ArmPkg/Library/ArmArchTimerLib/ArmArchTimerLib.c

   1 /** @file
   2   Generic ARM implementation of TimerLib.h
   3
   4   Copyright (c) 2011-2016, 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 // Select appropriate multiply function for platform architecture.
  28 #ifdef MDE_CPU_ARM
  29 #define MultU64xN MultU64x32
  30 #else
  31 #define MultU64xN MultU64x64
  32 #endif
  33
  34
  35 RETURN_STATUS
  36 EFIAPI
  37 TimerConstructor (
  38   VOID
  39   )
  40 {
  41   //
  42   // Check if the ARM Generic Timer Extension is implemented.
  43   //
  44   if (ArmIsArchTimerImplemented ()) {
  45
  46     //
  47     // Check if Architectural Timer frequency is pre-determined by the platform
  48     // (ie. nonzero).
  49     //
  50     if (PcdGet32 (PcdArmArchTimerFreqInHz) != 0) {
  51       //
  52       // Check if ticks/uS is not 0. The Architectural timer runs at constant
  53       // frequency, irrespective of CPU frequency. According to Generic Timer
  54       // Ref manual, lower bound of the frequency is in the range of 1-10MHz.
  55       //
  56       ASSERT (TICKS_PER_MICRO_SEC);
  57
  58 #ifdef MDE_CPU_ARM
  59       //
  60       // Only set the frequency for ARMv7. We expect the secure firmware to
  61       // have already done it.
  62       // If the security extension is not implemented, set Timer Frequency
  63       // here.
  64       //
  65       if ((ArmReadIdPfr1 () & ARM_PFR1_SEC) == 0x0) {
  66         ArmGenericTimerSetTimerFreq (PcdGet32 (PcdArmArchTimerFreqInHz));
  67       }
  68 #endif
  69     }
  70
  71     //
  72     // Architectural Timer Frequency must be set in Secure privileged
  73     // mode (if secure extension is supported).
  74     // If the reset value (0) is returned, just ASSERT.
  75     //
  76     ASSERT (ArmGenericTimerGetTimerFreq () != 0);
  77
  78   } else {
  79     DEBUG ((EFI_D_ERROR, "ARM Architectural Timer is not available in the CPU, hence this library cannot be used.\n"));
  80     ASSERT (0);
  81   }
  82
  83   return RETURN_SUCCESS;
  84 }
  85
  86 /**
  87   A local utility function that returns the PCD value, if specified.
  88   Otherwise it defaults to ArmGenericTimerGetTimerFreq.
  89
  90   @return The timer frequency.
  91
  92 **/
  93 STATIC
  94 UINTN
  95 EFIAPI
  96 GetPlatformTimerFreq (
  97   )
  98 {
  99   UINTN TimerFreq;
 100
 101   TimerFreq = PcdGet32 (PcdArmArchTimerFreqInHz);
 102   if (TimerFreq == 0) {
 103     TimerFreq = ArmGenericTimerGetTimerFreq ();
 104   }
 105   return TimerFreq;
 106 }
 107
 108
 109 /**
 110   Stalls the CPU for the number of microseconds specified by MicroSeconds.
 111
 112   @param  MicroSeconds  The minimum number of microseconds to delay.
 113
 114   @return The value of MicroSeconds input.
 115
 116 **/
 117 UINTN
 118 EFIAPI
 119 MicroSecondDelay (
 120   IN      UINTN                     MicroSeconds
 121   )
 122 {
 123   UINT64 TimerTicks64;
 124   UINT64 SystemCounterVal;
 125
 126   // Calculate counter ticks that represent requested delay:
 127   //  = MicroSeconds x TICKS_PER_MICRO_SEC
 128   //  = MicroSeconds x Frequency.10^-6
 129   TimerTicks64 = DivU64x32 (
 130                    MultU64xN (
 131                      MicroSeconds,
 132                      GetPlatformTimerFreq ()
 133                      ),
 134                    1000000U
 135                    );
 136
 137   // Read System Counter value
 138   SystemCounterVal = ArmGenericTimerGetSystemCount ();
 139
 140   TimerTicks64 += SystemCounterVal;
 141
 142   // Wait until delay count expires.
 143   while (SystemCounterVal < TimerTicks64) {
 144     SystemCounterVal = ArmGenericTimerGetSystemCount ();
 145   }
 146
 147   return MicroSeconds;
 148 }
 149
 150
 151 /**
 152   Stalls the CPU for at least the given number of nanoseconds.
 153
 154   Stalls the CPU for the number of nanoseconds specified by NanoSeconds.
 155
 156   When the timer frequency is 1MHz, each tick corresponds to 1 microsecond.
 157   Therefore, the nanosecond delay will be rounded up to the nearest 1 microsecond.
 158
 159   @param  NanoSeconds The minimum number of nanoseconds to delay.
