text: /*******************************************************************************
   *
   * Module Name: hwregs - Read/write access functions for the various ACPI
   *                       control and status registers.
   *
   ******************************************************************************/
  
  /******************************************************************************
   *
   * 1. Copyright Notice
   *
   * Some or all of this work - Copyright (c) 1999 - 2017, Intel Corp.
   * All rights reserved.
   *
   * 2. License
   *
   * 2.1. This is your license from Intel Corp. under its intellectual property
   * rights. You may have additional license terms from the party that provided
   * you this software, covering your right to use that party's intellectual
   * property rights.
   *
   * 2.2. Intel grants, free of charge, to any person ("Licensee") obtaining a
   * copy of the source code appearing in this file ("Covered Code") an
   * irrevocable, perpetual, worldwide license under Intel's copyrights in the
   * base code distributed originally by Intel ("Original Intel Code") to copy,
   * make derivatives, distribute, use and display any portion of the Covered
   * Code in any form, with the right to sublicense such rights; and
   *
   * 2.3. Intel grants Licensee a non-exclusive and non-transferable patent
   * license (with the right to sublicense), under only those claims of Intel
   * patents that are infringed by the Original Intel Code, to make, use, sell,
   * offer to sell, and import the Covered Code and derivative works thereof
   * solely to the minimum extent necessary to exercise the above copyright
   * license, and in no event shall the patent license extend to any additions
   * to or modifications of the Original Intel Code. No other license or right
   * is granted directly or by implication, estoppel or otherwise;
   *
   * The above copyright and patent license is granted only if the following
   * conditions are met:
   *
   * 3. Conditions
   *
   * 3.1. Redistribution of Source with Rights to Further Distribute Source.
   * Redistribution of source code of any substantial portion of the Covered
   * Code or modification with rights to further distribute source must include
   * the above Copyright Notice, the above License, this list of Conditions,
   * and the following Disclaimer and Export Compliance provision. In addition,
   * Licensee must cause all Covered Code to which Licensee contributes to
   * contain a file documenting the changes Licensee made to create that Covered
   * Code and the date of any change. Licensee must include in that file the
   * documentation of any changes made by any predecessor Licensee. Licensee
   * must include a prominent statement that the modification is derived,
   * directly or indirectly, from Original Intel Code.
   *
   * 3.2. Redistribution of Source with no Rights to Further Distribute Source.
   * Redistribution of source code of any substantial portion of the Covered
   * Code or modification without rights to further distribute source must
   * include the following Disclaimer and Export Compliance provision in the
   * documentation and/or other materials provided with distribution. In
   * addition, Licensee may not authorize further sublicense of source of any
   * portion of the Covered Code, and must include terms to the effect that the
   * license from Licensee to its licensee is limited to the intellectual
   * property embodied in the software Licensee provides to its licensee, and
   * not to intellectual property embodied in modifications its licensee may
   * make.
   *
   * 3.3. Redistribution of Executable. Redistribution in executable form of any
   * substantial portion of the Covered Code or modification must reproduce the
   * above Copyright Notice, and the following Disclaimer and Export Compliance
   * provision in the documentation and/or other materials provided with the
   * distribution.
   *
   * 3.4. Intel retains all right, title, and interest in and to the Original
   * Intel Code.
   *
   * 3.5. Neither the name Intel nor any other trademark owned or controlled by
   * Intel shall be used in advertising or otherwise to promote the sale, use or
   * other dealings in products derived from or relating to the Covered Code
   * without prior written authorization from Intel.
   *
   * 4. Disclaimer and Export Compliance
   *
   * 4.1. INTEL MAKES NO WARRANTY OF ANY KIND REGARDING ANY SOFTWARE PROVIDED
   * HERE. ANY SOFTWARE ORIGINATING FROM INTEL OR DERIVED FROM INTEL SOFTWARE
   * IS PROVIDED "AS IS," AND INTEL WILL NOT PROVIDE ANY SUPPORT, ASSISTANCE,
   * INSTALLATION, TRAINING OR OTHER SERVICES. INTEL WILL NOT PROVIDE ANY
   * UPDATES, ENHANCEMENTS OR EXTENSIONS. INTEL SPECIFICALLY DISCLAIMS ANY
   * IMPLIED WARRANTIES OF MERCHANTABILITY, NONINFRINGEMENT AND FITNESS FOR A
   * PARTICULAR PURPOSE.
   *
   * 4.2. IN NO EVENT SHALL INTEL HAVE ANY LIABILITY TO LICENSEE, ITS LICENSEES
   * OR ANY OTHER THIRD PARTY, FOR ANY LOST PROFITS, LOST DATA, LOSS OF USE OR
   * COSTS OF PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, OR FOR ANY INDIRECT,
   * SPECIAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THIS AGREEMENT, UNDER ANY
   * CAUSE OF ACTION OR THEORY OF LIABILITY, AND IRRESPECTIVE OF WHETHER INTEL
   * HAS ADVANCE NOTICE OF THE POSSIBILITY OF SUCH DAMAGES. THESE LIMITATIONS
   * SHALL APPLY NOTWITHSTANDING THE FAILURE OF THE ESSENTIAL PURPOSE OF ANY
   * LIMITED REMEDY.
   *
   * 4.3. Licensee shall not export, either directly or indirectly, any of this
   * software or system incorporating such software without first obtaining any
   * required license or other approval from the U. S. Department of Commerce or
   * any other agency or department of the United States Government. In the
   * event Licensee exports any such software from the United States or
   * re-exports any such software from a foreign destination, Licensee shall
   * ensure that the distribution and export/re-export of the software is in
   * compliance with all laws, regulations, orders, or other restrictions of the
   * U.S. Export Administration Regulations. Licensee agrees that neither it nor
   * any of its subsidiaries will export/re-export any technical data, process,
   * software, or service, directly or indirectly, to any country for which the
   * United States government or any agency thereof requires an export license,
   * other governmental approval, or letter of assurance, without first obtaining
   * such license, approval or letter.
   *
   *****************************************************************************
   *
   * Alternatively, you may choose to be licensed under the terms of the
   * following license:
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions, and the following disclaimer,
   *    without modification.
   * 2. Redistributions in binary form must reproduce at minimum a disclaimer
   *    substantially similar to the "NO WARRANTY" disclaimer below
   *    ("Disclaimer") and any redistribution must be conditioned upon
   *    including a substantially similar Disclaimer requirement for further
   *    binary redistribution.
   * 3. Neither the names of the above-listed copyright holders nor the names
   *    of any contributors may be used to endorse or promote products derived
   *    from this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
   * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
   * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   *
   * Alternatively, you may choose to be licensed under the terms of the
   * GNU General Public License ("GPL") version 2 as published by the Free
   * Software Foundation.
   *
   *****************************************************************************/
  
