diff --git a/drivers/arm/gic/gic_v3.c b/drivers/arm/gic/gic_v3.c
index 3e802fd..5486817 100644
--- a/drivers/arm/gic/gic_v3.c
+++ b/drivers/arm/gic/gic_v3.c
@@ -8,7 +8,7 @@
 #include <debug.h>
 #include <gic_v3.h>
 
-uintptr_t gicv3_get_rdist(uintptr_t gicr_base, uint64_t mpidr)
+uintptr_t gicv3_get_rdist(uintptr_t gicr_base, u_register_t mpidr)
 {
 	uint32_t  cpu_aff, gicr_aff;
 	uint64_t  gicr_typer;
diff --git a/plat/mediatek/common/custom/oem_svc.c b/plat/mediatek/common/custom/oem_svc.c
index 49e7571..c396e2d 100644
--- a/plat/mediatek/common/custom/oem_svc.c
+++ b/plat/mediatek/common/custom/oem_svc.c
@@ -32,14 +32,14 @@
 /*******************************************************************************
  * OEM top level handler for servicing SMCs.
  ******************************************************************************/
-uint64_t oem_smc_handler(uint32_t smc_fid,
-			uint64_t x1,
-			uint64_t x2,
-			uint64_t x3,
-			uint64_t x4,
+uintptr_t oem_smc_handler(uint32_t smc_fid,
+			u_register_t x1,
+			u_register_t x2,
+			u_register_t x3,
+			u_register_t x4,
 			void *cookie,
 			void *handle,
-			uint64_t flags)
+			u_register_t flags)
 {
 	WARN("Unimplemented OEM Call: 0x%x\n", smc_fid);
 	SMC_RET1(handle, SMC_UNK);
@@ -49,14 +49,14 @@
  * Top-level OEM Service SMC handler. This handler will in turn dispatch
  * calls to related SMC handler
  */
-uint64_t oem_svc_smc_handler(uint32_t smc_fid,
-			 uint64_t x1,
-			 uint64_t x2,
-			 uint64_t x3,
-			 uint64_t x4,
+uintptr_t oem_svc_smc_handler(uint32_t smc_fid,
+			 u_register_t x1,
+			 u_register_t x2,
+			 u_register_t x3,
+			 u_register_t x4,
 			 void *cookie,
 			 void *handle,
-			 uint64_t flags)
+			 u_register_t flags)
 {
 	/*
 	 * Dispatch OEM calls to OEM Common handler and return its return value
diff --git a/plat/mediatek/common/mtk_plat_common.c b/plat/mediatek/common/mtk_plat_common.c
index 6a13192..a15131d 100644
--- a/plat/mediatek/common/mtk_plat_common.c
+++ b/plat/mediatek/common/mtk_plat_common.c
@@ -19,10 +19,10 @@
 struct atf_arg_t gteearg;
 
 void clean_top_32b_of_param(uint32_t smc_fid,
-				uint64_t *px1,
-				uint64_t *px2,
-				uint64_t *px3,
-				uint64_t *px4)
+				u_register_t *px1,
+				u_register_t *px2,
+				u_register_t *px3,
+				u_register_t *px4)
 {
 	/* if parameters from SMC32. Clean top 32 bits */
 	if (0 == (smc_fid & SMC_AARCH64_BIT)) {
diff --git a/plat/mediatek/common/mtk_plat_common.h b/plat/mediatek/common/mtk_plat_common.h
index 7513bc7..501c339 100644
--- a/plat/mediatek/common/mtk_plat_common.h
+++ b/plat/mediatek/common/mtk_plat_common.h
@@ -48,10 +48,10 @@
 /* Declarations for mtk_plat_common.c */
 uint32_t plat_get_spsr_for_bl32_entry(void);
 uint32_t plat_get_spsr_for_bl33_entry(void);
-void clean_top_32b_of_param(uint32_t smc_fid, uint64_t *x1,
-				uint64_t *x2,
-				uint64_t *x3,
-				uint64_t *x4);
+void clean_top_32b_of_param(uint32_t smc_fid, u_register_t *x1,
+				u_register_t *x2,
+				u_register_t *x3,
+				u_register_t *x4);
 void bl31_prepare_kernel_entry(uint64_t k32_64);
 void enable_ns_access_to_cpuectlr(void);
 void boot_to_kernel(uint64_t x1, uint64_t x2, uint64_t x3, uint64_t x4);
diff --git a/plat/mediatek/common/mtk_sip_svc.c b/plat/mediatek/common/mtk_sip_svc.c
index 869a959..ea8cea0 100644
--- a/plat/mediatek/common/mtk_sip_svc.c
+++ b/plat/mediatek/common/mtk_sip_svc.c
@@ -19,14 +19,14 @@
 		0x8f, 0x95, 0x05, 0x00, 0x0f, 0x3d);
 
