[mirror_edk2.git] / PcAtChipsetPkg / 8254TimerDxe / Timer.c

/** @file\r
  Timer Architectural Protocol as defined in the DXE CIS\r
\r
Copyright (c) 2005 - 2016, Intel Corporation. All rights reserved.<BR>\r
This program and the accompanying materials                          \r
are licensed and made available under the terms and conditions of the BSD License         \r
which accompanies this distribution.  The full text of the license may be found at        \r
http://opensource.org/licenses/bsd-license.php                                            \r
                                                                                          \r
THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,                     \r
WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.             \r
\r
**/\r
\r
#include "Timer.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
// Pointer to the Legacy 8259 Protocol instance\r
//\r
EFI_LEGACY_8259_PROTOCOL  *mLegacy8259;\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
  Sets the counter value for Timer #0 in a legacy 8254 timer.\r
\r
  @param Count    The 16-bit counter value to program into Timer #0 of the legacy 8254 timer.\r
**/\r
VOID\r
SetPitCount (\r
  IN UINT16  Count\r
  )\r
{\r
  IoWrite8 (TIMER_CONTROL_PORT, 0x36);\r
  IoWrite8 (TIMER0_COUNT_PORT, (UINT8)(Count & 0xff));\r
  IoWrite8 (TIMER0_COUNT_PORT, (UINT8)((Count >> 8) & 0xff));\r
}\r
\r
/**\r
  8254 Timer #0 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
  EFI_TPL OriginalTPL;\r
\r
  OriginalTPL = gBS->RaiseTPL (TPL_HIGH_LEVEL);\r
\r
  mLegacy8259->EndOfInterrupt (mLegacy8259, Efi8259Irq0);\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
}\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
\r
  //\r
  //  The basic clock is 1.19318 MHz or 0.119318 ticks per 100 ns.\r
  //  TimerPeriod * 0.119318 = 8254 timer divisor. Using integer arithmetic\r
  //  TimerCount = (TimerPeriod * 119318)/1000000.\r
  //\r
  //  Round up to next highest integer. This guarantees that the timer is\r
  //  equal to or slightly longer than the requested time.\r
  //  TimerCount = ((TimerPeriod * 119318) + 500000)/1000000\r
  //\r
  // Note that a TimerCount of 0 is equivalent to a count of 65,536\r
  //\r
  // Since TimerCount is limited to 16 bits for IA32, TimerPeriod is limited\r
  // to 20 bits.\r
  //\r
  if (TimerPeriod == 0) {\r
    //\r
    // Disable timer interrupt for a TimerPeriod of 0\r
    //\r
    mLegacy8259->DisableIrq (mLegacy8259, Efi8259Irq0);\r
  } else {\r
\r
    //\r
    // Convert TimerPeriod into 8254 counts\r
    //\r
    TimerCount = DivU64x32 (MultU64x32 (119318, (UINT32) TimerPeriod) + 500000, 1000000);\r
\r
    //\r
    // Check for overflow\r
    //\r
    if (TimerCount >= 65536) {\r
      TimerCount = 0;\r
      TimerPeriod = MAX_TIMER_TICK_DURATION;\r
    }\r
    //\r
    // Program the 8254 timer with the new count value\r
    //\r
    SetPitCount ((UINT16) TimerCount);\r
\r
    //\r
    // Enable timer interrupt\r
    //\r
