MdePkg/Library/BaseSmbusLibNull/BaseSmbusLibNull.c

   1 /** @file
   2 Null implementation of SmBusLib class library.
   3
   4 Copyright (c) 2013 - 2018, Intel Corporation. All rights reserved.<BR>
   5 SPDX-License-Identifier: BSD-2-Clause-Patent
   6
   7 **/
   8
   9 #include <Base.h>
  10 #include <Library/SmbusLib.h>
  11 #include <Library/DebugLib.h>
  12
  13 /**
  14   Executes an SMBUS quick read command.
  15
  16   Executes an SMBUS quick read command on the SMBUS device specified by SmBusAddress.
  17   Only the SMBUS slave address field of SmBusAddress is required.
  18   If Status is not NULL, then the status of the executed command is returned in Status.
  19   If PEC is set in SmBusAddress, then ASSERT().
  20   If Command in SmBusAddress is not zero, then ASSERT().
  21   If Length in SmBusAddress is not zero, then ASSERT().
  22   If any reserved bits of SmBusAddress are set, then ASSERT().
  23
  24   @param  SmBusAddress  Address that encodes the SMBUS Slave Address,
  25                         SMBUS Command, SMBUS Data Length, and PEC.
  26   @param  Status        Return status for the executed command.
  27                         This is an optional parameter and may be NULL.
  28                         RETURN_SUCCESS  The SMBUS command was executed.
  29                         RETURN_TIMEOUT  A timeout occurred while executing the SMBUS command.
  30                         RETURN_DEVICE_ERROR The request was not completed because a failure
  31                         reflected in the Host Status Register bit.  Device errors are a result
  32                         of a transaction collision, illegal command field, unclaimed cycle
  33                         (host initiated), or bus errors (collisions).
  34                         RETURN_UNSUPPORTED  The SMBus operation is not supported.
  35
  36 **/
  37 VOID
  38 EFIAPI
  39 SmBusQuickRead (
  40   IN  UINTN          SmBusAddress,
  41   OUT RETURN_STATUS  *Status       OPTIONAL
  42   )
  43 {
  44   ASSERT (!SMBUS_LIB_PEC (SmBusAddress));
  45   ASSERT (SMBUS_LIB_COMMAND (SmBusAddress) == 0);
  46   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress) == 0);
  47   ASSERT (SMBUS_LIB_RESERVED (SmBusAddress) == 0);
  48   if (Status != NULL) {
  49     *Status = RETURN_UNSUPPORTED;
  50   }
  51 }
  52
  53 /**
  54   Executes an SMBUS quick write command.
  55
  56   Executes an SMBUS quick write command on the SMBUS device specified by SmBusAddress.
  57   Only the SMBUS slave address field of SmBusAddress is required.
  58   If Status is not NULL, then the status of the executed command is returned in Status.
  59   If PEC is set in SmBusAddress, then ASSERT().
  60   If Command in SmBusAddress is not zero, then ASSERT().
  61   If Length in SmBusAddress is not zero, then ASSERT().
  62   If any reserved bits of SmBusAddress are set, then ASSERT().
  63
  64   @param  SmBusAddress  Address that encodes the SMBUS Slave Address,
  65                         SMBUS Command, SMBUS Data Length, and PEC.
  66   @param  Status        Return status for the executed command.
  67                         This is an optional parameter and may be NULL.
  68                         RETURN_SUCCESS The SMBUS command was executed.
  69                         RETURN_TIMEOUT A timeout occurred while executing the SMBUS command.
  70                         RETURN_DEVICE_ERROR  The request was not completed because a failure
  71                         reflected in the Host Status Register bit.  Device errors are a result
  72                         of a transaction collision, illegal command field, unclaimed cycle
  73                         (host initiated), or bus errors (collisions).
