Add nrf52 gpio driver abstraction

include/gpio.h

@@ -0,0 +1,34 @@
+#ifndef __GPIO_H__
+#define __GPIO_H__
+
+#include <stdarg.h>
+
+#include "driver.h"
+
+#define IOCTL_CMD_SET_DIRECTION 0
+
+int gpio_open(const struct driver *drv);
+int gpio_close(const struct driver *drv);
+
+int gpio_read(const struct driver *drv, char *buffer, unsigned int len);
+int gpio_write(const struct driver *drv, const char *buffer, unsigned int len);
+
+enum direction {
+    IN = 0,
+    OUT
+};
+
+struct gpio {
+    int pin;
+    enum direction dir;
+};
+
+static const struct driver_fp gpio_fp = {
+    .open = gpio_open,
+    .close = gpio_close,
+    .read = gpio_read,
+    .write = gpio_write,
+    .ioctl = NULL
+};
+
+#endif