MdePkg/Library/PeiSmbusLib/SmbusLib.c

   1 /** @file
   2 Implementation of SmBusLib class library for PEI phase.
   3
   4 Copyright (c) 2006, Intel Corporation<BR>
   5 All rights reserved. This program and the accompanying materials
   6 are licensed and made available under the terms and conditions of the BSD License
   7 which accompanies this distribution.  The full text of the license may be found at
   8 http://opensource.org/licenses/bsd-license.php
   9
  10 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  11 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  12
  13
  14 Module Name: SmbusLib.c
  15
  16 **/
  17
  18 #include "InternalSmbusLib.h"
  19
  20 /**
  21   Executes an SMBUS quick read command.
  22
  23   Executes an SMBUS quick read command on the SMBUS device specified by SmBusAddress.
  24   Only the SMBUS slave address field of SmBusAddress is required.
  25   If Status is not NULL, then the status of the executed command is returned in Status.
  26   If PEC is set in SmBusAddress, then ASSERT().
  27   If Command in SmBusAddress is not zero, then ASSERT().
  28   If Length in SmBusAddress is not zero, then ASSERT().
  29   If any reserved bits of SmBusAddress are set, then ASSERT().
  30
  31   @param  SmBusAddress    Address that encodes the SMBUS Slave Address,
  32                           SMBUS Command, SMBUS Data Length, and PEC.
  33   @param  Status          Return status for the executed command.
  34                           This is an optional parameter and may be NULL.
  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_RESEARVED (SmBusAddress) == 0);
  48
  49   InternalSmBusExec (EfiSmbusQuickRead, SmBusAddress, 0, NULL, Status);
  50 }
  51
  52 /**
  53   Executes an SMBUS quick write command.
  54
  55   Executes an SMBUS quick write command on the SMBUS device specified by SmBusAddress.
  56   Only the SMBUS slave address field of SmBusAddress is required.
  57   If Status is not NULL, then the status of the executed command is returned in Status.
  58   If PEC is set in SmBusAddress, then ASSERT().
  59   If Command in SmBusAddress is not zero, then ASSERT().
  60   If Length in SmBusAddress is not zero, then ASSERT().
  61   If any reserved bits of SmBusAddress are set, then ASSERT().
  62
  63   @param  SmBusAddress    Address that encodes the SMBUS Slave Address,
  64                           SMBUS Command, SMBUS Data Length, and PEC.
  65   @param  Status          Return status for the executed command.
  66                           This is an optional parameter and may be NULL.
  67
  68 **/
  69 BOOLEAN
  70 EFIAPI
  71 SmBusQuickWrite (
  72   IN  UINTN                     SmBusAddress,
  73   OUT RETURN_STATUS             *Status       OPTIONAL
  74   )
  75 {
  76   ASSERT (!SMBUS_LIB_PEC (SmBusAddress));
  77   ASSERT (SMBUS_LIB_COMMAND (SmBusAddress)   == 0);
  78   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress)    == 0);
  79   ASSERT (SMBUS_LIB_RESEARVED (SmBusAddress) == 0);
  80
  81   InternalSmBusExec (EfiSmbusQuickWrite, SmBusAddress, 0, NULL, Status);
  82   //
  83   // Bugbug: Undefined return value in spec
  84   //
  85   return TRUE;
  86 }
  87
  88 /**
  89   Executes an SMBUS receive byte command.
  90
  91   Executes an SMBUS receive byte command on the SMBUS device specified by SmBusAddress.
  92   Only the SMBUS slave address field of SmBusAddress is required.
  93   The byte received from the SMBUS is returned.
  94   If Status is not NULL, then the status of the executed command is returned in Status.
  95   If Command in SmBusAddress is not zero, then ASSERT().
  96   If Length in SmBusAddress is not zero, then ASSERT().
  97   If any reserved bits of SmBusAddress are set, then ASSERT().
  98
  99   @param  SmBusAddress    Address that encodes the SMBUS Slave Address,
 100                           SMBUS Command, SMBUS Data Length, and PEC.
 101   @param  Status          Return status for the executed command.
 102                           This is an optional parameter and may be NULL.
 103
 104   @return The byte received from the SMBUS.
