updated the comment according to latest version of MWG.

[mirror_edk2.git] / MdePkg / Library / SecPeiDxeTimerLibCpu / x86TimerLib.c

/** @file\r
  Timer Library functions built upon local APIC on IA32/x64.\r
\r
  Copyright (c) 2006 - 2007, Intel Corporation<BR>\r
  All rights reserved. This program and the accompanying materials\r
  are licensed and made available under the terms and conditions of the BSD License\r
  which accompanies this distribution.  The full text of the license may be found at\r
  http://opensource.org/licenses/bsd-license.php\r
\r
  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r
  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
\r
  Module Name:  x86TimerLib.c\r
\r
**/\r
\r
//\r
// The following array is used in calculating the frequency of local APIC\r
// timer. Refer to IA-32 developers' manual for more details.\r
//\r
GLOBAL_REMOVE_IF_UNREFERENCED\r
CONST UINT8                           mTimerLibLocalApicDivisor[] = {\r
  0x02, 0x04, 0x08, 0x10,\r
  0x02, 0x04, 0x08, 0x10,\r
  0x20, 0x40, 0x80, 0x01,\r
  0x20, 0x40, 0x80, 0x01\r
};\r
\r
/**\r
  Internal function to retrieve the base address of local APIC.\r
\r
  Internal function to retrieve the base address of local APIC.\r
\r
  @return The base address of local APIC\r
\r
**/\r
STATIC\r
UINTN\r
InternalX86GetApicBase (\r
  VOID\r
  )\r
{\r
  return (UINTN)AsmMsrBitFieldRead64 (27, 12, 35) << 12;\r
}\r
\r
/**\r
  Internal function to return the frequency of the local APIC timer.\r
\r
  Internal function to return the frequency of the local APIC timer.\r
\r
  @param  ApicBase  The base address of memory mapped registers of local APIC.\r
\r
  @return The frequency of the timer in Hz.\r
\r
**/\r
STATIC\r
UINT32\r
InternalX86GetTimerFrequency (\r
  IN      UINTN                     ApicBase\r
  )\r
{\r
  return\r
    PcdGet32(PcdFSBClock) /\r
    mTimerLibLocalApicDivisor[MmioBitFieldRead32 (ApicBase + 0x3e0, 0, 3)];\r
}\r
\r
/**\r
  Internal function to read the current tick counter of local APIC.\r
\r
  Internal function to read the current tick counter of local APIC.\r
\r
  @param  ApicBase  The base address of memory mapped registers of local APIC.\r
\r
  @return The tick counter read.\r
\r
**/\r
STATIC\r
INT32\r
InternalX86GetTimerTick (\r
  IN      UINTN                     ApicBase\r
  )\r
{\r
  return MmioRead32 (ApicBase + 0x390);\r
}\r
\r
/**\r
  Stalls the CPU for at least the given number of ticks.\r
\r
  Stalls the CPU for at least the given number of ticks. It's invoked by\r
  MicroSecondDelay() and NanoSecondDelay().\r
\r
  @param  ApicBase  The base address of memory mapped registers of local APIC.\r
  @param  Delay     A period of time to delay in ticks.\r
\r
**/\r
STATIC\r
VOID\r
InternalX86Delay (\r
  IN      UINTN                     ApicBase,\r
  IN      UINT32                    Delay\r
  )\r
{\r
  INT32                             Ticks;\r
\r
  //\r
  // The target timer count is calculated here\r
  //\r
  Ticks = InternalX86GetTimerTick (ApicBase) - Delay;\r
\r
  //\r
  // Wait until time out\r
  // Delay > 2^31 could not be handled by this function\r
  // Timer wrap-arounds are handled correctly by this function\r
  //\r
  while (InternalX86GetTimerTick (ApicBase) - Ticks >= 0);\r
}\r
\r
/**\r
  Stalls the CPU for at least the given number of microseconds.\r
\r
  Stalls the CPU for the number of microseconds specified by MicroSeconds.\r
\r
  @param  MicroSeconds  The minimum number of microseconds to delay.\r
\r
  @return MicroSeconds\r
\r
**/\r
UINTN\r
EFIAPI\r
