MdeModulePkg/Bus/I2c/I2cDxe/I2cHost.c

   1 /** @file
   2   This file implements I2C Host Protocol which provides callers with the ability to
   3   do I/O transactions to all of the devices on the I2C bus.
   4
   5   Copyright (c) 2014, Hewlett-Packard Development Company, L.P.<BR>
   6   Copyright (c) 2013 - 2018, Intel Corporation. All rights reserved.<BR>
   7   This program and the accompanying materials
   8   are licensed and made available under the terms and conditions of the BSD License
   9   which accompanies this distribution.  The full text of the license may be found at
  10   http://opensource.org/licenses/bsd-license.php
  11
  12   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  13   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  14
  15 **/
  16
  17 #include "I2cDxe.h"
  18
  19 EFI_DRIVER_BINDING_PROTOCOL gI2cHostDriverBinding = {
  20   I2cHostDriverSupported,
  21   I2cHostDriverStart,
  22   I2cHostDriverStop,
  23   0x10,
  24   NULL,
  25   NULL
  26 };
  27
  28 //
  29 // Driver name table
  30 //
  31 GLOBAL_REMOVE_IF_UNREFERENCED EFI_UNICODE_STRING_TABLE mI2cHostDriverNameTable[] = {
  32   { "eng;en", L"I2c Host Driver" },
  33   { NULL , NULL }
  34 };
  35
  36 //
  37 // EFI Component Name Protocol
  38 //
  39 GLOBAL_REMOVE_IF_UNREFERENCED EFI_COMPONENT_NAME_PROTOCOL  gI2cHostComponentName = {
  40   (EFI_COMPONENT_NAME_GET_DRIVER_NAME) I2cHostComponentNameGetDriverName,
  41   (EFI_COMPONENT_NAME_GET_CONTROLLER_NAME) I2cHostComponentNameGetControllerName,
  42   "eng"
  43 };
  44
  45 //
  46 // EFI Component Name 2 Protocol
  47 //
  48 GLOBAL_REMOVE_IF_UNREFERENCED EFI_COMPONENT_NAME2_PROTOCOL gI2cHostComponentName2 = {
  49   I2cHostComponentNameGetDriverName,
  50   I2cHostComponentNameGetControllerName,
  51   "en"
  52 };
  53
  54 /**
  55   Retrieves a Unicode string that is the user readable name of the driver.
  56
  57   This function retrieves the user readable name of a driver in the form of a
  58   Unicode string. If the driver specified by This has a user readable name in
  59   the language specified by Language, then a pointer to the driver name is
  60   returned in DriverName, and EFI_SUCCESS is returned. If the driver specified
  61   by This does not support the language specified by Language,
  62   then EFI_UNSUPPORTED is returned.
  63
  64   @param  This[in]              A pointer to the EFI_COMPONENT_NAME2_PROTOCOL or
  65                                 EFI_COMPONENT_NAME_PROTOCOL instance.
  66
  67   @param  Language[in]          A pointer to a Null-terminated ASCII string
  68                                 array indicating the language. This is the
  69                                 language of the driver name that the caller is
  70                                 requesting, and it must match one of the
  71                                 languages specified in SupportedLanguages. The
  72                                 number of languages supported by a driver is up
  73                                 to the driver writer. Language is specified
  74                                 in RFC 4646 or ISO 639-2 language code format.
  75
  76   @param  DriverName[out]       A pointer to the Unicode string to return.
  77                                 This Unicode string is the name of the
  78                                 driver specified by This in the language
  79                                 specified by Language.
  80
  81   @retval EFI_SUCCESS           The Unicode string for the Driver specified by
  82                                 This and the language specified by Language was
  83                                 returned in DriverName.
  84
  85   @retval EFI_INVALID_PARAMETER Language is NULL.
  86
  87   @retval EFI_INVALID_PARAMETER DriverName is NULL.
  88
  89   @retval EFI_UNSUPPORTED       The driver specified by This does not support
  90                                 the language specified by Language.
  91
  92 **/
  93 EFI_STATUS
  94 EFIAPI
  95 I2cHostComponentNameGetDriverName (
  96   IN  EFI_COMPONENT_NAME2_PROTOCOL  *This,
  97   IN  CHAR8                        *Language,
  98   OUT CHAR16                       **DriverName
  99   )
 100 {
 101   return LookupUnicodeString2 (
 102            Language,
 103            This->SupportedLanguages,
 104            mI2cHostDriverNameTable,
 105            DriverName,
 106            (BOOLEAN)(This != &gI2cHostComponentName2)
 107            );
 108 }
 109
 110 /**
 111   Retrieves a Unicode string that is the user readable name of the controller
 112   that is being managed by a driver.
 113
 114   This function retrieves the user readable name of the controller specified by
 115   ControllerHandle and ChildHandle in the form of a Unicode string. If the
 116   driver specified by This has a user readable name in the language specified by
 117   Language, then a pointer to the controller name is returned in ControllerName,
 118   and EFI_SUCCESS is returned.  If the driver specified by This is not currently
 119   managing the controller specified by ControllerHandle and ChildHandle,
 120   then EFI_UNSUPPORTED is returned.  If the driver specified by This does not
 121   support the language specified by Language, then EFI_UNSUPPORTED is returned.
 122
 123   @param  This[in]              A pointer to the EFI_COMPONENT_NAME2_PROTOCOL or
 124                                 EFI_COMPONENT_NAME_PROTOCOL instance.
 125
 126   @param  ControllerHandle[in]  The handle of a controller that the driver
 127                                 specified by This is managing.  This handle
 128                                 specifies the controller whose name is to be
 129                                 returned.
 130
 131   @param  ChildHandle[in]       The handle of the child controller to retrieve
 132                                 the name of.  This is an optional parameter that
 133                                 may be NULL.  It will be NULL for device
 134                                 drivers.  It will also be NULL for a bus drivers
 135                                 that wish to retrieve the name of the bus
 136                                 controller.  It will not be NULL for a bus
 137                                 driver that wishes to retrieve the name of a
 138                                 child controller.
 139
 140   @param  Language[in]          A pointer to a Null-terminated ASCII string
 141                                 array indicating the language.  This is the
 142                                 language of the driver name that the caller is
 143                                 requesting, and it must match one of the
 144                                 languages specified in SupportedLanguages. The
 145                                 number of languages supported by a driver is up
 146                                 to the driver writer. Language is specified in
 147                                 RFC 4646 or ISO 639-2 language code format.
 148
 149   @param  ControllerName[out]   A pointer to the Unicode string to return.
