PcAtChipsetPkg/8254TimerDxe/Timer.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 This program and the accompanying materials
   6 are licensed and made available under the terms and conditions of the BSD License
   7 which accompanies this distribution.  The full text of the license may be found at
   8 http://opensource.org/licenses/bsd-license.php
   9
  10 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  11 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  12
  13 **/
  14
  15 #include "Timer.h"
  16
  17 //
  18 // The handle onto which the Timer Architectural Protocol will be installed
  19 //
  20 EFI_HANDLE                mTimerHandle = NULL;
  21
  22 //
  23 // The Timer Architectural Protocol that this driver produces
  24 //
  25 EFI_TIMER_ARCH_PROTOCOL   mTimer = {
  26   TimerDriverRegisterHandler,
  27   TimerDriverSetTimerPeriod,
  28   TimerDriverGetTimerPeriod,
  29   TimerDriverGenerateSoftInterrupt
  30 };
  31
  32 //
  33 // Pointer to the CPU Architectural Protocol instance
  34 //
  35 EFI_CPU_ARCH_PROTOCOL     *mCpu;
  36
  37 //
  38 // Pointer to the Legacy 8259 Protocol instance
  39 //
  40 EFI_LEGACY_8259_PROTOCOL  *mLegacy8259;
  41
  42 //
  43 // The notification function to call on every timer interrupt.
  44 // A bug in the compiler prevents us from initializing this here.
  45 //
  46 EFI_TIMER_NOTIFY mTimerNotifyFunction;
  47
  48 //
  49 // The current period of the timer interrupt
  50 //
  51 volatile UINT64           mTimerPeriod = 0;
  52
  53 //
  54 // Worker Functions
  55 //
  56 /**
  57   Sets the counter value for Timer #0 in a legacy 8254 timer.
  58
  59   @param Count    The 16-bit counter value to program into Timer #0 of the legacy 8254 timer.
  60 **/
  61 VOID
  62 SetPitCount (
  63   IN UINT16  Count
  64   )
  65 {
  66   IoWrite8 (TIMER_CONTROL_PORT, 0x36);
  67   IoWrite8 (TIMER0_COUNT_PORT, (UINT8)(Count & 0xff));
  68   IoWrite8 (TIMER0_COUNT_PORT, (UINT8)((Count >> 8) & 0xff));
  69 }
  70
  71 /**
  72   8254 Timer #0 Interrupt Handler.
  73
  74   @param InterruptType    The type of interrupt that occurred
  75   @param SystemContext    A pointer to the system context when the interrupt occurred
  76 **/
  77 VOID
  78 EFIAPI
  79 TimerInterruptHandler (
  80   IN EFI_EXCEPTION_TYPE   InterruptType,
  81   IN EFI_SYSTEM_CONTEXT   SystemContext
  82   )
  83 {
  84   EFI_TPL OriginalTPL;
  85
  86   OriginalTPL = gBS->RaiseTPL (TPL_HIGH_LEVEL);
  87
  88   mLegacy8259->EndOfInterrupt (mLegacy8259, Efi8259Irq0);
  89
  90   if (mTimerNotifyFunction != NULL) {
  91     //
  92     // @bug : This does not handle missed timer interrupts
  93     //
  94     mTimerNotifyFunction (mTimerPeriod);
  95   }
  96
  97   gBS->RestoreTPL (OriginalTPL);
  98 }
  99
 100 /**
 101
 102   This function registers the handler NotifyFunction so it is called every time
 103   the timer interrupt fires.  It also passes the amount of time since the last
 104   handler call to the NotifyFunction.  If NotifyFunction is NULL, then the
 105   handler is unregistered.  If the handler is registered, then EFI_SUCCESS is
 106   returned.  If the CPU does not support registering a timer interrupt handler,
 107   then EFI_UNSUPPORTED is returned.  If an attempt is made to register a handler
 108   when a handler is already registered, then EFI_ALREADY_STARTED is returned.
 109   If an attempt is made to unregister a handler when a handler is not registered,
 110   then EFI_INVALID_PARAMETER is returned.  If an error occurs attempting to
 111   register the NotifyFunction with the timer interrupt, then EFI_DEVICE_ERROR
 112   is returned.
