[PATCH 2/2] ArmPlatformPkg: Timer access for non-secure EL1/0

[evan.lloyd@arm.com]

From: Sami Mujawar <sami.mujawar@arm.com>

According to Section 2.3.6 of the "UEFI Specification 2.6 Errata A";
the primary CPU must be configured such that 'Timer access must be
provided to non-secure EL1 and EL0 by setting bits EL1PCTEN and
EL1PCEN in register CNTHCTL_EL2.'

This commit adds this missing set-up to the PrePi and PrePeiCore
modules.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Sami Mujawar <sami.mujawar@arm.com>
Signed-off-by: Evan Lloyd <evan.lloyd@arm.com>
---
 ArmPlatformPkg/PrePi/AArch64/ArchPrePi.c   | 9 ++++++++-
 ArmPlatformPkg/PrePeiCore/AArch64/Helper.S | 9 ++++++++-
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/ArmPlatformPkg/PrePi/AArch64/ArchPrePi.c b/ArmPlatformPkg/PrePi/AArch64/ArchPrePi.c
index 217986107e44185c2c6e11ca8a417fad659cde2f..4da590805aaae4016952c0e5e9ce90c1897e37c4 100644
--- a/ArmPlatformPkg/PrePi/AArch64/ArchPrePi.c
+++ b/ArmPlatformPkg/PrePi/AArch64/ArchPrePi.c
@@ -1,6 +1,6 @@
 /** @file
 *
-*  Copyright (c) 2011-2013, ARM Limited. All rights reserved.
+*  Copyright (c) 2011-2017, ARM Limited. All rights reserved.
 *
 *  This program and the accompanying materials
 *  are licensed and made available under the terms and conditions of the BSD License
@@ -29,5 +29,12 @@ ArchInitialize (
   if (ArmReadCurrentEL () == AARCH64_EL2) {
     // Trap General Exceptions. All exceptions that would be routed to EL1 are routed to EL2
     ArmWriteHcr (ARM_HCR_TGE);
+
+    /* Enable Timer access for non-secure EL1 and EL0
+       The cnthctl_el2 register bits are architecturally
+       UNKNOWN on reset.
+       Disable event stream as it is not in use at this stage
+    */
+    ArmWriteCntHctl (CNTHCTL_EL2_EL1PCTEN | CNTHCTL_EL2_EL1PCEN);
   }
 }
diff --git a/ArmPlatformPkg/PrePeiCore/AArch64/Helper.S b/ArmPlatformPkg/PrePeiCore/AArch64/Helper.S
index 5f35484b1259f8b85c370de2cde945db2b799c13..b4f35b7ff5d389ecf61c025f85bb6cf8fcce793d 100644
--- a/ArmPlatformPkg/PrePeiCore/AArch64/Helper.S
+++ b/ArmPlatformPkg/PrePeiCore/AArch64/Helper.S
@@ -1,5 +1,5 @@
 #========================================================================================
-#  Copyright (c) 2011-2013, ARM Limited. All rights reserved.
+#  Copyright (c) 2011-2017, ARM Limited. All rights reserved.
 #
 #  This program and the accompanying materials
 #  are licensed and made available under the terms and conditions of the BSD License
@@ -36,6 +36,13 @@ ASM_FUNC(SetupExceptionLevel2)
 
    msr     cptr_el2, xzr          // Disable copro traps to EL2
 
+   // Enable Timer access for non-secure EL1 and EL0
+   // The cnthctl_el2 register bits are architecturally
+   // UNKNOWN on reset.
+   // Disable event stream as it is not in use at this stage
+   mov     x0, #(CNTHCTL_EL2_EL1PCTEN | CNTHCTL_EL2_EL1PCEN)
+   msr     cnthctl_el2, x0
+
    ret
 
 ASM_FUNCTION_REMOVE_IF_UNREFERENCED
-- 
Guid("CE165669-3EF3-493F-B85D-6190EE5B9759")