MdePkg/Library/BaseTimerLibLocalApic/x86TimerLib.c

   1 /** @file
   2   Timer Library functions built upon local APIC on IA32/x64.
   3
   4   @bug Should use PCD to retrieve all the constants including index of
   5   the IA32_APIC_BASE MSR, the offsets of InitialCount, CorrentCount
   6   and DivideConfiguration.
   7
   8   Copyright (c) 2006, Intel Corporation<BR>
   9   All rights reserved. This program and the accompanying materials
  10   are licensed and made available under the terms and conditions of the BSD License
  11   which accompanies this distribution.  The full text of the license may be found at
  12   http://opensource.org/licenses/bsd-license.php
  13
  14   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  15   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  16
  17   Module Name:  x86TimerLib.c
  18
  19 **/
  20
  21 static
  22 UINTN
  23 EFIAPI
  24 DelayWorker (
  25   IN      UINT64                    NDelay
  26   )
  27 {
  28   UINT64                            Ticks;
  29
  30   Ticks = GetPerformanceCounter ();
  31   Ticks -= DivU64x32 (
  32              MultU64x64 (
  33                GetPerformanceCounterProperties (NULL, NULL),
  34                NDelay
  35                ),
  36              1000000000u
  37              );
  38   while (Ticks <= GetPerformanceCounter ());
  39   return (UINTN)Ticks;
  40 }
  41
  42 /**
  43   Stalls the CPU for at least the given number of microseconds.
  44
  45   Stalls the CPU for the number of microseconds specified by MicroSeconds.
  46
  47   @param  MicroSeconds  The minimum number of microseconds to delay.
  48
  49   @return Return value depends on implementation.
  50
  51 **/
  52 UINTN
  53 EFIAPI
  54 MicroSecondDelay (
  55   IN      UINTN                     MicroSeconds
  56   )
  57 {
  58   return DelayWorker (MicroSeconds * 1000ull);
  59 }
  60
  61 /**
  62   Stalls the CPU for at least the given number of nanoseconds.
  63
  64   Stalls the CPU for the number of nanoseconds specified by NanoSeconds.
  65
  66   @param  NanoSeconds The minimum number of nanoseconds to delay.
  67
  68   @return Return value depends on implementation.
  69
  70 **/
  71 UINTN
  72 EFIAPI
  73 NanoSecondDelay (
  74   IN      UINTN                     NanoSeconds
  75   )
  76 {
  77   return DelayWorker (NanoSeconds);
  78 }
  79
  80 static
  81 UINTN
  82 EFIAPI
  83 GetApicBase (
  84   VOID
  85   )
  86 {
  87   return (UINTN)AsmMsrBitFieldRead64 (27, 12, 35) << 12;
  88 }
  89
  90 /**
  91   Retrieves the current value of a 64-bit free running performance counter.
  92
  93   Retrieves the current value of a 64-bit free running performance counter. The
  94   counter can either count up by 1 or count down by 1. If the physical
  95   performance counter counts by a larger increment, then the counter values
  96   must be translated. The properties of the counter can be retrieved from
  97   GetPerformanceCounterProperties().
  98
  99   @return The current value of the free running performance counter.
 100
 101 **/
 102 UINT64
 103 EFIAPI
 104 GetPerformanceCounter (
 105   VOID
 106   )
 107 {
 108   return MmioRead32 (GetApicBase () + 0x390);
 109 }
 110
 111 /**
 112   Retrieves the 64-bit frequency in Hz and the range of performance counter
 113   values.
 114
 115   If StartValue is not NULL, then the value that the performance counter starts
 116   with immediately after is it rolls over is returned in StartValue. If
 117   EndValue is not NULL, then the value that the performance counter end with
 118   immediately before it rolls over is returned in EndValue. The 64-bit
 119   frequency of the performance counter in Hz is always returned. If StartValue
 120   is less than EndValue, then the performance counter counts up. If StartValue
 121   is greater than EndValue, then the performance counter counts down. For
 122   example, a 64-bit free running counter that counts up would have a StartValue
 123   of 0 and an EndValue of 0xFFFFFFFFFFFFFFFF. A 24-bit free running counter
 124   that counts down would have a StartValue of 0xFFFFFF and an EndValue of 0.
 125
 126   @param  StartValue  The value the performance counter starts with when it
 127                       rolls over.
 128   @param  EndValue    The value that the performance counter ends with before
 129                       it rolls over.
 130
 131   @return The frequency in Hz.
 132
 133 **/
 134 UINT64
 135 EFIAPI
 136 GetPerformanceCounterProperties (
 137   IN      UINT64                    *StartValue,
 138   IN      UINT64                    *EndValue
 139   )
 140 {
 141   static const UINT32               mFrequencies[] = {
 142     100000000,
 143     133000000,
 144     200000000,
 145     166000000
 146   };
 147   static const UINT8                mDivisor[] = {
 148     0x02, 0x04, 0x08, 0x10,
 149     0x02, 0x04, 0x08, 0x10,
 150     0x20, 0x40, 0x80, 0x01,
 151     0x20, 0x40, 0x80, 0x01
 152   };
 153
 154   UINTN                             ApicBase;
 155
 156   ApicBase = GetApicBase ();
 157
 158   if (StartValue != NULL) {
 159     *StartValue = MmioRead32 (ApicBase + 0x380);
 160   }
 161
 162   if (EndValue != NULL) {
 163     *EndValue = 0;
 164   }
 165
 166   return mFrequencies[AsmMsrBitFieldRead32 (44, 16, 18)] /
 167          mDivisor[MmioBitFieldRead32 (ApicBase + 0x3e0, 0, 3)];
 168 }