diff --git a/plat/intel/soc/common/include/socfpga_mailbox.h b/plat/intel/soc/common/include/socfpga_mailbox.h
index 3a2bf309e..923c4f154 100644
--- a/plat/intel/soc/common/include/socfpga_mailbox.h
+++ b/plat/intel/soc/common/include/socfpga_mailbox.h
@@ -136,17 +136,22 @@
 
 /* Mailbox Function Definitions */
 
-void mailbox_set_int(int interrupt_input);
+void mailbox_set_int(uint32_t interrupt_input);
 int mailbox_init(void);
 void mailbox_set_qspi_close(void);
 void mailbox_set_qspi_open(void);
 void mailbox_set_qspi_direct(void);
-int mailbox_send_cmd(uint32_t job_id, unsigned int cmd, uint32_t *args,
-			int len, int urgent, uint32_t *response, int resp_len);
-int mailbox_send_cmd_async(uint32_t *job_id, unsigned int cmd, uint32_t *args,
-				int len, int indirect);
-int mailbox_read_response(uint32_t *job_id, uint32_t *response, int resp_len);
-int iterate_resp(int mbox_resp_len, uint32_t *resp_buf, int resp_len);
+
+int mailbox_send_cmd(uint32_t job_id, uint32_t cmd, uint32_t *args,
+			unsigned int len, uint32_t urgent, uint32_t *response,
+			unsigned int resp_len);
+int mailbox_send_cmd_async(uint32_t *job_id, uint32_t cmd, uint32_t *args,
+			unsigned int len, unsigned int indirect);
+int mailbox_read_response(uint32_t *job_id, uint32_t *response,
+			unsigned int resp_len);
+unsigned int iterate_resp(uint32_t mbox_resp_len, uint32_t *resp_buf,
+			unsigned int resp_len);
+
 void mailbox_reset_cold(void);
 void mailbox_clear_response(void);
 
diff --git a/plat/intel/soc/common/soc/socfpga_mailbox.c b/plat/intel/soc/common/soc/socfpga_mailbox.c
index 29f3df28d..aec94af94 100644
--- a/plat/intel/soc/common/soc/socfpga_mailbox.c
+++ b/plat/intel/soc/common/soc/socfpga_mailbox.c
@@ -28,7 +28,7 @@ static bool is_mailbox_cmdbuf_empty(uint32_t cin)
 
 static int wait_for_mailbox_cmdbuf_empty(uint32_t cin)
 {
-	uint32_t timeout = 200U;
+	unsigned int timeout = 200U;
 
 	do {
 		if (is_mailbox_cmdbuf_empty(cin)) {
@@ -48,7 +48,7 @@ static int write_mailbox_cmd_buffer(uint32_t *cin, uint32_t cout,
 				    uint32_t data,
 				    bool *is_doorbell_triggered)
 {
-	uint32_t timeout = 100U;
+	unsigned int timeout = 100U;
 
 	do {
 		if (is_mailbox_cmdbuf_full(*cin)) {
@@ -81,10 +81,10 @@ static int write_mailbox_cmd_buffer(uint32_t *cin, uint32_t cout,
 }
 
 static int fill_mailbox_circular_buffer(uint32_t header_cmd, uint32_t *args,
-					int len)
+					unsigned int len)
 {
 	uint32_t sdm_read_offset, cmd_free_offset;
-	uint32_t i;
+	unsigned int i;
 	int ret;
 	bool is_doorbell_triggered = false;
 
@@ -130,12 +130,13 @@ restart_mailbox:
 	return MBOX_TIMEOUT;
 }
 
-int mailbox_read_response(uint32_t *job_id, uint32_t *response, int resp_len)
+int mailbox_read_response(unsigned int *job_id, uint32_t *response,
+				unsigned int resp_len)
 {
-	int rin = 0;
-	int rout = 0;
-	int resp_data = 0;
-	int ret_resp_len;
+	uint32_t rin;
+	uint32_t rout;
+	uint32_t resp_data;
+	unsigned int ret_resp_len;
 
