ArmPkg/Drivers/ArmScmiDxe/ScmiClockProtocol.c - third_party/edk2 - Git at Google

 /** @file

   Copyright (c) 2017-2018, Arm Limited. All rights reserved.

   This program and the accompanying materials
   are licensed and made available under the terms and conditions of the BSD License
   which accompanies this distribution.  The full text of the license may be found at
   http://opensource.org/licenses/bsd-license.php

   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.

   System Control and Management Interface V1.0
     http://infocenter.arm.com/help/topic/com.arm.doc.den0056a/
     DEN0056A_System_Control_and_Management_Interface.pdf
 **/

 #include <Library/BaseLib.h>
 #include <Library/DebugLib.h>
 #include <Library/UefiBootServicesTableLib.h>
 #include <Protocol/ArmScmiClockProtocol.h>

 #include "ArmScmiClockProtocolPrivate.h"
 #include "ScmiPrivate.h"

 /** Convert to 64 bit value from two 32 bit words.

   @param[in] Low   Lower 32 bits.
   @param[in] High  Higher 32 bits.

   @retval UINT64   64 bit value.
 **/
 STATIC
 UINT64
 ConvertTo64Bit (
   IN UINT32 Low,
   IN UINT32 High
   )
 {
    return (Low | ((UINT64)High << 32));
 }

 /** Return version of the clock management protocol supported by SCP firmware.

   @param[in]  This     A Pointer to SCMI_CLOCK_PROTOCOL Instance.

   @param[out] Version  Version of the supported SCMI Clock management protocol.

   @retval EFI_SUCCESS       The version is returned.
   @retval EFI_DEVICE_ERROR  SCP returns an SCMI error.
   @retval !(EFI_SUCCESS)    Other errors.
 **/
 STATIC
 EFI_STATUS
 ClockGetVersion (
   IN  SCMI_CLOCK_PROTOCOL  *This,
   OUT UINT32               *Version
   )
 {
   return ScmiGetProtocolVersion (SCMI_PROTOCOL_ID_CLOCK, Version);
 }

 /** Return total number of clock devices supported by the clock management
   protocol.

   @param[in]  This         A Pointer to SCMI_CLOCK_PROTOCOL Instance.

   @param[out] TotalClocks  Total number of clocks supported.

   @retval EFI_SUCCESS       Total number of clocks supported is returned.
   @retval EFI_DEVICE_ERROR  SCP returns an SCMI error.
   @retval !(EFI_SUCCESS)    Other errors.
 **/
 STATIC
 EFI_STATUS
 ClockGetTotalClocks (
   IN  SCMI_CLOCK_PROTOCOL  *This,
   OUT UINT32               *TotalClocks
   )
 {
   EFI_STATUS  Status;
   UINT32     *ReturnValues;

   Status = ScmiGetProtocolAttributes (SCMI_PROTOCOL_ID_CLOCK, &ReturnValues);
   if (EFI_ERROR (Status)) {
     return Status;
   }

   *TotalClocks = SCMI_CLOCK_PROTOCOL_TOTAL_CLKS (ReturnValues[0]);

   return EFI_SUCCESS;
 }

 /** Return attributes of a clock device.

   @param[in]  This        A Pointer to SCMI_CLOCK_PROTOCOL Instance.
   @param[in]  ClockId     Identifier for the clock device.

   @param[out] Enabled         If TRUE, the clock device is enabled.
   @param[out] ClockAsciiName  A NULL terminated ASCII string with the clock
                               name, of up to 16 bytes.

   @retval EFI_SUCCESS          Clock device attributes are returned.
   @retval EFI_DEVICE_ERROR     SCP returns an SCMI error.
   @retval !(EFI_SUCCESS)       Other errors.
 **/
 STATIC
 EFI_STATUS
 ClockGetClockAttributes (
   IN  SCMI_CLOCK_PROTOCOL  *This,
   IN  UINT32               ClockId,
   OUT BOOLEAN              *Enabled,
   OUT CHAR8                *ClockAsciiName
   )
 {
   EFI_STATUS          Status;

   UINT32              *MessageParams;
   CLOCK_ATTRIBUTES    *ClockAttributes;
   SCMI_COMMAND        Cmd;
   UINT32              PayloadLength;

