2009-08-09 12:44:30 +04:00
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.\" $NetBSD: gpioiic.4,v 1.2 2009/08/09 08:44:30 wiz Exp $
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2009-08-09 12:20:53 +04:00
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.\" $OpenBSD: gpioiic.4,v 1.6 2008/11/24 15:30:21 jmc Exp $
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.\"
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.\" Copyright (c) 2006 Alexander Yurchenko <grange@openbsd.org>
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.\"
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.\" Permission to use, copy, modify, and distribute this software for any
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.\" purpose with or without fee is hereby granted, provided that the above
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.\" copyright notice and this permission notice appear in all copies.
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.\"
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.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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.\"
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.Dd August 8, 2009
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.Dt GPIOIIC 4
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.Os
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.Sh NAME
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.Nm gpioiic
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.Nd GPIO I2C controller
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.Sh SYNOPSIS
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.Cd "gpioiic* at gpio? offset 0 mask 0x3"
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.Cd "gpioiic* at gpio?"
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.Cd "iic* at gpioiic?"
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.Sh DESCRIPTION
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The
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.Nm
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driver allows bit-banging an I2C bus as a master using two GPIO pins.
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The first pin is used as a serial data (SDA) signal and the second as
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a serial clock (SCL).
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Both GPIO pins must be able to drive an output and the SDA pin must be
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also able to read an input.
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.Pp
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The pins can be specified in the kernel configuration with the
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.Ar offset
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and the
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.Ar mask
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locators.
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The
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.Ar offset
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and
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.Ar mask
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can also be specified when
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.Nm
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is attached at runtime using the
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.Dv GPIOATTACH
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.Xr ioctl 2
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on the
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.Xr gpio 4
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device.
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Each bit in the
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.Ar mask
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locator defines one pin; the pin number is calculated as an addition of
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the bit position and the
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.Ar offset
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locator.
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For example,
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.Ar offset 17
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and
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.Ar mask 0x5
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defines pin numbers 17 and 19.
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.Sh SEE ALSO
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.Xr gpio 4 ,
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.Xr iic 4 ,
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.Xr intro 4
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.Sh HISTORY
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The
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.Nm
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driver first appeared in
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.Ox 3.9
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and
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.Nx 5.0 .
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.Sh AUTHORS
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.An -nosplit
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The
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.Nm
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driver was written by
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.An Alexander Yurchenko Aq grange@openbsd.org
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2009-08-09 12:44:30 +04:00
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and was ported to
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2009-08-09 12:20:53 +04:00
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.Nx
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by
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.An Marc Balmer Aq marc@msys.ch .
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2009-08-09 12:44:30 +04:00
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.Sh CAVEATS
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A
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.Nm
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device can not be detached from the
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.Xr gpio 4
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bus at runtime due to the fact that
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.Xr iic 4
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busses can not detach once attached.
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