2 Timer Architectural Protocol as defined in the DXE CIS
4 Copyright (c) 2005 - 2018, Intel Corporation. All rights reserved.<BR>
5 SPDX-License-Identifier: BSD-2-Clause-Patent
12 // The handle onto which the Timer Architectural Protocol will be installed
14 EFI_HANDLE mTimerHandle
= NULL
;
17 // The Timer Architectural Protocol that this driver produces
19 EFI_TIMER_ARCH_PROTOCOL mTimer
= {
20 TimerDriverRegisterHandler
,
21 TimerDriverSetTimerPeriod
,
22 TimerDriverGetTimerPeriod
,
23 TimerDriverGenerateSoftInterrupt
27 // Pointer to the CPU Architectural Protocol instance
29 EFI_CPU_ARCH_PROTOCOL
*mCpu
;
32 // Pointer to the Legacy 8259 Protocol instance
34 EFI_LEGACY_8259_PROTOCOL
*mLegacy8259
;
37 // The notification function to call on every timer interrupt.
38 // A bug in the compiler prevents us from initializing this here.
40 EFI_TIMER_NOTIFY mTimerNotifyFunction
;
43 // The current period of the timer interrupt
45 volatile UINT64 mTimerPeriod
= 0;
51 Sets the counter value for Timer #0 in a legacy 8254 timer.
53 @param Count The 16-bit counter value to program into Timer #0 of the legacy 8254 timer.
60 IoWrite8 (TIMER_CONTROL_PORT
, 0x36);
61 IoWrite8 (TIMER0_COUNT_PORT
, (UINT8
)(Count
& 0xff));
62 IoWrite8 (TIMER0_COUNT_PORT
, (UINT8
)((Count
>> 8) & 0xff));
66 8254 Timer #0 Interrupt Handler.
68 @param InterruptType The type of interrupt that occurred
69 @param SystemContext A pointer to the system context when the interrupt occurred
73 TimerInterruptHandler (
74 IN EFI_EXCEPTION_TYPE InterruptType
,
75 IN EFI_SYSTEM_CONTEXT SystemContext
80 OriginalTPL
= gBS
->RaiseTPL (TPL_HIGH_LEVEL
);
82 if (mTimerNotifyFunction
!= NULL
) {
84 // @bug : This does not handle missed timer interrupts
86 mTimerNotifyFunction (mTimerPeriod
);
89 gBS
->RestoreTPL (OriginalTPL
);
92 mLegacy8259
->EndOfInterrupt (mLegacy8259
, Efi8259Irq0
);
97 This function registers the handler NotifyFunction so it is called every time
98 the timer interrupt fires. It also passes the amount of time since the last
99 handler call to the NotifyFunction. If NotifyFunction is NULL, then the
100 handler is unregistered. If the handler is registered, then EFI_SUCCESS is
101 returned. If the CPU does not support registering a timer interrupt handler,
102 then EFI_UNSUPPORTED is returned. If an attempt is made to register a handler
103 when a handler is already registered, then EFI_ALREADY_STARTED is returned.
104 If an attempt is made to unregister a handler when a handler is not registered,
105 then EFI_INVALID_PARAMETER is returned. If an error occurs attempting to
106 register the NotifyFunction with the timer interrupt, then EFI_DEVICE_ERROR
110 @param This The EFI_TIMER_ARCH_PROTOCOL instance.
111 @param NotifyFunction The function to call when a timer interrupt fires. This
112 function executes at TPL_HIGH_LEVEL. The DXE Core will
113 register a handler for the timer interrupt, so it can know
114 how much time has passed. This information is used to
115 signal timer based events. NULL will unregister the handler.
117 @retval EFI_SUCCESS The timer handler was registered.
118 @retval EFI_UNSUPPORTED The platform does not support timer interrupts.
119 @retval EFI_ALREADY_STARTED NotifyFunction is not NULL, and a handler is already
121 @retval EFI_INVALID_PARAMETER NotifyFunction is NULL, and a handler was not
122 previously registered.
123 @retval EFI_DEVICE_ERROR The timer handler could not be registered.