   Status = ScmiCommandGetPayload (&MessageParams);
   if (EFI_ERROR (Status)) {
     return Status;
   }

   *MessageParams = ClockId;

   Cmd.ProtocolId = SCMI_PROTOCOL_ID_CLOCK;
   Cmd.MessageId  = SCMI_MESSAGE_ID_CLOCK_ATTRIBUTES;

   PayloadLength = sizeof (ClockId);

   Status = ScmiCommandExecute (
              &Cmd,
              &PayloadLength,
              (UINT32**)&ClockAttributes
              );
   if (EFI_ERROR (Status)) {
     return Status;
   }
    // TRUE if bit 0 of ClockAttributes->Attributes is set.
   *Enabled = CLOCK_ENABLED (ClockAttributes->Attributes);

   AsciiStrCpyS (
     ClockAsciiName,
     SCMI_MAX_STR_LEN,
     (CONST CHAR8*)ClockAttributes->ClockName
     );

   return EFI_SUCCESS;
 }

 /** Return list of rates supported by a given clock device.

   @param[in] This        A pointer to SCMI_CLOCK_PROTOCOL Instance.
   @param[in] ClockId     Identifier for the clock device.

   @param[out] Format      SCMI_CLOCK_RATE_FORMAT_DISCRETE: Clock device
                           supports range of clock rates which are non-linear.

                           SCMI_CLOCK_RATE_FORMAT_LINEAR: Clock device supports
                           range of linear clock rates from Min to Max in steps.

   @param[out] TotalRates  Total number of rates.

   @param[in,out] RateArraySize  Size of the RateArray.

   @param[out] RateArray   List of clock rates.

   @retval EFI_SUCCESS          List of clock rates is returned.
   @retval EFI_DEVICE_ERROR     SCP returns an SCMI error.
   @retval EFI_BUFFER_TOO_SMALL RateArraySize is too small for the result.
                                It has been updated to the size needed.
   @retval !(EFI_SUCCESS)       Other errors.
 **/
 STATIC
 EFI_STATUS
 ClockDescribeRates (
   IN     SCMI_CLOCK_PROTOCOL     *This,
   IN     UINT32                   ClockId,
   OUT    SCMI_CLOCK_RATE_FORMAT  *Format,
   OUT    UINT32                  *TotalRates,
   IN OUT UINT32                  *RateArraySize,
   OUT    SCMI_CLOCK_RATE         *RateArray
   )
 {
   EFI_STATUS             Status;

   UINT32                 PayloadLength;
   SCMI_COMMAND           Cmd;
   UINT32                 *MessageParams;
   CLOCK_DESCRIBE_RATES   *DescribeRates;
   CLOCK_RATE_DWORD       *Rate;

   UINT32                 RequiredArraySize = 0;
   UINT32                 RateIndex = 0;
   UINT32                 RateNo;
   UINT32                 RateOffset;

   *TotalRates = 0;

   Status = ScmiCommandGetPayload (&MessageParams);
   if (EFI_ERROR (Status)) {
     return Status;
   }

   Cmd.ProtocolId = SCMI_PROTOCOL_ID_CLOCK;
   Cmd.MessageId  = SCMI_MESSAGE_ID_CLOCK_DESCRIBE_RATES;

   *MessageParams++  = ClockId;

   do {

     *MessageParams = RateIndex;

     // Set Payload length, note PayloadLength is a IN/OUT parameter.
     PayloadLength  = sizeof (ClockId) + sizeof (RateIndex);

     // Execute and wait for response on a SCMI channel.
     Status = ScmiCommandExecute (
                &Cmd,
                &PayloadLength,
                (UINT32**)&DescribeRates
                );
     if (EFI_ERROR (Status)) {
       return Status;
     }

     if (*TotalRates == 0) {
       // In the first iteration we will get number of returned rates and number
       // of remaining rates. With this information calculate required size
       // for rate array. If provided RateArraySize is less, return an
       // error.

