MdePkg: Add read stable counter operation for LoongArch

Add LoongArch gets stable counter ASM function.

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=4584

Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Zhiguang Liu <zhiguang.liu@intel.com>
Signed-off-by: Chao Li <lichao@loongson.cn>
Acked-by: Michael D Kinney <michael.d.kinney@intel.com>
Reviewed-by: Liming Gao <gaoliming@byosoft.com.cn>

MdePkg/Include/Library/BaseLib.h

@@ -339,6 +339,18 @@ AsmCpucfg (
   OUT UINT32  *Data
   );
 
+/**
+  Gets the timer count value.
+
+  @param[] VOID
+  @retval  timer count value.
+
+**/
+UINTN
+AsmReadStableCounter (
+  VOID
+  );
+
 #endif // defined (MDE_CPU_LOONGARCH64)
 
 //

MdePkg/Library/BaseLib/BaseLib.inf

@@ -422,6 +422,7 @@
   LoongArch64/SwitchStack.S         | GCC
   LoongArch64/ExceptionBase.S       | GCC
   LoongArch64/Cpucfg.S              | GCC
+  LoongArch64/ReadStableCounter.S   | GCC
 
 [Packages]
   MdePkg/MdePkg.dec

MdePkg/Library/BaseLib/LoongArch64/ReadStableCounter.S

@@ -0,0 +1,24 @@
+#------------------------------------------------------------------------------
+#
+# LoongArch Read Stable Counter
+#
+# Copyright (c) 2024, Loongson Technology Corporation Limited. All rights reserved.<BR>
+#
+# SPDX-License-Identifier: BSD-2-Clause-Patent
+#
+#------------------------------------------------------------------------------
+
+ASM_GLOBAL ASM_PFX(AsmReadStableCounter)
+
+#/**
+#  Gets the timer count value.
+#
+#  @param[] VOID
+#  @retval  timer count value.
+#
+#**/
+
+ASM_PFX(AsmReadStableCounter):
+  rdtime.d   $a0, $zero
+  jirl       $zero, $ra, 0
+  .end