diff --git a/drivers/iommu/arm-smmu-debug.c b/drivers/iommu/arm-smmu-debug.c
index 9434a8515b60..09ae0818332a 100644
--- a/drivers/iommu/arm-smmu-debug.c
+++ b/drivers/iommu/arm-smmu-debug.c
@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0-only
 /*
- * Copyright (c) 2019-2020, The Linux Foundation. All rights reserved.
+ * Copyright (c) 2019-2021, The Linux Foundation. All rights reserved.
  */
 
 #include <linux/kernel.h>
@@ -38,12 +38,13 @@ u32 arm_smmu_debug_tcu_testbus_select(phys_addr_t phys_addr,
 	int ret = 0;
 
 	if (testbus == CLK_TESTBUS) {
-		offset = ARM_SMMU_TESTBUS_SEL_HLOS1_NS;
 		if (write) {
+			offset = ARM_SMMU_TESTBUS_SEL_HLOS1_NS;
 			writel_relaxed(val, tcu_base + offset);
 			/* Make sure tcu select register is written to */
 			wmb();
 		} else {
+			offset = ARM_SMMU_TCU_TESTBUS_HLOS1_NS;
 			return readl_relaxed(tcu_base + offset);
 		}
 	} else {
diff --git a/drivers/iommu/arm-smmu-debug.h b/drivers/iommu/arm-smmu-debug.h
index c0f39965cc2f..cad03e0091a5 100644
--- a/drivers/iommu/arm-smmu-debug.h
+++ b/drivers/iommu/arm-smmu-debug.h
@@ -1,11 +1,12 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 /*
- * Copyright (c) 2020, The Linux Foundation. All rights reserved.
+ * Copyright (c) 2020-2021, The Linux Foundation. All rights reserved.
  */
 
 #define ARM_SMMU_TESTBUS_SEL			0x25E4
 #define ARM_SMMU_TESTBUS			0x25E8
 #define ARM_SMMU_TESTBUS_SEL_HLOS1_NS		0x8
+#define ARM_SMMU_TCU_TESTBUS_HLOS1_NS		0x28
 #define DEBUG_TESTBUS_SEL_TBU			0x50
 #define DEBUG_TESTBUS_TBU			0x58
 
@@ -21,7 +22,7 @@
 #define TCU_PTW_QUEUE_MASK			GENMASK(7, 0)
 #define TCU_CACHE_TESTBUS_SEL			0x1
 #define TCU_CACHE_LOOKUP_QUEUE_SIZE		32
-#define TCU_CLK_TESTBUS_SEL			0x200
+#define TCU_CLK_TESTBUS_SEL			0x300
 
 
 #define TBU_CLK_GATE_CONTROLLER_TESTBUS_SEL	0x1