[edk2-devel] [PATCH v1 07/19] MdePkg: Add CSR operation for LoongArch

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

Add CsrRead, CsrWrite and CsrXChg functions for LoongArch, and use them
to operate the CSR register of LoongArch architecture.

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>
Co-authored-by: Bibo Mao <maobibo@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            |  45 +++
 MdePkg/Library/BaseLib/BaseLib.inf          |   2 +
 MdePkg/Library/BaseLib/LoongArch64/AsmCsr.S | 422 ++++++++++++++++++++
 MdePkg/Library/BaseLib/LoongArch64/Csr.c    |  81 ++++
 4 files changed, 550 insertions(+)
 create mode 100644 MdePkg/Library/BaseLib/LoongArch64/AsmCsr.S
 create mode 100644 MdePkg/Library/BaseLib/LoongArch64/Csr.c

diff --git a/MdePkg/Include/Library/BaseLib.h b/MdePkg/Include/Library/BaseLib.h
index 29009adbc9..4e97368ae2 100644
--- a/MdePkg/Include/Library/BaseLib.h
+++ b/MdePkg/Include/Library/BaseLib.h
@@ -351,6 +351,51 @@ AsmReadStableCounter (
   VOID
   );
 
+/**
+  CSR read operation.
+
+  @param[in]  Select   CSR read instruction select values.
+
+  @return     The return value of csrrd instruction, return -1 means no CSR instruction
+              is found.
+**/
+UINTN
+CsrRead (
+  IN UINT16  Select
+  );
+
+/**
+  CSR write operation.
+
+  @param[in]  Select   CSR write instruction select values.
+  @param[in]  Value    The csrwr will write the value.
+
+  @return     The return value of csrwr instruction, that is, store the old value of
+              the register, return -1 means no CSR instruction is found.
+**/
+UINTN
+CsrWrite (
+  IN UINT16  Select,
+  IN UINTN   Value
+  );
+
+/**
+  CSR exchange operation.
+
+  @param[in]  Select   CSR exchange instruction select values.
+  @param[in]  Value    The csrxchg will write the value.
+  @param[in]  Mask     The csrxchg mask value.
+
+  @return     The return value of csrxchg instruction, that is, store the old value of
+              the register, return -1 means no CSR instruction is found.
+**/
+UINTN
+CsrXChg (
+  IN UINT16  Select,
+  IN UINTN   Value,
+  IN UINTN   Mask
+  );
+
 #endif // defined (MDE_CPU_LOONGARCH64)
 
 //
diff --git a/MdePkg/Library/BaseLib/BaseLib.inf b/MdePkg/Library/BaseLib/BaseLib.inf
index 1dad587b0c..7c46306883 100644
--- a/MdePkg/Library/BaseLib/BaseLib.inf
+++ b/MdePkg/Library/BaseLib/BaseLib.inf
@@ -410,7 +410,9 @@ [Sources.RISCV64]
 [Sources.LOONGARCH64]
   Math64.c
   Unaligned.c
+  LoongArch64/Csr.c
   LoongArch64/InternalSwitchStack.c
+  LoongArch64/AsmCsr.S              | GCC
   LoongArch64/GetInterruptState.S   | GCC
   LoongArch64/EnableInterrupts.S    | GCC