  #include "acpi.h"
  #include "accommon.h"
  #include "acevents.h"
  
  #define _COMPONENT          ACPI_HARDWARE
          ACPI_MODULE_NAME    ("hwregs")
  
  
  #if (!ACPI_REDUCED_HARDWARE)
  
  /* Local Prototypes */
  
  static UINT8
  AcpiHwGetAccessBitWidth (
      UINT64                  Address,
      ACPI_GENERIC_ADDRESS    *Reg,
      UINT8                   MaxBitWidth);
  
  static ACPI_STATUS
  AcpiHwReadMultiple (
      UINT32                  *Value,
      ACPI_GENERIC_ADDRESS    *RegisterA,
      ACPI_GENERIC_ADDRESS    *RegisterB);
  
  static ACPI_STATUS
  AcpiHwWriteMultiple (
      UINT32                  Value,
      ACPI_GENERIC_ADDRESS    *RegisterA,
      ACPI_GENERIC_ADDRESS    *RegisterB);
  
  #endif /* !ACPI_REDUCED_HARDWARE */
  
  
  /******************************************************************************
   *
   * FUNCTION:    AcpiHwGetAccessBitWidth
   *
   * PARAMETERS:  Address             - GAS register address
   *              Reg                 - GAS register structure
   *              MaxBitWidth         - Max BitWidth supported (32 or 64)
   *
   * RETURN:      Status
   *
   * DESCRIPTION: Obtain optimal access bit width
   *
   ******************************************************************************/
  
  static UINT8
  AcpiHwGetAccessBitWidth (
      UINT64                  Address,
      ACPI_GENERIC_ADDRESS    *Reg,
      UINT8                   MaxBitWidth)
  {
      UINT8                   AccessBitWidth;
  
