fatfs: Add simple GPT support

This allows for a simple GPT parsing and checking first partition to see if it's FAT based.

This allows hekate booting GPT with tiny size cost.

bootloader/hos/hos.c

@@ -721,6 +721,10 @@ int hos_launch(ini_sec_t *cfg)
 		goto error;
 	}
 
+	// Check if SD Card is GPT.
+	if (sd_is_gpt())
+		_hos_crit_error("SD has GPT only!");
+
 	// Read package1 and the correct keyblob.
 	if (!_read_emmc_pkg1(&ctxt))
 		goto error;

bootloader/libs/fatfs/ffconf.h

@@ -46,11 +46,15 @@
 /* This option switches fast seek function. (0:Disable or 1:Enable) */
 
 #define FF_FASTFS 0
-
 #if FF_FASTFS
 #undef FF_USE_FASTSEEK
 #define FF_USE_FASTSEEK	1
 #endif
+/* This option switches fast access to chained clusters. (0:Disable or 1:Enable) */
+
+
+#define FF_SIMPLE_GPT 1
+/* This option switches support for the first GPT partition. (0:Disable or 1:Enable) */
 
 
 #define FF_USE_EXPAND	0
@@ -185,6 +189,7 @@
 /  not defined, a user defined volume string table needs to be defined as:
 /
 /  const char* VolumeStr[FF_VOLUMES] = {"ram","flash","sd","usb",...
+/  Order is important. Any change to order, must also be reflected to diskio drive enum.
 */
 
 
@@ -246,7 +251,7 @@
 #define FF_FS_NORTC		1
 #define FF_NORTC_MON	1
 #define FF_NORTC_MDAY	1
-#define FF_NORTC_YEAR	2020
+#define FF_NORTC_YEAR	2021
 /* The option FF_FS_NORTC switches timestamp function. If the system does not have
 /  any RTC function or valid timestamp is not needed, set FF_FS_NORTC = 1 to disable
 /  the timestamp function. Every object modified by FatFs will have a fixed timestamp

bootloader/storage/nx_sd.c

@@ -180,6 +180,11 @@ static void _sd_deinit()
 void sd_unmount() { _sd_deinit(); }
 void sd_end()     { _sd_deinit(); }
 
+bool sd_is_gpt()
+{
+	return sd_fs.part_type;
+}
+
 void *sd_file_read(const char *path, u32 *fsize)
 {
 	FIL fp;