   LoongArch64/DisableInterrupts.S   | GCC
diff --git a/MdePkg/Library/BaseLib/LoongArch64/AsmCsr.S b/MdePkg/Library/BaseLib/LoongArch64/AsmCsr.S
new file mode 100644
index 0000000000..3a879411f5
--- /dev/null
+++ b/MdePkg/Library/BaseLib/LoongArch64/AsmCsr.S
@@ -0,0 +1,422 @@
+#------------------------------------------------------------------------------
+#
+# LoongArch ASM CSR operation functions
+#
+# Copyright (c) 2024, Loongson Technology Corporation Limited. All rights reserved.<BR>
+#
+# SPDX-License-Identifier: BSD-2-Clause-Patent
+#
+#------------------------------------------------------------------------------
+
+#include <Register/LoongArch64/Csr.h>
+
+ASM_GLOBAL ASM_PFX (AsmCsrRead)
+ASM_GLOBAL ASM_PFX (AsmCsrWrite)
+ASM_GLOBAL ASM_PFX (AsmCsrXChg)
+
+.macro AsmCsrRd Sel
+  csrrd   $a0, \Sel
+  jirl    $zero, $ra, 0
+.endm
+
+.macro AsmCsrWr Sel
+  csrwr   $a0, \Sel
+  jirl    $zero, $ra, 0
+.endm
+
+.macro AsmCsrXChange Sel
+  csrxchg $a0, $a1, \Sel
+  jirl    $zero, $ra, 0
+.endm
+
+ASM_PFX(AsmCsrRead):
+  blt      $a0, $zero, ReadSelNumErr
+  li.w     $t0, LOONGARCH_CSR_EBASE
+  bltu     $t0, $a0, TlbCsrRd
+
+BasicCsrRd:
+  la.pcrel $t0, BasicCsrRead
+  alsl.d   $t0, $a0, $t0, 3
+  jirl     $zero, $t0, 0
+
+TlbCsrRd:
+  li.w     $t0, LOONGARCH_CSR_TLBIDX
+  bltu     $a0, $t0, ReadSelNumErr
+  li.w     $t0, LOONGARCH_CSR_RVACFG
+  bltu     $t0, $a0, CfgCsrRd
+  la.pcrel $t0, TlbCsrRead
+  addi.w   $t1, $a0, -LOONGARCH_CSR_TLBIDX
+  alsl.d   $t0, $t1, $t0, 3
+  jirl     $zero, $t0, 0
+
+CfgCsrRd:
+  li.w     $t0, LOONGARCH_CSR_CPUNUM
+  bltu     $a0, $t0, ReadSelNumErr
+  li.w     $t0, LOONGARCH_CSR_PRCFG3
+  bltu     $t0, $a0, KcsCsrRd
+  la.pcrel $t0, CfgCsrRead
+  addi.w   $t1, $a0, -LOONGARCH_CSR_CPUNUM
+  alsl.d   $t0, $t1, $t0, 3
+  jirl     $zero, $t0, 0
+
+KcsCsrRd:
+  li.w     $t0, LOONGARCH_CSR_KS0
+  bltu     $a0, $t0, ReadSelNumErr
+  li.w     $t0, LOONGARCH_CSR_KS8
+  bltu     $t0, $a0, StableTimerCsrRd
+  la.pcrel $t0, KcsCsrRead
+  addi.w   $t1, $a0, -LOONGARCH_CSR_KS0
+  alsl.d   $t0, $t1, $t0, 3
+  jirl     $zero, $t0, 0
+
+StableTimerCsrRd:
+  li.w     $t0, LOONGARCH_CSR_TMID
+  bltu     $a0, $t0, ReadSelNumErr
+  li.w     $t0, LOONGARCH_CSR_TINTCLR
+  bltu     $t0, $a0, TlbRefillCsrRd
+  la.pcrel $t0, StableTimerCsrRead
+  addi.w   $t1, $a0, -LOONGARCH_CSR_TMID
+  alsl.d   $t0, $t1, $t0, 3
+  jirl     $zero, $t0, 0
+
+TlbRefillCsrRd:
+  li.w     $t0, LOONGARCH_CSR_TLBREBASE
+  bltu     $a0, $t0, ReadSelNumErr
+  li.w     $t0, LOONGARCH_CSR_TLBREHI
+  bltu     $t0, $a0, DirMapCsrRd
+  la.pcrel $t0, TlbRefillCsrRead