 105
 106 **/
 107 UINT8
 108 EFIAPI
 109 SmBusReceiveByte (
 110   IN  UINTN          SmBusAddress,
 111   OUT RETURN_STATUS  *Status        OPTIONAL
 112   )
 113 {
 114   UINT8   Byte;
 115
 116   ASSERT (SMBUS_LIB_COMMAND (SmBusAddress) == 0);
 117   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress)  == 0);
 118   ASSERT (SMBUS_LIB_RESEARVED (SmBusAddress) == 0);
 119
 120   InternalSmBusExec (EfiSmbusReceiveByte, SmBusAddress, 1, &Byte, Status);
 121
 122   return Byte;
 123 }
 124
 125 /**
 126   Executes an SMBUS send byte command.
 127
 128   Executes an SMBUS send byte command on the SMBUS device specified by SmBusAddress.
 129   The byte specified by Value is sent.
 130   Only the SMBUS slave address field of SmBusAddress is required.  Value is returned.
 131   If Status is not NULL, then the status of the executed command is returned in Status.
 132   If Command in SmBusAddress is not zero, then ASSERT().
 133   If Length in SmBusAddress is not zero, then ASSERT().
 134   If any reserved bits of SmBusAddress are set, then ASSERT().
 135
 136   @param  SmBusAddress    Address that encodes the SMBUS Slave Address,
 137                           SMBUS Command, SMBUS Data Length, and PEC.
 138   @param  Value           The 8-bit value to send.
 139   @param  Status          Return status for the executed command.
 140                           This is an optional parameter and may be NULL.
 141
 142   @return The parameter of Value.
 143
 144 **/
 145 UINT8
 146 EFIAPI
 147 SmBusSendByte (
 148   IN  UINTN          SmBusAddress,
 149   IN  UINT8          Value,
 150   OUT RETURN_STATUS  *Status        OPTIONAL
 151   )
 152 {
 153   UINT8   Byte;
 154
 155   ASSERT (SMBUS_LIB_COMMAND (SmBusAddress)   == 0);
 156   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress)    == 0);
 157   ASSERT (SMBUS_LIB_RESEARVED (SmBusAddress) == 0);
 158
 159   Byte   = Value;
 160   InternalSmBusExec (EfiSmbusSendByte, SmBusAddress, 1, &Byte, Status);
 161
 162   return Value;
 163 }
 164
 165 /**
 166   Executes an SMBUS read data byte command.
 167
 168   Executes an SMBUS read data byte command on the SMBUS device specified by SmBusAddress.
 169   Only the SMBUS slave address and SMBUS command fields of SmBusAddress are required.
 170   The 8-bit value read from the SMBUS is returned.
 171   If Status is not NULL, then the status of the executed command is returned in Status.
 172   If Length in SmBusAddress is not zero, then ASSERT().
 173   If any reserved bits of SmBusAddress are set, then ASSERT().
 174
 175   @param  SmBusAddress    Address that encodes the SMBUS Slave Address,
 176                           SMBUS Command, SMBUS Data Length, and PEC.
 177   @param  Status          Return status for the executed command.
 178                           This is an optional parameter and may be NULL.
 179
 180   @return The byte read from the SMBUS.
 181
 182 **/
 183 UINT8
 184 EFIAPI
 185 SmBusReadDataByte (
 186   IN  UINTN          SmBusAddress,
 187   OUT RETURN_STATUS  *Status        OPTIONAL
 188   )
 189 {
 190   UINT8   Byte;
 191
 192   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress)    == 0);
 193   ASSERT (SMBUS_LIB_RESEARVED (SmBusAddress) == 0);
 194
 195   InternalSmBusExec (EfiSmbusReadByte, SmBusAddress, 1, &Byte, Status);
 196
 197   return Byte;
 198 }
 199
 200 /**
 201   Executes an SMBUS write data byte command.
 202
 203   Executes an SMBUS write data byte command on the SMBUS device specified by SmBusAddress.
 204   The 8-bit value specified by Value is written.
 205   Only the SMBUS slave address and SMBUS command fields of SmBusAddress are required.
 206   Value is returned.
 207   If Status is not NULL, then the status of the executed command is returned in Status.
 208   If Length in SmBusAddress is not zero, then ASSERT().
 209   If any reserved bits of SmBusAddress are set, then ASSERT().
 210
 211   @param  SmBusAddress    Address that encodes the SMBUS Slave Address,
 212                           SMBUS Command, SMBUS Data Length, and PEC.
 213   @param  Value           The 8-bit value to write.
 214   @param  Status          Return status for the executed command.
 215                           This is an optional parameter and may be NULL.
 216
 217   @return The parameter of Value.
