Updated: 2022/Sep/29

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USB(4)                       Device Drivers Manual                      USB(4)

     usb - Universal Serial Bus driver

     ehci*   at cardbus? function ?
     ehci*   at pci? dev ? function ?
     ohci*   at cardbus? function ?
     ohci*   at pci? dev ? function ?
     xhci*   at pci? dev ? function ?
     slhci*  at isa? port ? irq ?
     slhci*  at pcmcia? function ?
     uhci*   at cardbus? function ?
     uhci*   at pci? dev ? function ?
     usb*    at ehci?
     usb*    at ohci?
     usb*    at uhci?
     usb*    at slhci?
     uhub*   at usb?
     uhub*   at uhub? port ? configuration ? interface ? vendor ? product ?
     release ?
     XX*     at uhub? port ? configuration ? interface ? vendor ? product ?
     release ?

     options USBVERBOSE

     #include <dev/usb/usb.h>
     #include <dev/usb/usbhid.h>

     NetBSD provides machine-independent bus support and drivers for USB

     The NetBSD usb driver has three layers (like scsi(4) and pcmcia(4)): the
     controller, the bus, and the device layer.  The controller attaches to a
     physical bus (like pci(4)).  The USB bus attaches to the controller and
     the root hub attaches to the bus.  Further devices, which may include
     further hubs, attach to other hubs.  The attachment forms the same tree
     structure as the physical USB device tree.  For each USB device there may
     be additional drivers attached to it.

     The uhub device controls USB hubs and must always be present since there
     is at least a root hub in any USB system.

     NetBSD supports the following machine-independent USB drivers:

   Storage devices
        umass(4)      USB Mass Storage Devices, e.g., external disk drives

   Wired network interfaces
        aue(4)        ADMtek AN986/ADM8511 Pegasus family 10/100 USB Ethernet
        axe(4)        ASIX Electronics AX88172/AX88178/AX88772 10/100/Gigabit
                      USB Ethernet device
        axen(4)       ASIX Electronics AX88178a/AX88179 10/100/Gigabit USB
                      Ethernet device
        cdce(4)       USB Communication Device Class Ethernet device
        cue(4)        CATC USB-EL1201A USB Ethernet device
        kue(4)        Kawasaki LSI KL5KUSB101B USB Ethernet device
        mos(4)        MosChip MCS7730/7830/7832 10/100 USB Ethernet device
        mue(4)        Microchip LAN75xx/LAN78xx 10/100/Gigabit USB Ethernet
        udav(4)       Davicom DM9601 10/100 USB Ethernet device
        ure(4)        Realtek RTL8152/RTL8153 10/100/Gigabit USB Ethernet
        url(4)        Realtek RTL8150L 10/100 USB Ethernet device
        urndis(4)     USB Remote NDIS Ethernet device
        usmsc(4)      SMSC LAN95xx 10/100 USB Ethernet device

   Wireless network interfaces
        atu(4)        Atmel AT76C50x IEEE 802.11b wireless network device
        ral(4)        Ralink Technology USB IEEE 802.11b/g wireless network
        rum(4)        Ralink Technology USB IEEE 802.11a/b/g wireless network
        run(4)        Ralink Technology USB IEEE 802.11a/b/g/n wireless
                      network device
        ubt(4)        USB Bluetooth dongles
        upgt(4)       Conexant/Intersil PrismGT SoftMAC USB 802.11b/g wireless
                      network device
        urtwn(4)      Realtek RTL8188CU/RTL8192CU USB IEEE 802.11b/g/n
                      wireless network device
        zyd(4)        ZyDAS ZD1211/ZD1211B USB IEEE 802.11b/g wireless network

   Serial and parallel interfaces
        uark(4)       Arkmicro Technologies ARK3116 based USB serial adapters
        ubsa(4)       Belkin USB serial adapter
        uchcom(4)     WinChipHead CH341/340 based USB serial adapter
        ucom(4)       USB tty support
        ucycom(4)     Cypress microcontroller based USB serial adapter
        uftdi(4)      FT8U100AX USB serial adapter
        ugensa(4)     USB generic serial adapter
        uipaq(4)      iPAQ USB units
        ukyopon(4)    USB Kyocera AIR-EDGE PHONE device
        ulpt(4)       USB printer support
        umct(4)       MCT USB-RS232 USB serial adapter
        umodem(4)     USB modem support
        uplcom(4)     Prolific PL-2303 USB serial adapter
        uslsa(4)      Silicon Laboratories CP2101/CP2102 based USB serial
        uvisor(4)     USB Handspring Visor
        uvscom(4)     SUNTAC Slipper U VS-10U USB serial adapter
        uxrcom(4)     Exar XR21V141x USB serial adapter