 160
 161   @return The value of NanoSeconds inputed.
 162
 163 **/
 164 UINTN
 165 EFIAPI
 166 NanoSecondDelay (
 167   IN  UINTN NanoSeconds
 168   )
 169 {
 170   UINTN  MicroSeconds;
 171
 172   // Round up to 1us Tick Number
 173   MicroSeconds = NanoSeconds / 1000;
 174   MicroSeconds += ((NanoSeconds % 1000) == 0) ? 0 : 1;
 175
 176   MicroSecondDelay (MicroSeconds);
 177
 178   return NanoSeconds;
 179 }
 180
 181 /**
 182   Retrieves the current value of a 64-bit free running performance counter.
 183
 184   The counter can either count up by 1 or count down by 1. If the physical
 185   performance counter counts by a larger increment, then the counter values
 186   must be translated. The properties of the counter can be retrieved from
 187   GetPerformanceCounterProperties().
 188
 189   @return The current value of the free running performance counter.
 190
 191 **/
 192 UINT64
 193 EFIAPI
 194 GetPerformanceCounter (
 195   VOID
 196   )
 197 {
 198   // Just return the value of system count
 199   return ArmGenericTimerGetSystemCount ();
 200 }
 201
 202 /**
 203   Retrieves the 64-bit frequency in Hz and the range of performance counter
 204   values.
 205
 206   If StartValue is not NULL, then the value that the performance counter starts
 207   with immediately after is it rolls over is returned in StartValue. If
 208   EndValue is not NULL, then the value that the performance counter end with
 209   immediately before it rolls over is returned in EndValue. The 64-bit
 210   frequency of the performance counter in Hz is always returned. If StartValue
 211   is less than EndValue, then the performance counter counts up. If StartValue
 212   is greater than EndValue, then the performance counter counts down. For
 213   example, a 64-bit free running counter that counts up would have a StartValue
 214   of 0 and an EndValue of 0xFFFFFFFFFFFFFFFF. A 24-bit free running counter
 215   that counts down would have a StartValue of 0xFFFFFF and an EndValue of 0.
 216
 217   @param  StartValue  The value the performance counter starts with when it
 218                       rolls over.
 219   @param  EndValue    The value that the performance counter ends with before
 220                       it rolls over.
 221
 222   @return The frequency in Hz.
 223
 224 **/
 225 UINT64
 226 EFIAPI
 227 GetPerformanceCounterProperties (
 228   OUT      UINT64                    *StartValue,  OPTIONAL
 229   OUT      UINT64                    *EndValue     OPTIONAL
 230   )
 231 {
 232   if (StartValue != NULL) {
 233     // Timer starts at 0
 234     *StartValue = (UINT64)0ULL ;
 235   }
 236
 237   if (EndValue != NULL) {
 238     // Timer counts up.
 239     *EndValue = 0xFFFFFFFFFFFFFFFFUL;
 240   }
 241
 242   return (UINT64)ArmGenericTimerGetTimerFreq ();
 243 }
 244
 245 /**
 246   Converts elapsed ticks of performance counter to time in nanoseconds.
 247
 248   This function converts the elapsed ticks of running performance counter to
 249   time value in unit of nanoseconds.
 250
 251   @param  Ticks     The number of elapsed ticks of running performance counter.
 252
 253   @return The elapsed time in nanoseconds.
 254
 255 **/
 256 UINT64
 257 EFIAPI
 258 GetTimeInNanoSecond (
 259   IN      UINT64                     Ticks
 260   )
 261 {
 262   UINT64  NanoSeconds;
 263   UINT32  Remainder;
 264   UINT32  TimerFreq;
 265
 266   TimerFreq = GetPlatformTimerFreq ();
 267   //
 268   //          Ticks
 269   // Time = --------- x 1,000,000,000
 270   //        Frequency
 271   //
 272   NanoSeconds = MultU64xN (
 273                   DivU64x32Remainder (
 274                     Ticks,
 275                     TimerFreq,
 276                     &Remainder),
 277                   1000000000U
 278                   );
 279
 280   //
 281   // Frequency < 0x100000000, so Remainder < 0x100000000, then (Remainder * 1,000,000,000)
 282   // will not overflow 64-bit.
 283   //
 284   NanoSeconds += DivU64x32 (
 285                    MultU64xN (
 286                      (UINT64) Remainder,
 287                      1000000000U),
 288                    TimerFreq
 289                    );
 290
 291   return NanoSeconds;
 292 }