diff --git a/plat/nvidia/tegra/soc/t186/plat_sip_calls.c b/plat/nvidia/tegra/soc/t186/plat_sip_calls.c
index 955029e..4de8a9e 100644
--- a/plat/nvidia/tegra/soc/t186/plat_sip_calls.c
+++ b/plat/nvidia/tegra/soc/t186/plat_sip_calls.c
@@ -23,7 +23,7 @@
 /*******************************************************************************
  * Offset to read the ref_clk counter value
  ******************************************************************************/
-#define REF_CLK_OFFSET		4
+#define REF_CLK_OFFSET		4ULL
 
 /*******************************************************************************
  * Tegra186 SiP SMCs
@@ -35,7 +35,7 @@
 #define TEGRA_SIP_MCE_CMD_READ_CSTATE_STATS		0xC2FFFF03
 #define TEGRA_SIP_MCE_CMD_WRITE_CSTATE_STATS		0xC2FFFF04
 #define TEGRA_SIP_MCE_CMD_IS_SC7_ALLOWED		0xC2FFFF05
-#define TEGRA_SIP_MCE_CMD_ONLINE_CORE			0xC2FFFF06
+
 #define TEGRA_SIP_MCE_CMD_CC3_CTRL			0xC2FFFF07
 #define TEGRA_SIP_MCE_CMD_ECHO_DATA			0xC2FFFF08
 #define TEGRA_SIP_MCE_CMD_READ_VERSIONS			0xC2FFFF09
@@ -52,7 +52,7 @@
 /*******************************************************************************
  * This function is responsible for handling all T186 SiP calls
  ******************************************************************************/
-int plat_sip_handler(uint32_t smc_fid,
+int32_t plat_sip_handler(uint32_t smc_fid,
 		     uint64_t x1,
 		     uint64_t x2,
 		     uint64_t x3,
@@ -61,24 +61,30 @@
 		     void *handle,
 		     uint64_t flags)
 {
-	int mce_ret;
-	int impl, cpu;
+	int32_t mce_ret, ret = 0;
+	uint32_t impl, cpu;
 	uint32_t base, core_clk_ctr, ref_clk_ctr;
+	uint32_t local_smc_fid = smc_fid;
+	uint64_t local_x1 = x1, local_x2 = x2, local_x3 = x3;
+
+	(void)x4;
+	(void)cookie;
+	(void)flags;
 
 	if (((smc_fid >> FUNCID_CC_SHIFT) & FUNCID_CC_MASK) == SMC_32) {
 		/* 32-bit function, clear top parameter bits */
 
-		x1 = (uint32_t)x1;
-		x2 = (uint32_t)x2;
-		x3 = (uint32_t)x3;
+		local_x1 = (uint32_t)x1;
+		local_x2 = (uint32_t)x2;
+		local_x3 = (uint32_t)x3;
 	}
 
 	/*
 	 * Convert SMC FID to SMC64, to support SMC32/SMC64 configurations
 	 */
-	smc_fid |= (SMC_64 << FUNCID_CC_SHIFT);
+	local_smc_fid |= (SMC_64 << FUNCID_CC_SHIFT);
 
-	switch (smc_fid) {
+	switch (local_smc_fid) {
 	/*
 	 * Micro Coded Engine (MCE) commands reside in the 0x82FFFF00 -
 	 * 0x82FFFFFF SiP SMC space
@@ -103,14 +109,13 @@
 	case TEGRA_SIP_MCE_CMD_MISC_CCPLEX:
 
 		/* clean up the high bits */
-		smc_fid &= MCE_CMD_MASK;
+		local_smc_fid &= MCE_CMD_MASK;
 
 		/* execute the command and store the result */
-		mce_ret = mce_command_handler(smc_fid, x1, x2, x3);
-		write_ctx_reg(get_gpregs_ctx(handle), CTX_GPREG_X0,
-			      (uint64_t)mce_ret);
-
-		return 0;
+		mce_ret = mce_command_handler(local_smc_fid, local_x1, local_x2, local_x3);
+		write_ctx_reg(get_gpregs_ctx(handle),
+			      CTX_GPREG_X0, (uint64_t)(mce_ret));
+		break;
 
 	/*
 	 * This function ID reads the Activity monitor's core/ref clock
@@ -125,28 +130,30 @@
 		impl = ((uint32_t)x2 >> MIDR_IMPL_SHIFT) & MIDR_IMPL_MASK;
 
 		/* sanity check target CPU number */
-		if (cpu > PLATFORM_MAX_CPUS_PER_CLUSTER)
-			return -EINVAL;
+		if (cpu > (uint32_t)PLATFORM_MAX_CPUS_PER_CLUSTER) {
+			ret = -EINVAL;
+		} else {
+			/* get the base address for the current CPU */
+			base = (impl == DENVER_IMPL) ? TEGRA_DENVER_ACTMON_CTR_BASE :
+				TEGRA_ARM_ACTMON_CTR_BASE;
 
-		/* get the base address for the current CPU */
-		base = (impl == DENVER_IMPL) ? TEGRA_DENVER_ACTMON_CTR_BASE :
-			TEGRA_ARM_ACTMON_CTR_BASE;
+			/* read the clock counter values */
+			core_clk_ctr = mmio_read_32(base + (8ULL * cpu));
+			ref_clk_ctr = mmio_read_32(base + (8ULL * cpu) + REF_CLK_OFFSET);
 
-		/* read the clock counter values */
-		core_clk_ctr = mmio_read_32(base + (8 * cpu));
-		ref_clk_ctr = mmio_read_32(base + (8 * cpu) + REF_CLK_OFFSET);
+			/* return the counter values as two different parameters */
+			write_ctx_reg(get_gpregs_ctx(handle),
+				      CTX_GPREG_X1, (core_clk_ctr));
+			write_ctx_reg(get_gpregs_ctx(handle),
+				      CTX_GPREG_X2, (ref_clk_ctr));
+		}
 
-		/* return the counter values as two different parameters */
-		write_ctx_reg(get_gpregs_ctx(handle), CTX_GPREG_X1,
-			      (uint64_t)core_clk_ctr);
-		write_ctx_reg(get_gpregs_ctx(handle), CTX_GPREG_X2,
-			      (uint64_t)ref_clk_ctr);
-
-		return 0;
+		break;
 
 	default:
+		ret = -ENOTSUP;
 		break;
 	}
 
-	return -ENOTSUP;
+	return ret;
 }