freebsd-skq/share/man/man4/ugen.4

.\" $NetBSD: ugen.4,v 1.13 2001/09/11 22:52:54 wiz Exp $
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.\" by Lennart Augustsson.
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.Dd April 24, 2018
.Dt UGEN 4
.Os
.Sh NAME
.Nm ugen
.Nd USB generic device support
.Sh SYNOPSIS
.Nm
is integrated into the
.Xr usb 4
kernel module.
.Sh DESCRIPTION
The
.Nm
driver provides support for all USB devices that do not have
a special driver.
It supports access to all parts of the device,
but not in a way that is as convenient as a special purpose driver.
.Pp
There can be up to 127 USB devices connected to a USB bus.
Each USB device can have up to 16 endpoints.
Each of these endpoints
will communicate in one of four different modes: control, isochronous,
bulk, or interrupt.
Each of the endpoints will have a different
device node.
The four least significant bits in the minor device
number determine which endpoint the device accesses, and the rest
of the bits determine which USB device.
.Pp
If an endpoint address is used both for input and output, the device
can be opened for both read or write.
.Pp
To find out which endpoints exist, there are a series of
.Xr ioctl 2
operations on the control endpoint that return the USB descriptors
of the device, configurations, interfaces, and endpoints.
.Pp
The control transfer mode can only happen on the control endpoint
which is always endpoint 0.
The control endpoint accepts a request
and may respond with an answer to such a request.
Control requests
are issued by
.Xr ioctl 2
calls.
.\" .Pp
.\" The isochronous transfer mode can be in or out depending on the
.\" endpoint.
.\" To perform I/O on an isochronous endpoint
.\" .Xr read 2
.\" and
.\" .Xr write 2
.\" should be used.
.\" Before any I/O operations can take place the transfer rate in
.\" bytes/second has to be set.
.\" This is done with
.\" .Xr ioctl 2
.\" .Dv USB_SET_ISO_RATE .
.\" Performing this call sets up a buffer corresponding to
.\" about 1 second of data.
.Pp
The bulk transfer mode can be in or out depending on the
endpoint.
To perform I/O on a bulk endpoint
.Xr read 2
and
.Xr write 2
should be used.
All I/O operations on a bulk endpoint are unbuffered.
.Pp
The interrupt transfer mode can be in or out depending on the
endpoint.
To perform I/O on an interrupt endpoint
.Xr read 2
and
.Xr write 2
should be used.
A moderate amount of buffering is done
by the driver.
.Pp
All endpoints handle the following
.Xr ioctl 2
calls:
.Bl -tag -width indent
.It Dv USB_SET_SHORT_XFER Pq Vt int
Allow short read transfer.
Normally a transfer from the device
which is shorter than the request specified is reported as an
error.
.It Dv USB_SET_TIMEOUT Pq Vt int
Set the timeout on the device operations
The time is specified in milliseconds.
The value 0 is used to indicate that there is
no timeout.
.El
.Pp
The control endpoint (endpoint 0) handles the following
.Xr ioctl 2
calls:
.Bl -tag -width indent
.It Dv USB_GET_CONFIG Pq Vt int
Get the device configuration number.
.It Dv USB_SET_CONFIG Pq Vt int
Set the device into the given configuration number.
.Pp
This operation can only be performed when the control endpoint
is the sole open endpoint.
.It Dv USB_GET_ALTINTERFACE Pq Vt "struct usb_alt_interface"
Get the alternative setting number for the interface with the given
index.
The
.Va uai_config_index
is ignored in this call.
.Bd -literal
struct usb_alt_interface {
	int	uai_config_index;
	int	uai_interface_index;
	int	uai_alt_no;
};
.Ed
.It Dv USB_SET_ALTINTERFACE Pq Vt "struct usb_alt_interface"
Set the alternative setting to the given number in the interface with the
given index.
The
.Va uai_config_index
is ignored in this call.
.Pp
This operation can only be performed when no endpoints for the interface
are open.
.It Dv USB_GET_NO_ALT Pq Vt "struct usb_alt_interface"
Return the number of different alternate settings in the
.Va uai_alt_no
field.
.It Dv USB_GET_DEVICE_DESC Pq Vt usb_device_descriptor_t
Return the device descriptor.
.It Dv USB_GET_CONFIG_DESC Pq Vt "struct usb_config_desc"
Return the descriptor for the configuration with the given index.
For convenience, the current configuration can be specified by
.Dv USB_CURRENT_CONFIG_INDEX .
