USB(4)                       Device Drivers Manual                      USB(4)


     usb, uhub - introduction to Universal Serial Bus support


     # octeon specific
     dwctwo0 at iobus? irq 56
     # all architectures
     ehci*   at cardbus?
     ohci*   at cardbus?
     uhci*   at cardbus?
     ehci*   at pci?
     ohci*   at pci?
     uhci*   at pci?
     xhci*   at pci?
     usb*    at dwctwo?
     usb*    at ehci? flags 0x00
     usb*    at ohci? flags 0x00
     usb*    at uhci? flags 0x00
     usb*    at xhci? flags 0x00
     uhub*   at usb?
     uhub*   at uhub?

     option    USBVERBOSE

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


     OpenBSD provides machine-independent bus support and drivers for
     Universal Serial Bus (USB) devices.

     The OpenBSD 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) or cardbus(4)).  The USB bus attaches to the
     controller and the root hub attaches to the USB bus.  Devices, which may
     include further hubs, attach to the root hub.  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 driver controls USB hubs and must always be present since there
     is at least one root hub in any USB system.

     The flags are used to specify if the devices on the USB bus should be
     probed early in the boot process.  If the flags are specified with a
     value of 1, the USB bus will be probed when the USB host device is
     attached instead of waiting until kernel processes start running.

     OpenBSD provides support for the following devices.  Note that not all
     architectures support all devices.

   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 AX88179 10/100/Gigabit USB Ethernet
        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
        smsc(4)       SMSC LAN95xx 10/100 USB Ethernet device
        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

   Wireless network interfaces
        athn(4)       Atheros IEEE 802.11a/b/g/n wireless network device
        atu(4)        Atmel AT76C50x IEEE 802.11b wireless network device
        otus(4)       Atheros USB IEEE 802.11a/b/g/n wireless network device
        rsu(4)        Realtek RTL8188SU/RTL8192SU USB IEEE 802.11b/g/n
                      wireless network device
        rum(4)        Ralink Technology/MediaTek USB IEEE 802.11a/b/g wireless
                      network device
        run(4)        Ralink Technology/MediaTek USB IEEE 802.11a/b/g/n
                      wireless network device
        uath(4)       Atheros USB IEEE 802.11a/b/g wireless network device
        upgt(4)       Conexant/Intersil PrismGT SoftMAC USB IEEE 802.11b/g
                      wireless network device
        ural(4)       Ralink Technology/MediaTek USB IEEE 802.11b/g wireless
                      network device
        urtw(4)       Realtek RTL8187L/RTL8187B USB IEEE 802.11b/g wireless
                      network device
        urtwn(4)      Realtek RTL8188CU/RTL8188EU/RTL8192CU USB IEEE
                      802.11b/g/n wireless network device
        wi(4)         Intersil PRISM 2-3 IEEE 802.11b wireless network device
        zyd(4)        ZyDAS ZD1211/ZD1211B USB IEEE 802.11b/g wireless network

   Serial and parallel interfaces
        moscom(4)     MosChip Semiconductor MCS7703 based USB serial adapter
        uark(4)       Arkmicro Technologies ARK3116 based USB serial adapter
        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)      FTDI USB serial adapter
        uipaq(4)      iPAQ USB units
        ulpt(4)       USB printer support
        umcs(4)       MosChip Semiconductor based USB multiport serial adapter
        umct(4)       MCT USB-RS232 USB serial adapter
        umodem(4)     USB modem support
        umsm(4)       Qualcomm MSM modem device
        uplcom(4)     Prolific PL-2303 USB serial adapter
        uscom(4)      simple USB serial adapters
        uslcom(4)     Silicon Laboratories CP210x based USB serial adapter
        uslhcom(4)    Silicon Laboratories CP2110 based USB serial adapter
        uticom(4)     Texas Instruments TUSB3410 USB serial adapter
        uvisor(4)     USB Handspring Visor
        uvscom(4)     SUNTAC Slipper U VS-10U USB serial adapter

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

   Video devices
        udl(4)        DisplayLink DL-120 / DL-160 USB display devices
        utvfu(4)      USB Fushicai USBTV007 audio/video capture device
        uvideo(4)     USB video devices