 #pragma weak mediatek_plat_sip_handler
-uint64_t mediatek_plat_sip_handler(uint32_t smc_fid,
-				uint64_t x1,
-				uint64_t x2,
-				uint64_t x3,
-				uint64_t x4,
+uintptr_t mediatek_plat_sip_handler(uint32_t smc_fid,
+				u_register_t x1,
+				u_register_t x2,
+				u_register_t x3,
+				u_register_t x4,
 				void *cookie,
 				void *handle,
-				uint64_t flags)
+				u_register_t flags)
 {
 	ERROR("%s: unhandled SMC (0x%x)\n", __func__, smc_fid);
 	SMC_RET1(handle, SMC_UNK);
@@ -34,14 +34,14 @@
 
 /*
  * This function handles Mediatek defined SiP Calls */
-uint64_t mediatek_sip_handler(uint32_t smc_fid,
-			uint64_t x1,
-			uint64_t x2,
-			uint64_t x3,
-			uint64_t x4,
+uintptr_t mediatek_sip_handler(uint32_t smc_fid,
+			u_register_t x1,
+			u_register_t x2,
+			u_register_t x3,
+			u_register_t x4,
 			void *cookie,
 			void *handle,
-			uint64_t flags)
+			u_register_t flags)
 {
 	uint32_t ns;
 
@@ -85,14 +85,14 @@
 /*
  * This function is responsible for handling all SiP calls from the NS world
  */
-uint64_t sip_smc_handler(uint32_t smc_fid,
-			 uint64_t x1,
-			 uint64_t x2,
-			 uint64_t x3,
-			 uint64_t x4,
+uintptr_t sip_smc_handler(uint32_t smc_fid,
+			 u_register_t x1,
+			 u_register_t x2,
+			 u_register_t x3,
+			 u_register_t x4,
 			 void *cookie,
 			 void *handle,
-			 uint64_t flags)
+			 u_register_t flags)
 {
 	switch (smc_fid) {
 	case SIP_SVC_CALL_COUNT:
diff --git a/plat/nvidia/tegra/common/tegra_sip_calls.c b/plat/nvidia/tegra/common/tegra_sip_calls.c
index d96ce7a..a818453 100644
--- a/plat/nvidia/tegra/common/tegra_sip_calls.c
+++ b/plat/nvidia/tegra/common/tegra_sip_calls.c
@@ -49,14 +49,14 @@
 /*******************************************************************************
  * This function is responsible for handling all SiP calls
  ******************************************************************************/
-uint64_t tegra_sip_handler(uint32_t smc_fid,
-			   uint64_t x1,
-			   uint64_t x2,
-			   uint64_t x3,
-			   uint64_t x4,
-			   void *cookie,
-			   void *handle,
-			   uint64_t flags)
+uintptr_t tegra_sip_handler(uint32_t smc_fid,
+			    u_register_t x1,
+			    u_register_t x2,
+			    u_register_t x3,
+			    u_register_t x4,
+			    void *cookie,
+			    void *handle,
+			    u_register_t flags)
 {
 	uint32_t regval;
 	int err;
diff --git a/plat/rockchip/common/rockchip_sip_svc.c b/plat/rockchip/common/rockchip_sip_svc.c
index eca4f99..2480599 100644
--- a/plat/rockchip/common/rockchip_sip_svc.c
+++ b/plat/rockchip/common/rockchip_sip_svc.c
@@ -18,14 +18,14 @@
 		0x8f, 0x88, 0xee, 0x74, 0x7b, 0x72);
 
