PcAtChipsetPkg/8254TimerDxe/Timer.c

   1 /*++
   2
   3 Copyright (c) 2005 - 2006, Intel Corporation
   4 All rights reserved. This program and the accompanying materials
   5 are licensed and made available under the terms and conditions of the BSD License
   6 which accompanies this distribution.  The full text of the license may be found at
   7 http://opensource.org/licenses/bsd-license.php
   8
   9 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  10 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  11
  12
  13 Module Name:
  14
  15  Timer.c
  16
  17 Abstract:
  18
  19   Timer Architectural Protocol as defined in the DXE CIS
  20
  21 --*/
  22
  23 #include "Timer.h"
  24
  25 //
  26 // The handle onto which the Timer Architectural Protocol will be installed
  27 //
  28 EFI_HANDLE                mTimerHandle = NULL;
  29
  30 //
  31 // The Timer Architectural Protocol that this driver produces
  32 //
  33 EFI_TIMER_ARCH_PROTOCOL   mTimer = {
  34   TimerDriverRegisterHandler,
  35   TimerDriverSetTimerPeriod,
  36   TimerDriverGetTimerPeriod,
  37   TimerDriverGenerateSoftInterrupt
  38 };
  39
  40 //
  41 // Pointer to the CPU Architectural Protocol instance
  42 //
  43 EFI_CPU_ARCH_PROTOCOL     *mCpu;
  44
  45 //
  46 // Pointer to the Legacy 8259 Protocol instance
  47 //
  48 EFI_LEGACY_8259_PROTOCOL  *mLegacy8259;
  49
  50 //
  51 // The notification function to call on every timer interrupt.
  52 // A bug in the compiler prevents us from initializing this here.
  53 //
  54 EFI_TIMER_NOTIFY mTimerNotifyFunction;
  55
  56 //
  57 // The current period of the timer interrupt
  58 //
  59 volatile UINT64           mTimerPeriod = 0;
  60
  61 //
  62 // Worker Functions
  63 //
  64 VOID
  65 SetPitCount (
  66   IN UINT16  Count
  67   )
  68 /*++
  69
  70 Routine Description:
  71
  72   Sets the counter value for Timer #0 in a legacy 8254 timer.
  73
  74 Arguments:
  75
  76   Count - The 16-bit counter value to program into Timer #0 of the legacy 8254 timer.
  77
  78 Returns:
  79
  80   None
  81
  82 --*/
  83 {
  84   IoWrite8 (TIMER_CONTROL_PORT, 0x36);
  85   IoWrite8 (TIMER0_COUNT_PORT, (UINT8)(Count & 0xff));
  86   IoWrite8 (TIMER0_COUNT_PORT, (UINT8)((Count >> 8) & 0xff));
  87 }
  88
  89 VOID
  90 EFIAPI
  91 TimerInterruptHandler (
  92   IN EFI_EXCEPTION_TYPE   InterruptType,
  93   IN EFI_SYSTEM_CONTEXT   SystemContext
  94   )
  95 /*++
  96
  97 Routine Description:
  98
  99   8254 Timer #0 Interrupt Handler
 100
 101 Arguments:
 102
 103   InterruptType - The type of interrupt that occured
 104
 105   SystemContext - A pointer to the system context when the interrupt occured
 106
 107 Returns:
 108
 109   None
 110
 111 --*/
 112 {
 113   EFI_TPL OriginalTPL;
 114
 115   OriginalTPL = gBS->RaiseTPL (TPL_HIGH_LEVEL);
 116
 117   mLegacy8259->EndOfInterrupt (mLegacy8259, Efi8259Irq0);
 118
 119   if (mTimerNotifyFunction) {
 120     //
 121     // BUGBUG : This does not handle missed timer interrupts
 122     //
 123     mTimerNotifyFunction (mTimerPeriod);
 124   }
 125
 126   gBS->RestoreTPL (OriginalTPL);
 127 }
 128
 129 EFI_STATUS
 130 EFIAPI
 131 TimerDriverRegisterHandler (
 132   IN EFI_TIMER_ARCH_PROTOCOL  *This,
 133   IN EFI_TIMER_NOTIFY         NotifyFunction
 134   )
 135 /*++
 136
 137 Routine Description:
 138
 139   This function registers the handler NotifyFunction so it is called every time
 140   the timer interrupt fires.  It also passes the amount of time since the last
 141   handler call to the NotifyFunction.  If NotifyFunction is NULL, then the
 142   handler is unregistered.  If the handler is registered, then EFI_SUCCESS is
 143   returned.  If the CPU does not support registering a timer interrupt handler,
 144   then EFI_UNSUPPORTED is returned.  If an attempt is made to register a handler
 145   when a handler is already registered, then EFI_ALREADY_STARTED is returned.
