feat(trf): enable trace filter control register access from lower NS EL

Introduced a build flag 'ENABLE_TRF_FOR_NS' to enable trace filter
control registers access in NS-EL2, or NS-EL1 (when NS-EL2 is
implemented but unused).

Change-Id: If3f53b8173a5573424b9a405a4bd8c206ffdeb8c
Signed-off-by: Manish V Badarkhe <Manish.Badarkhe@arm.com>

1 files changed, 35 insertions, 0 deletions

diff --git a/lib/extensions/trf/aarch32/trf.c b/lib/extensions/trf/aarch32/trf.c
new file mode 100644
index 000000000..834092d5a
--- /dev/null
+++ b/lib/extensions/trf/aarch32/trf.c
@@ -0,0 +1,35 @@
+/*
+ * 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)
+{
+	uint32_t features;
+
+	features = read_id_dfr0() >> ID_DFR0_TRACEFILT_SHIFT;
+	return ((features & ID_DFR0_TRACEFILT_MASK) ==
+		ID_DFR0_TRACEFILT_SUPPORTED);
+}
+
+void trf_enable(void)
+{
+	uint32_t val;
+
+	if (trf_supported()) {
+		/*
+		 * Allow access of trace filter control registers from
+		 * non-monitor mode
+		 */
+		val = read_sdcr();
+		val &= ~SDCR_TTRF_BIT;
+		write_sdcr(val);
+	}
+}