 150                                 This Unicode string is the name of the
 151                                 controller specified by ControllerHandle and
 152                                 ChildHandle in the language specified by
 153                                 Language from the point of view of the driver
 154                                 specified by This.
 155
 156   @retval EFI_SUCCESS           The Unicode string for the user readable name in
 157                                 the language specified by Language for the
 158                                 driver specified by This was returned in
 159                                 DriverName.
 160
 161   @retval EFI_INVALID_PARAMETER ControllerHandle is NULL.
 162
 163   @retval EFI_INVALID_PARAMETER ChildHandle is not NULL and it is not a valid
 164                                 EFI_HANDLE.
 165
 166   @retval EFI_INVALID_PARAMETER Language is NULL.
 167
 168   @retval EFI_INVALID_PARAMETER ControllerName is NULL.
 169
 170   @retval EFI_UNSUPPORTED       The driver specified by This is not currently
 171                                 managing the controller specified by
 172                                 ControllerHandle and ChildHandle.
 173
 174   @retval EFI_UNSUPPORTED       The driver specified by This does not support
 175                                 the language specified by Language.
 176
 177 **/
 178 EFI_STATUS
 179 EFIAPI
 180 I2cHostComponentNameGetControllerName (
 181   IN  EFI_COMPONENT_NAME2_PROTOCOL                    *This,
 182   IN  EFI_HANDLE                                      ControllerHandle,
 183   IN  EFI_HANDLE                                      ChildHandle        OPTIONAL,
 184   IN  CHAR8                                           *Language,
 185   OUT CHAR16                                          **ControllerName
 186   )
 187 {
 188   return EFI_UNSUPPORTED;
 189 }
 190
 191 /**
 192   Tests to see if this driver supports a given controller. If a child device is provided,
 193   it further tests to see if this driver supports creating a handle for the specified child device.
 194
 195   This function checks to see if the driver specified by This supports the device specified by
 196   ControllerHandle. Drivers will typically use the device path attached to
 197   ControllerHandle and/or the services from the bus I/O abstraction attached to
 198   ControllerHandle to determine if the driver supports ControllerHandle. This function
 199   may be called many times during platform initialization. In order to reduce boot times, the tests
 200   performed by this function must be very small, and take as little time as possible to execute. This
 201   function must not change the state of any hardware devices, and this function must be aware that the
 202   device specified by ControllerHandle may already be managed by the same driver or a
 203   different driver. This function must match its calls to AllocatePages() with FreePages(),
 204   AllocatePool() with FreePool(), and OpenProtocol() with CloseProtocol().
 205   Since ControllerHandle may have been previously started by the same driver, if a protocol is
 206   already in the opened state, then it must not be closed with CloseProtocol(). This is required
 207   to guarantee the state of ControllerHandle is not modified by this function.
 208
 209   @param[in]  This                 A pointer to the EFI_DRIVER_BINDING_PROTOCOL instance.
 210   @param[in]  ControllerHandle     The handle of the controller to test. This handle
 211                                    must support a protocol interface that supplies
 212                                    an I/O abstraction to the driver.
 213   @param[in]  RemainingDevicePath  A pointer to the remaining portion of a device path.  This
 214                                    parameter is ignored by device drivers, and is optional for bus
 215                                    drivers. For bus drivers, if this parameter is not NULL, then
 216                                    the bus driver must determine if the bus controller specified
 217                                    by ControllerHandle and the child controller specified
 218                                    by RemainingDevicePath are both supported by this
 219                                    bus driver.
 220
 221   @retval EFI_SUCCESS              The device specified by ControllerHandle and
 222                                    RemainingDevicePath is supported by the driver specified by This.
 223   @retval EFI_ALREADY_STARTED      The device specified by ControllerHandle and
 224                                    RemainingDevicePath is already being managed by the driver
 225                                    specified by This.
 226   @retval EFI_ACCESS_DENIED        The device specified by ControllerHandle and
 227                                    RemainingDevicePath is already being managed by a different
 228                                    driver or an application that requires exclusive access.
 229                                    Currently not implemented.
 230   @retval EFI_UNSUPPORTED          The device specified by ControllerHandle and
 231                                    RemainingDevicePath is not supported by the driver specified by This.
 232 **/
 233 EFI_STATUS
 234 EFIAPI
 235 I2cHostDriverSupported (
 236   IN EFI_DRIVER_BINDING_PROTOCOL  *This,
 237   IN EFI_HANDLE                   Controller,
 238   IN EFI_DEVICE_PATH_PROTOCOL     *RemainingDevicePath
 239   )
 240 {
 241   EFI_I2C_MASTER_PROTOCOL                       *I2cMaster;
 242   EFI_I2C_BUS_CONFIGURATION_MANAGEMENT_PROTOCOL *I2cBusConfigurationManagement;
 243   EFI_STATUS                                    Status;
 244
 245   //
 246   //  Locate I2C Bus Configuration Management Protocol
 247   //
 248   Status = gBS->OpenProtocol (
 249                   Controller,
 250                   &gEfiI2cBusConfigurationManagementProtocolGuid,
 251                   (VOID **)&I2cBusConfigurationManagement,
 252                   This->DriverBindingHandle,
 253                   Controller,
 254                   EFI_OPEN_PROTOCOL_BY_DRIVER
 255                   );
 256   if (EFI_ERROR (Status)) {
 257     return Status;
 258   }
 259
 260   //
 261   // Close the protocol because we don't use it here
 262   //
 263   gBS->CloseProtocol (
 264                   Controller,
 265                   &gEfiI2cBusConfigurationManagementProtocolGuid,
 266                   This->DriverBindingHandle,
 267                   Controller
 268                   );
 269
 270   //
 271   //  Locate I2C Master Protocol
 272   //
 273   Status = gBS->OpenProtocol (
 274                   Controller,
 275                   &gEfiI2cMasterProtocolGuid,
 276                   (VOID **)&I2cMaster,
 277                   This->DriverBindingHandle,
 278                   Controller,
 279                   EFI_OPEN_PROTOCOL_GET_PROTOCOL
 280                   );
 281   if (EFI_ERROR (Status)) {
 282     return Status;
 283   }
 284
 285   return EFI_SUCCESS;
 286 }
 287
 288 /**
 289   Starts a device controller or a bus controller.
 290
 291   The Start() function is designed to be invoked from the EFI boot service ConnectController().
 292   As a result, much of the error checking on the parameters to Start() has been moved into this
 293   common boot service. It is legal to call Start() from other locations,
 294   but the following calling restrictions must be followed, or the system behavior will not be deterministic.
