[mirror_edk2.git] / Omap35xxPkg / TimerDxe / Timer.c

/** @file
  Template for Timer Architecture Protocol driver of the ARM flavor

  Copyright (c) 2008-2009, Apple Inc. All rights reserved.
  
  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.             

**/


#include <PiDxe.h>

#include <Library/BaseLib.h>
#include <Library/DebugLib.h>
#include <Library/BaseMemoryLib.h>
#include <Library/UefiBootServicesTableLib.h>
#include <Library/UefiLib.h>
#include <Library/PcdLib.h>
#include <Library/IoLib.h>
#include <Library/OmapLib.h>

#include <Protocol/Timer.h>
#include <Protocol/HardwareInterrupt.h>
#include <Protocol/TimerDebugSupport.h>

#include <Omap3530/Omap3530.h>


// The notification function to call on every timer interrupt.
volatile EFI_TIMER_NOTIFY      mTimerNotifyFunction   = (EFI_TIMER_NOTIFY)NULL;
volatile EFI_PERIODIC_CALLBACK mTimerPeriodicCallback = (EFI_PERIODIC_CALLBACK)NULL;


// The current period of the timer interrupt
volatile UINT64 mTimerPeriod = 0;

// Cached copy of the Hardware Interrupt protocol instance
EFI_HARDWARE_INTERRUPT_PROTOCOL *gInterrupt = NULL;

// Cached registers
volatile UINT32 TISR;
volatile UINT32 TCLR;
volatile UINT32 TLDR;
volatile UINT32 TCRR;
volatile UINT32 TIER;

// Cached interrupt vector
volatile UINTN  gVector;


/**\r
  C Interrupt Handler calledin the interrupt context when Source interrupt is active.\r
\r
  @param Source         Source of the interrupt. Hardware routing off a specific platform defines\r
                        what source means.\r
  @param SystemContext  Pointer to system register context. Mostly used by debuggers and will\r
                        update the system context after the return from the interrupt if \r
                        modified. Don't change these values unless you know what you are doing\r
\r
**/
VOID
EFIAPI
TimerInterruptHandler (
  IN  HARDWARE_INTERRUPT_SOURCE   Source,
  IN  EFI_SYSTEM_CONTEXT          SystemContext       
  )
{
  EFI_TPL OriginalTPL;\r
\r
  //\r
  // DXE core uses this callback for the EFI timer tick. The DXE core uses locks \r
  // that raise to TPL_HIGH and then restore back to current level. Thus we need\r
  // to make sure TPL level is set to TPL_HIGH while we are handling the timer tick. \r
  //\r
  OriginalTPL = gBS->RaiseTPL (TPL_HIGH_LEVEL);\r

  if (mTimerPeriodicCallback) {
    mTimerPeriodicCallback(SystemContext);
  }

  if (mTimerNotifyFunction) {
    mTimerNotifyFunction(mTimerPeriod);
  }

  // Clear all timer interrupts
  MmioWrite32(TISR, TISR_CLEAR_ALL);  

  // Poll interrupt status bits to ensure clearing
  while ((MmioRead32(TISR) & TISR_ALL_INTERRUPT_MASK) != TISR_NO_INTERRUPTS_PENDING);

