.\"	$OpenBSD: ugen.4,v 1.6 2001/10/05 14:45:53 mpech Exp $
.\"	$NetBSD: ugen.4,v 1.7 1999/07/30 01:32:05 augustss Exp $
.\"
.\" Copyright (c) 1999 The NetBSD Foundation, Inc.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Lennart Augustsson.
.\"
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.Dd July 12, 1998
.Dt UGEN 4
.Os
.Sh NAME
.Nm ugen
.Nd USB generic device support
.Sh SYNOPSIS
.Cd "ugen* at uhub?"
.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, but an
.Xr open 2
cannot specify
.Dv O_RDWR
mode; the endpoint must be opened once for each direction.
.Pp
To find out what endpoints exist there are a series of
.Xr ioctl 2
operations available for 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.
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 only be in.
To perform input from an interrupt endpoint
.Xr read 2
should be used.
A moderate amount of buffering is done by the driver.
.Pp
The control endpoint (endpoint 0) handles the following
.Xr ioctl 2
calls:
.Pp
.Bl -tag -width indent -compact
.It Dv USB_SET_SHORT_XFER (int)
Allow short read transfer.
Normally a transfer from the device which is shorter than the request
specified is reported as an error.
.Pp
.It Dv USB_GET_CONFIG (int)
Get the device configuration number.
.Pp
.It Dv USB_SET_CONFIG (int)
Set the device into the given configuration number.
This operation can only be performed when the control endpoint
is the sole open endpoint.
.Pp
.It Dv USB_GET_ALTINTERFACE (struct usb_alt_interface)
Get the alternative setting number for the interface with the given
index.
The
.Fa config_index
is ignored in this call.
.Bd -literal
struct usb_alt_interface {
	int	config_index;
	int	interface_index;
	int	alt_no;
};
.Ed
.It Dv USB_SET_ALTINTERFACE (struct usb_alt_interface)
Set the alternative setting to the given number in the interface with the
given index.
The
.Fa config_index
is ignored in this call.
.Pp
This operation can only be performed when no endpoints for the interface
are open.
.Pp
.It Dv USB_GET_NO_ALT (struct usb_alt_interface)
Return the number of different alternate settings in the
.Fa alt_no
field.
.Pp
.It Dv USB_GET_DEVICE_DESC (usb_device_descriptor_t)
Return the device descriptor.
.Pp
.It Dv USB_GET_CONFIG_DESC (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	config_index;
	usb_config_descriptor_t desc;
};
.Ed
.Pp
.It Dv USB_GET_INTERFACE_DESC (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	config_index;
	int	interface_index;
	int	alt_index;
	usb_interface_descriptor_t desc;
};
.Ed
.Pp
.It Dv USB_GET_ENDPOINT_DESC (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	config_index;
	int	interface_index;
	int	alt_index;
	int	endpoint_index;
	usb_endpoint_descriptor_t desc;
};
.Ed
.Pp
.It Dv USB_GET_FULL_DESC (struct usb_full_desc)
Return all the descriptors for the given configuration.
.Bd -literal
struct usb_full_desc {
	int	config_index;
	u_int	size;
	u_char	*data;
};
.Ed
.Pp
The
.Fa data
field should point to a memory area of the size given in the
.Fa size
field.
The proper size can be determined by first issuing a
.Dv USB_GET_CONFIG_DESC
and inspecting the
.Fa wTotalLength
field.
.Pp
.It Dv USB_GET_STRING_DESC (struct usb_string_desc)
Get a string descriptor for the given language id and
string index.
.Bd -literal
struct usb_string_desc {
	int	string_index;
	int	language_id;
	usb_string_descriptor_t desc;
};
.Ed
.Pp
.It Dv USB_DO_REQUEST
Send a USB request to the device on the control endpoint.
Any data sent to/from the device is located at
.Fa data .
The size of the transferred data is determined from the
.Fa request .
The
.Fa addr
field is ignored in this call.
.Bd -literal
struct usb_ctl_request {
	int	addr;
	usb_device_request_t request;
	void	*data;
};
.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.
.Pp
.It Dv USB_GET_DEVICEINFO (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 use 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
.Fa interface_index
from 0 to
.Fa config_desc->bNumInterface-1
and for each of these iterating the
.Fa endpoint_index
from 0 to
.Fa interface_desc->bNumEndpoints .
The
.Fa config_index
should set to
.Dv USB_CURRENT_CONFIG_INDEX
and
.Fa alt_index
should be set to
.Dv USB_CURRENT_ALT_INDEX .
.Sh SEE ALSO
.Xr usb 4
.Sh HISTORY
The
.Nm
driver
appeared in
.Ox 2.6 .
.Sh BUGS
The driver is not yet finished; there is no access to isochronous endpoints.