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   //
  34   // Check if the ARM Generic Timer Extension is implemented.
  35   //
  36   if (ArmIsArchTimerImplemented ()) {
  37     UINTN TimerFreq;
  38
  39     //
  40     // Check if Architectural Timer frequency is valid (should not be 0).
  41     //
  42     ASSERT (PcdGet32 (PcdArmArchTimerFreqInHz));
  43
  44     //
  45     // Check if ticks/uS is not 0. The Architectural timer runs at constant
  46     // frequency, irrespective of CPU frequency. According to General Timer
  47     // Ref manual, lower bound of the frequency is in the range of 1-10MHz.
  48     //
  49     ASSERT (TICKS_PER_MICRO_SEC);
  50
  51 #ifdef MDE_CPU_ARM
  52     //
  53     // Only set the frequency for ARMv7. We expect the secure firmware to
  54     // have already done it.
  55     // If the security extension is not implemented, set Timer Frequency
  56     // here.
  57     //
  58     if ((ArmReadIdPfr1 () & ARM_PFR1_SEC) == 0x0) {
  59       ArmGenericTimerSetTimerFreq (PcdGet32 (PcdArmArchTimerFreqInHz));
  60     }
  61 #endif
  62
  63     //
  64     // Architectural Timer Frequency must be set in the Secure privileged
  65     // mode (if secure extension is supported).
  66     // If the reset value (0) is returned, just ASSERT.
  67     //
  68     TimerFreq = ArmGenericTimerGetTimerFreq ();
  69     ASSERT (TimerFreq != 0);
  70   } else {
  71     DEBUG ((EFI_D_ERROR, "ARM Architectural Timer is not available in the CPU, hence this library can not be used.\n"));
  72     ASSERT (0);
  73   }
  74
  75   return RETURN_SUCCESS;
  76 }
  77
  78
  79 /**
  80   Stalls the CPU for the number of microseconds specified by MicroSeconds.
  81
  82   @param  MicroSeconds  The minimum number of microseconds to delay.
  83
  84   @return The value of MicroSeconds inputted.
  85
  86 **/
  87 UINTN
  88 EFIAPI
  89 MicroSecondDelay (
  90   IN      UINTN                     MicroSeconds
  91   )
  92 {
  93   UINT64 TimerTicks64;
  94   UINT64 SystemCounterVal;
  95
  96   // Calculate counter ticks that can represent requested delay:
  97   //  = MicroSeconds x TICKS_PER_MICRO_SEC
  98   //  = MicroSeconds x Frequency.10^-6
  99   TimerTicks64 = ((UINT64)MicroSeconds * PcdGet32 (PcdArmArchTimerFreqInHz)) / 1000000U;
 100
 101   // Read System Counter value
 102   SystemCounterVal = ArmGenericTimerGetSystemCount ();
 103
 104   TimerTicks64 += SystemCounterVal;
 105
 106   // Wait until delay count is expired.
 107   while (SystemCounterVal < TimerTicks64) {
 108     SystemCounterVal = ArmGenericTimerGetSystemCount ();
 109   }
 110
 111   return MicroSeconds;
 112 }
 113
 114
 115 /**
 116   Stalls the CPU for at least the given number of nanoseconds.
 117
 118   Stalls the CPU for the number of nanoseconds specified by NanoSeconds.
 119
 120   When the timer frequency is 1MHz, each tick corresponds to 1 microsecond.
 121   Therefore, the nanosecond delay will be rounded up to the nearest 1 microsecond.
 122
 123   @param  NanoSeconds The minimum number of nanoseconds to delay.
 124
 125   @return The value of NanoSeconds inputed.
 126
 127 **/
 128 UINTN
 129 EFIAPI
 130 NanoSecondDelay (
 131   IN  UINTN NanoSeconds
 132   )
 133 {
 134   UINTN  MicroSeconds;
 135
 136   // Round up to 1us Tick Number
 137   MicroSeconds = NanoSeconds / 1000;
 138   MicroSeconds += ((NanoSeconds % 1000) == 0) ? 0 : 1;
 139
 140   MicroSecondDelay (MicroSeconds);
 141
 142   return NanoSeconds;
 143 }
 144
 145 /**
 146   Retrieves the current value of a 64-bit free running performance counter.
 147
 148   The counter can either count up by 1 or count down by 1. If the physical
 149   performance counter counts by a larger increment, then the counter values
 150   must be translated. The properties of the counter can be retrieved from
 151   GetPerformanceCounterProperties().
 152
 153   @return The current value of the free running performance counter.
 154
 155 **/
 156 UINT64
 157 EFIAPI
 158 GetPerformanceCounter (
 159   VOID
 160   )
 161 {
 162   // Just return the value of system count
 163   return ArmGenericTimerGetSystemCount ();
 164 }
 165
 166 /**
 167   Retrieves the 64-bit frequency in Hz and the range of performance counter
 168   values.
 169
 170   If StartValue is not NULL, then the value that the performance counter starts
 171   with immediately after is it rolls over is returned in StartValue. If
 172   EndValue is not NULL, then the value that the performance counter end with
 173   immediately before it rolls over is returned in EndValue. The 64-bit
 174   frequency of the performance counter in Hz is always returned. If StartValue
 175   is less than EndValue, then the performance counter counts up. If StartValue
 176   is greater than EndValue, then the performance counter counts down. For
 177   example, a 64-bit free running counter that counts up would have a StartValue
 178   of 0 and an EndValue of 0xFFFFFFFFFFFFFFFF. A 24-bit free running counter
 179   that counts down would have a StartValue of 0xFFFFFF and an EndValue of 0.
 180
 181   @param  StartValue  The value the performance counter starts with when it
 182                       rolls over.
 183   @param  EndValue    The value that the performance counter ends with before
 184                       it rolls over.
 185
 186   @return The frequency in Hz.
 187
 188 **/
 189 UINT64
 190 EFIAPI
 191 GetPerformanceCounterProperties (
 192   OUT      UINT64                    *StartValue,  OPTIONAL
 193   OUT      UINT64                    *EndValue     OPTIONAL
 194   )
 195 {
 196   if (StartValue != NULL) {
 197     // Timer starts with the reload value
 198     *StartValue = (UINT64)0ULL ;
 199   }
 200
 201   if (EndValue != NULL) {
 202     // Timer counts down to 0x0
 203     *EndValue = 0xFFFFFFFFFFFFFFFFUL;
 204   }
 205
 206   return (UINT64)ArmGenericTimerGetTimerFreq ();
 207 }