  gBS->RestoreTPL (OriginalTPL);
}

/**\r
  This function registers the handler NotifyFunction so it is called every time \r
  the timer interrupt fires.  It also passes the amount of time since the last \r
  handler call to the NotifyFunction.  If NotifyFunction is NULL, then the \r
  handler is unregistered.  If the handler is registered, then EFI_SUCCESS is \r
  returned.  If the CPU does not support registering a timer interrupt handler, \r
  then EFI_UNSUPPORTED is returned.  If an attempt is made to register a handler \r
  when a handler is already registered, then EFI_ALREADY_STARTED is returned.  \r
  If an attempt is made to unregister a handler when a handler is not registered, \r
  then EFI_INVALID_PARAMETER is returned.  If an error occurs attempting to \r
  register the NotifyFunction with the timer interrupt, then EFI_DEVICE_ERROR \r
  is returned.\r
\r
  @param  This             The EFI_TIMER_ARCH_PROTOCOL instance.\r
  @param  NotifyFunction   The function to call when a timer interrupt fires. This\r
                           function executes at TPL_HIGH_LEVEL. The DXE Core will\r
                           register a handler for the timer interrupt, so it can know\r
                           how much time has passed. This information is used to\r
                           signal timer based events. NULL will unregister the handler.\r
\r
  @retval EFI_SUCCESS           The timer handler was registered.\r
  @retval EFI_UNSUPPORTED       The platform does not support timer interrupts.\r
  @retval EFI_ALREADY_STARTED   NotifyFunction is not NULL, and a handler is already\r
                                registered.\r
  @retval EFI_INVALID_PARAMETER NotifyFunction is NULL, and a handler was not\r
                                previously registered.\r
  @retval EFI_DEVICE_ERROR      The timer handler could not be registered.\r
\r
**/\r
EFI_STATUS
EFIAPI
TimerDriverRegisterHandler (
  IN EFI_TIMER_ARCH_PROTOCOL  *This,
  IN EFI_TIMER_NOTIFY         NotifyFunction
  )
{
  if ((NotifyFunction == NULL) && (mTimerNotifyFunction == NULL)) {
    return EFI_INVALID_PARAMETER;
  }

  if ((NotifyFunction != NULL) && (mTimerNotifyFunction != NULL)) {
    return EFI_ALREADY_STARTED;
  }

  mTimerNotifyFunction = NotifyFunction;

  return EFI_SUCCESS;
}

/**\r
  This function adjusts the period of timer interrupts to the value specified \r
  by TimerPeriod.  If the timer period is updated, then the selected timer \r
  period is stored in EFI_TIMER.TimerPeriod, and EFI_SUCCESS is returned.  If \r
  the timer hardware is not programmable, then EFI_UNSUPPORTED is returned.  \r
  If an error occurs while attempting to update the timer period, then the \r
  timer hardware will be put back in its state prior to this call, and \r
  EFI_DEVICE_ERROR is returned.  If TimerPeriod is 0, then the timer interrupt \r
  is disabled.  This is not the same as disabling the CPU's interrupts.  \r
  Instead, it must either turn off the timer hardware, or it must adjust the \r
  interrupt controller so that a CPU interrupt is not generated when the timer \r
  interrupt fires. \r
\r
  @param  This             The EFI_TIMER_ARCH_PROTOCOL instance.\r
  @param  TimerPeriod      The rate to program the timer interrupt in 100 nS units. If\r
                           the timer hardware is not programmable, then EFI_UNSUPPORTED is\r
                           returned. If the timer is programmable, then the timer period\r
                           will be rounded up to the nearest timer period that is supported\r
                           by the timer hardware. If TimerPeriod is set to 0, then the\r
                           timer interrupts will be disabled.\r
\r
  @retval EFI_SUCCESS           The timer period was changed.\r
  @retval EFI_UNSUPPORTED       The platform cannot change the period of the timer interrupt.\r
  @retval EFI_DEVICE_ERROR      The timer period could not be changed due to a device error.\r
\r
**/
EFI_STATUS
EFIAPI
TimerDriverSetTimerPeriod (
  IN EFI_TIMER_ARCH_PROTOCOL  *This,
  IN UINT64                   TimerPeriod
  )
{
  EFI_STATUS  Status;
  UINT64      TimerCount;
  INT32       LoadValue;
  
  if (TimerPeriod == 0) {
    // Turn off GPTIMER3
    MmioWrite32(TCLR, TCLR_ST_OFF);
    
    Status = gInterrupt->DisableInterruptSource(gInterrupt, gVector);    
  } else {  
    // Calculate required timer count
    TimerCount = DivU64x32(TimerPeriod * 100, PcdGet32(PcdEmbeddedFdPerformanceCounterPeriodInNanoseconds));

    // Set GPTIMER3 Load register
    LoadValue = (INT32) -TimerCount;
    MmioWrite32(TLDR, LoadValue);
    MmioWrite32(TCRR, LoadValue);

    // Enable Overflow interrupt
    MmioWrite32(TIER, TIER_TCAR_IT_DISABLE | TIER_OVF_IT_ENABLE | TIER_MAT_IT_DISABLE);

    // Turn on GPTIMER3, it will reload at overflow
    MmioWrite32(TCLR, TCLR_AR_AUTORELOAD | TCLR_ST_ON);

