[edk2-devel] [PATCH v3 31/35] OvmfPkg/OvmfXen: Introduce XenTimerDxe
Anthony PERARD
anthony.perard at citrix.com
Thu Jul 4 14:42:29 UTC 2019
"PcAtChipsetPkg/8254TimerDxe" is replaced with a Xen-specific
EFI_TIMER_ARCH_PROTOCOL implementation. Also remove
8259InterruptControllerDxe as it is not used anymore.
This Timer uses the local APIC timer as time source as it can work on
both a Xen PVH guest and an HVM one.
Based on the "PcAtChipsetPkg/8254TimerDxe" implementation.
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1689
Signed-off-by: Anthony PERARD <anthony.perard at citrix.com>
---
Notes:
v3:
- rebased, SPDX, copyright
v2:
- Use InitializeApicTimer instead of WriteLocalApicReg
- rework comments (remove many that don't apply)
- remove unused includes, and libs
- have a macro to the timervector.
- cleanup, copyright
- rework calculation of TimerCount, value to be use by the APIC timer
- check for overflow of TimerPeriod, with the apic timer, the period can
be up to about 42s on Xen (or even higher by changing the DivideValue).
OvmfPkg/OvmfXen.dsc | 3 +-
OvmfPkg/OvmfXen.fdf | 3 +-
OvmfPkg/XenTimerDxe/XenTimerDxe.inf | 42 ++++
OvmfPkg/XenTimerDxe/XenTimerDxe.h | 177 ++++++++++++++
OvmfPkg/XenTimerDxe/XenTimerDxe.c | 355 ++++++++++++++++++++++++++++
5 files changed, 576 insertions(+), 4 deletions(-)
create mode 100644 OvmfPkg/XenTimerDxe/XenTimerDxe.inf
create mode 100644 OvmfPkg/XenTimerDxe/XenTimerDxe.h
create mode 100644 OvmfPkg/XenTimerDxe/XenTimerDxe.c
diff --git a/OvmfPkg/OvmfXen.dsc b/OvmfPkg/OvmfXen.dsc
index bc6b6602c6..1ecae3fb45 100644
--- a/OvmfPkg/OvmfXen.dsc
+++ b/OvmfPkg/OvmfXen.dsc
@@ -547,10 +547,9 @@ [Components]
MdeModulePkg/Universal/SecurityStubDxe/SecurityStubDxe.inf
MdeModulePkg/Universal/EbcDxe/EbcDxe.inf
- OvmfPkg/8259InterruptControllerDxe/8259.inf
+ OvmfPkg/XenTimerDxe/XenTimerDxe.inf
UefiCpuPkg/CpuIo2Dxe/CpuIo2Dxe.inf
UefiCpuPkg/CpuDxe/CpuDxe.inf
- OvmfPkg/8254TimerDxe/8254Timer.inf
OvmfPkg/IncompatiblePciDeviceSupportDxe/IncompatiblePciDeviceSupport.inf
OvmfPkg/PciHotPlugInitDxe/PciHotPlugInit.inf
MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciHostBridgeDxe.inf {
diff --git a/OvmfPkg/OvmfXen.fdf b/OvmfPkg/OvmfXen.fdf
index 49997fee9b..fa0830a324 100644
--- a/OvmfPkg/OvmfXen.fdf
+++ b/OvmfPkg/OvmfXen.fdf
@@ -298,10 +298,9 @@ [FV.DXEFV]
INF MdeModulePkg/Core/RuntimeDxe/RuntimeDxe.inf
INF MdeModulePkg/Universal/SecurityStubDxe/SecurityStubDxe.inf
INF MdeModulePkg/Universal/EbcDxe/EbcDxe.inf
-INF OvmfPkg/8259InterruptControllerDxe/8259.inf
+INF OvmfPkg/XenTimerDxe/XenTimerDxe.inf
INF UefiCpuPkg/CpuIo2Dxe/CpuIo2Dxe.inf
INF UefiCpuPkg/CpuDxe/CpuDxe.inf
-INF OvmfPkg/8254TimerDxe/8254Timer.inf
INF OvmfPkg/IncompatiblePciDeviceSupportDxe/IncompatiblePciDeviceSupport.inf
INF OvmfPkg/PciHotPlugInitDxe/PciHotPlugInit.inf
INF MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciHostBridgeDxe.inf
diff --git a/OvmfPkg/XenTimerDxe/XenTimerDxe.inf b/OvmfPkg/XenTimerDxe/XenTimerDxe.inf
new file mode 100644
index 0000000000..add1d01bbf
--- /dev/null
+++ b/OvmfPkg/XenTimerDxe/XenTimerDxe.inf
@@ -0,0 +1,42 @@
+## @file
+# Local APIC timer driver that provides Timer Arch protocol.