 #pragma weak rockchip_plat_sip_handler
-uint64_t rockchip_plat_sip_handler(uint32_t smc_fid,
-				   uint64_t x1,
-				   uint64_t x2,
-				   uint64_t x3,
-				   uint64_t x4,
-				   void *cookie,
-				   void *handle,
-				   uint64_t flags)
+uintptr_t rockchip_plat_sip_handler(uint32_t smc_fid,
+				    u_register_t x1,
+				    u_register_t x2,
+				    u_register_t x3,
+				    u_register_t x4,
+				    void *cookie,
+				    void *handle,
+				    u_register_t flags)
 {
 	ERROR("%s: unhandled SMC (0x%x)\n", __func__, smc_fid);
 	SMC_RET1(handle, SMC_UNK);
@@ -34,14 +34,14 @@
 /*
  * This function is responsible for handling all SiP calls from the NS world
  */
-uint64_t sip_smc_handler(uint32_t smc_fid,
-			 uint64_t x1,
-			 uint64_t x2,
-			 uint64_t x3,
-			 uint64_t x4,
-			 void *cookie,
-			 void *handle,
-			 uint64_t flags)
+uintptr_t sip_smc_handler(uint32_t smc_fid,
+			  u_register_t x1,
+			  u_register_t x2,
+			  u_register_t x3,
+			  u_register_t x4,
+			  void *cookie,
+			  void *handle,
+			  u_register_t flags)
 {
 	uint32_t ns;
 
diff --git a/plat/rockchip/rk3368/plat_sip_calls.c b/plat/rockchip/rk3368/plat_sip_calls.c
index 03fee88..c0f43db 100644
--- a/plat/rockchip/rk3368/plat_sip_calls.c
+++ b/plat/rockchip/rk3368/plat_sip_calls.c
@@ -10,14 +10,14 @@
 #include <rockchip_sip_svc.h>
 #include <runtime_svc.h>
 
-uint64_t rockchip_plat_sip_handler(uint32_t smc_fid,
-				   uint64_t x1,
-				   uint64_t x2,
-				   uint64_t x3,
-				   uint64_t x4,
+uintptr_t rockchip_plat_sip_handler(uint32_t smc_fid,
+				   u_register_t x1,
+				   u_register_t x2,
+				   u_register_t x3,
+				   u_register_t x4,
 				   void *cookie,
 				   void *handle,
-				   uint64_t flags)
+				   u_register_t flags)
 {
 	ERROR("%s: unhandled SMC (0x%x)\n", __func__, smc_fid);
 	SMC_RET1(handle, SMC_UNK);
diff --git a/plat/rockchip/rk3399/plat_sip_calls.c b/plat/rockchip/rk3399/plat_sip_calls.c
index 2fbda67..ae74c9c 100644
--- a/plat/rockchip/rk3399/plat_sip_calls.c
+++ b/plat/rockchip/rk3399/plat_sip_calls.c
@@ -47,14 +47,14 @@
 	return 0;
 }
 
-uint64_t rockchip_plat_sip_handler(uint32_t smc_fid,
-				   uint64_t x1,
-				   uint64_t x2,
-				   uint64_t x3,
-				   uint64_t x4,
-				   void *cookie,
-				   void *handle,
-				   uint64_t flags)
+uintptr_t rockchip_plat_sip_handler(uint32_t smc_fid,
+				    u_register_t x1,
+				    u_register_t x2,
+				    u_register_t x3,
+				    u_register_t x4,
+				    void *cookie,
+				    void *handle,
+				    u_register_t flags)
 {
 	uint64_t x5, x6;
 
