Interfaceshidraw

Interfaceshidraw is a term used to describe the Linux kernel’s HID raw interface, provided by the hidraw driver. This interface presents each HID device as a character device (typically /dev/hidrawN) and exposes raw HID reports to user-space applications. The key characteristic of interfaceshidraw is that it bypasses higher-level HID processing, delivering the exact report data as defined by the device’s HID report descriptor.

How it works: when a HID device is detected and not claimed by other HID subsystems, the hidraw driver binds to it and creates a corresponding /dev/hidrawN node. Applications can open this node to read input reports or write output/feature reports, depending on the device’s capabilities. A common usage pattern is to read raw input data for custom interpretation, debugging, or device development. Tools and libraries may also use ioctls to fetch the device’s HID descriptor or raw information such as bus type, vendor, and product identifiers.

Usage considerations: access to the hidraw interface usually requires appropriate permissions, which can be managed via system groups or udev rules. The data is binary and device-specific, so consuming it typically requires knowledge of the device’s report format. Not all HID devices support all report types, and some devices may be claimed by other kernel drivers, in which case the hidraw interface may not be available.

Relation to other interfaces: hidraw sits beside other HID interfaces such as hiddev and the evdev layer. While hidraw focuses on raw reports, evdev provides a higher-level event interface for input devices, and hiddev is an older, more feature-specific HID interface.

See also: HID (Human Interface Device), hidraw, /dev/hidraw*, evdev, HID ioctl interfaces.