 218
 219 **/
 220 UINT8
 221 EFIAPI
 222 SmBusWriteDataByte (
 223   IN  UINTN          SmBusAddress,
 224   IN  UINT8          Value,
 225   OUT RETURN_STATUS  *Status        OPTIONAL
 226   )
 227 {
 228   UINT8   Byte;
 229
 230   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress)    == 0);
 231   ASSERT (SMBUS_LIB_RESEARVED (SmBusAddress) == 0);
 232
 233   Byte = Value;
 234   InternalSmBusExec (EfiSmbusWriteByte, SmBusAddress, 1, &Byte, Status);
 235
 236   return Value;
 237 }
 238
 239 /**
 240   Executes an SMBUS read data word command.
 241
 242   Executes an SMBUS read data word command on the SMBUS device specified by SmBusAddress.
 243   Only the SMBUS slave address and SMBUS command fields of SmBusAddress are required.
 244   The 16-bit value read from the SMBUS is returned.
 245   If Status is not NULL, then the status of the executed command is returned in Status.
 246   If Length in SmBusAddress is not zero, then ASSERT().
 247   If any reserved bits of SmBusAddress are set, then ASSERT().
 248
 249   @param  SmBusAddress    Address that encodes the SMBUS Slave Address,
 250                           SMBUS Command, SMBUS Data Length, and PEC.
 251   @param  Status          Return status for the executed command.
 252                           This is an optional parameter and may be NULL.
 253
 254   @return The byte read from the SMBUS.
 255
 256 **/
 257 UINT16
 258 EFIAPI
 259 SmBusReadDataWord (
 260   IN  UINTN          SmBusAddress,
 261   OUT RETURN_STATUS  *Status        OPTIONAL
 262   )
 263 {
 264   UINT16  Word;
 265
 266   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress)    == 0);
 267   ASSERT (SMBUS_LIB_RESEARVED (SmBusAddress) == 0);
 268
 269   InternalSmBusExec (EfiSmbusReadWord, SmBusAddress, 2, &Word, Status);
 270
 271   return Word;
 272 }
 273
 274 /**
 275   Executes an SMBUS write data word command.
 276
 277   Executes an SMBUS write data word command on the SMBUS device specified by SmBusAddress.
 278   The 16-bit value specified by Value is written.
 279   Only the SMBUS slave address and SMBUS command fields of SmBusAddress are required.
 280   Value is returned.
 281   If Status is not NULL, then the status of the executed command is returned in Status.
 282   If Length in SmBusAddress is not zero, then ASSERT().
 283   If any reserved bits of SmBusAddress are set, then ASSERT().
 284
 285   @param  SmBusAddress    Address that encodes the SMBUS Slave Address,
 286                           SMBUS Command, SMBUS Data Length, and PEC.
 287   @param  Value           The 16-bit value to write.
 288   @param  Status          Return status for the executed command.
 289                           This is an optional parameter and may be NULL.
 290
 291   @return The parameter of Value.
 292
 293 **/
 294 UINT16
 295 EFIAPI
 296 SmBusWriteDataWord (
 297   IN  UINTN          SmBusAddress,
 298   IN  UINT16         Value,
 299   OUT RETURN_STATUS  *Status        OPTIONAL
 300   )
 301 {
 302   UINT16  Word;
 303
 304   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress)    == 0);
 305   ASSERT (SMBUS_LIB_RESEARVED (SmBusAddress) == 0);
 306
 307   Word = Value;
 308   InternalSmBusExec (EfiSmbusWriteWord, SmBusAddress, 2, &Word, Status);
 309
 310   return Value;
 311 }
 312
 313 /**
 314   Executes an SMBUS process call command.
 315
 316   Executes an SMBUS process call command on the SMBUS device specified by SmBusAddress.
 317   The 16-bit value specified by Value is written.
 318   Only the SMBUS slave address and SMBUS command fields of SmBusAddress are required.
 319   The 16-bit value returned by the process call command is returned.
 320   If Status is not NULL, then the status of the executed command is returned in Status.
 321   If Length in SmBusAddress is not zero, then ASSERT().
 322   If any reserved bits of SmBusAddress are set, then ASSERT().
 323
 324   @param  SmBusAddress    Address that encodes the SMBUS Slave Address,
 325                           SMBUS Command, SMBUS Data Length, and PEC.
 326   @param  Value           The 16-bit value to write.
 327   @param  Status          Return status for the executed command.
