man/man4/usb.4

.\" $NetBSD: usb.4,v 1.96 2012/01/22 14:15:43 wiz Exp $
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.\" by Lennart Augustsson.
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.Dd January 22, 2012
.Dt USB 4
.Os
.Sh NAME
.Nm usb
.Nd Universal Serial Bus driver
.Sh SYNOPSIS
.Cd "ehci*   at cardbus? function ?"
.Cd "ehci*   at pci? dev ? function ?"
.Cd "ohci*   at cardbus? function ?"
.Cd "ohci*   at pci? dev ? function ?"
.Cd "slhci*  at isa? port ? irq ?"
.Cd "slhci*  at pcmcia? function ?"
.Cd "uhci*   at cardbus? function ?"
.Cd "uhci*   at pci? dev ? function ?"
.Cd "usb*    at ehci? flags X"
.Cd "usb*    at ohci? flags X"
.Cd "usb*    at uhci? flags X"
.Cd "usb*    at slhci? flags X"
.Cd "uhub*   at usb?"
.Cd "uhub*   at uhub? port ? configuration ? interface ? vendor ? product ? release ?"
.Cd "XX*     at uhub? port ? configuration ? interface ? vendor ? product ? release ?"
.Pp
.Cd options USBVERBOSE
.Pp
.In dev/usb/usb.h
.In dev/usb/usbhid.h
.Sh DESCRIPTION
.Nx
provides machine-independent bus support and drivers for
.Tn USB
devices.
.Pp
The
.Nx
.Nm
driver has three layers (like
.Xr scsi 4
and
.Xr pcmcia 4 ) :
the controller, the bus, and the device layer.
The controller attaches to a physical bus (like
.Xr pci 4 ) .
The
.Tn 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
.Tn USB
device tree.
For each
.Tn USB
device there may be additional drivers attached to it.
.Pp
The
.Cm uhub
device controls
.Tn USB
hubs and must always be present since there is at least a root hub in any
.Tn USB
system.
.Pp
The
.Va flags
argument to the
.Va usb
device affects the order in which the device detection happens
during cold boot.
Normally, only the USB host controller and the
.Va usb
device are detected during the autoconfiguration when the
machine is booted.
The rest of the devices are detected once
the system becomes functional and the kernel thread for the
.Va usb
device is started.
Sometimes it is desirable to have a device detected early in the
boot process, e.g., the console keyboard.
To achieve this use a
.Va flags
value of 1.
.Pp
.Nx
supports the following machine-independent
.Tn USB
drivers:
.Ss Storage devices
.Bl -tag -width 12n -offset ind -compact
.It Xr umass 4
.Tn USB
Mass Storage Devices, e.g., external disk drives
.El
.Ss Wired network interfaces
.Bl -tag -width 12n -offset ind -compact
.It Xr aue 4
ADMtek AN986/ADM8511 Pegasus family 10/100 USB Ethernet device
.It Xr axe 4
ASIX Electronics AX88172/AX88178/AX88772 10/100/Gigabit USB Ethernet device
.It Xr cdce 4
USB Communication Device Class Ethernet device
.It Xr cue 4
CATC USB-EL1201A USB Ethernet device
.It Xr kue 4
Kawasaki LSI KL5KUSB101B USB Ethernet device
.It Xr udav 4
Davicom DM9601 10/100 USB Ethernet device
.It Xr url 4
Realtek RTL8150L 10/100 USB Ethernet device
.El
.Ss Wireless network interfaces
.Bl -tag -width 12n -offset ind -compact
.It Xr atu 4
Atmel AT76C50x IEEE 802.11b wireless network device
.It Xr ral 4
Ralink Technology USB IEEE 802.11b/g wireless network device
.It Xr rum 4
Ralink Technology USB IEEE 802.11a/b/g wireless network device
.It Xr ubt 4
USB Bluetooth dongles
.It Xr upgt 4
Conexant/Intersil PrismGT SoftMAC USB 802.11b/g wireless network device
.It Xr zyd 4
ZyDAS ZD1211/ZD1211B USB IEEE 802.11b/g wireless network device
.El
.Ss Serial and parallel interfaces
.Bl -tag -width 12n -offset ind -compact
.It Xr ubsa 4
Belkin USB serial adapter
.It Xr uchcom 4
WinChipHead CH341/340 based USB serial adapter
.It Xr ucom 4
USB tty support
.It Xr ucycom 4
Cypress microcontroller based USB serial adapter
.It Xr uftdi 4
FT8U100AX USB serial adapter
.It Xr ugensa 4
USB generic serial adapter
.It Xr uhmodem 4
