[JFFS2] Add support for JFFS2-on-Dataflash devices.

For Dataflash, can_mark_obsolete = false and the NAND write buffering
code (wbuf.c) is used.

Since the DataFlash chip will automatically erase pages when writing,
the cleanmarkers are not needed - so cleanmarker_oob = false and
cleanmarker_size = 0

DataFlash page-sizes are not a power of two (they're multiples of 528
bytes).  The SECTOR_ADDR macro (added in the previous core patch) is
replaced with a (slower) div/mod version if CONFIG_JFFS2_FS_DATAFLASH is
selected.

Signed-off-by: Andrew Victor <andrew@sanpeople.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

include/linux/jffs2_fs_sb.h

@@ -1,4 +1,4 @@
-/* $Id: jffs2_fs_sb.h,v 1.48 2004/11/20 10:41:12 dwmw2 Exp $ */
+/* $Id: jffs2_fs_sb.h,v 1.49 2005/02/09 09:17:41 pavlov Exp $ */
 
 #ifndef _JFFS2_FS_SB
 #define _JFFS2_FS_SB
@@ -94,7 +94,7 @@ struct jffs2_sb_info {
 	   to an obsoleted node. I don't like this. Alternatives welcomed. */
 	struct semaphore erase_free_sem;
 
-#if defined CONFIG_JFFS2_FS_NAND || defined CONFIG_JFFS2_FS_NOR_ECC
+#if defined CONFIG_JFFS2_FS_NAND || defined CONFIG_JFFS2_FS_NOR_ECC || defined CONFIG_JFFS2_FS_DATAFLASH
 	/* Write-behind buffer for NAND flash */
 	unsigned char *wbuf;
 	uint32_t wbuf_ofs;

include/mtd/mtd-abi.h

@@ -1,5 +1,5 @@
 /*
- * $Id: mtd-abi.h,v 1.9 2005/02/08 17:45:52 nico Exp $
+ * $Id: mtd-abi.h,v 1.10 2005/02/09 09:17:42 pavlov Exp $
  *
  * Portions of MTD ABI definition which are shared by kernel and user space 
  */
@@ -29,6 +29,7 @@ struct mtd_oob_buf {
 #define MTD_NORFLASH		3
 #define MTD_NANDFLASH		4
 #define MTD_PEROM		5
+#define MTD_DATAFLASH		6
 #define MTD_OTHER		14
 #define MTD_UNKNOWN		15