[mirror_edk2.git] / OvmfPkg / LocalApicTimerDxe / LocalApicTimerDxe.c

/** @file\r
  Timer Architectural Protocol as defined in the DXE CIS\r
\r
Copyright (c) 2005 - 2018, Intel Corporation. All rights reserved.<BR>\r
Copyright (c) 2019, Citrix Systems, Inc.\r
\r
SPDX-License-Identifier: BSD-2-Clause-Patent\r
\r
**/\r
\r
#include <Library/NestedInterruptTplLib.h>\r
\r
#include "LocalApicTimerDxe.h"\r
\r
//\r
// The handle onto which the Timer Architectural Protocol will be installed\r
//\r
EFI_HANDLE  mTimerHandle = NULL;\r
\r
//\r
// The Timer Architectural Protocol that this driver produces\r
//\r
EFI_TIMER_ARCH_PROTOCOL  mTimer = {\r
  TimerDriverRegisterHandler,\r
  TimerDriverSetTimerPeriod,\r
  TimerDriverGetTimerPeriod,\r
  TimerDriverGenerateSoftInterrupt\r
};\r
\r
//\r
// Pointer to the CPU Architectural Protocol instance\r
//\r
EFI_CPU_ARCH_PROTOCOL  *mCpu;\r
\r
//\r
// The notification function to call on every timer interrupt.\r
// A bug in the compiler prevents us from initializing this here.\r
//\r
EFI_TIMER_NOTIFY  mTimerNotifyFunction;\r
\r
//\r
// The current period of the timer interrupt\r
//\r
volatile UINT64  mTimerPeriod = 0;\r
\r
//\r
// Worker Functions\r
//\r
\r
/**\r
  Interrupt Handler.\r
\r
  @param InterruptType    The type of interrupt that occurred\r
  @param SystemContext    A pointer to the system context when the interrupt occurred\r
**/\r
VOID\r
EFIAPI\r
TimerInterruptHandler (\r
  IN EFI_EXCEPTION_TYPE  InterruptType,\r
  IN EFI_SYSTEM_CONTEXT  SystemContext\r
  )\r
{\r
  STATIC NESTED_INTERRUPT_STATE  NestedInterruptState;\r
  EFI_TPL                        OriginalTPL;\r
\r
  OriginalTPL = NestedInterruptRaiseTPL ();\r
\r
  SendApicEoi ();\r
\r
  if (mTimerNotifyFunction != NULL) {\r
    //\r
    // @bug : This does not handle missed timer interrupts\r
    //\r
    mTimerNotifyFunction (mTimerPeriod);\r
  }\r
\r
  NestedInterruptRestoreTPL (OriginalTPL, SystemContext, &NestedInterruptState);\r
}\r
\r
/**\r
\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
\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\r
EFIAPI\r
TimerDriverRegisterHandler (\r
  IN EFI_TIMER_ARCH_PROTOCOL  *This,\r
  IN EFI_TIMER_NOTIFY         NotifyFunction\r
  )\r
{\r
  //\r
  // Check for invalid parameters\r
  //\r
  if ((NotifyFunction == NULL) && (mTimerNotifyFunction == NULL)) {\r
    return EFI_INVALID_PARAMETER;\r
  }\r
\r
  if ((NotifyFunction != NULL) && (mTimerNotifyFunction != NULL)) {\r
    return EFI_ALREADY_STARTED;\r
  }\r
\r
  mTimerNotifyFunction = NotifyFunction;\r
\r
  return EFI_SUCCESS;\r
}\r
\r
/**\r
\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
\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
**/\r
EFI_STATUS\r
EFIAPI\r
TimerDriverSetTimerPeriod (\r
  IN EFI_TIMER_ARCH_PROTOCOL  *This,\r
  IN UINT64                   TimerPeriod\r
  )\r
{\r
  UINT64  TimerCount;\r
  UINT32  TimerFrequency;\r
  UINT32  DivideValue = 1;\r
\r
  if (TimerPeriod == 0) {\r
    //\r
    // Disable timer interrupt for a TimerPeriod of 0\r
    //\r
    DisableApicTimerInterrupt ();\r
  } else {\r
    TimerFrequency = PcdGet32 (PcdFSBClock) / (UINT32)DivideValue;\r
\r
    //\r
    // Convert TimerPeriod into local APIC counts\r
    //\r
    // TimerPeriod is in 100ns\r
    // TimerPeriod/10000000 will be in seconds.\r
    TimerCount = DivU64x32 (\r
