reflect bitrate change of uart in uart struct

stm-firmware/include/stm-periph/uart.h

@@ -48,6 +48,8 @@ struct stm_uart {
 
 int uart_init(struct stm_uart *uart);
 
+void uart_change_brr(struct stm_uart *uart, uint32_t brr);
+
 void uart_disable(struct stm_uart *uart);
 
 void uart_send_char(struct stm_uart *uart, char c);

stm-firmware/stm-periph/uart.c

@@ -86,6 +86,15 @@ int uart_init(struct stm_uart *uart)
 	return 0;
 }
 
+void uart_change_brr(struct stm_uart *uart, uint32_t brr)
+{
+	if (!uart || !uart->uart_dev)
+		return;
+
+	uart->brr_val = brr;
+	uart->uart_dev->BRR = brr;
+}
+
 void uart_disable(struct stm_uart *uart)
 {
 	if (!uart)