ArmPkg/Library/ArmArchTimerLib/ArmArchTimerLib.c

   1 /** @file
   2   Generic ARM implementation of TimerLib.h
   3
   4   Copyright (c) 2011-2014, ARM Limited. All rights reserved.
   5
   6   This program and the accompanying materials
   7   are licensed and made available under the terms and conditions of the BSD License
   8   which accompanies this distribution.  The full text of the license may be found at
   9   http://opensource.org/licenses/bsd-license.php
  10
  11   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  12   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  13
  14 **/
  15
  16
  17 #include <Base.h>
  18 #include <Library/ArmLib.h>
  19 #include <Library/BaseLib.h>
  20 #include <Library/TimerLib.h>
  21 #include <Library/DebugLib.h>
  22 #include <Library/PcdLib.h>
  23 #include <Library/ArmGenericTimerCounterLib.h>
  24
  25 #define TICKS_PER_MICRO_SEC     (PcdGet32 (PcdArmArchTimerFreqInHz)/1000000U)
  26
  27 RETURN_STATUS
  28 EFIAPI
  29 TimerConstructor (
  30   VOID
  31   )
  32 {
  33   // Check if the ARM Generic Timer Extension is implemented
  34   if (ArmIsArchTimerImplemented ()) {
  35
  36     UINTN TimerFreq;
  37
  38     // Check if Architectural Timer frequency is valid number (should not be 0)
  39     ASSERT (PcdGet32 (PcdArmArchTimerFreqInHz));
  40
  41     // Check if ticks/uS is not 0. The Architectural timer runs at constant
  42     // frequency irrespective of CPU frequency. According to General Timer Ref
  43     // manual lower bound of the frequency is in the range of 1-10MHz
  44     ASSERT (TICKS_PER_MICRO_SEC);
  45
  46 #ifdef MDE_CPU_ARM
  47     // Only set the frequency for ARMv7. We expect the secure firmware to have already do it
  48     // If the security extensions are not implemented set Timer Frequency
  49     if ((ArmReadIdPfr1 () & ARM_PFR1_SEC) == 0x0) {
  50       ArmGenericTimerSetTimerFreq (PcdGet32 (PcdArmArchTimerFreqInHz));
  51     }
  52 #endif
  53
  54     // Architectural Timer Frequency must be set in the Secure privileged(if secure extensions are supported) mode.
  55     // If the reset value (0) is returned just ASSERT.
  56     TimerFreq = ArmGenericTimerGetTimerFreq ();
  57     ASSERT (TimerFreq != 0);
  58
  59   } else {
  60     DEBUG ((EFI_D_ERROR, "ARM Architectural Timer is not available in the CPU, hence this library can not be used.\n"));
  61     ASSERT (0);
  62   }
  63
  64   return RETURN_SUCCESS;
  65 }
  66
  67
  68 /**
  69   Stalls the CPU for the number of microseconds specified by MicroSeconds.
  70
  71   @param  MicroSeconds  The minimum number of microseconds to delay.
  72
  73   @return The value of MicroSeconds inputted.
  74
  75 **/
  76 UINTN
  77 EFIAPI
  78 MicroSecondDelay (
  79   IN      UINTN                     MicroSeconds
  80   )
  81 {
  82   UINT64 TimerTicks64;
  83   UINT64 SystemCounterVal;
  84
  85   // Calculate counter ticks that can represent requested delay:
  86   //  = MicroSeconds x TICKS_PER_MICRO_SEC
  87   //  = MicroSeconds x Frequency.10^-6
  88   TimerTicks64 = (MicroSeconds * PcdGet32 (PcdArmArchTimerFreqInHz)) / 1000000U;
  89
  90   // Read System Counter value
  91   SystemCounterVal = ArmGenericTimerGetSystemCount ();
  92
  93   TimerTicks64 += SystemCounterVal;
  94
  95   // Wait until delay count is expired.
  96   while (SystemCounterVal < TimerTicks64) {
  97     SystemCounterVal = ArmGenericTimerGetSystemCount ();
  98   }
  99
 100   return MicroSeconds;
 101 }
 102
 103
 104 /**
 105   Stalls the CPU for at least the given number of nanoseconds.
 106
 107   Stalls the CPU for the number of nanoseconds specified by NanoSeconds.
 108
 109   When the timer frequency is 1MHz, each tick corresponds to 1 microsecond.
 110   Therefore, the nanosecond delay will be rounded up to the nearest 1 microsecond.
 111
 112   @param  NanoSeconds The minimum number of nanoseconds to delay.
 113
 114   @return The value of NanoSeconds inputed.
 115
 116 **/
 117 UINTN
 118 EFIAPI
 119 NanoSecondDelay (
 120   IN  UINTN NanoSeconds
 121   )
 122 {
 123   UINTN  MicroSeconds;
 124
 125   // Round up to 1us Tick Number
 126   MicroSeconds = NanoSeconds / 1000;
 127   MicroSeconds += ((NanoSeconds % 1000) == 0) ? 0 : 1;
 128
 129   MicroSecondDelay (MicroSeconds);
 130
 131   return NanoSeconds;
 132 }
 133
 134 /**
 135   Retrieves the current value of a 64-bit free running performance counter.
 136
 137   The counter can either count up by 1 or count down by 1. If the physical
 138   performance counter counts by a larger increment, then the counter values
 139   must be translated. The properties of the counter can be retrieved from
 140   GetPerformanceCounterProperties().
 141
 142   @return The current value of the free running performance counter.
 143
 144 **/
 145 UINT64
 146 EFIAPI
 147 GetPerformanceCounter (
 148   VOID
 149   )
 150 {
 151   // Just return the value of system count
 152   return ArmGenericTimerGetSystemCount ();
 153 }
 154
 155 /**
 156   Retrieves the 64-bit frequency in Hz and the range of performance counter
 157   values.
 158
 159   If StartValue is not NULL, then the value that the performance counter starts
 160   with immediately after is it rolls over is returned in StartValue. If
 161   EndValue is not NULL, then the value that the performance counter end with
 162   immediately before it rolls over is returned in EndValue. The 64-bit
 163   frequency of the performance counter in Hz is always returned. If StartValue
 164   is less than EndValue, then the performance counter counts up. If StartValue
 165   is greater than EndValue, then the performance counter counts down. For
 166   example, a 64-bit free running counter that counts up would have a StartValue
 167   of 0 and an EndValue of 0xFFFFFFFFFFFFFFFF. A 24-bit free running counter
 168   that counts down would have a StartValue of 0xFFFFFF and an EndValue of 0.
 169
 170   @param  StartValue  The value the performance counter starts with when it
 171                       rolls over.
 172   @param  EndValue    The value that the performance counter ends with before
 173                       it rolls over.
 174
 175   @return The frequency in Hz.
 176
 177 **/
 178 UINT64
 179 EFIAPI
 180 GetPerformanceCounterProperties (
 181   OUT      UINT64                    *StartValue,  OPTIONAL
 182   OUT      UINT64                    *EndValue     OPTIONAL
 183   )
 184 {
 185   if (StartValue != NULL) {
 186     // Timer starts with the reload value
 187     *StartValue = (UINT64)0ULL ;
 188   }
 189
 190   if (EndValue != NULL) {
 191     // Timer counts down to 0x0
 192     *EndValue = 0xFFFFFFFFFFFFFFFFUL;
 193   }
 194
 195   return (UINT64)ArmGenericTimerGetTimerFreq ();
 196 }