u-boot/doc/README.JFFS2_NAND

JFFS2 NAND support:

To enable, use the following #define in the board configuration file:

#define CONFIG_JFFS2_NAND 1

Configuration of partitions is similar to how this is done in  U-Boot
for  JFFS2  on top NOR flash. If a single partition is used, it can be
configured using the following #defines in the configuration file:

#define CONFIG_JFFS2_NAND_DEV 0			/* nand device jffs2 lives on */
#define CONFIG_JFFS2_NAND_OFF 0			/* start of jffs2 partition */
#define CONFIG_JFFS2_NAND_SIZE 2*1024*1024	/* size of jffs2 partition */

If more than a single partition is desired, the user can define a
CONFIG_SYS_JFFS_CUSTOM_PART macro and implement a

	struct part_info* jffs2_part_info(int part_num)

function in a board-specific module. An example of such function is
available in common/cmd_jffs2.c

The default configuration for the DAVE board has a single JFFS2
partition of 2 MB size.