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GPIOIIC(4)                 Kernel Interfaces Manual                 GPIOIIC(4)

     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

     gpio(4), iic(4), intro(4)

     The gpioiic driver first appeared in OpenBSD 3.9 and NetBSD 5.0.

     The gpioiic driver was written by Alexander Yurchenko
     <grangeATopenbsd.org> and was ported to NetBSD by Marc Balmer

     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.

NetBSD 6.1.5                    October 2, 2011                   NetBSD 6.1.5