MdePkg/Include/Protocol/MmAccess.h

   1 /** @file
   2   EFI MM Access Protocol as defined in the PI 1.5 specification.
   3
   4   This protocol is used to control the visibility of the MMRAM on the platform.
   5   It abstracts the location and characteristics of MMRAM.  The expectation is
   6   that the north bridge or memory controller would publish this protocol.
   7
   8   The principal functionality found in the memory controller includes the following:
   9   - Exposing the MMRAM to all non-MM agents, or the "open" state
  10   - Shrouding the MMRAM to all but the MM agents, or the "closed" state
  11   - Preserving the system integrity, or "locking" the MMRAM, such that the settings cannot be
  12     perturbed by either boot service or runtime agents
  13
  14   Copyright (c) 2017, Intel Corporation. All rights reserved.<BR>
  15   SPDX-License-Identifier: BSD-2-Clause-Patent
  16
  17 **/
  18
  19 #ifndef _MM_ACCESS_H_
  20 #define _MM_ACCESS_H_
  21
  22 #define EFI_MM_ACCESS_PROTOCOL_GUID \
  23   { \
  24      0xc2702b74, 0x800c, 0x4131, {0x87, 0x46, 0x8f, 0xb5, 0xb8, 0x9c, 0xe4, 0xac } \
  25   }
  26
  27
  28 typedef struct _EFI_MM_ACCESS_PROTOCOL  EFI_MM_ACCESS_PROTOCOL;
  29
  30 /**
  31   Opens the MMRAM area to be accessible by a boot-service driver.
  32
  33   This function "opens" MMRAM so that it is visible while not inside of MM. The function should
  34   return EFI_UNSUPPORTED if the hardware does not support hiding of MMRAM. The function
  35   should return EFI_DEVICE_ERROR if the MMRAM configuration is locked.
  36
  37   @param[in] This           The EFI_MM_ACCESS_PROTOCOL instance.
  38
  39   @retval EFI_SUCCESS       The operation was successful.
  40   @retval EFI_UNSUPPORTED   The system does not support opening and closing of MMRAM.
  41   @retval EFI_DEVICE_ERROR  MMRAM cannot be opened, perhaps because it is locked.
  42 **/
  43 typedef
  44 EFI_STATUS
  45 (EFIAPI *EFI_MM_OPEN)(
  46   IN EFI_MM_ACCESS_PROTOCOL  *This
  47   );
  48
  49 /**
  50   Inhibits access to the MMRAM.
  51
  52   This function "closes" MMRAM so that it is not visible while outside of MM. The function should
  53   return EFI_UNSUPPORTED if the hardware does not support hiding of MMRAM.
  54
  55   @param[in] This           The EFI_MM_ACCESS_PROTOCOL instance.
  56
  57   @retval EFI_SUCCESS       The operation was successful.
  58   @retval EFI_UNSUPPORTED   The system does not support opening and closing of MMRAM.
  59   @retval EFI_DEVICE_ERROR  MMRAM cannot be closed.
  60 **/
  61 typedef
  62 EFI_STATUS
  63 (EFIAPI *EFI_MM_CLOSE)(
  64   IN EFI_MM_ACCESS_PROTOCOL  *This
  65   );
  66
  67 /**
  68   Inhibits access to the MMRAM.
  69
  70   This function prohibits access to the MMRAM region.  This function is usually implemented such
  71   that it is a write-once operation.
  72
  73   @param[in] This          The EFI_MM_ACCESS_PROTOCOL instance.
  74
  75   @retval EFI_SUCCESS      The device was successfully locked.
  76   @retval EFI_UNSUPPORTED  The system does not support locking of MMRAM.
  77 **/
  78 typedef
  79 EFI_STATUS
  80 (EFIAPI *EFI_MM_LOCK)(
  81   IN EFI_MM_ACCESS_PROTOCOL  *This
  82   );
  83
  84 /**
  85   Queries the memory controller for the possible regions that will support MMRAM.
  86
  87   @param[in]     This           The EFI_MM_ACCESS_PROTOCOL instance.
  88   @param[in,out] MmramMapSize   A pointer to the size, in bytes, of the MmramMemoryMap buffer.
  89   @param[in,out] MmramMap       A pointer to the buffer in which firmware places the current memory map.
  90
  91   @retval EFI_SUCCESS           The chipset supported the given resource.
  92   @retval EFI_BUFFER_TOO_SMALL  The MmramMap parameter was too small.  The current buffer size
  93                                 needed to hold the memory map is returned in MmramMapSize.
  94 **/
  95 typedef
  96 EFI_STATUS
  97 (EFIAPI *EFI_MM_CAPABILITIES)(
  98   IN CONST EFI_MM_ACCESS_PROTOCOL    *This,
  99   IN OUT UINTN                       *MmramMapSize,
 100   IN OUT EFI_MMRAM_DESCRIPTOR        *MmramMap
 101   );
 102
 103 ///
 104 ///  EFI MM Access Protocol is used to control the visibility of the MMRAM on the platform.
 105 ///  It abstracts the location and characteristics of MMRAM. The platform should report all
 106 ///  MMRAM via EFI_MM_ACCESS_PROTOCOL. The expectation is that the north bridge or memory
 107 ///  controller would publish this protocol.
 108 ///
 109 struct _EFI_MM_ACCESS_PROTOCOL {
 110   EFI_MM_OPEN          Open;
 111   EFI_MM_CLOSE         Close;
 112   EFI_MM_LOCK          Lock;
 113   EFI_MM_CAPABILITIES  GetCapabilities;
 114   ///
 115   /// Indicates the current state of the MMRAM. Set to TRUE if MMRAM is locked.
 116   ///
 117   BOOLEAN               LockState;
 118   ///
 119   /// Indicates the current state of the MMRAM. Set to TRUE if MMRAM is open.
 120   ///
 121   BOOLEAN               OpenState;
 122 };
 123
 124 extern EFI_GUID gEfiMmAccessProtocolGuid;
 125
 126 #endif
 127