  
      /*
       * GAS format "register", used by FADT:
       *  1. Detected if BitOffset is 0 and BitWidth is 8/16/32/64;
       *  2. AccessSize field is ignored and BitWidth field is used for
       *     determining the boundary of the IO accesses.
       * GAS format "region", used by APEI registers:
       *  1. Detected if BitOffset is not 0 or BitWidth is not 8/16/32/64;
       *  2. AccessSize field is used for determining the boundary of the
       *     IO accesses;
       *  3. BitOffset/BitWidth fields are used to describe the "region".
       *
       * Note: This algorithm assumes that the "Address" fields should always
       *       contain aligned values.
       */
      if (!Reg->BitOffset && Reg->BitWidth &&
          ACPI_IS_POWER_OF_TWO (Reg->BitWidth) &&
          ACPI_IS_ALIGNED (Reg->BitWidth, 8))
      {
          AccessBitWidth = Reg->BitWidth;
      }
      else if (Reg->AccessWidth)
      {
          AccessBitWidth = ACPI_ACCESS_BIT_WIDTH (Reg->AccessWidth);
      }
      else
      {
          AccessBitWidth = ACPI_ROUND_UP_POWER_OF_TWO_8 (
              Reg->BitOffset + Reg->BitWidth);
          if (AccessBitWidth <= 8)
          {
              AccessBitWidth = 8;
          }
          else
          {
              while (!ACPI_IS_ALIGNED (Address, AccessBitWidth >> 3))
              {
                  AccessBitWidth >>= 1;
              }
          }
      }
  
      /* Maximum IO port access bit width is 32 */
  
      if (Reg->SpaceId == ACPI_ADR_SPACE_SYSTEM_IO)
      {
          MaxBitWidth = 32;
      }
  
      /*
       * Return access width according to the requested maximum access bit width,
       * as the caller should know the format of the register and may enforce
       * a 32-bit accesses.
       */
      if (AccessBitWidth < MaxBitWidth)
      {
          return (AccessBitWidth);
      }
      return (MaxBitWidth);
  }
  
  
  /******************************************************************************
   *
   * FUNCTION:    AcpiHwValidateRegister
   *
   * PARAMETERS:  Reg                 - GAS register structure
   *              MaxBitWidth         - Max BitWidth supported (32 or 64)
   *              Address             - Pointer to where the gas->address
   *                                    is returned
   *
   * RETURN:      Status
   *
   * DESCRIPTION: Validate the contents of a GAS register. Checks the GAS
   *              pointer, Address, SpaceId, BitWidth, and BitOffset.
   *
   ******************************************************************************/
  
  ACPI_STATUS
  AcpiHwValidateRegister (
      ACPI_GENERIC_ADDRESS    *Reg,
      UINT8                   MaxBitWidth,
      UINT64                  *Address)
  {
      UINT8                   BitWidth;
      UINT8                   AccessWidth;
  
  
      /* Must have a valid pointer to a GAS structure */
  
      if (!Reg)
      {
          return (AE_BAD_PARAMETER);
      }
  
      /*
       * Copy the target address. This handles possible alignment issues.
       * Address must not be null. A null address also indicates an optional
       * ACPI register that is not supported, so no error message.
       */
      ACPI_MOVE_64_TO_64 (Address, &Reg->Address);
      if (!(*Address))
      {
          return (AE_BAD_ADDRESS);
      }
  
      /* Validate the SpaceID */
  
      if ((Reg->SpaceId != ACPI_ADR_SPACE_SYSTEM_MEMORY) &&
          (Reg->SpaceId != ACPI_ADR_SPACE_SYSTEM_IO))
      {
          ACPI_ERROR ((AE_INFO,
              "Unsupported address space: 0x%X", Reg->SpaceId));
          return (AE_SUPPORT);
      }
  
      /* Validate the AccessWidth */
  
      if (Reg->AccessWidth > 4)
      {
          ACPI_ERROR ((AE_INFO,
              "Unsupported register access width: 0x%X", Reg->AccessWidth));
          return (AE_SUPPORT);
      }
  
