cd2827b367
Specifically: Support disabling specific pins on specific ports. Modification of TS7200 kernel config file for GPIO support. Documentatin for the current and improved GPIO interface (epgpio).
182 lines
4.0 KiB
Groff
182 lines
4.0 KiB
Groff
.\" $NetBSD: gpio.4,v 1.8 2009/02/27 03:13:55 kenh 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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.Cd "gpio* at epgpio?"
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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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