4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync Timer Architectural Protocol as defined in the DXE CIS
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsyncCopyright (c) 2005 - 2010, Intel Corporation. All rights reserved.<BR>
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsyncThis program and the accompanying materials
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsyncare licensed and made available under the terms and conditions of the BSD License
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsyncwhich accompanies this distribution. The full text of the license may be found at
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsyncTHE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsyncWITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync// The handle onto which the Timer Architectural Protocol will be installed
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync// The Timer Architectural Protocol that this driver produces
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync// Pointer to the CPU Architectural Protocol instance
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync// Pointer to the Legacy 8259 Protocol instance
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync// The notification function to call on every timer interrupt.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync// A bug in the compiler prevents us from initializing this here.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync// The current period of the timer interrupt
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync// Worker Functions
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync Sets the counter value for Timer #0 in a legacy 8254 timer.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @param Count The 16-bit counter value to program into Timer #0 of the legacy 8254 timer.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync IoWrite8 (TIMER0_COUNT_PORT, (UINT8)(Count & 0xff));
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync IoWrite8 (TIMER0_COUNT_PORT, (UINT8)((Count >> 8) & 0xff));
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync 8254 Timer #0 Interrupt Handler.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @param InterruptType The type of interrupt that occured
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @param SystemContext A pointer to the system context when the interrupt occured
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync mLegacy8259->EndOfInterrupt (mLegacy8259, Efi8259Irq0);
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // @bug : This does not handle missed timer interrupts
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync This function registers the handler NotifyFunction so it is called every time
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync the timer interrupt fires. It also passes the amount of time since the last
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync handler call to the NotifyFunction. If NotifyFunction is NULL, then the
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync handler is unregistered. If the handler is registered, then EFI_SUCCESS is
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync returned. If the CPU does not support registering a timer interrupt handler,
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync then EFI_UNSUPPORTED is returned. If an attempt is made to register a handler
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync when a handler is already registered, then EFI_ALREADY_STARTED is returned.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync If an attempt is made to unregister a handler when a handler is not registered,
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync then EFI_INVALID_PARAMETER is returned. If an error occurs attempting to
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync register the NotifyFunction with the timer interrupt, then EFI_DEVICE_ERROR
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync is returned.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @param This The EFI_TIMER_ARCH_PROTOCOL instance.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @param NotifyFunction The function to call when a timer interrupt fires. This
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync function executes at TPL_HIGH_LEVEL. The DXE Core will
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync register a handler for the timer interrupt, so it can know
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync how much time has passed. This information is used to
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync signal timer based events. NULL will unregister the handler.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @retval EFI_SUCCESS The timer handler was registered.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @retval EFI_UNSUPPORTED The platform does not support timer interrupts.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @retval EFI_ALREADY_STARTED NotifyFunction is not NULL, and a handler is already
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync registered.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @retval EFI_INVALID_PARAMETER NotifyFunction is NULL, and a handler was not
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync previously registered.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @retval EFI_DEVICE_ERROR The timer handler could not be registered.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Check for invalid parameters
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync if (NotifyFunction == NULL && mTimerNotifyFunction == NULL) {
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync if (NotifyFunction != NULL && mTimerNotifyFunction != NULL) {
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync This function adjusts the period of timer interrupts to the value specified
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync by TimerPeriod. If the timer period is updated, then the selected timer
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync period is stored in EFI_TIMER.TimerPeriod, and EFI_SUCCESS is returned. If
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync the timer hardware is not programmable, then EFI_UNSUPPORTED is returned.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync If an error occurs while attempting to update the timer period, then the
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync timer hardware will be put back in its state prior to this call, and
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync EFI_DEVICE_ERROR is returned. If TimerPeriod is 0, then the timer interrupt
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync is disabled. This is not the same as disabling the CPU's interrupts.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync Instead, it must either turn off the timer hardware, or it must adjust the
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync interrupt controller so that a CPU interrupt is not generated when the timer
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync interrupt fires.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @param This The EFI_TIMER_ARCH_PROTOCOL instance.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @param TimerPeriod The rate to program the timer interrupt in 100 nS units. If
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync the timer hardware is not programmable, then EFI_UNSUPPORTED is
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync returned. If the timer is programmable, then the timer period
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync will be rounded up to the nearest timer period that is supported