 	if (mmio_read_32(MBOX_OFFSET + MBOX_DOORBELL_FROM_SDM) == 1U) {
 		mmio_write_32(MBOX_OFFSET + MBOX_DOORBELL_FROM_SDM, 0U);
@@ -146,7 +147,7 @@ int mailbox_read_response(uint32_t *job_id, uint32_t *response, int resp_len)
 
 	if (rout != rin) {
 		resp_data = mmio_read_32(MBOX_OFFSET +
-				    MBOX_RESP_BUFFER + ((rout++)*4));
+				    MBOX_RESP_BUFFER + ((rout++)*4U));
 
 		rout %= MBOX_RESP_BUFFER_SIZE;
 		mmio_write_32(MBOX_OFFSET + MBOX_ROUT, rout);
@@ -160,12 +161,12 @@ int mailbox_read_response(uint32_t *job_id, uint32_t *response, int resp_len)
 
 		ret_resp_len = MBOX_RESP_LEN(resp_data);
 
-		if (ret_resp_len != 0) {
+		if (ret_resp_len != 0U) {
 			ret_resp_len = iterate_resp(ret_resp_len, response,
 						    resp_len);
 		}
 
-		if (MBOX_RESP_ERR(resp_data) > 0) {
+		if (MBOX_RESP_ERR(resp_data) > 0U) {
 			INFO("Error in response: %x\n", resp_data);
 			return -MBOX_RESP_ERR(resp_data);
 		}
@@ -176,15 +177,15 @@ int mailbox_read_response(uint32_t *job_id, uint32_t *response, int resp_len)
 }
 
 
-int mailbox_poll_response(uint32_t job_id, int urgent, uint32_t *response,
-				int resp_len)
+int mailbox_poll_response(uint32_t job_id, uint32_t urgent, uint32_t *response,
+				unsigned int resp_len)
 {
-	uint32_t timeout = 40U;
-	uint32_t sdm_loop = 255U;
-	int rin = 0;
-	int rout = 0;
-	int resp_data = 0;
-	int ret_resp_len;
+	unsigned int timeout = 40U;
+	unsigned int sdm_loop = 255U;
+	unsigned int ret_resp_len;
+	uint32_t rin;
+	uint32_t rout;
+	uint32_t resp_data;
 
 	while (sdm_loop != 0U) {
 
@@ -202,7 +203,7 @@ int mailbox_poll_response(uint32_t job_id, int urgent, uint32_t *response,
 
 		mmio_write_32(MBOX_OFFSET + MBOX_DOORBELL_FROM_SDM, 0U);
 
-		if ((urgent & 1) != 0) {
+		if ((urgent & 1U) != 0U) {
 			mdelay(5U);
 			if ((mmio_read_32(MBOX_OFFSET + MBOX_STATUS) &
 				MBOX_STATUS_UA_MASK) ^
@@ -221,7 +222,7 @@ int mailbox_poll_response(uint32_t job_id, int urgent, uint32_t *response,
 
 		while (rout != rin) {
 			resp_data = mmio_read_32(MBOX_OFFSET +
-					    MBOX_RESP_BUFFER + ((rout++)*4));
+					    MBOX_RESP_BUFFER + ((rout++)*4U));
 
 			rout %= MBOX_RESP_BUFFER_SIZE;
 			mmio_write_32(MBOX_OFFSET + MBOX_ROUT, rout);
@@ -233,13 +234,13 @@ int mailbox_poll_response(uint32_t job_id, int urgent, uint32_t *response,
 
 			ret_resp_len = MBOX_RESP_LEN(resp_data);
 
-			if (ret_resp_len != 0) {
+			if (ret_resp_len != 0U) {
 				ret_resp_len = iterate_resp(ret_resp_len,
 							    response,
 							    resp_len);
 			}
 
-			if (MBOX_RESP_ERR(resp_data) > 0) {
+			if (MBOX_RESP_ERR(resp_data) > 0U) {
 				INFO("Error in response: %x\n", resp_data);
 				return -MBOX_RESP_ERR(resp_data);
 			}
@@ -254,20 +255,22 @@ int mailbox_poll_response(uint32_t job_id, int urgent, uint32_t *response,
 	return MBOX_TIMEOUT;
 }
 