  74                         RETURN_UNSUPPORTED  The SMBus operation is not supported.
  75
  76 **/
  77 VOID
  78 EFIAPI
  79 SmBusQuickWrite (
  80   IN  UINTN          SmBusAddress,
  81   OUT RETURN_STATUS  *Status       OPTIONAL
  82   )
  83 {
  84   ASSERT (!SMBUS_LIB_PEC (SmBusAddress));
  85   ASSERT (SMBUS_LIB_COMMAND (SmBusAddress) == 0);
  86   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress) == 0);
  87   ASSERT (SMBUS_LIB_RESERVED (SmBusAddress) == 0);
  88   if (Status != NULL) {
  89     *Status = RETURN_UNSUPPORTED;
  90   }
  91 }
  92
  93 /**
  94   Executes an SMBUS receive byte command.
  95
  96   Executes an SMBUS receive byte command on the SMBUS device specified by SmBusAddress.
  97   Only the SMBUS slave address field of SmBusAddress is required.
  98   The byte received from the SMBUS is returned.
  99   If Status is not NULL, then the status of the executed command is returned in Status.
 100   If Command in SmBusAddress is not zero, then ASSERT().
 101   If Length in SmBusAddress is not zero, then ASSERT().
 102   If any reserved bits of SmBusAddress are set, then ASSERT().
 103
 104   @param  SmBusAddress  Address that encodes the SMBUS Slave Address,
 105                         SMBUS Command, SMBUS Data Length, and PEC.
 106   @param  Status        Return status for the executed command.
 107                         This is an optional parameter and may be NULL.
 108                         RETURN_SUCCESS The SMBUS command was executed.
 109                         RETURN_TIMEOUT A timeout occurred while executing the SMBUS command.
 110                         RETURN_DEVICE_ERROR  The request was not completed because a failure
 111                         reflected in the Host Status Register bit.  Device errors are a result
 112                         of a transaction collision, illegal command field, unclaimed cycle
 113                         (host initiated), or bus errors (collisions).
 114                         RETURN_CRC_ERROR  The checksum is not correct (PEC is incorrect)
 115                         RETURN_UNSUPPORTED  The SMBus operation is not supported.
 116
 117   @return The byte received from the SMBUS.
 118
 119 **/
 120 UINT8
 121 EFIAPI
 122 SmBusReceiveByte (
 123   IN  UINTN          SmBusAddress,
 124   OUT RETURN_STATUS  *Status        OPTIONAL
 125   )
 126 {
 127   ASSERT (SMBUS_LIB_COMMAND (SmBusAddress) == 0);
 128   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress) == 0);
 129   ASSERT (SMBUS_LIB_RESERVED (SmBusAddress) == 0);
 130   if (Status != NULL) {
 131     *Status = RETURN_UNSUPPORTED;
 132   }
 133
 134   return 0;
 135 }
 136
 137 /**
 138   Executes an SMBUS send byte command.
 139
 140   Executes an SMBUS send byte command on the SMBUS device specified by SmBusAddress.
 141   The byte specified by Value is sent.
 142   Only the SMBUS slave address field of SmBusAddress is required.  Value is returned.
 143   If Status is not NULL, then the status of the executed command is returned in Status.
 144   If Command in SmBusAddress is not zero, then ASSERT().
 145   If Length in SmBusAddress is not zero, then ASSERT().
 146   If any reserved bits of SmBusAddress are set, then ASSERT().
 147
 148   @param  SmBusAddress  Address that encodes the SMBUS Slave Address,
 149                         SMBUS Command, SMBUS Data Length, and PEC.
 150   @param  Value         The 8-bit value to send.
 151   @param  Status        Return status for the executed command.
 152                         This is an optional parameter and may be NULL.
 153                         RETURN_SUCCESS The SMBUS command was executed.
 154                         RETURN_TIMEOUT A timeout occurred while executing the SMBUS command.
 155                         RETURN_DEVICE_ERROR  The request was not completed because a failure
 156                         reflected in the Host Status Register bit.  Device errors are a result
 157                         of a transaction collision, illegal command field, unclaimed cycle
 158                         (host initiated), or bus errors (collisions).
 159                         RETURN_CRC_ERROR  The checksum is not correct (PEC is incorrect)
 160                         RETURN_UNSUPPORTED  The SMBus operation is not supported.
 161
 162   @return The parameter of Value.
