drivers: serial: stm32: return error for bad baud

[edenfrosst]

The uart_stm32 driver gives no way for a user to tell if setting a new baud rate was successful.
Propagate error checks up to the API level.

[github-actions]

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[Copilot]

Pull Request Overview

This PR updates the STM32 serial driver to propagate errors when setting the baud rate, ensuring the API reflects possible failures during configuration.

• Change uart_stm32_set_baudrate and uart_stm32_parameters_set to return error codes.
• Propagate error checks in uart_stm32_configure and uart_stm32_registers_configure.
• Update return statements to provide specific error codes for failure cases.

Comments suppressed due to low confidence (2)

drivers/serial/uart_stm32.c:184

• The error code returned when the baud rate prescaler index is out of range differs from the error code used in uart_stm32_configure (-ENOTSUP) and uart_stm32_registers_configure (-EINVAL). Consider standardizing the error codes returned across functions for a more consistent API.

			return -EINVAL;

drivers/serial/uart_stm32.c:491

• Since the return type of uart_stm32_parameters_set has been changed from void to int for error propagation, ensure that the function's documentation (comments or API docs) is updated to reflect this change.

static int uart_stm32_parameters_set(const struct device *dev,

[etienne-lms]

Some minor comment and a free question.
Otherwise LGTM.

[etienne-lms]

LGTM.

Maybe could you fix the commit message header line:

-drivers: serial: stm32: return error for bad baud
+drivers: serial: stm32: return error for bad baud rate

or

drivers: serial: stm32: propagate baud rate config failure

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud