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 pre-determined by the platform
  41     // (ie. nonzero).
  42     //
  43     if (PcdGet32 (PcdArmArchTimerFreqInHz) != 0) {
  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     //
  65     // Architectural Timer Frequency must be set in the Secure privileged
  66     // mode (if secure extension is supported).
  67     // If the reset value (0) is returned, just ASSERT.
  68     //
  69     TimerFreq = ArmGenericTimerGetTimerFreq ();
  70     ASSERT (TimerFreq != 0);
  71   } else {
  72     DEBUG ((EFI_D_ERROR, "ARM Architectural Timer is not available in the CPU, hence this library can not be used.\n"));
  73     ASSERT (0);
  74   }
  75
  76   return RETURN_SUCCESS;
  77 }
  78
  79
  80 /**
  81   Stalls the CPU for the number of microseconds specified by MicroSeconds.
  82
  83   @param  MicroSeconds  The minimum number of microseconds to delay.
  84
  85   @return The value of MicroSeconds inputted.
  86
  87 **/
  88 UINTN
  89 EFIAPI
  90 MicroSecondDelay (
  91   IN      UINTN                     MicroSeconds
  92   )
  93 {
  94   UINT64 TimerTicks64;
  95   UINT64 SystemCounterVal;
  96   UINT64 (EFIAPI
  97           *MultU64xN) (
  98             IN UINT64 Multiplicand,
  99             IN UINTN  Multiplier
 100             );
 101   UINTN TimerFreq;
 102
 103 #ifdef MDE_CPU_ARM
 104   MultU64xN = MultU64x32;
 105 #else
 106   MultU64xN = MultU64x64;
 107 #endif
 108
 109   TimerFreq = PcdGet32 (PcdArmArchTimerFreqInHz);
 110   if (TimerFreq == 0) {
 111     TimerFreq = ArmGenericTimerGetTimerFreq ();
 112   }
 113
 114   // Calculate counter ticks that can represent requested delay:
 115   //  = MicroSeconds x TICKS_PER_MICRO_SEC
 116   //  = MicroSeconds x Frequency.10^-6
 117   TimerTicks64 = DivU64x32 (
 118                    MultU64xN (
 119                      MicroSeconds,
 120                      TimerFreq
 121                      ),
 122                    1000000U
 123                    );
 124
 125   // Read System Counter value
 126   SystemCounterVal = ArmGenericTimerGetSystemCount ();
 127
 128   TimerTicks64 += SystemCounterVal;
 129
 130   // Wait until delay count is expired.
 131   while (SystemCounterVal < TimerTicks64) {
 132     SystemCounterVal = ArmGenericTimerGetSystemCount ();
 133   }
 134
 135   return MicroSeconds;
 136 }
 137
 138
 139 /**
 140   Stalls the CPU for at least the given number of nanoseconds.
 141
 142   Stalls the CPU for the number of nanoseconds specified by NanoSeconds.
 143
 144   When the timer frequency is 1MHz, each tick corresponds to 1 microsecond.
 145   Therefore, the nanosecond delay will be rounded up to the nearest 1 microsecond.
 146
 147   @param  NanoSeconds The minimum number of nanoseconds to delay.
 148
 149   @return The value of NanoSeconds inputed.
 150
 151 **/
 152 UINTN
 153 EFIAPI
 154 NanoSecondDelay (
 155   IN  UINTN NanoSeconds
 156   )
 157 {
 158   UINTN  MicroSeconds;
 159
 160   // Round up to 1us Tick Number
 161   MicroSeconds = NanoSeconds / 1000;
 162   MicroSeconds += ((NanoSeconds % 1000) == 0) ? 0 : 1;
 163
 164   MicroSecondDelay (MicroSeconds);
 165
 166   return NanoSeconds;
 167 }
 168
 169 /**
 170   Retrieves the current value of a 64-bit free running performance counter.
 171
 172   The counter can either count up by 1 or count down by 1. If the physical
 173   performance counter counts by a larger increment, then the counter values
 174   must be translated. The properties of the counter can be retrieved from
 175   GetPerformanceCounterProperties().
 176
 177   @return The current value of the free running performance counter.
 178
 179 **/
 180 UINT64
 181 EFIAPI
 182 GetPerformanceCounter (
 183   VOID
 184   )
 185 {
 186   // Just return the value of system count
 187   return ArmGenericTimerGetSystemCount ();
 188 }
 189
 190 /**
 191   Retrieves the 64-bit frequency in Hz and the range of performance counter
 192   values.
 193
 194   If StartValue is not NULL, then the value that the performance counter starts
 195   with immediately after is it rolls over is returned in StartValue. If
 196   EndValue is not NULL, then the value that the performance counter end with
 197   immediately before it rolls over is returned in EndValue. The 64-bit
 198   frequency of the performance counter in Hz is always returned. If StartValue
 199   is less than EndValue, then the performance counter counts up. If StartValue
 200   is greater than EndValue, then the performance counter counts down. For
 201   example, a 64-bit free running counter that counts up would have a StartValue
 202   of 0 and an EndValue of 0xFFFFFFFFFFFFFFFF. A 24-bit free running counter
 203   that counts down would have a StartValue of 0xFFFFFF and an EndValue of 0.
 204
 205   @param  StartValue  The value the performance counter starts with when it
 206                       rolls over.
 207   @param  EndValue    The value that the performance counter ends with before
 208                       it rolls over.
 209
 210   @return The frequency in Hz.
 211
 212 **/
 213 UINT64
 214 EFIAPI
 215 GetPerformanceCounterProperties (
 216   OUT      UINT64                    *StartValue,  OPTIONAL
 217   OUT      UINT64                    *EndValue     OPTIONAL
 218   )
 219 {
 220   if (StartValue != NULL) {
 221     // Timer starts with the reload value
 222     *StartValue = (UINT64)0ULL ;
 223   }
 224
 225   if (EndValue != NULL) {
 226     // Timer counts down to 0x0
 227     *EndValue = 0xFFFFFFFFFFFFFFFFUL;
 228   }
 229
 230   return (UINT64)ArmGenericTimerGetTimerFreq ();
 231 }