UefiCpuPkg/Library/SecPeiDxeTimerLibUefiCpu/X86TimerLib.c

   1 /** @file
   2   Timer Library functions built upon local APIC on IA32/x64.
   3
   4   This library uses the local APIC library so that it supports x2APIC mode.
   5
   6   Copyright (c) 2010 - 2018, Intel Corporation. All rights reserved.<BR>
   7   This program and the accompanying materials
   8   are licensed and made available under the terms and conditions of the BSD License
   9   which accompanies this distribution.  The full text of the license may be found at
  10   http://opensource.org/licenses/bsd-license.php.
  11
  12   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  13   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  14
  15 **/
  16
  17 #include <Base.h>
  18 #include <Library/TimerLib.h>
  19 #include <Library/BaseLib.h>
  20 #include <Library/PcdLib.h>
  21 #include <Library/DebugLib.h>
  22 #include <Library/LocalApicLib.h>
  23
  24 /**
  25   Internal function to return the frequency of the local APIC timer.
  26
  27   @return The frequency of the timer in Hz.
  28
  29 **/
  30 UINT32
  31 EFIAPI
  32 InternalX86GetTimerFrequency (
  33   VOID
  34   )
  35 {
  36   UINTN Divisor;
  37
  38   GetApicTimerState (&Divisor, NULL, NULL);
  39   return PcdGet32(PcdFSBClock) / (UINT32)Divisor;
  40 }
  41
  42 /**
  43   Stalls the CPU for at least the given number of ticks.
  44
  45   Stalls the CPU for at least the given number of ticks. It's invoked by
  46   MicroSecondDelay() and NanoSecondDelay().
  47
  48   This function will ASSERT if the APIC timer intial count returned from
  49   GetApicTimerInitCount() is zero.
  50
  51   @param  Delay     A period of time to delay in ticks.
  52
  53 **/
  54 VOID
  55 EFIAPI
  56 InternalX86Delay (
  57   IN      UINT32                    Delay
  58   )
  59 {
  60   INT32                             Ticks;
  61   UINT32                            Times;
  62   UINT32                            InitCount;
  63   UINT32                            StartTick;
  64
  65   //
  66   // In case Delay is too larger, separate it into several small delay slot.
  67   // Devided Delay by half value of Init Count is to avoid Delay close to
  68   // the Init Count, timeout maybe missing if the time consuming between 2
  69   // GetApicTimerCurrentCount() invoking is larger than the time gap between
  70   // Delay and the Init Count.
  71   //
  72   InitCount = GetApicTimerInitCount ();
  73   ASSERT (InitCount != 0);
  74   Times     = Delay / (InitCount / 2);
  75   Delay     = Delay % (InitCount / 2);
  76
  77   //
  78   // Get Start Tick and do delay
  79   //
  80   StartTick  = GetApicTimerCurrentCount ();
  81   do {
  82     //
  83     // Wait until time out by Delay value
  84     //
  85     do {
  86       CpuPause ();
  87       //
  88       // Get Ticks from Start to Current.
  89       //
  90       Ticks = StartTick - GetApicTimerCurrentCount ();
  91       //
  92       // Ticks < 0 means Timer wrap-arounds happens.
  93       //
  94       if (Ticks < 0) {
  95         Ticks += InitCount;
  96       }
  97     } while ((UINT32)Ticks < Delay);
  98
  99     //
 100     // Update StartTick and Delay for next delay slot
 101     //
 102     StartTick -= (StartTick > Delay) ?  Delay : (Delay - InitCount);
 103     Delay      = InitCount / 2;
 104   } while (Times-- > 0);
 105 }
 106
 107 /**
 108   Stalls the CPU for at least the given number of microseconds.
 109
 110   Stalls the CPU for the number of microseconds specified by MicroSeconds.
 111
 112   @param  MicroSeconds  The minimum number of microseconds to delay.
 113
 114   @return The value of MicroSeconds inputted.
 115
 116 **/
 117 UINTN
 118 EFIAPI
 119 MicroSecondDelay (
 120   IN      UINTN                     MicroSeconds
 121   )
 122 {
 123   InternalX86Delay (
 124     (UINT32)DivU64x32 (
 125               MultU64x64 (
 126                 InternalX86GetTimerFrequency (),
 127                 MicroSeconds
 128                 ),
 129               1000000u
 130               )
 131     );
 132   return MicroSeconds;
 133 }
 134
 135 /**
 136   Stalls the CPU for at least the given number of nanoseconds.
 137
 138   Stalls the CPU for the number of nanoseconds specified by NanoSeconds.
 139
 140   @param  NanoSeconds The minimum number of nanoseconds to delay.
