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   Selects a firmware configuration item for reading.
  37
  38   Following this call, any data read from this item will start from
  39   the beginning of the configuration item's data.
  40
  41   @param[in] QemuFwCfgItem - Firmware Configuration item to read
  42
  43 **/
  44 VOID
  45 EFIAPI
  46 QemuFwCfgSelectItem (
  47   IN FIRMWARE_CONFIG_ITEM  QemuFwCfgItem
  48   )
  49 {
  50   ASSERT (FALSE);
  51 }
  52
  53 /**
  54   Reads firmware configuration bytes into a buffer
  55
  56   If called multiple times, then the data read will
  57   continue at the offset of the firmware configuration
  58   item where the previous read ended.
  59
  60   @param[in] Size - Size in bytes to read
  61   @param[in] Buffer - Buffer to store data into
  62
  63 **/
  64 VOID
  65 EFIAPI
  66 QemuFwCfgReadBytes (
  67   IN UINTN  Size,
  68   IN VOID   *Buffer  OPTIONAL
  69   )
  70 {
  71   ASSERT (FALSE);
  72 }
  73
  74 /**
  75   Writes firmware configuration bytes from a buffer
  76
  77   If called multiple times, then the data written will
  78   continue at the offset of the firmware configuration
  79   item where the previous write ended.
  80
  81   @param[in] Size - Size in bytes to write
  82   @param[in] Buffer - Buffer to read data from
  83
  84 **/
  85 VOID
  86 EFIAPI
  87 QemuFwCfgWriteBytes (
  88   IN UINTN  Size,
  89   IN VOID   *Buffer
  90   )
  91 {
  92   ASSERT (FALSE);
  93 }
  94
  95 /**
  96   Skip bytes in the firmware configuration item.
  97
  98   Increase the offset of the firmware configuration item without transferring
  99   bytes between the item and a caller-provided buffer. Subsequent read, write
 100   or skip operations will commence at the increased offset.
 101
 102   @param[in] Size  Number of bytes to skip.
 103 **/
 104 VOID
 105 EFIAPI
 106 QemuFwCfgSkipBytes (
 107   IN UINTN  Size
 108   )
 109 {
 110   ASSERT (FALSE);
 111 }
 112
 113 /**
 114   Reads a UINT8 firmware configuration value
 115
 116   @return    Value of Firmware Configuration item read
 117
 118 **/
 119 UINT8
 120 EFIAPI
 121 QemuFwCfgRead8 (
 122   VOID
 123   )
 124 {
 125   ASSERT (FALSE);
 126   return 0;
 127 }
 128
 129 /**
 130   Reads a UINT16 firmware configuration value
 131
 132   @return    Value of Firmware Configuration item read
 133
 134 **/
 135 UINT16
 136 EFIAPI
 137 QemuFwCfgRead16 (
 138   VOID
 139   )
 140 {
 141   ASSERT (FALSE);
 142   return 0;
 143 }
 144
 145 /**
 146   Reads a UINT32 firmware configuration value
 147
 148   @return    Value of Firmware Configuration item read
 149
 150 **/
 151 UINT32
 152 EFIAPI
 153 QemuFwCfgRead32 (
 154   VOID
 155   )
 156 {
 157   ASSERT (FALSE);
 158   return 0;
 159 }
 160
 161 /**
 162   Reads a UINT64 firmware configuration value
 163
 164   @return    Value of Firmware Configuration item read
 165
 166 **/
 167 UINT64
 168 EFIAPI
 169 QemuFwCfgRead64 (
 170   VOID
 171   )
 172 {
 173   ASSERT (FALSE);
 174   return 0;
 175 }
 176
 177 /**
 178   Find the configuration item corresponding to the firmware configuration file.
 179
 180   @param[in]  Name - Name of file to look up.
 181   @param[out] Item - Configuration item corresponding to the file, to be passed
 182                      to QemuFwCfgSelectItem ().
 183   @param[out] Size - Number of bytes in the file.
 184
 185   @return    RETURN_SUCCESS       If file is found.
 186              RETURN_NOT_FOUND     If file is not found.
 187              RETURN_UNSUPPORTED   If firmware configuration is unavailable.
 188
 189 **/
 190 RETURN_STATUS
 191 EFIAPI
 192 QemuFwCfgFindFile (
 193   IN   CONST CHAR8           *Name,
 194   OUT  FIRMWARE_CONFIG_ITEM  *Item,
 195   OUT  UINTN                 *Size
 196   )
 197 {
 198   return RETURN_UNSUPPORTED;
 199 }