boards/arduino/portenta_h7: enable USART1 on M4

Right now, USART1 is enabled on the M7 target variant by default, leaving
M4 without a UART to use; this is the way this port was originally
contributed.

Since then, USB was enabled on M7, changing the console backend from USART1
to USB CDC ACM; the M4 target was left unchanged.

This commit enabled USART1 on the M4 variant and disabled it on the M7
variant, so that the M4 variant can use it as its console backend.

Note that, for the M4 variant, USART1 has been assigned to `zephyr,console`
and `zephyr,shell-uart` since this port was contributed, even though USART1
was always disabled on M4.

Signed-off-by: Filip Kokosinski <[email protected]>

Author: fkokosinski

boards/arduino/portenta_h7/arduino_portenta_h7_stm32h747xx_m4.dts

@@ -28,5 +28,5 @@
 };
 
 &usart1 {
-	status = "disabled";
+	status = "okay";
 };

boards/arduino/portenta_h7/arduino_portenta_h7_stm32h747xx_m4_defconfig

@@ -10,9 +10,7 @@ CONFIG_ARM_MPU=y
 # Enable HW stack protection
 CONFIG_HW_STACK_PROTECTION=y
 
-# Enable uart driver
-# CONFIG_SERIAL=y
-
-# By default CONSOLE is assigned to m7
-# CONFIG_CONSOLE=y
-# CONFIG_UART_CONSOLE=y
+# On M4, USART1 is used as the UART console backend by default
+CONFIG_SERIAL=y
+CONFIG_CONSOLE=y
+CONFIG_UART_CONSOLE=y

boards/arduino/portenta_h7/arduino_portenta_h7_stm32h747xx_m7.dts

@@ -80,9 +80,9 @@
 	clock-frequency = <DT_FREQ_M(400)>;
 };
 
-
+/* USART1 is enabled on M4 by default */
 &usart1 {
-	status = "okay";
+	status = "disabled";
 };
 
 &i2c1 {

boards/arduino/portenta_h7/arduino_portenta_h7_stm32h747xx_m7_defconfig

@@ -16,12 +16,8 @@ CONFIG_HW_STACK_PROTECTION=y
 # Use zephyr,code-partition as flash offset
 CONFIG_USE_DT_CODE_PARTITION=y
 
-# Disable following to assign serial ports to m4 core
-
-# Enable uart driver
+# On M7, USB CDC ACM is used as the UART console backend by default
 CONFIG_SERIAL=y
-
-# Enable console
 CONFIG_CONSOLE=y
 CONFIG_UART_CONSOLE=y
 CONFIG_UART_LINE_CTRL=y