OvmfPkg/Library/QemuFwCfgS3Lib/QemuFwCfgS3Pei.c

   1 /** @file
   2   Limited functionality QemuFwCfgS3Lib instance, for PEI phase modules.
   3
   4   QemuFwCfgS3Enabled() queries S3 enablement via fw_cfg. Other library APIs
   5   will report lack of support.
   6
   7   Copyright (C) 2017, Red Hat, Inc.
   8
   9   SPDX-License-Identifier: BSD-2-Clause-Patent
  10 **/
  11
  12 #include <Library/QemuFwCfgS3Lib.h>
  13
  14 /**
  15   Install the client module's FW_CFG_BOOT_SCRIPT_CALLBACK_FUNCTION callback for
  16   when the production of ACPI S3 Boot Script opcodes becomes possible.
  17
  18   Take ownership of the client-provided Context, and pass it to the callback
  19   function, when the latter is invoked.
  20
  21   Allocate scratch space for those ACPI S3 Boot Script opcodes to work upon
  22   that the client will produce in the callback function.
  23
  24   @param[in] Callback           FW_CFG_BOOT_SCRIPT_CALLBACK_FUNCTION to invoke
  25                                 when the production of ACPI S3 Boot Script
  26                                 opcodes becomes possible. Callback() may be
  27                                 called immediately from
  28                                 QemuFwCfgS3CallWhenBootScriptReady().
  29
  30   @param[in,out] Context        Client-provided data structure for the
  31                                 Callback() callback function to consume.
  32
  33                                 If Context points to dynamically allocated
  34                                 memory, then Callback() must release it.
  35
  36                                 If Context points to dynamically allocated
  37                                 memory, and
  38                                 QemuFwCfgS3CallWhenBootScriptReady() returns
  39                                 successfully, then the caller of
  40                                 QemuFwCfgS3CallWhenBootScriptReady() must
  41                                 neither dereference nor even evaluate Context
  42                                 any longer, as ownership of the referenced area
  43                                 has been transferred to Callback().
  44
  45   @param[in] ScratchBufferSize  The size of the scratch buffer that will hold,
  46                                 in reserved memory, all client data read,
  47                                 written, and checked by the ACPI S3 Boot Script
  48                                 opcodes produced by Callback().
  49
  50   @retval RETURN_UNSUPPORTED       The library instance does not support this
  51                                    function.
  52
  53   @retval RETURN_NOT_FOUND         The fw_cfg DMA interface to QEMU is
  54                                    unavailable.
  55
  56   @retval RETURN_BAD_BUFFER_SIZE   ScratchBufferSize is too large.
  57
  58   @retval RETURN_OUT_OF_RESOURCES  Memory allocation failed.
  59
  60   @retval RETURN_SUCCESS           Callback() has been installed, and the
  61                                    ownership of Context has been transferred.
  62                                    Reserved memory has been allocated for the
  63                                    scratch buffer.
  64
  65                                    A successful invocation of
  66                                    QemuFwCfgS3CallWhenBootScriptReady() cannot
  67                                    be rolled back.
  68
  69   @return                          Error codes from underlying functions.
  70 **/
  71 RETURN_STATUS
  72 EFIAPI
  73 QemuFwCfgS3CallWhenBootScriptReady (
  74   IN     FW_CFG_BOOT_SCRIPT_CALLBACK_FUNCTION  *Callback,
  75   IN OUT VOID                                  *Context           OPTIONAL,
  76   IN     UINTN                                 ScratchBufferSize
  77   )
  78 {
  79   return RETURN_UNSUPPORTED;
  80 }