+  addi.w   $t1, $a0, -LOONGARCH_CSR_TLBREBASE
+  alsl.d   $t0, $t1, $t0, 3
+  jirl     $zero, $t0, 0
+
+DirMapCsrRd:
+  li.w     $t0, LOONGARCH_CSR_DMWIN0
+  bltu     $a0, $t0, ReadSelNumErr
+  li.w     $t0, LOONGARCH_CSR_DMWIN3
+  bltu     $t0, $a0, ReadSelNumErr
+  la.pcrel $t0, DirMapCsrRead
+  addi.w   $t1, $a0, -LOONGARCH_CSR_DMWIN0
+  alsl.d   $t0, $t1, $t0, 3
+  jirl     $zero, $t0, 0
+
+ReadSelNumErr:
+  addi.d   $a0, $zero, -1
+  jirl     $zero, $ra, 0
+
+BasicCsrRead:
+  CsrSel = LOONGARCH_CSR_CRMD
+  .rept LOONGARCH_CSR_EBASE - LOONGARCH_CSR_CRMD + 1
+    AsmCsrRd CsrSel
+    CsrSel = CsrSel + 1
+  .endr
+
+TlbCsrRead:
+  CsrSel = LOONGARCH_CSR_TLBIDX
+  .rept LOONGARCH_CSR_RVACFG - LOONGARCH_CSR_TLBIDX + 1
+    AsmCsrRd CsrSel
+    CsrSel = CsrSel + 1
+  .endr
+
+CfgCsrRead:
+  CsrSel = LOONGARCH_CSR_CPUNUM
+  .rept LOONGARCH_CSR_PRCFG3 - LOONGARCH_CSR_CPUNUM + 1
+    AsmCsrRd CsrSel
+    CsrSel = CsrSel + 1
+  .endr
+
+KcsCsrRead:
+  CsrSel = LOONGARCH_CSR_KS0
+  .rept LOONGARCH_CSR_KS8 - LOONGARCH_CSR_KS0 + 1
+    AsmCsrRd CsrSel
+    CsrSel = CsrSel + 1
+  .endr
+
+StableTimerCsrRead:
+  CsrSel = LOONGARCH_CSR_TMID
+  .rept LOONGARCH_CSR_TINTCLR - LOONGARCH_CSR_TMID + 1
+    AsmCsrRd CsrSel
+    CsrSel = CsrSel + 1
+  .endr
+
+TlbRefillCsrRead:
+  CsrSel = LOONGARCH_CSR_TLBREBASE
+  .rept LOONGARCH_CSR_TLBREHI - LOONGARCH_CSR_TLBREBASE + 1
+    AsmCsrRd CsrSel
+    CsrSel = CsrSel + 1
+  .endr
+
+DirMapCsrRead:
+  CsrSel = LOONGARCH_CSR_DMWIN0
+  .rept LOONGARCH_CSR_DMWIN3 - LOONGARCH_CSR_DMWIN0 + 1
+    AsmCsrRd CsrSel
+    CsrSel = CsrSel + 1
+  .endr
+
+ASM_PFX(AsmCsrWrite):
+  blt      $a0, $zero, WriteSelNumErr
+  li.w     $t0, LOONGARCH_CSR_EBASE
+  bltu     $t0, $a0, TlbCsrWr
+
+BasicCsrWr:
+  la.pcrel $t0, BasicCsrWrite
+  alsl.d   $t0, $a0, $t0, 3
+  move     $a0, $a1
+  jirl     $zero, $t0, 0
+
+TlbCsrWr:
+  li.w     $t0, LOONGARCH_CSR_TLBIDX
+  bltu     $a0, $t0, WriteSelNumErr
+  li.w     $t0, LOONGARCH_CSR_RVACFG
+  bltu     $t0, $a0, CfgCsrWr
+  la.pcrel $t0, TlbCsrWrite
+  addi.w   $t1, $a0, -LOONGARCH_CSR_TLBIDX
+  alsl.d   $t0, $t1, $t0, 3
+  move     $a0, $a1
+  jirl     $zero, $t0, 0
+
+CfgCsrWr:
+  li.w     $t0, LOONGARCH_CSR_CPUNUM
+  bltu     $a0, $t0, WriteSelNumErr
+  li.w     $t0, LOONGARCH_CSR_PRCFG3
+  bltu     $t0, $a0, KcsCsrWr
+  la.pcrel $t0, CfgCsrWrite
+  addi.w   $t1, $a0, -LOONGARCH_CSR_CPUNUM
+  alsl.d   $t0, $t1, $t0, 3
+  move     $a0, $a1
+  jirl     $zero, $t0, 0
+
+KcsCsrWr:
+  li.w     $t0, LOONGARCH_CSR_KS0
+  bltu     $a0, $t0, WriteSelNumErr
+  li.w     $t0, LOONGARCH_CSR_KS8
+  bltu     $t0, $a0, StableTimerCsrWr
+  la.pcrel $t0, KcsCsrWrite