-int iterate_resp(int mbox_resp_len, uint32_t *resp_buf, int resp_len)
+unsigned int iterate_resp(uint32_t mbox_resp_len, uint32_t *resp_buf,
+			unsigned int resp_len)
 {
-	uint32_t timeout;
-	int resp_data = 0, total_resp_len = 0;
-	int rin = mmio_read_32(MBOX_OFFSET + MBOX_RIN);
-	int rout = mmio_read_32(MBOX_OFFSET + MBOX_ROUT);
+	unsigned int timeout, total_resp_len = 0U;
+	uint32_t resp_data;
+	uint32_t rin = mmio_read_32(MBOX_OFFSET + MBOX_RIN);
+	uint32_t rout = mmio_read_32(MBOX_OFFSET + MBOX_ROUT);
 
-	while (mbox_resp_len > 0) {
+	while (mbox_resp_len > 0U) {
 		timeout = 100U;
 		mbox_resp_len--;
 		resp_data = mmio_read_32(MBOX_OFFSET +
 					MBOX_RESP_BUFFER +
-					(rout)*4);
-		if (resp_buf && resp_len) {
+					(rout)*4U);
+
+		if ((resp_buf != NULL) && (resp_len != 0U)) {
 			*(resp_buf + total_resp_len)
 					= resp_data;
 			resp_len--;
@@ -285,7 +288,7 @@ int iterate_resp(int mbox_resp_len, uint32_t *resp_buf, int resp_len)
 				break;
 			}
 			timeout--;
-		} while ((mbox_resp_len > 0) && (timeout != 0U));
+		} while ((mbox_resp_len > 0U) && (timeout != 0U));
 
 		if (timeout == 0U) {
 			INFO("Timed out waiting for SDM\n");
@@ -295,8 +298,8 @@ int iterate_resp(int mbox_resp_len, uint32_t *resp_buf, int resp_len)
 	return total_resp_len;
 }
 
-int mailbox_send_cmd_async(uint32_t *job_id, unsigned int cmd, uint32_t *args,
-			  int len, int indirect)
+int mailbox_send_cmd_async(uint32_t *job_id, uint32_t cmd, uint32_t *args,
+			  unsigned int len, unsigned int indirect)
 {
 	int status;
 
@@ -315,12 +318,13 @@ int mailbox_send_cmd_async(uint32_t *job_id, unsigned int cmd, uint32_t *args,
 	return MBOX_RET_OK;
 }
 
-int mailbox_send_cmd(uint32_t job_id, unsigned int cmd, uint32_t *args,
-			int len, int urgent, uint32_t *response, int resp_len)
+int mailbox_send_cmd(uint32_t job_id, uint32_t cmd, uint32_t *args,
+			unsigned int len, uint32_t urgent, uint32_t *response,
+			unsigned int resp_len)
 {
 	int status = 0;
 
-	if (urgent != 0) {
+	if (urgent != 0U) {
 		urgent |= mmio_read_32(MBOX_OFFSET + MBOX_STATUS) &
 					MBOX_STATUS_UA_MASK;
 		mmio_write_32(MBOX_OFFSET + MBOX_URG, cmd);
@@ -350,7 +354,7 @@ void mailbox_clear_response(void)
 		mmio_read_32(MBOX_OFFSET + MBOX_RIN));
 }
 
-void mailbox_set_int(int interrupt)
+void mailbox_set_int(uint32_t interrupt)
 {
 
 	mmio_write_32(MBOX_OFFSET+MBOX_INT, MBOX_COE_BIT(interrupt) |
@@ -361,21 +365,21 @@ void mailbox_set_int(int interrupt)
 void mailbox_set_qspi_open(void)
 {
 	mailbox_set_int(MBOX_INT_FLAG_COE | MBOX_INT_FLAG_RIE);
-	mailbox_send_cmd(MBOX_JOB_ID, MBOX_CMD_QSPI_OPEN, NULL, 0,
-				CMD_CASUAL, NULL, 0);
+	mailbox_send_cmd(MBOX_JOB_ID, MBOX_CMD_QSPI_OPEN, NULL, 0U,
+				CMD_CASUAL, NULL, 0U);
 }
 
