86 lines
1.9 KiB
C
86 lines
1.9 KiB
C
#include <sys/types.h>
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#include <sys/stat.h>
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#include <string.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <time.h>
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#include <errno.h>
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#include <stdio.h> /* printf(), snprintf() */
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#include <stdlib.h> /* strtol(), exit() */
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#include <sys/types.h>
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#include <time.h>
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#include <errno.h>
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#include "gpiosysfs.h"
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static void writeToFile(const char *absoluteFileName, const char *contents) {
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int fd = open(absoluteFileName, O_WRONLY);
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if (-1 == fd) {
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fprintf(stderr, "Couldn't open %s for writing!\n", absoluteFileName);
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exit(1);
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}
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int contentsLength = strlen(contents);
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if (write(fd, contents, contentsLength) != contentsLength) {
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fprintf(stderr, "Failed to write entire value %s to %s!\n", contents, absoluteFileName);
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close(fd);
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exit(1);
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}
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close(fd);
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}
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void gpioSetup(const char *pin) {
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// TODO only export if not already exported...
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if (access("/sys/class/gpio/unexport",W_OK) == 0)
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writeToFile("/sys/class/gpio/unexport", pin);
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writeToFile("/sys/class/gpio/export", pin);
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char buf[33];
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struct stat statBuf;
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int pinExported = -1;
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sprintf(buf, "/sys/class/gpio/gpio%s/direction", pin);
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// May have to briefly wait for OS to make symlink!
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while (pinExported != 0) {
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msleep(1000);
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pinExported = stat(buf, &statBuf);
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}
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writeToFile(buf, "out");
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}
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void gpioCleanup(const char *pin) {
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writeToFile("/sys/class/gpio/unexport", pin);
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}
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void gpioWrite(const char *pin, const char *val) {
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char buf[29];
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sprintf(buf, "/sys/class/gpio/gpio%s/value", pin);
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writeToFile(buf, val);
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}
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/* msleep(): Sleep for the requested number of milliseconds. */
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int msleep(long msec)
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{
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struct timespec ts;
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int res;
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if (msec < 0)
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{
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errno = EINVAL;
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return -1;
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}
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ts.tv_sec = msec / 1000;
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ts.tv_nsec = (msec % 1000) * 1000000;
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do {
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res = nanosleep(&ts, &ts);
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} while (res && errno == EINTR);
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return res;
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}
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