FAT: Add FAT write feature

In some cases, saving data in RAM as a file with FAT format is required.
This patch allows the file to be written in FAT formatted partition.

The usage is similar with reading a file.
First, fat_register_device function is called before file_fat_write function
in order to set target partition.
Then, file_fat_write function is invoked with desired file name,
start ram address for writing data, and file size.

Signed-off-by: Donggeun Kim <dg77.kim@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>

README

@@ -1175,6 +1175,11 @@ The following options need to be configured:
 		to disable the command chpart. This is the default when you
 		have not defined a custom partition
 
+- FAT(File Allocation Table) filesystem write function support:
+		CONFIG_FAT_WRITE
+		Support for saving memory data as a file
+		in FAT formatted partition
+
 - Keyboard Support:
 		CONFIG_ISA_KEYBOARD
 

fs/fat/Makefile

@@ -25,6 +25,7 @@ LIB	= $(obj)libfat.o
 
 AOBJS	=
 COBJS-$(CONFIG_CMD_FAT)	:= fat.o
+COBJS-$(CONFIG_FAT_WRITE):= fat_write.o
 
 ifndef CONFIG_SPL_BUILD
 COBJS-$(CONFIG_CMD_FAT)	+= file.o

fs/fat/fat.c

@@ -46,6 +46,7 @@ static void downcase (char *str)
 static block_dev_desc_t *cur_dev = NULL;
 
 static unsigned long part_offset = 0;
+static unsigned long part_size;
 
 static int cur_part = 1;
 
@@ -99,6 +100,7 @@ int fat_register_device (block_dev_desc_t * dev_desc, int part_no)
 	if (!get_partition_info(dev_desc, part_no, &info)) {
 		part_offset = info.start;
 		cur_part = part_no;
+		part_size = info.size;
 	} else if ((strncmp((char *)&buffer[DOS_FS_TYPE_OFFSET], "FAT", 3) == 0) ||
 		   (strncmp((char *)&buffer[DOS_FS32_TYPE_OFFSET], "FAT32", 5) == 0)) {
 		/* ok, we assume we are on a PBR only */

include/fat.h

@@ -99,6 +99,8 @@
 #endif
 
 #define TOLOWER(c)	if((c) >= 'A' && (c) <= 'Z'){(c)+=('a' - 'A');}
+#define TOUPPER(c)	if ((c) >= 'a' && (c) <= 'z') \
+				(c) -= ('a' - 'A');
 #define START(dent)	(FAT2CPU16((dent)->start) \
 			+ (mydata->fatsize != 32 ? 0 : \
 			  (FAT2CPU16((dent)->starthi) << 16)))
@@ -210,4 +212,5 @@ long file_fat_read(const char *filename, void *buffer, unsigned long maxsize);
 const char *file_getfsname(int idx);
 int fat_register_device(block_dev_desc_t *dev_desc, int part_no);
 
+int file_fat_write(const char *filename, void *buffer, unsigned long maxsize);
 #endif /* _FAT_H_ */