181 lines
4.0 KiB
Groff
181 lines
4.0 KiB
Groff
.\" $NetBSD: gpio.4,v 1.7 2008/04/29 14:07:36 cegger Exp $
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.\" $OpenBSD: gpio.4,v 1.5 2004/11/23 09:39:29 reyk Exp $
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.\"
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.\" Copyright (c) 2004 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 January 9, 2008
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.Dt GPIO 4
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.Os
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.Sh NAME
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.Nm gpio
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.Nd General Purpose Input/Output
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.Sh SYNOPSIS
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.Cd "gpio* at elansc?"
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.Cd "gpio* at gcscpcib?"
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.Cd "gpio* at gscpcib?"
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.Cd "gpio* at nsclpcsio?"
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.Cd "gpio* at ppbus?"
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.Pp
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.In sys/types.h
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.In sys/gpio.h
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.In sys/ioctl.h
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.Sh DESCRIPTION
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The
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.Nm
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device attaches to the
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.Tn GPIO
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controller and provides a uniform programming interface to its pins.
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.Pp
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Each
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.Tn GPIO
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controller with an attached
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.Nm
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device has an associated device file under the
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.Pa /dev
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directory, e.g.\&
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.Pa /dev/gpio0 .
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Access from userland is performed through
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.Xr ioctl 2
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calls on these devices.
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.Sh IOCTL INTERFACE
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The following structures and constants are defined in the
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.Aq Pa sys/gpio.h
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header file:
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.Pp
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.Bl -tag -width XXXX -compact
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.It Dv GPIOINFO (struct gpio_info)
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Returns information about the
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.Tn GPIO
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controller in the
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.Fa gpio_info
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structure:
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.Bd -literal
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struct gpio_info {
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int gpio_npins; /* total number of pins available */
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};
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.Ed
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.Pp
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.It Dv GPIOPINREAD (struct gpio_pin_op)
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Returns the input pin value in the
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.Fa gpio_pin_op
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structure:
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.Bd -literal
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struct gpio_pin_op {
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int gp_pin; /* pin number */
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int gp_value; /* value */
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};
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.Ed
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.Pp
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The
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.Fa gp_pin
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field must be set before calling.
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.Pp
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.It Dv GPIOPINWRITE (struct gpio_pin_op)
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Writes the output value to the pin.
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The value set in the
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.Fa gp_value
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field must be either
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.Dv GPIO_PIN_LOW
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(logical 0) or
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.Dv GPIO_PIN_HIGH
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(logical 1).
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On return, the
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.Fa gp_value
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field contains the old pin state.
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.Pp
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.It Dv GPIOPINTOGGLE (struct gpio_pin_op)
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Toggles the pin output value, i.e. changes it to the opposite.
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.Fa gp_value
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field is ignored and on return contains the old pin state.
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.Pp
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.It Dv GPIOPINCTL (struct gpio_pin_ctl)
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Changes pin configuration flags with the new ones provided in the
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.Fa gpio_pin_ctl
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structure:
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.Bd -literal
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struct gpio_pin_ctl {
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int gp_pin; /* pin number */
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int gp_caps; /* pin capabilities (read-only) */
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int gp_flags; /* pin configuration flags */
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};
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.Ed
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.Pp
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The
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.Fa gp_flags
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field is a combination of the following flags:
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.Pp
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.Bl -tag -width GPIO_PIN_OPENDRAIN -compact
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.It Dv GPIO_PIN_INPUT
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input direction
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.It Dv GPIO_PIN_OUTPUT
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output direction
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.It Dv GPIO_PIN_INOUT
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bi-directional
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.It Dv GPIO_PIN_OPENDRAIN
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open-drain output
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.It Dv GPIO_PIN_PUSHPULL
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push-pull output
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.It Dv GPIO_PIN_TRISTATE
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output disabled
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.It Dv GPIO_PIN_PULLUP
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internal pull-up enabled
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.It Dv GPIO_PIN_PULLDOWN
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internal pull-down enabled
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.It Dv GPIO_PIN_INVIN
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invert input
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.It Dv GPIO_PIN_INVOUT
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invert output
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.El
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.Pp
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Note that the
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.Tn GPIO
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controller
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may not support all of these flags.
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On return the
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.Fa gp_caps
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field contains flags that are supported.
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If no flags are specified, the pin configuration stays unchanged.
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.El
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.Sh FILES
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.Bl -tag -width "/dev/gpiou" -compact
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.It /dev/gpio Ns Ar u
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GPIO device unit
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.Ar u
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file.
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.El
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.Sh SEE ALSO
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.Xr ioctl 2 ,
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.Xr gpioctl 8
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.Sh HISTORY
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The
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.Nm
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device first appeared in
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.Ox 3.6
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and
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.Nx 4.0 .
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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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.Nm
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and was ported to
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.Nx
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by
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.An Jared D. McNeill Aq jmcneill@NetBSD.org .
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.Sh BUGS
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Event capabilities are not supported.
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