 113
 114
 115   @param This             The EFI_TIMER_ARCH_PROTOCOL instance.
 116   @param NotifyFunction   The function to call when a timer interrupt fires.  This
 117                           function executes at TPL_HIGH_LEVEL.  The DXE Core will
 118                           register a handler for the timer interrupt, so it can know
 119                           how much time has passed.  This information is used to
 120                           signal timer based events.  NULL will unregister the handler.
 121
 122   @retval        EFI_SUCCESS            The timer handler was registered.
 123   @retval        EFI_UNSUPPORTED        The platform does not support timer interrupts.
 124   @retval        EFI_ALREADY_STARTED    NotifyFunction is not NULL, and a handler is already
 125                                         registered.
 126   @retval        EFI_INVALID_PARAMETER  NotifyFunction is NULL, and a handler was not
 127                                         previously registered.
 128   @retval        EFI_DEVICE_ERROR       The timer handler could not be registered.
 129
 130 **/
 131 EFI_STATUS
 132 EFIAPI
 133 TimerDriverRegisterHandler (
 134   IN EFI_TIMER_ARCH_PROTOCOL  *This,
 135   IN EFI_TIMER_NOTIFY         NotifyFunction
 136   )
 137 {
 138   //
 139   // Check for invalid parameters
 140   //
 141   if (NotifyFunction == NULL && mTimerNotifyFunction == NULL) {
 142     return EFI_INVALID_PARAMETER;
 143   }
 144
 145   if (NotifyFunction != NULL && mTimerNotifyFunction != NULL) {
 146     return EFI_ALREADY_STARTED;
 147   }
 148
 149   mTimerNotifyFunction = NotifyFunction;
 150
 151   return EFI_SUCCESS;
 152 }
 153
 154 /**
 155
 156   This function adjusts the period of timer interrupts to the value specified
 157   by TimerPeriod.  If the timer period is updated, then the selected timer
 158   period is stored in EFI_TIMER.TimerPeriod, and EFI_SUCCESS is returned.  If
 159   the timer hardware is not programmable, then EFI_UNSUPPORTED is returned.
 160   If an error occurs while attempting to update the timer period, then the
 161   timer hardware will be put back in its state prior to this call, and
 162   EFI_DEVICE_ERROR is returned.  If TimerPeriod is 0, then the timer interrupt
 163   is disabled.  This is not the same as disabling the CPU's interrupts.
 164   Instead, it must either turn off the timer hardware, or it must adjust the
 165   interrupt controller so that a CPU interrupt is not generated when the timer
 166   interrupt fires.
 167
 168
 169   @param This            The EFI_TIMER_ARCH_PROTOCOL instance.
 170   @param TimerPeriod     The rate to program the timer interrupt in 100 nS units.  If
 171                          the timer hardware is not programmable, then EFI_UNSUPPORTED is
 172                          returned.  If the timer is programmable, then the timer period
 173                          will be rounded up to the nearest timer period that is supported
 174                          by the timer hardware.  If TimerPeriod is set to 0, then the
 175                          timer interrupts will be disabled.
 176
 177   @retval        EFI_SUCCESS       The timer period was changed.
 178   @retval        EFI_UNSUPPORTED   The platform cannot change the period of the timer interrupt.
 179   @retval        EFI_DEVICE_ERROR  The timer period could not be changed due to a device error.
 180
 181 **/
 182 EFI_STATUS
 183 EFIAPI
 184 TimerDriverSetTimerPeriod (
 185   IN EFI_TIMER_ARCH_PROTOCOL  *This,
 186   IN UINT64                   TimerPeriod
 187   )
 188 {
 189   UINT64  TimerCount;
 190
 191   //
 192   //  The basic clock is 1.19318 MHz or 0.119318 ticks per 100 ns.
 193   //  TimerPeriod * 0.119318 = 8254 timer divisor. Using integer arithmetic
 194   //  TimerCount = (TimerPeriod * 119318)/1000000.
 195   //
 196   //  Round up to next highest integer. This guarantees that the timer is
 197   //  equal to or slightly longer than the requested time.
