Source Code Structure

The source code of USB driver is in the drivers/usb directory.

The following code blocks show the source code of the USB driver.

USB Host

The following list shows the source code of the USB driver in host mode.

For USB on the core level:

drivers/usb/core
├── Makefile
├── usb.c
├── hub.c
├── hcd.c
├── urb.c
├── message.c
├── driver.c
├── config.c
├── file.c
├── buffer.c
├── sysfs.c
├── endpoint.c
├── devio.c
├── notify.c
├── generic.c
├── quirks.c
├── devices.c
├── phy.c
├── port.c
├── of.c
├── hcd-pci.c
├── usb-acpi.c
├── Kconfig

For Xhci-host:

drivers/usb/host/
├── Makefile
├── Kconfig
├── xhci.c
├── xhci-plat.c
├── xhci-mem.c
├── xhci-ext-caps.c
├── xhci-ring.c
├── xhci-hub.c
├── xhci-dbg.c
├── xhci-trace.c
├── xhci-pci.c
├── xhci-debugfs.c

For CDNS3 on the core and role level:

drivers/usb/cdns3/
├── Makefile
├── core.c
├── drd.c
├── Kconfig

For CDNS3 on the platform level:

drivers/usb/cdns3/
├── cdns3-plat.c
├── cdns3-starfive.c

For CDN3 host:
```
drivers/usb/cdn3/
├── host.c
```

USB Device

The following list shows the source code of the USB driver in device mode.

For USB gadget driver:

drivers/usb/gadget/
├── usbstring.c
├── config.c
├── epautoconf.c
├── composite.c
├── functions.c
├── configfs.c
├── u_f.c
├── Makefile
├── Kconfig

For USB device function (mass storage and functionfs):

drivers/usb/gadget/function/
├── f_mass_storage.c
├── storage_common.c
├── f_fs.c
├── Makefile
├── Kconfig

For USB UDC driver:

drivers/usb/gadget/udc/
├── core.c
├── trace.c
├── Makefile
├── Kconfig

For CDN3 USB device driver:

For Linux 5.15:

drivers/usb/cdn3/
├── cdns3-gadget.c
├── cdns3-ep0.c

For Linux 5.10:

drivers/usb/cdn3/
├── gadget.c
├── ep0.c