201 lines
5.4 KiB
Groff
201 lines
5.4 KiB
Groff
.\"
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.\" Copyright (c) 2014 Rui Paulo
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd July 1, 2015
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.Dt GPIO 3
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.Os
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.Sh NAME
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.Nm gpio_open ,
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.Nm gpio_close
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.Nd "library to handle GPIO pins"
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.Sh LIBRARY
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.Lb libgpio
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.Sh SYNOPSIS
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.In sys/types.h
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.In libgpio.h
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.Ft "gpio_handle_t"
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.Fn gpio_open "unsigned int unit"
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.Ft "gpio_handle_t"
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.Fn gpio_open_device "const char *device"
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.Ft void
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.Fn gpio_close "gpio_handle_t handle"
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.Ft int
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.Fn gpio_pin_list "gpio_handle_t handle" "gpio_config_t **pcfgs"
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.Ft int
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.Fn gpio_pin_config "gpio_handle_t handle" "gpio_config_t *cfg"
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.Ft int
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.Fn gpio_pin_set_name "gpio_handle_t handle" "gpio_pin_t pin" "char *name"
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.Ft int
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.Fn gpio_pin_set_flags "gpio_handle_t handle" "gpio_config_t *cfg"
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.Ft gpio_value_t
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.Fn gpio_pin_get "gpio_handle_t handle" "gpio_pin_t pin"
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.Ft int
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.Fn gpio_pin_set "gpio_handle_t handle" "gpio_pin_t pin" "gpio_value_t value"
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.Ft int
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.Fn gpio_pin_toggle "gpio_handle_t handle" "gpio_pin_t pin"
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.Ft int
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.Fn gpio_pin_low "gpio_handle_t handle" "gpio_pin_t pin"
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.Ft int
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.Fn gpio_pin_high "gpio_handle_t handle" "gpio_pin_t pin"
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.Ft int
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.Fn gpio_pin_input "gpio_handle_t handle" "gpio_pin_t pin"
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.Ft int
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.Fn gpio_pin_output "gpio_handle_t handle" "gpio_pin_t pin"
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.Ft int
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.Fn gpio_pin_opendrain "gpio_handle_t handle" "gpio_pin_t pin"
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.Ft int
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.Fn gpio_pin_pushpull "gpio_handle_t handle" "gpio_pin_t pin"
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.Ft int
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.Fn gpio_pin_tristate "gpio_handle_t handle" "gpio_pin_t pin"
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.Ft int
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.Fn gpio_pin_pullup "gpio_handle_t handle" "gpio_pin_t pin"
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.Ft int
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.Fn gpio_pin_pulldown "gpio_handle_t handle" "gpio_pin_t pin"
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.Ft int
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.Fn gpio_pin_invin "gpio_handle_t handle" "gpio_pin_t pin"
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.Ft int
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.Fn gpio_pin_invout "gpio_handle_t handle" "gpio_pin_t pin"
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.Ft int
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.Fn gpio_pin_pulsate "gpio_handle_t handle" "gpio_pin_t pin"
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.Sh DESCRIPTION
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The
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.Nm libgpio
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library provides an interface to configure GPIO pins.
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The library operates with a
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.Ft gpio_handle_t
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opaque type which can be created with
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.Fn gpio_open
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or
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.Fn gpio_open_device .
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When no more GPIO operations are needed, this handle can be destroyed
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with
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.Fn gpio_close .
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.Pp
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To get a list of all available pins, one can call
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.Fn gpio_pin_list .
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This function takes a pointer to a
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.Ft gpio_config_t
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which is dynamically allocated.
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This pointer should be freed with
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.Xr free 3
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when it is no longer necessary.
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.Pp
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The function
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.Fn gpio_pin_config
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retrieves the current configuration of a pin.
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The pin number should be passed in via the
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.Ft g_pin
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variable which is part of the
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.Ft gpio_config_t
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structure.
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.Pp
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The function
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.Fn gpio_pin_set_name
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sets the name used to describe a pin.
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.Pp
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The function
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.Fn gpio_pin_set_flags
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configures a pin with the flags passed in by the
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.Ft gpio_config_t
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structure.
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The pin number should also be passed in through the
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.Ft g_pin
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variable.
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All other structure members will be ignored by this function.
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The list of flags can be found in
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.Pa /usr/include/sys/gpio.h .
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.Pp
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The get or set the state of a GPIO pin, the functions
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.Fn gpio_pin_get
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and
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.Fn gpio_pin_set
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are available, respectively.
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To toggle the state, use
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.Fn gpio_pin_toggle .
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.Pp
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The functions
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.Fn gpio_pin_low
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and
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.Fn gpio_pin_high
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are wrappers around
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.Fn gpio_pin_set .
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.Pp
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The functions
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.Fn gpio_pin_input ,
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.Fn gpio_pin_output ,
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.Fn gpio_pin_opendrain ,
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.Fn gpio_pin_pushpull ,
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.Fn gpio_pin_tristate ,
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.Fn gpio_pin_pullup ,
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.Fn gpio_pin_pulldown ,
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.Fn gpio_pin_invin ,
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.Fn gpio_pin_invout
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and
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.Fn gpio_pin_pulsate
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are wrappers around
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.Fn gpio_pin_set_flags .
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.Sh EXAMPLES
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The following example shows how to configure pin 16 as output and then
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drive it high:
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.Bd -literal
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#include <sys/types.h>
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#include <err.h>
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#include <libgpio.h>
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gpio_handle_t handle;
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handle = gpio_open(0);
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if (handle == GPIO_INVALID_HANDLE)
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err(1, "gpio_open failed");
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gpio_pin_output(handle, 16);
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gpio_pin_high(handle, 16);
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gpio_close(handle);
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.Ed
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.Pp
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The following example shows how to get a configuration of a pin:
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.Bd -literal
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gpio_config_t cfg;
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cfg.g_pin = 32;
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gpio_pin_config(handle, &cfg);
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.Ed
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.Pp
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The structure will contain the name of the pin and its flags.
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.Sh SEE ALSO
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.Xr gpiobus 4 ,
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.Xr gpioctl 8
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.Sh HISTORY
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The
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.Nm libgpio
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library first appeared in
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.Fx 11.0 .
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.Sh AUTHORS
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The
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.Nm libgpio
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library was implemented by
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.An Rui Paulo Aq Mt rpaulo@FreeBSD.org .
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