   Cellular WAN interfaces
        u3g(4)        USB 3G modems
        uhmodem(4)    Huawei 3G wireless modems
        uhso(4)       Option N.V. Wireless WAN modems
        umb(4)        USB Mobile Broadband Interface Model (MBIM) devices

   Audio devices
        uaudio(4)     USB audio devices
        umidi(4)      USB MIDI devices

   Radio receiver devices
        slurm(4)      Silicon Labs USB FM radios
        udsbr(4)      D-Link DSB-R100 USB radio device

   Human Interface Devices
        uatp(4)       Apple trackpads
        uep(4)        eGalax touch panel controllers
        uhid(4)       Generic driver for Human Interface Devices
        uhidev(4)     Base driver for all Human Interface Devices
        uintuos(4)    Wacom Intuos drawing tablets
        ukbd(4)       USB keyboards that follow the boot protocol
        ums(4)        USB mouse devices
        uthum(4)      TEMPer and TEMPerHUM temperature and humidity sensors
        uts(4)        Generic driver for touchscreens and touch digitizers

   Miscellaneous devices
        stuirda(4)    Sigmaltel 4116/4220 USB-IrDA bridge
        ualea(4)      USB Araneus Alea I/II random number generators
        uberry(4)     Battery charging RIM BlackBerry phones via USB
        udl(4)        DisplayLink DL-1x0/1x5 USB display devices
        ugen(4)       USB generic devices
        uipad(4)      Battery charging iOS devices via USB
        uirda(4)      USB IrDA bridges
        upl(4)        Prolific based host-to-host adapters
        usscanner(4)  SCSI-over-USB scanners
        ustir(4)      SigmaTel STIr4200 USB IrDA bridges
        utoppy(4)     Topfield TF5000PVR range of digital video recorders

     The USB 1.x is a 12 Mb/s serial bus with 1.5 Mb/s for low speed devices.
     USB 2.x handles 480 Mb/s.  Each USB has a host controller that is the
     master of the bus; all other devices on the bus only speak when spoken

     There can be up to 127 devices (apart from the host controller) on a bus,
     each with its own address.  The addresses are assigned dynamically by the
     host when each device is attached to the bus.

     Within each device there can be up to 16 endpoints.  Each endpoint is
     individually addressed and the addresses are static.  Each of these
     endpoints will communicate in one of four different modes: control,
     isochronous, bulk, or interrupt.  A device always has at least one
     endpoint.  This endpoint has address 0 and is a control endpoint and is
     used to give commands to and extract basic data, such as descriptors,
     from the device.  Each endpoint, except the control endpoint, is

     The endpoints in a device are grouped into interfaces.  An interface is a
     logical unit within a device; e.g., a compound device with both a
     keyboard and a trackball would present one interface for each.  An
     interface can sometimes be set into different modes, called alternate
     settings, which affects how it operates.  Different alternate settings
     can have different endpoints within it.

     A device may operate in different configurations.  Depending on the
     configuration the device may present different sets of endpoints and

     Each device located on a hub has several config(1) locators:
     port       this is the number of the port on closest upstream hub.
                this is the configuration the device must be in for this
                driver to attach.  This locator does not set the
                configuration; it is iterated by the bus enumeration.
     interface  this is the interface number within a device that an interface
                driver attaches to.
     vendor     this is the 16 bit vendor id of the device.
     product    this is the 16 bit product id of the device.
     release    this is the 16 bit release (revision) number of the device.
     The first locator can be used to pin down a particular device according
     to its physical position in the device tree.  The last three locators can
     be used to pin down a particular device according to what device it
     actually is.

     The bus enumeration of the USB bus proceeds in several steps:

     1.   Any device specific driver can attach to the device.

     2.   If none is found, any device class specific driver can attach.

     3.   If none is found, all configurations are iterated over.  For each
          configuration all the interface are iterated over and interface
          drivers can attach.  If any interface driver attached in a certain
          configuration the iteration over configurations is stopped.

     4.   If still no drivers have been found, the generic USB driver can

     Use the following to get access to the USB specific structures and

     #include <dev/usb/usb.h>

     The /dev/usbN can be opened and a few operations can be performed on it.
     The poll(2) system call will say that I/O is possible on the controller
     device when a USB device has been connected or disconnected to the bus.

