usb: patches to resolve issues around Kconfig option USB_UART_CONSOLE

boards/shields/cdc_acm/Kconfig.defconfig

@@ -0,0 +1,43 @@
+# Copyright (c) 2021 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+
+if SHIELD_CDC_ACM_CONSOLE || SHIELD_CDC_ACM_SHELL
+
+# TEST_LOGGING_DEFAULTS option sets all log levels to INF,
+# including the USB_CDC_ACM_LOG_LEVEL and that can not work.
+config TEST_LOGGING_DEFAULTS
+	default n
+
+config SERIAL
+	default y
+
+config UART_LINE_CTRL
+	default y
+
+config USB_DEVICE_STACK
+	default y
+
+config USB_DEVICE_INITIALIZE_AT_BOOT
+	default y
+
+endif #if SHIELD_CDC_ACM_CONSOLE || SHIELD_CDC_ACM_SHELL
+
+if SHIELD_CDC_ACM_CONSOLE
+
+config CONSOLE
+	default y
+
+config UART_CONSOLE
+	default y
+
+endif #if SHIELD_CDC_ACM_CONSOLE
+
+if SHIELD_CDC_ACM_SHELL
+
+config SHELL_BACKEND_SERIAL_CHECK_DTR
+	default y
+
+config LOG_PRINTK
+	default y
+
+endif #if SHIELD_CDC_ACM_SHELL

boards/shields/cdc_acm/Kconfig.shield

@@ -0,0 +1,8 @@
+# Copyright (c) 2021
+# SPDX-License-Identifier: Apache-2.0
+
+config SHIELD_CDC_ACM_CONSOLE
+	def_bool $(shields_list_contains,cdc_acm_console)
+
+config SHIELD_CDC_ACM_SHELL
+	def_bool $(shields_list_contains,cdc_acm_shell)

boards/shields/cdc_acm/cdc_acm_console.overlay

@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2021 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/ {
+	chosen {
+		zephyr,console = &console_cdc_acm_uart0;
+	};
+};
+
+&zephyr_udc0 {
+	console_cdc_acm_uart0: console_cdc_acm_uart0 {
+		compatible = "zephyr,cdc-acm-uart";
+		label = "CONSOLE_CDC_ACM_0";
+	};
+};

boards/shields/cdc_acm/cdc_acm_shell.overlay

@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2021 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/ {
+	chosen {
+		zephyr,shell-uart = &shell_cdc_acm_uart0;
+	};
+};
+
+&zephyr_udc0 {
+	shell_cdc_acm_uart0: shell_cdc_acm_uart0 {
+		compatible = "zephyr,cdc-acm-uart";
+		label = "SHELL_CDC_ACM_0";
+	};
+};

boards/shields/cdc_acm/doc/index.rst

@@ -0,0 +1,64 @@
+.. _cdc_acm_shield:
+
+Generic shields for CDC ACM UART
+################################
+
+Overview
+********
+
+This is a generic shield that provides devicetree and configuration overlays,
+and configures USB device stack so that CDC ACM UART can be used as backend
+for console, logging, and shell. It is mainly intended to be used with boards
+that do not have a debug adapter or native UART, but do have a USB device
+controller.
+This approach allows us to avoid many identical overlays in samples and tests
+directories (see :ref:`usb_device_cdc_acm` for more details).
+It also simplifies the configuration of the above mentioned boards,
+they can stay with the minimal configuration which minimizes the conflicts
+especially with different in-tree samples.
+
+These shields enable :kconfig:`CONFIG_USB_DEVICE_INITIALIZE_AT_BOOT` and
+configure USB device stack so that it is automatically initialized.
+This is important for the boards like :ref:`nrf52840dongle_nrf52840`,
+otherwise in-tree samples, that do not enable USB device support, are
+not usable. But it also means that in-tree samples, like :ref:`usb_cdc-acm`,
+that initialize USB device support themselves cannot be used with these shields.
+This is a good compromise which provides maximum coverage of usable samples for
+these specific USB dongles.
+
+Current supported chosen properties
+===================================
+
++-----------------------+---------------------+
+| Chosen property       | Shield Designation  |
+|                       |                     |
++=======================+=====================+
+| ``zephyr,console``    | ``cdc_acm_console`` |
++-----------------------+---------------------+
+| ``zephyr,shell-uart`` | ``cdc_acm_shell``   |
++-----------------------+---------------------+
+
+Requirements
+************
+
+This shield can only be used with a board which provides a USB device
+controller.
+
+Programming
+***********
+
+Set ``-DSHIELD=cdc_acm_shell`` when you invoke ``west build``. For example:
+
+.. zephyr-app-commands::
+   :zephyr-app: samples/subsys/shell/shell_module
+   :board: nrf52840dongle_nrf52840
+   :shield: cdc_acm_shell
+   :goals: build
+
+Or ``-DSHIELD=cdc_acm_console``, for example:
+
+.. zephyr-app-commands::
+   :zephyr-app: samples/basic/threads
+   :board: nrf52840dongle_nrf52840
+   :shield: cdc_acm_console
+   :goals: build

doc/reference/usb/uds_cdc_acm.rst

@@ -106,3 +106,7 @@ CDC ACM UART as backend for a subsystem or application:
 * ``zephyr,shell-uart`` used by shell for serial backend,
   for example see :zephyr_file:`samples/subsys/shell/shell_module`
 * ``zephyr,uart-mcumgr`` used by :ref:`smp_svr_sample`
+
+In-tree samples that do not require any USB device classes other than
+CDC ACM UART for console, logging, or shell should be built with
+:ref:`cdc_acm_shield`.