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/** @file
Timer Architectural Protocol as defined in the DXE CIS
Copyright (c) 2005 - 2018, Intel Corporation. All rights reserved.<BR>
Copyright (c) 2019, Citrix Systems, Inc.
SPDX-License-Identifier: BSD-2-Clause-Patent
**/
#include "XenTimerDxe.h"
//
// The handle onto which the Timer Architectural Protocol will be installed
//
EFI_HANDLE mTimerHandle = NULL;
//
// The Timer Architectural Protocol that this driver produces
//
EFI_TIMER_ARCH_PROTOCOL mTimer = {
TimerDriverRegisterHandler,
TimerDriverSetTimerPeriod,
TimerDriverGetTimerPeriod,
TimerDriverGenerateSoftInterrupt
};
//
// Pointer to the CPU Architectural Protocol instance
//
EFI_CPU_ARCH_PROTOCOL *mCpu;
//
// The notification function to call on every timer interrupt.
// A bug in the compiler prevents us from initializing this here.
//
EFI_TIMER_NOTIFY mTimerNotifyFunction;
//
// The current period of the timer interrupt
//
volatile UINT64 mTimerPeriod = 0;
//
// Worker Functions
//
/**
Interrupt Handler.
@param InterruptType The type of interrupt that occurred
@param SystemContext A pointer to the system context when the interrupt occurred
**/
VOID
EFIAPI
TimerInterruptHandler (
IN EFI_EXCEPTION_TYPE InterruptType,
IN EFI_SYSTEM_CONTEXT SystemContext
)
{
EFI_TPL OriginalTPL;
OriginalTPL = gBS->RaiseTPL (TPL_HIGH_LEVEL);
if (mTimerNotifyFunction != NULL) {
//
// @bug : This does not handle missed timer interrupts
//
mTimerNotifyFunction (mTimerPeriod);
}
gBS->RestoreTPL (OriginalTPL);
DisableInterrupts ();
SendApicEoi ();
}
/**
This function registers the handler NotifyFunction so it is called every time
the timer interrupt fires. It also passes the amount of time since the last
handler call to the NotifyFunction. If NotifyFunction is NULL, then the
handler is unregistered. If the handler is registered, then EFI_SUCCESS is
returned. If the CPU does not support registering a timer interrupt handler,
then EFI_UNSUPPORTED is returned. If an attempt is made to register a handler
when a handler is already registered, then EFI_ALREADY_STARTED is returned.
If an attempt is made to unregister a handler when a handler is not registered,
then EFI_INVALID_PARAMETER is returned. If an error occurs attempting to
register the NotifyFunction with the timer interrupt, then EFI_DEVICE_ERROR
is returned.
@param This The EFI_TIMER_ARCH_PROTOCOL instance.
@param NotifyFunction The function to call when a timer interrupt fires. This
function executes at TPL_HIGH_LEVEL. The DXE Core will
register a handler for the timer interrupt, so it can know
how much time has passed. This information is used to
signal timer based events. NULL will unregister the handler.
@retval EFI_SUCCESS The timer handler was registered.
@retval EFI_UNSUPPORTED The platform does not support timer interrupts.
@retval EFI_ALREADY_STARTED NotifyFunction is not NULL, and a handler is already
registered.
@retval EFI_INVALID_PARAMETER NotifyFunction is NULL, and a handler was not
previously registered.
@retval EFI_DEVICE_ERROR The timer handler could not be registered.
**/
EFI_STATUS
EFIAPI
TimerDriverRegisterHandler (
IN EFI_TIMER_ARCH_PROTOCOL *This,
IN EFI_TIMER_NOTIFY NotifyFunction
)
{
//
// Check for invalid parameters
//
if (NotifyFunction == NULL && mTimerNotifyFunction == NULL) {
return EFI_INVALID_PARAMETER;
}
if (NotifyFunction != NULL && mTimerNotifyFunction != NULL) {
return EFI_ALREADY_STARTED;
}
mTimerNotifyFunction = NotifyFunction;
return EFI_SUCCESS;
}
/**
This function adjusts the period of timer interrupts to the value specified
by TimerPeriod. If the timer period is updated, then the selected timer
period is stored in EFI_TIMER.TimerPeriod, and EFI_SUCCESS is returned. If
the timer hardware is not programmable, then EFI_UNSUPPORTED is returned.
If an error occurs while attempting to update the timer period, then the
timer hardware will be put back in its state prior to this call, and
EFI_DEVICE_ERROR is returned. If TimerPeriod is 0, then the timer interrupt
is disabled. This is not the same as disabling the CPU's interrupts.
Instead, it must either turn off the timer hardware, or it must adjust the
interrupt controller so that a CPU interrupt is not generated when the timer
interrupt fires.
@param This The EFI_TIMER_ARCH_PROTOCOL instance.
@param TimerPeriod The rate to program the timer interrupt in 100 nS units. If
the timer hardware is not programmable, then EFI_UNSUPPORTED is
returned. If the timer is programmable, then the timer period
will be rounded up to the nearest timer period that is supported
by the timer hardware. If TimerPeriod is set to 0, then the
timer interrupts will be disabled.
@retval EFI_SUCCESS The timer period was changed.
@retval EFI_UNSUPPORTED The platform cannot change the period of the timer interrupt.
@retval EFI_DEVICE_ERROR The timer period could not be changed due to a device error.