+#
+# Copyright (c) 2005 - 2019, Intel Corporation. All rights reserved.<BR>
+# Copyright (c) 2019, Citrix Systems, Inc.
+#
+# SPDX-License-Identifier: BSD-2-Clause-Patent
+#
+##
+
+[Defines]
+ INF_VERSION = 0x00010005
+ BASE_NAME = XenTimerDxe
+ FILE_GUID = 52fe8196-f9de-4d07-b22f-51f77a0e7c41
+ MODULE_TYPE = DXE_DRIVER
+ VERSION_STRING = 1.0
+
+ ENTRY_POINT = TimerDriverInitialize
+
+[Packages]
+ MdePkg/MdePkg.dec
+ UefiCpuPkg/UefiCpuPkg.dec
+ OvmfPkg/OvmfPkg.dec
+
+[LibraryClasses]
+ UefiBootServicesTableLib
+ BaseLib
+ DebugLib
+ UefiDriverEntryPoint
+ LocalApicLib
+
+[Sources]
+ XenTimerDxe.h
+ XenTimerDxe.c
+
+[Protocols]
+ gEfiCpuArchProtocolGuid ## CONSUMES
+ gEfiTimerArchProtocolGuid ## PRODUCES
+[Pcd]
+ gEfiMdePkgTokenSpaceGuid.PcdFSBClock ## CONSUMES
+[Depex]
+ gEfiCpuArchProtocolGuid
diff --git a/OvmfPkg/XenTimerDxe/XenTimerDxe.h b/OvmfPkg/XenTimerDxe/XenTimerDxe.h
new file mode 100644
index 0000000000..e0a3d95fd0
--- /dev/null
+++ b/OvmfPkg/XenTimerDxe/XenTimerDxe.h
@@ -0,0 +1,177 @@
+/** @file
+ Private data structures
+
+Copyright (c) 2005 - 2018, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2019, Citrix Systems, Inc.
+
+SPDX-License-Identifier: BSD-2-Clause-Patent
+**/
+
+#ifndef _TIMER_H_
+#define _TIMER_H_
+
+#include <PiDxe.h>
+
+#include <Protocol/Cpu.h>
+#include <Protocol/Timer.h>
+
+#include <Register/LocalApic.h>
+
+#include <Library/UefiBootServicesTableLib.h>
+#include <Library/BaseLib.h>
+#include <Library/DebugLib.h>
+#include <Library/LocalApicLib.h>
+#include <Library/PcdLib.h>
+
+// The default timer tick duration is set to 10 ms = 100000 100 ns units
+//
+#define DEFAULT_TIMER_TICK_DURATION 100000
+
+//
+// The Timer Vector use for interrupt
+//
+#define LOCAL_APIC_TIMER_VECTOR 32
+
+//
+// Function Prototypes
+//
+/**
+ 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
+ )
+;
+
+/**
+
+ 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 NotifyFunction 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
+TimerDriverRegisterHandler (
+ IN EFI_TIMER_ARCH_PROTOCOL *This,
+ IN EFI_TIMER_NOTIFY NotifyFunction
+ )
+;
+
+/**
+
+ 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
+ )
+;
+
+/**
+
+ 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
+ )
+;
+
+/**
+
+ 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
+ )
+;
+
+#endif
diff --git a/OvmfPkg/XenTimerDxe/XenTimerDxe.c b/OvmfPkg/XenTimerDxe/XenTimerDxe.c
new file mode 100644
index 0000000000..9f9e04766c
--- /dev/null
+++ b/OvmfPkg/XenTimerDxe/XenTimerDxe.c
@@ -0,0 +1,355 @@
+/** @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);
+
+ SendApicEoi();
+
+ if (mTimerNotifyFunction != NULL) {
+ //
+ // @bug : This does not handle missed timer interrupts
+ //
+ mTimerNotifyFunction (mTimerPeriod);
+ }
+
+ gBS->RestoreTPL (OriginalTPL);
+}
+
+/**
+
+ 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;
+ UINTN 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, 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;
+}
+
--
Anthony PERARD
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