.\"	$OpenBSD: gpioiic.4,v 1.2 2006/01/14 12:28:44 jmc Exp $
.\"
.\" Copyright (c) 2006 Alexander Yurchenko <grange@openbsd.org>
.\"
.\" Permission to use, copy, modify, and distribute this software for any
.\" purpose with or without fee is hereby granted, provided that the above
.\" copyright notice and this permission notice appear in all copies.
.\"
.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
.\"
.Dd January 14, 2006
.Dt GPIOIIC 4
.Os
.Sh NAME
.Nm gpioiic
.Nd I2C bus bit-banging through GPIO pins
.Sh SYNOPSIS
.Cd "gpioiic* at gpio? offset 0 mask 0x3"
.Cd "iic* at gpioiic?"
.Sh DESCRIPTION
The
.Nm
driver allows bit-banging an I2C bus as a master using two GPIO pins.
The first pin is used as a serial data (SDA) signal and the second as
a serial clock (SCL).
Both GPIO pins must be able to drive an output and the SDA pin must be
also able to read an input.
.Pp
The pins are specified in the kernel configuration with the
.Ar offset
and the
.Ar mask
locators.
Each bit in the
.Ar mask
locator defines one pin; the pin number is calculated as an addition of
the bit position and the
.Ar offset
locator.
For example,
.Ar offset 17
and
.Ar mask 0x5
defines pin numbers 17 and 19.
.Sh SEE ALSO
.Xr gpio 4 ,
.Xr iic 4 ,
.Xr intro 4
.Sh HISTORY
The
.Nm
driver first appeared in
.Ox 3.9 .
.Sh AUTHORS
.An -nosplit
The
.Nm
driver was written by
.An Alexander Yurchenko Aq grange@openbsd.org .