MdePkg/Library/PeiSmbusLibSmbus2Ppi/SmbusLib.c

   1 /** @file
   2 Implementation of SmBusLib class library for PEI phase.
   3
   4 Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>
   5 SPDX-License-Identifier: BSD-2-Clause-Patent
   6
   7
   8 **/
   9
  10 #include "InternalSmbusLib.h"
  11
  12 /**
  13   Executes an SMBUS quick read command.
  14
  15   Executes an SMBUS quick read command on the SMBUS device specified by SmBusAddress.
  16   Only the SMBUS slave address field of SmBusAddress is required.
  17   If Status is not NULL, then the status of the executed command is returned in Status.
  18   If PEC is set in SmBusAddress, then ASSERT().
  19   If Command in SmBusAddress is not zero, then ASSERT().
  20   If Length in SmBusAddress is not zero, then ASSERT().
  21   If any reserved bits of SmBusAddress are set, then ASSERT().
  22
  23   @param  SmBusAddress  The address that encodes the SMBUS Slave Address,
  24                         SMBUS Command, SMBUS Data Length, and PEC.
  25   @param  Status        Return status for the executed command.
  26                         This is an optional parameter and may be NULL.
  27                         RETURN_SUCCESS:  The SMBUS command was executed.
  28                         RETURN_TIMEOUT:  A timeout occurred while executing the
  29                         SMBUS command.
  30                         RETURN_DEVICE_ERROR: The request was not completed because
  31                         a failure reflected in the Host Status Register bit.
  32                         Device errors are a result of a transaction collision,
  33                         illegal command field, unclaimed cycle
  34                         (host initiated), or bus errors (collisions).
  35                         RETURN_UNSUPPORTED:  The SMBus operation is not supported.
  36
  37 **/
  38 VOID
  39 EFIAPI
  40 SmBusQuickRead (
  41   IN  UINTN                     SmBusAddress,
  42   OUT RETURN_STATUS             *Status       OPTIONAL
  43   )
  44 {
  45   ASSERT (!SMBUS_LIB_PEC (SmBusAddress));
  46   ASSERT (SMBUS_LIB_COMMAND (SmBusAddress)   == 0);
  47   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress)    == 0);
  48   ASSERT (SMBUS_LIB_RESERVED (SmBusAddress) == 0);
  49
  50   InternalSmBusExec (EfiSmbusQuickRead, SmBusAddress, 0, NULL, Status);
  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  The 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
  70                         SMBUS command.
  71                         RETURN_DEVICE_ERROR:  The request was not completed because
  72                         a failure reflected in the Host Status Register bit.  Device
  73                         errors are a result of a transaction collision, illegal
  74                         command field, unclaimed cycle (host initiated), or bus
  75                         errors (collisions).
  76                         RETURN_UNSUPPORTED::  The SMBus operation is not supported.
  77
  78 **/
  79 VOID
  80 EFIAPI
  81 SmBusQuickWrite (
  82   IN  UINTN                     SmBusAddress,
  83   OUT RETURN_STATUS             *Status       OPTIONAL
  84   )
  85 {
  86   ASSERT (!SMBUS_LIB_PEC (SmBusAddress));
  87   ASSERT (SMBUS_LIB_COMMAND (SmBusAddress)   == 0);
  88   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress)    == 0);
  89   ASSERT (SMBUS_LIB_RESERVED (SmBusAddress) == 0);
  90
  91   InternalSmBusExec (EfiSmbusQuickWrite, SmBusAddress, 0, NULL, Status);
  92 }
  93
  94 /**
  95   Executes an SMBUS receive byte command.
  96
  97   Executes an SMBUS receive byte command on the SMBUS device specified by SmBusAddress.
  98   Only the SMBUS slave address field of SmBusAddress is required.
  99   The byte received from the SMBUS is returned.
 100   If Status is not NULL, then the status of the executed command is returned in Status.
 101   If Command in SmBusAddress is not zero, then ASSERT().
 102   If Length in SmBusAddress is not zero, then ASSERT().
 103   If any reserved bits of SmBusAddress are set, then ASSERT().
 104
 105   @param  SmBusAddress  The address that encodes the SMBUS Slave Address,
 106                         SMBUS Command, SMBUS Data Length, and PEC.
 107   @param  Status        Return status for the executed command.