128 TimerDriverRegisterHandler (
129 IN EFI_TIMER_ARCH_PROTOCOL
*This
,
130 IN EFI_TIMER_NOTIFY NotifyFunction
134 // Check for invalid parameters
136 if (NotifyFunction
== NULL
&& mTimerNotifyFunction
== NULL
) {
137 return EFI_INVALID_PARAMETER
;
140 if (NotifyFunction
!= NULL
&& mTimerNotifyFunction
!= NULL
) {
141 return EFI_ALREADY_STARTED
;
144 mTimerNotifyFunction
= NotifyFunction
;
151 This function adjusts the period of timer interrupts to the value specified
152 by TimerPeriod. If the timer period is updated, then the selected timer
153 period is stored in EFI_TIMER.TimerPeriod, and EFI_SUCCESS is returned. If
154 the timer hardware is not programmable, then EFI_UNSUPPORTED is returned.
155 If an error occurs while attempting to update the timer period, then the
156 timer hardware will be put back in its state prior to this call, and
157 EFI_DEVICE_ERROR is returned. If TimerPeriod is 0, then the timer interrupt
158 is disabled. This is not the same as disabling the CPU's interrupts.
159 Instead, it must either turn off the timer hardware, or it must adjust the
160 interrupt controller so that a CPU interrupt is not generated when the timer
164 @param This The EFI_TIMER_ARCH_PROTOCOL instance.
165 @param TimerPeriod The rate to program the timer interrupt in 100 nS units. If
166 the timer hardware is not programmable, then EFI_UNSUPPORTED is
167 returned. If the timer is programmable, then the timer period
168 will be rounded up to the nearest timer period that is supported
169 by the timer hardware. If TimerPeriod is set to 0, then the
170 timer interrupts will be disabled.
172 @retval EFI_SUCCESS The timer period was changed.
173 @retval EFI_UNSUPPORTED The platform cannot change the period of the timer interrupt.
174 @retval EFI_DEVICE_ERROR The timer period could not be changed due to a device error.
179 TimerDriverSetTimerPeriod (
180 IN EFI_TIMER_ARCH_PROTOCOL
*This
,
181 IN UINT64 TimerPeriod
187 // The basic clock is 1.19318 MHz or 0.119318 ticks per 100 ns.
188 // TimerPeriod * 0.119318 = 8254 timer divisor. Using integer arithmetic
189 // TimerCount = (TimerPeriod * 119318)/1000000.
191 // Round up to next highest integer. This guarantees that the timer is
192 // equal to or slightly longer than the requested time.
193 // TimerCount = ((TimerPeriod * 119318) + 500000)/1000000
195 // Note that a TimerCount of 0 is equivalent to a count of 65,536
197 // Since TimerCount is limited to 16 bits for IA32, TimerPeriod is limited
200 if (TimerPeriod
== 0) {
202 // Disable timer interrupt for a TimerPeriod of 0
204 mLegacy8259
->DisableIrq (mLegacy8259
, Efi8259Irq0
);
208 // Convert TimerPeriod into 8254 counts
210 TimerCount
= DivU64x32 (MultU64x32 (119318, (UINT32
) TimerPeriod
) + 500000, 1000000);
213 // Check for overflow
215 if (TimerCount
>= 65536) {
217 TimerPeriod
= MAX_TIMER_TICK_DURATION
;
220 // Program the 8254 timer with the new count value
222 SetPitCount ((UINT16
) TimerCount
);
225 // Enable timer interrupt
227 mLegacy8259
->EnableIrq (mLegacy8259
, Efi8259Irq0
, FALSE
);
230 // Save the new timer period
232 mTimerPeriod
= TimerPeriod
;
239 This function retrieves the period of timer interrupts in 100 ns units,
240 returns that value in TimerPeriod, and returns EFI_SUCCESS. If TimerPeriod
241 is NULL, then EFI_INVALID_PARAMETER is returned. If a TimerPeriod of 0 is
242 returned, then the timer is currently disabled.
245 @param This The EFI_TIMER_ARCH_PROTOCOL instance.
246 @param TimerPeriod A pointer to the timer period to retrieve in 100 ns units. If
247 0 is returned, then the timer is currently disabled.
249 @retval EFI_SUCCESS The timer period was returned in TimerPeriod.
250 @retval EFI_INVALID_PARAMETER TimerPeriod is NULL.