 141
 142   @return The value of NanoSeconds inputted.
 143
 144 **/
 145 UINTN
 146 EFIAPI
 147 NanoSecondDelay (
 148   IN      UINTN                     NanoSeconds
 149   )
 150 {
 151   InternalX86Delay (
 152     (UINT32)DivU64x32 (
 153               MultU64x64 (
 154                 InternalX86GetTimerFrequency (),
 155                 NanoSeconds
 156                 ),
 157               1000000000u
 158               )
 159     );
 160   return NanoSeconds;
 161 }
 162
 163 /**
 164   Retrieves the current value of a 64-bit free running performance counter.
 165
 166   The counter can either count up by 1 or count down by 1. If the physical
 167   performance counter counts by a larger increment, then the counter values
 168   must be translated. The properties of the counter can be retrieved from
 169   GetPerformanceCounterProperties().
 170
 171   @return The current value of the free running performance counter.
 172
 173 **/
 174 UINT64
 175 EFIAPI
 176 GetPerformanceCounter (
 177   VOID
 178   )
 179 {
 180   return (UINT64)GetApicTimerCurrentCount ();
 181 }
 182
 183 /**
 184   Retrieves the 64-bit frequency in Hz and the range of performance counter
 185   values.
 186
 187   If StartValue is not NULL, then the value that the performance counter starts
 188   with immediately after is it rolls over is returned in StartValue. If
 189   EndValue is not NULL, then the value that the performance counter end with
 190   immediately before it rolls over is returned in EndValue. The 64-bit
 191   frequency of the performance counter in Hz is always returned. If StartValue
 192   is less than EndValue, then the performance counter counts up. If StartValue
 193   is greater than EndValue, then the performance counter counts down. For
 194   example, a 64-bit free running counter that counts up would have a StartValue
 195   of 0 and an EndValue of 0xFFFFFFFFFFFFFFFF. A 24-bit free running counter
 196   that counts down would have a StartValue of 0xFFFFFF and an EndValue of 0.
 197
 198   @param  StartValue  The value the performance counter starts with when it
 199                       rolls over.
 200   @param  EndValue    The value that the performance counter ends with before
 201                       it rolls over.
 202
 203   @return The frequency in Hz.
 204
 205 **/
 206 UINT64
 207 EFIAPI
 208 GetPerformanceCounterProperties (
 209   OUT      UINT64                    *StartValue,  OPTIONAL
 210   OUT      UINT64                    *EndValue     OPTIONAL
 211   )
 212 {
 213   if (StartValue != NULL) {
 214     *StartValue = (UINT64)GetApicTimerInitCount ();
 215   }
 216
 217   if (EndValue != NULL) {
 218     *EndValue = 0;
 219   }
 220
 221   return (UINT64) InternalX86GetTimerFrequency ();
 222 }
 223
 224 /**
 225   Converts elapsed ticks of performance counter to time in nanoseconds.
 226
 227   This function converts the elapsed ticks of running performance counter to
 228   time value in unit of nanoseconds.
 229
 230   @param  Ticks     The number of elapsed ticks of running performance counter.
 231
 232   @return The elapsed time in nanoseconds.
 233
 234 **/
 235 UINT64
 236 EFIAPI
 237 GetTimeInNanoSecond (
 238   IN      UINT64                     Ticks
 239   )
 240 {
 241   UINT64  Frequency;
 242   UINT64  NanoSeconds;
 243   UINT64  Remainder;
 244   INTN    Shift;
 245
 246   Frequency = GetPerformanceCounterProperties (NULL, NULL);
 247
 248   //
 249   //          Ticks
 250   // Time = --------- x 1,000,000,000
 251   //        Frequency
 252   //
 253   NanoSeconds = MultU64x32 (DivU64x64Remainder (Ticks, Frequency, &Remainder), 1000000000u);
 254
 255   //
 256   // Ensure (Remainder * 1,000,000,000) will not overflow 64-bit.
 257   // Since 2^29 < 1,000,000,000 = 0x3B9ACA00 < 2^30, Remainder should < 2^(64-30) = 2^34,
 258   // i.e. highest bit set in Remainder should <= 33.
 259   //
 260   Shift = MAX (0, HighBitSet64 (Remainder) - 33);
 261   Remainder = RShiftU64 (Remainder, (UINTN) Shift);
 262   Frequency = RShiftU64 (Frequency, (UINTN) Shift);
 263   NanoSeconds += DivU64x64Remainder (MultU64x32 (Remainder, 1000000000u), Frequency, NULL);
 264
 265   return NanoSeconds;
 266 }