 163
 164 **/
 165 UINT8
 166 EFIAPI
 167 SmBusSendByte (
 168   IN  UINTN          SmBusAddress,
 169   IN  UINT8          Value,
 170   OUT RETURN_STATUS  *Status        OPTIONAL
 171   )
 172 {
 173   ASSERT (SMBUS_LIB_COMMAND (SmBusAddress) == 0);
 174   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress) == 0);
 175   ASSERT (SMBUS_LIB_RESERVED (SmBusAddress) == 0);
 176   if (Status != NULL) {
 177     *Status = RETURN_UNSUPPORTED;
 178   }
 179
 180   return 0;
 181 }
 182
 183 /**
 184   Executes an SMBUS read data byte command.
 185
 186   Executes an SMBUS read data byte command on the SMBUS device specified by SmBusAddress.
 187   Only the SMBUS slave address and SMBUS command fields of SmBusAddress are required.
 188   The 8-bit value read from the SMBUS is returned.
 189   If Status is not NULL, then the status of the executed command is returned in Status.
 190   If Length in SmBusAddress is not zero, then ASSERT().
 191   If any reserved bits of SmBusAddress are set, then ASSERT().
 192
 193   @param  SmBusAddress  Address that encodes the SMBUS Slave Address,
 194                         SMBUS Command, SMBUS Data Length, and PEC.
 195   @param  Status        Return status for the executed command.
 196                         This is an optional parameter and may be NULL.
 197                         RETURN_SUCCESS The SMBUS command was executed.
 198                         RETURN_TIMEOUT A timeout occurred while executing the SMBUS command.
 199                         RETURN_DEVICE_ERROR  The request was not completed because a failure
 200                         reflected in the Host Status Register bit.  Device errors are a result
 201                         of a transaction collision, illegal command field, unclaimed cycle
 202                         (host initiated), or bus errors (collisions).
 203                         RETURN_CRC_ERROR  The checksum is not correct (PEC is incorrect)
 204                         RETURN_UNSUPPORTED  The SMBus operation is not supported.
 205
 206   @return The byte read from the SMBUS.
 207
 208 **/
 209 UINT8
 210 EFIAPI
 211 SmBusReadDataByte (
 212   IN  UINTN          SmBusAddress,
 213   OUT RETURN_STATUS  *Status        OPTIONAL
 214   )
 215 {
 216   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress) == 0);
 217   ASSERT (SMBUS_LIB_RESERVED (SmBusAddress) == 0);
 218   if (Status != NULL) {
 219     *Status = RETURN_UNSUPPORTED;
 220   }
 221
 222   return 0;
 223 }
 224
 225 /**
 226   Executes an SMBUS write data byte command.
 227
 228   Executes an SMBUS write data byte command on the SMBUS device specified by SmBusAddress.
 229   The 8-bit value specified by Value is written.
 230   Only the SMBUS slave address and SMBUS command fields of SmBusAddress are required.
 231   Value is returned.
 232   If Status is not NULL, then the status of the executed command is returned in Status.
 233   If Length in SmBusAddress is not zero, then ASSERT().
 234   If any reserved bits of SmBusAddress are set, then ASSERT().
 235
 236   @param  SmBusAddress  Address that encodes the SMBUS Slave Address,
 237                         SMBUS Command, SMBUS Data Length, and PEC.
 238   @param  Value         The 8-bit value to write.
 239   @param  Status        Return status for the executed command.
 240                         This is an optional parameter and may be NULL.
 241                         RETURN_SUCCESS The SMBUS command was executed.
 242                         RETURN_TIMEOUT A timeout occurred while executing the SMBUS command.
 243                         RETURN_DEVICE_ERROR  The request was not completed because a failure
 244                         reflected in the Host Status Register bit.  Device errors are a result
 245                         of a transaction collision, illegal command field, unclaimed cycle
 246                         (host initiated), or bus errors (collisions).
 247                         RETURN_CRC_ERROR  The checksum is not correct (PEC is incorrect)
 248                         RETURN_UNSUPPORTED  The SMBus operation is not supported.
 249
 250   @return The parameter of Value.
 251
 252 **/
 253 UINT8
 254 EFIAPI
 255 SmBusWriteDataByte (
 256   IN  UINTN          SmBusAddress,
 257   IN  UINT8          Value,
 258   OUT RETURN_STATUS  *Status        OPTIONAL
 259   )
 260 {
 261   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress) == 0);
 262   ASSERT (SMBUS_LIB_RESERVED (SmBusAddress) == 0);
 263   if (Status != NULL) {
 264     *Status = RETURN_UNSUPPORTED;
 265   }
 266
 267   return 0;
 268 }
 269
 270 /**
 271   Executes an SMBUS read data word command.
 272
 273   Executes an SMBUS read data word command on the SMBUS device specified by SmBusAddress.
 274   Only the SMBUS slave address and SMBUS command fields of SmBusAddress are required.
 275   The 16-bit value read from the SMBUS is returned.
 276   If Status is not NULL, then the status of the executed command is returned in Status.
 277   If Length in SmBusAddress is not zero, then ASSERT().
 278   If any reserved bits of SmBusAddress are set, then ASSERT().
 279
 280   @param  SmBusAddress  Address that encodes the SMBUS Slave Address,
 281                         SMBUS Command, SMBUS Data Length, and PEC.
 282   @param  Status        Return status for the executed command.