+  addi.w   $t1, $a0, -LOONGARCH_CSR_KS0
+  alsl.d   $t0, $t1, $t0, 3
+  move     $a0, $a1
+  jirl     $zero, $t0, 0
+
+StableTimerCsrWr:
+  li.w     $t0, LOONGARCH_CSR_TMID
+  bltu     $a0, $t0, WriteSelNumErr
+  li.w     $t0, LOONGARCH_CSR_TINTCLR
+  bltu     $t0, $a0, TlbRefillCsrWr
+  la.pcrel $t0, StableTimerCsrWrite
+  addi.w   $t1, $a0, -LOONGARCH_CSR_TMID
+  alsl.d   $t0, $t1, $t0, 3
+  move     $a0, $a1
+  jirl     $zero, $t0, 0
+
+TlbRefillCsrWr:
+  li.w     $t0, LOONGARCH_CSR_TLBREBASE
+  bltu     $a0, $t0, WriteSelNumErr
+  li.w     $t0, LOONGARCH_CSR_TLBREHI
+  bltu     $t0, $a0, DirMapCsrWr
+  la.pcrel $t0, TlbRefillCsrWrite
+  addi.w   $t1, $a0, -LOONGARCH_CSR_TLBREBASE
+  alsl.d   $t0, $t1, $t0, 3
+  move     $a0, $a1
+  jirl     $zero, $t0, 0
+
+DirMapCsrWr:
+  li.w     $t0, LOONGARCH_CSR_DMWIN0
+  bltu     $a0, $t0, WriteSelNumErr
+  li.w     $t0, LOONGARCH_CSR_DMWIN3
+  bltu     $t0, $a0, WriteSelNumErr
+  la.pcrel $t0, DirMapCsrWrite
+  addi.w   $t1, $a0, -LOONGARCH_CSR_DMWIN0
+  alsl.d   $t0, $t1, $t0, 3
+  move     $a0, $a1
+  jirl     $zero, $t0, 0
+
+WriteSelNumErr:
+  addi.d   $a0, $zero, -1
+  jirl     $zero, $ra, 0
+
+BasicCsrWrite:
+  CsrSel = LOONGARCH_CSR_CRMD
+  .rept LOONGARCH_CSR_EBASE - LOONGARCH_CSR_CRMD + 1
+    AsmCsrWr CsrSel
+    CsrSel = CsrSel + 1
+  .endr
+
+TlbCsrWrite:
+  CsrSel = LOONGARCH_CSR_TLBIDX
+  .rept LOONGARCH_CSR_RVACFG - LOONGARCH_CSR_TLBIDX + 1
+    AsmCsrWr CsrSel
+    CsrSel = CsrSel + 1
+  .endr
+
+CfgCsrWrite:
+  CsrSel = LOONGARCH_CSR_CPUNUM
+  .rept LOONGARCH_CSR_PRCFG3 - LOONGARCH_CSR_CPUNUM + 1
+    AsmCsrWr CsrSel
+    CsrSel = CsrSel + 1
+  .endr
+
+KcsCsrWrite:
+  CsrSel = LOONGARCH_CSR_KS0
+  .rept LOONGARCH_CSR_KS8 - LOONGARCH_CSR_KS0 + 1
+    AsmCsrWr CsrSel
+    CsrSel = CsrSel + 1
+  .endr
+
+StableTimerCsrWrite:
+  CsrSel = LOONGARCH_CSR_TMID
+  .rept LOONGARCH_CSR_TINTCLR - LOONGARCH_CSR_TMID + 1
+    AsmCsrWr CsrSel
+    CsrSel = CsrSel + 1
+  .endr
+
+TlbRefillCsrWrite:
+  CsrSel = LOONGARCH_CSR_TLBREBASE
+  .rept LOONGARCH_CSR_TLBREHI - LOONGARCH_CSR_TLBREBASE + 1
+    AsmCsrWr CsrSel
+    CsrSel = CsrSel + 1
+  .endr
+
+DirMapCsrWrite:
+  CsrSel = LOONGARCH_CSR_DMWIN0
+  .rept LOONGARCH_CSR_DMWIN3 - LOONGARCH_CSR_DMWIN0 + 1
+    AsmCsrWr CsrSel
+    CsrSel = CsrSel + 1
+  .endr
+
+
+ASM_PFX(AsmCsrXChg):
+  blt      $a0, $zero, XchgSelNumErr
+  li.w     $t0, LOONGARCH_CSR_EBASE
+  bltu     $t0, $a0, TlbCsrXchg
+
+BasicCsrXchg:
+  la.pcrel $t0, BasicCsrXchange
+  alsl.d   $t0, $a0, $t0, 3
+  move     $a0, $a1
+  move     $a1, $a2
+  jirl     $zero, $t0, 0
+
+TlbCsrXchg:
