boot/environ/lib/platform/time.c

   1 /*
   2  * COPYRIGHT:       See COPYING.ARM in the top level directory
   3  * PROJECT:         ReactOS UEFI Boot Library
   4  * FILE:            boot/environ/lib/platform/time.c
   5  * PURPOSE:         Boot Library Time Management Routines
   6  * PROGRAMMER:      Alex Ionescu (alex.ionescu@reactos.org)
   7  */
   8
   9 /* INCLUDES ******************************************************************/
  10
  11 #include "bl.h"
  12
  13 /* DATA VARIABLES ************************************************************/
  14
  15 ULONGLONG BlpTimePerformanceFrequency;
  16
  17 /* FUNCTIONS *****************************************************************/
  18
  19 NTSTATUS
  20 BlpTimeMeasureTscFrequency (
  21     VOID
  22     )
  23 {
  24 #if defined(_M_IX86) || defined(_M_X64)
  25     ULONG Count;
  26     INT CpuInfo[4];
  27     ULONGLONG TimeStamp1, TimeStamp2, Delta;
  28
  29     /* Check if the ISVM bit it set, meaning we're in a hypervisor */
  30     __cpuid(CpuInfo, 1);
  31     Count = CpuInfo[2] & 0x80000000 ? 10 : 1;
  32
  33     /* Loop trying to get an accurate TSC */
  34     do
  35     {
  36         /* Stall for 1us and get count 1 */
  37         EfiStall(1);
  38         TimeStamp1 = __rdtsc();
  39
  40         /* Stall for 1000us and get count 2*/
  41         EfiStall(1000);
  42         TimeStamp2 = __rdtsc();
  43
  44         /* Stall for 9000us and get the difference */
  45         EfiStall(9000);
  46         Delta = __rdtsc() - TimeStamp2;
  47
  48         /* Keep going as long as the TSC is fluctuating */
  49         --Count;
  50     } while (((TimeStamp2 - TimeStamp1) > Delta) && (Count));
  51
  52     /* Set the frequency based on the two measurements we took */
  53     BlpTimePerformanceFrequency = 125 * (Delta - (TimeStamp2 - TimeStamp1)) & 0x1FFFFFFFFFFFFFF;
  54     return STATUS_SUCCESS;
  55 #else
  56     EfiPrintf(L"BlpTimeMeasureTscFrequency not implemented for this platform.\r\n");
  57     return STATUS_NOT_IMPLEMENTED;
  58 #endif
  59 }
  60
  61 NTSTATUS
  62 BlpTimeCalibratePerformanceCounter (
  63     VOID
  64     )
  65 {
  66 #if defined(_M_IX86) || defined(_M_X64)
  67     INT CpuInfo[4];
  68
  69     /* Check if the ISVM bit it set, meaning we're in a hypervisor */
  70     __cpuid(CpuInfo, 1);
  71     if (CpuInfo[2] & 0x80000000)
  72     {
  73         /* Get the Hypervisor Identification Leaf */
  74         __cpuid(CpuInfo, 0x40000001);
  75
  76         /* Is this Hyper-V? */
  77         if (CpuInfo[0] == '1#vH')
  78         {
  79             /* Get the Hypervisor Feature Identification Leaf */
  80             __cpuid(CpuInfo, 0x40000003);
  81
  82             /* Check if HV_X64_MSR_REFERENCE_TSC is present */
  83             if (CpuInfo[3] & 0x100)
  84             {
  85                 /* Read the TSC frequency from the MSR */
  86                 BlpTimePerformanceFrequency = __readmsr(0x40000022);
  87                 return STATUS_SUCCESS;
  88             }
  89         }
  90     }
  91
  92     /* On other systems, compute it */
  93     return BlpTimeMeasureTscFrequency();
  94 #else
  95     EfiPrintf(L"BlpTimeCalibratePerformanceCounter not implemented for this platform.\r\n");
  96     return STATUS_NOT_IMPLEMENTED;
  97 #endif
  98 }
  99
 100 ULONGLONG
 101 BlTimeQueryPerformanceCounter (
 102     _Out_opt_ PLARGE_INTEGER Frequency
 103     )
 104 {
 105 #if defined(_M_IX86) || defined(_M_X64)
 106     /* Check if caller wants frequency */
 107     if (Frequency)
 108     {
 109         /* Return it */
 110         Frequency->QuadPart = BlpTimePerformanceFrequency;
 111     }
 112
 113     /* Return the TSC value */
 114     return __rdtsc();
 115 #else
 116     EfiPrintf(L"BlTimeQueryPerformanceCounter not implemented for this platform.\r\n");
 117     return 0;
 118 #endif
 119 };