tests: drivers: uart stm32 run uart_async api on f746 nucleo

This sets the dts of dma for using the uart 6 asynch api.
The stm32f746 has a dma V1 with request 5 for Tx/Rx usart6
The Tx&Rx pins (PG14, PG9) of the usart6 are connected
on the nucleo_f746zg board to pass the test
The CONFIG_DCACHE=n must also be set to disable Dcache.

Signed-off-by: Francois Ramu <[email protected]>

Author: FRASTM

tests/drivers/uart/uart_async_api/boards/nucleo_f746zg.conf

@@ -0,0 +1 @@
+CONFIG_DCACHE=n

tests/drivers/uart/uart_async_api/boards/nucleo_f746zg.overlay

@@ -0,0 +1,12 @@
+/* SPDX-License-Identifier: Apache-2.0 */
+
+&usart6 {
+	dmas = <&dma2 7 5 0x28440 0x03>,
+		<&dma2 2 5 0x28480 0x03>;
+	dma-names = "tx", "rx";
+	status = "okay";
+};
+
+&dma2 {
+	status = "okay";
+};

tests/drivers/uart/uart_async_api/src/test_uart.h

@@ -47,7 +47,8 @@
 #define UART_DEVICE_NAME DT_LABEL(DT_NODELABEL(uart4))
 #elif defined(CONFIG_BOARD_NUCLEO_F429ZI) || \
 	defined(CONFIG_BOARD_NUCLEO_F207ZG) || \
-	defined(CONFIG_BOARD_NUCLEO_F767ZI)
+	defined(CONFIG_BOARD_NUCLEO_F767ZI) || \
+	defined(CONFIG_BOARD_NUCLEO_F746ZG)
 #define UART_DEVICE_NAME DT_LABEL(DT_NODELABEL(usart6))
 #elif defined(CONFIG_BOARD_FRDM_K82F)
 #define UART_DEVICE_NAME DT_LABEL(DT_NODELABEL(lpuart0))