tests: fs: fat_fs_api: add timestamp integration

Add an example implementation of `get_fattime` to the API tests. Also
ensure that `FS_FATFS_EXTRA_NATIVE_API` compiles in a test.

Signed-off-by: Jordan Yates <[email protected]>

Author: JordanYates

tests/subsys/fs/fat_fs_api/prj.conf

@@ -6,3 +6,6 @@ CONFIG_DISK_DRIVER_FLASH=y
 CONFIG_ZTEST=y
 CONFIG_FLASH=y
 CONFIG_FLASH_MAP=y
+
+# Demonstrate filesystem time integration
+CONFIG_FS_FATFS_HAS_RTC=y

tests/subsys/fs/fat_fs_api/prj_lfn.conf

@@ -3,6 +3,7 @@ CONFIG_FILE_SYSTEM_MKFS=y
 CONFIG_LOG=y
 CONFIG_FAT_FILESYSTEM_ELM=y
 CONFIG_FS_FATFS_LFN=y
+CONFIG_FS_FATFS_EXTRA_NATIVE_API=y
 CONFIG_DISK_DRIVER_FLASH=y
 CONFIG_ZTEST=y
 CONFIG_FLASH=y

tests/subsys/fs/fat_fs_api/src/main.c

@@ -5,11 +5,27 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
+#include <time.h>
 
 #include "test_fat.h"
 void test_fs_open_flags(void);
 const char *test_fs_open_flags_file_path =  FATFS_MNTP"/the_file.txt";
 
+/* Time integration for filesystem */
+DWORD get_fattime(void)
+{
+	time_t unix_time = time(NULL);
+	struct tm *cal;
+
+	/* Convert to calendar time */
+	cal = localtime(&unix_time);
+
+	/* From http://elm-chan.org/fsw/ff/doc/fattime.html */
+	return (DWORD)(cal->tm_year - 80) << 25 | (DWORD)(cal->tm_mon + 1) << 21 |
+	       (DWORD)cal->tm_mday << 16 | (DWORD)cal->tm_hour << 11 | (DWORD)cal->tm_min << 5 |
+	       (DWORD)cal->tm_sec >> 1;
+}
+
 static void *fat_fs_basic_setup(void)
 {
 	fs_file_t_init(&filep);