 108                         This is an optional parameter and may be NULL.
 109                         RETURN_SUCCESS: The SMBUS command was executed.
 110                         RETURN_TIMEOUT: A timeout occurred while executing the
 111                         SMBUS command.
 112                         RETURN_DEVICE_ERROR:  The request was not completed because
 113                         a failure reflected in the Host Status Register bit.
 114                         Device errors are a result of a transaction collision,
 115                         illegal command field, unclaimed cycle (host initiated),
 116                         or bus errors (collisions).
 117                         RETURN_CRC_ERROR:  The checksum is not correct. (PEC is incorrect.)
 118                         RETURN_UNSUPPORTED:  The SMBus operation is not supported.
 119
 120   @return The byte received from the SMBUS.
 121
 122 **/
 123 UINT8
 124 EFIAPI
 125 SmBusReceiveByte (
 126   IN  UINTN          SmBusAddress,
 127   OUT RETURN_STATUS  *Status        OPTIONAL
 128   )
 129 {
 130   UINT8   Byte;
 131
 132   ASSERT (SMBUS_LIB_COMMAND (SmBusAddress) == 0);
 133   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress)  == 0);
 134   ASSERT (SMBUS_LIB_RESERVED (SmBusAddress) == 0);
 135
 136   InternalSmBusExec (EfiSmbusReceiveByte, SmBusAddress, 1, &Byte, Status);
 137
 138   return Byte;
 139 }
 140
 141 /**
 142   Executes an SMBUS send byte command.
 143
 144   Executes an SMBUS send byte command on the SMBUS device specified by SmBusAddress.
 145   The byte specified by Value is sent.
 146   Only the SMBUS slave address field of SmBusAddress is required.  Value is returned.
 147   If Status is not NULL, then the status of the executed command is returned in Status.
 148   If Command in SmBusAddress is not zero, then ASSERT().
 149   If Length in SmBusAddress is not zero, then ASSERT().
 150   If any reserved bits of SmBusAddress are set, then ASSERT().
 151
 152   @param  SmBusAddress  The address that encodes the SMBUS Slave Address,
 153                         SMBUS Command, SMBUS Data Length, and PEC.
 154   @param  Value         The 8-bit value to send.
 155   @param  Status        Return status for the executed command.
 156                         This is an optional parameter and may be NULL.
 157                         RETURN_SUCCESS: The SMBUS command was executed.
 158                         RETURN_TIMEOUT: A timeout occurred while executing the
 159                         SMBUS command.
 160                         RETURN_DEVICE_ERROR:  The request was not completed because
 161                         a failure reflected in the Host Status Register bit.  Device
 162                         errors are a result of a transaction collision, illegal
 163                         command field, unclaimed cycle (host initiated), or bus
 164                         errors (collisions).
 165                         RETURN_CRC_ERROR:  The checksum is not correct. (PEC is incorrect.)
 166                         RETURN_UNSUPPORTED:  The SMBus operation is not supported.
 167
 168   @return The parameter of Value.
 169
 170 **/
 171 UINT8
 172 EFIAPI
 173 SmBusSendByte (
 174   IN  UINTN          SmBusAddress,
 175   IN  UINT8          Value,
 176   OUT RETURN_STATUS  *Status        OPTIONAL
 177   )
 178 {
 179   UINT8   Byte;
 180
 181   ASSERT (SMBUS_LIB_COMMAND (SmBusAddress)   == 0);
 182   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress)    == 0);
 183   ASSERT (SMBUS_LIB_RESERVED (SmBusAddress) == 0);
 184
 185   Byte   = Value;
 186   InternalSmBusExec (EfiSmbusSendByte, SmBusAddress, 1, &Byte, Status);
 187
 188   return Value;
 189 }
 190
 191 /**
 192   Executes an SMBUS read data byte command.
 193
 194   Executes an SMBUS read data byte command on the SMBUS device specified by SmBusAddress.
 195   Only the SMBUS slave address and SMBUS command fields of SmBusAddress are required.
 196   The 8-bit value read from the SMBUS is returned.
 197   If Status is not NULL, then the status of the executed command is returned in Status.
 198   If Length in SmBusAddress is not zero, then ASSERT().
 199   If any reserved bits of SmBusAddress are set, then ASSERT().
 200
 201   @param  SmBusAddress    The address that encodes the SMBUS Slave Address,
 202                           SMBUS Command, SMBUS Data Length, and PEC.
 203   @param  Status        Return status for the executed command.
