OvmfPkg/Library/QemuFwCfgS3Lib/QemuFwCfgS3Base.c

   1 /** @file
   2   Base Null library instance of the QemuFwCfgS3Lib class.
   3
   4   This library instance returns constant FALSE from QemuFwCfgS3Enabled(), and
   5   all other library functions trigger assertion failures. It is suitable for
   6   QEMU targets and machine types that never enable S3.
   7
   8   Copyright (C) 2017, Red Hat, Inc.
   9
  10   SPDX-License-Identifier: BSD-2-Clause-Patent
  11 **/
  12
  13 #include <Library/DebugLib.h>
  14 #include <Library/QemuFwCfgS3Lib.h>
  15
  16 /**
  17   Determine if S3 support is explicitly enabled.
  18
  19   @retval  TRUE   If S3 support is explicitly enabled. Other functions in this
  20                   library may be called (subject to their individual
  21                   restrictions).
  22
  23            FALSE  Otherwise. This includes unavailability of the firmware
  24                   configuration interface. No other function in this library
  25                   must be called.
  26 **/
  27 BOOLEAN
  28 EFIAPI
  29 QemuFwCfgS3Enabled (
  30   VOID
  31   )
  32 {
  33   return FALSE;
  34 }
  35
  36 /**
  37   Install the client module's FW_CFG_BOOT_SCRIPT_CALLBACK_FUNCTION callback for
  38   when the production of ACPI S3 Boot Script opcodes becomes possible.
  39
  40   Take ownership of the client-provided Context, and pass it to the callback
  41   function, when the latter is invoked.
  42
  43   Allocate scratch space for those ACPI S3 Boot Script opcodes to work upon
  44   that the client will produce in the callback function.
  45
  46   @param[in] Callback           FW_CFG_BOOT_SCRIPT_CALLBACK_FUNCTION to invoke
  47                                 when the production of ACPI S3 Boot Script
  48                                 opcodes becomes possible. Callback() may be
  49                                 called immediately from
  50                                 QemuFwCfgS3CallWhenBootScriptReady().
  51
  52   @param[in,out] Context        Client-provided data structure for the
  53                                 Callback() callback function to consume.
  54
  55                                 If Context points to dynamically allocated
  56                                 memory, then Callback() must release it.
  57
  58                                 If Context points to dynamically allocated
  59                                 memory, and
  60                                 QemuFwCfgS3CallWhenBootScriptReady() returns
  61                                 successfully, then the caller of
  62                                 QemuFwCfgS3CallWhenBootScriptReady() must
  63                                 neither dereference nor even evaluate Context
  64                                 any longer, as ownership of the referenced area
  65                                 has been transferred to Callback().
  66
  67   @param[in] ScratchBufferSize  The size of the scratch buffer that will hold,
  68                                 in reserved memory, all client data read,
  69                                 written, and checked by the ACPI S3 Boot Script
  70                                 opcodes produced by Callback().
  71
  72   @retval RETURN_UNSUPPORTED       The library instance does not support this
  73                                    function.
  74
  75   @retval RETURN_NOT_FOUND         The fw_cfg DMA interface to QEMU is
  76                                    unavailable.
  77
  78   @retval RETURN_BAD_BUFFER_SIZE   ScratchBufferSize is too large.
  79
  80   @retval RETURN_OUT_OF_RESOURCES  Memory allocation failed.
  81
  82   @retval RETURN_SUCCESS           Callback() has been installed, and the
  83                                    ownership of Context has been transferred.
  84                                    Reserved memory has been allocated for the
  85                                    scratch buffer.
  86
  87                                    A successful invocation of
  88                                    QemuFwCfgS3CallWhenBootScriptReady() cannot
  89                                    be rolled back.
  90
  91   @return                          Error codes from underlying functions.
  92 **/
  93 RETURN_STATUS
  94 EFIAPI
  95 QemuFwCfgS3CallWhenBootScriptReady (
  96   IN     FW_CFG_BOOT_SCRIPT_CALLBACK_FUNCTION  *Callback,
  97   IN OUT VOID                                  *Context           OPTIONAL,
  98   IN     UINTN                                 ScratchBufferSize
  99   )
 100 {
 101   ASSERT (FALSE);
 102   return RETURN_UNSUPPORTED;
 103 }