   Time receiver devices
        udcf(4)       Gude ADS Expert mouseCLOCK USB timedelta sensor
        umbg(4)       Meinberg Funkuhren USB5131 timedelta sensor

   Radio receiver devices
        udsbr(4)      D-Link DSB-R100 USB radio device

   Human Interface Devices
        ubcmtp(4)     Broadcom trackpad mouse
        uhid(4)       Generic driver for Human Interface Devices
        uhidev(4)     Base driver for all Human Interface Devices
        ukbd(4)       USB keyboards that follow the boot protocol
        ums(4)        USB HID mouse, touchscreen and digitiser devices
        uoaklux(4)    Toradex OAK USB illuminance sensor
        uoakrh(4)     Toradex OAK USB temperature and relative humidity sensor
        uoakv(4)      Toradex OAK USB +/-10V 8channel ADC interface
        upd(4)        USB Power Devices sensor
        uthum(4)      TEMPer HID thermometer and hygrometer
        utpms(4)      Apple touchpad mouse
        utrh(4)       USBRH temperature and humidity sensor
        utwitch(4)    YUREX USB twitch/jiggle of knee sensor
        uwacom(4)     Wacom USB tablets

   WAN network devices
        umb(4)        USB Mobile Broadband Interface Model (MBIM)

   Miscellaneous devices
        uberry(4)     Research In Motion BlackBerry
        ugen(4)       USB generic device support
        ugl(4)        Genesys Logic based host-to-host adapters
        ugold(4)      TEMPer gold HID thermometer and hygrometer
        uonerng(4)    Moonbase Otago OneRNG TRNG
        uow(4)        Maxim/Dallas DS2490 USB 1-Wire adapter
        upl(4)        Prolific based host-to-host adapters
        urng(4)       USB Random Number Generator devices
        usps(4)       USPS composite AC power and temperature sensor
        uts(4)        USB touchscreen support


     There are different versions of the USB which provide different speeds.
     USB 3 can operate up to 5.0Gb/s.  USB 2 operates at 480Mb/s, while USB
     versions 1 and 1.1 operate at 12 Mb/s and 1.5 Mb/s for low speed devices.
     Each USB has a host controller that is the master of the bus; all other
     devices on the bus only speak when spoken to.

     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 is a control endpoint at address 0 and is used to give
     commands to the device 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(8) locators:

     port           Number of the port on closest upstream hub.
     configuration  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      Interface number within a device that an interface driver
                    attaches to.
     vendor         16-bit vendor ID of the device.
     product        16-bit product ID of the device.
     release        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 interfaces 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 device 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 udi_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 reported.

             #define USB_MAX_DEVNAMES 4
             #define USB_MAX_DEVNAMELEN 16
             struct usb_device_info {
                     u_int8_t        udi_bus;
                     u_int8_t        udi_addr;       /* device address */
                     char            udi_product[USB_MAX_STRING_LEN];
                     char            udi_vendor[USB_MAX_STRING_LEN];
                     char            udi_release[8];
                     u_int16_t       udi_productNo;
                     u_int16_t       udi_vendorNo;
                     u_int16_t       udi_releaseNo;
                     u_int8_t        udi_class;
                     u_int8_t        udi_subclass;
                     u_int8_t        udi_protocol;
                     u_int8_t        udi_config;
                     u_int8_t        udi_speed;
             #define USB_SPEED_LOW  1
             #define USB_SPEED_FULL 2
             #define USB_SPEED_HIGH 3
                     int             udi_power;      /* power consumption */
                     int             udi_nports;
                     char            udi_devnames[USB_MAX_DEVNAMES]
                     u_int8_t        udi_ports[16];  /* hub only */
             #define USB_PORT_ENABLED 0xff
             #define USB_PORT_SUSPENDED 0xfe
             #define USB_PORT_POWERED 0xfd
             #define USB_PORT_DISABLED 0xfc
                     char            udi_serial[USB_MAX_STRING_LEN];

             The udi_bus field contains the device unit number of the device.

