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   if (mTimerNotifyFunction != NULL) {
  65     //
  66     // @bug : This does not handle missed timer interrupts
  67     //
  68     mTimerNotifyFunction (mTimerPeriod);
  69   }
  70
  71   gBS->RestoreTPL (OriginalTPL);
  72
  73   DisableInterrupts ();
  74   SendApicEoi ();
  75 }
  76
  77 /**
  78
  79   This function registers the handler NotifyFunction so it is called every time
  80   the timer interrupt fires.  It also passes the amount of time since the last
  81   handler call to the NotifyFunction.  If NotifyFunction is NULL, then the
  82   handler is unregistered.  If the handler is registered, then EFI_SUCCESS is
  83   returned.  If the CPU does not support registering a timer interrupt handler,
  84   then EFI_UNSUPPORTED is returned.  If an attempt is made to register a handler
  85   when a handler is already registered, then EFI_ALREADY_STARTED is returned.
  86   If an attempt is made to unregister a handler when a handler is not registered,
  87   then EFI_INVALID_PARAMETER is returned.  If an error occurs attempting to
  88   register the NotifyFunction with the timer interrupt, then EFI_DEVICE_ERROR
  89   is returned.
  90
  91
  92   @param This             The EFI_TIMER_ARCH_PROTOCOL instance.
  93   @param NotifyFunction   The function to call when a timer interrupt fires.  This
  94                           function executes at TPL_HIGH_LEVEL.  The DXE Core will
  95                           register a handler for the timer interrupt, so it can know
  96                           how much time has passed.  This information is used to
  97                           signal timer based events.  NULL will unregister the handler.
  98
  99   @retval        EFI_SUCCESS            The timer handler was registered.
 100   @retval        EFI_UNSUPPORTED        The platform does not support timer interrupts.
 101   @retval        EFI_ALREADY_STARTED    NotifyFunction is not NULL, and a handler is already
 102                                         registered.
 103   @retval        EFI_INVALID_PARAMETER  NotifyFunction is NULL, and a handler was not
 104                                         previously registered.
 105   @retval        EFI_DEVICE_ERROR       The timer handler could not be registered.
 106
 107 **/
 108 EFI_STATUS
 109 EFIAPI
 110 TimerDriverRegisterHandler (
 111   IN EFI_TIMER_ARCH_PROTOCOL  *This,
 112   IN EFI_TIMER_NOTIFY         NotifyFunction
 113   )
 114 {
 115   //
 116   // Check for invalid parameters
 117   //
 118   if (NotifyFunction == NULL && mTimerNotifyFunction == NULL) {
 119     return EFI_INVALID_PARAMETER;
 120   }
 121
 122   if (NotifyFunction != NULL && mTimerNotifyFunction != NULL) {
 123     return EFI_ALREADY_STARTED;
 124   }
 125
 126   mTimerNotifyFunction = NotifyFunction;
 127
 128   return EFI_SUCCESS;
 129 }
 130
 131 /**
 132
 133   This function adjusts the period of timer interrupts to the value specified
 134   by TimerPeriod.  If the timer period is updated, then the selected timer
 135   period is stored in EFI_TIMER.TimerPeriod, and EFI_SUCCESS is returned.  If
 136   the timer hardware is not programmable, then EFI_UNSUPPORTED is returned.
 137   If an error occurs while attempting to update the timer period, then the
 138   timer hardware will be put back in its state prior to this call, and
 139   EFI_DEVICE_ERROR is returned.  If TimerPeriod is 0, then the timer interrupt
 140   is disabled.  This is not the same as disabling the CPU's interrupts.
 141   Instead, it must either turn off the timer hardware, or it must adjust the
 142   interrupt controller so that a CPU interrupt is not generated when the timer
 143   interrupt fires.
 144
 145
 146   @param This            The EFI_TIMER_ARCH_PROTOCOL instance.
