create library

src/gpio.c

@@ -9,11 +9,7 @@
 #include <sys/stat.h>
 #include <sys/types.h>
 
-#define IN	0
-#define OUT	1
-
-#define LOW	0
-#define HIGH	1
+#include <gpio_sys.h>
 
 #define PIN	24
 #define POUT	4
@@ -22,6 +18,97 @@
 #define DIRECTION_MAX	35
 #define VALUE_MAX	30
 
+static int gpio_export(int pin);
+static int gpio_unexport(int pin);
+static int gpio_direction(int pin, int dir);
+
+int gpio_open(const struct gpio_sys *gpio)
+{
+    int res;
+
+    assert(NULL != gpio);
+
+    syslog(LOG_DEBUG, "Start opening gpio pin %d.\n", gpio->pin);
+    res = gpio_export(gpio->pin);
+    if(res < 0) {
+        syslog(LOG_ERR, "Unable to export pin %d.\n", gpio->pin);
+        return res;
+    }
+
+    res = gpio_direction(gpio->pin, gpio->direction);
+    if(res < 0) {
+        syslog(LOG_ERR, "Unable to set direction for pin %d.\n", gpio->pin);
+        return res;
+    }
+
+    syslog(LOG_DEBUG, "Gpio pin %d successfully opened.\n", gpio->pin);
+    return 0;
+}
+
+int gpio_close(const struct gpio_sys *gpio)
+{
+    int res;
+
+    assert(NULL != gpio);
+
+    syslog(LOG_DEBUG, "Start closing gpio pin %d\n.", gpio->pin);
+    res = gpio_unexport(gpio->pin);
+    if(res < 0) {
+        syslog(LOG_ERR, "Unable to unexport pin %d.\n", gpio->pin);
+        return res;
+    }
+
+    syslog(LOG_DEBUG, "Gpio pin %d successfully closed.\n", gpio->pin);
+    return 0;
+}
+
+int gpio_read(const struct gpio_sys *gpio)
+{
+    char path[VALUE_MAX];
+    char value_str[BUF_SIZE];
+    int fd;
+
+    assert(NULL != gpio);
+    snprintf(path, VALUE_MAX, "/sys/class/gpio/gpio%d/value", gpio->pin);
+    fd = open(path, O_RDONLY);
+    if(-1 == fd) {
+        syslog(LOG_ERR, "Failed to open pin %d value for reading.\n", gpio->pin);
+        return -1;
+    }
+
+    if(-1 == read(fd, value_str, BUF_SIZE)) {
+        syslog(LOG_ERR, "Failed to read value for pin %d.\n", gpio->pin);
+        return -1;
+    }
+    close(fd);
+
+    return(atoi(value_str));
+}
+
+int gpio_write(const struct gpio_sys *gpio, int value)
+{
+    static const char s_values_str[] = "01";
+    char path[VALUE_MAX];
+    int fd;
+
+    assert(NULL != gpio);
+
+    snprintf(path, VALUE_MAX, "/sys/class/gpio/gpio%d/value", gpio->pin);
+    fd = open(path, O_WRONLY);
+    if(-1 == fd) {
+        syslog(LOG_ERR, "Failed to open pin %d value for writing.\n", gpio->pin);
+        return -1;
+    }
+
+    if(1 != write(fd, &s_values_str[LOW == value ? 0 : 1], 1)) {
+        syslog(LOG_ERR, "Failed to write value for pin %d.\n", gpio->pin);
+        return -1;
+    }
+    close(fd);
+
+    return 0;
+}
+
 static int gpio_export(int pin)
 {
     char buffer[BUF_SIZE];
@@ -30,7 +117,7 @@ static int gpio_export(int pin)
 
     fd = open("/sys/class/gpio/export", O_WRONLY);
     if(-1 == fd) {
-        fprintf(stderr, "Failed to open export for writing!\n");
+        syslog(LOG_ERR, "Failed to open export for writing.\n");
         return -1;
     }
 
@@ -49,7 +136,7 @@ static int gpio_unexport(int pin)
 
     fd = open("/sys/class/gpio/unexport", O_WRONLY);
     if(-1 == fd) {
-        fprintf(stderr, "Failed to open unexport for writing!\n");
+        syslog(LOG_ERR, "Failed to open unexport for writing.\n");
         return -1;
     }
 
@@ -69,88 +156,15 @@ static int gpio_direction(int pin, int dir)
     snprintf(path, DIRECTION_MAX, "/sys/class/gpio/gpio%d/direction", pin);
     fd = open(path, O_WRONLY);
     if(-1 == fd) {
-        fprintf(stderr, "Failed to open gpio direction for writing!\n");
+        syslog(LOG_ERR, "Failed to open direction for writing.\n");
         return -1;
     }
 
     if(-1 == write(fd, &directions_str[IN == dir ? 0 : 3], IN == dir ? 2 : 3)) {
-        fprintf(stderr, "Failed to set direction!\n");
+        syslog(LOG_ERR, "Failed to set direction.\n");
         return -1;
     }
     close(fd);
 
     return 0;
 }
-
-static int gpio_read(int pin)
-{
-    char path[VALUE_MAX];
-    char value_str[BUF_SIZE];
-    int fd;
-
-    snprintf(path, VALUE_MAX, "/sys/class/gpio/gpio%d/value", pin);
-    fd = open(path, O_RDONLY);
-    if(-1 == fd) {
-        fprintf(stderr, "Failed to open gpio value for reading!\n");
-        return -1;
-    }
-
-    if(-1 == read(fd, value_str, BUF_SIZE)) {
-        fprintf(stderr, "Failed to read value!\n");
-        return -1;
-    }
-    close(fd);
-
-    return(atoi(value_str));
-}
-
-static int gpio_write(int pin, int value)
-{
-    static const char s_values_str[] = "01";
-    char path[VALUE_MAX];
-    int fd;
-
-    snprintf(path, VALUE_MAX, "/sys/class/gpio/gpio%d/value", pin);
-    fd = open(path, O_WRONLY);
-    if(-1 == fd) {
-        fprintf(stderr, "Failed to open gpio value for writing!\n");
-        return -1;
-    }
-
-    if(1 != write(fd, &s_values_str[LOW == value ? 0 : 1], 1)) {
-        fprintf(stderr, "Failed to write value!\n");
-        return -1;
-    }
-    close(fd);
-
-    return 0;
-}
-
-int main(void)
-{
-    int repeat = 10;
-
-    if(-1 == gpio_export(POUT) || -1 == gpio_export(PIN)) {
-        return(1);
-    }
-
-    if(-1 == gpio_direction(POUT, OUT) || -1 == gpio_direction(PIN, IN)) {
-        return(2);
-    }
-
-    do {
-        if(-1 == gpio_write(POUT, repeat % 2)) {
-            return(3);
-        }
-
-	printf("I'm reading %d in GPIO %d\n", gpio_read(PIN), PIN);
-        usleep(500 * 1000);
-    } while(repeat--);
-
-    if(-1 == gpio_unexport(POUT) || -1 == gpio_unexport(PIN)) {
-	return(4);
-    }
-
-    return(0);
-}
-