                   MultU64x32 (TimerPeriod, TimerFrequency),\r
                   10000000\r
                   );\r
\r
    // Check for overflow\r
    if (TimerCount > MAX_UINT32) {\r
      TimerCount = MAX_UINT32;\r
      /* TimerPeriod = (MAX_UINT32 / TimerFrequency) * 10000000; */\r
      TimerPeriod = 429496730;\r
    }\r
\r
    //\r
    // Program the timer with the new count value\r
    //\r
    InitializeApicTimer (DivideValue, (UINT32)TimerCount, TRUE, LOCAL_APIC_TIMER_VECTOR);\r
\r
    //\r
    // Enable timer interrupt\r
    //\r
    EnableApicTimerInterrupt ();\r
  }\r
\r
  //\r
  // Save the new timer period\r
  //\r
  mTimerPeriod = TimerPeriod;\r
\r
  return EFI_SUCCESS;\r
}\r
\r
/**\r
\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
\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
**/\r
EFI_STATUS\r
EFIAPI\r
TimerDriverGetTimerPeriod (\r
  IN EFI_TIMER_ARCH_PROTOCOL  *This,\r
  OUT UINT64                  *TimerPeriod\r
  )\r
{\r
  if (TimerPeriod == NULL) {\r
    return EFI_INVALID_PARAMETER;\r
  }\r
\r
  *TimerPeriod = mTimerPeriod;\r
\r
  return EFI_SUCCESS;\r
}\r
\r
/**\r
\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
\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
**/\r
EFI_STATUS\r
EFIAPI\r
TimerDriverGenerateSoftInterrupt (\r
  IN EFI_TIMER_ARCH_PROTOCOL  *This\r
  )\r
{\r
  EFI_TPL  OriginalTPL;\r
\r
  if (GetApicTimerInterruptState ()) {\r
    //\r
    // Invoke the registered handler\r
    //\r
    OriginalTPL = gBS->RaiseTPL (TPL_HIGH_LEVEL);\r
\r
    if (mTimerNotifyFunction != NULL) {\r
      //\r
      // @bug : This does not handle missed timer interrupts\r
      //\r
      mTimerNotifyFunction (mTimerPeriod);\r
    }\r
\r
    gBS->RestoreTPL (OriginalTPL);\r
  } else {\r
    return EFI_UNSUPPORTED;\r
  }\r
\r
  return EFI_SUCCESS;\r
}\r
\r
/**\r
  Initialize the Timer Architectural Protocol driver\r
\r
  @param ImageHandle     ImageHandle of the loaded driver\r
  @param SystemTable     Pointer to the System Table\r
\r
  @retval EFI_SUCCESS            Timer Architectural Protocol created\r
  @retval EFI_OUT_OF_RESOURCES   Not enough resources available to initialize driver.\r
  @retval EFI_DEVICE_ERROR       A device error occurred attempting to initialize the driver.\r
\r
**/\r
EFI_STATUS\r
EFIAPI\r
TimerDriverInitialize (\r
  IN EFI_HANDLE        ImageHandle,\r
  IN EFI_SYSTEM_TABLE  *SystemTable\r
  )\r
{\r
  EFI_STATUS  Status;\r
\r
  //\r
  // Initialize the pointer to our notify function.\r
  //\r
  mTimerNotifyFunction = NULL;\r
\r
  //\r
  // Make sure the Timer Architectural Protocol is not already installed in the system\r
  //\r
  ASSERT_PROTOCOL_ALREADY_INSTALLED (NULL, &gEfiTimerArchProtocolGuid);\r
\r
  //\r
  // Find the CPU architectural protocol.\r
  //\r
  Status = gBS->LocateProtocol (&gEfiCpuArchProtocolGuid, NULL, (VOID **)&mCpu);\r
  ASSERT_EFI_ERROR (Status);\r
\r
  //\r
  // Force the timer to be disabled\r
  //\r
  Status = TimerDriverSetTimerPeriod (&mTimer, 0);\r
  ASSERT_EFI_ERROR (Status);\r
\r
  //\r
  // Install interrupt handler for Local APIC Timer\r
  //\r
  Status = mCpu->RegisterInterruptHandler (\r
                   mCpu,\r
                   LOCAL_APIC_TIMER_VECTOR,\r
                   TimerInterruptHandler\r
                   );\r
  ASSERT_EFI_ERROR (Status);\r
