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gpio.c
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gpio.c
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/* Copyright (c) 2011, RidgeRun
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the RidgeRun.
* 4. Neither the name of the RidgeRun nor the
* names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY RIDGERUN ''AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL RIDGERUN BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include "gpio.h"
#define MAX_BUF 100
/****************************************************************
* gpio_open_value_file
****************************************************************/
int gpio_open_file( unsigned int gpio, const char* file)
{
char path[ MAX_BUF];
(void) snprintf( path, sizeof( path), "/sys/class/gpio/gpio%d/%s", gpio, file);
int fd = open( path, O_RDONLY | O_NONBLOCK );
if (fd < 0) {
perror( "gpio_open_value_file - ");
}
return fd;
}
/****************************************************************
* gpio_write_value_to_file
****************************************************************/
int gpio_write_value_to_file( const char* file, const char* value)
{
char path[ MAX_BUF];
(void) snprintf( path, sizeof( path), "/sys/class/gpio/%s", file);
int fd = open( path, O_WRONLY);
if (fd < 0) {
perror( "gpio_set failed");
return fd;
}
// Include terminating null in write!
write( fd, value, strlen( value) + 1);
close( fd);
return 0;
}
/****************************************************************
* gpio_write_value_to_pin_file
****************************************************************/
/*
* Write 'value' to 'file' in the directory subtree for 'gpio'
*/
int gpio_write_value_to_pin_file( unsigned int gpio, const char* file, const char* value)
{
char gpio_file[ MAX_BUF];
(void) snprintf( gpio_file, sizeof( gpio_file), "/gpio%d/%s", gpio, file);
return gpio_write_value_to_file( gpio_file, value);
}
int gpio_write_int_value_to_file( const char* file, int value)
{
char buffer[ 8];
(void) snprintf( buffer, sizeof( buffer), "%d", value);
return gpio_write_value_to_file( file, buffer);
}