 283                         This is an optional parameter and may be NULL.
 284                         RETURN_SUCCESS The SMBUS command was executed.
 285                         RETURN_TIMEOUT A timeout occurred while executing the SMBUS command.
 286                         RETURN_DEVICE_ERROR  The request was not completed because a failure
 287                         reflected in the Host Status Register bit.  Device errors are a result
 288                         of a transaction collision, illegal command field, unclaimed cycle
 289                         (host initiated), or bus errors (collisions).
 290                         RETURN_CRC_ERROR  The checksum is not correct (PEC is incorrect)
 291                         RETURN_UNSUPPORTED  The SMBus operation is not supported.
 292
 293   @return The byte read from the SMBUS.
 294
 295 **/
 296 UINT16
 297 EFIAPI
 298 SmBusReadDataWord (
 299   IN  UINTN          SmBusAddress,
 300   OUT RETURN_STATUS  *Status        OPTIONAL
 301   )
 302 {
 303   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress) == 0);
 304   ASSERT (SMBUS_LIB_RESERVED (SmBusAddress) == 0);
 305   if (Status != NULL) {
 306     *Status = RETURN_UNSUPPORTED;
 307   }
 308
 309   return 0;
 310 }
 311
 312 /**
 313   Executes an SMBUS write data word command.
 314
 315   Executes an SMBUS write data word command on the SMBUS device specified by SmBusAddress.
 316   The 16-bit value specified by Value is written.
 317   Only the SMBUS slave address and SMBUS command fields of SmBusAddress are required.
 318   Value is returned.
 319   If Status is not NULL, then the status of the executed command is returned in Status.
 320   If Length in SmBusAddress is not zero, then ASSERT().
 321   If any reserved bits of SmBusAddress are set, then ASSERT().
 322
 323   @param  SmBusAddress  Address that encodes the SMBUS Slave Address,
 324                         SMBUS Command, SMBUS Data Length, and PEC.
 325   @param  Value         The 16-bit value to write.
 326   @param  Status        Return status for the executed command.
 327                         This is an optional parameter and may be NULL.
 328                         RETURN_SUCCESS The SMBUS command was executed.
 329                         RETURN_TIMEOUT A timeout occurred while executing the SMBUS command.
 330                         RETURN_DEVICE_ERROR  The request was not completed because a failure
 331                         reflected in the Host Status Register bit.  Device errors are a result
 332                         of a transaction collision, illegal command field, unclaimed cycle
 333                         (host initiated), or bus errors (collisions).
 334                         RETURN_CRC_ERROR  The checksum is not correct (PEC is incorrect)
 335                         RETURN_UNSUPPORTED  The SMBus operation is not supported.
 336
 337   @return The parameter of Value.
 338
 339 **/
 340 UINT16
 341 EFIAPI
 342 SmBusWriteDataWord (
 343   IN  UINTN          SmBusAddress,
 344   IN  UINT16         Value,
 345   OUT RETURN_STATUS  *Status        OPTIONAL
 346   )
 347 {
 348   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress) == 0);
 349   ASSERT (SMBUS_LIB_RESERVED (SmBusAddress) == 0);
 350   if (Status != NULL) {
 351     *Status = RETURN_UNSUPPORTED;
 352   }
 353
 354   return 0;
 355 }
 356
 357 /**
 358   Executes an SMBUS process call command.
 359
 360   Executes an SMBUS process call command on the SMBUS device specified by SmBusAddress.
 361   The 16-bit value specified by Value is written.
 362   Only the SMBUS slave address and SMBUS command fields of SmBusAddress are required.
 363   The 16-bit value returned by the process call command is returned.
 364   If Status is not NULL, then the status of the executed command is returned in Status.
 365   If Length in SmBusAddress is not zero, then ASSERT().
 366   If any reserved bits of SmBusAddress are set, then ASSERT().
 367
 368   @param  SmBusAddress  Address that encodes the SMBUS Slave Address,
 369                         SMBUS Command, SMBUS Data Length, and PEC.
 370   @param  Value         The 16-bit value to write.
