ugen - USB generic device support
ugen* at uhub? port ? configuration ?
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 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.
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 exist there are a series of
ioctl(2) operations
available for the control endpoint that return 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. Control requests 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 interrupt
endpoint read(2) should be used. A moderate amount
of buffering
is done by the driver.
All endpoints handle the following ioctl(2) calls:
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.
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 uai_config_index is ignored in
this call.
struct usb_alt_interface {
int uai_config_index;
int uai_interface_index;
int uai_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 uai_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
uai_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 ucd_config_index;
usb_config_descriptor_t ucd_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 uid_config_index;
int uid_interface_index;
int uid_alt_index;
usb_interface_descriptor_t uid_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 endpoint
index.
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;
};
USB_GET_FULL_DESC (struct usb_full_desc)
Return all the descriptors for the given configuration.
struct usb_full_desc {
int ufd_config_index;
u_int ufd_size;
u_char *ufd_data;
};
The ufd_data field should point to a memory area of
the size given
in the ufd_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 index.
struct usb_string_desc {
int usd_string_index;
int usd_language_id;
usb_string_descriptor_t usd_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 ucr_data.
The size of
the transferred data is determined from the
ucr_request. The
ucr_addr field is ignored in this call.
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 */
};
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, 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.
Example: All endpoints (except the control endpoint) for the
current configuration
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-*(GtbNumEndpoints.
The
config_index should set to USB_CURRENT_CONFIG_INDEX and
alt_index should
be set to USB_CURRENT_ALT_INDEX.
/dev/ugenN.EE Endpoint EE of device N.
intro(4), uhub(4), usb(4)
The ugen driver appeared in OpenBSD 2.6.
The driver is not yet finished; there is no access to
isochronous endpoints.
OpenBSD 3.6 December 15, 2003
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