diff --git a/plat/xilinx/zynqmp/sip_svc_setup.c b/plat/xilinx/zynqmp/sip_svc_setup.c
index 8b44eaa..c7996ce 100644
--- a/plat/xilinx/zynqmp/sip_svc_setup.c
+++ b/plat/xilinx/zynqmp/sip_svc_setup.c
@@ -52,14 +52,14 @@
  * Handler for all SiP SMC calls. Handles standard SIP requests
  * and calls PM SMC handler if the call is for a PM-API function.
  */
-uint64_t sip_svc_smc_handler(uint32_t smc_fid,
-			     uint64_t x1,
-			     uint64_t x2,
-			     uint64_t x3,
-			     uint64_t x4,
-			     void *cookie,
-			     void *handle,
-			     uint64_t flags)
+uintptr_t sip_svc_smc_handler(uint32_t smc_fid,
+			      u_register_t x1,
+			      u_register_t x2,
+			      u_register_t x3,
+			      u_register_t x4,
+			      void *cookie,
+			      void *handle,
+			      u_register_t flags)
 {
 	/* Let PM SMC handler deal with PM-related requests */
 	if (is_pm_fid(smc_fid)) {
diff --git a/services/spd/opteed/opteed_main.c b/services/spd/opteed/opteed_main.c
index a9e4ece..ac58e04 100644
--- a/services/spd/opteed/opteed_main.c
+++ b/services/spd/opteed/opteed_main.c
@@ -187,14 +187,14 @@
  * state. Lastly it will also return any information that OPTEE needs to do
  * the work assigned to it.
  ******************************************************************************/
-static uint64_t opteed_smc_handler(uint32_t smc_fid,
-			 uint64_t x1,
-			 uint64_t x2,
-			 uint64_t x3,
-			 uint64_t x4,
+static uintptr_t opteed_smc_handler(uint32_t smc_fid,
+			 u_register_t x1,
+			 u_register_t x2,
+			 u_register_t x3,
+			 u_register_t x4,
 			 void *cookie,
 			 void *handle,
-			 uint64_t flags)
+			 u_register_t flags)
 {
 	cpu_context_t *ns_cpu_context;
 	uint32_t linear_id = plat_my_core_pos();
diff --git a/services/spd/opteed/opteed_pm.c b/services/spd/opteed/opteed_pm.c
index 2420b1e..7efc234 100644
--- a/services/spd/opteed/opteed_pm.c
+++ b/services/spd/opteed/opteed_pm.c
@@ -16,7 +16,7 @@
  * The target cpu is being turned on. Allow the OPTEED/OPTEE to perform any
  * actions needed. Nothing at the moment.
  ******************************************************************************/
-static void opteed_cpu_on_handler(uint64_t target_cpu)
+static void opteed_cpu_on_handler(u_register_t target_cpu)
 {
 }
 
