.\" $NetBSD: uhid.4,v 1.22 2012/05/14 04:55:07 wiz Exp $
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.\" by Lennart Augustsson.
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.Dd May 14, 2012
.Dt UHID 4
.Os
.Sh NAME
.Nm uhid
.Nd USB generic HID support
.Sh SYNOPSIS
.Cd "uhid* at uhidev? reportid ? flags N"
.Sh DESCRIPTION
The
.Nm
driver provides support for all HID (Human Interface Device) interfaces
in USB devices that do not have a special driver.
.Pp
Normally the
.Nm
driver is used when no other HID driver attaches to a device.
If
.Dq flags 1
is specified, the
.Nm
driver will instead attach with a very high priority and always be used.
Together with the
.Cd vendor
and
.Cd product
locators on the
.Xr uhidev 4
driver this can be used to force the
.Nm
driver to be used for a certain device.
.Pp
The device handles the following
.Xr ioctl 2
calls:
.Pp
.Bl -tag -width indent
.It Dv USB_GET_REPORT_ID (int)
Get the report identifier used by this HID report.
.It Dv USB_GET_REPORT_DESC (struct usb_ctl_report_desc)
Get the HID report descriptor.
Using this descriptor the exact layout and meaning of data to/from
the device can be found.
The report descriptor is delivered without any processing.
.Bd -literal
struct usb_ctl_report_desc {
    int     ucrd_size;
    u_char  ucrd_data[1024];	/* filled data size will vary */
};
.Ed
.It Dv USB_SET_IMMED (int)
Sets the device in a mode where each
.Xr read 2
will return the current value of the input report.
Normally a
.Xr read 2
will only return the data that the device reports on its
interrupt pipe.
This call may fail if the device does not support this feature.
.It Dv USB_GET_REPORT (struct usb_ctl_report)
Get a report from the device without waiting for data on
the interrupt pipe.
The
.Dv report
field indicates which report is requested.
It should be
.Dv UHID_INPUT_REPORT ,
.Dv UHID_OUTPUT_REPORT ,
or
.Dv UHID_FEATURE_REPORT .
This call may fail if the device does not support this feature.
.Bd -literal
struct usb_ctl_report {
	int     ucr_report;
	u_char	ucr_data[1024];	/* used data size will vary */
};
.Ed
.It Dv USB_SET_REPORT (struct usb_ctl_report)
Set a report in the device.
The
.Dv report
field indicates which report is to be set.
It should be
.Dv UHID_INPUT_REPORT ,
.Dv UHID_OUTPUT_REPORT ,
or
.Dv UHID_FEATURE_REPORT .
This call may fail if the device does not support this feature.
.It Dv USB_GET_DEVICE_DESC (usb_device_descriptor_t)
Return the device descriptor.
.It Dv USB_GET_DEVICEINFO (struct usb_device_info)
Get an information summary for the device.
This call will not issue any USB transactions.
.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	usd_string_index;
	int	usd_language_id;
	usb_string_descriptor_t usd_desc;
};
.Ed
.El
.Pp
Use
.Xr read 2
to get data from the device.
Data should be read in chunks of the size prescribed by the report
descriptor.
.Pp
Use
.Xr write 2
send data to the device.
Data should be written in chunks of the size prescribed by the
report descriptor.
.Sh FILES
.Bl -tag -width Pa
.It Pa /dev/uhid?
.El
.Sh SEE ALSO
.Xr usbhidaction 1 ,
.Xr usbhidctl 1 ,
.Xr uhidev 4 ,
.Xr usb 4
.Sh HISTORY
The
.Nm
driver
appeared in
.Nx 1.4 .
Support for the
.Dv USB_GET_DEVICEINFO
and
.Dv USB_GET_STRING_DESC
ioctls appeared in
.Nx 2.0 .