[edk2-devel] [PATCH v2 05/13] UefiCpuPkg: Add LoongArch64 CPU Timer instance

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

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=4734

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   |  15 +-
 .../CpuTimerLib/LoongArch64/CpuTimerLib.c     | 250 ++++++++++++++++++
 UefiCpuPkg/UefiCpuPkg.dsc                     |   3 +
 3 files changed, 266 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 f0f4ae902a..4a1c7c0510 100644
--- a/UefiCpuPkg/Library/CpuTimerLib/BaseCpuTimerLib.inf
+++ b/UefiCpuPkg/Library/CpuTimerLib/BaseCpuTimerLib.inf
@@ -1,10 +1,15 @@
 ## @file
 #  Base CPU Timer Library
 #
-#  Provides basic timer support using CPUID Leaf 0x15 XTAL frequency. The performance
+#  Provides basic timer support.
+#
+#  In x86, using CPUID Leaf 0x15 XTAL frequency. The performance
 #  counter features are provided by the processors time stamp counter.
 #
+#  In LoongArch64, using CPUCFG 0x4 and 0x5 for Stable Counter frequency.
+#
 #  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
 #
 ##
@@ -18,10 +23,13 @@ [Defines]
   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
@@ -31,5 +39,8 @@ [LibraryClasses]
   DebugLib
   PcdLib
 
+[LibraryClasses.LoongArch64]
+  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..4ca60cdaeb
--- /dev/null
+++ b/UefiCpuPkg/Library/CpuTimerLib/LoongArch64/CpuTimerLib.c
@@ -0,0 +1,250 @@
+/** @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);
+
+  ASSERT (StableTimerFreq != 0);
+
+  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
+             );
+  ASSERT_RETURN_ERROR (Status);
+
+  //
+  // 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;
+}
diff --git a/UefiCpuPkg/UefiCpuPkg.dsc b/UefiCpuPkg/UefiCpuPkg.dsc
index 10b33594e5..2eebd45125 100644
--- a/UefiCpuPkg/UefiCpuPkg.dsc
+++ b/UefiCpuPkg/UefiCpuPkg.dsc
@@ -110,6 +110,9 @@ [LibraryClasses.common.UEFI_APPLICATION]
   UefiApplicationEntryPoint|MdePkg/Library/UefiApplicationEntryPoint/UefiApplicationEntryPoint.inf
   MemoryAllocationLib|MdePkg/Library/UefiMemoryAllocationLib/UefiMemoryAllocationLib.inf
 
+[LibraryClasses.LoongArch64]
+  SafeIntLib|MdePkg/Library/BaseSafeIntLib/BaseSafeIntLib.inf
+
 #
 # Drivers/Libraries within this package
 #
-- 
2.27.0



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