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync by the timer hardware. If TimerPeriod is set to 0, then the
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync timer interrupts will be disabled.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @retval EFI_SUCCESS The timer period was changed.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @retval EFI_UNSUPPORTED The platform cannot change the period of the timer interrupt.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @retval EFI_DEVICE_ERROR The timer period could not be changed due to a device error.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // The basic clock is 1.19318 MHz or 0.119318 ticks per 100 ns.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // TimerPeriod * 0.119318 = 8254 timer divisor. Using integer arithmetic
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // TimerCount = (TimerPeriod * 119318)/1000000.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Round up to next highest integer. This guarantees that the timer is
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // equal to or slightly longer than the requested time.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // TimerCount = ((TimerPeriod * 119318) + 500000)/1000000
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Note that a TimerCount of 0 is equivalent to a count of 65,536
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Since TimerCount is limited to 16 bits for IA32, TimerPeriod is limited
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // to 20 bits.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Disable timer interrupt for a TimerPeriod of 0
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync mLegacy8259->DisableIrq (mLegacy8259, Efi8259Irq0);
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Convert TimerPeriod into 8254 counts
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync TimerCount = DivU64x32 (MultU64x32 (119318, (UINT32) TimerPeriod) + 500000, 1000000);
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Check for overflow
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Program the 8254 timer with the new count value
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Enable timer interrupt
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync mLegacy8259->EnableIrq (mLegacy8259, Efi8259Irq0, FALSE);
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Save the new timer period
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync This function retrieves the period of timer interrupts in 100 ns units,
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync returns that value in TimerPeriod, and returns EFI_SUCCESS. If TimerPeriod
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync is NULL, then EFI_INVALID_PARAMETER is returned. If a TimerPeriod of 0 is
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync returned, then the timer is currently disabled.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @param This The EFI_TIMER_ARCH_PROTOCOL instance.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @param TimerPeriod A pointer to the timer period to retrieve in 100 ns units. If
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync 0 is returned, then the timer is currently disabled.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @retval EFI_SUCCESS The timer period was returned in TimerPeriod.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @retval EFI_INVALID_PARAMETER TimerPeriod is NULL.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync This function generates a soft timer interrupt. If the platform does not support soft
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync timer interrupts, then EFI_UNSUPPORTED is returned. Otherwise, EFI_SUCCESS is returned.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync If a handler has been registered through the EFI_TIMER_ARCH_PROTOCOL.RegisterHandler()
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync service, then a soft timer interrupt will be generated. If the timer interrupt is
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync enabled when this service is called, then the registered handler will be invoked. The
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync registered handler should not be able to distinguish a hardware-generated timer
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync interrupt from a software-generated timer interrupt.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @param This The EFI_TIMER_ARCH_PROTOCOL instance.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @retval EFI_SUCCESS The soft timer interrupt was generated.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @retval EFI_UNSUPPORTEDT The platform does not support the generation of soft timer interrupts.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // If the timer interrupt is enabled, then the registered handler will be invoked.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync Status = mLegacy8259->GetMask (mLegacy8259, NULL, NULL, &IRQMask, NULL);
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Invoke the registered handler
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // @bug : This does not handle missed timer interrupts
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync Initialize the Timer Architectural Protocol driver
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @param ImageHandle ImageHandle of the loaded driver
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @param SystemTable Pointer to the System Table
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @retval EFI_SUCCESS Timer Architectural Protocol created
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @retval EFI_OUT_OF_RESOURCES Not enough resources available to initialize driver.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @retval EFI_DEVICE_ERROR A device error occured attempting to initialize the driver.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Initialize the pointer to our notify function.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Make sure the Timer Architectural Protocol is not already installed in the system
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync ASSERT_PROTOCOL_ALREADY_INSTALLED (NULL, &gEfiTimerArchProtocolGuid);
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Find the CPU architectural protocol.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync Status = gBS->LocateProtocol (&gEfiCpuArchProtocolGuid, NULL, (VOID **) &mCpu);
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Find the Legacy8259 protocol.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync Status = gBS->LocateProtocol (&gEfiLegacy8259ProtocolGuid, NULL, (VOID **) &mLegacy8259);
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Force the timer to be disabled
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Get the interrupt vector number corresponding to IRQ0 from the 8259 driver
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync Status = mLegacy8259->GetVector (mLegacy8259, Efi8259Irq0, (UINT8 *) &TimerVector);
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Install interrupt handler for 8254 Timer #0 (ISA IRQ0)
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync Status = mCpu->RegisterInterruptHandler (mCpu, TimerVector, TimerInterruptHandler);
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Force the timer to be enabled at its default period
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync Status = TimerDriverSetTimerPeriod (&mTimer, DEFAULT_TIMER_TICK_DURATION);
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Install the Timer Architectural Protocol onto a new handle