OvmfPkg/XenTimerDxe/XenTimerDxe.c

   1 /** @file
   2   Timer Architectural Protocol as defined in the DXE CIS
   3
   4 Copyright (c) 2005 - 2018, Intel Corporation. All rights reserved.<BR>
   5 Copyright (c) 2019, Citrix Systems, Inc.
   6
   7 SPDX-License-Identifier: BSD-2-Clause-Patent
   8
   9 **/
  10
  11 #include "XenTimerDxe.h"
  12
  13 //
  14 // The handle onto which the Timer Architectural Protocol will be installed
  15 //
  16 EFI_HANDLE                mTimerHandle = NULL;
  17
  18 //
  19 // The Timer Architectural Protocol that this driver produces
  20 //
  21 EFI_TIMER_ARCH_PROTOCOL   mTimer = {
  22   TimerDriverRegisterHandler,
  23   TimerDriverSetTimerPeriod,
  24   TimerDriverGetTimerPeriod,
  25   TimerDriverGenerateSoftInterrupt
  26 };
  27
  28 //
  29 // Pointer to the CPU Architectural Protocol instance
  30 //
  31 EFI_CPU_ARCH_PROTOCOL     *mCpu;
  32
  33 //
  34 // The notification function to call on every timer interrupt.
  35 // A bug in the compiler prevents us from initializing this here.
  36 //
  37 EFI_TIMER_NOTIFY mTimerNotifyFunction;
  38
  39 //
  40 // The current period of the timer interrupt
  41 //
  42 volatile UINT64           mTimerPeriod = 0;
  43
  44 //
  45 // Worker Functions
  46 //
  47 /**
  48   Interrupt Handler.
  49
  50   @param InterruptType    The type of interrupt that occurred
  51   @param SystemContext    A pointer to the system context when the interrupt occurred
  52 **/
  53 VOID
  54 EFIAPI
  55 TimerInterruptHandler (
  56   IN EFI_EXCEPTION_TYPE   InterruptType,
  57   IN EFI_SYSTEM_CONTEXT   SystemContext
  58   )
  59 {
  60   EFI_TPL OriginalTPL;
  61
  62   OriginalTPL = gBS->RaiseTPL (TPL_HIGH_LEVEL);
  63
  64   SendApicEoi();
  65
  66   if (mTimerNotifyFunction != NULL) {
  67     //
  68     // @bug : This does not handle missed timer interrupts
  69     //
  70     mTimerNotifyFunction (mTimerPeriod);
  71   }
  72
  73   gBS->RestoreTPL (OriginalTPL);
  74 }
  75
  76 /**
  77
  78   This function registers the handler NotifyFunction so it is called every time
  79   the timer interrupt fires.  It also passes the amount of time since the last
  80   handler call to the NotifyFunction.  If NotifyFunction is NULL, then the
  81   handler is unregistered.  If the handler is registered, then EFI_SUCCESS is
  82   returned.  If the CPU does not support registering a timer interrupt handler,
  83   then EFI_UNSUPPORTED is returned.  If an attempt is made to register a handler
  84   when a handler is already registered, then EFI_ALREADY_STARTED is returned.
  85   If an attempt is made to unregister a handler when a handler is not registered,
  86   then EFI_INVALID_PARAMETER is returned.  If an error occurs attempting to
  87   register the NotifyFunction with the timer interrupt, then EFI_DEVICE_ERROR
  88   is returned.
  89
  90
  91   @param This             The EFI_TIMER_ARCH_PROTOCOL instance.
  92   @param NotifyFunction   The function to call when a timer interrupt fires.  This
  93                           function executes at TPL_HIGH_LEVEL.  The DXE Core will
  94                           register a handler for the timer interrupt, so it can know
  95                           how much time has passed.  This information is used to
  96                           signal timer based events.  NULL will unregister the handler.
  97
  98   @retval        EFI_SUCCESS            The timer handler was registered.
  99   @retval        EFI_UNSUPPORTED        The platform does not support timer interrupts.
 100   @retval        EFI_ALREADY_STARTED    NotifyFunction is not NULL, and a handler is already
 101                                         registered.
 102   @retval        EFI_INVALID_PARAMETER  NotifyFunction is NULL, and a handler was not
 103                                         previously registered.
 104   @retval        EFI_DEVICE_ERROR       The timer handler could not be registered.
