright (C) 2013, Red Hat, Inc.
   7   Copyright (c) 2011 - 2013, Intel Corporation. All rights reserved.<BR>
   8   Copyright (c) 2017, Advanced Micro Devices. All rights reserved.<BR>
   9
  10   SPDX-License-Identifier: BSD-2-Clause-Patent
  11 **/
  12
  13 #include <Library/DebugLib.h>
  14 #include <Library/QemuFwCfgLib.h>
  15
  16 /**
  17   Returns a boolean indicating if the firmware configuration interface
  18   is available or not.
  19
  20   This function may change fw_cfg state.
  21
  22   @retval    TRUE   The interface is available
  23   @retval    FALSE  The interface is not available
  24
  25 **/
  26 BOOLEAN
  27 EFIAPI
  28 QemuFwCfgIsAvailable (
  29   VOID
  30   )
  31 {
  32   return FALSE;
  33 }
  34
  35
  36 /**
  37   Selects a firmware configuration item for reading.
  38
  39   Following this call, any data read from this item will start from
  40   the beginning of the configuration item's data.
  41
  42   @param[in] QemuFwCfgItem - Firmware Configuration item to read
  43
  44 **/
  45 VOID
  46 EFIAPI
  47 QemuFwCfgSelectItem (
  48   IN FIRMWARE_CONFIG_ITEM   QemuFwCfgItem
  49   )
  50 {
  51   ASSERT (FALSE);
  52 }
  53
  54
  55 /**
  56   Reads firmware configuration bytes into a buffer
  57
  58   If called multiple times, then the data read will
  59   continue at the offset of the firmware configuration
  60   item where the previous read ended.
  61
  62   @param[in] Size - Size in bytes to read
  63   @param[in] Buffer - Buffer to store data into
  64
  65 **/
  66 VOID
  67 EFIAPI
  68 QemuFwCfgReadBytes (
  69   IN UINTN                  Size,
  70   IN VOID                   *Buffer  OPTIONAL
  71   )
  72 {
  73   ASSERT (FALSE);
  74 }
  75
  76
  77 /**
  78   Writes firmware configuration bytes from a buffer
  79
  80   If called multiple times, then the data written will
  81   continue at the offset of the firmware configuration
  82   item where the previous write ended.
  83
  84   @param[in] Size - Size in bytes to write
  85   @param[in] Buffer - Buffer to read data from
  86
  87 **/
  88 VOID
  89 EFIAPI
  90 QemuFwCfgWriteBytes (
  91   IN UINTN                  Size,
  92   IN VOID                   *Buffer
  93   )
  94 {
  95   ASSERT (FALSE);
  96 }
  97
  98
  99 /**
 100   Skip bytes in the firmware configuration item.
 101
 102   Increase the offset of the firmware configuration item without transferring
 103   bytes between the item and a caller-provided buffer. Subsequent read, write
 104   or skip operations will commence at the increased offset.
 105
 106   @param[in] Size  Number of bytes to skip.
 107 **/
 108 VOID
 109 EFIAPI
 110 QemuFwCfgSkipBytes (
 111   IN UINTN                  Size
 112   )
 113 {
 114   ASSERT (FALSE);
 115 }
 116
 117
 118 /**
 119   Reads a UINT8 firmware configuration value
 120
 121   @return    Value of Firmware Configuration item read
 122
 123 **/
 124 UINT8
 125 EFIAPI
 126 QemuFwCfgRead8 (
 127   VOID
 128   )
 129 {
 130   ASSERT (FALSE);
 131   return 0;
 132 }
 133
 134
 135 /**
 136   Reads a UINT16 firmware configuration value
 137
 138   @return    Value of Firmware Configuration item read
 139
 140 **/
 141 UINT16
 142 EFIAPI
 143 QemuFwCfgRead16 (
 144   VOID
 145   )
 146 {
 147   ASSERT (FALSE);
 148   return 0;
 149 }
 150
 151
 152 /**
 153   Reads a UINT32 firmware configuration value
 154
 155   @return    Value of Firmware Configuration item read
 156
 157 **/
 158 UINT32
 159 EFIAPI
 160 QemuFwCfgRead32 (
 161   VOID
 162   )
 163 {
 164   ASSERT (FALSE);
 165   return 0;
 166 }
 167
 168
 169 /**
 170   Reads a UINT64 firmware configuration value
 171
 172   @return    Value of Firmware Configuration item read
 173
 174 **/
 175 UINT64
 176 EFIAPI
 177 QemuFwCfgRead64 (
 178   VOID
 179   )
 180 {
 181   ASSERT (FALSE);
 182   return 0;
 183 }
 184
 185
 186 /**
 187   Find the configuration item corresponding to the firmware configuration file.
 188
 189   @param[in]  Name - Name of file to look up.
 190   @param[out] Item - Configuration item corresponding to the file, to be passed
 191                      to QemuFwCfgSelectItem ().
 192   @param[out] Size - Number of bytes in the file.
 193
 194   @return    RETURN_SUCCESS       If file is found.
 195              RETURN_NOT_FOUND     If file is not found.
 196              RETURN_UNSUPPORTED   If firmware configuration is unavailable.
 197
 198 **/
 199 RETURN_STATUS
 200 EFIAPI
 201 QemuFwCfgFindFile (
 202   IN   CONST CHAR8           *Name,
 203   OUT  FIRMWARE_CONFIG_ITEM  *Item,
 204   OUT  UINTN                 *Size
 205   )
 206 {
 207   return RETURN_UNSUPPORTED;
 208 }
 209