 295   1. ControllerHandle must be a valid EFI_HANDLE.
 296   2. If RemainingDevicePath is not NULL, then it must be a pointer to a naturally aligned
 297      EFI_DEVICE_PATH_PROTOCOL.
 298   3. Prior to calling Start(), the Supported() function for the driver specified by This must
 299      have been called with the same calling parameters, and Supported() must have returned EFI_SUCCESS.
 300
 301   @param[in]  This                 A pointer to the EFI_DRIVER_BINDING_PROTOCOL instance.
 302   @param[in]  ControllerHandle     The handle of the controller to start. This handle
 303                                    must support a protocol interface that supplies
 304                                    an I/O abstraction to the driver.
 305   @param[in]  RemainingDevicePath  A pointer to the remaining portion of a device path.  This
 306                                    parameter is ignored by device drivers, and is optional for bus
 307                                    drivers. For a bus driver, if this parameter is NULL, then handles
 308                                    for all the children of Controller are created by this driver.
 309                                    If this parameter is not NULL and the first Device Path Node is
 310                                    not the End of Device Path Node, then only the handle for the
 311                                    child device specified by the first Device Path Node of
 312                                    RemainingDevicePath is created by this driver.
 313                                    If the first Device Path Node of RemainingDevicePath is
 314                                    the End of Device Path Node, no child handle is created by this
 315                                    driver.
 316
 317   @retval EFI_SUCCESS              The device was started.
 318   @retval EFI_DEVICE_ERROR         The device could not be started due to a device error.Currently not implemented.
 319   @retval EFI_OUT_OF_RESOURCES     The request could not be completed due to a lack of resources.
 320   @retval Others                   The driver failded to start the device.
 321
 322 **/
 323 EFI_STATUS
 324 EFIAPI
 325 I2cHostDriverStart (
 326   IN EFI_DRIVER_BINDING_PROTOCOL        *This,
 327   IN EFI_HANDLE                         Controller,
 328   IN EFI_DEVICE_PATH_PROTOCOL           *RemainingDevicePath
 329   )
 330 {
 331   EFI_STATUS                                          Status;
 332   EFI_I2C_MASTER_PROTOCOL                             *I2cMaster;
 333   EFI_I2C_BUS_CONFIGURATION_MANAGEMENT_PROTOCOL       *I2cBusConfigurationManagement;
 334   I2C_HOST_CONTEXT                                    *I2cHostContext;
 335
 336   I2cMaster                     = NULL;
 337   I2cHostContext                = NULL;
 338   I2cBusConfigurationManagement = NULL;
 339
 340   //
 341   // Locate I2C Bus Configuration Management Protocol
 342   //
 343   Status = gBS->OpenProtocol (
 344                   Controller,
 345                   &gEfiI2cBusConfigurationManagementProtocolGuid,
 346                   (VOID **)&I2cBusConfigurationManagement,
 347                   This->DriverBindingHandle,
 348                   Controller,
 349                   EFI_OPEN_PROTOCOL_BY_DRIVER
 350                   );
 351   if (EFI_ERROR (Status)) {
 352     DEBUG ((EFI_D_ERROR, "I2cHost: Open I2C bus configuration error, Status = %r\n", Status));
 353     return Status;
 354   }
 355
 356   //
 357   // Locate I2C Master Protocol
 358   //
 359   Status = gBS->OpenProtocol (
 360                   Controller,
 361                   &gEfiI2cMasterProtocolGuid,
 362                   (VOID **)&I2cMaster,
 363                   This->DriverBindingHandle,
 364                   Controller,
 365                   EFI_OPEN_PROTOCOL_GET_PROTOCOL
 366                   );
 367   if (EFI_ERROR (Status)) {
 368     DEBUG ((EFI_D_ERROR, "I2cHost: Open I2C master error, Status = %r\n", Status));
 369     goto Exit;
 370   }
 371
 372   //
 373   // Allocate the I2C Host Context structure
 374   //
 375   I2cHostContext = AllocateZeroPool (sizeof (I2C_HOST_CONTEXT));
 376   if (I2cHostContext == NULL) {
 377     DEBUG ((EFI_D_ERROR, "I2cHost: there is no enough memory to allocate.\n"));
 378     Status = EFI_OUT_OF_RESOURCES;
 379     goto Exit;
 380   }
 381
 382   //
 383   // Initialize the context structure for the current I2C Controller
 384   //
 385   I2cHostContext->Signature                     = I2C_HOST_SIGNATURE;
 386   I2cHostContext->I2cMaster                     = I2cMaster;
 387   I2cHostContext->I2cBusConfigurationManagement = I2cBusConfigurationManagement;
 388   I2cHostContext->I2cBusConfiguration           = (UINTN) -1;
 389   InitializeListHead(&I2cHostContext->RequestList);
 390
 391   //
 392   // Reset the controller
 393   //
 394   Status = I2cMaster->Reset (I2cMaster);
 395   if (EFI_ERROR (Status)) {
 396     DEBUG ((EFI_D_ERROR, "I2cHost: I2C controller reset failed!\n"));
 397     goto Exit;
 398   }
 399
 400   //
 401   // Create the I2C transaction complete event
 402   //
 403   Status = gBS->CreateEvent (
 404                   EVT_NOTIFY_SIGNAL,
 405                   TPL_I2C_SYNC,
 406                   I2cHostRequestCompleteEvent,
 407                   I2cHostContext,
 408                   &I2cHostContext->I2cEvent
 409                   );
 410   if (EFI_ERROR (Status)) {
 411     DEBUG ((EFI_D_ERROR, "I2cHost: create complete event error, Status = %r\n", Status));
 412     goto Exit;
 413   }
 414
 415   //
 416   // Get the bus management event
 417   //
 418   Status = gBS->CreateEvent (
 419                   EVT_NOTIFY_SIGNAL,
 420                   TPL_I2C_SYNC,
 421                   I2cHostI2cBusConfigurationAvailable,
 422                   I2cHostContext,
 423                   &I2cHostContext->I2cBusConfigurationEvent
 424                   );
 425   if (EFI_ERROR (Status)) {
 426     DEBUG ((EFI_D_ERROR, "I2cHost: create bus available event error, Status = %r\n", Status));
 427     goto Exit;
 428   }
 429
 430   //
 431   // Build the I2C host protocol for the current I2C controller
 432   //