 void mailbox_set_qspi_direct(void)
 {
-	mailbox_send_cmd(MBOX_JOB_ID, MBOX_CMD_QSPI_DIRECT, NULL, 0,
-				CMD_CASUAL, NULL, 0);
+	mailbox_send_cmd(MBOX_JOB_ID, MBOX_CMD_QSPI_DIRECT, NULL, 0U,
+				CMD_CASUAL, NULL, 0U);
 }
 
 void mailbox_set_qspi_close(void)
 {
 	mailbox_set_int(MBOX_INT_FLAG_COE | MBOX_INT_FLAG_RIE);
-	mailbox_send_cmd(MBOX_JOB_ID, MBOX_CMD_QSPI_CLOSE, NULL, 0,
-				CMD_CASUAL, NULL, 0);
+	mailbox_send_cmd(MBOX_JOB_ID, MBOX_CMD_QSPI_CLOSE, NULL, 0U,
+				CMD_CASUAL, NULL, 0U);
 }
 
 void mailbox_qspi_set_cs(uint32_t device_select)
@@ -386,20 +390,20 @@ void mailbox_qspi_set_cs(uint32_t device_select)
 	cs_setting = (device_select << 28);
 	mailbox_set_int(MBOX_INT_FLAG_COE | MBOX_INT_FLAG_RIE);
 	mailbox_send_cmd(MBOX_JOB_ID, MBOX_CMD_QSPI_SET_CS, &cs_setting,
-				1, CMD_CASUAL, NULL, 0);
+				1U, CMD_CASUAL, NULL, 0U);
 }
 
 void mailbox_reset_cold(void)
 {
 	mailbox_set_int(MBOX_INT_FLAG_COE | MBOX_INT_FLAG_RIE);
-	mailbox_send_cmd(MBOX_JOB_ID, MBOX_CMD_REBOOT_HPS, NULL, 0,
-				CMD_CASUAL, NULL, 0);
+	mailbox_send_cmd(MBOX_JOB_ID, MBOX_CMD_REBOOT_HPS, NULL, 0U,
+				CMD_CASUAL, NULL, 0U);
 }
 
-int mailbox_rsu_get_spt_offset(uint32_t *resp_buf, uint32_t resp_buf_len)
+int mailbox_rsu_get_spt_offset(uint32_t *resp_buf, unsigned int resp_buf_len)
 {
 	return mailbox_send_cmd(MBOX_JOB_ID, MBOX_GET_SUBPARTITION_TABLE,
-				NULL, 0, CMD_CASUAL, (uint32_t *)resp_buf,
+				NULL, 0U, CMD_CASUAL, resp_buf,
 				resp_buf_len);
 }
 
@@ -413,15 +417,15 @@ struct rsu_status_info {
 	uint32_t retry_counter;
 };
 
-int mailbox_rsu_status(uint32_t *resp_buf, uint32_t resp_buf_len)
+int mailbox_rsu_status(uint32_t *resp_buf, unsigned int resp_buf_len)
 {
 	int ret;
 	struct rsu_status_info *info = (struct rsu_status_info *)resp_buf;
 
 	info->retry_counter = ~0U;
 
-	ret = mailbox_send_cmd(MBOX_JOB_ID, MBOX_RSU_STATUS, NULL, 0,
-				CMD_CASUAL, (uint32_t *)resp_buf,
+	ret = mailbox_send_cmd(MBOX_JOB_ID, MBOX_RSU_STATUS, NULL, 0U,
+				CMD_CASUAL, resp_buf,
 				resp_buf_len);
 
 	if (ret < 0) {
@@ -440,28 +444,28 @@ int mailbox_rsu_status(uint32_t *resp_buf, uint32_t resp_buf_len)
 int mailbox_rsu_update(uint32_t *flash_offset)
 {
 	return mailbox_send_cmd(MBOX_JOB_ID, MBOX_RSU_UPDATE,
-				flash_offset, 2,
-				CMD_CASUAL, NULL, 0);
+				flash_offset, 2U,
+				CMD_CASUAL, NULL, 0U);
 }
 
 int mailbox_hps_stage_notify(uint32_t execution_stage)
 {
 	return mailbox_send_cmd(MBOX_JOB_ID, MBOX_HPS_STAGE_NOTIFY,
-				&execution_stage, 1, CMD_CASUAL,
-				NULL, 0);
+				&execution_stage, 1U, CMD_CASUAL,
+				NULL, 0U);
 }
 
 int mailbox_init(void)
 {
-	int status = 0;
+	int status;
 
 	mailbox_set_int(MBOX_INT_FLAG_COE | MBOX_INT_FLAG_RIE |
 			MBOX_INT_FLAG_UAE);
 	mmio_write_32(MBOX_OFFSET + MBOX_URG, 0U);
 	mmio_write_32(MBOX_OFFSET + MBOX_DOORBELL_FROM_SDM, 0U);
 
