drivers: serial: silabs: fix eusart driver when parity param is nok

When running uart_elementary on the xg22 SoC, some tests are failing due
to the lack of checks inside the configuration function. This patch adds
a check for the parity parameter.
I've also noticed an error in the ISR function where we check all the
ISR flags and not only the enabled ones. It has no impact but needs to be
changed in order to be accurate.

Signed-off-by: Martin Hoff <martin.hoff@silabs.com>

Author: Martinhoff-maker

drivers/serial/uart_silabs_eusart.c

@@ -765,7 +765,7 @@ static void eusart_isr(const struct device *dev)
 #ifdef CONFIG_UART_SILABS_EUSART_ASYNC
 	const struct eusart_config *config = dev->config;
 	EUSART_TypeDef *eusart = config->eusart;
-	uint32_t flags = EUSART_IntGet(eusart);
+	uint32_t flags = EUSART_IntGetEnabled(eusart);
 	struct dma_status stat;
 #endif
 #ifdef CONFIG_UART_INTERRUPT_DRIVEN
@@ -983,6 +983,10 @@ static int eusart_configure(const struct device *dev, const struct uart_config *
 		return -ENOSYS;
 	}
 
+	if (cfg->parity > UART_CFG_PARITY_SPACE) {
+		return -EINVAL;
+	}
+
 	if (cfg->flow_ctrl == UART_CFG_FLOW_CTRL_DTR_DSR ||
 	    cfg->flow_ctrl == UART_CFG_FLOW_CTRL_RS485) {
 		return -ENOSYS;

tests/drivers/uart/uart_elementary/boards/bgm220_ek4314a.overlay

@@ -0,0 +1,17 @@
+/*
+ * Copyright (c) 2025, Silicon Laboratories Inc.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/*
+ * Need to connect PB1 (L7) and PB2(L8) of the MikroE connector
+ */
+
+dut: &euart0 {
+	compatible = "silabs,eusart-uart";
+	pinctrl-0 = <&euart0_default>;
+	pinctrl-names = "default";
+	current-speed = <115200>;
+	status = "okay";
+};

tests/drivers/uart/uart_elementary/testcase.yaml

@@ -25,6 +25,7 @@ tests:
       - esp32h2_devkitm
       - esp32s2_saola
       - esp32s3_devkitm/esp32s3/procpu
+      - bgm220_ek4314a
       - xg24_rb4187c
       - bg29_rb4420a
       - xg29_rb4412a