 433   I2cHostContext->I2cHost.QueueRequest              = I2cHostQueueRequest;
 434   I2cHostContext->I2cHost.I2cControllerCapabilities = I2cMaster->I2cControllerCapabilities;
 435
 436   //
 437   //  Install the driver protocol
 438   //
 439   Status = gBS->InstallMultipleProtocolInterfaces (
 440                   &Controller,
 441                   &gEfiI2cHostProtocolGuid,
 442                   &I2cHostContext->I2cHost,
 443                   NULL
 444                   );
 445 Exit:
 446   if (EFI_ERROR (Status)) {
 447     DEBUG ((EFI_D_ERROR, "I2cHost: Start() function failed, Status = %r\n", Status));
 448     if (I2cBusConfigurationManagement != NULL) {
 449       gBS->CloseProtocol (
 450                       Controller,
 451                       &gEfiI2cBusConfigurationManagementProtocolGuid,
 452                       This->DriverBindingHandle,
 453                       Controller
 454                       );
 455     }
 456
 457     if ((I2cHostContext != NULL) && (I2cHostContext->I2cEvent != NULL)) {
 458       gBS->CloseEvent (I2cHostContext->I2cEvent);
 459       I2cHostContext->I2cEvent = NULL;
 460     }
 461
 462     if ((I2cHostContext != NULL) && (I2cHostContext->I2cBusConfigurationEvent != NULL)) {
 463       gBS->CloseEvent (I2cHostContext->I2cBusConfigurationEvent);
 464       I2cHostContext->I2cBusConfigurationEvent = NULL;
 465     }
 466
 467     //
 468     //  Release the context structure upon failure
 469     //
 470     if (I2cHostContext != NULL) {
 471       FreePool (I2cHostContext);
 472     }
 473   }
 474
 475   //
 476   //  Return the operation status.
 477   //
 478   return Status;
 479 }
 480
 481 /**
 482   Stops a device controller or a bus controller.
 483
 484   The Stop() function is designed to be invoked from the EFI boot service DisconnectController().
 485   As a result, much of the error checking on the parameters to Stop() has been moved
 486   into this common boot service. It is legal to call Stop() from other locations,
 487   but the following calling restrictions must be followed, or the system behavior will not be deterministic.
 488   1. ControllerHandle must be a valid EFI_HANDLE that was used on a previous call to this
 489      same driver's Start() function.
 490   2. The first NumberOfChildren handles of ChildHandleBuffer must all be a valid
 491      EFI_HANDLE. In addition, all of these handles must have been created in this driver's
 492      Start() function, and the Start() function must have called OpenProtocol() on
 493      ControllerHandle with an Attribute of EFI_OPEN_PROTOCOL_BY_CHILD_CONTROLLER.
 494
 495   @param[in]  This              A pointer to the EFI_DRIVER_BINDING_PROTOCOL instance.
 496   @param[in]  ControllerHandle  A handle to the device being stopped. The handle must
 497                                 support a bus specific I/O protocol for the driver
 498                                 to use to stop the device.
 499   @param[in]  NumberOfChildren  The number of child device handles in ChildHandleBuffer.
 500   @param[in]  ChildHandleBuffer An array of child handles to be freed. May be NULL
 501                                 if NumberOfChildren is 0.
 502
 503   @retval EFI_SUCCESS           The device was stopped.
 504   @retval EFI_DEVICE_ERROR      The device could not be stopped due to a device error.
 505
 506 **/
 507 EFI_STATUS
 508 EFIAPI
 509 I2cHostDriverStop (
 510   IN  EFI_DRIVER_BINDING_PROTOCOL       *This,
 511   IN  EFI_HANDLE                        Controller,
 512   IN  UINTN                             NumberOfChildren,
 513   IN  EFI_HANDLE                        *ChildHandleBuffer
 514   )
 515 {
 516   EFI_STATUS                  Status;
 517   I2C_HOST_CONTEXT            *I2cHostContext;
 518   EFI_I2C_HOST_PROTOCOL       *I2cHost;
 519   EFI_TPL                     TplPrevious;
 520
 521   TplPrevious = EfiGetCurrentTpl ();
 522   if (TplPrevious > TPL_I2C_SYNC) {
 523     DEBUG ((EFI_D_ERROR, "I2cHost: TPL %d is too high in Stop.\n", TplPrevious));
 524     return EFI_DEVICE_ERROR;
 525   }
 526
 527   Status = gBS->OpenProtocol (
 528                   Controller,
 529                   &gEfiI2cHostProtocolGuid,
 530                   (VOID **) &I2cHost,
 531                   This->DriverBindingHandle,
 532                   Controller,
 533                   EFI_OPEN_PROTOCOL_GET_PROTOCOL
 534                   );
 535
 536   if (EFI_ERROR (Status)) {
 537     return EFI_DEVICE_ERROR;
 538   }
 539
 540   I2cHostContext = I2C_HOST_CONTEXT_FROM_PROTOCOL (I2cHost);
 541
 542   //
 543   // Raise TPL for critical section
 544   //
 545   TplPrevious = gBS->RaiseTPL (TPL_I2C_SYNC);
 546
 547   //
 548   // If there is pending request or pending bus configuration, do not stop
 549   //
 550   Status = EFI_DEVICE_ERROR;
 551   if (( !I2cHostContext->I2cBusConfigurationManagementPending )
 552     && IsListEmpty (&I2cHostContext->RequestList)) {
 553
 554     //
 555     //  Remove the I2C host protocol
 556     //
 557     Status = gBS->UninstallMultipleProtocolInterfaces (
 558                     Controller,
 559                     &gEfiI2cHostProtocolGuid,
 560                     I2cHost,
 561                     NULL
 562                     );
 563   }
 564
 565   //
 566   // Leave critical section
 567   //
 568   gBS->RestoreTPL (TplPrevious);
 569   if (!EFI_ERROR (Status)) {
 570     gBS->CloseProtocol (
 571            Controller,
 572            &gEfiI2cBusConfigurationManagementProtocolGuid,
 573            This->DriverBindingHandle,
 574            Controller
 575            );
 576
 577     //
 578     // Release I2c Host resources
 579     //
 580     if (I2cHostContext->I2cBusConfigurationEvent != NULL) {
 581       gBS->CloseEvent (I2cHostContext->I2cBusConfigurationEvent);
 582       I2cHostContext->I2cBusConfigurationEvent = NULL;
 583     }
 584
 585     if (I2cHostContext->I2cEvent != NULL) {
 586       gBS->CloseEvent (I2cHostContext->I2cEvent);
 587       I2cHostContext->I2cEvent = NULL;
 588     }
 589
 590     FreePool (I2cHostContext);
 591   }
 592
 593   //
 594   //  Return the stop status
 595   //
 596   return Status;
