diff --git a/plat/intel/soc/common/soc/socfpga_mailbox.c b/plat/intel/soc/common/soc/socfpga_mailbox.c
index 9ba9b3171..29f3df28d 100644
--- a/plat/intel/soc/common/soc/socfpga_mailbox.c
+++ b/plat/intel/soc/common/soc/socfpga_mailbox.c
@@ -54,7 +54,7 @@ static int write_mailbox_cmd_buffer(uint32_t *cin, uint32_t cout,
 		if (is_mailbox_cmdbuf_full(*cin)) {
 			if (!(*is_doorbell_triggered)) {
 				mmio_write_32(MBOX_OFFSET +
-					      MBOX_DOORBELL_TO_SDM, 1);
+					      MBOX_DOORBELL_TO_SDM, 1U);
 				*is_doorbell_triggered = true;
 			}
 			mdelay(10U);
@@ -108,7 +108,7 @@ static int fill_mailbox_circular_buffer(uint32_t header_cmd, uint32_t *args,
 	}
 
 	if (!is_doorbell_triggered) {
-		mmio_write_32(MBOX_OFFSET + MBOX_DOORBELL_TO_SDM, 1);
+		mmio_write_32(MBOX_OFFSET + MBOX_DOORBELL_TO_SDM, 1U);
 	}
 
 	return MBOX_RET_OK;
@@ -137,8 +137,9 @@ int mailbox_read_response(uint32_t *job_id, uint32_t *response, int resp_len)
 	int resp_data = 0;
 	int ret_resp_len;
 
-	if (mmio_read_32(MBOX_OFFSET + MBOX_DOORBELL_FROM_SDM))
-		mmio_write_32(MBOX_OFFSET + MBOX_DOORBELL_FROM_SDM, 0);
+	if (mmio_read_32(MBOX_OFFSET + MBOX_DOORBELL_FROM_SDM) == 1U) {
+		mmio_write_32(MBOX_OFFSET + MBOX_DOORBELL_FROM_SDM, 0U);
+	}
 
 	rin = mmio_read_32(MBOX_OFFSET + MBOX_RIN);
 	rout = mmio_read_32(MBOX_OFFSET + MBOX_ROUT);
@@ -189,7 +190,7 @@ int mailbox_poll_response(uint32_t job_id, int urgent, uint32_t *response,
 
 		do {
 			if (mmio_read_32(MBOX_OFFSET + MBOX_DOORBELL_FROM_SDM)
-			    & 1) {
+				== 1U) {
 				break;
 			}
 			mdelay(10U);
@@ -199,18 +200,18 @@ int mailbox_poll_response(uint32_t job_id, int urgent, uint32_t *response,
 			break;
 		}
 
-		mmio_write_32(MBOX_OFFSET + MBOX_DOORBELL_FROM_SDM, 0);
+		mmio_write_32(MBOX_OFFSET + MBOX_DOORBELL_FROM_SDM, 0U);
 
-		if (urgent & 1) {
-			mdelay(5);
+		if ((urgent & 1) != 0) {
+			mdelay(5U);
 			if ((mmio_read_32(MBOX_OFFSET + MBOX_STATUS) &
 				MBOX_STATUS_UA_MASK) ^
 				(urgent & MBOX_STATUS_UA_MASK)) {
-				mmio_write_32(MBOX_OFFSET + MBOX_URG, 0);
+				mmio_write_32(MBOX_OFFSET + MBOX_URG, 0U);
 				return MBOX_RET_OK;
 			}
 
-			mmio_write_32(MBOX_OFFSET + MBOX_URG, 0);
+			mmio_write_32(MBOX_OFFSET + MBOX_URG, 0U);
 			INFO("Error: Mailbox did not get UA");
 			return MBOX_RET_ERROR;
 		}
@@ -226,8 +227,9 @@ int mailbox_poll_response(uint32_t job_id, int urgent, uint32_t *response,
 			mmio_write_32(MBOX_OFFSET + MBOX_ROUT, rout);
 
 			if (MBOX_RESP_CLIENT_ID(resp_data) != MBOX_ATF_CLIENT_ID
-				|| MBOX_RESP_JOB_ID(resp_data) != job_id)
+				|| MBOX_RESP_JOB_ID(resp_data) != job_id) {
 				continue;
+			}
 
 			ret_resp_len = MBOX_RESP_LEN(resp_data);
 
@@ -308,7 +310,7 @@ int mailbox_send_cmd_async(uint32_t *job_id, unsigned int cmd, uint32_t *args,
 		return status;
 	}
 
-	*job_id = (*job_id + 1) % MBOX_MAX_IND_JOB_ID;
+	*job_id = (*job_id + 1U) % MBOX_MAX_IND_JOB_ID;
 
 	return MBOX_RET_OK;
 }
@@ -318,11 +320,11 @@ int mailbox_send_cmd(uint32_t job_id, unsigned int cmd, uint32_t *args,
 {
 	int status = 0;
 
-	if (urgent) {
+	if (urgent != 0) {
 		urgent |= mmio_read_32(MBOX_OFFSET + MBOX_STATUS) &
 					MBOX_STATUS_UA_MASK;
 		mmio_write_32(MBOX_OFFSET + MBOX_URG, cmd);
-		mmio_write_32(MBOX_OFFSET + MBOX_DOORBELL_TO_SDM, 1);
+		mmio_write_32(MBOX_OFFSET + MBOX_DOORBELL_TO_SDM, 1U);
 	}
 
 	else {
@@ -333,8 +335,9 @@ int mailbox_send_cmd(uint32_t job_id, unsigned int cmd, uint32_t *args,
 			cmd, args, len);
 	}
 