\r
  //\r
  // Force the timer to be enabled at its default period\r
  //\r
  Status = TimerDriverSetTimerPeriod (&mTimer, DEFAULT_TIMER_TICK_DURATION);\r
  ASSERT_EFI_ERROR (Status);\r
\r
  //\r
  // Install the Timer Architectural Protocol onto a new handle\r
  //\r
  Status = gBS->InstallMultipleProtocolInterfaces (\r
                  &mTimerHandle,\r
                  &gEfiTimerArchProtocolGuid,\r
                  &mTimer,\r
                  NULL\r
                  );\r
  ASSERT_EFI_ERROR (Status);\r
\r
  return Status;\r
}\r
Commit	Line	Data
d668c8bc AP	1	/** @file\r
	2	Timer Architectural Protocol as defined in the DXE CIS\r
	3	\r
	4	Copyright (c) 2005 - 2018, Intel Corporation. All rights reserved.<BR>\r
	5	Copyright (c) 2019, Citrix Systems, Inc.\r
	6	\r
	7	SPDX-License-Identifier: BSD-2-Clause-Patent\r
	8	\r
	9	**/\r
	10	\r
a086f4a6 MB	11	#include <Library/NestedInterruptTplLib.h>\r
a086f4a6 MB	12	\r
c2e7be40	13	#include "LocalApicTimerDxe.h"\r
d668c8bc AP	14	\r
	15	//\r
	16	// The handle onto which the Timer Architectural Protocol will be installed\r
	17	//\r
ac0a286f	18	EFI_HANDLE mTimerHandle = NULL;\r
d668c8bc AP	19	\r
	20	//\r
	21	// The Timer Architectural Protocol that this driver produces\r
	22	//\r
ac0a286f	23	EFI_TIMER_ARCH_PROTOCOL mTimer = {\r
d668c8bc AP	24	TimerDriverRegisterHandler,\r
	25	TimerDriverSetTimerPeriod,\r
	26	TimerDriverGetTimerPeriod,\r
	27	TimerDriverGenerateSoftInterrupt\r
	28	};\r
	29	\r
	30	//\r
	31	// Pointer to the CPU Architectural Protocol instance\r
	32	//\r
ac0a286f	33	EFI_CPU_ARCH_PROTOCOL *mCpu;\r
d668c8bc AP	34	\r
	35	//\r
	36	// The notification function to call on every timer interrupt.\r
	37	// A bug in the compiler prevents us from initializing this here.\r
	38	//\r
ac0a286f	39	EFI_TIMER_NOTIFY mTimerNotifyFunction;\r
d668c8bc AP	40	\r
	41	//\r
	42	// The current period of the timer interrupt\r
	43	//\r
ac0a286f	44	volatile UINT64 mTimerPeriod = 0;\r
d668c8bc AP	45	\r
	46	//\r
	47	// Worker Functions\r
	48	//\r
ac0a286f	49	\r
d668c8bc AP	50	/**\r
	51	Interrupt Handler.\r
	52	\r
	53	@param InterruptType The type of interrupt that occurred\r
	54	@param SystemContext A pointer to the system context when the interrupt occurred\r
	55	**/\r
	56	VOID\r
	57	EFIAPI\r
	58	TimerInterruptHandler (\r
ac0a286f MK	59	IN EFI_EXCEPTION_TYPE InterruptType,\r
ac0a286f MK	60	IN EFI_SYSTEM_CONTEXT SystemContext\r
d668c8bc AP	61	)\r
d668c8bc AP	62	{\r
a086f4a6 MB	63	STATIC NESTED_INTERRUPT_STATE NestedInterruptState;\r
a086f4a6 MB	64	EFI_TPL OriginalTPL;\r
d668c8bc	65	\r
a086f4a6	66	OriginalTPL = NestedInterruptRaiseTPL ();\r
d668c8bc	67	\r
9bf473da MB	68	SendApicEoi ();\r
9bf473da MB	69	\r
d668c8bc AP	70	if (mTimerNotifyFunction != NULL) {\r
	71	//\r
	72	// @bug : This does not handle missed timer interrupts\r
	73	//\r
	74	mTimerNotifyFunction (mTimerPeriod);\r
	75	}\r
	76	\r
a086f4a6	77	NestedInterruptRestoreTPL (OriginalTPL, SystemContext, &NestedInterruptState);\r
d668c8bc AP	78	}\r
	79	\r
	80	/**\r
	81	\r
	82	This function registers the handler NotifyFunction so it is called every time\r
	83	the timer interrupt fires. It also passes the amount of time since the last\r
	84	handler call to the NotifyFunction. If NotifyFunction is NULL, then the\r
	85	handler is unregistered. If the handler is registered, then EFI_SUCCESS is\r
