[mirror_edk2.git] / OvmfPkg / XenTimerDxe / XenTimerDxe.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 "XenTimerDxe.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
  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
  SendApicEoi();\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
  UINT32  TimerFrequency;\r
  UINTN   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) / 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 (MultU64x32 (TimerPeriod, TimerFrequency),\r
                            10000000);\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, TimerCount, TRUE, LOCAL_APIC_TIMER_VECTOR);\r
\r
    //\r
    // Enable timer interrupt\r
    //\r
    EnableApicTimerInterrupt();\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 (mCpu, LOCAL_APIC_TIMER_VECTOR,\r
                                           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
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
	11	#include "XenTimerDxe.h"\r
	12	\r
	13	//\r
	14	// The handle onto which the Timer Architectural Protocol will be installed\r
	15	//\r
	16	EFI_HANDLE mTimerHandle = NULL;\r
	17	\r
	18	//\r
	19	// The Timer Architectural Protocol that this driver produces\r
	20	//\r
	21	EFI_TIMER_ARCH_PROTOCOL mTimer = {\r
	22	TimerDriverRegisterHandler,\r
	23	TimerDriverSetTimerPeriod,\r
	24	TimerDriverGetTimerPeriod,\r
	25	TimerDriverGenerateSoftInterrupt\r
	26	};\r
	27	\r
	28	//\r
	29	// Pointer to the CPU Architectural Protocol instance\r
	30	//\r
	31	EFI_CPU_ARCH_PROTOCOL *mCpu;\r
	32	\r
	33	//\r
	34	// The notification function to call on every timer interrupt.\r
	35	// A bug in the compiler prevents us from initializing this here.\r
	36	//\r
	37	EFI_TIMER_NOTIFY mTimerNotifyFunction;\r
	38	\r
	39	//\r
	40	// The current period of the timer interrupt\r
	41	//\r
	42	volatile UINT64 mTimerPeriod = 0;\r
	43	\r
	44	//\r
	45	// Worker Functions\r
	46	//\r
	47	/**\r
	48	Interrupt Handler.\r
	49	\r
	50	@param InterruptType The type of interrupt that occurred\r
	51	@param SystemContext A pointer to the system context when the interrupt occurred\r
	52	**/\r
	53	VOID\r
	54	EFIAPI\r
	55	TimerInterruptHandler (\r
	56	IN EFI_EXCEPTION_TYPE InterruptType,\r
	57	IN EFI_SYSTEM_CONTEXT SystemContext\r
	58	)\r
	59	{\r
	60	EFI_TPL OriginalTPL;\r
	61	\r
	62	OriginalTPL = gBS->RaiseTPL (TPL_HIGH_LEVEL);\r
	63	\r
	64	SendApicEoi();\r
65	\r
66	if (mTimerNotifyFunction != NULL) {\r
67	//\r
68	// @bug : This does not handle missed timer interrupts\r
69	//\r
70	mTimerNotifyFunction (mTimerPeriod);\r
71	}\r
72	\r
73	gBS->RestoreTPL (OriginalTPL);\r
74	}\r
75	\r
76	/**\r
77	\r
78	This function registers the handler NotifyFunction so it is called every time\r
79	the timer interrupt fires. It also passes the amount of time since the last\r
80	handler call to the NotifyFunction. If NotifyFunction is NULL, then the\r
81	handler is unregistered. If the handler is registered, then EFI_SUCCESS is\r
82	returned. If the CPU does not support registering a timer interrupt handler,\r
83	then EFI_UNSUPPORTED is returned. If an attempt is made to register a handler\r
84	when a handler is already registered, then EFI_ALREADY_STARTED is returned.\r
85	If an attempt is made to unregister a handler when a handler is not registered,\r
86	then EFI_INVALID_PARAMETER is returned. If an error occurs attempting to\r
87	register the NotifyFunction with the timer interrupt, then EFI_DEVICE_ERROR\r
88	is returned.\r
89	\r
90	\r
91	@param This The EFI_TIMER_ARCH_PROTOCOL instance.\r
92	@param NotifyFunction The function to call when a timer interrupt fires. This\r
93	function executes at TPL_HIGH_LEVEL. The DXE Core will\r
94	register a handler for the timer interrupt, so it can know\r
95	how much time has passed. This information is used to\r
96	signal timer based events. NULL will unregister the handler.\r
97	\r
98	@retval EFI_SUCCESS The timer handler was registered.\r
99	@retval EFI_UNSUPPORTED The platform does not support timer interrupts.\r
100	@retval EFI_ALREADY_STARTED NotifyFunction is not NULL, and a handler is already\r
