esp32/fatfs_port: Implement get_fattime so FAT files have a timestamp.

Fixes issue #3859.

ports/esp32/fatfs_port.c

@@ -26,20 +26,15 @@
  * THE SOFTWARE.
  */
 
-#include "py/obj.h"
+#include <sys/time.h>
 #include "lib/oofatfs/ff.h"
 #include "timeutils.h"
-//#include "modmachine.h"
 
 DWORD get_fattime(void) {
-
-    // TODO: Optimize division (there's no HW division support on ESP8266,
-    // so it's expensive).
-    //uint32_t secs = (uint32_t)(pyb_rtc_get_us_since_2000() / 1000000);
-    uint32_t secs = 0;
-
+    struct timeval tv;
+    gettimeofday(&tv, NULL);
     timeutils_struct_time_t tm;
-    timeutils_seconds_since_2000_to_struct_time(secs, &tm);
+    timeutils_seconds_since_2000_to_struct_time(tv.tv_sec, &tm);
 
     return (((DWORD)(tm.tm_year - 1980) << 25) | ((DWORD)tm.tm_mon << 21) | ((DWORD)tm.tm_mday << 16) |
            ((DWORD)tm.tm_hour << 11) | ((DWORD)tm.tm_min << 5) | ((DWORD)tm.tm_sec >> 1));