/** @file  CorebootSMMStoreDxe.c

  Copyright (c) 2020, 9elements Agency GmbH<BR>

  SPDX-License-Identifier: BSD-2-Clause-Patent

**/
#include <Uefi.h>

#include <Library/DebugLib.h>
#include <Library/BaseLib.h>
#include <Library/BaseMemoryLib.h>
#include <Library/UefiRuntimeLib.h>
#include <Library/SMMStoreLib.h>

/*
 * calls into SMM to use the SMMSTORE implementation for persistent storage.
 * The given cmd and subcmd is in eax and the argument in ebx.
 * On successful invocation the result is in eax.
 */
static UINT32 call_smm(UINT8 cmd, UINT8 subcmd, UINT32 arg) {
  CONST UINT32 eax = ((subcmd << 8) | cmd);
  CONST UINT32 ebx = arg;
  UINT32 res;
  UINTN i;

  /* Retry a few times to make sure it works */
  for (i = 0; i < 5; i++) {
  __asm__ __volatile__ (
    "\toutb %b0, $0xb2\n"
    : "=a" (res)
    : "a" (eax), "b" (ebx)
    : "memory");
    if (res == eax) {
      /**
        There might ba a delay between writing the SMI trigger register and
        entering SMM, in which case the SMI handler will do nothing as only
        synchronous SMIs are handled. In addition when there's no SMI handler
        or the SMMSTORE feature isn't compiled in, no register will be modified.

        As there's no livesign from SMM, just wait a bit for the handler to fire,
        and then try again.
      **/
      for (UINTN j = 0; j < 0x10000; j++) {
        CpuPause();
      }
    } else {
      break;
    }
  }

  return res;
}

#define SMMSTORE_RET_SUCCESS 0
#define SMMSTORE_RET_FAILURE 1
#define SMMSTORE_RET_UNSUPPORTED 2

/* Version 2 only */
#define SMMSTORE_CMD_INIT 4
#define SMMSTORE_CMD_RAW_READ 5
#define SMMSTORE_CMD_RAW_WRITE 6
#define SMMSTORE_CMD_RAW_CLEAR 7

/*
 * This allows the payload to store raw data in the flash regions.
 * This can be used by a FaultTolerantWrite implementation, that uses at least
 * two regions in an A/B update scheme.
 */

#pragma pack(1)
/*
 * Reads a chunk of raw data with size @bufsize from the block specified by
 * @block_id starting at @bufoffset.
 * The read data is placed in @buf.
 *
 * @block_id must be less than num_blocks
 * @bufoffset + @bufsize must be less than block_size
 */
struct smmstore_params_raw_write {
  UINT32 bufsize;
  UINT32 bufoffset;
  UINT32 block_id;
};

/*
 * Writes a chunk of raw data with size @bufsize to the block specified by
 * @block_id starting at @bufoffset.
 *
 * @block_id must be less than num_blocks
 * @bufoffset + @bufsize must be less than block_size
 */
struct smmstore_params_raw_read {
  UINT32 bufsize;
  UINT32 bufoffset;
  UINT32 block_id;
};

/*
 * Erases the specified block.
 *
 * @block_id must be less than num_blocks
 */
struct smmstore_params_raw_clear {
  UINT32 block_id;
};

typedef struct smmstore_comm_buffer {
  union {
    struct smmstore_params_raw_write raw_write;
    struct smmstore_params_raw_read raw_read;
    struct smmstore_params_raw_clear raw_clear;
  };
} SMMSTORE_COMBUF;
#pragma pack(0)

/*
 * A memory buffer to place arguments in.
 */
STATIC SMMSTORE_COMBUF *mArgComBuf;
STATIC UINT32 mArgComBufPhys;

/*
 * Metadata provided by the first stage bootloader.
 */
STATIC SMMSTORE_INFO *mSmmStoreInfo;

/**
  Read from SMMStore

  @param[in] Lba      The starting logical block index to read from.
  @param[in] Offset   Offset into the block at which to begin reading.
  @param[in] NumBytes On input, indicates the requested read size. On
                      output, indicates the actual number of bytes read
  @param[in] Buffer   Pointer to the buffer to read into.

**/
EFI_STATUS
SMMStoreRead (
  IN        EFI_LBA                              Lba,
  IN        UINTN                                Offset,
  IN        UINTN                                *NumBytes,
  IN        UINT8                                *Buffer
  )
{
  UINT32 Result;

  if (!mSmmStoreInfo) {
    return EFI_NO_MEDIA;
  }
  if (Lba >= mSmmStoreInfo->NumBlocks) {
    return EFI_INVALID_PARAMETER;
  }
  if ((*NumBytes + Offset) > mSmmStoreInfo->BlockSize ||
      (*NumBytes + Offset) > mSmmStoreInfo->ComBufferSize) {
    return EFI_INVALID_PARAMETER;
  }

  mArgComBuf->raw_read.bufsize = *NumBytes;
  mArgComBuf->raw_read.bufoffset = Offset;
  mArgComBuf->raw_read.block_id = Lba;