      /* Validate the BitWidth, convert AccessWidth into number of bits */
  
      AccessWidth = AcpiHwGetAccessBitWidth (*Address, Reg, MaxBitWidth);
      BitWidth = ACPI_ROUND_UP (Reg->BitOffset + Reg->BitWidth, AccessWidth);
      if (MaxBitWidth < BitWidth)
      {
          ACPI_WARNING ((AE_INFO,
              "Requested bit width 0x%X is smaller than register bit width 0x%X",
              MaxBitWidth, BitWidth));
          return (AE_SUPPORT);
      }
  
      return (AE_OK);
  }
  
  
  /******************************************************************************
   *
   * FUNCTION:    AcpiHwRead
   *
   * PARAMETERS:  Value               - Where the value is returned
   *              Reg                 - GAS register structure
   *
   * RETURN:      Status
   *
   * DESCRIPTION: Read from either memory or IO space. This is a 64-bit max
   *              version of AcpiRead.
   *
   * LIMITATIONS: <These limitations also apply to AcpiHwWrite>
   *      SpaceID must be SystemMemory or SystemIO.
   *
   ******************************************************************************/
  
  ACPI_STATUS
  AcpiHwRead (
      UINT64                  *Value,
      ACPI_GENERIC_ADDRESS    *Reg)
  {
      UINT64                  Address;
      UINT8                   AccessWidth;
      UINT32                  BitWidth;
      UINT8                   BitOffset;
      UINT64                  Value64;
      UINT32                  Value32;
      UINT8                   Index;
      ACPI_STATUS             Status;
  
  
      ACPI_FUNCTION_NAME (HwRead);
  
  
      /* Validate contents of the GAS register */
  
      Status = AcpiHwValidateRegister (Reg, 64, &Address);
      if (ACPI_FAILURE (Status))
      {
          return (Status);
      }
  
      /*
       * Initialize entire 64-bit return value to zero, convert AccessWidth
       * into number of bits based
       */
      *Value = 0;
      AccessWidth = AcpiHwGetAccessBitWidth (Address, Reg, 64);
      BitWidth = Reg->BitOffset + Reg->BitWidth;
      BitOffset = Reg->BitOffset;
  
      /*
       * Two address spaces supported: Memory or IO. PCI_Config is
       * not supported here because the GAS structure is insufficient
       */
      Index = 0;
      while (BitWidth)
      {
          if (BitOffset >= AccessWidth)
          {
              Value64 = 0;
              BitOffset -= AccessWidth;
          }
          else
          {
              if (Reg->SpaceId == ACPI_ADR_SPACE_SYSTEM_MEMORY)
              {
                  Status = AcpiOsReadMemory ((ACPI_PHYSICAL_ADDRESS)
                      Address + Index * ACPI_DIV_8 (AccessWidth),
                      &Value64, AccessWidth);
              }
              else /* ACPI_ADR_SPACE_SYSTEM_IO, validated earlier */
              {
                  Status = AcpiHwReadPort ((ACPI_IO_ADDRESS)
                      Address + Index * ACPI_DIV_8 (AccessWidth),
                      &Value32, AccessWidth);
                  Value64 = (UINT64) Value32;
              }
          }
  
          /*
           * Use offset style bit writes because "Index * AccessWidth" is
           * ensured to be less than 64-bits by AcpiHwValidateRegister().
           */
          ACPI_SET_BITS (Value, Index * AccessWidth,
              ACPI_MASK_BITS_ABOVE_64 (AccessWidth), Value64);
  
          BitWidth -= BitWidth > AccessWidth ? AccessWidth : BitWidth;
          Index++;
      }
  
      ACPI_DEBUG_PRINT ((ACPI_DB_IO,
          "Read:  %8.8X%8.8X width %2d from %8.8X%8.8X (%s)\n",
          ACPI_FORMAT_UINT64 (*Value), AccessWidth,
          ACPI_FORMAT_UINT64 (Address), AcpiUtGetRegionName (Reg->SpaceId)));
  
      return (Status);
  }
  
  
  /******************************************************************************
   *
   * FUNCTION:    AcpiHwWrite
   *
   * PARAMETERS:  Value               - Value to be written
   *              Reg                 - GAS register structure
   *
   * RETURN:      Status
   *
   * DESCRIPTION: Write to either memory or IO space. This is a 64-bit max
   *              version of AcpiWrite.
   *
   ******************************************************************************/
  
  ACPI_STATUS
  AcpiHwWrite (
      UINT64                  Value,
      ACPI_GENERIC_ADDRESS    *Reg)
  {
      UINT64                  Address;
      UINT8                   AccessWidth;
      UINT32                  BitWidth;
      UINT8                   BitOffset;
      UINT64                  Value64;
      UINT8                   Index;
      ACPI_STATUS             Status;
  
  
      ACPI_FUNCTION_NAME (HwWrite);
  
