NAME
usb
—
introduction to Universal Serial Bus
support
SYNOPSIS
# zaurus specific
ohci0 at pxaip?
# all architectures
ehci* at cardbus?
uhci* at cardbus?
ohci* at cardbus?
ehci* at pci?
uhci* at pci?
ohci* at pci?
usb* at ehci? flags 0x00
usb* at uhci? flags 0x00
usb* at ohci? 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/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 10/100 USB 2.0 Ethernet device
- udav(4)
- Davicom DM9601 10/100 USB Ethernet device
- ueagle(4)
- Analog Devices Eagle ADSL modems
- 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/g/n wireless network device
- atu(4)
- Atmel AT76C50x IEEE 802.11b wireless network device
- otus(4)
- Atheros USB IEEE 802.11a/g/n wireless network device
- rsu(4)
- Realtek RTL8188SU/RTL8192SU USB IEEE 802.11b/g/n wireless network device
- rum(4)
- Ralink Technology USB IEEE 802.11a/b/g wireless network device
- run(4)
- Ralink Technology USB IEEE 802.11a/g/n wireless network device
- uath(4)
- Atheros USB IEEE 802.11a/b/g wireless network device
- ubt(4)
- Bluetooth adapters
- upgt(4)
- Conexant/Intersil PrismGT SoftMAC USB IEEE 802.11b/g wireless network device
- ural(4)
- Ralink Technology 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/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 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
- uftdi(4)
- FTDI USB serial adapter
- uipaq(4)
- iPAQ USB units
- ulpt(4)
- USB printer support
- 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
- uslcom(4)
- Silicon Laboratories CP2101/CP2102 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
Video devices
Time receiver devices
Radio receiver devices
- udsbr(4)
- D-Link DSB-R100 USB radio device
Human Interface Devices
- tpms(4)
- Apple touchpad mouse
- ucycom(4)
- Cypress microcontroller based USB serial adapter
- uhid(4)
- Generic driver for Human Interface Devices
- uhidev(4)
- Base driver for all Human Interface Devices
- uhts(4)
- USB HID touchscreen support
- ukbd(4)
- USB keyboards that follow the boot protocol
- ums(4)
- USB mouse devices
- uthum(4)
- TEMPer USB temperature and humidity sensor
- utrh(4)
- USBRH temperature and humidity sensor
Miscellaneous devices
- uberry(4)
- Research In Motion Blackberry
- ugen(4)
- USB generic device support
- uow(4)
- Maxim/Dallas DS2490 USB 1-Wire adapter
- upl(4)
- Prolific based host-to-host adapters
- uscanner(4)
- USB scanner support
- usps(4)
- USPS composite AC power and temperature sensor
- uts(4)
- USB touchscreen support
- uyap(4)
- USB YAP phone firmware loader
INTRODUCTION TO USB
There are different versions of the USB which provide different speeds. 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 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 */ usb_event_cookie_t udi_cookie; 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] [USB_MAX_DEVNAMELEN]; 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 };
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_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).
SEE ALSO
usbhidaction(1), usbhidctl(1), ioctl(2), ehci(4), ohci(4), uhci(4), config(8), usbdevs(8)
The USB specifications can be found at:
http://www.usb.org/developers/docs/
HISTORY
The usb
driver appeared in
OpenBSD 2.6.