 204                         This is an optional parameter and may be NULL.
 205                         RETURN_SUCCESS: The SMBUS command was executed.
 206                         RETURN_TIMEOUT: A timeout occurred while executing the
 207                         SMBUS command.
 208                         RETURN_DEVICE_ERROR:  The request was not completed because
 209                         a failure reflected in the Host Status Register bit.
 210                         Device errors are a result of a transaction collision,
 211                         illegal command field, unclaimed cycle (host initiated),
 212                        or bus errors (collisions).
 213                         RETURN_CRC_ERROR:  The checksum is not correct. (PEC is incorrect.)
 214                         RETURN_UNSUPPORTED:  The SMBus operation is not supported.
 215
 216   @return The byte read from the SMBUS.
 217
 218 **/
 219 UINT8
 220 EFIAPI
 221 SmBusReadDataByte (
 222   IN  UINTN          SmBusAddress,
 223   OUT RETURN_STATUS  *Status        OPTIONAL
 224   )
 225 {
 226   UINT8   Byte;
 227
 228   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress)    == 0);
 229   ASSERT (SMBUS_LIB_RESERVED (SmBusAddress) == 0);
 230
 231   InternalSmBusExec (EfiSmbusReadByte, SmBusAddress, 1, &Byte, Status);
 232
 233   return Byte;
 234 }
 235
 236 /**
 237   Executes an SMBUS write data byte command.
 238
 239   Executes an SMBUS write data byte command on the SMBUS device specified by SmBusAddress.
 240   The 8-bit value specified by Value is written.
 241   Only the SMBUS slave address and SMBUS command fields of SmBusAddress are required.
 242   Value is returned.
 243   If Status is not NULL, then the status of the executed command is returned in Status.
 244   If Length in SmBusAddress is not zero, then ASSERT().
 245   If any reserved bits of SmBusAddress are set, then ASSERT().
 246
 247   @param  SmBusAddress  The address that encodes the SMBUS Slave Address,
 248                         SMBUS Command, SMBUS Data Length, and PEC.
 249   @param  Value         The 8-bit value to write.
 250   @param  Status        Return status for the executed command.
 251                         This is an optional parameter and may be NULL.
 252                         RETURN_SUCCESS: The SMBUS command was executed.
 253                         RETURN_TIMEOUT: A timeout occurred while executing the
 254                         SMBUS command.
 255                         RETURN_DEVICE_ERROR:  The request was not completed because
 256                         a failure reflected in the Host Status Register bit.
 257                         Device errors are a result of a transaction collision,
 258                         illegal command field, unclaimed cycle (host initiated),
 259                         or bus errors (collisions).
 260                         RETURN_CRC_ERROR:  The checksum is not correct. (PEC is incorrect.)
 261                         RETURN_UNSUPPORTED:  The SMBus operation is not supported.
 262
 263   @return The parameter of Value.
 264
 265 **/
 266 UINT8
 267 EFIAPI
 268 SmBusWriteDataByte (
 269   IN  UINTN          SmBusAddress,
 270   IN  UINT8          Value,
 271   OUT RETURN_STATUS  *Status        OPTIONAL
 272   )
 273 {
 274   UINT8   Byte;
 275
 276   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress)    == 0);
 277   ASSERT (SMBUS_LIB_RESERVED (SmBusAddress) == 0);
 278
 279   Byte = Value;
 280   InternalSmBusExec (EfiSmbusWriteByte, SmBusAddress, 1, &Byte, Status);
 281
 282   return Value;
 283 }
 284
 285 /**
 286   Executes an SMBUS read data word command.
 287
 288   Executes an SMBUS read data word command on the SMBUS device specified by SmBusAddress.
 289   Only the SMBUS slave address and SMBUS command fields of SmBusAddress are required.
 290   The 16-bit value read from the SMBUS is returned.
 291   If Status is not NULL, then the status of the executed command is returned in Status.
 292   If Length in SmBusAddress is not zero, then ASSERT().
 293   If any reserved bits of SmBusAddress are set, then ASSERT().
 294
 295   @param  SmBusAddress  The address that encodes the SMBUS Slave Address,
 296                         SMBUS Command, SMBUS Data Length, and PEC.
 297   @param  Status        Return status for the executed command.
 298                         This is an optional parameter and may be NULL.
 299                         RETURN_SUCCESS: The SMBUS command was executed.
 300                         RETURN_TIMEOUT: A timeout occurred while executing the
 301                         SMBUS command.
 302                         RETURN_DEVICE_ERROR:  The request was not completed because
 303                         a failure reflected in the Host Status Register bit.
