1.\" Copyright (c) 2013, Luiz Otavio O Souza <loos@FreeBSD.org> 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 13.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 14.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 16.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 17.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 18.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 19.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 20.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 21.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 22.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 23.\" SUCH DAMAGE. 24.\" 25.\" $FreeBSD$ 26.\" 27.Dd November 5, 2013 28.Dt GPIOIIC 4 29.Os 30.Sh NAME 31.Nm gpioiic 32.Nd GPIO I2C bit-banging device driver 33.Sh SYNOPSIS 34.Cd "device gpio" 35.Cd "device gpioiic" 36.Cd "device iic" 37.Cd "device iicbb" 38.Cd "device iicbus" 39.Sh DESCRIPTION 40The 41.Em gpioiic 42driver provides an IIC bit-banging interface using two GPIO pins for the 43SCL and SDA on the 44.Em gpiobus . 45.Nm 46implements an open colector kind of output, as recommended by the standard, 47when driving the pins on the 48.Em gpiobus , 49i.e, they are never switched to the logical value of '1', 50or they are '0' or simply open (Hi-Z/tri-state). 51So the pullup resistors are required so 52.Nm 53can work. 54.Pp 55On a hint based system, like 56.Li MIPS , these values are configureable for the 57.Nm gpioiic : 58.Bl -tag -width ".Va hint.gpioiic.%d.atXXX" 59.It Va hint.gpioiic.%d.at 60The gpiobus you are attaching to. 61Normally just gpiobus0. 62.It Va hint.gpioiic.%d.pins 63This is a bitmask of the pins on the 64.Em gpiobus 65that are to be used for SCLOCK and SDATA from the GPIO IIC 66bit-banging bus. 67To configure pin 0 and 7, use the bitmask of 6810000001 and convert it to a hexadecimal value of 0x0081. 69Please note that this mask should only ever have two bits set 70(any others bits - i.e., pins - will be ignored). 71.It Va hint.gpioiic.%d.scl 72Indicates which bit in the 73.Va hint.gpioiic.%d.pins 74should be used as the SCLOCK 75source. 76.It Va hint.gpioiic.%d.sda 77Indicates which bit in the 78.Va hint.gpioiic.%d.pins 79should be used as the SDATA 80source. 81.El 82.Sh SEE ALSO 83.Xr gpio 4 , 84.Xr gpioled 4 , 85.Xr iic 4 , 86.Xr iicbb 4 , 87.Xr iicbus 4 88.Sh HISTORY 89The 90.Nm 91manual page first appeared in 92.Fx 11.0 . 93.Sh AUTHORS 94This 95manual page was written by 96.An Luiz Otavio O Souza . 97