1 files changed, 36 insertions, 0 deletions
diff --git a/lib/extensions/trf/aarch64/trf.c b/lib/extensions/trf/aarch64/trf.c
new file mode 100644
index 0000000..1da5dce
--- /dev/null
+++ b/lib/extensions/trf/aarch64/trf.c
@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2021, Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <stdbool.h>
+
+#include <arch.h>
+#include <arch_helpers.h>
+#include <lib/extensions/trf.h>
+
+static bool trf_supported(void)
+{
+	uint64_t features;
+
+	features = read_id_aa64dfr0_el1() >> ID_AA64DFR0_TRACEFILT_SHIFT;
+	return ((features & ID_AA64DFR0_TRACEFILT_MASK) ==
+		ID_AA64DFR0_TRACEFILT_SUPPORTED);
+}
+
+void trf_enable(void)
+{
+	uint64_t val;
+
+	if (trf_supported()) {
+		/*
+		 * MDCR_EL3.TTRF = b0
+		 * Allow access of trace filter control registers from NS-EL2
+		 * and NS-EL1 when NS-EL2 is implemented but not used
+		 */
+		val = read_mdcr_el3();
+		val &= ~MDCR_TTRF_BIT;
+		write_mdcr_el3(val);
+	}
+}