Re: [edk2-devel] [PATCH v8 11/37] UefiCpuPkg: Add LoongArch64 CPU Timer instance

["Chao Li" <lichao@loongson.cn>]

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Hi Ray and Laszlo,

I would very much like to be merged into stable202302, the soft feature 
deadline is 2024-02-05, so could you please hlep to review this patch as 
soon as passable? Please...


Thanks,
Chao
On 2024/1/31 11:30, Chao Li wrote:
>
> Hi Ray,
>
> Can you please help to review this patch again?
>
> On 2024/1/26 14:29, Chao Li wrote:
>> Add the LoongArch64 CPU Timer instance to CpuTimerLib, using CPUCFG 0x4
>> and 0x5 for Stable Counter frequency.
>>
>> BZ:https://bugzilla.tianocore.org/show_bug.cgi?id=4584
>>
>> Cc: Eric Dong<eric.dong@intel.com>
>> Cc: Ray Ni<ray.ni@intel.com>
>> Cc: Rahul Kumar<rahul1.kumar@intel.com>
>> Cc: Gerd Hoffmann<kraxel@redhat.com>
>> Signed-off-by: Chao Li<lichao@loongson.cn>
>> ---
>>   .../Library/CpuTimerLib/BaseCpuTimerLib.inf   |   9 +-
>>   .../CpuTimerLib/LoongArch64/CpuTimerLib.c     | 251 ++++++++++++++++++
>>   2 files changed, 258 insertions(+), 2 deletions(-)
>>   create mode 100644 UefiCpuPkg/Library/CpuTimerLib/LoongArch64/CpuTimerLib.c
>>
>> diff --git a/UefiCpuPkg/Library/CpuTimerLib/BaseCpuTimerLib.inf b/UefiCpuPkg/Library/CpuTimerLib/BaseCpuTimerLib.inf
>> index de0648de91..7e6152ef7e 100644
>> --- a/UefiCpuPkg/Library/CpuTimerLib/BaseCpuTimerLib.inf
>> +++ b/UefiCpuPkg/Library/CpuTimerLib/BaseCpuTimerLib.inf
>> @@ -5,6 +5,7 @@
>>   #  counter features are provided by the processors time stamp counter.
>>   #
>>   #  Copyright (c) 2021, Intel Corporation. All rights reserved.<BR>
>> +#  Copyright (c) 2024, Loongson Technology Corporation Limited. All rights reserved.<BR>
>>   #  SPDX-License-Identifier: BSD-2-Clause-Patent
>>   #
>>   ##
>> @@ -18,18 +19,22 @@
>>     LIBRARY_CLASS                  = TimerLib
>>     MODULE_UNI_FILE                = BaseCpuTimerLib.uni
>>   
>> -[Sources]
>> +[Sources.IA32, Sources.X64]
>>     CpuTimerLib.c
>>     BaseCpuTimerLib.c
>>   
>> +[Sources.LOONGARCH64]
>> +  LoongArch64/CpuTimerLib.c
>> +
>>   [Packages]
>>     MdePkg/MdePkg.dec
>>     UefiCpuPkg/UefiCpuPkg.dec
>>   
>>   [LibraryClasses]
>>     BaseLib
>> -  PcdLib
>>     DebugLib
>> +  PcdLib
>> +  SafeIntLib
>>   
>>   [Pcd]
>>     gUefiCpuPkgTokenSpaceGuid.PcdCpuCoreCrystalClockFrequency  ## CONSUMES
>> diff --git a/UefiCpuPkg/Library/CpuTimerLib/LoongArch64/CpuTimerLib.c b/UefiCpuPkg/Library/CpuTimerLib/LoongArch64/CpuTimerLib.c
>> new file mode 100644
>> index 0000000000..a5ae8d0185
>> --- /dev/null
>> +++ b/UefiCpuPkg/Library/CpuTimerLib/LoongArch64/CpuTimerLib.c
>> @@ -0,0 +1,251 @@
>> +/** @file
>> +  CPUCFG 0x4 and 0x5 for Stable Counter frequency instance of Timer Library.
>> +
>> +  Copyright (c) 2024, Loongson Technology Corporation Limited. All rights reserved.<BR>
>> +
>> +  SPDX-License-Identifier: BSD-2-Clause-Patent
>> +**/
>> +
>> +#include <Base.h>
>> +#include <Library/BaseLib.h>
>> +#include <Library/DebugLib.h>
>> +#include <Library/SafeIntLib.h>
>> +#include <Library/TimerLib.h>
>> +#include <Register/LoongArch64/Cpucfg.h>
>> +
>> +/**
>> +  Calculate clock frequency using CPUCFG 0x4 and 0x5 registers.
>> +
>> +  @param  VOID.
>> +
>> +  @return The frequency in Hz.
>> +
>> +**/
>> +STATIC
>> +UINT64