  
      /* Validate contents of the GAS register */
  
      Status = AcpiHwValidateRegister (Reg, 64, &Address);
      if (ACPI_FAILURE (Status))
      {
          return (Status);
      }
  
      /* Convert AccessWidth into number of bits based */
  
      AccessWidth = AcpiHwGetAccessBitWidth (Address, Reg, 64);
      BitWidth = Reg->BitOffset + Reg->BitWidth;
      BitOffset = Reg->BitOffset;
  
      /*
       * Two address spaces supported: Memory or IO. PCI_Config is
       * not supported here because the GAS structure is insufficient
       */
      Index = 0;
      while (BitWidth)
      {
          /*
           * Use offset style bit reads because "Index * AccessWidth" is
           * ensured to be less than 64-bits by AcpiHwValidateRegister().
           */
          Value64 = ACPI_GET_BITS (&Value, Index * AccessWidth,
              ACPI_MASK_BITS_ABOVE_64 (AccessWidth));
  
          if (BitOffset >= AccessWidth)
          {
              BitOffset -= AccessWidth;
          }
          else
          {
              if (Reg->SpaceId == ACPI_ADR_SPACE_SYSTEM_MEMORY)
              {
                  Status = AcpiOsWriteMemory ((ACPI_PHYSICAL_ADDRESS)
                      Address + Index * ACPI_DIV_8 (AccessWidth),
                      Value64, AccessWidth);
              }
              else /* ACPI_ADR_SPACE_SYSTEM_IO, validated earlier */
              {
                  Status = AcpiHwWritePort ((ACPI_IO_ADDRESS)
                      Address + Index * ACPI_DIV_8 (AccessWidth),
                      (UINT32) Value64, AccessWidth);
              }
          }
  
          /*
           * Index * AccessWidth is ensured to be less than 32-bits by
           * AcpiHwValidateRegister().
           */
          BitWidth -= BitWidth > AccessWidth ? AccessWidth : BitWidth;
          Index++;
      }
  
      ACPI_DEBUG_PRINT ((ACPI_DB_IO,
          "Wrote: %8.8X%8.8X width %2d   to %8.8X%8.8X (%s)\n",
          ACPI_FORMAT_UINT64 (Value), AccessWidth,
          ACPI_FORMAT_UINT64 (Address), AcpiUtGetRegionName (Reg->SpaceId)));
  
      return (Status);
  }
  
  
  #if (!ACPI_REDUCED_HARDWARE)
  /*******************************************************************************
   *
   * FUNCTION:    AcpiHwClearAcpiStatus
   *
   * PARAMETERS:  None
   *
   * RETURN:      Status
   *
   * DESCRIPTION: Clears all fixed and general purpose status bits
   *
   ******************************************************************************/
  
  ACPI_STATUS
  AcpiHwClearAcpiStatus (
      void)
  {
      ACPI_STATUS             Status;
      ACPI_CPU_FLAGS          LockFlags = 0;
  
  
      ACPI_FUNCTION_TRACE (HwClearAcpiStatus);
  
  
      ACPI_DEBUG_PRINT ((ACPI_DB_IO, "About to write %04X to %8.8X%8.8X\n",
          ACPI_BITMASK_ALL_FIXED_STATUS,
          ACPI_FORMAT_UINT64 (AcpiGbl_XPm1aStatus.Address)));
  
      LockFlags = AcpiOsAcquireLock (AcpiGbl_HardwareLock);
  
      /* Clear the fixed events in PM1 A/B */
  
      Status = AcpiHwRegisterWrite (ACPI_REGISTER_PM1_STATUS,
          ACPI_BITMASK_ALL_FIXED_STATUS);
  
      AcpiOsReleaseLock (AcpiGbl_HardwareLock, LockFlags);
  
      if (ACPI_FAILURE (Status))
      {
          goto Exit;
      }
  
      /* Clear the GPE Bits in all GPE registers in all GPE blocks */
  
      Status = AcpiEvWalkGpeList (AcpiHwClearGpeBlock, NULL);
  
  Exit:
      return_ACPI_STATUS (Status);
  }
  
  
  /*******************************************************************************
   *
   * FUNCTION:    AcpiHwGetBitRegisterInfo
   *
   * PARAMETERS:  RegisterId          - Index of ACPI Register to access
   *
   * RETURN:      The bitmask to be used when accessing the register
   *
   * DESCRIPTION: Map RegisterId into a register bitmask.
   *
   ******************************************************************************/
  