    Status = gInterrupt->EnableInterruptSource(gInterrupt, gVector);    
  }

  //
  // Save the new timer period
  //
  mTimerPeriod = TimerPeriod;
  return Status;
}


/**\r
  This function retrieves the period of timer interrupts in 100 ns units, \r
  returns that value in TimerPeriod, and returns EFI_SUCCESS.  If TimerPeriod \r
  is NULL, then EFI_INVALID_PARAMETER is returned.  If a TimerPeriod of 0 is \r
  returned, then the timer is currently disabled.\r
\r
  @param  This             The EFI_TIMER_ARCH_PROTOCOL instance.\r
  @param  TimerPeriod      A pointer to the timer period to retrieve in 100 ns units. If\r
                           0 is returned, then the timer is currently disabled.\r
\r
  @retval EFI_SUCCESS           The timer period was returned in TimerPeriod.\r
  @retval EFI_INVALID_PARAMETER TimerPeriod is NULL.\r
\r
**/
EFI_STATUS
EFIAPI
TimerDriverGetTimerPeriod (
  IN EFI_TIMER_ARCH_PROTOCOL   *This,
  OUT UINT64                   *TimerPeriod
  )
{
  if (TimerPeriod == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  *TimerPeriod = mTimerPeriod;
  return EFI_SUCCESS;
}

/**\r
  This function generates a soft timer interrupt. If the platform does not support soft \r
  timer interrupts, then EFI_UNSUPPORTED is returned. Otherwise, EFI_SUCCESS is returned. \r
  If a handler has been registered through the EFI_TIMER_ARCH_PROTOCOL.RegisterHandler() \r
  service, then a soft timer interrupt will be generated. If the timer interrupt is \r
  enabled when this service is called, then the registered handler will be invoked. The \r
  registered handler should not be able to distinguish a hardware-generated timer \r
  interrupt from a software-generated timer interrupt.\r
\r
  @param  This             The EFI_TIMER_ARCH_PROTOCOL instance.\r
\r
  @retval EFI_SUCCESS           The soft timer interrupt was generated.\r
  @retval EFI_UNSUPPORTED       The platform does not support the generation of soft timer interrupts.\r
\r
**/
EFI_STATUS
EFIAPI
TimerDriverGenerateSoftInterrupt (
  IN EFI_TIMER_ARCH_PROTOCOL  *This
  )
{
  return EFI_UNSUPPORTED;
}


EFI_STATUS
EFIAPI
TimerDriverRegisterPeriodicCallback (
  IN  TIMER_DEBUG_SUPPORT_PROTOCOL  *This,
  IN  EFI_PERIODIC_CALLBACK         PeriodicCallback
  )
{
  if ((PeriodicCallback == NULL) && (mTimerPeriodicCallback == NULL)) {
    return EFI_INVALID_PARAMETER;
  }

  if ((PeriodicCallback != NULL) && (mTimerPeriodicCallback != NULL)) {
    return EFI_ALREADY_STARTED;
  }

  mTimerPeriodicCallback = PeriodicCallback;

  return EFI_SUCCESS;
}


/**\r
  Interface stucture for the Timer Architectural Protocol.\r
\r
  @par Protocol Description:\r
  This protocol provides the services to initialize a periodic timer \r
  interrupt, and to register a handler that is called each time the timer\r
  interrupt fires.  It may also provide a service to adjust the rate of the\r
  periodic timer interrupt.  When a timer interrupt occurs, the handler is \r
  passed the amount of time that has passed since the previous timer \r
  interrupt.\r
\r
  @param RegisterHandler\r
  Registers a handler that will be called each time the \r
  timer interrupt fires.  TimerPeriod defines the minimum \r
  time between timer interrupts, so TimerPeriod will also \r
  be the minimum time between calls to the registered \r
  handler.\r
\r
  @param SetTimerPeriod\r
  Sets the period of the timer interrupt in 100 nS units.  \r
  This function is optional, and may return EFI_UNSUPPORTED.  \r
  If this function is supported, then the timer period will \r
  be rounded up to the nearest supported timer period.\r
\r
  @param GetTimerPeriod\r
  Retrieves the period of the timer interrupt in 100 nS units.\r
\r
  @param GenerateSoftInterrupt\r
  Generates a soft timer interrupt that simulates the firing of \r
  the timer interrupt. This service can be used to invoke the \r
  registered handler if the timer interrupt has been masked for \r
  a period of time.\r
\r
**/
EFI_TIMER_ARCH_PROTOCOL   gTimer = {
  TimerDriverRegisterHandler,
  TimerDriverSetTimerPeriod,
  TimerDriverGetTimerPeriod,
  TimerDriverGenerateSoftInterrupt
};