       *Format = RATE_FORMAT (DescribeRates->NumRatesFlags);

       *TotalRates = NUM_RATES (DescribeRates->NumRatesFlags)
                     + NUM_REMAIN_RATES (DescribeRates->NumRatesFlags);

       if (*Format == SCMI_CLOCK_RATE_FORMAT_DISCRETE) {
          RequiredArraySize = (*TotalRates) * sizeof (UINT64);
       } else {
          // We need to return triplet of 64 bit value for each rate
          RequiredArraySize = (*TotalRates) * 3 * sizeof (UINT64);
       }

       if (RequiredArraySize > (*RateArraySize)) {
         *RateArraySize = RequiredArraySize;
         return EFI_BUFFER_TOO_SMALL;
       }
     }

     RateOffset = 0;

     if (*Format == SCMI_CLOCK_RATE_FORMAT_DISCRETE) {
       for (RateNo = 0; RateNo < NUM_RATES (DescribeRates->NumRatesFlags); RateNo++) {
         Rate = &DescribeRates->Rates[RateOffset++];
         // Non-linear discrete rates.
         RateArray[RateIndex++].Rate = ConvertTo64Bit (Rate->Low, Rate->High);
       }
     } else {
       for (RateNo = 0; RateNo < NUM_RATES (DescribeRates->NumRatesFlags); RateNo++) {
         // Linear clock rates from minimum to maximum in steps
         // Minimum clock rate.
         Rate = &DescribeRates->Rates[RateOffset++];
         RateArray[RateIndex].Min = ConvertTo64Bit (Rate->Low, Rate->High);

         Rate = &DescribeRates->Rates[RateOffset++];
         // Maximum clock rate.
         RateArray[RateIndex].Max = ConvertTo64Bit (Rate->Low, Rate->High);

         Rate = &DescribeRates->Rates[RateOffset++];
         // Step.
         RateArray[RateIndex++].Step = ConvertTo64Bit (Rate->Low, Rate->High);
       }
     }
   } while (NUM_REMAIN_RATES (DescribeRates->NumRatesFlags) != 0);

   // Update RateArraySize with RequiredArraySize.
   *RateArraySize = RequiredArraySize;

   return EFI_SUCCESS;
 }

 /** Get clock rate.

   @param[in]  This        A Pointer to SCMI_CLOCK_PROTOCOL Instance.
   @param[in]  ClockId     Identifier for the clock device.

   @param[out]  Rate       Clock rate.

   @retval EFI_SUCCESS          Clock rate is returned.
   @retval EFI_DEVICE_ERROR     SCP returns an SCMI error.
   @retval !(EFI_SUCCESS)       Other errors.
 **/
 STATIC
 EFI_STATUS
 ClockRateGet (
   IN  SCMI_CLOCK_PROTOCOL  *This,
   IN  UINT32               ClockId,
   OUT UINT64               *Rate
   )
 {
   EFI_STATUS     Status;

   UINT32            *MessageParams;
   CLOCK_RATE_DWORD  *ClockRate;
   SCMI_COMMAND      Cmd;

   UINT32         PayloadLength;

   Status = ScmiCommandGetPayload (&MessageParams);
   if (EFI_ERROR (Status)) {
     return Status;
   }

   // Fill arguments for clock protocol command.
   *MessageParams  = ClockId;

   Cmd.ProtocolId  = SCMI_PROTOCOL_ID_CLOCK;
   Cmd.MessageId   = SCMI_MESSAGE_ID_CLOCK_RATE_GET;

   PayloadLength = sizeof (ClockId);

   // Execute and wait for response on a SCMI channel.
   Status = ScmiCommandExecute (
              &Cmd,
              &PayloadLength,
              (UINT32**)&ClockRate
              );
   if (EFI_ERROR (Status)) {
     return Status;
   }

   *Rate = ConvertTo64Bit (ClockRate->Low, ClockRate->High);

   return EFI_SUCCESS;
 }

 /** Set clock rate.

   @param[in]  This        A Pointer to SCMI_CLOCK_PROTOCOL Instance.
   @param[in]  ClockId     Identifier for the clock device.
   @param[in]  Rate        Clock rate.

