gpioiic —
GPIO I2C controller
gpioiic* at gpio? offset 0 mask 0x3 flag 0x0
gpioiic* at gpio?
iic* at gpioiic?
The gpioiic driver allows bit-banging an I2C bus as a
  master using two GPIO pins. By default the first pin is used as a serial data
  (SDA) signal and the second as a serial clock (SCL). If the flag locator is
  set to 0x01, the order of the SDA and SCL signals is reversed. Both GPIO pins
  must be able to drive an output and the SDA pin must be also able to read an
  input.
The pins can be specified in the kernel configuration with the
    offset and the mask locators.
    The offset and mask can also be
    specified when gpioiic is attached at runtime using
    the GPIOATTACH
    ioctl(2) on the
    gpio(4) device. Each bit in the
    mask locator defines one pin; the pin number is
    calculated as an addition of the bit position and the
    offset locator. For example, offset
    17 and mask 0x5 defines pin numbers 17 and
  19.
The gpioiic driver first appeared in
  OpenBSD 3.9 and NetBSD 5.0.
A gpioiic device can not be detached from the
  gpio(4) bus at runtime due to the
  fact that iic(4) busses can not
  detach once attached.