	86	returned. If the CPU does not support registering a timer interrupt handler,\r
	87	then EFI_UNSUPPORTED is returned. If an attempt is made to register a handler\r
	88	when a handler is already registered, then EFI_ALREADY_STARTED is returned.\r
	89	If an attempt is made to unregister a handler when a handler is not registered,\r
	90	then EFI_INVALID_PARAMETER is returned. If an error occurs attempting to\r
	91	register the NotifyFunction with the timer interrupt, then EFI_DEVICE_ERROR\r
	92	is returned.\r
	93	\r
	94	\r
	95	@param This The EFI_TIMER_ARCH_PROTOCOL instance.\r
	96	@param NotifyFunction The function to call when a timer interrupt fires. This\r
	97	function executes at TPL_HIGH_LEVEL. The DXE Core will\r
	98	register a handler for the timer interrupt, so it can know\r
	99	how much time has passed. This information is used to\r
	100	signal timer based events. NULL will unregister the handler.\r
	101	\r
	102	@retval EFI_SUCCESS The timer handler was registered.\r
	103	@retval EFI_UNSUPPORTED The platform does not support timer interrupts.\r
	104	@retval EFI_ALREADY_STARTED NotifyFunction is not NULL, and a handler is already\r
	105	registered.\r
	106	@retval EFI_INVALID_PARAMETER NotifyFunction is NULL, and a handler was not\r
	107	previously registered.\r
	108	@retval EFI_DEVICE_ERROR The timer handler could not be registered.\r
	109	\r
	110	**/\r
	111	EFI_STATUS\r
	112	EFIAPI\r
	113	TimerDriverRegisterHandler (\r
	114	IN EFI_TIMER_ARCH_PROTOCOL *This,\r
	115	IN EFI_TIMER_NOTIFY NotifyFunction\r
	116	)\r
	117	{\r
	118	//\r
	119	// Check for invalid parameters\r
	120	//\r
ac0a286f	121	if ((NotifyFunction == NULL) && (mTimerNotifyFunction == NULL)) {\r
d668c8bc AP	122	return EFI_INVALID_PARAMETER;\r
	123	}\r
	124	\r
ac0a286f	125	if ((NotifyFunction != NULL) && (mTimerNotifyFunction != NULL)) {\r
d668c8bc AP	126	return EFI_ALREADY_STARTED;\r
	127	}\r
	128	\r
	129	mTimerNotifyFunction = NotifyFunction;\r
	130	\r
	131	return EFI_SUCCESS;\r
	132	}\r
	133	\r
	134	/**\r
	135	\r
	136	This function adjusts the period of timer interrupts to the value specified\r
	137	by TimerPeriod. If the timer period is updated, then the selected timer\r
	138	period is stored in EFI_TIMER.TimerPeriod, and EFI_SUCCESS is returned. If\r
	139	the timer hardware is not programmable, then EFI_UNSUPPORTED is returned.\r
	140	If an error occurs while attempting to update the timer period, then the\r
	141	timer hardware will be put back in its state prior to this call, and\r
	142	EFI_DEVICE_ERROR is returned. If TimerPeriod is 0, then the timer interrupt\r
	143	is disabled. This is not the same as disabling the CPU's interrupts.\r
	144	Instead, it must either turn off the timer hardware, or it must adjust the\r
	145	interrupt controller so that a CPU interrupt is not generated when the timer\r
	146	interrupt fires.\r
	147	\r
	148	\r
	149	@param This The EFI_TIMER_ARCH_PROTOCOL instance.\r
	150	@param TimerPeriod The rate to program the timer interrupt in 100 nS units. If\r
	151	the timer hardware is not programmable, then EFI_UNSUPPORTED is\r
	152	returned. If the timer is programmable, then the timer period\r
	153	will be rounded up to the nearest timer period that is supported\r
	154	by the timer hardware. If TimerPeriod is set to 0, then the\r
	155	timer interrupts will be disabled.\r