    mLegacy8259->EnableIrq (mLegacy8259, Efi8259Irq0, FALSE);\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_STATUS  Status;\r
  UINT16      IRQMask;\r
  EFI_TPL     OriginalTPL;\r
  \r
  //\r
  // If the timer interrupt is enabled, then the registered handler will be invoked.\r
  //\r
  Status = mLegacy8259->GetMask (mLegacy8259, NULL, NULL, &IRQMask, NULL);\r
  ASSERT_EFI_ERROR (Status);\r
  if ((IRQMask & 0x1) == 0) {\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
  UINT32      TimerVector;\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
  // Find the Legacy8259 protocol.\r
  //\r
  Status = gBS->LocateProtocol (&gEfiLegacy8259ProtocolGuid, NULL, (VOID **) &mLegacy8259);\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
  // Get the interrupt vector number corresponding to IRQ0 from the 8259 driver\r
  //\r
  TimerVector = 0;\r
  Status      = mLegacy8259->GetVector (mLegacy8259, Efi8259Irq0, (UINT8 *) &TimerVector);\r
  ASSERT_EFI_ERROR (Status);\r
\r
  //\r
  // Install interrupt handler for 8254 Timer #0 (ISA IRQ0)\r
  //\r
  Status = mCpu->RegisterInterruptHandler (mCpu, TimerVector, TimerInterruptHandler);\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, &mTimer,\r
                  NULL\r
                  );\r
  ASSERT_EFI_ERROR (Status);\r
\r
  return Status;\r
}\r
\r
Commit	Line	Data
	1	/** @file\r
	2	Timer Architectural Protocol as defined in the DXE CIS\r
	3	\r
	4	Copyright (c) 2005 - 2016, Intel Corporation. All rights reserved.<BR>\r
	5	This program and the accompanying materials \r
	6	are licensed and made available under the terms and conditions of the BSD License \r
	7	which accompanies this distribution. The full text of the license may be found at \r
	8	http://opensource.org/licenses/bsd-license.php \r
	9	\r
	10	THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, \r
	11	WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED. \r
	12	\r
	13	**/\r
	14	\r
	15	#include "Timer.h"\r
	16	\r
	17	//\r
	18	// The handle onto which the Timer Architectural Protocol will be installed\r
	19	//\r
	20	EFI_HANDLE mTimerHandle = NULL;\r
	21	\r
	22	//\r
	23	// The Timer Architectural Protocol that this driver produces\r
	24	//\r
	25	EFI_TIMER_ARCH_PROTOCOL mTimer = {\r
	26	TimerDriverRegisterHandler,\r
	27	TimerDriverSetTimerPeriod,\r
	28	TimerDriverGetTimerPeriod,\r
	29	TimerDriverGenerateSoftInterrupt\r
	30	};\r
	31	\r
	32	//\r
	33	// Pointer to the CPU Architectural Protocol instance\r
	34	//\r
	35	EFI_CPU_ARCH_PROTOCOL *mCpu;\r
	36	\r
	37	//\r
	38	// Pointer to the Legacy 8259 Protocol instance\r
	39	//\r
	40	EFI_LEGACY_8259_PROTOCOL *mLegacy8259;\r
	41	\r
	42	//\r
	43	// The notification function to call on every timer interrupt.\r
	44	// A bug in the compiler prevents us from initializing this here.\r
	45	//\r
	46	EFI_TIMER_NOTIFY mTimerNotifyFunction;\r
	47	\r
	48	//\r
	49	// The current period of the timer interrupt\r
	50	//\r
	51	volatile UINT64 mTimerPeriod = 0;\r
	52	\r
	53	//\r
	54	// Worker Functions\r
	55	//\r
	56	/**\r
	57	Sets the counter value for Timer #0 in a legacy 8254 timer.\r