 597 }
 598
 599 /**
 600   Handle the I2C bus configuration available event
 601
 602   This routine is called at TPL_I2C_SYNC.
 603
 604   @param[in] Event    Address of an EFI_EVENT handle
 605   @param[in] Context  Address of an I2C_HOST_CONTEXT structure
 606
 607 **/
 608 VOID
 609 EFIAPI
 610 I2cHostI2cBusConfigurationAvailable (
 611   IN EFI_EVENT Event,
 612   IN VOID *Context
 613   )
 614 {
 615   I2C_HOST_CONTEXT            *I2cHostContext;
 616   EFI_I2C_MASTER_PROTOCOL     *I2cMaster;
 617   I2C_REQUEST                 *I2cRequest;
 618   LIST_ENTRY                  *EntryHeader;
 619   LIST_ENTRY                  *Entry;
 620   EFI_STATUS                  Status;
 621
 622   //
 623   // Mark this I2C bus configuration management operation as complete
 624   //
 625   I2cHostContext = (I2C_HOST_CONTEXT *)Context;
 626   I2cMaster      = I2cHostContext->I2cMaster;
 627   ASSERT (I2cMaster != NULL);
 628   //
 629   // Clear flag to indicate I2C bus configuration is finished
 630   //
 631   I2cHostContext->I2cBusConfigurationManagementPending = FALSE;
 632
 633   //
 634   //  Validate the completion status
 635   //
 636   if (EFI_ERROR (I2cHostContext->Status)) {
 637     //
 638     // Setting I2C bus configuration failed before
 639     //
 640     I2cHostRequestComplete (I2cHostContext, I2cHostContext->Status);
 641
 642     //
 643     // Unknown I2C bus configuration
 644     // Force next operation to enable the I2C bus configuration
 645     //
 646     I2cHostContext->I2cBusConfiguration = (UINTN) -1;
 647
 648     //
 649     // Do not continue current I2C request
 650     //
 651     return;
 652   }
 653
 654   //
 655   // Get the first request in the link with FIFO order
 656   //
 657   EntryHeader = &I2cHostContext->RequestList;
 658   Entry = GetFirstNode (EntryHeader);
 659   I2cRequest = I2C_REQUEST_FROM_ENTRY (Entry);
 660
 661   //
 662   // Update the I2C bus configuration of the current I2C request
 663   //
 664   I2cHostContext->I2cBusConfiguration = I2cRequest->I2cBusConfiguration;
 665
 666   //
 667   // Start an I2C operation on the host, the status is returned by I2cHostContext->Status
 668   //
 669   Status = I2cMaster->StartRequest (
 670                         I2cMaster,
 671                         I2cRequest->SlaveAddress,
 672                         I2cRequest->RequestPacket,
 673                         I2cHostContext->I2cEvent,
 674                         &I2cHostContext->Status
 675                         );
 676
 677   if (EFI_ERROR (Status)) {
 678     DEBUG((DEBUG_ERROR, "I2cHostI2cBusConfigurationAvailable: Error starting I2C operation, %r\n", Status));
 679   }
 680 }
 681
 682 /**
 683   Complete the current request
 684
 685   This routine is called at TPL_I2C_SYNC.
 686
 687   @param[in] I2cHostContext  Address of an I2C_HOST_CONTEXT structure.
 688   @param[in] Status          Status of the I2C operation.
 689
 690   @return This routine returns the input status value.
 691
 692 **/
 693 EFI_STATUS
 694 I2cHostRequestComplete (
 695   I2C_HOST_CONTEXT *I2cHostContext,
 696   EFI_STATUS       Status
 697   )
 698 {
 699   I2C_REQUEST *I2cRequest;
 700   LIST_ENTRY  *EntryHeader;
 701   LIST_ENTRY  *Entry;
 702
 703   //
 704   // Remove the current I2C request from the list
 705   //
 706   EntryHeader = &I2cHostContext->RequestList;
 707   Entry = GetFirstNode (EntryHeader);
 708   I2cRequest = I2C_REQUEST_FROM_ENTRY (Entry);
 709
 710   //
 711   // Save the status for QueueRequest
 712   //
 713   if ( NULL != I2cRequest->Status ) {
 714     *I2cRequest->Status = Status;
 715   }
 716
 717   //
 718   //  Notify the user of the I2C request completion
 719   //
 720   if ( NULL != I2cRequest->Event ) {
 721     gBS->SignalEvent (I2cRequest->Event);
 722   }
 723
 724   //
 725   // Done with this request, remove the current request from list
 726   //
 727   RemoveEntryList (&I2cRequest->Link);
 728   FreePool (I2cRequest->RequestPacket);
 729   FreePool (I2cRequest);
 730
 731   //
 732   // If there is more I2C request, start next one
 733   //
 734   if(!IsListEmpty (EntryHeader)) {
 735     I2cHostRequestEnable (I2cHostContext);
 736   }
 737
 738   return Status;
 739 }
 740
 741 /**
 742   Handle the bus available event
 743
 744   This routine is called at TPL_I2C_SYNC.
 745
 746   @param[in] Event    Address of an EFI_EVENT handle
 747   @param[in] Context  Address of an I2C_HOST_CONTEXT structure
 748
 749 **/
 750 VOID
 751 EFIAPI
 752 I2cHostRequestCompleteEvent (
 753   IN EFI_EVENT Event,
 754   IN VOID *Context
 755   )
 756 {
 757   I2C_HOST_CONTEXT *I2cHostContext;
 758
 759   //
 760   // Handle the completion event
 761   //
 762   I2cHostContext = (I2C_HOST_CONTEXT *)Context;
 763   I2cHostRequestComplete (I2cHostContext, I2cHostContext->Status);
 764 }
 765
 766 /**
 767   Enable access to the I2C bus configuration
 768
 769   @param[in] I2cHostContext     Address of an I2C_HOST_CONTEXT structure
 770
 771   @retval EFI_SUCCESS           The operation completed successfully.
