xlat v2: Dynamically detect need for CnP bit

ARMv8.2-TTCNP is mandatory from ARMv8.2 onwards, but it can be implemented
in CPUs that don't implement all mandatory 8.2 features (and so have to
claim to be a lower version).

This patch removes usage of the ARM_ARCH_AT_LEAST() macro and uses system
ID registers to detect whether it is needed to set the bit or not.

Change-Id: I7bcbf0c7c937590dfc2ca668cfd9267c50f7d52c
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
diff --git a/include/arch/aarch32/arch.h b/include/arch/aarch32/arch.h
index cbe272c..4af3e90 100644
--- a/include/arch/aarch32/arch.h
+++ b/include/arch/aarch32/arch.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016-2018, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2016-2019, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -94,12 +94,16 @@
 /* CSSELR definitions */
 #define LEVEL_SHIFT		U(1)
 
-/* ID_PFR0 AMU definitions */
+/* ID_MMFR4 definitions */
+#define ID_MMFR4_CNP_SHIFT	U(12)
+#define ID_MMFR4_CNP_LENGTH	U(4)
+#define ID_MMFR4_CNP_MASK	U(0xf)
+
+/* ID_PFR0 definitions */
 #define ID_PFR0_AMU_SHIFT	U(20)
 #define ID_PFR0_AMU_LENGTH	U(4)
 #define ID_PFR0_AMU_MASK	U(0xf)
 
-/* ID_PFR0 DIT definitions */
 #define ID_PFR0_DIT_SHIFT	U(24)
 #define ID_PFR0_DIT_LENGTH	U(4)
 #define ID_PFR0_DIT_MASK	U(0xf)
@@ -475,6 +479,7 @@
 #define DCISW		p15, 0, c7, c6, 2
 #define CTR		p15, 0, c0, c0, 1
 #define CNTFRQ		p15, 0, c14, c0, 0
+#define ID_MMFR4	p15, 0, c0, c2, 6
 #define ID_PFR0		p15, 0, c0, c1, 0
 #define ID_PFR1		p15, 0, c0, c1, 1
 #define MAIR0		p15, 0, c10, c2, 0
diff --git a/include/arch/aarch32/arch_features.h b/include/arch/aarch32/arch_features.h
new file mode 100644
index 0000000..d934102
--- /dev/null
+++ b/include/arch/aarch32/arch_features.h
@@ -0,0 +1,20 @@
+/*
+ * Copyright (c) 2019, Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef ARCH_FEATURES_H
+#define ARCH_FEATURES_H
+
+#include <stdbool.h>
+
+#include <arch_helpers.h>
+
+static inline bool is_armv8_2_ttcnp_present(void)
+{
+	return ((read_id_mmfr4() >> ID_MMFR4_CNP_SHIFT) &
+		ID_MMFR4_CNP_MASK) != 0U;
+}
+
+#endif /* ARCH_FEATURES_H */
diff --git a/include/arch/aarch32/arch_helpers.h b/include/arch/aarch32/arch_helpers.h
index c2773c1..64ddc86 100644
--- a/include/arch/aarch32/arch_helpers.h
+++ b/include/arch/aarch32/arch_helpers.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016-2018, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2016-2019, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -214,6 +214,7 @@
  ******************************************************************************/
 DEFINE_COPROCR_READ_FUNC(mpidr, MPIDR)
 DEFINE_COPROCR_READ_FUNC(midr, MIDR)
+DEFINE_COPROCR_READ_FUNC(id_mmfr4, ID_MMFR4)
 DEFINE_COPROCR_READ_FUNC(id_pfr0, ID_PFR0)
 DEFINE_COPROCR_READ_FUNC(id_pfr1, ID_PFR1)
 DEFINE_COPROCR_READ_FUNC(isr, ISR)