 198   //  TimerCount = ((TimerPeriod * 119318) + 500000)/1000000
 199   //
 200   // Note that a TimerCount of 0 is equivalent to a count of 65,536
 201   //
 202   // Since TimerCount is limited to 16 bits for IA32, TimerPeriod is limited
 203   // to 20 bits.
 204   //
 205   if (TimerPeriod == 0) {
 206     //
 207     // Disable timer interrupt for a TimerPeriod of 0
 208     //
 209     mLegacy8259->DisableIrq (mLegacy8259, Efi8259Irq0);
 210   } else {
 211
 212     //
 213     // Convert TimerPeriod into 8254 counts
 214     //
 215     TimerCount = DivU64x32 (MultU64x32 (119318, (UINT32) TimerPeriod) + 500000, 1000000);
 216
 217     //
 218     // Check for overflow
 219     //
 220     if (TimerCount >= 65536) {
 221       TimerCount = 0;
 222       TimerPeriod = MAX_TIMER_TICK_DURATION;
 223     }
 224     //
 225     // Program the 8254 timer with the new count value
 226     //
 227     SetPitCount ((UINT16) TimerCount);
 228
 229     //
 230     // Enable timer interrupt
 231     //
 232     mLegacy8259->EnableIrq (mLegacy8259, Efi8259Irq0, FALSE);
 233   }
 234   //
 235   // Save the new timer period
 236   //
 237   mTimerPeriod = TimerPeriod;
 238
 239   return EFI_SUCCESS;
 240 }
 241
 242 /**
 243
 244   This function retrieves the period of timer interrupts in 100 ns units,
 245   returns that value in TimerPeriod, and returns EFI_SUCCESS.  If TimerPeriod
 246   is NULL, then EFI_INVALID_PARAMETER is returned.  If a TimerPeriod of 0 is
 247   returned, then the timer is currently disabled.
 248
 249
 250   @param This            The EFI_TIMER_ARCH_PROTOCOL instance.
 251   @param TimerPeriod     A pointer to the timer period to retrieve in 100 ns units.  If
 252                          0 is returned, then the timer is currently disabled.
 253
 254   @retval EFI_SUCCESS            The timer period was returned in TimerPeriod.
 255   @retval EFI_INVALID_PARAMETER  TimerPeriod is NULL.
 256
 257 **/
 258 EFI_STATUS
 259 EFIAPI
 260 TimerDriverGetTimerPeriod (
 261   IN EFI_TIMER_ARCH_PROTOCOL   *This,
 262   OUT UINT64                   *TimerPeriod
 263   )
 264 {
 265   if (TimerPeriod == NULL) {
 266     return EFI_INVALID_PARAMETER;
 267   }
 268
 269   *TimerPeriod = mTimerPeriod;
 270
 271   return EFI_SUCCESS;
 272 }
 273
 274 /**
 275
 276   This function generates a soft timer interrupt. If the platform does not support soft
 277   timer interrupts, then EFI_UNSUPPORTED is returned. Otherwise, EFI_SUCCESS is returned.
 278   If a handler has been registered through the EFI_TIMER_ARCH_PROTOCOL.RegisterHandler()
 279   service, then a soft timer interrupt will be generated. If the timer interrupt is
 280   enabled when this service is called, then the registered handler will be invoked. The
 281   registered handler should not be able to distinguish a hardware-generated timer
 282   interrupt from a software-generated timer interrupt.
 283
 284
 285   @param This              The EFI_TIMER_ARCH_PROTOCOL instance.
 286
 287   @retval EFI_SUCCESS       The soft timer interrupt was generated.
 288   @retval EFI_UNSUPPORTED   The platform does not support the generation of soft timer interrupts.
 289
 290 **/
 291 EFI_STATUS
 292 EFIAPI
 293 TimerDriverGenerateSoftInterrupt (
 294   IN EFI_TIMER_ARCH_PROTOCOL  *This
 295   )
 296 {
 297   EFI_STATUS  Status;
 298   UINT16      IRQMask;
 299   EFI_TPL     OriginalTPL;
 300
 301   //
 302   // If the timer interrupt is enabled, then the registered handler will be invoked.