	58	\r
	59	@param Count The 16-bit counter value to program into Timer #0 of the legacy 8254 timer.\r
	60	**/\r
	61	VOID\r
	62	SetPitCount (\r
	63	IN UINT16 Count\r
	64	)\r
	65	{\r
	66	IoWrite8 (TIMER_CONTROL_PORT, 0x36);\r
	67	IoWrite8 (TIMER0_COUNT_PORT, (UINT8)(Count & 0xff));\r
	68	IoWrite8 (TIMER0_COUNT_PORT, (UINT8)((Count >> 8) & 0xff));\r
	69	}\r
	70	\r
	71	/**\r
	72	8254 Timer #0 Interrupt Handler.\r
	73	\r
	74	@param InterruptType The type of interrupt that occurred\r
	75	@param SystemContext A pointer to the system context when the interrupt occurred\r
	76	**/\r
	77	VOID\r
	78	EFIAPI\r
	79	TimerInterruptHandler (\r
	80	IN EFI_EXCEPTION_TYPE InterruptType,\r
	81	IN EFI_SYSTEM_CONTEXT SystemContext\r
	82	)\r
	83	{\r
	84	EFI_TPL OriginalTPL;\r
	85	\r
	86	OriginalTPL = gBS->RaiseTPL (TPL_HIGH_LEVEL);\r
	87	\r
	88	mLegacy8259->EndOfInterrupt (mLegacy8259, Efi8259Irq0);\r
	89	\r
	90	if (mTimerNotifyFunction != NULL) {\r
	91	//\r
	92	// @bug : This does not handle missed timer interrupts\r
	93	//\r
	94	mTimerNotifyFunction (mTimerPeriod);\r
	95	}\r
	96	\r
	97	gBS->RestoreTPL (OriginalTPL);\r
	98	}\r
	99	\r
	100	/**\r
	101	\r
	102	This function registers the handler NotifyFunction so it is called every time\r
	103	the timer interrupt fires. It also passes the amount of time since the last\r
	104	handler call to the NotifyFunction. If NotifyFunction is NULL, then the\r
	105	handler is unregistered. If the handler is registered, then EFI_SUCCESS is\r
	106	returned. If the CPU does not support registering a timer interrupt handler,\r
	107	then EFI_UNSUPPORTED is returned. If an attempt is made to register a handler\r
	108	when a handler is already registered, then EFI_ALREADY_STARTED is returned.\r
	109	If an attempt is made to unregister a handler when a handler is not registered,\r
	110	then EFI_INVALID_PARAMETER is returned. If an error occurs attempting to\r
	111	register the NotifyFunction with the timer interrupt, then EFI_DEVICE_ERROR\r
	112	is returned.\r
	113	\r
	114	\r
	115	@param This The EFI_TIMER_ARCH_PROTOCOL instance.\r
	116	@param NotifyFunction The function to call when a timer interrupt fires. This\r
	117	function executes at TPL_HIGH_LEVEL. The DXE Core will\r
	118	register a handler for the timer interrupt, so it can know\r
	119	how much time has passed. This information is used to\r
	120	signal timer based events. NULL will unregister the handler.\r
	121	\r
	122	@retval EFI_SUCCESS The timer handler was registered.\r
	123	@retval EFI_UNSUPPORTED The platform does not support timer interrupts.\r
	124	@retval EFI_ALREADY_STARTED NotifyFunction is not NULL, and a handler is already\r
	125	registered.\r
	126	@retval EFI_INVALID_PARAMETER NotifyFunction is NULL, and a handler was not\r
	127	previously registered.\r
	128	@retval EFI_DEVICE_ERROR The timer handler could not be registered.\r
	129	\r
	130	**/\r
	131	EFI_STATUS\r
	132	EFIAPI\r
	133	TimerDriverRegisterHandler (\r
	134	IN EFI_TIMER_ARCH_PROTOCOL *This,\r
	135	IN EFI_TIMER_NOTIFY NotifyFunction\r
	136	)\r
	137	{\r