 304                         Device errors are a result of a transaction collision,
 305                         illegal command field, unclaimed cycle (host initiated),
 306                         or bus errors (collisions).
 307                         RETURN_CRC_ERROR:  The checksum is not correct. (PEC is incorrect.)
 308                         RETURN_UNSUPPORTED:  The SMBus operation is not supported.
 309
 310   @return The byte read from the SMBUS.
 311
 312 **/
 313 UINT16
 314 EFIAPI
 315 SmBusReadDataWord (
 316   IN  UINTN          SmBusAddress,
 317   OUT RETURN_STATUS  *Status        OPTIONAL
 318   )
 319 {
 320   UINT16  Word;
 321
 322   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress)    == 0);
 323   ASSERT (SMBUS_LIB_RESERVED (SmBusAddress) == 0);
 324
 325   InternalSmBusExec (EfiSmbusReadWord, SmBusAddress, 2, &Word, Status);
 326
 327   return Word;
 328 }
 329
 330 /**
 331   Executes an SMBUS write data word command.
 332
 333   Executes an SMBUS write data word command on the SMBUS device specified by SmBusAddress.
 334   The 16-bit value specified by Value is written.
 335   Only the SMBUS slave address and SMBUS command fields of SmBusAddress are required.
 336   Value is returned.
 337   If Status is not NULL, then the status of the executed command is returned in Status.
 338   If Length in SmBusAddress is not zero, then ASSERT().
 339   If any reserved bits of SmBusAddress are set, then ASSERT().
 340
 341   @param  SmBusAddress  The address that encodes the SMBUS Slave Address,
 342                         SMBUS Command, SMBUS Data Length, and PEC.
 343   @param  Value         The 16-bit value to write.
 344   @param  Status        Return status for the executed command.
 345                         This is an optional parameter and may be NULL.
 346                         RETURN_SUCCESS: The SMBUS command was executed.
 347                         RETURN_TIMEOUT: A timeout occurred while executing the
 348                         SMBUS command.
 349                         RETURN_DEVICE_ERROR:  The request was not completed because
 350                         a failure reflected in the Host Status Register bit.
 351                         Device errors are a result of a transaction collision,
 352                         illegal command field, unclaimed cycle (host initiated),
 353                         or bus errors (collisions).
 354                         RETURN_CRC_ERROR:  The checksum is not correct. (PEC is incorrect.)
 355                         RETURN_UNSUPPORTED:  The SMBus operation is not supported.
 356
 357   @return The parameter of Value.
 358
 359 **/
 360 UINT16
 361 EFIAPI
 362 SmBusWriteDataWord (
 363   IN  UINTN          SmBusAddress,
 364   IN  UINT16         Value,
 365   OUT RETURN_STATUS  *Status        OPTIONAL
 366   )
 367 {
 368   UINT16  Word;
 369
 370   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress)    == 0);
 371   ASSERT (SMBUS_LIB_RESERVED (SmBusAddress) == 0);
 372
 373   Word = Value;
 374   InternalSmBusExec (EfiSmbusWriteWord, SmBusAddress, 2, &Word, Status);
 375
 376   return Value;
 377 }
 378
 379 /**
 380   Executes an SMBUS process call command.
 381
 382   Executes an SMBUS process call command on the SMBUS device specified by SmBusAddress.
 383   The 16-bit value specified by Value is written.
 384   Only the SMBUS slave address and SMBUS command fields of SmBusAddress are required.
 385   The 16-bit value returned by the process call command is returned.
 386   If Status is not NULL, then the status of the executed command is returned in Status.
 387   If Length in SmBusAddress is not zero, then ASSERT().
 388   If any reserved bits of SmBusAddress are set, then ASSERT().
 389
 390   @param  SmBusAddress  The address that encodes the SMBUS Slave Address,
 391                         SMBUS Command, SMBUS Data Length, and PEC.
 392   @param  Value         The 16-bit value to write.
 393   @param  Status        Return status for the executed command.
 394                         This is an optional parameter and may be NULL.
 395                         RETURN_SUCCESS: The SMBUS command was executed.
 396                         RETURN_TIMEOUT: A timeout occurred while executing the
 397                         SMBUS command.
 398                         RETURN_DEVICE_ERROR:  The request was not completed because
 399                         a failure reflected in the Host Status Register bit.
 400                         Device errors are a result of a transaction collision,
 401                         illegal command field, unclaimed cycle (host initiated),
 402                         or bus errors (collisions).