  ACPI_BIT_REGISTER_INFO *
  AcpiHwGetBitRegisterInfo (
      UINT32                  RegisterId)
  {
      ACPI_FUNCTION_ENTRY ();
  
  
      if (RegisterId > ACPI_BITREG_MAX)
      {
          ACPI_ERROR ((AE_INFO, "Invalid BitRegister ID: 0x%X", RegisterId));
          return (NULL);
      }
  
      return (&AcpiGbl_BitRegisterInfo[RegisterId]);
  }
  
  
  /******************************************************************************
   *
   * FUNCTION:    AcpiHwWritePm1Control
   *
   * PARAMETERS:  Pm1aControl         - Value to be written to PM1A control
   *              Pm1bControl         - Value to be written to PM1B control
   *
   * RETURN:      Status
   *
   * DESCRIPTION: Write the PM1 A/B control registers. These registers are
   *              different than than the PM1 A/B status and enable registers
   *              in that different values can be written to the A/B registers.
   *              Most notably, the SLP_TYP bits can be different, as per the
   *              values returned from the _Sx predefined methods.
   *
   ******************************************************************************/
  
  ACPI_STATUS
  AcpiHwWritePm1Control (
      UINT32                  Pm1aControl,
      UINT32                  Pm1bControl)
  {
      ACPI_STATUS             Status;
  
  
      ACPI_FUNCTION_TRACE (HwWritePm1Control);
  
  
      Status = AcpiHwWrite (Pm1aControl, &AcpiGbl_FADT.XPm1aControlBlock);
      if (ACPI_FAILURE (Status))
      {
          return_ACPI_STATUS (Status);
      }
  
      if (AcpiGbl_FADT.XPm1bControlBlock.Address)
      {
          Status = AcpiHwWrite (Pm1bControl, &AcpiGbl_FADT.XPm1bControlBlock);
      }
      return_ACPI_STATUS (Status);
  }
  
  
  /******************************************************************************
   *
   * FUNCTION:    AcpiHwRegisterRead
   *
   * PARAMETERS:  RegisterId          - ACPI Register ID
   *              ReturnValue         - Where the register value is returned
   *
   * RETURN:      Status and the value read.
   *
   * DESCRIPTION: Read from the specified ACPI register
   *
   ******************************************************************************/
  
  ACPI_STATUS
  AcpiHwRegisterRead (
      UINT32                  RegisterId,
      UINT32                  *ReturnValue)
  {
      UINT32                  Value = 0;
      UINT64                  Value64;
      ACPI_STATUS             Status;
  
  
      ACPI_FUNCTION_TRACE (HwRegisterRead);
  
  
      switch (RegisterId)
      {
      case ACPI_REGISTER_PM1_STATUS:           /* PM1 A/B: 16-bit access each */
  
          Status = AcpiHwReadMultiple (&Value,
              &AcpiGbl_XPm1aStatus,
              &AcpiGbl_XPm1bStatus);
          break;
  
      case ACPI_REGISTER_PM1_ENABLE:           /* PM1 A/B: 16-bit access each */
  
          Status = AcpiHwReadMultiple (&Value,
              &AcpiGbl_XPm1aEnable,
              &AcpiGbl_XPm1bEnable);
          break;
  
      case ACPI_REGISTER_PM1_CONTROL:          /* PM1 A/B: 16-bit access each */
  
          Status = AcpiHwReadMultiple (&Value,
              &AcpiGbl_FADT.XPm1aControlBlock,
              &AcpiGbl_FADT.XPm1bControlBlock);
  
          /*
           * Zero the write-only bits. From the ACPI specification, "Hardware
           * Write-Only Bits": "Upon reads to registers with write-only bits,
           * software masks out all write-only bits."
           */
          Value &= ~ACPI_PM1_CONTROL_WRITEONLY_BITS;
          break;
  
      case ACPI_REGISTER_PM2_CONTROL:          /* 8-bit access */
  
          Status = AcpiHwRead (&Value64, &AcpiGbl_FADT.XPm2ControlBlock);
          Value = (UINT32) Value64;
          break;
  
      case ACPI_REGISTER_PM_TIMER:             /* 32-bit access */
  
          Status = AcpiHwRead (&Value64, &AcpiGbl_FADT.XPmTimerBlock);
          Value = (UINT32) Value64;
          break;
  
      case ACPI_REGISTER_SMI_COMMAND_BLOCK:    /* 8-bit access */
  
          Status = AcpiHwReadPort (AcpiGbl_FADT.SmiCommand, &Value, 8);
          break;
  
      default:
  