   @retval EFI_SUCCESS          Clock rate set success.
   @retval EFI_DEVICE_ERROR     SCP returns an SCMI error.
   @retval !(EFI_SUCCESS)       Other errors.
 **/
 STATIC
 EFI_STATUS
 ClockRateSet (
   IN SCMI_CLOCK_PROTOCOL  *This,
   IN UINT32               ClockId,
   IN UINT64               Rate
   )
 {
   EFI_STATUS                  Status;
   CLOCK_RATE_SET_ATTRIBUTES   *ClockRateSetAttributes;
   SCMI_COMMAND                Cmd;
   UINT32                      PayloadLength;

   Status = ScmiCommandGetPayload ((UINT32**)&ClockRateSetAttributes);
   if (EFI_ERROR (Status)) {
     return Status;
   }

   // Fill arguments for clock protocol command.
   ClockRateSetAttributes->ClockId    = ClockId;
   ClockRateSetAttributes->Flags      = CLOCK_SET_DEFAULT_FLAGS;
   ClockRateSetAttributes->Rate.Low   = (UINT32)Rate;
   ClockRateSetAttributes->Rate.High  = (UINT32)(Rate >> 32);

   Cmd.ProtocolId = SCMI_PROTOCOL_ID_CLOCK;
   Cmd.MessageId  = SCMI_MESSAGE_ID_CLOCK_RATE_SET;

   PayloadLength = sizeof (CLOCK_RATE_SET_ATTRIBUTES);

   // Execute and wait for response on a SCMI channel.
   Status = ScmiCommandExecute (
              &Cmd,
              &PayloadLength,
              NULL
              );

   return Status;
 }

 // Instance of the SCMI clock management protocol.
 STATIC CONST SCMI_CLOCK_PROTOCOL ScmiClockProtocol = {
   ClockGetVersion,
   ClockGetTotalClocks,
   ClockGetClockAttributes,
   ClockDescribeRates,
   ClockRateGet,
   ClockRateSet
  };

 /** Initialize clock management protocol and install protocol on a given handle.

   @param[in] Handle              Handle to install clock management protocol.

   @retval EFI_SUCCESS            Clock protocol interface installed successfully.
 **/
 EFI_STATUS
 ScmiClockProtocolInit (
   IN EFI_HANDLE* Handle
   )
 {
   return gBS->InstallMultipleProtocolInterfaces (
                 Handle,
                 &gArmScmiClockProtocolGuid,
                 &ScmiClockProtocol,
                 NULL
                 );
 }
	/** @file

	Copyright (c) 2017-2018, Arm Limited. All rights reserved.

	This program and the accompanying materials
	are licensed and made available under the terms and conditions of the BSD License
	which accompanies this distribution. The full text of the license may be found at
	http://opensource.org/licenses/bsd-license.php

	THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
	WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.

	System Control and Management Interface V1.0
	http://infocenter.arm.com/help/topic/com.arm.doc.den0056a/
	DEN0056A_System_Control_and_Management_Interface.pdf
	**/

	#include <Library/BaseLib.h>
	#include <Library/DebugLib.h>
	#include <Library/UefiBootServicesTableLib.h>
	#include <Protocol/ArmScmiClockProtocol.h>

	#include "ArmScmiClockProtocolPrivate.h"
	#include "ScmiPrivate.h"

	/** Convert to 64 bit value from two 32 bit words.

	@param[in] Low Lower 32 bits.
	@param[in] High Higher 32 bits.

	@retval UINT64 64 bit value.
	**/
	STATIC
	UINT64
	ConvertTo64Bit (
	IN UINT32 Low,
	IN UINT32 High
	)
	{
	return (Low \| ((UINT64)High << 32));
	}

	/** Return version of the clock management protocol supported by SCP firmware.

	@param[in] This A Pointer to SCMI_CLOCK_PROTOCOL Instance.

	@param[out] Version Version of the supported SCMI Clock management protocol.

	@retval EFI_SUCCESS The version is returned.
	@retval EFI_DEVICE_ERROR SCP returns an SCMI error.
	@retval !(EFI_SUCCESS) Other errors.
	**/
	STATIC
	EFI_STATUS
	ClockGetVersion (
	IN SCMI_CLOCK_PROTOCOL *This,
	OUT UINT32 *Version
	)
	{
	return ScmiGetProtocolVersion (SCMI_PROTOCOL_ID_CLOCK, Version);
	}

	/** Return total number of clock devices supported by the clock management
	protocol.