 403                         RETURN_CRC_ERROR:  The checksum is not correct. (PEC is incorrect.)
 404                         RETURN_UNSUPPORTED:  The SMBus operation is not supported.
 405
 406   @return The 16-bit value returned by the process call command.
 407
 408 **/
 409 UINT16
 410 EFIAPI
 411 SmBusProcessCall (
 412   IN  UINTN          SmBusAddress,
 413   IN  UINT16         Value,
 414   OUT RETURN_STATUS  *Status        OPTIONAL
 415   )
 416 {
 417   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress)    == 0);
 418   ASSERT (SMBUS_LIB_RESERVED (SmBusAddress) == 0);
 419
 420   InternalSmBusExec (EfiSmbusProcessCall, SmBusAddress, 2, &Value, Status);
 421
 422   return Value;
 423 }
 424
 425 /**
 426   Executes an SMBUS read block command.
 427
 428   Executes an SMBUS read block command on the SMBUS device specified by SmBusAddress.
 429   Only the SMBUS slave address and SMBUS command fields of SmBusAddress are required.
 430   Bytes are read from the SMBUS and stored in Buffer.
 431   The number of bytes read is returned, and will never return a value larger than 32-bytes.
 432   If Status is not NULL, then the status of the executed command is returned in Status.
 433   It is the caller's responsibility to make sure Buffer is large enough for the total number of bytes read.
 434   SMBUS supports a maximum transfer size of 32 bytes, so Buffer does not need to be any larger than 32 bytes.
 435   If Length in SmBusAddress is not zero, then ASSERT().
 436   If Buffer is NULL, then ASSERT().
 437   If any reserved bits of SmBusAddress are set, then ASSERT().
 438
 439   @param  SmBusAddress  The address that encodes the SMBUS Slave Address,
 440                         SMBUS Command, SMBUS Data Length, and PEC.
 441   @param  Buffer        The pointer to the buffer to store the bytes read from the SMBUS.
 442   @param  Status        Return status for the executed command.
 443                         This is an optional parameter and may be NULL.
 444                         RETURN_SUCCESS: The SMBUS command was executed.
 445                         RETURN_TIMEOUT: A timeout occurred while executing the
 446                         SMBUS command.
 447                         RETURN_DEVICE_ERROR:  The request was not completed because
 448                         a failure reflected in the Host Status Register bit.
 449                         Device errors are a result of a transaction collision,
 450                         illegal command field, unclaimed cycle (host initiated),
 451                         or bus errors (collisions).
 452                         RETURN_CRC_ERROR:  The checksum is not correct. (PEC is incorrect.)
 453                         RETURN_UNSUPPORTED:  The SMBus operation is not supported.
 454
 455   @return The number of bytes read.
 456
 457 **/
 458 UINTN
 459 EFIAPI
 460 SmBusReadBlock (
 461   IN  UINTN          SmBusAddress,
 462   OUT VOID           *Buffer,
 463   OUT RETURN_STATUS  *Status        OPTIONAL
 464   )
 465 {
 466   ASSERT (Buffer != NULL);
 467   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress)    == 0);
 468   ASSERT (SMBUS_LIB_RESERVED (SmBusAddress) == 0);
 469
 470   return InternalSmBusExec (EfiSmbusReadBlock, SmBusAddress, 0x20, Buffer, Status);
 471 }
 472
 473 /**
 474   Executes an SMBUS write block command.
 475
 476   Executes an SMBUS write block command on the SMBUS device specified by SmBusAddress.
 477   The SMBUS slave address, SMBUS command, and SMBUS length fields of SmBusAddress are required.
 478   Bytes are written to the SMBUS from Buffer.
 479   The number of bytes written is returned, and will never return a value larger than 32-bytes.
 480   If Status is not NULL, then the status of the executed command is returned in Status.
 481   If Length in SmBusAddress is zero or greater than 32, then ASSERT().
 482   If Buffer is NULL, then ASSERT().
 483   If any reserved bits of SmBusAddress are set, then ASSERT().
 484
 485   @param  SmBusAddress  The address that encodes the SMBUS Slave Address,
 486                         MBUS Command, SMBUS Data Length, and PEC.
 487   @param  Buffer        The pointer to the buffer to store the bytes read from the SMBUS.
 488   @param  Status        Return status for the executed command.