TIMER_DEBUG_SUPPORT_PROTOCOL  gTimerDebugSupport = {
  TimerDriverRegisterPeriodicCallback
};


/**\r
  Initialize the state information for the Timer Architectural Protocol and\r
  the Timer Debug support protocol that allows the debugger to break into a\r
  running program.\r
\r
  @param  ImageHandle   of the loaded driver\r
  @param  SystemTable   Pointer to the System Table\r
\r
  @retval EFI_SUCCESS           Protocol registered\r
  @retval EFI_OUT_OF_RESOURCES  Cannot allocate protocol data structure\r
  @retval EFI_DEVICE_ERROR      Hardware problems\r
\r
**/
EFI_STATUS
EFIAPI
TimerInitialize (
  IN EFI_HANDLE         ImageHandle,
  IN EFI_SYSTEM_TABLE   *SystemTable
  )
{
  EFI_HANDLE  Handle = NULL;
  EFI_STATUS  Status;
  UINT32      TimerBaseAddress;

  // Find the interrupt controller protocol.  ASSERT if not found.
  Status = gBS->LocateProtocol(&gHardwareInterruptProtocolGuid, NULL, (VOID **)&gInterrupt);
  ASSERT_EFI_ERROR (Status);

  // Set up the timer registers
  TimerBaseAddress = TimerBase(FixedPcdGet32(PcdBeagleArchTimer));
  TISR = TimerBaseAddress + GPTIMER_TISR;
  TCLR = TimerBaseAddress + GPTIMER_TCLR;
  TLDR = TimerBaseAddress + GPTIMER_TLDR;
  TCRR = TimerBaseAddress + GPTIMER_TCRR;
  TIER = TimerBaseAddress + GPTIMER_TIER;

  // Disable the timer
  Status = TimerDriverSetTimerPeriod(&gTimer, 0);
  ASSERT_EFI_ERROR (Status);

  // Install interrupt handler
  gVector = InterruptVectorForTimer(FixedPcdGet32(PcdBeagleArchTimer));
  Status = gInterrupt->RegisterInterruptSource(gInterrupt, gVector, TimerInterruptHandler);
  ASSERT_EFI_ERROR (Status);

  // Set up default timer
  Status = TimerDriverSetTimerPeriod(&gTimer, FixedPcdGet32(PcdTimerPeriod));
  ASSERT_EFI_ERROR (Status);

  // Install the Timer Architectural Protocol onto a new handle
  Status = gBS->InstallMultipleProtocolInterfaces(&Handle,
                                                  &gEfiTimerArchProtocolGuid,      &gTimer,
                                                  &gTimerDebugSupportProtocolGuid, &gTimerDebugSupport,
                                                  NULL);
  ASSERT_EFI_ERROR(Status);

