1.\" $OpenBSD: gpioiic.4,v 1.6 2008/11/24 15:30:21 jmc Exp $ 2.\" 3.\" Copyright (c) 2006 Alexander Yurchenko <grange@openbsd.org> 4.\" 5.\" Permission to use, copy, modify, and distribute this software for any 6.\" purpose with or without fee is hereby granted, provided that the above 7.\" copyright notice and this permission notice appear in all copies. 8.\" 9.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16.\" 17.Dd $Mdocdate: November 24 2008 $ 18.Dt GPIOIIC 4 19.Os 20.Sh NAME 21.Nm gpioiic 22.Nd GPIO I2C controller 23.Sh SYNOPSIS 24.Cd "gpioiic* at gpio? offset 0 mask 0x3" 25.Cd "gpioiic* at gpio?" 26.Cd "iic* at gpioiic?" 27.Sh DESCRIPTION 28The 29.Nm 30driver allows bit-banging an I2C bus as a master using two GPIO pins. 31The first pin is used as a serial data (SDA) signal and the second as 32a serial clock (SCL). 33Both GPIO pins must be able to drive an output and the SDA pin must be 34also able to read an input. 35.Pp 36The pins can be specified in the kernel configuration with the 37.Ar offset 38and the 39.Ar mask 40locators. 41The 42.Ar offset 43and 44.Ar mask 45can also be specified when 46.Nm 47is attached at runtime using the 48.Dv GPIOATTACH 49.Xr ioctl 2 50on the 51.Xr gpio 4 52device. 53Each bit in the 54.Ar mask 55locator defines one pin; the pin number is calculated as an addition of 56the bit position and the 57.Ar offset 58locator. 59For example, 60.Ar offset 17 61and 62.Ar mask 0x5 63defines pin numbers 17 and 19. 64.Sh SEE ALSO 65.Xr gpio 4 , 66.Xr iic 4 , 67.Xr intro 4 68.Sh HISTORY 69The 70.Nm 71driver first appeared in 72.Ox 3.9 . 73.Sh AUTHORS 74.An -nosplit 75The 76.Nm 77driver was written by 78.An Alexander Yurchenko Aq grange@openbsd.org . 79