gpiolock —
support for multi-position keylocks attached to GPIO pins
gpiolock* at gpio? offset ? mask ?
gpiolock* at gpio?
The gpiolock driver allows connecting of multi-position
  keylocks over GPIO pins. The keylock driver registers with an in-kernel
  keylock supporting system and provides
  kauth(9) support through an
  experimental security model. The keylock state can be queried using the
  hw.keylock sysctl variables. Only locks with 2-4 positions are currently
  supported. The pin number is specified in the kernel configuration with the
  offset locator. The mask locator
  denotes the pins used for the lock (minimum 2, maximum 4 pins are used). The
  offset and mask can also be
  specified when gpiolock is attached at runtime using
  the GPIOATTACH
  ioctl(2) on the
  gpio(4) device.
The gpiolock driver first appeared in
  NetBSD 6.0.
The gpiolock driver was written by Marc
  Balmer
  <marc@msys.ch>.