From 731f8d473610f04ec3d0cf53cb10dd373b467f31 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Stenberg?= <bjorn@haxx.se>
Date: Thu, 8 Feb 2024 15:47:32 +0100
Subject: [PATCH] modbus: Respect CONFIG_UART_USE_RUNTIME_CONFIGURE
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Only perform runtime UART configuration if it is enabled.

Signed-off-by: Björn Stenberg <bjorn@haxx.se>
---
 subsys/modbus/Kconfig         |  2 +-
 subsys/modbus/modbus_serial.c | 94 ++++++++++++++++++++---------------
 2 files changed, 55 insertions(+), 41 deletions(-)

diff --git a/subsys/modbus/Kconfig b/subsys/modbus/Kconfig
index 38c7d761c076eb..4c49d6c0985194 100644
--- a/subsys/modbus/Kconfig
+++ b/subsys/modbus/Kconfig
@@ -44,7 +44,7 @@ config MODBUS_SERIAL
 	default y
 	depends on SERIAL && SERIAL_HAS_DRIVER
 	depends on DT_HAS_ZEPHYR_MODBUS_SERIAL_ENABLED
-	select UART_USE_RUNTIME_CONFIGURE
+	imply UART_USE_RUNTIME_CONFIGURE
 	help
 	  Enable Modbus over serial line support.
 
diff --git a/subsys/modbus/modbus_serial.c b/subsys/modbus/modbus_serial.c
index a8b65291781658..13d59c8154a193 100644
--- a/subsys/modbus/modbus_serial.c
+++ b/subsys/modbus/modbus_serial.c
@@ -444,6 +444,58 @@ static int configure_gpio(struct modbus_context *ctx)
 	return 0;
 }
 
+static inline int configure_uart(struct modbus_context *ctx,
+				 struct modbus_iface_param *param)
+{
+	struct modbus_serial_config *cfg = ctx->cfg;
+	struct uart_config uart_cfg = {
+		.baudrate = param->serial.baud,
+		.flow_ctrl = UART_CFG_FLOW_CTRL_NONE,
+	};
+
+	if (ctx->mode == MODBUS_MODE_ASCII) {
+		uart_cfg.data_bits = UART_CFG_DATA_BITS_7;
+	} else {
+		uart_cfg.data_bits = UART_CFG_DATA_BITS_8;
+	}
+
+	switch (param->serial.parity) {
+	case UART_CFG_PARITY_ODD:
+	case UART_CFG_PARITY_EVEN:
+		uart_cfg.parity = param->serial.parity;
+		uart_cfg.stop_bits = UART_CFG_STOP_BITS_1;
+		break;
+	case UART_CFG_PARITY_NONE:
+		/* Use of no parity requires 2 stop bits */
+		uart_cfg.parity = param->serial.parity;
+		uart_cfg.stop_bits = UART_CFG_STOP_BITS_2;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	if (ctx->client) {
+		/* Allow custom stop bit settings only in client mode */
+		switch (param->serial.stop_bits_client) {
+		case UART_CFG_STOP_BITS_0_5:
+		case UART_CFG_STOP_BITS_1:
+		case UART_CFG_STOP_BITS_1_5:
+		case UART_CFG_STOP_BITS_2:
+			uart_cfg.stop_bits = param->serial.stop_bits_client;
+			break;
+		default:
+			return -EINVAL;
+		}
+	}
+
+	if (uart_configure(cfg->dev, &uart_cfg) != 0) {
+		LOG_ERR("Failed to configure UART");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 void modbus_serial_rx_disable(struct modbus_context *ctx)
 {
 	modbus_serial_rx_off(ctx);
@@ -505,7 +557,6 @@ int modbus_serial_init(struct modbus_context *ctx,
 	struct modbus_serial_config *cfg = ctx->cfg;
 	const uint32_t if_delay_max = 3500000;
 	const uint32_t numof_bits = 11;
-	struct uart_config uart_cfg;
 
 	switch (param.mode) {
 	case MODBUS_MODE_RTU:
@@ -521,49 +572,12 @@ int modbus_serial_init(struct modbus_context *ctx,
 		return -ENODEV;
 	}
 
-	uart_cfg.baudrate = param.serial.baud,
-	uart_cfg.flow_ctrl = UART_CFG_FLOW_CTRL_NONE;
-
-	if (ctx->mode == MODBUS_MODE_ASCII) {
-		uart_cfg.data_bits = UART_CFG_DATA_BITS_7;
-	} else {
-		uart_cfg.data_bits = UART_CFG_DATA_BITS_8;
-	}
-
-	switch (param.serial.parity) {
-	case UART_CFG_PARITY_ODD:
-	case UART_CFG_PARITY_EVEN:
-		uart_cfg.parity = param.serial.parity;
-		uart_cfg.stop_bits = UART_CFG_STOP_BITS_1;
-		break;
-	case UART_CFG_PARITY_NONE:
-		/* Use of no parity requires 2 stop bits */
-		uart_cfg.parity = param.serial.parity;
-		uart_cfg.stop_bits = UART_CFG_STOP_BITS_2;
-		break;
-	default:
-		return -EINVAL;
-	}
-
-	if (ctx->client) {
-		/* Allow custom stop bit settings only in client mode */
-		switch (param.serial.stop_bits_client) {
-		case UART_CFG_STOP_BITS_0_5:
-		case UART_CFG_STOP_BITS_1:
-		case UART_CFG_STOP_BITS_1_5:
-		case UART_CFG_STOP_BITS_2:
-			uart_cfg.stop_bits = param.serial.stop_bits_client;
-			break;
-		default:
+	if (IS_ENABLED(CONFIG_UART_USE_RUNTIME_CONFIGURE)) {
+		if (configure_uart(ctx, &param) != 0) {
 			return -EINVAL;
 		}
 	}
 
-	if (uart_configure(cfg->dev, &uart_cfg) != 0) {
-		LOG_ERR("Failed to configure UART");
-		return -EINVAL;
-	}
-
 	if (param.serial.baud <= 38400) {
 		cfg->rtu_timeout = (numof_bits * if_delay_max) /
 				   param.serial.baud;