	@param[in] This A Pointer to SCMI_CLOCK_PROTOCOL Instance.

	@param[out] TotalClocks Total number of clocks supported.

	@retval EFI_SUCCESS Total number of clocks supported is returned.
	@retval EFI_DEVICE_ERROR SCP returns an SCMI error.
	@retval !(EFI_SUCCESS) Other errors.
	**/
	STATIC
	EFI_STATUS
	ClockGetTotalClocks (
	IN SCMI_CLOCK_PROTOCOL *This,
	OUT UINT32 *TotalClocks
	)
	{
	EFI_STATUS Status;
	UINT32 *ReturnValues;

	Status = ScmiGetProtocolAttributes (SCMI_PROTOCOL_ID_CLOCK, &ReturnValues);
	if (EFI_ERROR (Status)) {
	return Status;
	}

	*TotalClocks = SCMI_CLOCK_PROTOCOL_TOTAL_CLKS (ReturnValues[0]);

	return EFI_SUCCESS;
	}

	/** Return attributes of a clock device.

	@param[in] This A Pointer to SCMI_CLOCK_PROTOCOL Instance.
	@param[in] ClockId Identifier for the clock device.

	@param[out] Enabled If TRUE, the clock device is enabled.
	@param[out] ClockAsciiName A NULL terminated ASCII string with the clock
	name, of up to 16 bytes.

	@retval EFI_SUCCESS Clock device attributes are returned.
	@retval EFI_DEVICE_ERROR SCP returns an SCMI error.
	@retval !(EFI_SUCCESS) Other errors.
	**/
	STATIC
	EFI_STATUS
	ClockGetClockAttributes (
	IN SCMI_CLOCK_PROTOCOL *This,
	IN UINT32 ClockId,
	OUT BOOLEAN *Enabled,
	OUT CHAR8 *ClockAsciiName
	)
	{
	EFI_STATUS Status;

	UINT32 *MessageParams;
	CLOCK_ATTRIBUTES *ClockAttributes;
	SCMI_COMMAND Cmd;
	UINT32 PayloadLength;

	Status = ScmiCommandGetPayload (&MessageParams);
	if (EFI_ERROR (Status)) {
	return Status;
	}

	*MessageParams = ClockId;

	Cmd.ProtocolId = SCMI_PROTOCOL_ID_CLOCK;
	Cmd.MessageId = SCMI_MESSAGE_ID_CLOCK_ATTRIBUTES;

	PayloadLength = sizeof (ClockId);

	Status = ScmiCommandExecute (
	&Cmd,
	&PayloadLength,
	(UINT32**)&ClockAttributes
	);
	if (EFI_ERROR (Status)) {
	return Status;
	}
	// TRUE if bit 0 of ClockAttributes->Attributes is set.
	*Enabled = CLOCK_ENABLED (ClockAttributes->Attributes);

	AsciiStrCpyS (
	ClockAsciiName,
	SCMI_MAX_STR_LEN,
	(CONST CHAR8*)ClockAttributes->ClockName
	);

	return EFI_SUCCESS;
	}

	/** Return list of rates supported by a given clock device.

	@param[in] This A pointer to SCMI_CLOCK_PROTOCOL Instance.
	@param[in] ClockId Identifier for the clock device.

	@param[out] Format SCMI_CLOCK_RATE_FORMAT_DISCRETE: Clock device
	supports range of clock rates which are non-linear.

	SCMI_CLOCK_RATE_FORMAT_LINEAR: Clock device supports
	range of linear clock rates from Min to Max in steps.

	@param[out] TotalRates Total number of rates.

	@param[in,out] RateArraySize Size of the RateArray.

	@param[out] RateArray List of clock rates.