	138	//\r
	139	// Check for invalid parameters\r
	140	//\r
	141	if (NotifyFunction == NULL && mTimerNotifyFunction == NULL) {\r
	142	return EFI_INVALID_PARAMETER;\r
	143	}\r
	144	\r
	145	if (NotifyFunction != NULL && mTimerNotifyFunction != NULL) {\r
	146	return EFI_ALREADY_STARTED;\r
	147	}\r
	148	\r
	149	mTimerNotifyFunction = NotifyFunction;\r
	150	\r
	151	return EFI_SUCCESS;\r
	152	}\r
	153	\r
	154	/**\r
	155	\r
	156	This function adjusts the period of timer interrupts to the value specified\r
	157	by TimerPeriod. If the timer period is updated, then the selected timer\r
	158	period is stored in EFI_TIMER.TimerPeriod, and EFI_SUCCESS is returned. If\r
	159	the timer hardware is not programmable, then EFI_UNSUPPORTED is returned.\r
	160	If an error occurs while attempting to update the timer period, then the\r
	161	timer hardware will be put back in its state prior to this call, and\r
	162	EFI_DEVICE_ERROR is returned. If TimerPeriod is 0, then the timer interrupt\r
	163	is disabled. This is not the same as disabling the CPU's interrupts.\r
	164	Instead, it must either turn off the timer hardware, or it must adjust the\r
	165	interrupt controller so that a CPU interrupt is not generated when the timer\r
	166	interrupt fires.\r
	167	\r
	168	\r
	169	@param This The EFI_TIMER_ARCH_PROTOCOL instance.\r
	170	@param TimerPeriod The rate to program the timer interrupt in 100 nS units. If\r
	171	the timer hardware is not programmable, then EFI_UNSUPPORTED is\r
	172	returned. If the timer is programmable, then the timer period\r
	173	will be rounded up to the nearest timer period that is supported\r
	174	by the timer hardware. If TimerPeriod is set to 0, then the\r
	175	timer interrupts will be disabled.\r
	176	\r
	177	@retval EFI_SUCCESS The timer period was changed.\r
	178	@retval EFI_UNSUPPORTED The platform cannot change the period of the timer interrupt.\r
	179	@retval EFI_DEVICE_ERROR The timer period could not be changed due to a device error.\r
	180	\r
	181	**/\r
	182	EFI_STATUS\r
	183	EFIAPI\r
	184	TimerDriverSetTimerPeriod (\r
	185	IN EFI_TIMER_ARCH_PROTOCOL *This,\r
	186	IN UINT64 TimerPeriod\r
	187	)\r
	188	{\r
	189	UINT64 TimerCount;\r
	190	\r
	191	//\r
	192	// The basic clock is 1.19318 MHz or 0.119318 ticks per 100 ns.\r
	193	// TimerPeriod * 0.119318 = 8254 timer divisor. Using integer arithmetic\r
	194	// TimerCount = (TimerPeriod * 119318)/1000000.\r
	195	//\r
	196	// Round up to next highest integer. This guarantees that the timer is\r
	197	// equal to or slightly longer than the requested time.\r
	198	// TimerCount = ((TimerPeriod * 119318) + 500000)/1000000\r
	199	//\r
	200	// Note that a TimerCount of 0 is equivalent to a count of 65,536\r
	201	//\r
	202	// Since TimerCount is limited to 16 bits for IA32, TimerPeriod is limited\r
	203	// to 20 bits.\r
	204	//\r
	205	if (TimerPeriod == 0) {\r
	206	//\r
	207	// Disable timer interrupt for a TimerPeriod of 0\r
	208	//\r
	209	mLegacy8259->DisableIrq (mLegacy8259, Efi8259Irq0);\r
	210	} else {\r
	211	\r
	212	//\r