          ACPI_ERROR ((AE_INFO, "Unknown Register ID: 0x%X",
              RegisterId));
          Status = AE_BAD_PARAMETER;
          break;
      }
  
      if (ACPI_SUCCESS (Status))
      {
          *ReturnValue = (UINT32) Value;
      }
  
      return_ACPI_STATUS (Status);
  }
  
  
  /******************************************************************************
   *
   * FUNCTION:    AcpiHwRegisterWrite
   *
   * PARAMETERS:  RegisterId          - ACPI Register ID
   *              Value               - The value to write
   *
   * RETURN:      Status
   *
   * DESCRIPTION: Write to the specified ACPI register
   *
   * NOTE: In accordance with the ACPI specification, this function automatically
   * preserves the value of the following bits, meaning that these bits cannot be
   * changed via this interface:
   *
   * PM1_CONTROL[0] = SCI_EN
   * PM1_CONTROL[9]
   * PM1_STATUS[11]
   *
   * ACPI References:
   * 1) Hardware Ignored Bits: When software writes to a register with ignored
   *      bit fields, it preserves the ignored bit fields
   * 2) SCI_EN: OSPM always preserves this bit position
   *
   ******************************************************************************/
  
  ACPI_STATUS
  AcpiHwRegisterWrite (
      UINT32                  RegisterId,
      UINT32                  Value)
  {
      ACPI_STATUS             Status;
      UINT32                  ReadValue;
      UINT64                  ReadValue64;
  
  
      ACPI_FUNCTION_TRACE (HwRegisterWrite);
  
  
      switch (RegisterId)
      {
      case ACPI_REGISTER_PM1_STATUS:           /* PM1 A/B: 16-bit access each */
          /*
           * Handle the "ignored" bit in PM1 Status. According to the ACPI
           * specification, ignored bits are to be preserved when writing.
           * Normally, this would mean a read/modify/write sequence. However,
           * preserving a bit in the status register is different. Writing a
           * one clears the status, and writing a zero preserves the status.
           * Therefore, we must always write zero to the ignored bit.
           *
           * This behavior is clarified in the ACPI 4.0 specification.
           */
          Value &= ~ACPI_PM1_STATUS_PRESERVED_BITS;
  
          Status = AcpiHwWriteMultiple (Value,
              &AcpiGbl_XPm1aStatus,
              &AcpiGbl_XPm1bStatus);
          break;
  
      case ACPI_REGISTER_PM1_ENABLE:           /* PM1 A/B: 16-bit access each */
  
          Status = AcpiHwWriteMultiple (Value,
              &AcpiGbl_XPm1aEnable,
              &AcpiGbl_XPm1bEnable);
          break;
  
      case ACPI_REGISTER_PM1_CONTROL:          /* PM1 A/B: 16-bit access each */
          /*
           * Perform a read first to preserve certain bits (per ACPI spec)
           * Note: This includes SCI_EN, we never want to change this bit
           */
          Status = AcpiHwReadMultiple (&ReadValue,
              &AcpiGbl_FADT.XPm1aControlBlock,
              &AcpiGbl_FADT.XPm1bControlBlock);
          if (ACPI_FAILURE (Status))
          {
              goto Exit;
          }
  
          /* Insert the bits to be preserved */
  
          ACPI_INSERT_BITS (Value, ACPI_PM1_CONTROL_PRESERVED_BITS, ReadValue);
  
          /* Now we can write the data */
  
          Status = AcpiHwWriteMultiple (Value,
              &AcpiGbl_FADT.XPm1aControlBlock,
              &AcpiGbl_FADT.XPm1bControlBlock);
          break;
  
      case ACPI_REGISTER_PM2_CONTROL:          /* 8-bit access */
          /*
           * For control registers, all reserved bits must be preserved,
           * as per the ACPI spec.
           */
          Status = AcpiHwRead (&ReadValue64, &AcpiGbl_FADT.XPm2ControlBlock);
          if (ACPI_FAILURE (Status))
          {
              goto Exit;
          }
          ReadValue = (UINT32) ReadValue64;
  