USB Huawei 3G wireless modem device
.It Xr uipaq 4
iPAQ USB units
.It Xr ukyopon 4
USB Kyocera AIR-EDGE PHONE device
.It Xr ulpt 4
USB printer support
.It Xr umct 4
MCT USB-RS232 USB serial adapter
.It Xr umodem 4
USB modem support
.It Xr uplcom 4
Prolific PL-2303 USB serial adapter
.It Xr uslsa 4
Silicon Laboratories CP2101/CP2102 based USB serial adapter
.It Xr uvisor 4
USB Handspring Visor
.It Xr uvscom 4
SUNTAC Slipper U VS-10U USB serial adapter
.El
.Ss Audio devices
.Bl -tag -width 12n -offset ind -compact
.It Xr uaudio 4
USB audio devices
.It Xr umidi 4
USB MIDI devices
.It Xr urio 4
Diamond Multimedia Rio MP3 players
.El
.Ss Radio receiver devices
.Bl -tag -width 12n -offset ind -compact
.It Xr udsbr 4
D-Link DSB-R100 USB radio device
.El
.Ss Human Interface Devices
.Bl -tag -width 12n -offset ind -compact
.It Xr uhid 4
Generic driver for Human Interface Devices
.It Xr uhidev 4
Base driver for all Human Interface Devices
.It Xr ukbd 4
.Tn USB
keyboards that follow the boot protocol
.It Xr ums 4
.Tn USB
mouse devices
.El
.Ss Miscellaneous devices
.Bl -tag -width 12n -offset ind -compact
.It Xr stuirda 4
Sigmaltel 4116/4220 USB-IrDA bridge
.It Xr uep 4
USB eGalax touch-panel
.It Xr ugen 4
USB generic devices
.It Xr uirda 4
USB IrDA bridges
.It Xr upl 4
Prolific based host-to-host adapters
.It Xr uscanner 4
USB scanner support
.It Xr usscanner 4
SCSI-over-USB scanners
.It Xr ustir 4
SigmaTel STIr4200 USB IrDA bridges
.It Xr utoppy 4
Topfield TF5000PVR range of digital video recorders
.It Xr uyap 4
USB YAP phone firmware loader
.El
.Sh INTRODUCTION TO USB
The
.Tn USB
1.x is a 12 Mb/s serial bus with 1.5 Mb/s for low speed devices.
.Tn USB
2.x handles 480 Mb/s.
Each
.Tn USB
has a host controller that is the master of the bus;
all other devices on the bus only speak when spoken to.
.Pp
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.
.Pp
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 unidirectional.
.Pp
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.
.Pp
A device may operate in different configurations.
Depending on the
configuration the device may present different sets of endpoints
and interfaces.
.Pp
Each device located on a hub has several
.Xr config 1
locators:
.Bl -tag -compact -width xxxxxxxxx
.It Cd port
this is the number of the port on closest upstream hub.
.It Cd configuration
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.
.It Cd interface
this is the interface number within a device that an interface driver
attaches to.
.It Cd vendor
this is the 16 bit vendor id of the device.
.It Cd product
this is the 16 bit product id of the device.
.It Cd release
this is the 16 bit release (revision) number of the device.
.El
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.
.Pp
The bus enumeration of the
.Tn USB
bus proceeds in several steps:
.Bl -enum
.It
Any device specific driver can attach to the device.
.It
If none is found, any device class specific driver can attach.
.It
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.
.It
If still no drivers have been found, the generic
.Tn USB
driver can attach.
.El
.Sh USB CONTROLLER INTERFACE
Use the following to get access to the
.Tn USB
specific structures and defines.
.Bd -literal
#include \*[Lt]dev/usb/usb.h\*[Gt]
.Ed
.Pp
The
.Pa /dev/usbN
can be opened and a few operations can be performed on it.
The
.Xr poll 2
system call will say that I/O is possible on the controller device when a
.Tn USB
device has been connected or disconnected to the bus.
.Pp
The following
.Xr ioctl 2
commands are supported on the controller device:
.Bl -tag -width xxxxxx
.\" .It Dv USB_DISCOVER
.\" This command will cause a complete bus discovery to be initiated.
