From 08431081a3623bd6c44de5c859ef42c579de63d1 Mon Sep 17 00:00:00 2001
From: Sami Mujawar <sami.mujawar@arm.com>
Date: Fri, 22 Sep 2023 15:35:15 +0100
Subject: ArmPkg/ArmLib: Add ArmHasTrbe () helper function

Create a helper function to query whether ID_AA64MFR1_EL1 indicates
presence of the Trace Buffer Extension (TRBE). This feature is only
visible in AARCH64 state.

Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Leif Lindholm <quic_llindhol@quicinc.com>
Cc: Pierre Gondois <pierre.gondois@arm.com>
Signed-off-by: Sami Mujawar <sami.mujawar@arm.com>
Reviewed-by: Leif Lindholm <quic_llindhol@quicinc.com>
Reviewed-by: Pierre Gondois <pierre.gondois@arm.com>
---
 ArmPkg/Include/Chipset/AArch64.h           |  3 +++
 ArmPkg/Include/Library/ArmLib.h            | 13 +++++++++++++
 ArmPkg/Library/ArmLib/AArch64/AArch64Lib.c | 15 +++++++++++++++
 3 files changed, 31 insertions(+)

diff --git a/ArmPkg/Include/Chipset/AArch64.h b/ArmPkg/Include/Chipset/AArch64.h
index 2e87917049..d8711ad711 100644
--- a/ArmPkg/Include/Chipset/AArch64.h
+++ b/ArmPkg/Include/Chipset/AArch64.h
@@ -31,6 +31,9 @@
 #define AARCH64_PFR0_FP   (0xF << 16)
 #define AARCH64_PFR0_GIC  (0xF << 24)
 
+// ID_AA64DFR0 - AArch64 Debug Feature Register 0 definitions
+#define AARCH64_DFR0_TRBE  (0xFULL << 44)
+
 // SCR - Secure Configuration Register definitions
 #define SCR_NS   (1 << 0)
 #define SCR_IRQ  (1 << 1)
diff --git a/ArmPkg/Include/Library/ArmLib.h b/ArmPkg/Include/Library/ArmLib.h
index 0169dbc109..c2d738c06e 100644
--- a/ArmPkg/Include/Library/ArmLib.h
+++ b/ArmPkg/Include/Library/ArmLib.h
@@ -780,6 +780,19 @@ EFIAPI
 ArmHasVhe (
   VOID
   );
+
+/**
+  Checks whether the CPU implements the Trace Buffer Extension.
+
+  @retval TRUE  FEAT_TRBE is implemented.
+  @retval FALSE FEAT_TRBE is not mplemented.
+**/
+BOOLEAN
+EFIAPI
+ArmHasTrbe (
+  VOID
+  );
+
 #endif // MDE_CPU_AARCH64
 
 #ifdef MDE_CPU_ARM
diff --git a/ArmPkg/Library/ArmLib/AArch64/AArch64Lib.c b/ArmPkg/Library/ArmLib/AArch64/AArch64Lib.c
index da5755106e..3a46f360ef 100644
--- a/ArmPkg/Library/ArmLib/AArch64/AArch64Lib.c
+++ b/ArmPkg/Library/ArmLib/AArch64/AArch64Lib.c
@@ -119,3 +119,18 @@ ArmHasVhe (
 {
   return ((ArmReadIdAA64Mmfr1 () & AARCH64_MMFR1_VH) != 0);
 }
+
+/**
+  Checks whether the CPU implements the Trace Buffer Extension.
+
+  @retval TRUE  FEAT_TRBE is implemented.
+  @retval FALSE FEAT_TRBE is not mplemented.
+**/
+BOOLEAN
+EFIAPI
+ArmHasTrbe (
+  VOID
+  )
+{
+  return ((ArmReadIdAA64Dfr0 () & AARCH64_DFR0_TRBE) != 0);
+}
-- 
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