 328                           This is an optional parameter and may be NULL.
 329
 330   @return The 16-bit value returned by the process call command.
 331
 332 **/
 333 UINT16
 334 EFIAPI
 335 SmBusProcessCall (
 336   IN  UINTN          SmBusAddress,
 337   IN  UINT16         Value,
 338   OUT RETURN_STATUS  *Status        OPTIONAL
 339   )
 340 {
 341   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress)    == 0);
 342   ASSERT (SMBUS_LIB_RESEARVED (SmBusAddress) == 0);
 343
 344   InternalSmBusExec (EfiSmbusProcessCall, SmBusAddress, 2, &Value, Status);
 345
 346   return Value;
 347 }
 348
 349 /**
 350   Executes an SMBUS read block command.
 351
 352   Executes an SMBUS read block command on the SMBUS device specified by SmBusAddress.
 353   Only the SMBUS slave address and SMBUS command fields of SmBusAddress are required.
 354   Bytes are read from the SMBUS and stored in Buffer.
 355   The number of bytes read is returned, and will never return a value larger than 32-bytes.
 356   If Status is not NULL, then the status of the executed command is returned in Status.
 357   It is the caller¡¯s responsibility to make sure Buffer is large enough for the total number of bytes read.
 358   SMBUS supports a maximum transfer size of 32 bytes, so Buffer does not need to be any larger than 32 bytes.
 359   If Length in SmBusAddress is not zero, then ASSERT().
 360   If Buffer is NULL, then ASSERT().
 361   If any reserved bits of SmBusAddress are set, then ASSERT().
 362
 363   @param  SmBusAddress    Address that encodes the SMBUS Slave Address,
 364                           SMBUS Command, SMBUS Data Length, and PEC.
 365   @param  Buffer          Pointer to the buffer to store the bytes read from the SMBUS.
 366   @param  Status          Return status for the executed command.
 367                           This is an optional parameter and may be NULL.
 368
 369   @return The number of bytes read.
 370
 371 **/
 372 UINTN
 373 EFIAPI
 374 SmBusReadBlock (
 375   IN  UINTN          SmBusAddress,
 376   OUT VOID           *Buffer,
 377   OUT RETURN_STATUS  *Status        OPTIONAL
 378   )
 379 {
 380   ASSERT (Buffer != NULL);
 381   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress)    == 0);
 382   ASSERT (SMBUS_LIB_RESEARVED (SmBusAddress) == 0);
 383
 384   return InternalSmBusExec (EfiSmbusReadBlock, SmBusAddress, 0x1f, Buffer, Status);
 385 }
 386
 387 /**
 388   Executes an SMBUS write block command.
 389
 390   Executes an SMBUS write block command on the SMBUS device specified by SmBusAddress.
 391   The SMBUS slave address, SMBUS command, and SMBUS length fields of SmBusAddress are required.
 392   Bytes are written to the SMBUS from Buffer.
 393   The number of bytes written is returned, and will never return a value larger than 32-bytes.
 394   If Status is not NULL, then the status of the executed command is returned in Status.
 395   If Length in SmBusAddress is zero or greater than 32, then ASSERT().
 396   If Buffer is NULL, then ASSERT().
 397   If any reserved bits of SmBusAddress are set, then ASSERT().
 398
 399   @param  SmBusAddress    Address that encodes the SMBUS Slave Address,
 400                           SMBUS Command, SMBUS Data Length, and PEC.
 401   @param  Buffer          Pointer to the buffer to store the bytes read from the SMBUS.
 402   @param  Status          Return status for the executed command.
 403                           This is an optional parameter and may be NULL.
 404
 405   @return The number of bytes written.
 406
 407 **/
 408 UINTN
 409 EFIAPI
 410 SmBusWriteBlock (
 411   IN  UINTN          SmBusAddress,
 412   OUT VOID           *Buffer,
 413   OUT RETURN_STATUS  *Status        OPTIONAL
 414   )
 415 {
 416   ASSERT (Buffer != NULL);
 417   ASSERT (SMBUS_LIB_RESEARVED (SmBusAddress) == 0);
 418
 419   return InternalSmBusExec (EfiSmbusWriteBlock, SmBusAddress, SMBUS_LIB_LENGTH (SmBusAddress), Buffer, Status);
