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/*
* The Rin Library – gpio module
*
* Copyright (C) 2016 Gediminas Jakutis
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; version 2.1
* of the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
*/
#include "rin/gpio.h"
#include "gpio_private.h"
unsigned int rin_gpio_open(const unsigned int num, const enum rin_gpiotype type)
{
struct stat st;
struct timespec grace = { 0, 1 * 1000 * 1000 }; /* 1 ms */
char buf[48] = { 0 };
int fd;
unsigned int timeout;
init();
if (type == rin_gpio_closed || !rin_gpio_pin_exists(num) || gpio[num].type != rin_gpio_closed) {
return 1;
}
fd = open("/sys/class/gpio/export", O_WRONLY | O_DSYNC);
sprintf(buf, "%u", num);
write(fd, buf, strlen(buf));
close(fd);
sprintf(buf, "/sys/class/gpio/gpio%u/direction", num);
timeout = 500; /* 500 ms, if it takes longer, something ain't right. */
while (stat(buf, &st)) {
nanosleep(&grace, NULL);
if (!(--timeout)) {
return 1;
}
}
fd = open(buf, O_WRONLY | O_DSYNC);
if (type == rin_gpio_in) {
write(fd, "in", 2);
} else {
write(fd, "out", 3);
}
close(fd);
gpio[num].type = type;
sprintf(buf, "/sys/class/gpio/gpio%u/value", num);
if (type == rin_gpio_in) {
gpio[num].fd = open(buf, O_RDONLY);
} else {
gpio[num].fd = open(buf, O_WRONLY);
}
return 0;
}
unsigned int rin_gpio_close(const unsigned int num)
{
char buf[32] = { 0 };
struct stat st;
int fd;
init();
sprintf(buf, "/sys/class/gpio/gpio%u", num);
if (stat(buf, &st)) {
return 0;
}
close(gpio[num].fd);
gpio[num].fd = -1;
fd = open("/sys/class/gpio/unexport", O_WRONLY);
sprintf(buf, "%u", num);
write(fd, buf, strlen(buf));
close(fd);
gpio[num].type = rin_gpio_closed;
return 0;
}
unsigned int rin_gpio_setval(const unsigned int num, const unsigned int val)
{
char buf[8] = { 0 };
init();
if (!rin_gpio_pin_exists(num) || gpio[num].type != rin_gpio_out) {
return 1;
}
sprintf(buf, "%u", val);
lseek(gpio[num].fd, 0, SEEK_SET);
write(gpio[num].fd, buf, strlen(buf));
return 0;
}
unsigned int rin_gpio_readval(const unsigned int num, unsigned int * const val)
{
init();
if (!rin_gpio_pin_exists(num) || gpio[num].type != rin_gpio_in) {
exit(EXIT_FAILURE);
}
lseek(gpio[num].fd, 0, SEEK_SET);
read(gpio[num].fd, val, 1);
if (*val >= '0') {
*val -= '0';
}
return 0;
}
/*
* right now is rpi V1 specific, should be rewritten when/if we support
* other platforms.
*/
unsigned int rin_gpio_pin_exists(const unsigned int pin)
{
switch (pin) {
case 2:
case 3:
case 4:
case 7:
case 8:
case 9:
case 10:
case 11:
case 14:
case 15:
case 17:
case 18:
case 22:
case 23:
case 24:
case 25:
return 1;
default:
return 0;
}
}
/*
* in case we ever support hardware other than the V1 Raspberry,
* we need this to get the pin usable pin count
*/
unsigned int rin_gpio_get_pincount(void)
{
return 16;
}
static void init(void)
{
size_t i;
static unsigned int firstrun = 1;
if (firstrun) {
firstrun = 0;
for (i = 0; i < gpio_count; ++i) {
gpio[i].num = i;
gpio[i].type = rin_gpio_closed;
gpio[i].fd = -1;
}
}
}
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