**/
EFI_STATUS
EFIAPI
TimerDriverSetTimerPeriod (
IN EFI_TIMER_ARCH_PROTOCOL *This,
IN UINT64 TimerPeriod
)
{
UINT64 TimerCount;
UINT32 TimerFrequency;
UINT32 DivideValue = 1;
if (TimerPeriod == 0) {
//
// Disable timer interrupt for a TimerPeriod of 0
//
DisableApicTimerInterrupt();
} else {
TimerFrequency = PcdGet32(PcdFSBClock) / DivideValue;
//
// Convert TimerPeriod into local APIC counts
//
// TimerPeriod is in 100ns
// TimerPeriod/10000000 will be in seconds.
TimerCount = DivU64x32 (MultU64x32 (TimerPeriod, TimerFrequency),
10000000);
// Check for overflow
if (TimerCount > MAX_UINT32) {
TimerCount = MAX_UINT32;
/* TimerPeriod = (MAX_UINT32 / TimerFrequency) * 10000000; */
TimerPeriod = 429496730;
}
//
// Program the timer with the new count value
//
InitializeApicTimer(DivideValue, (UINT32)TimerCount, TRUE, LOCAL_APIC_TIMER_VECTOR);
//
// Enable timer interrupt
//
EnableApicTimerInterrupt();
}
//
// Save the new timer period
//
mTimerPeriod = TimerPeriod;
return EFI_SUCCESS;
}
/**
This function retrieves the period of timer interrupts in 100 ns units,
returns that value in TimerPeriod, and returns EFI_SUCCESS. If TimerPeriod
is NULL, then EFI_INVALID_PARAMETER is returned. If a TimerPeriod of 0 is
returned, then the timer is currently disabled.
@param This The EFI_TIMER_ARCH_PROTOCOL instance.
@param TimerPeriod A pointer to the timer period to retrieve in 100 ns units. If
0 is returned, then the timer is currently disabled.
@retval EFI_SUCCESS The timer period was returned in TimerPeriod.
@retval EFI_INVALID_PARAMETER TimerPeriod is NULL.
**/
EFI_STATUS
EFIAPI
TimerDriverGetTimerPeriod (
IN EFI_TIMER_ARCH_PROTOCOL *This,
OUT UINT64 *TimerPeriod
)
{
if (TimerPeriod == NULL) {
return EFI_INVALID_PARAMETER;
}
*TimerPeriod = mTimerPeriod;
return EFI_SUCCESS;
}
/**
This function generates a soft timer interrupt. If the platform does not support soft
timer interrupts, then EFI_UNSUPPORTED is returned. Otherwise, EFI_SUCCESS is returned.
If a handler has been registered through the EFI_TIMER_ARCH_PROTOCOL.RegisterHandler()
service, then a soft timer interrupt will be generated. If the timer interrupt is
enabled when this service is called, then the registered handler will be invoked. The
registered handler should not be able to distinguish a hardware-generated timer
interrupt from a software-generated timer interrupt.
@param This The EFI_TIMER_ARCH_PROTOCOL instance.
@retval EFI_SUCCESS The soft timer interrupt was generated.
@retval EFI_UNSUPPORTED The platform does not support the generation of soft timer interrupts.
**/
EFI_STATUS
EFIAPI
TimerDriverGenerateSoftInterrupt (
IN EFI_TIMER_ARCH_PROTOCOL *This
)
{
EFI_TPL OriginalTPL;
if (GetApicTimerInterruptState()) {
//
// Invoke the registered handler
//
OriginalTPL = gBS->RaiseTPL (TPL_HIGH_LEVEL);
if (mTimerNotifyFunction != NULL) {
//
// @bug : This does not handle missed timer interrupts
//
mTimerNotifyFunction (mTimerPeriod);
}
gBS->RestoreTPL (OriginalTPL);
} else {
return EFI_UNSUPPORTED;
}
return EFI_SUCCESS;
}
/**
Initialize the Timer Architectural Protocol driver
@param ImageHandle ImageHandle of the loaded driver
@param SystemTable Pointer to the System Table
@retval EFI_SUCCESS Timer Architectural Protocol created
@retval EFI_OUT_OF_RESOURCES Not enough resources available to initialize driver.
@retval EFI_DEVICE_ERROR A device error occurred attempting to initialize the driver.
**/
EFI_STATUS
EFIAPI
TimerDriverInitialize (
IN EFI_HANDLE ImageHandle,
IN EFI_SYSTEM_TABLE *SystemTable
)
{
EFI_STATUS Status;
//
// Initialize the pointer to our notify function.
//
mTimerNotifyFunction = NULL;
//
// Make sure the Timer Architectural Protocol is not already installed in the system
//
ASSERT_PROTOCOL_ALREADY_INSTALLED (NULL, &gEfiTimerArchProtocolGuid);
//
// Find the CPU architectural protocol.
//
Status = gBS->LocateProtocol (&gEfiCpuArchProtocolGuid, NULL, (VOID **) &mCpu);
ASSERT_EFI_ERROR (Status);
//
// Force the timer to be disabled
//
Status = TimerDriverSetTimerPeriod (&mTimer, 0);
ASSERT_EFI_ERROR (Status);
//
// Install interrupt handler for Local APIC Timer
//
Status = mCpu->RegisterInterruptHandler (mCpu, LOCAL_APIC_TIMER_VECTOR,
TimerInterruptHandler);
ASSERT_EFI_ERROR (Status);
//
// Force the timer to be enabled at its default period
//
Status = TimerDriverSetTimerPeriod (&mTimer, DEFAULT_TIMER_TICK_DURATION);
ASSERT_EFI_ERROR (Status);
//
// Install the Timer Architectural Protocol onto a new handle
//
Status = gBS->InstallMultipleProtocolInterfaces (
&mTimerHandle,
&gEfiTimerArchProtocolGuid, &mTimer,
NULL
);
ASSERT_EFI_ERROR (Status);
return Status;
}
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