	156	\r
	157	@retval EFI_SUCCESS The timer period was changed.\r
	158	@retval EFI_UNSUPPORTED The platform cannot change the period of the timer interrupt.\r
	159	@retval EFI_DEVICE_ERROR The timer period could not be changed due to a device error.\r
	160	\r
	161	**/\r
	162	EFI_STATUS\r
	163	EFIAPI\r
	164	TimerDriverSetTimerPeriod (\r
	165	IN EFI_TIMER_ARCH_PROTOCOL *This,\r
	166	IN UINT64 TimerPeriod\r
	167	)\r
	168	{\r
	169	UINT64 TimerCount;\r
	170	UINT32 TimerFrequency;\r
a9255967	171	UINT32 DivideValue = 1;\r
d668c8bc AP	172	\r
	173	if (TimerPeriod == 0) {\r
	174	//\r
	175	// Disable timer interrupt for a TimerPeriod of 0\r
	176	//\r
ac0a286f	177	DisableApicTimerInterrupt ();\r
d668c8bc	178	} else {\r
c37cbc03	179	TimerFrequency = PcdGet32 (PcdFSBClock) / (UINT32)DivideValue;\r
d668c8bc AP	180	\r
	181	//\r
	182	// Convert TimerPeriod into local APIC counts\r
	183	//\r
	184	// TimerPeriod is in 100ns\r
	185	// TimerPeriod/10000000 will be in seconds.\r
ac0a286f MK	186	TimerCount = DivU64x32 (\r
	187	MultU64x32 (TimerPeriod, TimerFrequency),\r
	188	10000000\r
	189	);\r
d668c8bc AP	190	\r
	191	// Check for overflow\r
	192	if (TimerCount > MAX_UINT32) {\r
	193	TimerCount = MAX_UINT32;\r
	194	/* TimerPeriod = (MAX_UINT32 / TimerFrequency) * 10000000; */\r
	195	TimerPeriod = 429496730;\r
	196	}\r
	197	\r
	198	//\r
	199	// Program the timer with the new count value\r
	200	//\r
ac0a286f	201	InitializeApicTimer (DivideValue, (UINT32)TimerCount, TRUE, LOCAL_APIC_TIMER_VECTOR);\r
d668c8bc AP	202	\r
	203	//\r
	204	// Enable timer interrupt\r
	205	//\r
ac0a286f	206	EnableApicTimerInterrupt ();\r
d668c8bc	207	}\r
ac0a286f	208	\r
d668c8bc AP	209	//\r
	210	// Save the new timer period\r
	211	//\r
	212	mTimerPeriod = TimerPeriod;\r
	213	\r
	214	return EFI_SUCCESS;\r
	215	}\r
	216	\r
	217	/**\r
	218	\r
	219	This function retrieves the period of timer interrupts in 100 ns units,\r
	220	returns that value in TimerPeriod, and returns EFI_SUCCESS. If TimerPeriod\r
	221	is NULL, then EFI_INVALID_PARAMETER is returned. If a TimerPeriod of 0 is\r
	222	returned, then the timer is currently disabled.\r
	223	\r
	224	\r
	225	@param This The EFI_TIMER_ARCH_PROTOCOL instance.\r
	226	@param TimerPeriod A pointer to the timer period to retrieve in 100 ns units. If\r
	227	0 is returned, then the timer is currently disabled.\r
	228	\r
	229	@retval EFI_SUCCESS The timer period was returned in TimerPeriod.\r
	230	@retval EFI_INVALID_PARAMETER TimerPeriod is NULL.\r
	231	\r
	232	**/\r
	233	EFI_STATUS\r
	234	EFIAPI\r
	235	TimerDriverGetTimerPeriod (\r
ac0a286f MK	236	IN EFI_TIMER_ARCH_PROTOCOL *This,\r
ac0a286f MK	237	OUT UINT64 *TimerPeriod\r
d668c8bc AP	238	)\r
	239	{\r
	240	if (TimerPeriod == NULL) {\r
	241	return EFI_INVALID_PARAMETER;\r
	242	}\r
	243	\r
	244	*TimerPeriod = mTimerPeriod;\r
	245	\r
	246	return EFI_SUCCESS;\r
	247	}\r
	248	\r
	249	/**\r
	250	\r
	251	This function generates a soft timer interrupt. If the platform does not support soft\r
	252	timer interrupts, then EFI_UNSUPPORTED is returned. Otherwise, EFI_SUCCESS is returned.\r
	253	If a handler has been registered through the EFI_TIMER_ARCH_PROTOCOL.RegisterHandler()\r
	254	service, then a soft timer interrupt will be generated. If the timer interrupt is\r
	255	enabled when this service is called, then the registered handler will be invoked. The\r
