refactor(cpufeat): separate the EL2 and EL3 enablement code

Combining the EL2 and EL3 enablement code necessitates that it must be
called at el3_exit, which is the only place with enough context to make
the decision of what needs to be set.
Decouple them to allow them to be called from elsewhere.

Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>
Change-Id: I147764c42771e7d4100699ec8fae98dac0a505c0
diff --git a/lib/extensions/trf/aarch32/trf.c b/lib/extensions/trf/aarch32/trf.c
index 0c63efa..e13b4db 100644
--- a/lib/extensions/trf/aarch32/trf.c
+++ b/lib/extensions/trf/aarch32/trf.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021, Arm Limited. All rights reserved.
+ * Copyright (c) 2021-2023, Arm Limited. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -10,7 +10,7 @@
 #include <arch_helpers.h>
 #include <lib/extensions/trf.h>
 
-void trf_enable(void)
+void trf_init_el3(void)
 {
 	uint32_t val;
 
diff --git a/lib/extensions/trf/aarch64/trf.c b/lib/extensions/trf/aarch64/trf.c
index 941692b..f681b28 100644
--- a/lib/extensions/trf/aarch64/trf.c
+++ b/lib/extensions/trf/aarch64/trf.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021, Arm Limited. All rights reserved.
+ * Copyright (c) 2021-2023, Arm Limited. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -9,9 +9,9 @@
 #include <arch_helpers.h>
 #include <lib/extensions/trf.h>
 
-void trf_enable(void)
+void trf_init_el3(void)
 {
-	uint64_t val;
+	u_register_t val;
 
 	/*
 	 * MDCR_EL3.TTRF = b0
@@ -22,3 +22,15 @@
 	val &= ~MDCR_TTRF_BIT;
 	write_mdcr_el3(val);
 }
+
+void trf_init_el2_unused(void)
+{
+	/*
+	 * MDCR_EL2.TTRF: Set to zero so that access to Trace
+	 *  Filter Control register TRFCR_EL1 at EL1 is not
+	 *  trapped to EL2. This bit is RES0 in versions of
+	 *  the architecture earlier than ARMv8.4.
+	 *
+	 */
+	write_mdcr_el2(read_mdcr_el2() & ~MDCR_EL2_TTRF);
+}