255 TimerDriverGetTimerPeriod (
256 IN EFI_TIMER_ARCH_PROTOCOL
*This
,
257 OUT UINT64
*TimerPeriod
260 if (TimerPeriod
== NULL
) {
261 return EFI_INVALID_PARAMETER
;
264 *TimerPeriod
= mTimerPeriod
;
271 This function generates a soft timer interrupt. If the platform does not support soft
272 timer interrupts, then EFI_UNSUPPORTED is returned. Otherwise, EFI_SUCCESS is returned.
273 If a handler has been registered through the EFI_TIMER_ARCH_PROTOCOL.RegisterHandler()
274 service, then a soft timer interrupt will be generated. If the timer interrupt is
275 enabled when this service is called, then the registered handler will be invoked. The
276 registered handler should not be able to distinguish a hardware-generated timer
277 interrupt from a software-generated timer interrupt.
280 @param This The EFI_TIMER_ARCH_PROTOCOL instance.
282 @retval EFI_SUCCESS The soft timer interrupt was generated.
283 @retval EFI_UNSUPPORTED The platform does not support the generation of soft timer interrupts.
288 TimerDriverGenerateSoftInterrupt (
289 IN EFI_TIMER_ARCH_PROTOCOL
*This
297 // If the timer interrupt is enabled, then the registered handler will be invoked.
299 Status
= mLegacy8259
->GetMask (mLegacy8259
, NULL
, NULL
, &IRQMask
, NULL
);
300 ASSERT_EFI_ERROR (Status
);
301 if ((IRQMask
& 0x1) == 0) {
303 // Invoke the registered handler
305 OriginalTPL
= gBS
->RaiseTPL (TPL_HIGH_LEVEL
);
307 if (mTimerNotifyFunction
!= NULL
) {
309 // @bug : This does not handle missed timer interrupts
311 mTimerNotifyFunction (mTimerPeriod
);
314 gBS
->RestoreTPL (OriginalTPL
);
316 return EFI_UNSUPPORTED
;
323 Initialize the Timer Architectural Protocol driver
325 @param ImageHandle ImageHandle of the loaded driver
326 @param SystemTable Pointer to the System Table
328 @retval EFI_SUCCESS Timer Architectural Protocol created
329 @retval EFI_OUT_OF_RESOURCES Not enough resources available to initialize driver.
330 @retval EFI_DEVICE_ERROR A device error occurred attempting to initialize the driver.
335 TimerDriverInitialize (
336 IN EFI_HANDLE ImageHandle
,
337 IN EFI_SYSTEM_TABLE
*SystemTable
344 // Initialize the pointer to our notify function.
346 mTimerNotifyFunction
= NULL
;
349 // Make sure the Timer Architectural Protocol is not already installed in the system
351 ASSERT_PROTOCOL_ALREADY_INSTALLED (NULL
, &gEfiTimerArchProtocolGuid
);
354 // Find the CPU architectural protocol.
356 Status
= gBS
->LocateProtocol (&gEfiCpuArchProtocolGuid
, NULL
, (VOID
**) &mCpu
);
357 ASSERT_EFI_ERROR (Status
);
360 // Find the Legacy8259 protocol.
362 Status
= gBS
->LocateProtocol (&gEfiLegacy8259ProtocolGuid
, NULL
, (VOID
**) &mLegacy8259
);
363 ASSERT_EFI_ERROR (Status
);
366 // Force the timer to be disabled
368 Status
= TimerDriverSetTimerPeriod (&mTimer
, 0);
369 ASSERT_EFI_ERROR (Status
);
372 // Get the interrupt vector number corresponding to IRQ0 from the 8259 driver
375 Status
= mLegacy8259
->GetVector (mLegacy8259
, Efi8259Irq0
, (UINT8
*) &TimerVector
);
376 ASSERT_EFI_ERROR (Status
);
379 // Install interrupt handler for 8254 Timer #0 (ISA IRQ0)
381 Status
= mCpu
->RegisterInterruptHandler (mCpu
, TimerVector
, TimerInterruptHandler
);
382 ASSERT_EFI_ERROR (Status
);
385 // Force the timer to be enabled at its default period
387 Status
= TimerDriverSetTimerPeriod (&mTimer
, DEFAULT_TIMER_TICK_DURATION
);
388 ASSERT_EFI_ERROR (Status
);
391 // Install the Timer Architectural Protocol onto a new handle
393 Status
= gBS
->InstallMultipleProtocolInterfaces (
395 &gEfiTimerArchProtocolGuid
, &mTimer
,
398 ASSERT_EFI_ERROR (Status
);