  return Status;
}
Commit	Line	Data
	1	/** @file
	2	Template for Timer Architecture Protocol driver of the ARM flavor
	3
	4	Copyright (c) 2008-2009, Apple Inc. All rights reserved.
	5
	6	All rights reserved. This program and the accompanying materials
	7	are licensed and made available under the terms and conditions of the BSD License
	8	which accompanies this distribution. The full text of the license may be found at
	9	http://opensource.org/licenses/bsd-license.php
	10
	11	THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
	12	WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
	13
	14	**/
	15
	16
	17	#include <PiDxe.h>
	18
	19	#include <Library/BaseLib.h>
	20	#include <Library/DebugLib.h>
	21	#include <Library/BaseMemoryLib.h>
	22	#include <Library/UefiBootServicesTableLib.h>
	23	#include <Library/UefiLib.h>
	24	#include <Library/PcdLib.h>
	25	#include <Library/IoLib.h>
	26	#include <Library/OmapLib.h>
	27
	28	#include <Protocol/Timer.h>
	29	#include <Protocol/HardwareInterrupt.h>
	30	#include <Protocol/TimerDebugSupport.h>
	31
	32	#include <Omap3530/Omap3530.h>
	33
	34
	35	// The notification function to call on every timer interrupt.
	36	volatile EFI_TIMER_NOTIFY mTimerNotifyFunction = (EFI_TIMER_NOTIFY)NULL;
	37	volatile EFI_PERIODIC_CALLBACK mTimerPeriodicCallback = (EFI_PERIODIC_CALLBACK)NULL;
	38
	39
	40	// The current period of the timer interrupt
	41	volatile UINT64 mTimerPeriod = 0;
	42
	43	// Cached copy of the Hardware Interrupt protocol instance
	44	EFI_HARDWARE_INTERRUPT_PROTOCOL *gInterrupt = NULL;
	45
	46	// Cached registers
	47	volatile UINT32 TISR;
	48	volatile UINT32 TCLR;
	49	volatile UINT32 TLDR;
	50	volatile UINT32 TCRR;
	51	volatile UINT32 TIER;
	52
	53	// Cached interrupt vector
	54	volatile UINTN gVector;
	55
	56
	57	/**\r
	58	C Interrupt Handler calledin the interrupt context when Source interrupt is active.\r
	59	\r
	60	@param Source Source of the interrupt. Hardware routing off a specific platform defines\r
	61	what source means.\r
	62	@param SystemContext Pointer to system register context. Mostly used by debuggers and will\r
	63	update the system context after the return from the interrupt if \r
	64	modified. Don't change these values unless you know what you are doing\r
	65	\r
	66	**/
	67	VOID
	68	EFIAPI
	69	TimerInterruptHandler (
	70	IN HARDWARE_INTERRUPT_SOURCE Source,
	71	IN EFI_SYSTEM_CONTEXT SystemContext
	72	)
	73	{
	74	EFI_TPL OriginalTPL;\r
	75	\r
	76	//\r
	77	// DXE core uses this callback for the EFI timer tick. The DXE core uses locks \r
	78	// that raise to TPL_HIGH and then restore back to current level. Thus we need\r
	79	// to make sure TPL level is set to TPL_HIGH while we are handling the timer tick. \r
	80	//\r
	81	OriginalTPL = gBS->RaiseTPL (TPL_HIGH_LEVEL);\r
	82
	83	if (mTimerPeriodicCallback) {
	84	mTimerPeriodicCallback(SystemContext);
	85	}
	86
	87	if (mTimerNotifyFunction) {
	88	mTimerNotifyFunction(mTimerPeriod);
	89	}
	90
	91	// Clear all timer interrupts
	92	MmioWrite32(TISR, TISR_CLEAR_ALL);
	93
	94	// Poll interrupt status bits to ensure clearing
	95	while ((MmioRead32(TISR) & TISR_ALL_INTERRUPT_MASK) != TISR_NO_INTERRUPTS_PENDING);
	96
	97	gBS->RestoreTPL (OriginalTPL);
	98	}
	99
	100	/**\r
	101	This function registers the handler NotifyFunction so it is called every time \r
	102	the timer interrupt fires. It also passes the amount of time since the last \r
	103	handler call to the NotifyFunction. If NotifyFunction is NULL, then the \r
	104	handler is unregistered. If the handler is registered, then EFI_SUCCESS is \r
	105	returned. If the CPU does not support registering a timer interrupt handler, \r