             The udi_product, udi_vendor, and udi_release fields contain self-
             explanatory descriptions of the device.  The udi_productNo,
             udi_vendorNo, and udi_releaseNo fields contain numeric
             identifiers for the device.

             The udi_class and udi_subclass fields contain the device class
             and subclass.

             The udi_config field shows the current configuration of the

             The udi_protocol field contains the device protocol as given from
             the device.

             The udi_speed field contains the speed of the device.

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

             The udi_devnames field contains the names and instance numbers of
             the device drivers for the devices attached to this device.

             If the device is a hub, the udi_nports field is non-zero and the
             udi_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 uds_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_DEVICE_GET_DDESC struct usb_device_ddesc
             This command can be used to retrieve the device descriptor of a
             device on the bus.  The udd_addr field needs to be filled with
             the bus device address:

             struct usb_device_ddesc {
                     u_int8_t        udd_bus;
                     u_int8_t        udd_addr;       /* device address */
                     usb_device_descriptor_t udd_desc;

             The udd_bus field contains the device unit number.

             The udd_desc field contains the device descriptor structure.

     USB_DEVICE_GET_CDESC struct usb_device_cdesc
             This command can be used to retrieve the configuration descriptor
             for the given configuration of a device on the bus.  The udc_addr
             field needs to be filled with the bus device address.  The
             udc_config_index field needs to be filled with the configuration
             index for the relevant configuration descriptor.  For convenience
             the current configuration can be specified by

             struct usb_device_cdesc {
                     u_int8_t        udc_bus;
                     u_int8_t        udc_addr;       /* device address */
                     int             udc_config_index;
                     usb_config_descriptor_t udc_desc;

             The udc_bus field contains the device unit number.

             The udc_desc field contains the configuration descriptor

     USB_DEVICE_GET_FDESC struct usb_device_fdesc
             This command can be used to retrieve all descriptors for the
             given configuration of a device on the bus.  The udf_addr field
             needs to be filled with the bus device address.  The
             udf_config_index field needs to be filled with the configuration
             index for the relevant configuration descriptor.  For convenience
             the current configuration can be specified by
             USB_CURRENT_CONFIG_INDEX.  The udf_data field needs to point to a
             memory area of the size given in the udf_size field.  The proper
             size can be determined by first issuing a USB_DEVICE_GET_CDESC
             command and inspecting the wTotalLength field:

             struct usb_device_fdesc {
                     u_int8_t         udf_bus;
                     u_int8_t         udf_addr;      /* device address */
                     int              udf_config_index;
                     u_int            udf_size;
                     u_char          *udf_data;

             The udf_bus field contains the device unit number.

             The udf_data field contains all descriptors.

     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 usb_ctl_request structure has the following definition:

             typedef struct {
                     uByte           bmRequestType;
                     uByte           bRequest;
                     uWord           wValue;
                     uWord           wIndex;
                     uWord           wLength;
             } __packed usb_device_request_t;

             struct usb_ctl_request {
                     int     ucr_addr;
                     usb_device_request_t ucr_request;
                     void    *ucr_data;
                     int     ucr_flags;
             #define USBD_SHORT_XFER_OK 0x04 /* allow short reads */
                     int     ucr_actlen;     /* actual length transferred */

             The ucr_addr field identifies the device on which to perform the
             request.  The ucr_request field identifies parameters of the
             request, such as length and type.  The ucr_data field contains
             the location where data will be read from or written to.  The
             ucr_flags field specifies options for the request, and the
             ucr_actlen field contains the actual length transferred as the
             result of the request.

     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 accessed by the UGETW(field) and
     USETW(field, value) macros and double word (32-bit) sized fields must be
     accessed by the UGETDW(field) and USETDW(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).


     usbhidaction(1), usbhidctl(1), ioctl(2), dwctwo(4), ehci(4), ohci(4),
     uhci(4), xhci(4), config(8), usbdevs(8)

     The USB specifications can be found at


     The usb driver appeared in OpenBSD 2.6.

OpenBSD 6.2                   September 12, 2017                   OpenBSD 6.2

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