IntelFrameworkPkg/Include/Ppi/ReadOnlyVariable.h

   1 /** @file
   2   This file declares Read-only Variable Service PPI, which is required PPI by framework spec.
   3
   4   These services provide a lightweight, read-only variant of the full EFI variable services. The
   5   reason that these services are read-only is to reduce the complexity of flash management. Also,
   6   some implementation of the PEI may use the same physical flash part for variable and PEIM
   7   storage; as such, a write command to certain technologies would alter the contents of the entire part,
   8   thus making the in situ PEIM execution not follow the required flow.
   9
  10   Copyright (c) 2006 - 2009, Intel Corporation
  11   All rights reserved. This program and the accompanying materials
  12   are licensed and made available under the terms and conditions of the BSD License
  13   which accompanies this distribution.  The full text of the license may be found at
  14   http://opensource.org/licenses/bsd-license.php
  15
  16   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  17   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  18
  19   @par Revision Reference:
  20   This PPI is defined in PEI CIS
  21   Version 0.91.
  22 **/
  23
  24 #ifndef __PEI_READ_ONLY_VARIABLE_PPI_H__
  25 #define __PEI_READ_ONLY_VARIABLE_PPI_H__
  26
  27 #define EFI_PEI_READ_ONLY_VARIABLE_ACCESS_PPI_GUID \
  28   { \
  29     0x3cdc90c6, 0x13fb, 0x4a75, {0x9e, 0x79, 0x59, 0xe9, 0xdd, 0x78, 0xb9, 0xfa } \
  30   }
  31
  32 typedef struct _EFI_PEI_READ_ONLY_VARIABLE_PPI  EFI_PEI_READ_ONLY_VARIABLE_PPI;
  33
  34 ///
  35 /// Variable attributes
  36 ///@{
  37 #define EFI_VARIABLE_NON_VOLATILE       0x00000001
  38 #define EFI_VARIABLE_BOOTSERVICE_ACCESS 0x00000002
  39 #define EFI_VARIABLE_RUNTIME_ACCESS     0x00000004
  40   /**
  41   /// Inconsistent with specification here:
  42   /// In Framework Spec, PeiCis0.91, neither the macro or its value is defined.
  43   /// Keeping this inconsistancy for backward compatibility.
  44   **/
  45 #define EFI_VARIABLE_READ_ONLY          0x00000008
  46 ///@}
  47
  48 /**
  49   Get Variable value by Name and GUID pair
  50
  51   @param[in]  PeiServices    An indirect pointer to the PEI Services Table published by the PEI Foundation.
  52   @param[in]  VariableName   A NULL-terminated Unicode string that is the name of the vendor's variable.
  53   @param[in]  VendorGuid     A unique identifier for the vendor.
  54   @param[out] Attributes     This OPTIONAL parameter may be either NULL or
  55                              a pointer to the location in which to return
  56                              the attributes bitmask for the variable.
  57   @param[in,out]  DataSize   On input, the size in bytes of the return Data buffer.
  58                              On output, the size of data returned in Data.
  59   @param[out] Data           The buffer to return the contents of the variable.
  60
  61   @retval EFI_SUCCESS           The function completed successfully.
  62   @retval EFI_NOT_FOUND         The variable was not found.
  63   @retval EFI_BUFFER_TOO_SMALL  The BufferSize is too small for the result.
  64   @retval EFI_INVALID_PARAMETER One of the parameters has an invalid value.
  65   @retval EFI_DEVICE_ERROR      The variable could not be retrieved due to a hardware error.
  66
  67 **/
  68 typedef
  69 EFI_STATUS
  70 (EFIAPI *EFI_PEI_GET_VARIABLE)(
  71   IN     EFI_PEI_SERVICES   **PeiServices,
  72   IN     CHAR16             *VariableName,
  73   IN     EFI_GUID           *VendorGuid,
  74      OUT UINT32             *Attributes OPTIONAL,
  75   IN OUT UINTN              *DataSize,
  76      OUT VOID               *Data
  77   );
  78
  79 /**
  80   This function can be called multiple times to retrieve the VariableName
  81   and VendorGuid of all variables currently available in the system. On each call
  82   to GetNextVariableName() the previous results are passed into the interface,
  83   and on output the interface returns the next variable name data.  When the
  84   entire variable list has been returned, the error EFI_NOT_FOUND is returned.
  85
  86   @param[in]  PeiServices       An indirect pointer to the PEI Services Table published by the PEI Foundation.
  87   @param[in]  VariableNameSize  The size of the VariableName buffer.
  88   @param[in]  VariableName      On input, supplies the last VariableName that was
  89                                 returned by GetNextVariableName(). On output, returns the Null-terminated
  90                                 Unicode string of the current variable.
  91   @param[in]  VendorGuid        On input, supplies the last VendorGuid that was
  92                                 returned by GetNextVariableName(). On output, returns the VendorGuid
  93                                 of the current variable.
  94
  95   @retval EFI_SUCCESS           The function completed successfully.
  96   @retval EFI_NOT_FOUND         The next variable was not found.
  97   @retval EFI_BUFFER_TOO_SMALL  The VariableNameSize is too small for the result.
  98   @retval EFI_INVALID_PARAMETER One of the parameters has an invalid value.
  99   @retval EFI_DEVICE_ERROR      The variable name could not be retrieved due to a hardware error.
 100
 101 **/
 102 typedef
 103 EFI_STATUS
 104 (EFIAPI *EFI_PEI_GET_NEXT_VARIABLE_NAME)(
 105   IN EFI_PEI_SERVICES             **PeiServices,
 106   IN OUT UINTN                    *VariableNameSize,
 107   IN OUT CHAR16                   *VariableName,
 108   IN OUT EFI_GUID                 *VendorGuid
 109   );
 110
 111 ///
 112 /// This PPI provides a lightweight, read-only variant of the full EFI
 113 /// variable services.
 114 ///
 115 struct _EFI_PEI_READ_ONLY_VARIABLE_PPI {
 116         ///
 117   /// Inconsistent with specification here:
 118   /// In Framework Spec, PeiCis0.91, the field is named as GetVariable and GetNextVariableName.
 119   /// Keeping this inconsistance is for backward compatibility.
 120         ///
 121   EFI_PEI_GET_VARIABLE            PeiGetVariable;         ///< A service to ascertain a given variable name.
 122   EFI_PEI_GET_NEXT_VARIABLE_NAME  PeiGetNextVariableName; ///< A service to ascertain a variable based upon a given, known variable
 123 };
 124
 125 extern EFI_GUID gEfiPeiReadOnlyVariablePpiGuid;
 126
 127 #endif  /* __PEI_READ_ONLY_VARIABLE_PPI_H__ */
 128