	256	registered handler should not be able to distinguish a hardware-generated timer\r
	257	interrupt from a software-generated timer interrupt.\r
	258	\r
	259	\r
	260	@param This The EFI_TIMER_ARCH_PROTOCOL instance.\r
	261	\r
	262	@retval EFI_SUCCESS The soft timer interrupt was generated.\r
	263	@retval EFI_UNSUPPORTED The platform does not support the generation of soft timer interrupts.\r
	264	\r
	265	**/\r
	266	EFI_STATUS\r
	267	EFIAPI\r
	268	TimerDriverGenerateSoftInterrupt (\r
	269	IN EFI_TIMER_ARCH_PROTOCOL *This\r
	270	)\r
	271	{\r
ac0a286f	272	EFI_TPL OriginalTPL;\r
d668c8bc	273	\r
ac0a286f	274	if (GetApicTimerInterruptState ()) {\r
d668c8bc AP	275	//\r
	276	// Invoke the registered handler\r
	277	//\r
	278	OriginalTPL = gBS->RaiseTPL (TPL_HIGH_LEVEL);\r
	279	\r
	280	if (mTimerNotifyFunction != NULL) {\r
	281	//\r
	282	// @bug : This does not handle missed timer interrupts\r
	283	//\r
	284	mTimerNotifyFunction (mTimerPeriod);\r
	285	}\r
	286	\r
	287	gBS->RestoreTPL (OriginalTPL);\r
	288	} else {\r
	289	return EFI_UNSUPPORTED;\r
	290	}\r
	291	\r
	292	return EFI_SUCCESS;\r
	293	}\r
	294	\r
	295	/**\r
	296	Initialize the Timer Architectural Protocol driver\r
	297	\r
	298	@param ImageHandle ImageHandle of the loaded driver\r
	299	@param SystemTable Pointer to the System Table\r
	300	\r
	301	@retval EFI_SUCCESS Timer Architectural Protocol created\r
	302	@retval EFI_OUT_OF_RESOURCES Not enough resources available to initialize driver.\r
	303	@retval EFI_DEVICE_ERROR A device error occurred attempting to initialize the driver.\r
	304	\r
	305	**/\r
	306	EFI_STATUS\r
	307	EFIAPI\r
	308	TimerDriverInitialize (\r
	309	IN EFI_HANDLE ImageHandle,\r
	310	IN EFI_SYSTEM_TABLE *SystemTable\r
	311	)\r
	312	{\r
	313	EFI_STATUS Status;\r
	314	\r
	315	//\r
	316	// Initialize the pointer to our notify function.\r
	317	//\r
	318	mTimerNotifyFunction = NULL;\r
	319	\r
	320	//\r
	321	// Make sure the Timer Architectural Protocol is not already installed in the system\r
	322	//\r
	323	ASSERT_PROTOCOL_ALREADY_INSTALLED (NULL, &gEfiTimerArchProtocolGuid);\r
	324	\r
	325	//\r
	326	// Find the CPU architectural protocol.\r
	327	//\r
ac0a286f	328	Status = gBS->LocateProtocol (&gEfiCpuArchProtocolGuid, NULL, (VOID **)&mCpu);\r
d668c8bc AP	329	ASSERT_EFI_ERROR (Status);\r
	330	\r
	331	//\r
	332	// Force the timer to be disabled\r
	333	//\r
	334	Status = TimerDriverSetTimerPeriod (&mTimer, 0);\r
	335	ASSERT_EFI_ERROR (Status);\r
	336	\r
	337	//\r
	338	// Install interrupt handler for Local APIC Timer\r
	339	//\r
ac0a286f MK	340	Status = mCpu->RegisterInterruptHandler (\r
	341	mCpu,\r
	342	LOCAL_APIC_TIMER_VECTOR,\r
	343	TimerInterruptHandler\r
	344	);\r
d668c8bc AP	345	ASSERT_EFI_ERROR (Status);\r
	346	\r
	347	//\r
	348	// Force the timer to be enabled at its default period\r
	349	//\r
	350	Status = TimerDriverSetTimerPeriod (&mTimer, DEFAULT_TIMER_TICK_DURATION);\r
	351	ASSERT_EFI_ERROR (Status);\r
	352	\r
	353	//\r
	354	// Install the Timer Architectural Protocol onto a new handle\r
	355	//\r
	356	Status = gBS->InstallMultipleProtocolInterfaces (\r
	357	&mTimerHandle,\r
ac0a286f MK	358	&gEfiTimerArchProtocolGuid,\r
ac0a286f MK	359	&mTimer,\r
d668c8bc AP	360	NULL\r
	361	);\r
	362	ASSERT_EFI_ERROR (Status);\r
	363	\r
	364	return Status;\r
	365	}\r