 146   If an attempt is made to unregister a handler when a handler is not registered,
 147   then EFI_INVALID_PARAMETER is returned.  If an error occurs attempting to
 148   register the NotifyFunction with the timer interrupt, then EFI_DEVICE_ERROR
 149   is returned.
 150
 151 Arguments:
 152
 153   This           - The EFI_TIMER_ARCH_PROTOCOL instance.
 154
 155   NotifyFunction - The function to call when a timer interrupt fires.  This
 156                    function executes at TPL_HIGH_LEVEL.  The DXE Core will
 157                    register a handler for the timer interrupt, so it can know
 158                    how much time has passed.  This information is used to
 159                    signal timer based events.  NULL will unregister the handler.
 160
 161 Returns:
 162
 163   EFI_SUCCESS           - The timer handler was registered.
 164
 165   EFI_UNSUPPORTED       - The platform does not support timer interrupts.
 166
 167   EFI_ALREADY_STARTED   - NotifyFunction is not NULL, and a handler is already
 168                           registered.
 169
 170   EFI_INVALID_PARAMETER - NotifyFunction is NULL, and a handler was not
 171                           previously registered.
 172
 173   EFI_DEVICE_ERROR      - The timer handler could not be registered.
 174
 175 --*/
 176 {
 177   //
 178   // Check for invalid parameters
 179   //
 180   if (NotifyFunction == NULL && mTimerNotifyFunction == NULL) {
 181     return EFI_INVALID_PARAMETER;
 182   }
 183
 184   if (NotifyFunction != NULL && mTimerNotifyFunction != NULL) {
 185     return EFI_ALREADY_STARTED;
 186   }
 187
 188   mTimerNotifyFunction = NotifyFunction;
 189
 190   return EFI_SUCCESS;
 191 }
 192
 193 EFI_STATUS
 194 EFIAPI
 195 TimerDriverSetTimerPeriod (
 196   IN EFI_TIMER_ARCH_PROTOCOL  *This,
 197   IN UINT64                   TimerPeriod
 198   )
 199 /*++
 200
 201 Routine Description:
 202
 203   This function adjusts the period of timer interrupts to the value specified
 204   by TimerPeriod.  If the timer period is updated, then the selected timer
 205   period is stored in EFI_TIMER.TimerPeriod, and EFI_SUCCESS is returned.  If
 206   the timer hardware is not programmable, then EFI_UNSUPPORTED is returned.
 207   If an error occurs while attempting to update the timer period, then the
 208   timer hardware will be put back in its state prior to this call, and
 209   EFI_DEVICE_ERROR is returned.  If TimerPeriod is 0, then the timer interrupt
 210   is disabled.  This is not the same as disabling the CPU's interrupts.
 211   Instead, it must either turn off the timer hardware, or it must adjust the
 212   interrupt controller so that a CPU interrupt is not generated when the timer
 213   interrupt fires.
 214
 215 Arguments:
 216
 217   This        - The EFI_TIMER_ARCH_PROTOCOL instance.
 218
 219   TimerPeriod - The rate to program the timer interrupt in 100 nS units.  If
 220                 the timer hardware is not programmable, then EFI_UNSUPPORTED is
 221                 returned.  If the timer is programmable, then the timer period
 222                 will be rounded up to the nearest timer period that is supported
 223                 by the timer hardware.  If TimerPeriod is set to 0, then the
 224                 timer interrupts will be disabled.
 225
 226 Returns:
 227
 228   EFI_SUCCESS      - The timer period was changed.
 229
 230   EFI_UNSUPPORTED  - The platform cannot change the period of the timer interrupt.
 231
 232   EFI_DEVICE_ERROR - The timer period could not be changed due to a device error.
 233
 234 --*/
 235 {
 236   UINT64  TimerCount;
 237
 238   //
 239   //  The basic clock is 1.19318 MHz or 0.119318 ticks per 100 ns.
 240   //  TimerPeriod * 0.119318 = 8254 timer divisor. Using integer arithmetic
 241   //  TimerCount = (TimerPeriod * 119318)/1000000.