-	status = mailbox_send_cmd(0U, MBOX_CMD_RESTART, NULL, 0,
-					CMD_URGENT, NULL, 0);
+	status = mailbox_send_cmd(0U, MBOX_CMD_RESTART, NULL, 0U,
+					CMD_URGENT, NULL, 0U);
 
 	if (status != 0) {
 		return status;
@@ -478,8 +482,8 @@ int intel_mailbox_get_config_status(uint32_t cmd)
 	int status;
 	uint32_t res, response[6];
 
-	status = mailbox_send_cmd(MBOX_JOB_ID, cmd, NULL, 0, CMD_CASUAL, response,
-				ARRAY_SIZE(response));
+	status = mailbox_send_cmd(MBOX_JOB_ID, cmd, NULL, 0U, CMD_CASUAL,
+				response, ARRAY_SIZE(response));
 
 	if (status < 0) {
 		return status;
diff --git a/plat/intel/soc/common/socfpga_sip_svc.c b/plat/intel/soc/common/socfpga_sip_svc.c
index d5789f247..86a44556a 100644
--- a/plat/intel/soc/common/socfpga_sip_svc.c
+++ b/plat/intel/soc/common/socfpga_sip_svc.c
@@ -60,7 +60,7 @@ static int intel_fpga_sdm_write_buffer(struct fpga_config_info *buffer)
 
 		buffer->size_written += args[2];
 		mailbox_send_cmd_async(&send_id, MBOX_RECONFIG_DATA, args,
-					3, CMD_INDIRECT);
+					3U, CMD_INDIRECT);
 
 		buffer->subblocks_sent++;
 		max_blocks--;
@@ -190,9 +190,9 @@ static int intel_fpga_config_start(uint32_t config_type)
 
 	mailbox_clear_response();
 
-	mailbox_send_cmd(1, MBOX_CMD_CANCEL, NULL, 0, CMD_CASUAL, NULL, 0);
+	mailbox_send_cmd(1U, MBOX_CMD_CANCEL, NULL, 0U, CMD_CASUAL, NULL, 0U);
 
-	status = mailbox_send_cmd(1, MBOX_RECONFIG, NULL, 0, CMD_CASUAL,
+	status = mailbox_send_cmd(1U, MBOX_RECONFIG, NULL, 0U, CMD_CASUAL,
 			response, ARRAY_SIZE(response));
 
 	if (status < 0)
@@ -351,7 +351,7 @@ uint32_t intel_secure_reg_update(uint64_t reg_addr, uint32_t mask,
 /* Intel Remote System Update (RSU) services */
 uint64_t intel_rsu_update_address;
 
-static uint32_t intel_rsu_status(uint64_t *respbuf, uint32_t respbuf_sz)
+static uint32_t intel_rsu_status(uint64_t *respbuf, unsigned int respbuf_sz)
 {
 	if (mailbox_rsu_status((uint32_t *)respbuf, respbuf_sz) < 0)
 		return INTEL_SIP_SMC_RSU_ERROR;
@@ -384,9 +384,9 @@ static uint32_t intel_rsu_retry_counter(uint32_t *respbuf, uint32_t respbuf_sz,
 }
 
 /* Mailbox services */
-static uint32_t intel_mbox_send_cmd(uint32_t cmd, uint32_t *args, int len,
-				    int urgent, uint32_t *response,
-				    int resp_len, int *mbox_status,
+static uint32_t intel_mbox_send_cmd(uint32_t cmd, uint32_t *args, uint32_t len,
+				    uint32_t urgent, uint32_t *response,
+				    uint32_t resp_len, int *mbox_status,
 				    int *len_in_resp)
 {
 	*len_in_resp = 0;