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

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

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Hi Ray,

Can you please help to review this patch again?


Thanks,
Chao
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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