     The following ioctl(2) commands are supported on the controller device:

     USB_DEVICEINFO struct usb_device_info
             This command can be used to retrieve some information about a
             device on the bus.  The addr field should be filled before the
             call and the other fields will be filled by information about the
             device on that address.  Should no such device exist an error is

             struct usb_device_info {
                     uint8_t udi_bus;
                     uint8_t udi_addr;
                     usb_event_cookie_t udi_cookie;
                     char            udi_product[USB_MAX_ENCODED_STRING_LEN];
                     char            udi_vendor[USB_MAX_ENCODED_STRING_LEN];
                     char            udi_release[8];
                     char            udi_serial[USB_MAX_ENCODED_STRING_LEN];
                     uint16_t        udi_productNo;
                     uint16_t        udi_vendorNo;
                     uint16_t        udi_releaseNo;
                     uint8_t udi_class;
                     uint8_t udi_subclass;
                     uint8_t udi_protocol;
                     uint8_t udi_config;
                     uint8_t udi_speed;
             #define USB_SPEED_LOW  1
             #define USB_SPEED_FULL 2
             #define USB_SPEED_HIGH 3
                     int             udi_power;
                     int             udi_nports;
                     char            udi_devnames[USB_MAX_DEVNAMES][USB_MAX_DEVNAMELEN];
                     uint8_t udi_ports[16];
             #define USB_PORT_ENABLED 0xff
             #define USB_PORT_SUSPENDED 0xfe
             #define USB_PORT_POWERED 0xfd
             #define USB_PORT_DISABLED 0xfc

             The product, vendor, release, and serial fields contain self-
             explanatory descriptions of the device.

             The class field contains the device class.

             The config field shows the current configuration of the device.

             The lowspeed field is set if the device is a USB low speed

             The power field shows the power consumption in milli-amps drawn
             at 5 volts, or zero if the device is self powered.

             If the device is a hub the nports field is non-zero and the ports
             field contains the addresses of the connected devices.  If no
             device is connected to a port one of the USB_PORT_* values
             indicates its status.

     USB_DEVICESTATS struct usb_device_stats
             This command retrieves statistics about the controller.

             struct usb_device_stats {
                     u_long  uds_requests[4];

             The requests field is indexed by the transfer kind, i.e.  UE_*,
             and indicates how many transfers of each kind have been completed
             by the controller.

     USB_REQUEST struct usb_ctl_request
             This command can be used to execute arbitrary requests on the
             control pipe.  This is DANGEROUS and should be used with great
             care since it can destroy the bus integrity.

     The include file <dev/usb/usb.h> contains definitions for the types used
     by the various ioctl(2) calls.  The naming convention of the fields for
     the various USB descriptors exactly follows the naming in the USB
     specification.  Byte sized fields can be accessed directly, but word (16
     bit) sized fields must be access by the UGETW(field) and USETW(field,
     value) macros to handle byte order and alignment properly.

     The include file <dev/usb/usbhid.h> similarly contains the definitions
     for Human Interface Devices (HID).

     All USB events are reported via the /dev/usb device.  This devices can be
     opened for reading and each read(2) will yield an event record (if
     something has happened).  The poll(2) system call can be used to
     determine if an event record is available for reading.

     The event record has the following definition:

     struct usb_event {
             int                                 ue_type;
             struct timespec                     ue_time;
             union {
                     struct {
                             int                 ue_bus;
                     } ue_ctrlr;
                     struct usb_device_info      ue_device;
                     struct {
                             usb_event_cookie_t  ue_cookie;
                             char                ue_devname[16];
                     } ue_driver;
             } u;

     The ue_type field identifies the type of event that is described.  The
     possible events are attach/detach of a host controller, a device, or a
     device driver.  The union contains information pertinent to the different
     types of events.

     The ue_bus contains the number of the USB bus for host controller events.

     The ue_device record contains information about the device in a device
     event event.

     The ue_cookie is an opaque value that uniquely determines which device a
     device driver has been attached to (i.e., it equals the cookie value in
     the device that the driver attached to).  The ue_devname contains the
     name of the device (driver) as seen in, e.g., kernel messages.

     Note that there is a separation between device and device driver events.
     A device event is generated when a physical USB device is attached or
     detached.  A single USB device may have zero, one, or many device drivers
     associated with it.

     For each USB bus, i.e., for each host controller, there is a kernel
     thread that handles attach and detach of devices on that bus.  The thread
     is named usbN where N is the bus number.

     In addition there is a kernel thread, usbtask, which handles various
     minor tasks that are initiated from an interrupt context, but need to
     sleep, e.g., time-out abort of transfers.

     usbhidaction(1), usbhidctl(1), cardbus(4), ehci(4), isa(4), ohci(4),
     pci(4), pcmcia(4), slhci(4), uhci(4), xhci(4), usbdevs(8)

     Universal Serial Bus Specifications Documents,

     The usb driver appeared in NetBSD 1.4.

     There should be a serial number locator, but NetBSD does not have string
     valued locators.

NetBSD 9.99                      July 10, 2022                     NetBSD 9.99