 147   @param TimerPeriod     The rate to program the timer interrupt in 100 nS units.  If
 148                          the timer hardware is not programmable, then EFI_UNSUPPORTED is
 149                          returned.  If the timer is programmable, then the timer period
 150                          will be rounded up to the nearest timer period that is supported
 151                          by the timer hardware.  If TimerPeriod is set to 0, then the
 152                          timer interrupts will be disabled.
 153
 154   @retval        EFI_SUCCESS       The timer period was changed.
 155   @retval        EFI_UNSUPPORTED   The platform cannot change the period of the timer interrupt.
 156   @retval        EFI_DEVICE_ERROR  The timer period could not be changed due to a device error.
 157
 158 **/
 159 EFI_STATUS
 160 EFIAPI
 161 TimerDriverSetTimerPeriod (
 162   IN EFI_TIMER_ARCH_PROTOCOL  *This,
 163   IN UINT64                   TimerPeriod
 164   )
 165 {
 166   UINT64  TimerCount;
 167   UINT32  TimerFrequency;
 168   UINT32  DivideValue = 1;
 169
 170   if (TimerPeriod == 0) {
 171     //
 172     // Disable timer interrupt for a TimerPeriod of 0
 173     //
 174     DisableApicTimerInterrupt();
 175   } else {
 176     TimerFrequency = PcdGet32(PcdFSBClock) / DivideValue;
 177
 178     //
 179     // Convert TimerPeriod into local APIC counts
 180     //
 181     // TimerPeriod is in 100ns
 182     // TimerPeriod/10000000 will be in seconds.
 183     TimerCount = DivU64x32 (MultU64x32 (TimerPeriod, TimerFrequency),
 184                             10000000);
 185
 186     // Check for overflow
 187     if (TimerCount > MAX_UINT32) {
 188       TimerCount = MAX_UINT32;
 189       /* TimerPeriod = (MAX_UINT32 / TimerFrequency) * 10000000; */
 190       TimerPeriod = 429496730;
 191     }
 192
 193     //
 194     // Program the timer with the new count value
 195     //
 196     InitializeApicTimer(DivideValue, (UINT32)TimerCount, TRUE, LOCAL_APIC_TIMER_VECTOR);
 197
 198     //
 199     // Enable timer interrupt
 200     //
 201     EnableApicTimerInterrupt();
 202   }
 203   //
 204   // Save the new timer period
 205   //
 206   mTimerPeriod = TimerPeriod;
 207
 208   return EFI_SUCCESS;
 209 }
 210
 211 /**
 212
 213   This function retrieves the period of timer interrupts in 100 ns units,
 214   returns that value in TimerPeriod, and returns EFI_SUCCESS.  If TimerPeriod
 215   is NULL, then EFI_INVALID_PARAMETER is returned.  If a TimerPeriod of 0 is
 216   returned, then the timer is currently disabled.
 217
 218
 219   @param This            The EFI_TIMER_ARCH_PROTOCOL instance.
 220   @param TimerPeriod     A pointer to the timer period to retrieve in 100 ns units.  If
 221                          0 is returned, then the timer is currently disabled.
 222
 223   @retval EFI_SUCCESS            The timer period was returned in TimerPeriod.
 224   @retval EFI_INVALID_PARAMETER  TimerPeriod is NULL.
 225
 226 **/
 227 EFI_STATUS
 228 EFIAPI
 229 TimerDriverGetTimerPeriod (
 230   IN EFI_TIMER_ARCH_PROTOCOL   *This,
 231   OUT UINT64                   *TimerPeriod
 232   )
 233 {
 234   if (TimerPeriod == NULL) {
 235     return EFI_INVALID_PARAMETER;
 236   }
 237
 238   *TimerPeriod = mTimerPeriod;
 239
 240   return EFI_SUCCESS;
 241 }
 242
 243 /**
 244
 245   This function generates a soft timer interrupt. If the platform does not support soft
 246   timer interrupts, then EFI_UNSUPPORTED is returned. Otherwise, EFI_SUCCESS is returned.