 420 }
 421
 422 /**
 423   Executes an SMBUS block process call command.
 424
 425   Executes an SMBUS block process call command on the SMBUS device specified by SmBusAddress.
 426   The SMBUS slave address, SMBUS command, and SMBUS length fields of SmBusAddress are required.
 427   Bytes are written to the SMBUS from OutBuffer.  Bytes are then read from the SMBUS into InBuffer.
 428   If Status is not NULL, then the status of the executed command is returned in Status.
 429   It is the caller¡¯s responsibility to make sure InBuffer is large enough for the total number of bytes read.
 430   SMBUS supports a maximum transfer size of 32 bytes, so Buffer does not need to be any larger than 32 bytes.
 431   If OutBuffer is NULL, then ASSERT().
 432   If InBuffer is NULL, then ASSERT().
 433   If any reserved bits of SmBusAddress are set, then ASSERT().
 434
 435
 436   @param  SmBusAddress    Address that encodes the SMBUS Slave Address,
 437                           SMBUS Command, SMBUS Data Length, and PEC.
 438   @param  OutBuffer       Pointer to the buffer of bytes to write to the SMBUS.
 439   @param  InBuffer        Pointer to the buffer of bytes to read from the SMBUS.
 440   @param  Status          Return status for the executed command.
 441                           This is an optional parameter and may be NULL.
 442
 443   @return The number of bytes written.
 444
 445 **/
 446 UINTN
 447 EFIAPI
 448 SmBusBlockProcessCall (
 449   IN  UINTN          SmBusAddress,
 450   OUT VOID           *OutBuffer,
 451   OUT VOID           *InBuffer,
 452   OUT RETURN_STATUS  *Status        OPTIONAL
 453   )
 454 {
 455   ASSERT (InBuffer  != NULL);
 456   ASSERT (OutBuffer != NULL);
 457   ASSERT (SMBUS_LIB_RESEARVED (SmBusAddress) == 0);
 458
 459   //
 460   // BugBug: Not sure whether it's all right.
 461   //
 462   InternalSmBusExec (EfiSmbusWriteBlock, SmBusAddress, SMBUS_LIB_LENGTH (SmBusAddress), OutBuffer, Status);
 463
 464   return InternalSmBusExec (EfiSmbusReadBlock, SmBusAddress, 1, InBuffer, Status);
 465 }
 466
 467 /**
 468   Enumerates the SMBUS and assigns slave addresses.
 469
 470   Executes the SMBUS enumeration algorithm and assigns a valid address to all SMBUS slave devices.
 471   The total number of SMBUS slave devices detected is returned.
 472   The status of the executed command is returned.
 473   If Slave Address in SmBusAddress is not zero, then ASSERT().
 474   If Command in SmBusAddress is not zero, then ASSERT().
 475   If Length in SmBusAddress is not zero, then ASSERT().
 476   If PEC in SmBusAddress is set, then ASSERT().
 477   If any reserved bits of SmBusAddress are set, then ASSERT().
 478
 479   @param  SmBusAddress        Address that encodes the SMBUS Slave Address,
 480                               SMBUS Command, SMBUS Data Length, and PEC.
 481
 482   @retval RETURN_SUCCESS      The SMBUS command was executed.
 483   @retval RETURN_TIMEOUT      A timeout occurred while executing the SMBUS command.
 484   @retval RETURN_DEVICE_ERROR The request was not completed because a failure reflected
 485                               in the Host Status Register bit.
 486                               Device errors are a result of a transaction collision, illegal command field,
 487                               unclaimed cycle (host initiated), or bus errors (collisions).
 488
 489 **/
 490 RETURN_STATUS
 491 EFIAPI
 492 SmBusArpAll (
 493   IN UINTN  SmBusAddress
 494   )
 495 {
 496   ASSERT (!SMBUS_LIB_PEC (SmBusAddress));
 497   ASSERT (SMBUS_LIB_COMMAND (SmBusAddress)       == 0);
 498   ASSERT (SMBUS_LIB_RESEARVED (SmBusAddress)     == 0);
 499   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress)        == 0);
 500   ASSERT (SMBUS_LIB_SLAVE_ADDRESS (SmBusAddress) == 0);
 501
 502   return InternalSmBusArpDevice (SmBusAddress, NULL);
 503 }
 504
 505 /**
 506   Assigns an SMBUS slave addresses.
 507
 508   Assigns the SMBUS device specified by Uuid the slave address specified by SmBusAddress.
 509   The status of the executed command is returned.
 510   If Command in SmBusAddress is not zero, then ASSERT().
 511   If Length in SmBusAddress is not zero, then ASSERT().
 512   If PEC in SmBusAddress is set, then ASSERT().
 513   If any reserved bits of SmBusAddress are set, then ASSERT().
 514
 515   @param  SmBusAddress        Address that encodes the SMBUS Slave Address,
 516                               SMBUS Command, SMBUS Data Length, and PEC.
 517   @param  Uuid                Pointer to the UUID of the device to assign a slave address.