@@ -24,7 +24,7 @@
  * This cpu is being turned off. Allow the OPTEED/OPTEE to perform any actions
  * needed
  ******************************************************************************/
-static int32_t opteed_cpu_off_handler(uint64_t unused)
+static int32_t opteed_cpu_off_handler(u_register_t unused)
 {
 	int32_t rc = 0;
 	uint32_t linear_id = plat_my_core_pos();
@@ -57,7 +57,7 @@
  * This cpu is being suspended. S-EL1 state must have been saved in the
  * resident cpu (mpidr format) if it is a UP/UP migratable OPTEE.
  ******************************************************************************/
-static void opteed_cpu_suspend_handler(uint64_t max_off_pwrlvl)
+static void opteed_cpu_suspend_handler(u_register_t max_off_pwrlvl)
 {
 	int32_t rc = 0;
 	uint32_t linear_id = plat_my_core_pos();
@@ -87,7 +87,7 @@
  * after initialising minimal architectural state that guarantees safe
  * execution.
  ******************************************************************************/
-static void opteed_cpu_on_finish_handler(uint64_t unused)
+static void opteed_cpu_on_finish_handler(u_register_t unused)
 {
 	int32_t rc = 0;
 	uint32_t linear_id = plat_my_core_pos();
@@ -123,7 +123,7 @@
  * completed the preceding suspend call. Use that context to program an entry
  * into OPTEE to allow it to do any remaining book keeping
  ******************************************************************************/
-static void opteed_cpu_suspend_finish_handler(uint64_t max_off_pwrlvl)
+static void opteed_cpu_suspend_finish_handler(u_register_t max_off_pwrlvl)
 {
 	int32_t rc = 0;
 	uint32_t linear_id = plat_my_core_pos();
@@ -154,7 +154,7 @@
  * Return the type of OPTEE the OPTEED is dealing with. Report the current
  * resident cpu (mpidr format) if it is a UP/UP migratable OPTEE.
  ******************************************************************************/
-static int32_t opteed_cpu_migrate_info(uint64_t *resident_cpu)
+static int32_t opteed_cpu_migrate_info(u_register_t *resident_cpu)
 {
 	return OPTEE_MIGRATE_INFO;
 }
diff --git a/services/spd/tlkd/tlkd_main.c b/services/spd/tlkd/tlkd_main.c
index 961fd18..5090f06 100644
--- a/services/spd/tlkd/tlkd_main.c
+++ b/services/spd/tlkd/tlkd_main.c
@@ -133,14 +133,14 @@
  * will also return any information that the secure payload needs to do the
  * work assigned to it.
  ******************************************************************************/
-static uint64_t tlkd_smc_handler(uint32_t smc_fid,
-			 uint64_t x1,
-			 uint64_t x2,
-			 uint64_t x3,
-			 uint64_t x4,
+static uintptr_t tlkd_smc_handler(uint32_t smc_fid,
+			 u_register_t x1,
+			 u_register_t x2,
+			 u_register_t x3,
+			 u_register_t x4,
 			 void *cookie,
 			 void *handle,
-			 uint64_t flags)
+			 u_register_t flags)
 {
 	cpu_context_t *ns_cpu_context;
 	gp_regs_t *gp_regs;
diff --git a/services/spd/tlkd/tlkd_pm.c b/services/spd/tlkd/tlkd_pm.c
index 8b4c457..2cd2fbb 100644
--- a/services/spd/tlkd/tlkd_pm.c
+++ b/services/spd/tlkd/tlkd_pm.c
@@ -22,7 +22,7 @@
  * Return the type of payload TLKD is dealing with. Report the current
  * resident cpu (mpidr format) if it is a UP/UP migratable payload.
  ******************************************************************************/
-static int32_t cpu_migrate_info(uint64_t *resident_cpu)
+static int32_t cpu_migrate_info(u_register_t *resident_cpu)
 {
 	/* the payload runs only on CPU0 */
 	*resident_cpu = MPIDR_CPU0;
@@ -35,7 +35,7 @@
  * This cpu is being suspended. Inform TLK of the SYSTEM_SUSPEND event, so
  * that it can pass this information to its Trusted Apps.
  ******************************************************************************/
-static void cpu_suspend_handler(uint64_t suspend_level)
+static void cpu_suspend_handler(u_register_t suspend_level)
 {
 	gp_regs_t *gp_regs;
 	int cpu = read_mpidr() & MPIDR_CPU_MASK;
@@ -67,7 +67,7 @@
  * This cpu is being resumed. Inform TLK of the SYSTEM_SUSPEND exit, so
  * that it can pass this information to its Trusted Apps.
  ******************************************************************************/
-static void cpu_resume_handler(uint64_t suspend_level)
+static void cpu_resume_handler(u_register_t suspend_level)
 {
 	gp_regs_t *gp_regs;
 	int cpu = read_mpidr() & MPIDR_CPU_MASK;
diff --git a/services/spd/trusty/trusty.c b/services/spd/trusty/trusty.c
index f5501c9..48a2611 100644
--- a/services/spd/trusty/trusty.c
+++ b/services/spd/trusty/trusty.c
@@ -212,14 +212,14 @@
 	SMC_RET0(handle);
 }
 
-static uint64_t trusty_smc_handler(uint32_t smc_fid,
-			 uint64_t x1,
-			 uint64_t x2,
-			 uint64_t x3,
-			 uint64_t x4,
+static uintptr_t trusty_smc_handler(uint32_t smc_fid,
+			 u_register_t x1,
+			 u_register_t x2,
+			 u_register_t x3,
+			 u_register_t x4,
 			 void *cookie,
 			 void *handle,
-			 uint64_t flags)
+			 u_register_t flags)
 {
 	struct args ret;
 	uint32_t vmid = 0;
@@ -347,14 +347,14 @@
 	}
 }
 
-static int32_t trusty_cpu_off_handler(uint64_t unused)
+static int32_t trusty_cpu_off_handler(u_register_t unused)
 {
 	trusty_cpu_suspend(1);
 
 	return 0;
 }
 
-static void trusty_cpu_on_finish_handler(uint64_t unused)
+static void trusty_cpu_on_finish_handler(u_register_t unused)
 {
 	struct trusty_cpu_ctx *ctx = get_trusty_ctx();
 
