boards: add common configuration for CDC ACM UART

Many boards have similar code to configure the USB and CDC ACM UART that
they want to use as a logging or shell backend. Some of them have an
incorrect or incomplete configuration.

These boards do not have a built-in debug adapter, but a SoC with a USB
device controller and a bootloader with USB device support. Introduce
common CDC ACM UART configuration that these boards should use for
logging or shell backend to avoid duplicate or incorrect configuration.

Signed-off-by: Johann Fischer <johann.fischer@nordicsemi.no>

boards/Kconfig

@@ -128,6 +128,20 @@ config QEMU_EXTRA_FLAGS
 	  to setup devices, for example to allocate interface for Zephyr
 	  GDBstub over serial with `-serial tcp:127.0.0.1:5678,server`
 
+config BOARD_REQUIRES_SERIAL_BACKEND_CDC_ACM
+	bool
+	help
+	  Indicates that a board has no other capabilities than to use the CDC
+	  ACM UART as a backend for logging or shell.
+
+config BOARD_SERIAL_BACKEND_CDC_ACM
+	bool "Board uses USB CDC ACM UART as serial backend"
+	depends on BOARD_REQUIRES_SERIAL_BACKEND_CDC_ACM
+	default y
+	help
+	  USB stack and CDC ACM UART are configured and initialized at boot
+	  time to be used as a backend for logging or shell.
+
 # There might not be any board options, hence the optional source
 osource "$(KCONFIG_BOARD_DIR)/Kconfig"
 endmenu

boards/common/usb/Kconfig.cdc_acm_serial.defconfig

@@ -0,0 +1,51 @@
+# Copyright (c) 2023-2024 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: Apache-2.0
+
+config BOARD_REQUIRES_SERIAL_BACKEND_CDC_ACM
+	default y
+
+if BOARD_SERIAL_BACKEND_CDC_ACM
+
+config SERIAL
+	default y
+
+config CONSOLE
+	default y
+
+config UART_CONSOLE
+	default CONSOLE
+
+config SHELL_BACKEND_SERIAL_CHECK_DTR
+	default SHELL
+	depends on UART_LINE_CTRL
+
+config UART_LINE_CTRL
+	default SHELL
+
+config USB_DEVICE_STACK
+	default y
+
+config USB_DEVICE_INITIALIZE_AT_BOOT
+	default y if !MCUBOOT
+
+config USB_DEVICE_REMOTE_WAKEUP
+	default n
+
+if LOG
+
+choice USB_CDC_ACM_LOG_LEVEL_CHOICE
+	default USB_CDC_ACM_LOG_LEVEL_OFF
+endchoice
+
+choice USB_DEVICE_LOG_LEVEL_CHOICE
+	default USB_DEVICE_LOG_LEVEL_OFF
+endchoice
+
+# Wait 4000ms at startup for logging
+config LOG_PROCESS_THREAD_STARTUP_DELAY_MS
+	default 4000
+
+endif # LOG
+
+endif # BOARD_SERIAL_BACKEND_CDC_ACM

boards/common/usb/cdc_acm_serial.dtsi

@@ -0,0 +1,21 @@
+/*
+ * Copyright (c) 2024 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/ {
+	chosen {
+		zephyr,console = &board_cdc_acm_uart;
+		zephyr,shell-uart = &board_cdc_acm_uart;
+		zephyr,uart-mcumgr = &board_cdc_acm_uart;
+		zephyr,bt-mon-uart = &board_cdc_acm_uart;
+		zephyr,bt-c2h-uart = &board_cdc_acm_uart;
+	};
+};
+
+&zephyr_udc0 {
+	board_cdc_acm_uart: board_cdc_acm_uart {
+		compatible = "zephyr,cdc-acm-uart";
+	};
+};