 772   @retval EFI_ABORTED           The request did not complete because the driver
 773                                 was shutdown.
 774   @retval EFI_BAD_BUFFER_SIZE   The WriteBytes or ReadBytes buffer size is too large.
 775   @retval EFI_DEVICE_ERROR      There was an I2C error (NACK) during the operation.
 776                                 This could indicate the slave device is not present.
 777   @retval EFI_INVALID_PARAMETER RequestPacket is NULL
 778   @retval EFI_NO_MAPPING        Invalid I2cBusConfiguration value
 779   @retval EFI_NO_RESPONSE       The I2C device is not responding to the
 780                                 slave address.  EFI_DEVICE_ERROR may also be
 781                                 returned if the controller can not distinguish
 782                                 when the NACK occurred.
 783   @retval EFI_NOT_FOUND         I2C slave address exceeds maximum address
 784   @retval EFI_NOT_READY         I2C bus is busy or operation pending, wait for
 785                                 the event and then read status.
 786   @retval EFI_OUT_OF_RESOURCES  Insufficient memory for I2C operation
 787   @retval EFI_TIMEOUT           The transaction did not complete within an internally
 788                                 specified timeout period.
 789
 790 **/
 791 EFI_STATUS
 792 I2cHostRequestEnable (
 793   I2C_HOST_CONTEXT *I2cHostContext
 794   )
 795 {
 796   UINTN                                                 I2cBusConfiguration;
 797   CONST EFI_I2C_BUS_CONFIGURATION_MANAGEMENT_PROTOCOL   *I2cBusConfigurationManagement;
 798   I2C_REQUEST                                           *I2cRequest;
 799   EFI_STATUS                                            Status;
 800   EFI_TPL                                               TplPrevious;
 801   LIST_ENTRY                                            *EntryHeader;
 802   LIST_ENTRY                                            *Entry;
 803
 804   //
 805   //  Assume pending request
 806   //
 807   Status = EFI_NOT_READY;
 808
 809   I2cBusConfigurationManagement = I2cHostContext->I2cBusConfigurationManagement;
 810
 811   //
 812   //  Validate the I2c bus configuration
 813   //
 814   EntryHeader = &I2cHostContext->RequestList;
 815   Entry       = GetFirstNode (EntryHeader);
 816   I2cRequest = I2C_REQUEST_FROM_ENTRY (Entry);
 817
 818   I2cBusConfiguration = I2cRequest->I2cBusConfiguration;
 819
 820   if (I2cHostContext->I2cBusConfiguration != I2cBusConfiguration ) {
 821     //
 822     // Set flag to indicate I2C bus configuration is in progress
 823     //
 824     I2cHostContext->I2cBusConfigurationManagementPending = TRUE;
 825     //
 826     //  Update bus configuration for this device's requesting bus configuration
 827     //
 828     Status = I2cBusConfigurationManagement->EnableI2cBusConfiguration (
 829                 I2cBusConfigurationManagement,
 830                 I2cBusConfiguration,
 831                 I2cHostContext->I2cBusConfigurationEvent,
 832                 &I2cHostContext->Status
 833                 );
 834   } else {
 835     //
 836     //  I2C bus configuration is same, no need change configuration and start I2c transaction directly
 837     //
 838     TplPrevious = gBS->RaiseTPL ( TPL_I2C_SYNC );
 839
 840     //
 841     //  Same I2C bus configuration
 842     //
 843     I2cHostContext->Status = EFI_SUCCESS;
 844     I2cHostI2cBusConfigurationAvailable (I2cHostContext->I2cBusConfigurationEvent, I2cHostContext);
 845
 846     //
 847     //  Release the thread synchronization
 848     //
 849     gBS->RestoreTPL ( TplPrevious );
 850   }
 851   return Status;
 852 }
 853
 854 /**
 855   Queue an I2C operation for execution on the I2C controller.
 856
 857   This routine must be called at or below TPL_NOTIFY.  For synchronous
 858   requests this routine must be called at or below TPL_CALLBACK.
 859
 860   N.B. The typical consumers of this API are the I2C bus driver and
 861   on rare occasions the I2C test application.  Extreme care must be
 862   taken by other consumers of this API to prevent confusing the
 863   third party I2C drivers due to a state change at the I2C device
 864   which the third party I2C drivers did not initiate.  I2C platform
 865   drivers may use this API within these guidelines.
 866
 867   This layer uses the concept of I2C bus configurations to describe
 868   the I2C bus.  An I2C bus configuration is defined as a unique
 869   setting of the multiplexers and switches in the I2C bus which
 870   enable access to one or more I2C devices.  When using a switch
 871   to divide a bus, due to speed differences, the I2C platform layer
 872   would define an I2C bus configuration for the I2C devices on each
 873   side of the switch.  When using a multiplexer, the I2C platform
 874   layer defines an I2C bus configuration for each of the selector
 875   values required to control the multiplexer.  See Figure 1 in the
 876   <a href="http://www.nxp.com/documents/user_manual/UM10204.pdf">I<sup>2</sup>C
 877   Specification</a> for a complex I2C bus configuration.
 878
 879   The I2C host driver processes all operations in FIFO order.  Prior to
 880   performing the operation, the I2C host driver calls the I2C platform
 881   driver to reconfigure the switches and multiplexers in the I2C bus
 882   enabling access to the specified I2C device.  The I2C platform driver
 883   also selects the maximum bus speed for the device.  After the I2C bus
 884   is configured, the I2C host driver calls the I2C port driver to
 885   initialize the I2C controller and start the I2C operation.
 886
 887   @param[in] This             Address of an EFI_I2C_HOST_PROTOCOL instance.
 888   @param[in] I2cBusConfiguration  I2C bus configuration to access the I2C
 889                                   device.
 890   @param[in] SlaveAddress     Address of the device on the I2C bus.
 891   @param[in] Event            Event to set for asynchronous operations,
 892                               NULL for synchronous operations
 893   @param[in] RequestPacket    Address of an EFI_I2C_REQUEST_PACKET
 894                               structure describing the I2C operation
 895   @param[out] I2cStatus       Optional buffer to receive the I2C operation
 896                               completion status
 897
 898   @retval EFI_SUCCESS           The operation completed successfully.