.\" If any devices attached or detached from the bus they will be
.\" processed during this command.
.\" This is the only way that new devices are found on the bus.
.It Dv USB_DEVICEINFO Fa "struct usb_device_info"
This command can be used to retrieve some information about a device
on the bus.
The
.Va 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.
.Bd -literal
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
};
.Ed
.Pp
The
.Va product ,
.Va vendor ,
.Va release ,
and
.Va serial
fields contain self-explanatory descriptions of the device.
.Pp
The
.Va class
field contains the device class.
.Pp
The
.Va config
field shows the current configuration of the device.
.Pp
The
.Va lowspeed
field
is set if the device is a
.Tn USB
low speed device.
.Pp
The
.Va power
field shows the power consumption in milli-amps drawn at 5 volts,
or zero if the device is self powered.
.Pp
If the device is a hub the
.Va nports
field is non-zero and the
.Va ports
field contains the addresses of the connected devices.
If no device is connected to a port one of the
.Va USB_PORT_*
values indicates its status.
.It Dv USB_DEVICESTATS Fa "struct usb_device_stats"
This command retrieves statistics about the controller.
.Bd -literal
struct usb_device_stats {
	u_long	uds_requests[4];
};
.Ed
.Pp
The
.Va requests
field is indexed by the transfer kind, i.e.
.Va UE_* ,
and indicates how many transfers of each kind have been completed
by the controller.
.It Dv USB_REQUEST Fa "struct usb_ctl_request"
This command can be used to execute arbitrary requests on the control pipe.
This is
.Em DANGEROUS
and should be used with great care since it
can destroy the bus integrity.
.El
.Pp
The include file
.In dev/usb/usb.h
contains definitions for the types used by the various
.Xr ioctl 2
calls.
The naming convention of the fields for the various
.Tn USB
descriptors exactly follows the naming in the
.Tn USB
specification.
Byte sized fields can be accessed directly, but word (16 bit)
sized fields must be access by the
.Fn UGETW field
and
.Fn USETW field value
macros to handle byte order and alignment properly.
.Pp
The include file
.In dev/usb/usbhid.h
similarly contains the definitions for
Human Interface Devices
.Pq Tn HID .
.Sh USB EVENT INTERFACE
All
.Tn USB
events are reported via the
.Pa /dev/usb
device.
This devices can be opened for reading and each
.Xr read 2
will yield an event record (if something has happened).
The
.Xr poll 2
system call can be used to determine if an event record is available
for reading.
.Pp
The event record has the following definition:
.Bd -literal
struct usb_event {
        int                                 ue_type;
#define USB_EVENT_CTRLR_ATTACH 1
#define USB_EVENT_CTRLR_DETACH 2
#define USB_EVENT_DEVICE_ATTACH 3
#define USB_EVENT_DEVICE_DETACH 4
#define USB_EVENT_DRIVER_ATTACH 5
#define USB_EVENT_DRIVER_DETACH 6
        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;
};
.Ed
.Pp
The
.Va 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.
.Pp
The
.Va ue_bus
contains the number of the
.Tn USB
bus for host controller events.
.Pp
The
.Va ue_device
record contains information about the device in a device event event.
.Pp
The
.Va 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
.Va ue_devname
contains the name of the device (driver) as seen in, e.g.,
kernel messages.
.Pp
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.
.Sh KERNEL THREADS
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
.Va usbN
where
.Va N
is the bus number.
.Pp
In addition there is a kernel thread,
.Va usbtask ,
which handles various minor tasks that are initiated from
an interrupt context, but need to sleep, e.g., time-out
abort of transfers.
.Sh SEE ALSO
.Xr usbhidaction 1 ,
.Xr usbhidctl 1 ,
.Xr cardbus 4 ,
.Xr ehci 4 ,
.Xr isa 4 ,
.Xr ohci 4 ,
.Xr pci 4 ,
.Xr pcmcia 4 ,
.Xr slhci 4 ,
.Xr uhci 4 ,
.Xr usbdevs 8
.Rs
.%T Universal Serial Bus Specifications Documents
.%U http://www.usb.org/developers/docs/
.Re
.Sh HISTORY
The
.Nm
driver
appeared in
.Nx 1.4 .
.Sh BUGS
There should be a serial number locator, but
.Nx
does not have string valued locators.