 303   //
 304   Status = mLegacy8259->GetMask (mLegacy8259, NULL, NULL, &IRQMask, NULL);
 305   ASSERT_EFI_ERROR (Status);
 306   if ((IRQMask & 0x1) == 0) {
 307     //
 308     // Invoke the registered handler
 309     //
 310     OriginalTPL = gBS->RaiseTPL (TPL_HIGH_LEVEL);
 311
 312     if (mTimerNotifyFunction != NULL) {
 313       //
 314       // @bug : This does not handle missed timer interrupts
 315       //
 316       mTimerNotifyFunction (mTimerPeriod);
 317     }
 318
 319     gBS->RestoreTPL (OriginalTPL);
 320   } else {
 321     return EFI_UNSUPPORTED;
 322   }
 323
 324   return EFI_SUCCESS;
 325 }
 326
 327 /**
 328   Initialize the Timer Architectural Protocol driver
 329
 330   @param ImageHandle     ImageHandle of the loaded driver
 331   @param SystemTable     Pointer to the System Table
 332
 333   @retval EFI_SUCCESS            Timer Architectural Protocol created
 334   @retval EFI_OUT_OF_RESOURCES   Not enough resources available to initialize driver.
 335   @retval EFI_DEVICE_ERROR       A device error occurred attempting to initialize the driver.
 336
 337 **/
 338 EFI_STATUS
 339 EFIAPI
 340 TimerDriverInitialize (
 341   IN EFI_HANDLE        ImageHandle,
 342   IN EFI_SYSTEM_TABLE  *SystemTable
 343   )
 344 {
 345   EFI_STATUS  Status;
 346   UINT32      TimerVector;
 347
 348   //
 349   // Initialize the pointer to our notify function.
 350   //
 351   mTimerNotifyFunction = NULL;
 352
 353   //
 354   // Make sure the Timer Architectural Protocol is not already installed in the system
 355   //
 356   ASSERT_PROTOCOL_ALREADY_INSTALLED (NULL, &gEfiTimerArchProtocolGuid);
 357
 358   //
 359   // Find the CPU architectural protocol.
 360   //
 361   Status = gBS->LocateProtocol (&gEfiCpuArchProtocolGuid, NULL, (VOID **) &mCpu);
 362   ASSERT_EFI_ERROR (Status);
 363
 364   //
 365   // Find the Legacy8259 protocol.
 366   //
 367   Status = gBS->LocateProtocol (&gEfiLegacy8259ProtocolGuid, NULL, (VOID **) &mLegacy8259);
 368   ASSERT_EFI_ERROR (Status);
 369
 370   //
 371   // Force the timer to be disabled
 372   //
 373   Status = TimerDriverSetTimerPeriod (&mTimer, 0);
 374   ASSERT_EFI_ERROR (Status);
 375
 376   //
 377   // Get the interrupt vector number corresponding to IRQ0 from the 8259 driver
 378   //
 379   TimerVector = 0;
 380   Status      = mLegacy8259->GetVector (mLegacy8259, Efi8259Irq0, (UINT8 *) &TimerVector);
 381   ASSERT_EFI_ERROR (Status);
 382
 383   //
 384   // Install interrupt handler for 8254 Timer #0 (ISA IRQ0)
 385   //
 386   Status = mCpu->RegisterInterruptHandler (mCpu, TimerVector, TimerInterruptHandler);
 387   ASSERT_EFI_ERROR (Status);
 388
 389   //
 390   // Force the timer to be enabled at its default period
 391   //
 392   Status = TimerDriverSetTimerPeriod (&mTimer, DEFAULT_TIMER_TICK_DURATION);
 393   ASSERT_EFI_ERROR (Status);
 394
 395   //
 396   // Install the Timer Architectural Protocol onto a new handle
 397   //
 398   Status = gBS->InstallMultipleProtocolInterfaces (
 399                   &mTimerHandle,
 400                   &gEfiTimerArchProtocolGuid, &mTimer,
 401                   NULL
 402                   );
 403   ASSERT_EFI_ERROR (Status);
 404
 405   return Status;
 406 }
 407