	@retval EFI_SUCCESS List of clock rates is returned.
	@retval EFI_DEVICE_ERROR SCP returns an SCMI error.
	@retval EFI_BUFFER_TOO_SMALL RateArraySize is too small for the result.
	It has been updated to the size needed.
	@retval !(EFI_SUCCESS) Other errors.
	**/
	STATIC
	EFI_STATUS
	ClockDescribeRates (
	IN SCMI_CLOCK_PROTOCOL *This,
	IN UINT32 ClockId,
	OUT SCMI_CLOCK_RATE_FORMAT *Format,
	OUT UINT32 *TotalRates,
	IN OUT UINT32 *RateArraySize,
	OUT SCMI_CLOCK_RATE *RateArray
	)
	{
	EFI_STATUS Status;

	UINT32 PayloadLength;
	SCMI_COMMAND Cmd;
	UINT32 *MessageParams;
	CLOCK_DESCRIBE_RATES *DescribeRates;
	CLOCK_RATE_DWORD *Rate;

	UINT32 RequiredArraySize = 0;
	UINT32 RateIndex = 0;
	UINT32 RateNo;
	UINT32 RateOffset;

	*TotalRates = 0;

	Status = ScmiCommandGetPayload (&MessageParams);
	if (EFI_ERROR (Status)) {
	return Status;
	}

	Cmd.ProtocolId = SCMI_PROTOCOL_ID_CLOCK;
	Cmd.MessageId = SCMI_MESSAGE_ID_CLOCK_DESCRIBE_RATES;

	*MessageParams++ = ClockId;

	do {

	*MessageParams = RateIndex;

	// Set Payload length, note PayloadLength is a IN/OUT parameter.
	PayloadLength = sizeof (ClockId) + sizeof (RateIndex);

	// Execute and wait for response on a SCMI channel.
	Status = ScmiCommandExecute (
	&Cmd,
	&PayloadLength,
	(UINT32**)&DescribeRates
	);
	if (EFI_ERROR (Status)) {
	return Status;
	}

	if (*TotalRates == 0) {
	// In the first iteration we will get number of returned rates and number
	// of remaining rates. With this information calculate required size
	// for rate array. If provided RateArraySize is less, return an
	// error.

	*Format = RATE_FORMAT (DescribeRates->NumRatesFlags);

	*TotalRates = NUM_RATES (DescribeRates->NumRatesFlags)
	+ NUM_REMAIN_RATES (DescribeRates->NumRatesFlags);

	if (*Format == SCMI_CLOCK_RATE_FORMAT_DISCRETE) {
	RequiredArraySize = (TotalRates) sizeof (UINT64);
	} else {
	// We need to return triplet of 64 bit value for each rate
	RequiredArraySize = (TotalRates) 3 * sizeof (UINT64);
	}

	if (RequiredArraySize > (*RateArraySize)) {
	*RateArraySize = RequiredArraySize;
	return EFI_BUFFER_TOO_SMALL;
	}
	}

	RateOffset = 0;

	if (*Format == SCMI_CLOCK_RATE_FORMAT_DISCRETE) {
	for (RateNo = 0; RateNo < NUM_RATES (DescribeRates->NumRatesFlags); RateNo++) {
	Rate = &DescribeRates->Rates[RateOffset++];
	// Non-linear discrete rates.
	RateArray[RateIndex++].Rate = ConvertTo64Bit (Rate->Low, Rate->High);
	}
	} else {
	for (RateNo = 0; RateNo < NUM_RATES (DescribeRates->NumRatesFlags); RateNo++) {
	// Linear clock rates from minimum to maximum in steps
	// Minimum clock rate.
	Rate = &DescribeRates->Rates[RateOffset++];
	RateArray[RateIndex].Min = ConvertTo64Bit (Rate->Low, Rate->High);

	Rate = &DescribeRates->Rates[RateOffset++];
	// Maximum clock rate.
	RateArray[RateIndex].Max = ConvertTo64Bit (Rate->Low, Rate->High);

	Rate = &DescribeRates->Rates[RateOffset++];
	// Step.
	RateArray[RateIndex++].Step = ConvertTo64Bit (Rate->Low, Rate->High);
	}
	}
	} while (NUM_REMAIN_RATES (DescribeRates->NumRatesFlags) != 0);

	// Update RateArraySize with RequiredArraySize.
	*RateArraySize = RequiredArraySize;

	return EFI_SUCCESS;
	}

	/** Get clock rate.

	@param[in] This A Pointer to SCMI_CLOCK_PROTOCOL Instance.
	@param[in] ClockId Identifier for the clock device.