>> +CalcConstFreq (
>> +  VOID
>> +  )
>> +{
>> +  UINT32                 BaseFreq;
>> +  UINT64                 ClockMultiplier;
>> +  UINT32                 ClockDivide;
>> +  CPUCFG_REG4_INFO_DATA  CcFreq;
>> +  CPUCFG_REG5_INFO_DATA  CpucfgReg5Data;
>> +  UINT64                 StableTimerFreq;
>> +
>> +  //
>> +  // Get the the crystal frequency corresponding to the constant
>> +  // frequency timer and the clock used by the timer.
>> +  //
>> +  AsmCpucfg (CPUCFG_REG4_INFO, &CcFreq.Uint32);
>> +
>> +  //
>> +  // Get the multiplication factor and frequency division factor
>> +  // corresponding to the constant frequency timer and the clock
>> +  // used by the timer.
>> +  //
>> +  AsmCpucfg (CPUCFG_REG5_INFO, &CpucfgReg5Data.Uint32);
>> +
>> +  BaseFreq        = CcFreq.Bits.CC_FREQ;
>> +  ClockMultiplier = CpucfgReg5Data.Bits.CC_MUL & 0xFFFF;
>> +  ClockDivide     = CpucfgReg5Data.Bits.CC_DIV & 0xFFFF;
>> +
>> +  if ((BaseFreq == 0x0) || (ClockMultiplier == 0x0) || (ClockDivide == 0x0)) {
>> +    DEBUG ((
>> +      DEBUG_ERROR,
>> +      "LoongArch Stable Timer is not available in the CPU, hence this library cannot be used.\n"
>> +      ));
>> +    ASSERT (FALSE);
>> +    CpuDeadLoop ();
>> +  }
>> +
>> +  StableTimerFreq = ((ClockMultiplier * BaseFreq) / ClockDivide);
>> +
>> +  if (StableTimerFreq == 0x0) {
>> +    ASSERT (FALSE);
>> +  }
>> +
>> +  return StableTimerFreq;
>> +}
>> +
>> +/**
>> +  Stalls the CPU for at least the given number of microseconds.
>> +
>> +  Stalls the CPU for the number of microseconds specified by MicroSeconds.
>> +
>> +  @param  MicroSeconds  The minimum number of microseconds to delay.
>> +
>> +  @return MicroSeconds
>> +
>> +**/
>> +UINTN
>> +EFIAPI
>> +MicroSecondDelay (
>> +  IN UINTN  MicroSeconds
>> +  )
>> +{
>> +  UINT64         CurrentTicks, ExceptedTicks, Remaining;
>> +  RETURN_STATUS  Status;
>> +
>> +  Status = SafeUint64Mult (MicroSeconds, CalcConstFreq (), &Remaining);
>> +  ASSERT_RETURN_ERROR (Status);
>> +
>> +  ExceptedTicks  = DivU64x32 (Remaining, 1000000U);
>> +  CurrentTicks   = AsmReadStableCounter ();
>> +  ExceptedTicks += CurrentTicks;
>> +
>> +  do {
>> +    CurrentTicks = AsmReadStableCounter ();
>> +  } while (CurrentTicks < ExceptedTicks);
>> +
>> +  return MicroSeconds;
>> +}
>> +
>> +/**
>> +  Stalls the CPU for at least the given number of nanoseconds.
>> +
>> +  Stalls the CPU for the number of nanoseconds specified by NanoSeconds.
>> +
>> +  @param  NanoSeconds The minimum number of nanoseconds to delay.
>> +
>> +  @return NanoSeconds
>> +
>> +**/
>> +UINTN
>> +EFIAPI
>> +NanoSecondDelay (
>> +  IN UINTN  NanoSeconds
>> +  )
>> +{
>> +  UINTN  MicroSeconds;
>> +
>> +  // Round up to 1us Tick Number
>> +  MicroSeconds  = NanoSeconds / 1000;
>> +  MicroSeconds += ((NanoSeconds % 1000) == 0) ? 0 : 1;
>> +
>> +  MicroSecondDelay (MicroSeconds);
>> +
>> +  return NanoSeconds;
>> +}
>> +
>> +/**
>> +  Retrieves the current value of a 64-bit free running Stable Counter.
>> +
>> +  The LoongArch defines a constant frequency timer, whose main body is a
>> +  64-bit counter called StableCounter. StableCounter is set to 0 after
>> +  reset, and then increments by 1 every counting clock cycle. When the
>> +  count reaches all 1s, it automatically wraps around to 0 and continues