.Bd -literal
struct usb_config_desc {
	int	ucd_config_index;
	usb_config_descriptor_t ucd_desc;
};
.Ed
.It Dv USB_GET_INTERFACE_DESC Pq Vt "struct usb_interface_desc"
Return the interface descriptor for an interface specified by its
configuration index, interface index, and alternative index.
For convenience, the current alternative can be specified by
.Dv USB_CURRENT_ALT_INDEX .
.Bd -literal
struct usb_interface_desc {
	int	uid_config_index;
	int	uid_interface_index;
	int	uid_alt_index;
	usb_interface_descriptor_t uid_desc;
};
.Ed
.It Dv USB_GET_ENDPOINT_DESC Pq Vt "struct usb_endpoint_desc"
Return the endpoint descriptor for the endpoint specified by its
configuration index, interface index, alternative index, and
endpoint index.
.Bd -literal
struct usb_endpoint_desc {
	int	ued_config_index;
	int	ued_interface_index;
	int	ued_alt_index;
	int	ued_endpoint_index;
	usb_endpoint_descriptor_t ued_desc;
};
.Ed
.It Dv USB_GET_FULL_DESC Pq Vt "struct usb_full_desc"
Return all the descriptors for the given configuration.
.Bd -literal
struct usb_full_desc {
	int	ufd_config_index;
	u_int	ufd_size;
	u_char	*ufd_data;
};
.Ed
The
.Va ufd_data
field should point to a memory area of the size given in the
.Va ufd_size
field.
The proper size can be determined by first issuing a
.Dv USB_GET_CONFIG_DESC
and inspecting the
.Va wTotalLength
field.
.It Dv USB_GET_STRING_DESC Pq Vt "struct usb_string_desc"
Get a string descriptor for the given language ID and
string index.
.Bd -literal
struct usb_string_desc {
	int	usd_string_index;
	int	usd_language_id;
	usb_string_descriptor_t usd_desc;
};
.Ed
.It Dv USB_DO_REQUEST Pq Vt "struct usb_ctl_request"
Send a USB request to the device on the control endpoint.
Any data sent to/from the device is located at
.Va ucr_data .
The size of the transferred data is determined from the
.Va ucr_request .
The
.Va ucr_addr
field is ignored in this call.
The
.Va ucr_flags
field can be used to flag that the request is allowed to
be shorter than the requested size, and
.Va ucr_actlen
will contain the actual size on completion.
.Bd -literal
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 */
};
.Ed
This is a dangerous operation in that it can perform arbitrary operations
on the device.
Some of the most dangerous (e.g., changing the device
address) are not allowed.
.It Dv USB_GET_DEVICEINFO Pq Vt "struct usb_device_info"
Get an information summary for the device.
This call will not issue any USB transactions.
.El
.Pp
Note that there are two different ways of addressing configurations,
interfaces, alternatives, and endpoints: by index or by number.
The index is the ordinal number (starting from 0) of the descriptor
as presented by the device.
The number is the respective number of
the entity as found in its descriptor.
Enumeration of descriptors
uses the index, getting and setting typically uses numbers.
.Pp
Example:
all endpoints (except the control endpoint) for the current configuration
can be found by iterating the
.Va interface_index
from 0 to
.Va config_desc->bNumInterface Ns \-1
and for each of these, iterating the
.Va endpoint_index
from 0 to
.Va interface_desc->bNumEndpoints .
The
.Va config_index
should be set to
.Dv USB_CURRENT_CONFIG_INDEX
and
.Va alt_index
should be set to
.Dv USB_CURRENT_ALT_INDEX .
.Sh SYSCTL VARIABLES
The following variables are available as both
.Xr sysctl 8
variables and
.Xr loader 8
tunables:
.Bl -tag -width indent
.It Va hw.usb.ugen.debug
Debug output level, where 0 is debugging disabled and larger values increase
debug message verbosity.
Default is 0.
.El
.Sh FILES
.Bl -tag -width ".Pa /dev/ugen Ns Ar N Ns Pa \&. Ns Ar E" -compact
.It Pa /dev/ugen Ns Ar N Ns Pa \&. Ns Ar E
Endpoint
.Ar E
of device
.Ar N .
.El
.Sh SEE ALSO
.Xr usb 4
.Sh HISTORY
The
.Nm
driver
appeared in
.Nx 1.4 .
.\" .Sh BUGS
.\" The driver is not yet finished; there is no access to isochronous endpoints.