Add Kernel Module Configuration for USB Gadget

[mihai-chiorean]

Description

USB gadget requires specific kernel modules that may not be enabled by default. Need to ensure they're built and loaded.

Required Kernel Modules

CONFIG_USB_CONFIGFS=m
CONFIG_USB_LIBCOMPOSITE=m
CONFIG_USB_F_NCM=m
CONFIG_USB_F_ECM=m
CONFIG_USB_F_RNDIS=m
CONFIG_USB_GADGET=y
CONFIG_USB_DWC2=m
CONFIG_USB_DWC2_DUAL_ROLE=y

Implementation Approaches

1. Kernel Config Fragment

Create meta-edgeos/recipes-kernel/linux/linux-raspberrypi/usb-gadget.cfg:

CONFIG_USB_CONFIGFS=m
CONFIG_USB_LIBCOMPOSITE=m
CONFIG_USB_F_NCM=m
CONFIG_USB_F_ECM=m
CONFIG_USB_F_RNDIS=m
CONFIG_USB_F_EEM=m
CONFIG_USB_F_SUBSET=m
CONFIG_USB_GADGET=y
CONFIG_USB_GADGET_VBUS_DRAW=500
CONFIG_USB_DWC2=m
CONFIG_USB_DWC2_DUAL_ROLE=y

2. Kernel Recipe bbappend

# linux-raspberrypi_%.bbappend
FILESEXTRAPATHS:prepend := "${THISDIR}/${PN}:"
SRC_URI += "file://usb-gadget.cfg"

3. Update Package Group

# packagegroup-edgeos-kernel.bb
RDEPENDS:${PN} = " \
    kernel-module-libcomposite \
    kernel-module-usb-f-ncm \
    kernel-module-usb-f-ecm \
    kernel-module-usb-f-rndis \
    kernel-module-dwc2 \
    "

4. Module Loading Configuration

# /etc/modules-load.d/usb-gadget.conf
dwc2
libcomposite

Acceptance Criteria

• All required modules built as part of kernel
• Modules auto-load at boot
• libcomposite loads before gadget setup
• Works without manual modprobe
• Module dependencies handled correctly
• Configuration works for both RPi 4 and RPi 5