 489                         This is an optional parameter and may be NULL.
 490                         RETURN_TIMEOUT: A timeout occurred while executing the
 491                         SMBUS command.
 492                         RETURN_DEVICE_ERROR:  The request was not completed because
 493                         a failure reflected in the Host Status Register bit.
 494                         Device errors are a result of a transaction collision,
 495                         illegal command field, unclaimed cycle (host initiated),
 496                         or bus errors (collisions).
 497                         RETURN_CRC_ERROR:  The checksum is not correct (PEC is incorrect)
 498                         RETURN_UNSUPPORTED:  The SMBus operation is not supported.
 499
 500   @return The number of bytes written.
 501
 502 **/
 503 UINTN
 504 EFIAPI
 505 SmBusWriteBlock (
 506   IN  UINTN          SmBusAddress,
 507   OUT VOID           *Buffer,
 508   OUT RETURN_STATUS  *Status        OPTIONAL
 509   )
 510 {
 511   UINTN  Length;
 512
 513   ASSERT (Buffer != NULL);
 514   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress) >= 1);
 515   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress) <= 32);
 516   ASSERT (SMBUS_LIB_RESERVED (SmBusAddress) == 0);
 517
 518   Length = SMBUS_LIB_LENGTH (SmBusAddress);
 519   return InternalSmBusExec (EfiSmbusWriteBlock, SmBusAddress, Length, Buffer, Status);
 520 }
 521
 522 /**
 523   Executes an SMBUS block process call command.
 524
 525   Executes an SMBUS block process call command on the SMBUS device specified by SmBusAddress.
 526   The SMBUS slave address, SMBUS command, and SMBUS length fields of SmBusAddress are required.
 527   Bytes are written to the SMBUS from WriteBuffer.  Bytes are then read from the SMBUS into ReadBuffer.
 528   If Status is not NULL, then the status of the executed command is returned in Status.
 529   It is the caller's responsibility to make sure ReadBuffer is large enough for the total number of bytes read.
 530   SMBUS supports a maximum transfer size of 32 bytes, so Buffer does not need to be any larger than 32 bytes.
 531   If Length in SmBusAddress is zero or greater than 32, then ASSERT().
 532   If WriteBuffer is NULL, then ASSERT().
 533   If ReadBuffer is NULL, then ASSERT().
 534   If any reserved bits of SmBusAddress are set, then ASSERT().
 535
 536   @param  SmBusAddress  The address that encodes the SMBUS Slave Address,
 537                         SMBUS Command, SMBUS Data Length, and PEC.
 538   @param  WriteBuffer   The pointer to the buffer of bytes to write to the SMBUS.
 539   @param  ReadBuffer    The pointer to the buffer of bytes to read from the SMBUS.
 540   @param  Status        Return status for the executed command.
 541                         This is an optional parameter and may be NULL.
 542                         RETURN_TIMEOUT: A timeout occurred while executing the
 543                         SMBUS command.
 544                         RETURN_DEVICE_ERROR:  The request was not completed because
 545                         a failure reflected in the Host Status Register bit.
 546                         Device errors are a result of a transaction collision,
 547                         illegal command field, unclaimed cycle (host initiated),
 548                         or bus errors (collisions).
 549                         RETURN_CRC_ERROR  The checksum is not correct. (PEC is incorrect.)
 550                         RETURN_UNSUPPORTED:  The SMBus operation is not supported.
 551
 552   @return The number of bytes written.
 553
 554 **/
 555 UINTN
 556 EFIAPI
 557 SmBusBlockProcessCall (
 558   IN  UINTN          SmBusAddress,
 559   IN  VOID           *WriteBuffer,
 560   OUT VOID           *ReadBuffer,
 561   OUT RETURN_STATUS  *Status        OPTIONAL
 562   )
 563 {
 564   UINTN   Length;
 565
 566   ASSERT (WriteBuffer != NULL);
 567   ASSERT (ReadBuffer  != NULL);
 568   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress) >= 1);
 569   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress) <= 32);
 570   ASSERT (SMBUS_LIB_RESERVED (SmBusAddress) == 0);
 571
 572   Length = SMBUS_LIB_LENGTH (SmBusAddress);
 573   //
 574   // Assuming that ReadBuffer is large enough to save another memory copy.
 575   //
 576   ReadBuffer = CopyMem (ReadBuffer, WriteBuffer, Length);
 577   return InternalSmBusExec (EfiSmbusBWBRProcessCall, SmBusAddress, Length, ReadBuffer, Status);
 578 }