 247   If a handler has been registered through the EFI_TIMER_ARCH_PROTOCOL.RegisterHandler()
 248   service, then a soft timer interrupt will be generated. If the timer interrupt is
 249   enabled when this service is called, then the registered handler will be invoked. The
 250   registered handler should not be able to distinguish a hardware-generated timer
 251   interrupt from a software-generated timer interrupt.
 252
 253
 254   @param This              The EFI_TIMER_ARCH_PROTOCOL instance.
 255
 256   @retval EFI_SUCCESS       The soft timer interrupt was generated.
 257   @retval EFI_UNSUPPORTED   The platform does not support the generation of soft timer interrupts.
 258
 259 **/
 260 EFI_STATUS
 261 EFIAPI
 262 TimerDriverGenerateSoftInterrupt (
 263   IN EFI_TIMER_ARCH_PROTOCOL  *This
 264   )
 265 {
 266   EFI_TPL     OriginalTPL;
 267
 268   if (GetApicTimerInterruptState()) {
 269     //
 270     // Invoke the registered handler
 271     //
 272     OriginalTPL = gBS->RaiseTPL (TPL_HIGH_LEVEL);
 273
 274     if (mTimerNotifyFunction != NULL) {
 275       //
 276       // @bug : This does not handle missed timer interrupts
 277       //
 278       mTimerNotifyFunction (mTimerPeriod);
 279     }
 280
 281     gBS->RestoreTPL (OriginalTPL);
 282   } else {
 283     return EFI_UNSUPPORTED;
 284   }
 285
 286   return EFI_SUCCESS;
 287 }
 288
 289 /**
 290   Initialize the Timer Architectural Protocol driver
 291
 292   @param ImageHandle     ImageHandle of the loaded driver
 293   @param SystemTable     Pointer to the System Table
 294
 295   @retval EFI_SUCCESS            Timer Architectural Protocol created
 296   @retval EFI_OUT_OF_RESOURCES   Not enough resources available to initialize driver.
 297   @retval EFI_DEVICE_ERROR       A device error occurred attempting to initialize the driver.
 298
 299 **/
 300 EFI_STATUS
 301 EFIAPI
 302 TimerDriverInitialize (
 303   IN EFI_HANDLE        ImageHandle,
 304   IN EFI_SYSTEM_TABLE  *SystemTable
 305   )
 306 {
 307   EFI_STATUS  Status;
 308
 309   //
 310   // Initialize the pointer to our notify function.
 311   //
 312   mTimerNotifyFunction = NULL;
 313
 314   //
 315   // Make sure the Timer Architectural Protocol is not already installed in the system
 316   //
 317   ASSERT_PROTOCOL_ALREADY_INSTALLED (NULL, &gEfiTimerArchProtocolGuid);
 318
 319   //
 320   // Find the CPU architectural protocol.
 321   //
 322   Status = gBS->LocateProtocol (&gEfiCpuArchProtocolGuid, NULL, (VOID **) &mCpu);
 323   ASSERT_EFI_ERROR (Status);
 324
 325   //
 326   // Force the timer to be disabled
 327   //
 328   Status = TimerDriverSetTimerPeriod (&mTimer, 0);
 329   ASSERT_EFI_ERROR (Status);
 330
 331   //
 332   // Install interrupt handler for Local APIC Timer
 333   //
 334   Status = mCpu->RegisterInterruptHandler (mCpu, LOCAL_APIC_TIMER_VECTOR,
 335                                            TimerInterruptHandler);
 336   ASSERT_EFI_ERROR (Status);
 337
 338   //
 339   // Force the timer to be enabled at its default period
 340   //
 341   Status = TimerDriverSetTimerPeriod (&mTimer, DEFAULT_TIMER_TICK_DURATION);
 342   ASSERT_EFI_ERROR (Status);
 343
 344   //
 345   // Install the Timer Architectural Protocol onto a new handle
 346   //
 347   Status = gBS->InstallMultipleProtocolInterfaces (
 348                   &mTimerHandle,
 349                   &gEfiTimerArchProtocolGuid, &mTimer,
 350                   NULL
 351                   );
 352   ASSERT_EFI_ERROR (Status);
 353
 354   return Status;
 355 }
 356