[edk2-staging/RiscV64QemuVirt PATCH 14/29] UefiCpuPkg/CpuTimerLib: Add support for RISC-V

["Sunil V L" <sunilvl@ventanamicro.com>]

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=4076

This is mostly copied from
edk2-platforms/Silicon/RISC-V/ProcessorPkg/Library/RiscVTimerLib

Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Rahul Kumar <rahul1.kumar@intel.com>
Cc: Daniel Schaefer <git@danielschaefer.me>
Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
---
 .../Library/CpuTimerLib/BaseCpuTimerLib.inf   |   3 +
 .../Library/CpuTimerLib/RiscV64/CpuTimerLib.c | 199 ++++++++++++++++++
 2 files changed, 202 insertions(+)
 create mode 100644 UefiCpuPkg/Library/CpuTimerLib/RiscV64/CpuTimerLib.c

diff --git a/UefiCpuPkg/Library/CpuTimerLib/BaseCpuTimerLib.inf b/UefiCpuPkg/Library/CpuTimerLib/BaseCpuTimerLib.inf
index a22457b44940..554ce9fe9db8 100644
--- a/UefiCpuPkg/Library/CpuTimerLib/BaseCpuTimerLib.inf
+++ b/UefiCpuPkg/Library/CpuTimerLib/BaseCpuTimerLib.inf
@@ -22,6 +22,9 @@ [Sources.IA32, Sources.X64]
   Ia32_X64/CpuTimerLib.c
   Ia32_X64/BaseCpuTimerLib.c
 
+[Sources.RISCV64]
+  RiscV64/CpuTimerLib.c
+
 [Packages]
   MdePkg/MdePkg.dec
   UefiCpuPkg/UefiCpuPkg.dec
diff --git a/UefiCpuPkg/Library/CpuTimerLib/RiscV64/CpuTimerLib.c b/UefiCpuPkg/Library/CpuTimerLib/RiscV64/CpuTimerLib.c
new file mode 100644
index 000000000000..9c8efc0f3530
--- /dev/null
+++ b/UefiCpuPkg/Library/CpuTimerLib/RiscV64/CpuTimerLib.c
@@ -0,0 +1,199 @@
+/** @file
+  RISC-V instance of Timer Library.
+
+  Copyright (c) 2016 - 2022, Hewlett Packard Enterprise Development LP. All rights reserved.<BR>
+
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#include <Uefi.h>
+#include <Library/BaseLib.h>
+#include <Library/DebugLib.h>
+#include <Library/PcdLib.h>
+#include <Register/RiscV64/RiscVImpl.h>
+
+/**
+  Stalls the CPU for at least the given number of ticks.
+
+  Stalls the CPU for at least the given number of ticks. It's invoked by
+  MicroSecondDelay() and NanoSecondDelay().
+
+  @param  Delay     A period of time to delay in ticks.
+
+**/
+VOID
+InternalRiscVTimerDelay (
+  IN UINT32  Delay
+  )
+{
+  UINT32  Ticks;
+  UINT32  Times;
+
+  Times  = Delay >> (RISCV_TIMER_COMPARE_BITS - 2);
+  Delay &= ((1 << (RISCV_TIMER_COMPARE_BITS - 2)) - 1);
+  do {
+    //
+    // The target timer count is calculated here
+    //
+    Ticks = RiscVReadTimer () + Delay;
+    Delay = 1 << (RISCV_TIMER_COMPARE_BITS - 2);
+    while (((Ticks - RiscVReadTimer ()) & (1 << (RISCV_TIMER_COMPARE_BITS - 1))) == 0) {
+      CpuPause ();
+    }
+  } while (Times-- > 0);
+}
+
+/**
+  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
+  )
+{
+  InternalRiscVTimerDelay (
+    (UINT32)DivU64x32 (
+              MultU64x32 (
+                MicroSeconds,
+                PcdGet64 (PcdCpuCoreCrystalClockFrequency)
+                ),
+              1000000u
+              )
+    );
+  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
+  )
+{
+  InternalRiscVTimerDelay (
+    (UINT32)DivU64x32 (
+              MultU64x32 (
+                NanoSeconds,
+                PcdGet64 (PcdCpuCoreCrystalClockFrequency)
+                ),
+              1000000000u
+              )
+    );
+  return NanoSeconds;
+}
+
+/**
+  Retrieves the current value of a 64-bit free running performance counter.
+
+  Retrieves the current value of a 64-bit free running performance counter. The
+  counter can either count up by 1 or count down by 1. If the physical
+  performance counter counts by a larger increment, then the counter values
+  must be translated. The properties of the counter can be retrieved from
+  GetPerformanceCounterProperties().
+
+  @return The current value of the free running performance counter.
+
+**/
+UINT64
+EFIAPI
+GetPerformanceCounter (
+  VOID
+  )
+{
+  return (UINT64)RiscVReadTimer ();
+}
+
+/**return
+  Retrieves the 64-bit frequency in Hz and the range of performance counter
+  values.
+
+  If StartValue is not NULL, then the value that the performance counter starts
+  with immediately after is it rolls over is returned in StartValue. If
+  EndValue is not NULL, then the value that the performance counter end with
+  immediately before it rolls over is returned in EndValue. The 64-bit
+  frequency of the performance counter in Hz is always returned. If StartValue
+  is less than EndValue, then the performance counter counts up. If StartValue
+  is greater than EndValue, then the performance counter counts down. For
+  example, a 64-bit free running counter that counts up would have a StartValue
+  of 0 and an EndValue of 0xFFFFFFFFFFFFFFFF. A 24-bit free running counter
+  that counts down would have a StartValue of 0xFFFFFF and an EndValue of 0.
+
+  @param  StartValue  The value the performance counter starts with when it
+                      rolls over.
+  @param  EndValue    The value that the performance 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 = 32 - 1;
+  }
+
+  return PcdGet64 (PcdCpuCoreCrystalClockFrequency);
+}
+
+/**
+  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  NanoSeconds;
+  UINT32  Remainder;
+
+  //
+  //          Ticks
+  // Time = --------- x 1,000,000,000
+  //        Frequency
+  //
+  NanoSeconds = MultU64x32 (DivU64x32Remainder (Ticks, PcdGet64 (PcdCpuCoreCrystalClockFrequency), &Remainder), 1000000000u);
+
+  //
+  // Frequency < 0x100000000, so Remainder < 0x100000000, then (Remainder * 1,000,000,000)
+  // will not overflow 64-bit.
+  //
+  NanoSeconds += DivU64x32 (MultU64x32 ((UINT64)Remainder, 1000000000u), PcdGet64 (PcdCpuCoreCrystalClockFrequency));
+
+  return NanoSeconds;
+}
-- 
2.25.1