 105
 106 **/
 107 EFI_STATUS
 108 EFIAPI
 109 TimerDriverRegisterHandler (
 110   IN EFI_TIMER_ARCH_PROTOCOL  *This,
 111   IN EFI_TIMER_NOTIFY         NotifyFunction
 112   )
 113 {
 114   //
 115   // Check for invalid parameters
 116   //
 117   if (NotifyFunction == NULL && mTimerNotifyFunction == NULL) {
 118     return EFI_INVALID_PARAMETER;
 119   }
 120
 121   if (NotifyFunction != NULL && mTimerNotifyFunction != NULL) {
 122     return EFI_ALREADY_STARTED;
 123   }
 124
 125   mTimerNotifyFunction = NotifyFunction;
 126
 127   return EFI_SUCCESS;
 128 }
 129
 130 /**
 131
 132   This function adjusts the period of timer interrupts to the value specified
 133   by TimerPeriod.  If the timer period is updated, then the selected timer
 134   period is stored in EFI_TIMER.TimerPeriod, and EFI_SUCCESS is returned.  If
 135   the timer hardware is not programmable, then EFI_UNSUPPORTED is returned.
 136   If an error occurs while attempting to update the timer period, then the
 137   timer hardware will be put back in its state prior to this call, and
 138   EFI_DEVICE_ERROR is returned.  If TimerPeriod is 0, then the timer interrupt
 139   is disabled.  This is not the same as disabling the CPU's interrupts.
 140   Instead, it must either turn off the timer hardware, or it must adjust the
 141   interrupt controller so that a CPU interrupt is not generated when the timer
 142   interrupt fires.
 143
 144
 145   @param This            The EFI_TIMER_ARCH_PROTOCOL instance.
 146   @param TimerPeriod     The rate to program the timer interrupt in 100 nS units.  If
 147                          the timer hardware is not programmable, then EFI_UNSUPPORTED is
 148                          returned.  If the timer is programmable, then the timer period
 149                          will be rounded up to the nearest timer period that is supported
 150                          by the timer hardware.  If TimerPeriod is set to 0, then the
 151                          timer interrupts will be disabled.
 152
 153   @retval        EFI_SUCCESS       The timer period was changed.
 154   @retval        EFI_UNSUPPORTED   The platform cannot change the period of the timer interrupt.
 155   @retval        EFI_DEVICE_ERROR  The timer period could not be changed due to a device error.
 156
 157 **/
 158 EFI_STATUS
 159 EFIAPI
 160 TimerDriverSetTimerPeriod (
 161   IN EFI_TIMER_ARCH_PROTOCOL  *This,
 162   IN UINT64                   TimerPeriod
 163   )
 164 {
 165   UINT64  TimerCount;
 166   UINT32  TimerFrequency;
 167   UINTN   DivideValue = 1;
 168
 169   if (TimerPeriod == 0) {
 170     //
 171     // Disable timer interrupt for a TimerPeriod of 0
 172     //
 173     DisableApicTimerInterrupt();
 174   } else {
 175     TimerFrequency = PcdGet32(PcdFSBClock) / DivideValue;
 176
 177     //
 178     // Convert TimerPeriod into local APIC counts
 179     //
 180     // TimerPeriod is in 100ns
 181     // TimerPeriod/10000000 will be in seconds.
 182     TimerCount = DivU64x32 (MultU64x32 (TimerPeriod, TimerFrequency),
 183                             10000000);
 184
 185     // Check for overflow
 186     if (TimerCount > MAX_UINT32) {
 187       TimerCount = MAX_UINT32;
 188       /* TimerPeriod = (MAX_UINT32 / TimerFrequency) * 10000000; */
 189       TimerPeriod = 429496730;
 190     }
 191
 192     //
 193     // Program the timer with the new count value
 194     //
 195     InitializeApicTimer(DivideValue, TimerCount, TRUE, LOCAL_APIC_TIMER_VECTOR);
 196
 197     //
 198     // Enable timer interrupt
 199     //
 200     EnableApicTimerInterrupt();
 201   }
 202   //
 203   // Save the new timer period
 204   //
 205   mTimerPeriod = TimerPeriod;
 206
 207   return EFI_SUCCESS;
 208 }
 209
 210 /**
 211
 212   This function retrieves the period of timer interrupts in 100 ns units,
 213   returns that value in TimerPeriod, and returns EFI_SUCCESS.  If TimerPeriod
 214   is NULL, then EFI_INVALID_PARAMETER is returned.  If a TimerPeriod of 0 is
 215   returned, then the timer is currently disabled.
 216
 217
 218   @param This            The EFI_TIMER_ARCH_PROTOCOL instance.
 219   @param TimerPeriod     A pointer to the timer period to retrieve in 100 ns units.  If
 220                          0 is returned, then the timer is currently disabled.
 221
 222   @retval EFI_SUCCESS            The timer period was returned in TimerPeriod.
 223   @retval EFI_INVALID_PARAMETER  TimerPeriod is NULL.