 899   @retval EFI_BAD_BUFFER_SIZE   The WriteBytes or ReadBytes buffer size is too large.
 900   @retval EFI_DEVICE_ERROR      There was an I2C error (NACK) during the operation.
 901                                 This could indicate the slave device is not present.
 902   @retval EFI_INVALID_PARAMETER RequestPacket is NULL
 903   @retval EFI_INVALID_PARAMETER TPL is too high
 904   @retval EFI_NO_MAPPING        Invalid I2cBusConfiguration value
 905   @retval EFI_NO_RESPONSE       The I2C device is not responding to the
 906                                 slave address.  EFI_DEVICE_ERROR may also be
 907                                 returned if the controller can not distinguish
 908                                 when the NACK occurred.
 909   @retval EFI_NOT_FOUND         I2C slave address exceeds maximum address
 910   @retval EFI_NOT_READY         I2C bus is busy or operation pending, wait for
 911                                 the event and then read status pointed to by
 912                                 the request packet.
 913   @retval EFI_OUT_OF_RESOURCES  Insufficient memory for I2C operation
 914   @retval EFI_TIMEOUT           The transaction did not complete within an internally
 915                                 specified timeout period.
 916
 917 **/
 918 EFI_STATUS
 919 EFIAPI
 920 I2cHostQueueRequest (
 921   IN CONST EFI_I2C_HOST_PROTOCOL  *This,
 922   IN UINTN                        I2cBusConfiguration,
 923   IN UINTN                        SlaveAddress,
 924   IN EFI_EVENT                    Event            OPTIONAL,
 925   IN EFI_I2C_REQUEST_PACKET       *RequestPacket,
 926   OUT EFI_STATUS                  *I2cStatus       OPTIONAL
 927   )
 928 {
 929   EFI_STATUS        Status;
 930   EFI_EVENT         SyncEvent;
 931   EFI_TPL           TplPrevious;
 932   I2C_REQUEST       *I2cRequest;
 933   I2C_HOST_CONTEXT  *I2cHostContext;
 934   BOOLEAN           FirstRequest;
 935   UINTN             RequestPacketSize;
 936   UINTN             StartBit;
 937
 938   SyncEvent    = NULL;
 939   FirstRequest = FALSE;
 940   Status       = EFI_SUCCESS;
 941
 942   if (RequestPacket == NULL) {
 943     return EFI_INVALID_PARAMETER;
 944   }
 945
 946   if ((SlaveAddress & I2C_ADDRESSING_10_BIT) != 0) {
 947     //
 948     // 10-bit address, bits 0-9 are used for 10-bit I2C slave addresses,
 949     // bits 10-30 are reserved bits and must be zero
 950     //
 951     StartBit = 10;
 952   } else {
 953     //
 954     // 7-bit address, Bits 0-6 are used for 7-bit I2C slave addresses,
 955     // bits 7-30 are reserved bits and must be zero
 956     //
 957     StartBit = 7;
 958   }
 959
 960   if (BitFieldRead32 ((UINT32)SlaveAddress, StartBit, 30) != 0) {
 961     //
 962     // Reserved bit set in the SlaveAddress parameter
 963     //
 964     return EFI_NOT_FOUND;
 965   }
 966
 967   I2cHostContext = I2C_HOST_CONTEXT_FROM_PROTOCOL (This);
 968
 969   if (Event == NULL) {
 970     //
 971     // For synchronous transaction, register an event used to wait for finishing synchronous transaction
 972     //
 973     Status = gBS->CreateEvent (
 974                 0,
 975                 TPL_I2C_SYNC,
 976                 NULL,
 977                 NULL,
 978                 &SyncEvent
 979                 );
 980     if (EFI_ERROR (Status)) {
 981       return Status;
 982     }
 983   }
 984
 985   //
 986   // TPL should be at or below TPL_NOTIFY.
 987   // For synchronous requests this routine must be called at or below TPL_CALLBACK.
 988   //
 989   TplPrevious = EfiGetCurrentTpl ();
 990   if ((TplPrevious > TPL_I2C_SYNC) || ((Event == NULL) && (TplPrevious > TPL_CALLBACK))) {
 991     DEBUG ((EFI_D_ERROR, "ERROR - TPL %d is too high!\n", TplPrevious));
 992     return EFI_INVALID_PARAMETER;
 993   }
 994
 995   //
 996   // Allocate the request structure
 997   //
 998   I2cRequest = AllocateZeroPool (sizeof (I2C_REQUEST));
 999   if (I2cRequest == NULL) {
1000     DEBUG ((EFI_D_ERROR, "WARNING - Failed to allocate I2C_REQUEST!\n"));
1001     return EFI_OUT_OF_RESOURCES;
1002   }
1003
1004   //
1005   // Initialize the request
1006   //
1007   I2cRequest->Signature           = I2C_REQUEST_SIGNATURE;
1008   I2cRequest->I2cBusConfiguration = I2cBusConfiguration;
1009   I2cRequest->SlaveAddress        = SlaveAddress;
1010   I2cRequest->Event               = (Event == NULL) ? SyncEvent : Event;
1011   I2cRequest->Status              = I2cStatus;
1012
1013   //
1014   // Copy request packet into private buffer, as RequestPacket may be freed during asynchronous transaction
1015   //
1016   RequestPacketSize = sizeof (UINTN) + RequestPacket->OperationCount * sizeof (EFI_I2C_OPERATION);
1017   I2cRequest->RequestPacket = AllocateZeroPool (RequestPacketSize);
1018   ASSERT (I2cRequest->RequestPacket != NULL);
1019   CopyMem (I2cRequest->RequestPacket, RequestPacket, RequestPacketSize);
1020
1021   //
1022   // Synchronize with the other threads
1023   //
1024   gBS->RaiseTPL ( TPL_I2C_SYNC );
1025
1026   FirstRequest = IsListEmpty (&I2cHostContext->RequestList);
1027
1028   //
1029   // Insert new I2C request in the list
1030   //
1031   InsertTailList (&I2cHostContext->RequestList, &I2cRequest->Link);
1032
1033   //
1034   // Release the thread synchronization
1035   //
1036   gBS->RestoreTPL (TplPrevious);
1037
1038   if (FirstRequest) {
1039     //
1040     // Start the first I2C request, then the subsequent of I2C request will continue
1041     //
1042     Status = I2cHostRequestEnable (I2cHostContext);
1043   }
1044
1045   if (Event != NULL) {
1046     //
1047     // For asynchronous, return EFI_SUCCESS indicating that the asynchronously I2C transaction was queued.
