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--- en:xu3_hardware_irq [2015/07/26 11:53]
charles.park
+++ en:xu3_hardware_irq [2016/01/30 11:36]
odroid [Usage]
@@ Line 1: / Line 1: @@
+====== Hardware GPIO-IRQ ======
+===== Usage =====
+To use the GPIO Interrupt in the User space, you must export the GPIO and add the Trigger option in Edge parameter.\\
+GPIO SYSFS node is accessible via **/sys/class/gpio/**.\\
+=== GPIO Export ===
+echo [GPIO Number(Refer **[[en:xu3_hardware_gpio]]** )] > /sys/class/gpio/export
+e.g) GPX2.0 Export (Header Pin Number 26)
+<code>
+echo 26 > /sys/class/gpio/export
+</code>
+=== User Space Example code ===
+This C example code shows the status of GPIO interrupts in the User Space.\\
+This example uses Both(rising + falling) edges on the GPIO.
+== Build ==
+<code>
+gcc -o gpio_irq_test gpio_irq_test.c
+</code>
+== Run ==
+<code>
+sudo gpio_irq_test [GPIO Number]
+</code>
+== Code ==
+<file c gpio_irq.c>
+//[*]-------------------------------------------------------------------------[*]
+//
+//  GPIO IRQ Test Application.
+//
+//[*]-------------------------------------------------------------------------[*]
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <poll.h>
+#include <sched.h>
+//[*]-------------------------------------------------------------------------[*]
+#define SYSFS_GPIO_DIR  "/sys/class/gpio"
+#define POLL_TIMEOUT    (3 * 1000) /* 3 seconds */
+#define MAX_BUF         64
+//[*]-------------------------------------------------------------------------[*]
+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;
+}
+//[*]-------------------------------------------------------------------------[*]
+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;
+}
+//[*]-------------------------------------------------------------------------[*]
+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;
+}
+//[*]-------------------------------------------------------------------------[*]
+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;
+}
+//[*]-------------------------------------------------------------------------[*]
+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;
+}
+//[*]-------------------------------------------------------------------------[*]
+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;
+}
+//[*]-------------------------------------------------------------------------[*]
+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;
+}
+//[*]-------------------------------------------------------------------------[*]
+int gpio_fd_close(int fd)
+{
+	return close(fd);
+}
+//[*]-------------------------------------------------------------------------[*]
+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;
+	if (argc < 2) {
+		printf("Usage: aml_gpio_irq <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, "both");    // High/Low Edge Trigger
+	gpio_fd = gpio_fd_open(gpio);
+	timeout = POLL_TIMEOUT;
+    // set a high priority schedulling for the running program
+    {
+        struct sched_param sched ;
+        memset (&sched, 0, sizeof(sched)) ;
+        sched.sched_priority = 55;
+        sched_setscheduler (0, SCHED_RR, &sched) ;
+    }
+	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("POLL Timeout!\n");
+		}
+		if (fdset[1].revents & POLLPRI) {
+			len = read(fdset[1].fd, buf, MAX_BUF);
+			printf("\npoll() GPIO %d interrupt occurred\n", gpio);
+		}
+		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;
+}
+//[*]-------------------------------------------------------------------------[*]
+//[*]-------------------------------------------------------------------------[*]
+</file>