man/man4/usb.4

.\" $NetBSD: usb.4,v 1.51 2002/05/13 05:41:31 ichiro Exp $
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.\" by Lennart Augustsson.
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.Dd July 12, 1998
.Dt USB 4
.Os
.Sh NAME
.Nm usb
.Nd Universal Serial Bus driver
.Sh SYNOPSIS
.Cd "ehci*   at cardbus? dev ? function ?"
.Cd "ehci*   at pci? dev ? function ?"
.Cd "ohci*   at cardbus? dev ? function ?"
.Cd "ohci*   at pci? dev ? 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 "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 "#include \*[Lt]dev/usb/usb.h\*[Gt]"
.Cd "#include \*[Lt]dev/usb/usbhid.h\*[Gt]"
.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 controller.
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.
.Sh SUPPORTED DEVICES
.Nx
includes machine-independent
.Tn USB
drivers, sorted by driver name:
.Bl -tag -width usscanner -offset indent
.It aue
driver for ADMtek AN986 Pegasus USB Ethernet.
.It cue
driver for CATC USB-EL1201A USB Ethernet.
.It kue
driver for Kawasaki LSI KL5KUSB101B USB Ethernet.
.It url
driver for Realtek RTL8150L USB Ethernet.
.It uaudio
driver for audio devices.
.It udsbr
driver for D-Link DSB-R100 USB radio.
.It uftdi
driver for FTDI based serial adapters.
.It ugen
generic driver for
.Tn USB
devices.
.It uhidev
top level HID driver.
.It uhid
generic driver for Human Interface Devices.
.It uirda
driver for USB-IrDA bridges.
.It ukbd
keyboard driver.
.It ulpt
printer driver.
.It umass
driver for mass storage devices, such as disks.
.It umidi
driver for MIDI devices.
.It umodem
driver for communication devices that use the Abstract Control Model.
.It ums
mouse driver.
.It upl
driver for
.Tn Prolific
host-to-host adapter.
.It uplcom
driver for Prolific 2303 serial adapter.
.It umct
driver for MCT USB-RS232 serial adapter.
.It urio
driver for the
.Tn Diamond
Rio 500 MP3 player.
.It uscanner
driver for some USB scanners.
.It usscanner
driver for some SCSI-over-USB scanners.
.It ustir
driver for SigmaTel STIr4200 USB-IrDA bridges.
.It uvisor
Handspring Visor driver.
.It uvscom
driver for SUNTAC Slipper U VS-10U serial adapter.
.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 8
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 to 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]sys/dev/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 {
	u_int8_t	bus;
	u_int8_t	addr;
	usb_event_cookie_t cookie;
	char		product[USB_MAX_STRING_LEN];
	char		vendor[USB_MAX_STRING_LEN];
	char		release[8];
	u_int16_t	productNo;
	u_int16_t	vendorNo;
	u_int16_t	releaseNo;
	u_int8_t	class;
	u_int8_t	subclass;
	u_int8_t	protocol;
	u_int8_t	config;
	u_int8_t	lowspeed;
	int		power;
	int		nports;
	char		devnames[USB_MAX_DEVNAMES][USB_MAX_DEVNAMELEN];
	u_int8_t	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 ,
and
.Va release
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	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 that has 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
.Aq Pa 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
.Aq Pa 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
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.
.br
The
.Va ue_bus
contains the number of the
.Tn USB
bus for host controller events.
.br
The
.Va ue_device
record contains information about the device in a device event event.
.br
The
.Va ue_cookie
is an opaque value that uniquely determines which 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 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 SEE ALSO
The
.Tn USB
specifications can be found at:
.D1 http://www.usb.org/developers/docs.html
.Pp
.Xr usb 3 ,
.Xr aue 4 ,
.Xr cardbus 4 ,
.Xr cue 4 ,
.Xr ehci 4 ,
.Xr kue 4 ,
.Xr ohci 4 ,
.Xr pci 4 ,
.Xr uaudio 4 ,
.Xr ucom 4 ,
.Xr udsbr 4 ,
.Xr ugen 4 ,
.Xr uhci 4 ,
.Xr uhid 4 ,
.Xr uhidev 4 ,
.Xr uirda 4 ,
.Xr ukbd 4 ,
.Xr ulpt 4 ,
.Xr umass 4 ,
.Xr umidi 4 ,
.Xr ums 4 ,
.Xr upl 4 ,
.Xr url 4 ,
.Xr urio 4 ,
.Xr uscanner 4 ,
.Xr usscanner 4 ,
.Xr ustir 4 ,
.Xr uvisor 4 ,
.Xr usbdevs 8
.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.