+  li.w     $t0, LOONGARCH_CSR_TLBIDX
+  bltu     $a0, $t0, XchgSelNumErr
+  li.w     $t0, LOONGARCH_CSR_RVACFG
+  bltu     $t0, $a0, CfgCsrXchg
+  la.pcrel $t0, TlbCsrXchange
+  addi.w   $t1, $a0, -LOONGARCH_CSR_TLBIDX
+  alsl.d   $t0, $t1, $t0, 3
+  move     $a0, $a1
+  move     $a1, $a2
+  jirl     $zero, $t0, 0
+
+CfgCsrXchg:
+  li.w     $t0, LOONGARCH_CSR_CPUNUM
+  bltu     $a0, $t0, XchgSelNumErr
+  li.w     $t0, LOONGARCH_CSR_PRCFG3
+  bltu     $t0, $a0, KcsCsrXchg
+  la.pcrel $t0, CfgCsrXchange
+  addi.w   $t1, $a0, -LOONGARCH_CSR_CPUNUM
+  alsl.d   $t0, $t1, $t0, 3
+  move     $a0, $a1
+  move     $a1, $a2
+  jirl     $zero, $t0, 0
+
+KcsCsrXchg:
+  li.w     $t0, LOONGARCH_CSR_KS0
+  bltu     $a0, $t0, XchgSelNumErr
+  li.w     $t0, LOONGARCH_CSR_KS8
+  bltu     $t0, $a0, StableTimerCsrXchg
+  la.pcrel $t0, KcsCsrXchange
+  addi.w   $t1, $a0, -LOONGARCH_CSR_KS0
+  alsl.d   $t0, $t1, $t0, 3
+  move     $a0, $a1
+  move     $a1, $a2
+  jirl     $zero, $t0, 0
+
+StableTimerCsrXchg:
+  li.w     $t0, LOONGARCH_CSR_TMID
+  bltu     $a0, $t0, XchgSelNumErr
+  li.w     $t0, LOONGARCH_CSR_TINTCLR
+  bltu     $t0, $a0, TlbRefillCsrXchg
+  la.pcrel $t0, StableTimerCsrXchange
+  addi.w   $t1, $a0, -LOONGARCH_CSR_TMID
+  alsl.d   $t0, $t1, $t0, 3
+  move     $a0, $a1
+  move     $a1, $a2
+  jirl     $zero, $t0, 0
+
+TlbRefillCsrXchg:
+  li.w     $t0, LOONGARCH_CSR_TLBREBASE
+  bltu     $a0, $t0, XchgSelNumErr
+  li.w     $t0, LOONGARCH_CSR_TLBREHI
+  bltu     $t0, $a0, DirMapCsrXchg
+  la.pcrel $t0, TlbRefillCsrXchange
+  addi.w   $t1, $a0, -LOONGARCH_CSR_TLBREBASE
+  alsl.d   $t0, $t1, $t0, 3
+  move     $a0, $a1
+  move     $a1, $a2
+  jirl     $zero, $t0, 0
+
+DirMapCsrXchg:
+  li.w     $t0, LOONGARCH_CSR_DMWIN0
+  bltu     $a0, $t0, XchgSelNumErr
+  li.w     $t0, LOONGARCH_CSR_DMWIN3
+  bltu     $t0, $a0, XchgSelNumErr
+  la.pcrel $t0, DirMapCsrXchange
+  addi.w   $t1, $a0, -LOONGARCH_CSR_DMWIN0
+  alsl.d   $t0, $t1, $t0, 3
+  move     $a0, $a1
+  move     $a1, $a2
+  jirl     $zero, $t0, 0
+
+XchgSelNumErr:
+  addi.d   $a0, $zero, -1
+  jirl     $zero, $ra, 0
+
+BasicCsrXchange:
+  CsrSel = LOONGARCH_CSR_CRMD
+  .rept LOONGARCH_CSR_EBASE - LOONGARCH_CSR_CRMD + 1
+    AsmCsrXChange CsrSel
+    CsrSel = CsrSel + 1
+  .endr
+
+TlbCsrXchange:
+  CsrSel = LOONGARCH_CSR_TLBIDX
+  .rept LOONGARCH_CSR_RVACFG - LOONGARCH_CSR_TLBIDX + 1
+    AsmCsrXChange CsrSel
+    CsrSel = CsrSel + 1
+  .endr
+
+CfgCsrXchange:
+  CsrSel = LOONGARCH_CSR_CPUNUM
+  .rept LOONGARCH_CSR_PRCFG3 - LOONGARCH_CSR_CPUNUM + 1
+    AsmCsrXChange CsrSel
+    CsrSel = CsrSel + 1
+  .endr
+
+KcsCsrXchange:
+  CsrSel = LOONGARCH_CSR_KS0
