UHID(4) | Device Drivers Manual | UHID(4)

# NAME

`uhid` — USB generic HID support

# SYNOPSIS

`uhid* at uhidev?`

`#include <dev/usb/usb.h>`

# DESCRIPTION

The `uhid` driver provides support for all HID (Human Interface Device) interfaces in USB devices that do not have a special driver.

The device handles the following ioctl(2) calls:

`USB_GET_DEVICEINFO` struct usb_device_info *devinfo
  Get summarized information about the device.
`USB_GET_REPORT_ID` int *repid
  Get the report identifier used by this HID report.
`USB_GET_REPORT_DESC` struct usb_ctl_report_desc *repdesc
  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.

      struct usb_ctl_report_desc {
          int     ucrd_size;
          u_char  ucrd_data[1024];	/* filled data size will vary */
      };

`USB_GET_REPORT` struct usb_ctl_report *rep
  Get a report from the device without waiting for data on the interrupt pipe. The ucr_report field indicates which report is requested. It should be `UHID_INPUT_REPORT`, `UHID_OUTPUT_REPORT`, or `UHID_FEATURE_REPORT`.

      struct usb_ctl_report {
      	int	ucr_report;
      	u_char	ucr_data[1024];	/* filled data size will vary */
      };

`USB_SET_REPORT` struct usb_ctl_report *rep
  Set a report in the device. The `report` field indicates which report is to be set. It should be `UHID_INPUT_REPORT`, `UHID_OUTPUT_REPORT`, or `UHID_FEATURE_REPORT`.

The generic ioctls `FIONBIO` and `FIOASYNC` are supported by `uhid`.

Use read(2) to get data from the device. Data should be read in chunks of the size prescribed by the report descriptor.

Use write(2) to send data to the device. Equivalent to issuing an ioctl(2) `USB_SET_REPORT` request with the report set to `UHID_OUTPUT_REPORT`. Data should be written in chunks of the size prescribed by the report descriptor.

# FILES

/dev/uhid*

# ERRORS

If ioctl(2) fails, errno(2) is set to one of the following:

[`EIO`]
  The device could not fulfill a `USB_GET_REPORT` or `USB_SET_REPORT` request.
[`EINVAL`]
  The report specified by the ucr_report field in a `USB_GET_REPORT` or `USB_SET_REPORT` request was invalid.
[`ENOTTY`]
  Unrecognized command.

If read(2) fails, errno(2) is set to one of the following:

[`EIO`]
  The device has already been detached.
[`EWOULDBLOCK`]
  Non-blocking I/O was selected and no data were available.

If write(2) fails, errno(2) is set to one of the following:

[`EIO`]
  The device has already been detached or the same device does not have a corresponding output report.
[`EMSGSIZE`]
  The size of the supplied data exceeds the size of the output report.

# SEE ALSO

usbhidctl(1), usbhid(3), intro(4), uhidev(4), usb(4)

# HISTORY

The `uhid` driver appeared in OpenBSD 2.6.

September 15, 2021 | Debian