initial commit of the code

gpioIrq.c

@@ -0,0 +1,254 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <poll.h>
+
+ /****************************************************************
+ * Constants
+ ****************************************************************/
+
+#define SYSFS_GPIO_DIR "/sys/class/gpio"
+#define POLL_TIMEOUT (3 * 1000) /* 3 seconds */
+#define MAX_BUF 64
+
+/****************************************************************
+ * gpio_export
+ ****************************************************************/
+int gpio_export(unsigned int gpio)
+{
+	int fd, len;
+	char buf[MAX_BUF];
+
+	fd = open(SYSFS_GPIO_DIR "/export", O_WRONLY);
+	if (fd < 0) {
+		perror("gpio/export");
+		return fd;
+	}
+
+	len = snprintf(buf, sizeof(buf), "%d", gpio);
+	write(fd, buf, len);
+	close(fd);
+
+	return 0;
+}
+
+/****************************************************************
+ * gpio_unexport
+ ****************************************************************/
+int gpio_unexport(unsigned int gpio)
+{
+	int fd, len;
+	char buf[MAX_BUF];
+
+	fd = open(SYSFS_GPIO_DIR "/unexport", O_WRONLY);
+	if (fd < 0) {
+		perror("gpio/export");
+		return fd;
+	}
+
+	len = snprintf(buf, sizeof(buf), "%d", gpio);
+	write(fd, buf, len);
+	close(fd);
+	return 0;
+}
+
+/****************************************************************
+ * gpio_set_dir
+ ****************************************************************/
+int gpio_set_dir(unsigned int gpio, unsigned int out_flag)
+{
+	int fd, len;
+	char buf[MAX_BUF];
+
+	len = snprintf(buf, sizeof(buf), SYSFS_GPIO_DIR  "/gpio%d/direction", gpio);
+
+	fd = open(buf, O_WRONLY);
+	if (fd < 0) {
+		perror("gpio/direction");
+		return fd;
+	}
+
+	if (out_flag)
+		write(fd, "out", 4);
+	else
+		write(fd, "in", 3);
+
+	close(fd);
+	return 0;
+}
+
+/****************************************************************
+ * gpio_set_value
+ ****************************************************************/
+int gpio_set_value(unsigned int gpio, unsigned int value)
+{
+	int fd, len;
+	char buf[MAX_BUF];
+
+	len = snprintf(buf, sizeof(buf), SYSFS_GPIO_DIR "/gpio%d/value", gpio);
+
+	fd = open(buf, O_WRONLY);
+	if (fd < 0) {
+		perror("gpio/set-value");
+		return fd;
+	}
+
+	if (value)
+		write(fd, "1", 2);
+	else
+		write(fd, "0", 2);
+
+	close(fd);
+	return 0;
+}
+
+/****************************************************************
+ * gpio_get_value
+ ****************************************************************/
+int gpio_get_value(unsigned int gpio, unsigned int *value)
+{
+	int fd, len;
+	char buf[MAX_BUF];
+	char ch;
+
+	len = snprintf(buf, sizeof(buf), SYSFS_GPIO_DIR "/gpio%d/value", gpio);
+
+	fd = open(buf, O_RDONLY);
+	if (fd < 0) {
+		perror("gpio/get-value");
+		return fd;
+	}
+
+	read(fd, &ch, 1);
+
+	if (ch != '0') {
+		*value = 1;
+	} else {
+		*value = 0;
+	}
+
+	close(fd);
+	return 0;
+}
+
+
+/****************************************************************
+ * gpio_set_edge
+ ****************************************************************/
+
+int gpio_set_edge(unsigned int gpio, char *edge)
+{
+	int fd, len;
+	char buf[MAX_BUF];
+
+	len = snprintf(buf, sizeof(buf), SYSFS_GPIO_DIR "/gpio%d/edge", gpio);
+
+	fd = open(buf, O_WRONLY);
+	if (fd < 0) {
+		perror("gpio/set-edge");
+		return fd;
+	}
+
+	write(fd, edge, strlen(edge) + 1);
+	close(fd);
+	return 0;
+}
+
+/****************************************************************
+ * gpio_fd_open
+ ****************************************************************/
+
+int gpio_fd_open(unsigned int gpio)
+{
+	int fd, len;
+	char buf[MAX_BUF];
+
+	len = snprintf(buf, sizeof(buf), SYSFS_GPIO_DIR "/gpio%d/value", gpio);
+
+	fd = open(buf, O_RDONLY | O_NONBLOCK );
+	if (fd < 0) {
+		perror("gpio/fd_open");
+	}
+	return fd;
+}
+
+/****************************************************************
+ * gpio_fd_close
+ ****************************************************************/
+
+int gpio_fd_close(int fd)
+{
+	return close(fd);
+}
+
+/****************************************************************
+ * Main
+ ****************************************************************/
+int main(int argc, char **argv, char **envp)
+{
+	struct pollfd fdset[2];
+	int nfds = 2;
+	int gpio_fd, timeout, rc;
+	char *buf[MAX_BUF];
+	unsigned int gpio;
+	int len;
+	int val;
+
+
+
+	if (argc < 2) {
+		printf("Usage: gpioIrq <gpio-pin>\n\n");
+		printf("Waits for a change in the GPIO pin voltage level or input on stdin\n");
+		exit(-1);
+	}
+
+	gpio = atoi(argv[1]);
+
+	gpio_export(gpio);
+	gpio_set_dir(gpio, 0);
+	gpio_set_edge(gpio, "rising");
+	gpio_fd = gpio_fd_open(gpio);
+
+	timeout = POLL_TIMEOUT;
+
+	while (1) {
+		memset((void*)fdset, 0, sizeof(fdset));
+
+		fdset[0].fd = STDIN_FILENO;
+		fdset[0].events = POLLIN;
+
+		fdset[1].fd = gpio_fd;
+		fdset[1].events = POLLPRI;
+
+		rc = poll(fdset, nfds, timeout);
+
+		if (rc < 0) {
+			printf("\npoll() failed!\n");
+			return -1;
+		}
+
+		if (rc == 0) {
+			printf(".");
+		}
+
+		if (fdset[1].revents & POLLPRI) {
+			lseek(fdset[1].fd, 0, SEEK_SET);
+			len = read(fdset[1].fd, buf, MAX_BUF);
+			printf("\npoll() GPIO %d interrupt occurred\n", gpio);
+			printf("\tread value: '%c'\n", buf[0]);
+		}
+
+		if (fdset[0].revents & POLLIN) {
+			(void)read(fdset[0].fd, buf, 1);
+			printf("\npoll() stdin read 0x%2.2X\n", (unsigned int) buf[0]);
+		}
+
+		fflush(stdout);
+	}
+
+	gpio_fd_close(gpio_fd);
+	return 0;
+}

makefile

@@ -0,0 +1,12 @@
+# main compiler
+CC := gcc
+
+TARGET1 := gpioIrq
+all: $(TARGET1) 
+
+$(TARGET1): 
+	@echo "Compiling C program"
+	$(CC) $(CFLAGS) $(TARGET1).c -o $(TARGET1)
+
+clean:
+	@rm -rf $(TARGET1)