-	if (status)
+	if (status != 0) {
 		return status;
+	}
 
 	status = mailbox_poll_response(job_id, urgent, response, resp_len);
 
@@ -375,12 +378,12 @@ void mailbox_set_qspi_close(void)
 				CMD_CASUAL, NULL, 0);
 }
 
-void mailbox_qspi_set_cs(int device_select)
+void mailbox_qspi_set_cs(uint32_t device_select)
 {
-	uint32_t cs_setting = device_select;
+	uint32_t cs_setting;
 
 	/* QSPI device select settings at 31:28 */
-	cs_setting = (cs_setting << 28);
+	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);
@@ -415,18 +418,21 @@ int mailbox_rsu_status(uint32_t *resp_buf, uint32_t resp_buf_len)
 	int ret;
 	struct rsu_status_info *info = (struct rsu_status_info *)resp_buf;
 
-	info->retry_counter = ~0;
+	info->retry_counter = ~0U;
 
 	ret = mailbox_send_cmd(MBOX_JOB_ID, MBOX_RSU_STATUS, NULL, 0,
 				CMD_CASUAL, (uint32_t *)resp_buf,
 				resp_buf_len);
 
-	if (ret < 0)
+	if (ret < 0) {
 		return ret;
+	}
 
-	if (info->retry_counter != ~0)
-		if (!(info->version & RSU_VERSION_ACMF_MASK))
+	if (info->retry_counter != ~0U) {
+		if ((info->version & RSU_VERSION_ACMF_MASK) == 0U) {
 			info->version |= RSU_VERSION_ACMF;
+		}
+	}
 
 	return ret;
 }
@@ -451,14 +457,15 @@ int mailbox_init(void)
 
 	mailbox_set_int(MBOX_INT_FLAG_COE | MBOX_INT_FLAG_RIE |
 			MBOX_INT_FLAG_UAE);
-	mmio_write_32(MBOX_OFFSET + MBOX_URG, 0);
-	mmio_write_32(MBOX_OFFSET + MBOX_DOORBELL_FROM_SDM, 0);
+	mmio_write_32(MBOX_OFFSET + MBOX_URG, 0U);
+	mmio_write_32(MBOX_OFFSET + MBOX_DOORBELL_FROM_SDM, 0U);
 
-	status = mailbox_send_cmd(0, MBOX_CMD_RESTART, NULL, 0,
+	status = mailbox_send_cmd(0U, MBOX_CMD_RESTART, NULL, 0,
 					CMD_URGENT, NULL, 0);
 
-	if (status)
+	if (status != 0) {
 		return status;
+	}
 
 	mailbox_set_int(MBOX_INT_FLAG_COE | MBOX_INT_FLAG_RIE |
 			MBOX_INT_FLAG_UAE);
@@ -474,24 +481,29 @@ int intel_mailbox_get_config_status(uint32_t cmd)
 	status = mailbox_send_cmd(MBOX_JOB_ID, cmd, NULL, 0, CMD_CASUAL, response,
 				ARRAY_SIZE(response));
 
-	if (status < 0)
+	if (status < 0) {
 		return status;
+	}
 
 	res = response[RECONFIG_STATUS_STATE];
-	if (res && res != MBOX_CFGSTAT_STATE_CONFIG)
+	if ((res != 0U) && (res != MBOX_CFGSTAT_STATE_CONFIG)) {
 		return res;
+	}
 
 	res = response[RECONFIG_STATUS_PIN_STATUS];
-	if (!(res & PIN_STATUS_NSTATUS))
+	if ((res & PIN_STATUS_NSTATUS) == 0U) {
 		return MBOX_CFGSTAT_STATE_ERROR_HARDWARE;
+	}
 
 	res = response[RECONFIG_STATUS_SOFTFUNC_STATUS];
-	if (res & SOFTFUNC_STATUS_SEU_ERROR)
+	if ((res & SOFTFUNC_STATUS_SEU_ERROR) != 0U) {
 		return MBOX_CFGSTAT_STATE_ERROR_HARDWARE;
+	}
 
-	if ((res & SOFTFUNC_STATUS_CONF_DONE) &&
-		(res & SOFTFUNC_STATUS_INIT_DONE))
+	if ((res & SOFTFUNC_STATUS_CONF_DONE) != 0U &&
+		(res & SOFTFUNC_STATUS_INIT_DONE) != 0U) {
 		return MBOX_RET_OK;
+	}
 
 	return MBOX_CFGSTAT_STATE_CONFIG;
 }
@@ -500,8 +512,9 @@ int intel_mailbox_is_fpga_not_ready(void)
 {
 	int ret = intel_mailbox_get_config_status(MBOX_RECONFIG_STATUS);
 
-	if (ret && ret != MBOX_CFGSTAT_STATE_CONFIG)
+	if ((ret != MBOX_RET_OK) && (ret != MBOX_CFGSTAT_STATE_CONFIG)) {
 		ret = intel_mailbox_get_config_status(MBOX_CONFIG_STATUS);
+	}
 
 	return ret;
 }