          /* Insert the bits to be preserved */
  
          ACPI_INSERT_BITS (Value, ACPI_PM2_CONTROL_PRESERVED_BITS, ReadValue);
  
          Status = AcpiHwWrite (Value, &AcpiGbl_FADT.XPm2ControlBlock);
          break;
  
      case ACPI_REGISTER_PM_TIMER:             /* 32-bit access */
  
          Status = AcpiHwWrite (Value, &AcpiGbl_FADT.XPmTimerBlock);
          break;
  
      case ACPI_REGISTER_SMI_COMMAND_BLOCK:    /* 8-bit access */
  
          /* SMI_CMD is currently always in IO space */
  
          Status = AcpiHwWritePort (AcpiGbl_FADT.SmiCommand, Value, 8);
          break;
  
      default:
  
          ACPI_ERROR ((AE_INFO, "Unknown Register ID: 0x%X",
              RegisterId));
          Status = AE_BAD_PARAMETER;
          break;
      }
  
  Exit:
      return_ACPI_STATUS (Status);
  }
  
  
  /******************************************************************************
   *
   * FUNCTION:    AcpiHwReadMultiple
   *
   * PARAMETERS:  Value               - Where the register value is returned
   *              RegisterA           - First ACPI register (required)
   *              RegisterB           - Second ACPI register (optional)
   *
   * RETURN:      Status
   *
   * DESCRIPTION: Read from the specified two-part ACPI register (such as PM1 A/B)
   *
   ******************************************************************************/
  
  static ACPI_STATUS
  AcpiHwReadMultiple (
      UINT32                  *Value,
      ACPI_GENERIC_ADDRESS    *RegisterA,
      ACPI_GENERIC_ADDRESS    *RegisterB)
  {
      UINT32                  ValueA = 0;
      UINT32                  ValueB = 0;
      UINT64                  Value64;
      ACPI_STATUS             Status;
  
  
      /* The first register is always required */
  
      Status = AcpiHwRead (&Value64, RegisterA);
      if (ACPI_FAILURE (Status))
      {
          return (Status);
      }
      ValueA = (UINT32) Value64;
  
      /* Second register is optional */
  
      if (RegisterB->Address)
      {
          Status = AcpiHwRead (&Value64, RegisterB);
          if (ACPI_FAILURE (Status))
          {
              return (Status);
          }
          ValueB = (UINT32) Value64;
      }
  
      /*
       * OR the two return values together. No shifting or masking is necessary,
       * because of how the PM1 registers are defined in the ACPI specification:
       *
       * "Although the bits can be split between the two register blocks (each
       * register block has a unique pointer within the FADT), the bit positions
       * are maintained. The register block with unimplemented bits (that is,
       * those implemented in the other register block) always returns zeros,
       * and writes have no side effects"
       */
      *Value = (ValueA | ValueB);
      return (AE_OK);
  }
  
  
  /******************************************************************************
   *
   * FUNCTION:    AcpiHwWriteMultiple
   *
   * PARAMETERS:  Value               - The value to write
   *              RegisterA           - First ACPI register (required)
   *              RegisterB           - Second ACPI register (optional)
   *
   * RETURN:      Status
   *
   * DESCRIPTION: Write to the specified two-part ACPI register (such as PM1 A/B)
   *
   ******************************************************************************/
  
  static ACPI_STATUS
  AcpiHwWriteMultiple (
      UINT32                  Value,
      ACPI_GENERIC_ADDRESS    *RegisterA,
      ACPI_GENERIC_ADDRESS    *RegisterB)
  {
      ACPI_STATUS             Status;
  
  
      /* The first register is always required */
  
      Status = AcpiHwWrite (Value, RegisterA);
      if (ACPI_FAILURE (Status))
      {
          return (Status);
      }
  
      /*
       * Second register is optional
       *
       * No bit shifting or clearing is necessary, because of how the PM1
       * registers are defined in the ACPI specification:
       *
       * "Although the bits can be split between the two register blocks (each
       * register block has a unique pointer within the FADT), the bit positions
       * are maintained. The register block with unimplemented bits (that is,
       * those implemented in the other register block) always returns zeros,
       * and writes have no side effects"
       */
      if (RegisterB->Address)
      {
          Status = AcpiHwWrite (Value, RegisterB);
      }
  
      return (Status);
  }
  
  #endif /* !ACPI_REDUCED_HARDWARE */
  