ugen(4)
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UGEN(4) NetBSD Programmer's Manual UGEN(4)
NAME
ugen - USB generic device support
SYNOPSIS
ugen* at uhub?
DESCRIPTION
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, but an open(2) cannot specify O_RDWR
mode; the endpoint must be opened once for each direction.
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 IO on a bulk endpoint read(2) and write(2) should be used. All
IO 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.
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
field.
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
USB_CURRENT_CONFIG_INDEX.
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
USB_CURRENT_ALT_INDEX.
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 of the size given
in the size field. The proper size can be determined by first
issuing 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-
dex.
struct usb_string_desc {
int string_index;
int language_id;
usb_string_descriptor_t desc;
};
USB_DO_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.
struct usb_ctl_request {
int addr;
usb_device_request_t request;
void *data;
};
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
USB_CURRENT_ALT_INDEX.
SEE ALSO
usb(4)
HISTORY
The ugen driver appeared in NetBSD 1.4.
BUGS
The driver is not yet finished; there is no access to isochronous end-
points.
NetBSD 1.4 July 12, 1998 3
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