 242   //
 243   //  Round up to next highest integer. This guarantees that the timer is
 244   //  equal to or slightly longer than the requested time.
 245   //  TimerCount = ((TimerPeriod * 119318) + 500000)/1000000
 246   //
 247   // Note that a TimerCount of 0 is equivalent to a count of 65,536
 248   //
 249   // Since TimerCount is limited to 16 bits for IA32, TimerPeriod is limited
 250   // to 20 bits.
 251   //
 252   if (TimerPeriod == 0) {
 253     //
 254     // Disable timer interrupt for a TimerPeriod of 0
 255     //
 256     mLegacy8259->DisableIrq (mLegacy8259, Efi8259Irq0);
 257   } else {
 258
 259     //
 260     // Convert TimerPeriod into 8254 counts
 261     //
 262     TimerCount = DivU64x32 (MultU64x32 (119318, (UINT32) TimerPeriod) + 500000, 1000000);
 263
 264     //
 265     // Check for overflow
 266     //
 267     if (TimerCount >= 65536) {
 268       TimerCount = 0;
 269       if (TimerPeriod >= DEFAULT_TIMER_TICK_DURATION) {
 270         TimerPeriod = DEFAULT_TIMER_TICK_DURATION;
 271       }
 272     }
 273     //
 274     // Program the 8254 timer with the new count value
 275     //
 276     SetPitCount ((UINT16) TimerCount);
 277
 278     //
 279     // Enable timer interrupt
 280     //
 281     mLegacy8259->EnableIrq (mLegacy8259, Efi8259Irq0, FALSE);
 282   }
 283   //
 284   // Save the new timer period
 285   //
 286   mTimerPeriod = TimerPeriod;
 287
 288   return EFI_SUCCESS;
 289 }
 290
 291 EFI_STATUS
 292 EFIAPI
 293 TimerDriverGetTimerPeriod (
 294   IN EFI_TIMER_ARCH_PROTOCOL   *This,
 295   OUT UINT64                   *TimerPeriod
 296   )
 297 /*++
 298
 299 Routine Description:
 300
 301   This function retrieves the period of timer interrupts in 100 ns units,
 302   returns that value in TimerPeriod, and returns EFI_SUCCESS.  If TimerPeriod
 303   is NULL, then EFI_INVALID_PARAMETER is returned.  If a TimerPeriod of 0 is
 304   returned, then the timer is currently disabled.
 305
 306 Arguments:
 307
 308   This        - The EFI_TIMER_ARCH_PROTOCOL instance.
 309
 310   TimerPeriod - A pointer to the timer period to retrieve in 100 ns units.  If
 311                 0 is returned, then the timer is currently disabled.
 312
 313 Returns:
 314
 315   EFI_SUCCESS           - The timer period was returned in TimerPeriod.
 316
 317   EFI_INVALID_PARAMETER - TimerPeriod is NULL.
 318
 319 --*/
 320 {
 321   if (TimerPeriod == NULL) {
 322     return EFI_INVALID_PARAMETER;
 323   }
 324
 325   *TimerPeriod = mTimerPeriod;
 326
 327   return EFI_SUCCESS;
 328 }
 329
 330 EFI_STATUS
 331 EFIAPI
 332 TimerDriverGenerateSoftInterrupt (
 333   IN EFI_TIMER_ARCH_PROTOCOL  *This
 334   )
 335 /*++
 336
 337 Routine Description:
 338
 339   This function generates a soft timer interrupt. If the platform does not support soft
 340   timer interrupts, then EFI_UNSUPPORTED is returned. Otherwise, EFI_SUCCESS is returned.
 341   If a handler has been registered through the EFI_TIMER_ARCH_PROTOCOL.RegisterHandler()
 342   service, then a soft timer interrupt will be generated. If the timer interrupt is
 343   enabled when this service is called, then the registered handler will be invoked. The
 344   registered handler should not be able to distinguish a hardware-generated timer
 345   interrupt from a software-generated timer interrupt.
 346
 347 Arguments:
 348
 349   This  -  The EFI_TIMER_ARCH_PROTOCOL instance.
 350
 351 Returns:
 352
 353   EFI_SUCCESS       - The soft timer interrupt was generated.
 354
 355   EFI_UNSUPPORTEDT  - The platform does not support the generation of soft timer interrupts.
 356
 357 --*/
 358 {
 359   EFI_STATUS  Status;
 360   UINT16      IRQMask;
 361   EFI_TPL     OriginalTPL;
 362
 363   //
 364   // If the timer interrupt is enabled, then the registered handler will be invoked.