 371   @param  Status        Return status for the executed command.
 372                         This is an optional parameter and may be NULL.
 373                         RETURN_SUCCESS The SMBUS command was executed.
 374                         RETURN_TIMEOUT A timeout occurred while executing the SMBUS command.
 375                         RETURN_DEVICE_ERROR  The request was not completed because a failure
 376                         reflected in the Host Status Register bit.  Device errors are a result
 377                         of a transaction collision, illegal command field, unclaimed cycle
 378                         (host initiated), or bus errors (collisions).
 379                         RETURN_CRC_ERROR  The checksum is not correct (PEC is incorrect)
 380                         RETURN_UNSUPPORTED  The SMBus operation is not supported.
 381
 382   @return The 16-bit value returned by the process call command.
 383
 384 **/
 385 UINT16
 386 EFIAPI
 387 SmBusProcessCall (
 388   IN  UINTN          SmBusAddress,
 389   IN  UINT16         Value,
 390   OUT RETURN_STATUS  *Status        OPTIONAL
 391   )
 392 {
 393   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress) == 0);
 394   ASSERT (SMBUS_LIB_RESERVED (SmBusAddress) == 0);
 395   if (Status != NULL) {
 396     *Status = RETURN_UNSUPPORTED;
 397   }
 398
 399   return 0;
 400 }
 401
 402 /**
 403   Executes an SMBUS read block command.
 404
 405   Executes an SMBUS read block command on the SMBUS device specified by SmBusAddress.
 406   Only the SMBUS slave address and SMBUS command fields of SmBusAddress are required.
 407   Bytes are read from the SMBUS and stored in Buffer.
 408   The number of bytes read is returned, and will never return a value larger than 32-bytes.
 409   If Status is not NULL, then the status of the executed command is returned in Status.
 410   It is the caller's responsibility to make sure Buffer is large enough for the total number of bytes read.
 411   SMBUS supports a maximum transfer size of 32 bytes, so Buffer does not need to be any larger than 32 bytes.
 412   If Length in SmBusAddress is not zero, then ASSERT().
 413   If Buffer is NULL, then ASSERT().
 414   If any reserved bits of SmBusAddress are set, then ASSERT().
 415
 416   @param  SmBusAddress  Address that encodes the SMBUS Slave Address,
 417                         SMBUS Command, SMBUS Data Length, and PEC.
 418   @param  Buffer        Pointer to the buffer to store the bytes read from the SMBUS.
 419   @param  Status        Return status for the executed command.
 420                         This is an optional parameter and may be NULL.
 421                         RETURN_SUCCESS The SMBUS command was executed.
 422                         RETURN_TIMEOUT A timeout occurred while executing the SMBUS command.
 423                         RETURN_DEVICE_ERROR  The request was not completed because a failure
 424                         reflected in the Host Status Register bit.  Device errors are a result
 425                         of a transaction collision, illegal command field, unclaimed cycle
 426                         (host initiated), or bus errors (collisions).
 427                         RETURN_CRC_ERROR  The checksum is not correct (PEC is incorrect)
 428                         RETURN_UNSUPPORTED  The SMBus operation is not supported.
 429
 430   @return The number of bytes read.
 431
 432 **/
 433 UINTN
 434 EFIAPI
 435 SmBusReadBlock (
 436   IN  UINTN          SmBusAddress,
 437   OUT VOID           *Buffer,
 438   OUT RETURN_STATUS  *Status        OPTIONAL
 439   )
 440 {
 441   ASSERT (Buffer != NULL);
 442   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress) == 0);
 443   ASSERT (SMBUS_LIB_RESERVED (SmBusAddress) == 0);
 444   if (Status != NULL) {
 445     *Status = RETURN_UNSUPPORTED;
 446   }
 447
 448   return 0;
 449 }
 450
 451 /**
 452   Executes an SMBUS write block command.
 453
 454   Executes an SMBUS write block command on the SMBUS device specified by SmBusAddress.
 455   The SMBUS slave address, SMBUS command, and SMBUS length fields of SmBusAddress are required.
 456   Bytes are written to the SMBUS from Buffer.
 457   The number of bytes written is returned, and will never return a value larger than 32-bytes.
 458   If Status is not NULL, then the status of the executed command is returned in Status.
 459   If Length in SmBusAddress is zero or greater than 32, then ASSERT().
 460   If Buffer is NULL, then ASSERT().
 461   If any reserved bits of SmBusAddress are set, then ASSERT().
 462
 463   @param  SmBusAddress  Address that encodes the SMBUS Slave Address,
 464                         SMBUS Command, SMBUS Data Length, and PEC.
 465   @param  Buffer        Pointer to the buffer to store the bytes read from the SMBUS.