	213	// Convert TimerPeriod into 8254 counts\r
	214	//\r
	215	TimerCount = DivU64x32 (MultU64x32 (119318, (UINT32) TimerPeriod) + 500000, 1000000);\r
	216	\r
	217	//\r
	218	// Check for overflow\r
	219	//\r
	220	if (TimerCount >= 65536) {\r
	221	TimerCount = 0;\r
	222	TimerPeriod = MAX_TIMER_TICK_DURATION;\r
	223	}\r
	224	//\r
	225	// Program the 8254 timer with the new count value\r
	226	//\r
	227	SetPitCount ((UINT16) TimerCount);\r
	228	\r
	229	//\r
	230	// Enable timer interrupt\r
	231	//\r
	232	mLegacy8259->EnableIrq (mLegacy8259, Efi8259Irq0, FALSE);\r
	233	}\r
	234	//\r
	235	// Save the new timer period\r
	236	//\r
	237	mTimerPeriod = TimerPeriod;\r
	238	\r
	239	return EFI_SUCCESS;\r
	240	}\r
	241	\r
	242	/**\r
	243	\r
	244	This function retrieves the period of timer interrupts in 100 ns units,\r
	245	returns that value in TimerPeriod, and returns EFI_SUCCESS. If TimerPeriod\r
	246	is NULL, then EFI_INVALID_PARAMETER is returned. If a TimerPeriod of 0 is\r
	247	returned, then the timer is currently disabled.\r
	248	\r
	249	\r
	250	@param This The EFI_TIMER_ARCH_PROTOCOL instance.\r
	251	@param TimerPeriod A pointer to the timer period to retrieve in 100 ns units. If\r
	252	0 is returned, then the timer is currently disabled.\r
	253	\r
	254	@retval EFI_SUCCESS The timer period was returned in TimerPeriod.\r
	255	@retval EFI_INVALID_PARAMETER TimerPeriod is NULL.\r
	256	\r
	257	**/\r
	258	EFI_STATUS\r
	259	EFIAPI\r
	260	TimerDriverGetTimerPeriod (\r
	261	IN EFI_TIMER_ARCH_PROTOCOL *This,\r
	262	OUT UINT64 *TimerPeriod\r
	263	)\r
	264	{\r
	265	if (TimerPeriod == NULL) {\r
	266	return EFI_INVALID_PARAMETER;\r
	267	}\r
	268	\r
	269	*TimerPeriod = mTimerPeriod;\r
	270	\r
	271	return EFI_SUCCESS;\r
	272	}\r
	273	\r
	274	/**\r
	275	\r
	276	This function generates a soft timer interrupt. If the platform does not support soft\r
	277	timer interrupts, then EFI_UNSUPPORTED is returned. Otherwise, EFI_SUCCESS is returned.\r
	278	If a handler has been registered through the EFI_TIMER_ARCH_PROTOCOL.RegisterHandler()\r
	279	service, then a soft timer interrupt will be generated. If the timer interrupt is\r
	280	enabled when this service is called, then the registered handler will be invoked. The\r
	281	registered handler should not be able to distinguish a hardware-generated timer\r
	282	interrupt from a software-generated timer interrupt.\r
	283	\r
	284	\r
	285	@param This The EFI_TIMER_ARCH_PROTOCOL instance.\r
	286	\r
	287	@retval EFI_SUCCESS The soft timer interrupt was generated.\r
	288	@retval EFI_UNSUPPORTED The platform does not support the generation of soft timer interrupts.\r
	289	\r
	290	**/\r
	291	EFI_STATUS\r
	292	EFIAPI\r
	293	TimerDriverGenerateSoftInterrupt (\r
	294	IN EFI_TIMER_ARCH_PROTOCOL *This\r
	295	)\r
	296	{\r
	297	EFI_STATUS Status;\r
	298	UINT16 IRQMask;\r
	299	EFI_TPL OriginalTPL;\r
	300	\r
	301	//\r
	302	// If the timer interrupt is enabled, then the registered handler will be invoked.\r
	303	//\r
	304	Status = mLegacy8259->GetMask (mLegacy8259, NULL, NULL, &IRQMask, NULL);\r
	305	ASSERT_EFI_ERROR (Status);\r