101	registered.\r
102	@retval EFI_INVALID_PARAMETER NotifyFunction is NULL, and a handler was not\r
103	previously registered.\r
104	@retval EFI_DEVICE_ERROR The timer handler could not be registered.\r
105	\r
106	**/\r
107	EFI_STATUS\r
108	EFIAPI\r
109	TimerDriverRegisterHandler (\r
110	IN EFI_TIMER_ARCH_PROTOCOL *This,\r
111	IN EFI_TIMER_NOTIFY NotifyFunction\r
112	)\r
113	{\r
114	//\r
115	// Check for invalid parameters\r
116	//\r
117	if (NotifyFunction == NULL && mTimerNotifyFunction == NULL) {\r
118	return EFI_INVALID_PARAMETER;\r
119	}\r
120	\r
121	if (NotifyFunction != NULL && mTimerNotifyFunction != NULL) {\r
122	return EFI_ALREADY_STARTED;\r
123	}\r
124	\r
125	mTimerNotifyFunction = NotifyFunction;\r
126	\r
127	return EFI_SUCCESS;\r
128	}\r
129	\r
130	/**\r
131	\r
132	This function adjusts the period of timer interrupts to the value specified\r
133	by TimerPeriod. If the timer period is updated, then the selected timer\r
134	period is stored in EFI_TIMER.TimerPeriod, and EFI_SUCCESS is returned. If\r
135	the timer hardware is not programmable, then EFI_UNSUPPORTED is returned.\r
136	If an error occurs while attempting to update the timer period, then the\r
137	timer hardware will be put back in its state prior to this call, and\r
138	EFI_DEVICE_ERROR is returned. If TimerPeriod is 0, then the timer interrupt\r
139	is disabled. This is not the same as disabling the CPU's interrupts.\r
140	Instead, it must either turn off the timer hardware, or it must adjust the\r
141	interrupt controller so that a CPU interrupt is not generated when the timer\r
142	interrupt fires.\r
143	\r
144	\r
145	@param This The EFI_TIMER_ARCH_PROTOCOL instance.\r
146	@param TimerPeriod The rate to program the timer interrupt in 100 nS units. If\r
147	the timer hardware is not programmable, then EFI_UNSUPPORTED is\r
148	returned. If the timer is programmable, then the timer period\r
149	will be rounded up to the nearest timer period that is supported\r
150	by the timer hardware. If TimerPeriod is set to 0, then the\r
151	timer interrupts will be disabled.\r
152	\r
153	@retval EFI_SUCCESS The timer period was changed.\r
154	@retval EFI_UNSUPPORTED The platform cannot change the period of the timer interrupt.\r
155	@retval EFI_DEVICE_ERROR The timer period could not be changed due to a device error.\r
156	\r
157	**/\r
158	EFI_STATUS\r
159	EFIAPI\r
160	TimerDriverSetTimerPeriod (\r
161	IN EFI_TIMER_ARCH_PROTOCOL *This,\r
162	IN UINT64 TimerPeriod\r
163	)\r
164	{\r
165	UINT64 TimerCount;\r
166	UINT32 TimerFrequency;\r
167	UINTN DivideValue = 1;\r
168	\r
169	if (TimerPeriod == 0) {\r
170	//\r
171	// Disable timer interrupt for a TimerPeriod of 0\r
172	//\r
173	DisableApicTimerInterrupt();\r
174	} else {\r
175	TimerFrequency = PcdGet32(PcdFSBClock) / DivideValue;\r
176	\r
177	//\r
178	// Convert TimerPeriod into local APIC counts\r
179	//\r
180	// TimerPeriod is in 100ns\r
181	// TimerPeriod/10000000 will be in seconds.\r
182	TimerCount = DivU64x32 (MultU64x32 (TimerPeriod, TimerFrequency),\r
183	10000000);\r
184	\r
185	// Check for overflow\r
186	if (TimerCount > MAX_UINT32) {\r
187	TimerCount = MAX_UINT32;\r
188	/* TimerPeriod = (MAX_UINT32 / TimerFrequency) * 10000000; */\r
189	TimerPeriod = 429496730;\r
190	}\r
191	\r
192	//\r
193	// Program the timer with the new count value\r
194	//\r
195	InitializeApicTimer(DivideValue, TimerCount, TRUE, LOCAL_APIC_TIMER_VECTOR);\r
196	\r
197	//\r
198	// Enable timer interrupt\r
199	//\r
200	EnableApicTimerInterrupt();\r
201	}\r
202	//\r
203	// Save the new timer period\r
204	//\r
205	mTimerPeriod = TimerPeriod;\r
206	\r
207	return EFI_SUCCESS;\r
208	}\r
209	\r
210	/**\r
211	\r
212	This function retrieves the period of timer interrupts in 100 ns units,\r
213	returns that value in TimerPeriod, and returns EFI_SUCCESS. If TimerPeriod\r
214	is NULL, then EFI_INVALID_PARAMETER is returned. If a TimerPeriod of 0 is\r
215	returned, then the timer is currently disabled.\r
216	\r
217	\r
218	@param This The EFI_TIMER_ARCH_PROTOCOL instance.\r
219	@param TimerPeriod A pointer to the timer period to retrieve in 100 ns units. If\r
