freebsd-nq/share/man/man4/uhid.4

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.Dd July 1, 2018
.Dt UHID 4
.Os
.Sh NAME
.Nm uhid
.Nd USB generic HID support
.Sh SYNOPSIS
To compile this driver into the kernel,
place the following line in your
kernel configuration file:
.Bd -ragged -offset indent
.Cd "device uhid"
.Ed
.Pp
Alternatively, to load the driver as a
module at boot time, place the following line in
.Xr loader.conf 5 :
.Bd -literal -offset indent
uhid_load="YES"
.Ed
.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
The device handles the following
.Xr ioctl 2
calls:
.Bl -tag -width indent
.It Dv USB_GET_REPORT_ID Pq Vt int
Get the report identifier used by this HID report.
.It Dv USB_GET_REPORT_DESC Pq Vt "struct usb_gen_descriptor"
Get the HID report descriptor.
Copies a maximum of
.Va ugd_maxlen
bytes of the report descriptor data into the memory
specified by
.Va ugd_data .
Upon return
.Va ugd_actlen
is set to the number of bytes copied.
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_gen_descriptor {
	void   *ugd_data;
	uint16_t ugd_maxlen;
	uint16_t ugd_actlen;
	uint8_t	ugd_report_type;
	...
};
.Ed
.It Dv USB_SET_IMMED Pq Vt 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 Pq Vt "struct usb_gen_descriptor"
Get a report from the device without waiting for data on
the interrupt pipe.
Copies a maximum of
.Va ugd_maxlen
bytes of the report data into the memory specified by
.Va ugd_data .
Upon return
.Va ugd_actlen
is set to the number of bytes copied.
The
.Va ugd_report_type
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.
.It Dv USB_SET_REPORT Pq Vt "struct usb_gen_descriptor"
Set a report in the device.
The
.Va ugd_report_type
field indicates which report is to be set.
It should be
.Dv UHID_INPUT_REPORT ,
.Dv UHID_OUTPUT_REPORT ,
or
.Dv UHID_FEATURE_REPORT .
The value of the report is specified by the
.Va ugd_data
and the
.Va ugd_maxlen
fields.
This call may fail if the device does not support this feature.
.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
to send data to the device.
Data should be written in chunks of the
size prescribed by the report descriptor.
.Sh SYSCTL VARIABLES
The following variables are available as both
.Xr sysctl 8
variables and
.Xr loader 8
tunables:
.Bl -tag -width indent
.It Va hw.usb.uhid.debug
Debug output level, where 0 is debugging disabled and larger values increase
debug message verbosity.
Default is 0.
.Sh FILES
.Bl -tag -width ".Pa /dev/uhid?"
.It Pa /dev/uhid?
.El
.Sh SEE ALSO
.Xr usbhidctl 1 ,
.Xr usb 4
.Sh HISTORY
The
.Nm
driver
appeared in
.Nx 1.4 .
This manual page was adopted from
.Nx
by
.An Tom Rhodes Aq Mt trhodes@FreeBSD.org
in April 2002.