	106	then EFI_UNSUPPORTED is returned. If an attempt is made to register a handler \r
	107	when a handler is already registered, then EFI_ALREADY_STARTED is returned. \r
	108	If an attempt is made to unregister a handler when a handler is not registered, \r
	109	then EFI_INVALID_PARAMETER is returned. If an error occurs attempting to \r
	110	register the NotifyFunction with the timer interrupt, then EFI_DEVICE_ERROR \r
	111	is returned.\r
	112	\r
	113	@param This The EFI_TIMER_ARCH_PROTOCOL instance.\r
	114	@param NotifyFunction The function to call when a timer interrupt fires. This\r
	115	function executes at TPL_HIGH_LEVEL. The DXE Core will\r
	116	register a handler for the timer interrupt, so it can know\r
	117	how much time has passed. This information is used to\r
	118	signal timer based events. NULL will unregister the handler.\r
	119	\r
	120	@retval EFI_SUCCESS The timer handler was registered.\r
	121	@retval EFI_UNSUPPORTED The platform does not support timer interrupts.\r
	122	@retval EFI_ALREADY_STARTED NotifyFunction is not NULL, and a handler is already\r
	123	registered.\r
	124	@retval EFI_INVALID_PARAMETER NotifyFunction is NULL, and a handler was not\r
	125	previously registered.\r
	126	@retval EFI_DEVICE_ERROR The timer handler could not be registered.\r
	127	\r
	128	**/\r
	129	EFI_STATUS
	130	EFIAPI
	131	TimerDriverRegisterHandler (
	132	IN EFI_TIMER_ARCH_PROTOCOL *This,
	133	IN EFI_TIMER_NOTIFY NotifyFunction
	134	)
	135	{
	136	if ((NotifyFunction == NULL) && (mTimerNotifyFunction == NULL)) {
	137	return EFI_INVALID_PARAMETER;
	138	}
	139
	140	if ((NotifyFunction != NULL) && (mTimerNotifyFunction != NULL)) {
	141	return EFI_ALREADY_STARTED;
	142	}
	143
	144	mTimerNotifyFunction = NotifyFunction;
	145
	146	return EFI_SUCCESS;
	147	}
	148
	149	/**\r
	150	This function adjusts the period of timer interrupts to the value specified \r
	151	by TimerPeriod. If the timer period is updated, then the selected timer \r
	152	period is stored in EFI_TIMER.TimerPeriod, and EFI_SUCCESS is returned. If \r
	153	the timer hardware is not programmable, then EFI_UNSUPPORTED is returned. \r
	154	If an error occurs while attempting to update the timer period, then the \r
	155	timer hardware will be put back in its state prior to this call, and \r
	156	EFI_DEVICE_ERROR is returned. If TimerPeriod is 0, then the timer interrupt \r
	157	is disabled. This is not the same as disabling the CPU's interrupts. \r
	158	Instead, it must either turn off the timer hardware, or it must adjust the \r
	159	interrupt controller so that a CPU interrupt is not generated when the timer \r
	160	interrupt fires. \r
	161	\r
	162	@param This The EFI_TIMER_ARCH_PROTOCOL instance.\r
	163	@param TimerPeriod The rate to program the timer interrupt in 100 nS units. If\r
	164	the timer hardware is not programmable, then EFI_UNSUPPORTED is\r
	165	returned. If the timer is programmable, then the timer period\r
	166	will be rounded up to the nearest timer period that is supported\r
	167	by the timer hardware. If TimerPeriod is set to 0, then the\r
	168	timer interrupts will be disabled.\r
	169	\r
	170	@retval EFI_SUCCESS The timer period was changed.\r
	171	@retval EFI_UNSUPPORTED The platform cannot change the period of the timer interrupt.\r
	172	@retval EFI_DEVICE_ERROR The timer period could not be changed due to a device error.\r
	173	\r
	174	**/
	175	EFI_STATUS
	176	EFIAPI
	177	TimerDriverSetTimerPeriod (
	178	IN EFI_TIMER_ARCH_PROTOCOL *This,
	179	IN UINT64 TimerPeriod
	180	)
	181	{
	182	EFI_STATUS Status;
	183	UINT64 TimerCount;
	184	INT32 LoadValue;
	185
	186	if (TimerPeriod == 0) {
	187	// Turn off GPTIMER3