 365   //
 366   Status = mLegacy8259->GetMask (mLegacy8259, NULL, NULL, &IRQMask, NULL);
 367   ASSERT_EFI_ERROR (Status);
 368   if ((IRQMask & 0x1) == 0) {
 369     //
 370     // Invoke the registered handler
 371     //
 372     OriginalTPL = gBS->RaiseTPL (TPL_HIGH_LEVEL);
 373
 374     if (mTimerNotifyFunction) {
 375       //
 376       // BUGBUG : This does not handle missed timer interrupts
 377       //
 378       mTimerNotifyFunction (mTimerPeriod);
 379     }
 380
 381     gBS->RestoreTPL (OriginalTPL);
 382   } else {
 383     return EFI_UNSUPPORTED;
 384   }
 385
 386   return EFI_SUCCESS;
 387 }
 388
 389 EFI_STATUS
 390 EFIAPI
 391 TimerDriverInitialize (
 392   IN EFI_HANDLE        ImageHandle,
 393   IN EFI_SYSTEM_TABLE  *SystemTable
 394   )
 395 /*++
 396
 397 Routine Description:
 398
 399   Initialize the Timer Architectural Protocol driver
 400
 401 Arguments:
 402
 403   ImageHandle - ImageHandle of the loaded driver
 404
 405   SystemTable - Pointer to the System Table
 406
 407 Returns:
 408
 409   EFI_SUCCESS           - Timer Architectural Protocol created
 410
 411   EFI_OUT_OF_RESOURCES  - Not enough resources available to initialize driver.
 412
 413   EFI_DEVICE_ERROR      - A device error occured attempting to initialize the driver.
 414
 415 --*/
 416 {
 417   EFI_STATUS  Status;
 418   UINT32      TimerVector;
 419
 420   //
 421   // Initialize the pointer to our notify function.
 422   //
 423   mTimerNotifyFunction = NULL;
 424
 425   //
 426   // Make sure the Timer Architectural Protocol is not already installed in the system
 427   //
 428   ASSERT_PROTOCOL_ALREADY_INSTALLED (NULL, &gEfiTimerArchProtocolGuid);
 429
 430   //
 431   // Find the CPU architectural protocol.
 432   //
 433   Status = gBS->LocateProtocol (&gEfiCpuArchProtocolGuid, NULL, (VOID **) &mCpu);
 434   ASSERT_EFI_ERROR (Status);
 435
 436   //
 437   // Find the Legacy8259 protocol.
 438   //
 439   Status = gBS->LocateProtocol (&gEfiLegacy8259ProtocolGuid, NULL, (VOID **) &mLegacy8259);
 440   ASSERT_EFI_ERROR (Status);
 441
 442   //
 443   // Force the timer to be disabled
 444   //
 445   Status = TimerDriverSetTimerPeriod (&mTimer, 0);
 446   ASSERT_EFI_ERROR (Status);
 447
 448   //
 449   // Get the interrupt vector number corresponding to IRQ0 from the 8259 driver
 450   //
 451   TimerVector = 0;
 452   Status      = mLegacy8259->GetVector (mLegacy8259, Efi8259Irq0, (UINT8 *) &TimerVector);
 453   ASSERT_EFI_ERROR (Status);
 454
 455   //
 456   // Install interrupt handler for 8254 Timer #0 (ISA IRQ0)
 457   //
 458   Status = mCpu->RegisterInterruptHandler (mCpu, TimerVector, TimerInterruptHandler);
 459   ASSERT_EFI_ERROR (Status);
 460
 461   //
 462   // Force the timer to be enabled at its default period
 463   //
 464   Status = TimerDriverSetTimerPeriod (&mTimer, DEFAULT_TIMER_TICK_DURATION);
 465   ASSERT_EFI_ERROR (Status);
 466
 467   //
 468   // Install the Timer Architectural Protocol onto a new handle
 469   //
 470   Status = gBS->InstallMultipleProtocolInterfaces (
 471                   &mTimerHandle,
 472                   &gEfiTimerArchProtocolGuid, &mTimer,
 473                   NULL
 474                   );
 475   ASSERT_EFI_ERROR (Status);
 476
 477   return Status;
 478 }
 479