 224
 225 **/
 226 EFI_STATUS
 227 EFIAPI
 228 TimerDriverGetTimerPeriod (
 229   IN EFI_TIMER_ARCH_PROTOCOL   *This,
 230   OUT UINT64                   *TimerPeriod
 231   )
 232 {
 233   if (TimerPeriod == NULL) {
 234     return EFI_INVALID_PARAMETER;
 235   }
 236
 237   *TimerPeriod = mTimerPeriod;
 238
 239   return EFI_SUCCESS;
 240 }
 241
 242 /**
 243
 244   This function generates a soft timer interrupt. If the platform does not support soft
 245   timer interrupts, then EFI_UNSUPPORTED is returned. Otherwise, EFI_SUCCESS is returned.
 246   If a handler has been registered through the EFI_TIMER_ARCH_PROTOCOL.RegisterHandler()
 247   service, then a soft timer interrupt will be generated. If the timer interrupt is
 248   enabled when this service is called, then the registered handler will be invoked. The
 249   registered handler should not be able to distinguish a hardware-generated timer
 250   interrupt from a software-generated timer interrupt.
 251
 252
 253   @param This              The EFI_TIMER_ARCH_PROTOCOL instance.
 254
 255   @retval EFI_SUCCESS       The soft timer interrupt was generated.
 256   @retval EFI_UNSUPPORTED   The platform does not support the generation of soft timer interrupts.
 257
 258 **/
 259 EFI_STATUS
 260 EFIAPI
 261 TimerDriverGenerateSoftInterrupt (
 262   IN EFI_TIMER_ARCH_PROTOCOL  *This
 263   )
 264 {
 265   EFI_TPL     OriginalTPL;
 266
 267   if (GetApicTimerInterruptState()) {
 268     //
 269     // Invoke the registered handler
 270     //
 271     OriginalTPL = gBS->RaiseTPL (TPL_HIGH_LEVEL);
 272
 273     if (mTimerNotifyFunction != NULL) {
 274       //
 275       // @bug : This does not handle missed timer interrupts
 276       //
 277       mTimerNotifyFunction (mTimerPeriod);
 278     }
 279
 280     gBS->RestoreTPL (OriginalTPL);
 281   } else {
 282     return EFI_UNSUPPORTED;
 283   }
 284
 285   return EFI_SUCCESS;
 286 }
 287
 288 /**
 289   Initialize the Timer Architectural Protocol driver
 290
 291   @param ImageHandle     ImageHandle of the loaded driver
 292   @param SystemTable     Pointer to the System Table
 293
 294   @retval EFI_SUCCESS            Timer Architectural Protocol created
 295   @retval EFI_OUT_OF_RESOURCES   Not enough resources available to initialize driver.
 296   @retval EFI_DEVICE_ERROR       A device error occurred attempting to initialize the driver.
 297
 298 **/
 299 EFI_STATUS
 300 EFIAPI
 301 TimerDriverInitialize (
 302   IN EFI_HANDLE        ImageHandle,
 303   IN EFI_SYSTEM_TABLE  *SystemTable
 304   )
 305 {
 306   EFI_STATUS  Status;
 307
 308   //
 309   // Initialize the pointer to our notify function.
 310   //
 311   mTimerNotifyFunction = NULL;
 312
 313   //
 314   // Make sure the Timer Architectural Protocol is not already installed in the system
 315   //
 316   ASSERT_PROTOCOL_ALREADY_INSTALLED (NULL, &gEfiTimerArchProtocolGuid);
 317
 318   //
 319   // Find the CPU architectural protocol.
 320   //
 321   Status = gBS->LocateProtocol (&gEfiCpuArchProtocolGuid, NULL, (VOID **) &mCpu);
 322   ASSERT_EFI_ERROR (Status);
 323
 324   //
 325   // Force the timer to be disabled
 326   //
 327   Status = TimerDriverSetTimerPeriod (&mTimer, 0);
 328   ASSERT_EFI_ERROR (Status);
 329
 330   //
 331   // Install interrupt handler for Local APIC Timer
 332   //
 333   Status = mCpu->RegisterInterruptHandler (mCpu, LOCAL_APIC_TIMER_VECTOR,
 334                                            TimerInterruptHandler);
 335   ASSERT_EFI_ERROR (Status);
 336
 337   //
 338   // Force the timer to be enabled at its default period
 339   //
 340   Status = TimerDriverSetTimerPeriod (&mTimer, DEFAULT_TIMER_TICK_DURATION);
 341   ASSERT_EFI_ERROR (Status);
 342
 343   //
 344   // Install the Timer Architectural Protocol onto a new handle
 345   //
 346   Status = gBS->InstallMultipleProtocolInterfaces (
 347                   &mTimerHandle,
 348                   &gEfiTimerArchProtocolGuid, &mTimer,
 349                   NULL
 350                   );
 351   ASSERT_EFI_ERROR (Status);
 352
 353   return Status;
 354 }
 355