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UGEN(4)			 BSD Kernel Interfaces Manual		       UGEN(4)

     ugen -- USB generic device	support

     device ugen

     The ugen 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.

     There can be up to	127 USB	devices	connected to a USB bus.	 Each USB de-
     vice can have up to 16 endpoints.	Each of	these endpoints	will communi-
     cate in one of four different modes: control, isochronous,	bulk, or in-
     terrupt.  Each of the endpoints will have a different device node.	 The
     four least	significant bits in the	minor device number determines which
     endpoint the device accesses and the rest of the bits determines which
     USB device.

     If	an endpoint address is used both for input and output the device can
     be	opened for both	read or	write.

     To	find out what endpoints	that exist there are a series of ioctl(2) op-
     eration on	the control endpoint that returns the USB descriptors of the
     device, configurations, interfaces, and endpoints.

     The control transfer mode can only	happen on the control endpoint which
     is	always endpoint	0.  The	control	endpoint accepts request and may re-
     spond with	an answer to such request.  Control request are	issued by
     ioctl(2) calls.

     The bulk transfer mode can	be in or out depending on the endpoint.	 To
     perform I/O on a bulk endpoint read(2) and	write(2) should	be used.  All
     I/O operations on a bulk endpoint are unbuffered.

     The interrupt transfer mode can only be in.  To perform input from	an in-
     terrupt endpoint read(2) should be	used.  A moderate amount of buffering
     is	done by	the driver.

     All endpoints handle the following	ioctl(2) calls:

	     Allow short read transfer.	 Normally a transfer from the device
	     which is shorter than the request specified is reported as	an er-

     USB_SET_TIMEOUT (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.

     The control endpoint (endpoint 0) handles the following ioctl(2) calls:

     USB_GET_CONFIG (int)
	     Get the device configuration number.

     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.

     USB_GET_ALTINTERFACE (struct usb_alt_interface)
	     Get the alternative setting number	for the	interface with the
	     given index.  The config_index is ignored in this call.

	     struct usb_alt_interface {
		     int     config_index;
		     int     interface_index;
		     int     alt_no;

     USB_SET_ALTINTERFACE (struct usb_alt_interface)
	     Set the alternative setting to the	given number in	the interface
	     with the given index.  The	config_index is	ignored	in this	call.

	     This operation can	only be	performed when no endpoints for	the
	     interface are open.

     USB_GET_NO_ALT (struct usb_alt_interface)
	     Return the	number of different alternate settings in the alt_no

     USB_GET_DEVICE_DESC (usb_device_descriptor_t)
	     Return the	device descriptor.

     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

	     struct usb_config_desc {
		     int     config_index;
		     usb_config_descriptor_t desc;

     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

	     struct usb_interface_desc {
		     int     config_index;
		     int     interface_index;
		     int     alt_index;
		     usb_interface_descriptor_t	desc;

     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 end-
	     point index.

	     struct usb_endpoint_desc {
		     int     config_index;
		     int     interface_index;
		     int     alt_index;
		     int     endpoint_index;
		     usb_endpoint_descriptor_t desc;

     USB_GET_FULL_DESC (struct usb_full_desc)
	     Return all	the descriptors	for the	given configuration.

	     struct usb_full_desc {
		     int     config_index;
		     u_int   size;
		     u_char  *data;
	     The data field should point to a memory area of the size given in
	     the size field.  The proper size can be determined	by first issu-
	     ing a USB_GET_CONFIG_DESC and inspecting the wTotalLength field.

     USB_GET_STRING_DESC (struct usb_string_desc)
	     Get a string descriptor for the given language ID and string in-

	     struct usb_string_desc {
		     int     string_index;
		     int     language_id;
		     usb_string_descriptor_t desc;

     USB_DO_REQUEST (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	data.  The size	of the
	     transferred data is determined from the request.  The addr	field
	     is	ignored	in this	call.  The flags field can be used to flag
	     that the request is allowed to be shorter than the	requested
	     size, and the actlen will contain the actual size on completion.

	     struct usb_ctl_request {
		     int     addr;
		     usb_device_request_t request;
		     void    *data;
		     int     flags;
	     #define USBD_SHORT_XFER_OK	     0x04    /*	allow short reads */
		     int     actlen;	     /*	actual length transferred */
	     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.

     USB_GET_DEVICEINFO	(struct	usb_device_info)
	     Get an information	summary	for the	device.	 This call will	not
	     issue any USB transactions.

     Note that there are two different ways of addressing configurations, in-
     terfaces, 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.

     Example: all endpoints (except the	control	endpoint) for the current con-
     figuration	can be found by	iterating the interface_index from 0 to
     config_desc-_bNumInterface-1 and for each of these	iterating the
     endpoint_index from 0 to interface_desc-_bNumEndpoints.  The config_index
     should set	to USB_CURRENT_CONFIG_INDEX and	alt_index should be set	to

     /dev/ugenN.EE  Endpoint EE	of device N.


     The ugen driver appeared in NetBSD	1.4.

BSD				 July 12, 1998				   BSD


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