MicroSecondDelay (\r
  IN      UINTN                     MicroSeconds\r
  )\r
{\r
  UINTN                             ApicBase;\r
\r
  ApicBase = InternalX86GetApicBase ();\r
  InternalX86Delay (\r
    ApicBase,\r
    (UINT32)DivU64x32 (\r
              MultU64x64 (\r
                InternalX86GetTimerFrequency (ApicBase),\r
                MicroSeconds\r
                ),\r
              1000000u\r
              )\r
    );\r
  return MicroSeconds;\r
}\r
\r
/**\r
  Stalls the CPU for at least the given number of nanoseconds.\r
\r
  Stalls the CPU for the number of nanoseconds specified by NanoSeconds.\r
\r
  @param  NanoSeconds The minimum number of nanoseconds to delay.\r
\r
  @return NanoSeconds\r
\r
**/\r
UINTN\r
EFIAPI\r
NanoSecondDelay (\r
  IN      UINTN                     NanoSeconds\r
  )\r
{\r
  UINTN                             ApicBase;\r
\r
  ApicBase = InternalX86GetApicBase ();\r
  InternalX86Delay (\r
    ApicBase,\r
    (UINT32)DivU64x32 (\r
              MultU64x64 (\r
                InternalX86GetTimerFrequency (ApicBase),\r
                NanoSeconds\r
                ),\r
              1000000000u\r
              )\r
    );\r
  return NanoSeconds;\r
}\r
\r
/**\r
  Retrieves the current value of a 64-bit free running performance counter.\r
\r
  Retrieves the current value of a 64-bit free running performance counter. The\r
  counter can either count up by 1 or count down by 1. If the physical\r
  performance counter counts by a larger increment, then the counter values\r
  must be translated. The properties of the counter can be retrieved from\r
  GetPerformanceCounterProperties().\r
\r
  @return The current value of the free running performance counter.\r
\r
**/\r
UINT64\r
EFIAPI\r
GetPerformanceCounter (\r
  VOID\r
  )\r
{\r
  return (UINT64)(UINT32)InternalX86GetTimerTick (InternalX86GetApicBase ());\r
}\r
\r
/**\r
  Retrieves the 64-bit frequency in Hz and the range of performance counter\r
  values.\r
\r
  If StartValue is not NULL, then the value that the performance counter starts\r
  with immediately after is it rolls over is returned in StartValue. If\r
  EndValue is not NULL, then the value that the performance counter end with\r
  immediately before it rolls over is returned in EndValue. The 64-bit\r
  frequency of the performance counter in Hz is always returned. If StartValue\r
  is less than EndValue, then the performance counter counts up. If StartValue\r
  is greater than EndValue, then the performance counter counts down. For\r
  example, a 64-bit free running counter that counts up would have a StartValue\r
  of 0 and an EndValue of 0xFFFFFFFFFFFFFFFF. A 24-bit free running counter\r
  that counts down would have a StartValue of 0xFFFFFF and an EndValue of 0.\r
\r
  @param  StartValue  The value the performance counter starts with when it\r
                      rolls over.\r
  @param  EndValue    The value that the performance counter ends with before\r
                      it rolls over.\r
\r
  @return The frequency in Hz.\r
\r
**/\r
UINT64\r
EFIAPI\r
GetPerformanceCounterProperties (\r
  OUT      UINT64                    *StartValue,  OPTIONAL\r
  OUT      UINT64                    *EndValue     OPTIONAL\r
  )\r
{\r
  UINTN                             ApicBase;\r
\r
  ApicBase = InternalX86GetApicBase ();\r
\r
  if (StartValue != NULL) {\r
    *StartValue = MmioRead32 (ApicBase + 0x380);\r
  }\r
\r
  if (EndValue != NULL) {\r
    *EndValue = 0;\r
  }\r
\r
  return (UINT64) InternalX86GetTimerFrequency (ApicBase);;\r
}\r