1048     // No real I2C operation status in I2cStatus
1049     //
1050     return EFI_SUCCESS;
1051   }
1052
1053   //
1054   // For synchronous transaction, wait for the operation completion
1055   //
1056   do {
1057     Status = gBS->CheckEvent (SyncEvent);
1058   } while (Status == EFI_NOT_READY);
1059
1060   //
1061   // Get the I2C operation status
1062   //
1063   Status = I2cHostContext->Status;
1064
1065   //
1066   // Return the I2C operation status
1067   //
1068   if (I2cStatus != NULL) {
1069     *I2cStatus = Status;
1070   }
1071
1072   //
1073   // Close the event if necessary
1074   //
1075   if (SyncEvent != NULL) {
1076     gBS->CloseEvent (SyncEvent);
1077   }
1078
1079   return Status;
1080 }
1081
1082 /**
1083   The user Entry Point for I2C host module. The user code starts with this function.
1084
1085   @param[in] ImageHandle    The firmware allocated handle for the EFI image.
1086   @param[in] SystemTable    A pointer to the EFI System Table.
1087
1088   @retval EFI_SUCCESS       The entry point is executed successfully.
1089   @retval other             Some error occurs when executing this entry point.
1090
1091 **/
1092 EFI_STATUS
1093 EFIAPI
1094 InitializeI2cHost(
1095   IN EFI_HANDLE           ImageHandle,
1096   IN EFI_SYSTEM_TABLE     *SystemTable
1097   )
1098 {
1099   EFI_STATUS              Status;
1100
1101   //
1102   // Install driver model protocol(s).
1103   //
1104   Status = EfiLibInstallDriverBindingComponentName2 (
1105              ImageHandle,
1106              SystemTable,
1107              &gI2cHostDriverBinding,
1108              ImageHandle,
1109              &gI2cHostComponentName,
1110              &gI2cHostComponentName2
1111              );
1112   ASSERT_EFI_ERROR (Status);
1113   return Status;
1114 }
1115
1116 /**
1117   This is the unload handle for I2C host module.
1118
1119   Disconnect the driver specified by ImageHandle from all the devices in the handle database.
1120   Uninstall all the protocols installed in the driver entry point.
1121
1122   @param[in] ImageHandle           The drivers' driver image.
1123
1124   @retval    EFI_SUCCESS           The image is unloaded.
1125   @retval    Others                Failed to unload the image.
1126
1127 **/
1128 EFI_STATUS
1129 EFIAPI
1130 I2cHostUnload (
1131   IN EFI_HANDLE             ImageHandle
1132   )
1133 {
1134   EFI_STATUS                        Status;
1135   EFI_HANDLE                        *DeviceHandleBuffer;
1136   UINTN                             DeviceHandleCount;
1137   UINTN                             Index;
1138   EFI_COMPONENT_NAME_PROTOCOL       *ComponentName;
1139   EFI_COMPONENT_NAME2_PROTOCOL      *ComponentName2;
1140
1141   //
1142   // Get the list of all I2C Controller handles in the handle database.
1143   // If there is an error getting the list, then the unload
1144   // operation fails.
1145   //
1146   Status = gBS->LocateHandleBuffer (
1147                   ByProtocol,
1148                   &gEfiI2cHostProtocolGuid,
1149                   NULL,
1150                   &DeviceHandleCount,
1151                   &DeviceHandleBuffer
1152                   );
1153
1154   if (!EFI_ERROR (Status)) {
1155     //
1156     // Disconnect the driver specified by ImageHandle from all
1157     // the devices in the handle database.
1158     //
1159     for (Index = 0; Index < DeviceHandleCount; Index++) {
1160       Status = gBS->DisconnectController (
1161                       DeviceHandleBuffer[Index],
1162                       ImageHandle,
1163                       NULL
1164                       );
1165       if (EFI_ERROR (Status)) {
1166         goto Done;
1167       }
1168     }
1169   }
1170
1171   //
1172   // Uninstall all the protocols installed in the driver entry point
1173   //
1174   Status = gBS->UninstallMultipleProtocolInterfaces (
1175                   gI2cHostDriverBinding.DriverBindingHandle,
1176                   &gEfiDriverBindingProtocolGuid,
1177                   &gI2cHostDriverBinding,
1178                   NULL
1179                   );
1180   ASSERT_EFI_ERROR (Status);
1181
1182   //
1183   // Note we have to one by one uninstall the following protocols.
1184   // It's because some of them are optionally installed based on
1185   // the following PCD settings.
1186   //   gEfiMdePkgTokenSpaceGuid.PcdDriverDiagnosticsDisable
1187   //   gEfiMdePkgTokenSpaceGuid.PcdComponentNameDisable
1188   //   gEfiMdePkgTokenSpaceGuid.PcdDriverDiagnostics2Disable
1189   //   gEfiMdePkgTokenSpaceGuid.PcdComponentName2Disable
1190   //
1191   Status = gBS->HandleProtocol (
1192                   gI2cHostDriverBinding.DriverBindingHandle,
1193                   &gEfiComponentNameProtocolGuid,
1194                   (VOID **) &ComponentName
1195                   );
1196   if (!EFI_ERROR (Status)) {
1197     gBS->UninstallProtocolInterface (
1198            gI2cHostDriverBinding.DriverBindingHandle,
1199            &gEfiComponentNameProtocolGuid,
1200            ComponentName
1201            );
1202   }
1203
1204   Status = gBS->HandleProtocol (
1205                   gI2cHostDriverBinding.DriverBindingHandle,
1206                   &gEfiComponentName2ProtocolGuid,
1207                   (VOID **) &ComponentName2
1208                   );
1209   if (!EFI_ERROR (Status)) {
1210     gBS->UninstallProtocolInterface (
1211            gI2cHostDriverBinding.DriverBindingHandle,
1212            &gEfiComponentName2ProtocolGuid,
1213            ComponentName2
1214            );
1215   }
1216
1217   Status = EFI_SUCCESS;
1218
1219 Done:
1220   //
1221   // Free the buffer containing the list of handles from the handle database
1222   //
1223   if (DeviceHandleBuffer != NULL) {
1224     gBS->FreePool (DeviceHandleBuffer);
1225   }
1226
1227   return Status;
1228 }