 518
 519   @retval RETURN_SUCCESS      The SMBUS command was executed.
 520   @retval RETURN_TIMEOUT      A timeout occurred while executing the SMBUS command.
 521   @retval RETURN_DEVICE_ERROR The request was not completed because a failure reflected
 522                               in the Host Status Register bit.
 523                               Device errors are a result of a transaction collision, illegal command field,
 524                               unclaimed cycle (host initiated), or bus errors (collisions).
 525
 526 **/
 527 RETURN_STATUS
 528 EFIAPI
 529 SmBusArpDevice (
 530   IN UINTN       SmBusAddress,
 531   IN CONST GUID  *Uuid
 532   )
 533 {
 534   ASSERT (!SMBUS_LIB_PEC (SmBusAddress));
 535   ASSERT (SMBUS_LIB_COMMAND (SmBusAddress)   == 0);
 536   ASSERT (SMBUS_LIB_RESEARVED (SmBusAddress) == 0);
 537   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress)    == 0);
 538
 539   return InternalSmBusArpDevice (SmBusAddress, Uuid);
 540 }
 541
 542 /**
 543   Retrieves the UUID associated with an SMBUS slave device.
 544
 545   Retrieves the UUID associated with the slave address specified
 546   by SmBusAddress and returns the UUID in Uuid.
 547   The status of the executed command is returned.
 548   If Command in SmBusAddress is not zero, then ASSERT().
 549   If Length in SmBusAddress is not zero, then ASSERT().
 550   If PEC in SmBusAddress is set, then ASSERT().
 551   If Uuid is NULL, then ASSERT().
 552   If any reserved bits of SmBusAddress are set, then ASSERT().
 553
 554   @param  SmBusAddress        Address that encodes the SMBUS Slave Address,
 555                               SMBUS Command, SMBUS Data Length, and PEC.
 556   @param  Uuid                Pointer to the UUID retrieved from the SMBUS slave device.
 557
 558   @retval RETURN_SUCCESS      The SMBUS command was executed.
 559   @retval RETURN_TIMEOUT      A timeout occurred while executing the SMBUS command.
 560   @retval RETURN_DEVICE_ERROR The request was not completed because a failure reflected
 561                               in the Host Status Register bit.
 562                               Device errors are a result of a transaction collision, illegal command field,
 563                               unclaimed cycle (host initiated), or bus errors (collisions).
 564
 565 **/
 566 RETURN_STATUS
 567 EFIAPI
 568 SmBusGetUuid (
 569   IN  UINTN  SmBusAddress,
 570   OUT GUID   *Uuid
 571   )
 572 {
 573   UINTN                     Length;
 574   EFI_SMBUS_DEVICE_MAP      *SmBusDeviceMap;
 575   RETURN_STATUS             ReturnStatus;
 576   UINTN                     SmbusDeviceAddress;
 577   UINTN                     Index;
 578
 579   ASSERT (Uuid != NULL);
 580   ASSERT (!SMBUS_LIB_PEC (SmBusAddress));
 581   ASSERT (SMBUS_LIB_COMMAND (SmBusAddress)   == 0);
 582   ASSERT (SMBUS_LIB_RESEARVED (SmBusAddress) == 0);
 583   ASSERT (SMBUS_LIB_LENGTH (SmBusAddress)    == 0);
 584
 585   ReturnStatus = InternalGetArpMap (&Length, &SmBusDeviceMap);
 586   if (!RETURN_ERROR (ReturnStatus)) {
 587     SmbusDeviceAddress = SMBUS_LIB_SLAVE_ADDRESS (SmBusAddress);
 588     for (Index = 0; Index < Length; Index++) {
 589       if (SmBusDeviceMap[Index].SmbusDeviceAddress.SmbusDeviceAddress == SmbusDeviceAddress) {
 590         CopyMem (Uuid, &SmBusDeviceMap[Index].SmbusDeviceUdid, sizeof (EFI_SMBUS_UDID));
 591         break;
 592       }
 593     }
 594   }
 595
 596   return ReturnStatus;
 597 }