@@ -365,12 +365,12 @@
 	}
 }
 
-static void trusty_cpu_suspend_handler(uint64_t unused)
+static void trusty_cpu_suspend_handler(u_register_t unused)
 {
 	trusty_cpu_suspend(0);
 }
 
-static void trusty_cpu_suspend_finish_handler(uint64_t unused)
+static void trusty_cpu_suspend_finish_handler(u_register_t unused)
 {
 	trusty_cpu_resume(0);
 }
diff --git a/services/spd/tspd/tspd_main.c b/services/spd/tspd/tspd_main.c
index 279da98..8cb23b9 100644
--- a/services/spd/tspd/tspd_main.c
+++ b/services/spd/tspd/tspd_main.c
@@ -273,14 +273,14 @@
  * will also return any information that the secure payload needs to do the
  * work assigned to it.
  ******************************************************************************/
-static uint64_t tspd_smc_handler(uint32_t smc_fid,
-			 uint64_t x1,
-			 uint64_t x2,
-			 uint64_t x3,
-			 uint64_t x4,
+static uintptr_t tspd_smc_handler(uint32_t smc_fid,
+			 u_register_t x1,
+			 u_register_t x2,
+			 u_register_t x3,
+			 u_register_t x4,
 			 void *cookie,
 			 void *handle,
-			 uint64_t flags)
+			 u_register_t flags)
 {
 	cpu_context_t *ns_cpu_context;
 	uint32_t linear_id = plat_my_core_pos(), ns;
diff --git a/services/spd/tspd/tspd_pm.c b/services/spd/tspd/tspd_pm.c
index 5fdd3dc..9414c15 100644
--- a/services/spd/tspd/tspd_pm.c
+++ b/services/spd/tspd/tspd_pm.c
@@ -17,7 +17,7 @@
  * The target cpu is being turned on. Allow the TSPD/TSP to perform any actions
  * needed. Nothing at the moment.
  ******************************************************************************/
-static void tspd_cpu_on_handler(uint64_t target_cpu)
+static void tspd_cpu_on_handler(u_register_t target_cpu)
 {
 }
 
@@ -25,7 +25,7 @@
  * This cpu is being turned off. Allow the TSPD/TSP to perform any actions
  * needed
  ******************************************************************************/
-static int32_t tspd_cpu_off_handler(uint64_t unused)
+static int32_t tspd_cpu_off_handler(u_register_t unused)
 {
 	int32_t rc = 0;
 	uint32_t linear_id = plat_my_core_pos();
@@ -64,7 +64,7 @@
  * This cpu is being suspended. S-EL1 state must have been saved in the
  * resident cpu (mpidr format) if it is a UP/UP migratable TSP.
  ******************************************************************************/
-static void tspd_cpu_suspend_handler(uint64_t max_off_pwrlvl)
+static void tspd_cpu_suspend_handler(u_register_t max_off_pwrlvl)
 {
 	int32_t rc = 0;
 	uint32_t linear_id = plat_my_core_pos();
@@ -100,7 +100,7 @@
  * after initialising minimal architectural state that guarantees safe
  * execution.
  ******************************************************************************/
-static void tspd_cpu_on_finish_handler(uint64_t unused)
+static void tspd_cpu_on_finish_handler(u_register_t unused)
 {
 	int32_t rc = 0;
 	uint32_t linear_id = plat_my_core_pos();
@@ -145,7 +145,7 @@
  * completed the preceding suspend call. Use that context to program an entry
  * into the TSP to allow it to do any remaining book keeping
  ******************************************************************************/
-static void tspd_cpu_suspend_finish_handler(uint64_t max_off_pwrlvl)
+static void tspd_cpu_suspend_finish_handler(u_register_t max_off_pwrlvl)
 {
 	int32_t rc = 0;
 	uint32_t linear_id = plat_my_core_pos();
@@ -176,7 +176,7 @@
  * Return the type of TSP the TSPD is dealing with. Report the current resident
  * cpu (mpidr format) if it is a UP/UP migratable TSP.
  ******************************************************************************/
-static int32_t tspd_cpu_migrate_info(uint64_t *resident_cpu)
+static int32_t tspd_cpu_migrate_info(u_register_t *resident_cpu)
 {
 	return TSP_MIGRATE_INFO;
 }