220	0 is returned, then the timer is currently disabled.\r
221	\r
222	@retval EFI_SUCCESS The timer period was returned in TimerPeriod.\r
223	@retval EFI_INVALID_PARAMETER TimerPeriod is NULL.\r
224	\r
225	**/\r
226	EFI_STATUS\r
227	EFIAPI\r
228	TimerDriverGetTimerPeriod (\r
229	IN EFI_TIMER_ARCH_PROTOCOL *This,\r
230	OUT UINT64 *TimerPeriod\r
231	)\r
232	{\r
233	if (TimerPeriod == NULL) {\r
234	return EFI_INVALID_PARAMETER;\r
235	}\r
236	\r
237	*TimerPeriod = mTimerPeriod;\r
238	\r
239	return EFI_SUCCESS;\r
240	}\r
241	\r
242	/**\r
243	\r
244	This function generates a soft timer interrupt. If the platform does not support soft\r
245	timer interrupts, then EFI_UNSUPPORTED is returned. Otherwise, EFI_SUCCESS is returned.\r
246	If a handler has been registered through the EFI_TIMER_ARCH_PROTOCOL.RegisterHandler()\r
247	service, then a soft timer interrupt will be generated. If the timer interrupt is\r
248	enabled when this service is called, then the registered handler will be invoked. The\r
249	registered handler should not be able to distinguish a hardware-generated timer\r
250	interrupt from a software-generated timer interrupt.\r
251	\r
252	\r
253	@param This The EFI_TIMER_ARCH_PROTOCOL instance.\r
254	\r
255	@retval EFI_SUCCESS The soft timer interrupt was generated.\r
256	@retval EFI_UNSUPPORTED The platform does not support the generation of soft timer interrupts.\r
257	\r
258	**/\r
259	EFI_STATUS\r
260	EFIAPI\r
261	TimerDriverGenerateSoftInterrupt (\r
262	IN EFI_TIMER_ARCH_PROTOCOL *This\r
263	)\r
264	{\r
265	EFI_TPL OriginalTPL;\r
266	\r
267	if (GetApicTimerInterruptState()) {\r
268	//\r
269	// Invoke the registered handler\r
270	//\r
271	OriginalTPL = gBS->RaiseTPL (TPL_HIGH_LEVEL);\r
272	\r
273	if (mTimerNotifyFunction != NULL) {\r
274	//\r
275	// @bug : This does not handle missed timer interrupts\r
276	//\r
277	mTimerNotifyFunction (mTimerPeriod);\r
278	}\r
279	\r
280	gBS->RestoreTPL (OriginalTPL);\r
281	} else {\r
282	return EFI_UNSUPPORTED;\r
283	}\r
284	\r
285	return EFI_SUCCESS;\r
286	}\r
287	\r
288	/**\r
289	Initialize the Timer Architectural Protocol driver\r
290	\r
291	@param ImageHandle ImageHandle of the loaded driver\r
292	@param SystemTable Pointer to the System Table\r
293	\r
294	@retval EFI_SUCCESS Timer Architectural Protocol created\r
295	@retval EFI_OUT_OF_RESOURCES Not enough resources available to initialize driver.\r
296	@retval EFI_DEVICE_ERROR A device error occurred attempting to initialize the driver.\r
297	\r
298	**/\r
299	EFI_STATUS\r
300	EFIAPI\r
301	TimerDriverInitialize (\r
302	IN EFI_HANDLE ImageHandle,\r
303	IN EFI_SYSTEM_TABLE *SystemTable\r
304	)\r
305	{\r
306	EFI_STATUS Status;\r
307	\r
308	//\r
309	// Initialize the pointer to our notify function.\r
310	//\r
311	mTimerNotifyFunction = NULL;\r
312	\r
313	//\r
314	// Make sure the Timer Architectural Protocol is not already installed in the system\r
315	//\r
316	ASSERT_PROTOCOL_ALREADY_INSTALLED (NULL, &gEfiTimerArchProtocolGuid);\r
317	\r
318	//\r
319	// Find the CPU architectural protocol.\r
320	//\r
321	Status = gBS->LocateProtocol (&gEfiCpuArchProtocolGuid, NULL, (VOID **) &mCpu);\r
322	ASSERT_EFI_ERROR (Status);\r
323	\r
324	//\r
325	// Force the timer to be disabled\r
326	//\r
327	Status = TimerDriverSetTimerPeriod (&mTimer, 0);\r
328	ASSERT_EFI_ERROR (Status);\r
329	\r
330	//\r
331	// Install interrupt handler for Local APIC Timer\r
332	//\r
333	Status = mCpu->RegisterInterruptHandler (mCpu, LOCAL_APIC_TIMER_VECTOR,\r
334	TimerInterruptHandler);\r
335	ASSERT_EFI_ERROR (Status);\r
336	\r
337	//\r
338	// Force the timer to be enabled at its default period\r
339	//\r
340	Status = TimerDriverSetTimerPeriod (&mTimer, DEFAULT_TIMER_TICK_DURATION);\r
341	ASSERT_EFI_ERROR (Status);\r
342	\r
343	//\r
344	// Install the Timer Architectural Protocol onto a new handle\r
345	//\r
346	Status = gBS->InstallMultipleProtocolInterfaces (\r
347	&mTimerHandle,\r
348	&gEfiTimerArchProtocolGuid, &mTimer,\r
349	NULL\r
350	);\r
351	ASSERT_EFI_ERROR (Status);\r
352	\r
353	return Status;\r
354	}\r
355	\r