+  .rept LOONGARCH_CSR_KS8 - LOONGARCH_CSR_KS0 + 1
+    AsmCsrXChange CsrSel
+    CsrSel = CsrSel + 1
+  .endr
+
+StableTimerCsrXchange:
+  CsrSel = LOONGARCH_CSR_TMID
+  .rept LOONGARCH_CSR_TINTCLR - LOONGARCH_CSR_TMID + 1
+    AsmCsrXChange CsrSel
+    CsrSel = CsrSel + 1
+  .endr
+
+TlbRefillCsrXchange:
+  CsrSel = LOONGARCH_CSR_TLBREBASE
+  .rept LOONGARCH_CSR_TLBREHI - LOONGARCH_CSR_TLBREBASE + 1
+    AsmCsrXChange CsrSel
+    CsrSel = CsrSel + 1
+  .endr
+
+DirMapCsrXchange:
+  CsrSel = LOONGARCH_CSR_DMWIN0
+  .rept LOONGARCH_CSR_DMWIN3 - LOONGARCH_CSR_DMWIN0 + 1
+    AsmCsrXChange CsrSel
+    CsrSel = CsrSel + 1
+  .endr
+.end
diff --git a/MdePkg/Library/BaseLib/LoongArch64/Csr.c b/MdePkg/Library/BaseLib/LoongArch64/Csr.c
new file mode 100644
index 0000000000..f2ec80b38d
--- /dev/null
+++ b/MdePkg/Library/BaseLib/LoongArch64/Csr.c
@@ -0,0 +1,81 @@
+/** @file
+  LoongArch CSR operation functions.
+
+  Copyright (c) 2024, Loongson Technology Corporation Limited. All rights reserved.<BR>
+
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+**/
+
+UINTN
+AsmCsrRead (
+  IN UINT16  Select
+  );
+
+UINTN
+AsmCsrWrite (
+  IN UINT16  Select,
+  IN UINTN   Value
+  );
+
+UINTN
+AsmCsrXChg (
+  IN UINT16  Select,
+  IN UINTN   Value,
+  IN UINTN   Mask
+  );
+
+/**
+  CSR read operation.
+
+  @param[in]  Select   CSR read instruction select values.
+
+  @return     The return value of csrrd instruction, return -1 means Select is out of support.
+**/
+UINTN
+EFIAPI
+CsrRead (
+  IN UINT16  Select
+  )
+{
+  return AsmCsrRead (Select);
+}
+
+/**
+  CSR write operation.
+
+  @param[in]       Select  CSR write instruction select values.
+  @param[in, out]  Value   The csrwr will write the value.
+
+  @return     The return value of csrwr instruction, that is, store the old value of
+              the register, return -1 means Select is out of support.
+**/
+UINTN
+EFIAPI
+CsrWrite (
+  IN     UINT16  Select,
+  IN OUT UINTN   Value
+  )
+{
+  return AsmCsrWrite (Select, Value);
+}
+
+/**
+  CSR exchange operation.
+
+  @param[in]       Select   CSR exchange instruction select values.
+  @param[in, out]  Value    The csrxchg will write the value.
+  @param[in]       Mask     The csrxchg mask value.
+
+  @return     The return value of csrxchg instruction, that is, store the old value of
+              the register, return -1 means Select is out of support.
+**/
+UINTN
+EFIAPI
+CsrXChg (
+  IN     UINT16  Select,
+  IN OUT UINTN   Value,
+  IN     UINTN   Mask
+  )
+{
+  return AsmCsrXChg (Select, Value, Mask);
+}
-- 
2.27.0



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