ArmPkg/Library/ArmArchTimerLib/ArmArchTimerLib.c

   1 /** @file
   2   Generic ARM implementation of TimerLib.h
   3
   4   Copyright (c) 2011-2012, 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/BaseLib.h>
  19 #include <Library/TimerLib.h>
  20 #include <Library/DebugLib.h>
  21 #include <Library/PcdLib.h>
  22 #include <Library/ArmArchTimerLib.h>
  23 #include <Chipset/ArmV7.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 () & 0xF0) == 0x0) {
  50       ArmArchTimerSetTimerFreq (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 = ArmArchTimerGetTimerFreq ();
  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   TimerTicks64 = MultU64x32 (MicroSeconds, TICKS_PER_MICRO_SEC);
  87
  88   // Read System Counter value
  89   SystemCounterVal = ArmArchTimerGetSystemCount ();
  90
  91   TimerTicks64 += SystemCounterVal;
  92
  93   // Wait until delay count is expired.
  94   while (SystemCounterVal < TimerTicks64) {
  95     SystemCounterVal = ArmArchTimerGetSystemCount ();
  96   }
  97
  98   return MicroSeconds;
  99 }
 100
 101
 102 /**
 103   Stalls the CPU for at least the given number of nanoseconds.
 104
 105   Stalls the CPU for the number of nanoseconds specified by NanoSeconds.
 106
 107   When the timer frequency is 1MHz, each tick corresponds to 1 microsecond.
 108   Therefore, the nanosecond delay will be rounded up to the nearest 1 microsecond.
 109
 110   @param  NanoSeconds The minimum number of nanoseconds to delay.
 111
 112   @return The value of NanoSeconds inputed.
 113
 114 **/
 115 UINTN
 116 EFIAPI
 117 NanoSecondDelay (
 118   IN  UINTN NanoSeconds
 119   )
 120 {
 121   UINTN  MicroSeconds;
 122
 123   // Round up to 1us Tick Number
 124   MicroSeconds = NanoSeconds / 1000;
 125   MicroSeconds += ((NanoSeconds % 1000) == 0) ? 0 : 1;
 126
 127   MicroSecondDelay (MicroSeconds);
 128
 129   return NanoSeconds;
 130 }
 131
 132 /**
 133   Retrieves the current value of a 64-bit free running performance counter.
 134
 135   The counter can either count up by 1 or count down by 1. If the physical
 136   performance counter counts by a larger increment, then the counter values
 137   must be translated. The properties of the counter can be retrieved from
 138   GetPerformanceCounterProperties().
 139
 140   @return The current value of the free running performance counter.
 141
 142 **/
 143 UINT64
 144 EFIAPI
 145 GetPerformanceCounter (
 146   VOID
 147   )
 148 {
 149   // Just return the value of system count
 150   return ArmArchTimerGetSystemCount ();
 151 }
 152
 153 /**
 154   Retrieves the 64-bit frequency in Hz and the range of performance counter
 155   values.
 156
 157   If StartValue is not NULL, then the value that the performance counter starts
 158   with immediately after is it rolls over is returned in StartValue. If
 159   EndValue is not NULL, then the value that the performance counter end with
 160   immediately before it rolls over is returned in EndValue. The 64-bit
 161   frequency of the performance counter in Hz is always returned. If StartValue
 162   is less than EndValue, then the performance counter counts up. If StartValue
 163   is greater than EndValue, then the performance counter counts down. For
 164   example, a 64-bit free running counter that counts up would have a StartValue
 165   of 0 and an EndValue of 0xFFFFFFFFFFFFFFFF. A 24-bit free running counter
 166   that counts down would have a StartValue of 0xFFFFFF and an EndValue of 0.
 167
 168   @param  StartValue  The value the performance counter starts with when it
 169                       rolls over.
 170   @param  EndValue    The value that the performance counter ends with before
 171                       it rolls over.
 172
 173   @return The frequency in Hz.
 174
 175 **/
 176 UINT64
 177 EFIAPI
 178 GetPerformanceCounterProperties (
 179   OUT      UINT64                    *StartValue,  OPTIONAL
 180   OUT      UINT64                    *EndValue     OPTIONAL
 181   )
 182 {
 183   if (StartValue != NULL) {
 184     // Timer starts with the reload value
 185     *StartValue = (UINT64)0ULL ;
 186   }
 187
 188   if (EndValue != NULL) {
 189     // Timer counts down to 0x0
 190     *EndValue = 0xFFFFFFFFFFFFFFFFUL;
 191   }
 192
 193   return (UINT64)ArmArchTimerGetTimerFreq ();
 194 }