 466   @param  Status        Return status for the executed command.
 467                         This is an optional parameter and may be NULL.
 468                         RETURN_TIMEOUT A timeout occurred while executing the SMBUS command.
 469                         RETURN_DEVICE_ERROR  The request was not completed because a failure
 470                         reflected in the Host Status Register bit.  Device errors are a result
 471                         of a transaction collision, illegal command field, unclaimed cycle
 472                         (host initiated), or bus errors (collisions).
 473                         RETURN_CRC_ERROR  The checksum is not correct (PEC is incorrect)
 474                         RETURN_UNSUPPORTED  The SMBus operation is not supported.
 475
 476   @return The number of bytes written.
 477
 478 **/
 479 UINTN
 480 EFIAPI
 481 SmBusWriteBlock (
 482   IN  UINTN          SmBusAddress,
 483   OUT VOID           *Buffer,
 484   OUT RETURN_STATUS  *Status        OPTIONAL
 485   )
 486 {
 487   ASSERT (Buffer != NULL);
 488   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress) >= 1);
 489   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress) <= 32);
 490   ASSERT (SMBUS_LIB_RESERVED (SmBusAddress) == 0);
 491   if (Status != NULL) {
 492     *Status = RETURN_UNSUPPORTED;
 493   }
 494
 495   return 0;
 496 }
 497
 498 /**
 499   Executes an SMBUS block process call command.
 500
 501   Executes an SMBUS block process call command on the SMBUS device specified by SmBusAddress.
 502   The SMBUS slave address, SMBUS command, and SMBUS length fields of SmBusAddress are required.
 503   Bytes are written to the SMBUS from WriteBuffer.  Bytes are then read from the SMBUS into ReadBuffer.
 504   If Status is not NULL, then the status of the executed command is returned in Status.
 505   It is the caller's responsibility to make sure ReadBuffer is large enough for the total number of bytes read.
 506   SMBUS supports a maximum transfer size of 32 bytes, so Buffer does not need to be any larger than 32 bytes.
 507   If Length in SmBusAddress is zero or greater than 32, then ASSERT().
 508   If WriteBuffer is NULL, then ASSERT().
 509   If ReadBuffer is NULL, then ASSERT().
 510   If any reserved bits of SmBusAddress are set, then ASSERT().
 511
 512   @param  SmBusAddress  Address that encodes the SMBUS Slave Address,
 513                         SMBUS Command, SMBUS Data Length, and PEC.
 514   @param  WriteBuffer   Pointer to the buffer of bytes to write to the SMBUS.
 515   @param  ReadBuffer    Pointer to the buffer of bytes to read from the SMBUS.
 516   @param  Status        Return status for the executed command.
 517                         This is an optional parameter and may be NULL.
 518                         RETURN_TIMEOUT A timeout occurred while executing the SMBUS command.
 519                         RETURN_DEVICE_ERROR  The request was not completed because a failure
 520                         reflected in the Host Status Register bit.  Device errors are a result
 521                         of a transaction collision, illegal command field, unclaimed cycle
 522                         (host initiated), or bus errors (collisions).
 523                         RETURN_CRC_ERROR  The checksum is not correct (PEC is incorrect)
 524                         RETURN_UNSUPPORTED  The SMBus operation is not supported.
 525
 526   @return The number of bytes written.
 527
 528 **/
 529 UINTN
 530 EFIAPI
 531 SmBusBlockProcessCall (
 532   IN  UINTN          SmBusAddress,
 533   IN  VOID           *WriteBuffer,
 534   OUT VOID           *ReadBuffer,
 535   OUT RETURN_STATUS  *Status        OPTIONAL
 536   )
 537 {
 538   ASSERT (WriteBuffer != NULL);
 539   ASSERT (ReadBuffer  != NULL);
 540   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress) >= 1);
 541   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress) <= 32);
 542   ASSERT (SMBUS_LIB_RESERVED (SmBusAddress) == 0);
 543   if (Status != NULL) {
 544     *Status = RETURN_UNSUPPORTED;
 545   }
 546
 547   return 0;
 548 }