USB(4) - Device Drivers Manual #

USB(4) - Device Drivers Manual

NAME #

usb, uhub - introduction to Universal Serial Bus support

SYNOPSIS #

# 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>

DESCRIPTION #

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 device

axe(4)

ASIX Electronics AX88172/AX88178/AX88772 10/100/1Gb USB Ethernet device

axen(4)

ASIX Electronics AX88179/AX88179A 10/100/1Gb 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 10/100/1Gb USB Ethernet device

smsc(4)

SMSC LAN95xx 10/100 USB Ethernet device

uaq(4)

Aquantia AQC111U/AQC112U 100/1Gb/2.5Gb/5Gb USB Ethernet device

udav(4)

Davicom DM9601 10/100 USB Ethernet device

ure(4)

Realtek RTL8152/RTL8153/RTL8153B/RTL8153D/RTL8156 10/100/1Gb/2.5Gb USB Ethernet device

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

bwfm(4)

Broadcom and Cypress IEEE 802.11a/ac/ax/b/g/n wireless network device

mtw(4)

MediaTek USB IEEE 802.11b/g/n 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/RTL8188FTV/RTL8192CU/RTL8192EU 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 device

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

ucrcom(4)

Chromebook USB serial console

ucycom(4)

Cypress microcontroller based USB serial adapter

uftdi(4)

FTDI USB serial adapter

uipaq(4)

iPAQ USB units

ukspan(4)

Keyspan USB serial adapter

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

uxrcom(4)

Exar XR21V1410 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 #

fido(4)

FIDO/U2F security keys

ubcmtp(4)

Broadcom trackpad mouse

ucc(4)

Consumer Control keyboards

ugold(4)

TEMPer gold HID thermometer and hygrometer

uhid(4)

Generic driver for Human Interface Devices

uhidev(4)

Base driver for all Human Interface Devices

uhidpp(4)

Logitech HID++ devices

ujoy(4)

USB joysticks/gamecontrollers

ukbd(4)

USB keyboards that follow the boot protocol

ums(4)

USB HID mouse, touchscreen and digitiser devices

umstc(4)

Microsoft Surface Type Cover keyboard

umt(4)

USB HID multitouch touchpad 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

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

INTRODUCTION TO USB #

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 unidirectional.

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 interfaces.

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:

Any device-specific driver can attach to the device.
If none is found, any device class specific driver can attach.
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.
If still no drivers have been found, the generic USB driver can attach.

USB CONTROLLER INTERFACE #

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

#include <dev/usb/usb.h>

The /dev/usbN device can be opened and a few operations can be performed on it. 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 #define USB_SPEED_SUPER 4 u_int8_t udi_port; int udi_power; /* power consumption */ int udi_nports; char udi_devnames[USB_MAX_DEVNAMES] [USB_MAX_DEVNAMELEN]; u_int32_t udi_ports[16]; /* hub only */ 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 device.

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 USB_CURRENT_CONFIG_INDEX:

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 structure.

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).

HISTORY #

The usb driver appeared in OpenBSD 2.6.

OpenBSD 7.5 - January 4, 2024