	188	MmioWrite32(TCLR, TCLR_ST_OFF);
	189
	190	Status = gInterrupt->DisableInterruptSource(gInterrupt, gVector);
	191	} else {
	192	// Calculate required timer count
	193	TimerCount = DivU64x32(TimerPeriod * 100, PcdGet32(PcdEmbeddedFdPerformanceCounterPeriodInNanoseconds));
	194
	195	// Set GPTIMER3 Load register
	196	LoadValue = (INT32) -TimerCount;
	197	MmioWrite32(TLDR, LoadValue);
	198	MmioWrite32(TCRR, LoadValue);
	199
	200	// Enable Overflow interrupt
	201	MmioWrite32(TIER, TIER_TCAR_IT_DISABLE \| TIER_OVF_IT_ENABLE \| TIER_MAT_IT_DISABLE);
	202
	203	// Turn on GPTIMER3, it will reload at overflow
	204	MmioWrite32(TCLR, TCLR_AR_AUTORELOAD \| TCLR_ST_ON);
	205
	206	Status = gInterrupt->EnableInterruptSource(gInterrupt, gVector);
	207	}
	208
	209	//
	210	// Save the new timer period
	211	//
	212	mTimerPeriod = TimerPeriod;
	213	return Status;
	214	}
	215
	216
	217	/**\r
	218	This function retrieves the period of timer interrupts in 100 ns units, \r
	219	returns that value in TimerPeriod, and returns EFI_SUCCESS. If TimerPeriod \r
	220	is NULL, then EFI_INVALID_PARAMETER is returned. If a TimerPeriod of 0 is \r
	221	returned, then the timer is currently disabled.\r
	222	\r
	223	@param This The EFI_TIMER_ARCH_PROTOCOL instance.\r
	224	@param TimerPeriod A pointer to the timer period to retrieve in 100 ns units. If\r
	225	0 is returned, then the timer is currently disabled.\r
	226	\r
	227	@retval EFI_SUCCESS The timer period was returned in TimerPeriod.\r
	228	@retval EFI_INVALID_PARAMETER TimerPeriod is NULL.\r
	229	\r
	230	**/
	231	EFI_STATUS
	232	EFIAPI
	233	TimerDriverGetTimerPeriod (
	234	IN EFI_TIMER_ARCH_PROTOCOL *This,
	235	OUT UINT64 *TimerPeriod
	236	)
	237	{
	238	if (TimerPeriod == NULL) {
	239	return EFI_INVALID_PARAMETER;
	240	}
	241
	242	*TimerPeriod = mTimerPeriod;
	243	return EFI_SUCCESS;
	244	}
	245
	246	/**\r
	247	This function generates a soft timer interrupt. If the platform does not support soft \r
	248	timer interrupts, then EFI_UNSUPPORTED is returned. Otherwise, EFI_SUCCESS is returned. \r
	249	If a handler has been registered through the EFI_TIMER_ARCH_PROTOCOL.RegisterHandler() \r
	250	service, then a soft timer interrupt will be generated. If the timer interrupt is \r
	251	enabled when this service is called, then the registered handler will be invoked. The \r
	252	registered handler should not be able to distinguish a hardware-generated timer \r
	253	interrupt from a software-generated timer interrupt.\r
	254	\r
	255	@param This The EFI_TIMER_ARCH_PROTOCOL instance.\r
	256	\r
	257	@retval EFI_SUCCESS The soft timer interrupt was generated.\r
	258	@retval EFI_UNSUPPORTED The platform does not support the generation of soft timer interrupts.\r
	259	\r
	260	**/
	261	EFI_STATUS
	262	EFIAPI
	263	TimerDriverGenerateSoftInterrupt (
	264	IN EFI_TIMER_ARCH_PROTOCOL *This
	265	)
	266	{
	267	return EFI_UNSUPPORTED;
	268	}
	269
	270
	271	EFI_STATUS
	272	EFIAPI
	273	TimerDriverRegisterPeriodicCallback (
	274	IN TIMER_DEBUG_SUPPORT_PROTOCOL *This,
	275	IN EFI_PERIODIC_CALLBACK PeriodicCallback
	276	)
	277	{
	278	if ((PeriodicCallback == NULL) && (mTimerPeriodicCallback == NULL)) {
	279	return EFI_INVALID_PARAMETER;
	280	}
	281
	282	if ((PeriodicCallback != NULL) && (mTimerPeriodicCallback != NULL)) {
	283	return EFI_ALREADY_STARTED;
	284	}
	285
	286	mTimerPeriodicCallback = PeriodicCallback;
	287
	288	return EFI_SUCCESS;
	289	}
	290
	291
	292	/**\r
	293	Interface stucture for the Timer Architectural Protocol.\r
	294	\r
	295	@par Protocol Description:\r
	296	This protocol provides the services to initialize a periodic timer \r
	297	interrupt, and to register a handler that is called each time the timer\r
