.\"
.\" Copyright (c) 2014 Rui Paulo
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.\"
.Dd July 1, 2015
.Dt GPIO 3
.Os
.Sh NAME
.Nm gpio_open ,
.Nm gpio_close
.Nd "library to handle GPIO pins"
.Sh LIBRARY
.Lb libgpio
.Sh SYNOPSIS
.In sys/types.h
.In libgpio.h
.Ft "gpio_handle_t"
.Fn gpio_open "unsigned int unit"
.Ft "gpio_handle_t"
.Fn gpio_open_device "const char *device"
.Ft void
.Fn gpio_close "gpio_handle_t handle"
.Ft int
.Fn gpio_pin_list "gpio_handle_t handle" "gpio_config_t **pcfgs"
.Ft int
.Fn gpio_pin_config "gpio_handle_t handle" "gpio_config_t *cfg"
.Ft int
.Fn gpio_pin_set_name "gpio_handle_t handle" "gpio_pin_t pin" "char *name"
.Ft int
.Fn gpio_pin_set_flags "gpio_handle_t handle" "gpio_config_t *cfg"
.Ft gpio_value_t
.Fn gpio_pin_get "gpio_handle_t handle" "gpio_pin_t pin"
.Ft int
.Fn gpio_pin_set "gpio_handle_t handle" "gpio_pin_t pin" "gpio_value_t value"
.Ft int
.Fn gpio_pin_toggle "gpio_handle_t handle" "gpio_pin_t pin"
.Ft int
.Fn gpio_pin_low "gpio_handle_t handle" "gpio_pin_t pin"
.Ft int
.Fn gpio_pin_high "gpio_handle_t handle" "gpio_pin_t pin"
.Ft int
.Fn gpio_pin_input "gpio_handle_t handle" "gpio_pin_t pin"
.Ft int
.Fn gpio_pin_output "gpio_handle_t handle" "gpio_pin_t pin"
.Ft int
.Fn gpio_pin_opendrain "gpio_handle_t handle" "gpio_pin_t pin"
.Ft int
.Fn gpio_pin_pushpull "gpio_handle_t handle" "gpio_pin_t pin"
.Ft int
.Fn gpio_pin_tristate "gpio_handle_t handle" "gpio_pin_t pin"
.Ft int
.Fn gpio_pin_pullup "gpio_handle_t handle" "gpio_pin_t pin"
.Ft int
.Fn gpio_pin_pulldown "gpio_handle_t handle" "gpio_pin_t pin"
.Ft int
.Fn gpio_pin_invin "gpio_handle_t handle" "gpio_pin_t pin"
.Ft int
.Fn gpio_pin_invout "gpio_handle_t handle" "gpio_pin_t pin"
.Ft int
.Fn gpio_pin_pulsate "gpio_handle_t handle" "gpio_pin_t pin"
.Sh DESCRIPTION
The
.Nm libgpio
library provides an interface to configure GPIO pins.
The library operates with a
.Ft gpio_handle_t
opaque type which can be created with
.Fn gpio_open
or
.Fn gpio_open_device .
When no more GPIO operations are needed, this handle can be destroyed
with
.Fn gpio_close .
.Pp
To get a list of all available pins, one can call
.Fn gpio_pin_list .
This function takes a pointer to a
.Ft gpio_config_t
which is dynamically allocated.
This pointer should be freed with
.Xr free 3
when it is no longer necessary.
.Pp
The function
.Fn gpio_pin_config
retrieves the current configuration of a pin.
The pin number should be passed in via the
.Ft g_pin
variable which is part of the
.Ft gpio_config_t
structure.
.Pp
The function
.Fn gpio_pin_set_name
sets the name used to describe a pin.
.Pp
The function
.Fn gpio_pin_set_flags
configures a pin with the flags passed in by the
.Ft gpio_config_t
structure.
The pin number should also be passed in through the
.Ft g_pin
variable.
All other structure members will be ignored by this function.
The list of flags can be found in
.Pa /usr/include/sys/gpio.h .
.Pp
The get or set the state of a GPIO pin, the functions
.Fn gpio_pin_get
and
.Fn gpio_pin_set
are available, respectively.
To toggle the state, use
.Fn gpio_pin_toggle .
.Pp
The functions
.Fn gpio_pin_low
and
.Fn gpio_pin_high
are wrappers around
.Fn gpio_pin_set .
.Pp
The functions
.Fn gpio_pin_input ,
.Fn gpio_pin_output ,
.Fn gpio_pin_opendrain ,
.Fn gpio_pin_pushpull ,
.Fn gpio_pin_tristate ,
.Fn gpio_pin_pullup ,
.Fn gpio_pin_pulldown ,
.Fn gpio_pin_invin ,
.Fn gpio_pin_invout
and
.Fn gpio_pin_pulsate
are wrappers around
.Fn gpio_pin_set_flags .
.Sh EXAMPLES
The following example shows how to configure pin 16 as output and then
drive it high:
.Bd -literal
#include <sys/types.h>
#include <err.h>
#include <libgpio.h>

gpio_handle_t handle;

handle = gpio_open(0);
if (handle == GPIO_INVALID_HANDLE)
	err(1, "gpio_open failed");
gpio_pin_output(handle, 16);
gpio_pin_high(handle, 16);
gpio_close(handle);
.Ed
.Pp
The following example shows how to get a configuration of a pin:
.Bd -literal
gpio_config_t cfg;

cfg.g_pin = 32;
gpio_pin_config(handle, &cfg);
.Ed
.Pp
The structure will contain the name of the pin and its flags.
.Sh SEE ALSO
.Xr gpiobus 4 ,
.Xr gpioctl 8
.Sh HISTORY
The
.Nm libgpio
library first appeared in
.Fx 11.0 .
.Sh AUTHORS
The
.Nm libgpio
library was implemented by
.An Rui Paulo Aq Mt rpaulo@FreeBSD.org .