portentah7: add log uart

uart will be used by loader for logging when SHELL is not enabled

Author: pennam

variants/arduino_portenta_h7_stm32h747xx_m7/arduino_portenta_h7_stm32h747xx_m7.conf

@@ -3,9 +3,10 @@ CONFIG_USB_DEVICE_PRODUCT="Arduino Portenta H7"
 CONFIG_USB_DEVICE_MANUFACTURER="Arduino"
 CONFIG_USB_DEVICE_VID=0x2341
 CONFIG_USB_DEVICE_PID=0x005b
+CONFIG_USB_DEVICE_INITIALIZE_AT_BOOT=n
 
 CONFIG_USB_CDC_ACM=y
-CONFIG_USB_CDC_ACM_RINGBUF_SIZE=512
+CONFIG_USB_CDC_ACM_RINGBUF_SIZE=1024
 CONFIG_UART_LINE_CTRL=y
 CONFIG_CDC_ACM_DTE_RATE_CALLBACK_SUPPORT=y
 
@@ -17,6 +18,10 @@ CONFIG_COMMON_LIBC_MALLOC_ARENA_SIZE=-1
 CONFIG_CPP=n
 CONFIG_SHELL=n
 
+CONFIG_LOG_BACKEND_UART=y
+CONFIG_LOG_BACKEND_UART_AUTOSTART=n
+CONFIG_LOG_DEFAULT_LEVEL=2
+
 CONFIG_FPU=y
 CONFIG_ICACHE=y
 CONFIG_DCACHE=y

variants/arduino_portenta_h7_stm32h747xx_m7/arduino_portenta_h7_stm32h747xx_m7.overlay

@@ -248,6 +248,12 @@
 		zephyr,console = &usart6;
 		zephyr,shell-uart = &usart6;
 		zephyr,cdc-acm-uart0 = &usart6;
+		zephyr,log-uart = &log_uarts;
+	};
+
+	log_uarts: log_uarts {
+		compatible = "zephyr,log-uart";
+		uarts = <&usart6 &board_cdc_acm_uart>;
 	};
 
 	/* used to overcome problems with _C analog pins */