	306	if ((IRQMask & 0x1) == 0) {\r
	307	//\r
	308	// Invoke the registered handler\r
	309	//\r
	310	OriginalTPL = gBS->RaiseTPL (TPL_HIGH_LEVEL);\r
	311	\r
	312	if (mTimerNotifyFunction != NULL) {\r
	313	//\r
	314	// @bug : This does not handle missed timer interrupts\r
	315	//\r
	316	mTimerNotifyFunction (mTimerPeriod);\r
	317	}\r
	318	\r
	319	gBS->RestoreTPL (OriginalTPL);\r
	320	} else {\r
	321	return EFI_UNSUPPORTED;\r
	322	}\r
	323	\r
	324	return EFI_SUCCESS;\r
	325	}\r
	326	\r
	327	/**\r
	328	Initialize the Timer Architectural Protocol driver\r
	329	\r
	330	@param ImageHandle ImageHandle of the loaded driver\r
	331	@param SystemTable Pointer to the System Table\r
	332	\r
	333	@retval EFI_SUCCESS Timer Architectural Protocol created\r
	334	@retval EFI_OUT_OF_RESOURCES Not enough resources available to initialize driver.\r
	335	@retval EFI_DEVICE_ERROR A device error occurred attempting to initialize the driver.\r
	336	\r
	337	**/\r
	338	EFI_STATUS\r
	339	EFIAPI\r
	340	TimerDriverInitialize (\r
	341	IN EFI_HANDLE ImageHandle,\r
	342	IN EFI_SYSTEM_TABLE *SystemTable\r
	343	)\r
	344	{\r
	345	EFI_STATUS Status;\r
	346	UINT32 TimerVector;\r
	347	\r
	348	//\r
	349	// Initialize the pointer to our notify function.\r
	350	//\r
	351	mTimerNotifyFunction = NULL;\r
	352	\r
	353	//\r
	354	// Make sure the Timer Architectural Protocol is not already installed in the system\r
	355	//\r
	356	ASSERT_PROTOCOL_ALREADY_INSTALLED (NULL, &gEfiTimerArchProtocolGuid);\r
	357	\r
	358	//\r
	359	// Find the CPU architectural protocol.\r
	360	//\r
	361	Status = gBS->LocateProtocol (&gEfiCpuArchProtocolGuid, NULL, (VOID **) &mCpu);\r
	362	ASSERT_EFI_ERROR (Status);\r
	363	\r
	364	//\r
	365	// Find the Legacy8259 protocol.\r
	366	//\r
	367	Status = gBS->LocateProtocol (&gEfiLegacy8259ProtocolGuid, NULL, (VOID **) &mLegacy8259);\r
	368	ASSERT_EFI_ERROR (Status);\r
	369	\r
	370	//\r
	371	// Force the timer to be disabled\r
	372	//\r
	373	Status = TimerDriverSetTimerPeriod (&mTimer, 0);\r
	374	ASSERT_EFI_ERROR (Status);\r
	375	\r
	376	//\r
	377	// Get the interrupt vector number corresponding to IRQ0 from the 8259 driver\r
	378	//\r
	379	TimerVector = 0;\r
	380	Status = mLegacy8259->GetVector (mLegacy8259, Efi8259Irq0, (UINT8 *) &TimerVector);\r
	381	ASSERT_EFI_ERROR (Status);\r
	382	\r
	383	//\r
	384	// Install interrupt handler for 8254 Timer #0 (ISA IRQ0)\r
	385	//\r
	386	Status = mCpu->RegisterInterruptHandler (mCpu, TimerVector, TimerInterruptHandler);\r
	387	ASSERT_EFI_ERROR (Status);\r
	388	\r
	389	//\r
	390	// Force the timer to be enabled at its default period\r
	391	//\r
	392	Status = TimerDriverSetTimerPeriod (&mTimer, DEFAULT_TIMER_TICK_DURATION);\r
	393	ASSERT_EFI_ERROR (Status);\r
	394	\r
	395	//\r
	396	// Install the Timer Architectural Protocol onto a new handle\r
	397	//\r
	398	Status = gBS->InstallMultipleProtocolInterfaces (\r
	399	&mTimerHandle,\r
	400	&gEfiTimerArchProtocolGuid, &mTimer,\r
	401	NULL\r
	402	);\r
	403	ASSERT_EFI_ERROR (Status);\r
	404	\r
	405	return Status;\r
	406	}\r
	407	\r