	298	interrupt fires. It may also provide a service to adjust the rate of the\r
	299	periodic timer interrupt. When a timer interrupt occurs, the handler is \r
	300	passed the amount of time that has passed since the previous timer \r
	301	interrupt.\r
	302	\r
	303	@param RegisterHandler\r
	304	Registers a handler that will be called each time the \r
	305	timer interrupt fires. TimerPeriod defines the minimum \r
	306	time between timer interrupts, so TimerPeriod will also \r
	307	be the minimum time between calls to the registered \r
	308	handler.\r
	309	\r
	310	@param SetTimerPeriod\r
	311	Sets the period of the timer interrupt in 100 nS units. \r
	312	This function is optional, and may return EFI_UNSUPPORTED. \r
	313	If this function is supported, then the timer period will \r
	314	be rounded up to the nearest supported timer period.\r
	315	\r
	316	@param GetTimerPeriod\r
	317	Retrieves the period of the timer interrupt in 100 nS units.\r
	318	\r
	319	@param GenerateSoftInterrupt\r
	320	Generates a soft timer interrupt that simulates the firing of \r
	321	the timer interrupt. This service can be used to invoke the \r
	322	registered handler if the timer interrupt has been masked for \r
	323	a period of time.\r
	324	\r
	325	**/
	326	EFI_TIMER_ARCH_PROTOCOL gTimer = {
	327	TimerDriverRegisterHandler,
	328	TimerDriverSetTimerPeriod,
	329	TimerDriverGetTimerPeriod,
	330	TimerDriverGenerateSoftInterrupt
	331	};
	332
	333	TIMER_DEBUG_SUPPORT_PROTOCOL gTimerDebugSupport = {
	334	TimerDriverRegisterPeriodicCallback
	335	};
	336
	337
	338	/**\r
	339	Initialize the state information for the Timer Architectural Protocol and\r
	340	the Timer Debug support protocol that allows the debugger to break into a\r
	341	running program.\r
	342	\r
	343	@param ImageHandle of the loaded driver\r
	344	@param SystemTable Pointer to the System Table\r
	345	\r
	346	@retval EFI_SUCCESS Protocol registered\r
	347	@retval EFI_OUT_OF_RESOURCES Cannot allocate protocol data structure\r
	348	@retval EFI_DEVICE_ERROR Hardware problems\r
	349	\r
	350	**/
	351	EFI_STATUS
	352	EFIAPI
	353	TimerInitialize (
	354	IN EFI_HANDLE ImageHandle,
	355	IN EFI_SYSTEM_TABLE *SystemTable
	356	)
	357	{
	358	EFI_HANDLE Handle = NULL;
	359	EFI_STATUS Status;
	360	UINT32 TimerBaseAddress;
	361
	362	// Find the interrupt controller protocol. ASSERT if not found.
	363	Status = gBS->LocateProtocol(&gHardwareInterruptProtocolGuid, NULL, (VOID **)&gInterrupt);
	364	ASSERT_EFI_ERROR (Status);
	365
	366	// Set up the timer registers
	367	TimerBaseAddress = TimerBase(FixedPcdGet32(PcdBeagleArchTimer));
	368	TISR = TimerBaseAddress + GPTIMER_TISR;
	369	TCLR = TimerBaseAddress + GPTIMER_TCLR;
	370	TLDR = TimerBaseAddress + GPTIMER_TLDR;
	371	TCRR = TimerBaseAddress + GPTIMER_TCRR;
	372	TIER = TimerBaseAddress + GPTIMER_TIER;
	373
	374	// Disable the timer
	375	Status = TimerDriverSetTimerPeriod(&gTimer, 0);
	376	ASSERT_EFI_ERROR (Status);
	377
	378	// Install interrupt handler
	379	gVector = InterruptVectorForTimer(FixedPcdGet32(PcdBeagleArchTimer));
	380	Status = gInterrupt->RegisterInterruptSource(gInterrupt, gVector, TimerInterruptHandler);
	381	ASSERT_EFI_ERROR (Status);
	382
	383	// Set up default timer
	384	Status = TimerDriverSetTimerPeriod(&gTimer, FixedPcdGet32(PcdTimerPeriod));
	385	ASSERT_EFI_ERROR (Status);
	386
	387	// Install the Timer Architectural Protocol onto a new handle
	388	Status = gBS->InstallMultipleProtocolInterfaces(&Handle,
	389	&gEfiTimerArchProtocolGuid, &gTimer,
	390	&gTimerDebugSupportProtocolGuid, &gTimerDebugSupport,
	391	NULL);
	392	ASSERT_EFI_ERROR(Status);
	393
	394	return Status;
	395	}
	396