	@param[out] Rate Clock rate.

	@retval EFI_SUCCESS Clock rate is returned.
	@retval EFI_DEVICE_ERROR SCP returns an SCMI error.
	@retval !(EFI_SUCCESS) Other errors.
	**/
	STATIC
	EFI_STATUS
	ClockRateGet (
	IN SCMI_CLOCK_PROTOCOL *This,
	IN UINT32 ClockId,
	OUT UINT64 *Rate
	)
	{
	EFI_STATUS Status;

	UINT32 *MessageParams;
	CLOCK_RATE_DWORD *ClockRate;
	SCMI_COMMAND Cmd;

	UINT32 PayloadLength;

	Status = ScmiCommandGetPayload (&MessageParams);
	if (EFI_ERROR (Status)) {
	return Status;
	}

	// Fill arguments for clock protocol command.
	*MessageParams = ClockId;

	Cmd.ProtocolId = SCMI_PROTOCOL_ID_CLOCK;
	Cmd.MessageId = SCMI_MESSAGE_ID_CLOCK_RATE_GET;

	PayloadLength = sizeof (ClockId);

	// Execute and wait for response on a SCMI channel.
	Status = ScmiCommandExecute (
	&Cmd,
	&PayloadLength,
	(UINT32**)&ClockRate
	);
	if (EFI_ERROR (Status)) {
	return Status;
	}

	*Rate = ConvertTo64Bit (ClockRate->Low, ClockRate->High);

	return EFI_SUCCESS;
	}

	/** Set clock rate.

	@param[in] This A Pointer to SCMI_CLOCK_PROTOCOL Instance.
	@param[in] ClockId Identifier for the clock device.
	@param[in] Rate Clock rate.

	@retval EFI_SUCCESS Clock rate set success.
	@retval EFI_DEVICE_ERROR SCP returns an SCMI error.
	@retval !(EFI_SUCCESS) Other errors.
	**/
	STATIC
	EFI_STATUS
	ClockRateSet (
	IN SCMI_CLOCK_PROTOCOL *This,
	IN UINT32 ClockId,
	IN UINT64 Rate
	)
	{
	EFI_STATUS Status;
	CLOCK_RATE_SET_ATTRIBUTES *ClockRateSetAttributes;
	SCMI_COMMAND Cmd;
	UINT32 PayloadLength;

	Status = ScmiCommandGetPayload ((UINT32**)&ClockRateSetAttributes);
	if (EFI_ERROR (Status)) {
	return Status;
	}

	// Fill arguments for clock protocol command.
	ClockRateSetAttributes->ClockId = ClockId;
	ClockRateSetAttributes->Flags = CLOCK_SET_DEFAULT_FLAGS;
	ClockRateSetAttributes->Rate.Low = (UINT32)Rate;
	ClockRateSetAttributes->Rate.High = (UINT32)(Rate >> 32);

	Cmd.ProtocolId = SCMI_PROTOCOL_ID_CLOCK;
	Cmd.MessageId = SCMI_MESSAGE_ID_CLOCK_RATE_SET;

	PayloadLength = sizeof (CLOCK_RATE_SET_ATTRIBUTES);

	// Execute and wait for response on a SCMI channel.
	Status = ScmiCommandExecute (
	&Cmd,
	&PayloadLength,
	NULL
	);

	return Status;
	}

	// Instance of the SCMI clock management protocol.
	STATIC CONST SCMI_CLOCK_PROTOCOL ScmiClockProtocol = {
	ClockGetVersion,
	ClockGetTotalClocks,
	ClockGetClockAttributes,
	ClockDescribeRates,
	ClockRateGet,
	ClockRateSet
	};

	/** Initialize clock management protocol and install protocol on a given handle.

	@param[in] Handle Handle to install clock management protocol.

	@retval EFI_SUCCESS Clock protocol interface installed successfully.
	**/
	EFI_STATUS
	ScmiClockProtocolInit (
	IN EFI_HANDLE* Handle
	)
	{
	return gBS->InstallMultipleProtocolInterfaces (
	Handle,
	&gArmScmiClockProtocolGuid,
	&ScmiClockProtocol,
	NULL
	);
	}