Include first driver: SHT31

Make I2C reads blocking w/ timeout
Add SHT31 driver, roughly :)
Fix mg_time() to return a double.

include/mgos_i2c.h

@@ -12,6 +12,15 @@
 #pragma once
 
 #include "mgos.h"
+#include <stdio.h>
+#include <linux/i2c.h>
+#include <linux/i2c-dev.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/ioctl.h>
+#include <string.h>
+
 
 /* Each platform defines its own I2C connection parameters. */
 struct mgos_i2c;
@@ -113,5 +122,6 @@ void mgos_i2c_close(struct mgos_i2c *conn);
 struct mgos_i2c *mgos_i2c_get_global(void);
 
 // User contributed!
+int get_i2c_register(struct mgos_i2c *i2c, uint8_t addr, uint8_t reg, uint8_t *val);
 bool mgos_i2c_open(int busnr);
 

include/mgos_mock.h

@@ -30,6 +30,8 @@ int log_print_prefix(enum cs_log_level l, const char *func, const char *file);
   } while (0)
 
 
-float mg_time();
+double mg_time();
+
+void mgos_usleep(uint32_t usecs);
 
 #endif // __MGOS_MOCK_H

include/mgos_sht31.h

@@ -0,0 +1,57 @@
+#pragma once
+
+#include "mgos.h"
+#include "mgos_i2c.h"
+
+#define MGOS_SHT31_READ_DELAY (2)
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct mgos_sht31;
+
+/*
+ *
+ */
+struct mgos_sht31 *mgos_sht31_create(struct mgos_i2c *i2c, uint8_t i2caddr);
+
+/*
+ *
+ */
+void mgos_sht31_destroy(struct mgos_sht31 **sensor);
+
+/*
+ *
+ */
+bool mgos_sht31_read(struct mgos_sht31 *sensor);
+
+/*
+ *
+ */
+void mgos_sht31_setHeater(struct mgos_sht31 *sensor, bool enabled);
+
+/*
+ *
+ */
+float mgos_sht31_getTemperature(struct mgos_sht31 *sensor);
+
+/*
+ *
+ */
+float mgos_sht31_getHumidity(struct mgos_sht31 *sensor);
+
+
+/*
+ *
+ */
+uint16_t mgos_sht31_getStatus(struct mgos_sht31 *sensor);
+
+/*
+ *
+ */
+bool mgos_sht31_i2c_init(void);
+
+#ifdef __cplusplus
+}
+#endif