>> +  to increment.
>> +  The properties of the Stable Counter can be retrieved from
>> +  GetPerformanceCounterProperties().
>> +
>> +  @return The current value of the Stable Counter.
>> +
>> +**/
>> +UINT64
>> +EFIAPI
>> +GetPerformanceCounter (
>> +  VOID
>> +  )
>> +{
>> +  //
>> +  // Just return the value of Stable Counter.
>> +  //
>> +  return AsmReadStableCounter ();
>> +}
>> +
>> +/**
>> +  Retrieves the 64-bit frequency in Hz and the range of Stable Counter
>> +  values.
>> +
>> +  If StartValue is not NULL, then the value that the stbale counter starts
>> +  with immediately after is it rolls over is returned in StartValue. If
>> +  EndValue is not NULL, then the value that the stable counter end with
>> +  immediately before it rolls over is returned in EndValue. The 64-bit
>> +  frequency of the system frequency in Hz is always returned.
>> +
>> +  @param  StartValue  The value the stable counter starts with when it
>> +                      rolls over.
>> +  @param  EndValue    The value that the stable counter ends with before
>> +                      it rolls over.
>> +
>> +  @return The frequency in Hz.
>> +
>> +**/
>> +UINT64
>> +EFIAPI
>> +GetPerformanceCounterProperties (
>> +  OUT UINT64  *StartValue   OPTIONAL,
>> +  OUT UINT64  *EndValue     OPTIONAL
>> +  )
>> +{
>> +  if (StartValue != NULL) {
>> +    *StartValue = 0;
>> +  }
>> +
>> +  if (EndValue != NULL) {
>> +    *EndValue = 0xFFFFFFFFFFFFFFFFULL;
>> +  }
>> +
>> +  return CalcConstFreq ();
>> +}
>> +
>> +/**
>> +  Converts elapsed ticks of performance counter to time in nanoseconds.
>> +
>> +  This function converts the elapsed ticks of running performance counter to
>> +  time value in unit of nanoseconds.
>> +
>> +  @param  Ticks     The number of elapsed ticks of running performance counter.
>> +
>> +  @return The elapsed time in nanoseconds.
>> +
>> +**/
>> +UINT64
>> +EFIAPI
>> +GetTimeInNanoSecond (
>> +  IN UINT64  Ticks
>> +  )
>> +{
>> +  UINT64         Frequency;
>> +  UINT64         NanoSeconds;
>> +  UINT64         Remainder;
>> +  INTN           Shift;
>> +  RETURN_STATUS  Status;
>> +
>> +  Frequency = GetPerformanceCounterProperties (NULL, NULL);
>> +
>> +  //
>> +  //          Ticks
>> +  // Time = --------- x 1,000,000,000
>> +  //        Frequency
>> +  //
>> +  Status = SafeUint64Mult (
>> +             DivU64x64Remainder (Ticks, Frequency, &Remainder),
>> +             1000000000u,
>> +             &NanoSeconds
>> +             );
>> +
>> +  //
>> +  // Ensure (Remainder * 1,000,000,000) will not overflow 64-bit.
>> +  // Since 2^29 < 1,000,000,000 = 0x3B9ACA00 < 2^30, Remainder should < 2^(64-30) = 2^34,
>> +  // i.e. highest bit set in Remainder should <= 33.
>> +  //
>> +  Shift     = MAX (0, HighBitSet64 (Remainder) - 33);
>> +  Remainder = RShiftU64 (Remainder, (UINTN)Shift);
>> +  Frequency = RShiftU64 (Frequency, (UINTN)Shift);
>> +
>> +  Status = SafeUint64Add (
>> +             NanoSeconds,
>> +             DivU64x64Remainder (
>> +               MultU64x32 (Remainder, 1000000000u),
>> +               Frequency,
>> +               NULL
>> +               ),
>> +             &NanoSeconds
>> +             );
>> +  ASSERT_RETURN_ERROR (Status);
>> +
>> +  return NanoSeconds;
>> +}
> 


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