  Result = call_smm(mSmmStoreInfo->ApmCmd, SMMSTORE_CMD_RAW_READ, mArgComBufPhys);
  if (Result == SMMSTORE_RET_FAILURE) {
    return EFI_DEVICE_ERROR;
  } else if (Result == SMMSTORE_RET_UNSUPPORTED) {
    return EFI_UNSUPPORTED;
  } else if (Result != SMMSTORE_RET_SUCCESS) {
    return EFI_NO_RESPONSE;
  }

  CopyMem (Buffer, (VOID *)(UINTN)(mSmmStoreInfo->ComBuffer + Offset), *NumBytes);

  return EFI_SUCCESS;
}


/**
  Write to SMMStore

  @param[in] Lba      The starting logical block index to write to.
  @param[in] Offset   Offset into the block at which to begin writing.
  @param[in] NumBytes On input, indicates the requested write size. On
                      output, indicates the actual number of bytes written
  @param[in] Buffer   Pointer to the data to write.

**/
EFI_STATUS
SMMStoreWrite (
  IN        EFI_LBA                             Lba,
  IN        UINTN                               Offset,
  IN        UINTN                               *NumBytes,
  IN        UINT8                               *Buffer
  )
{
  UINTN             Result;

  if (!mSmmStoreInfo) {
    return EFI_NO_MEDIA;
  }
  if (Lba >= mSmmStoreInfo->NumBlocks) {
    return EFI_INVALID_PARAMETER;
  }
  if ((*NumBytes + Offset) > mSmmStoreInfo->BlockSize ||
      (*NumBytes + Offset) > mSmmStoreInfo->ComBufferSize) {
    return EFI_INVALID_PARAMETER;
  }

  mArgComBuf->raw_write.bufsize = *NumBytes;
  mArgComBuf->raw_write.bufoffset = Offset;
  mArgComBuf->raw_write.block_id = Lba;

  CopyMem ((VOID *)(UINTN)(mSmmStoreInfo->ComBuffer + Offset), Buffer, *NumBytes);

  Result = call_smm(mSmmStoreInfo->ApmCmd, SMMSTORE_CMD_RAW_WRITE, mArgComBufPhys);
  if (Result == SMMSTORE_RET_FAILURE) {
    return EFI_DEVICE_ERROR;
  } else if (Result == SMMSTORE_RET_UNSUPPORTED) {
    return EFI_UNSUPPORTED;
  } else if (Result != SMMSTORE_RET_SUCCESS) {
    return EFI_NO_RESPONSE;
  }

  return EFI_SUCCESS;
}


/**
  Erase a SMMStore block

  @param Lba    The logical block index to erase.

**/
EFI_STATUS
SMMStoreEraseBlock (
  IN   EFI_LBA                              Lba
  )
{
  UINTN             Result;

  if (!mSmmStoreInfo) {
    return EFI_NO_MEDIA;
  }
  if (Lba >= mSmmStoreInfo->NumBlocks) {
    return EFI_INVALID_PARAMETER;
  }

  mArgComBuf->raw_clear.block_id = Lba;

  Result = call_smm(mSmmStoreInfo->ApmCmd, SMMSTORE_CMD_RAW_CLEAR, mArgComBufPhys);
  if (Result == SMMSTORE_RET_FAILURE) {
    return EFI_DEVICE_ERROR;
  } else if (Result == SMMSTORE_RET_UNSUPPORTED) {
    return EFI_UNSUPPORTED;
  } else if (Result != SMMSTORE_RET_SUCCESS) {
    return EFI_NO_RESPONSE;
  }

  return EFI_SUCCESS;
}

VOID
EFIAPI
SMMStoreVirtualNotifyEvent (
  IN EFI_EVENT        Event,
  IN VOID             *Context
  )
{
  EfiConvertPointer (0x0, (VOID**)&mArgComBuf);
  if (mSmmStoreInfo) {
    EfiConvertPointer (0x0, (VOID**)&mSmmStoreInfo->ComBuffer);
    EfiConvertPointer (0x0, (VOID**)&mSmmStoreInfo);
  }

  return;
}

/**
  Initializes SMMStore support

  @param[in] Ptr                  A runtime buffer where arguments are stored
                                  for SMM communication
  @param[in] SmmStoreInfoHob      A runtime buffer with a copy of the
                                  SmmStore Info Hob

  @retval EFI_WRITE_PROTECTED   The SMMSTORE is not present.
  @retval EFI_SUCCESS           The SMMSTORE is supported.

**/
EFI_STATUS
SMMStoreInitialize (
    IN         VOID                      *Ptr,
    IN         SMMSTORE_INFO             *SmmStoreInfoHob
  )
{
  ASSERT (Ptr != NULL);
  ASSERT (SmmStoreInfoHob != NULL);

  mArgComBuf = Ptr;
  mArgComBufPhys = (UINT32)(UINTN)mArgComBuf;

  mSmmStoreInfo = SmmStoreInfoHob;

  return EFI_SUCCESS;
}