MTD: S3C24XX large page NAND support

This adds support for using large page NAND devices
with the S3C24XX NAND controller. This also adds the 
file Documentation/arm/Samsung-S3C24XX/NAND.txt to
describe the differences.

Signed-off-by: Ben Dooks <ben-linux@fluff.org>

Index: linux-2.6.21.3-moko/drivers/mtd/nand/s3c2410.c
===================================================================
--- linux-2.6.21.3-moko.orig/drivers/mtd/nand/s3c2410.c
+++ linux-2.6.21.3-moko/drivers/mtd/nand/s3c2410.c
@@ -473,7 +473,7 @@
 	ecc_code[1] = ecc >> 8;
 	ecc_code[2] = ecc >> 16;
 
-	pr_debug("%s: returning ecc %06lx\n", __func__, ecc);
+	pr_debug("%s: returning ecc %06lx\n", __func__, ecc & 0xffffff);
 
 	return 0;
 }
@@ -648,9 +648,6 @@
 		chip->ecc.calculate = s3c2410_nand_calculate_ecc;
 		chip->ecc.correct   = s3c2410_nand_correct_data;
 		chip->ecc.mode	    = NAND_ECC_HW;
-		chip->ecc.size	    = 512;
-		chip->ecc.bytes	    = 3;
-		chip->ecc.layout    = &nand_hw_eccoob;
 
 		switch (info->cpu_type) {
 		case TYPE_S3C2410:
@@ -674,6 +671,34 @@
 	}
 }
 
+/* s3c2410_nand_update_chip
+ *
+ * post-probe chip update, to change any items, such as the
+ * layout for large page nand
+ */
+
+static void s3c2410_nand_update_chip(struct s3c2410_nand_info *info,
+				     struct s3c2410_nand_mtd *nmtd)
+{
+	struct nand_chip *chip = &nmtd->chip;
+
+	printk("%s: chip %p: %d\n", __func__, chip, chip->page_shift);
+
+	if (hardware_ecc) {
+		/* change the behaviour depending on wether we are using
+		 * the large or small page nand device */
+
+		if (chip->page_shift > 10) {
+			chip->ecc.size	    = 256;
+			chip->ecc.bytes	    = 3;
+		} else {
+			chip->ecc.size	    = 512;
+			chip->ecc.bytes	    = 3;
+			chip->ecc.layout    = &nand_hw_eccoob;
+		}
+	}
+}
+
 /* s3c2410_nand_probe
  *
  * called by device layer when it finds a device matching
@@ -780,9 +805,12 @@
 
 		s3c2410_nand_init_chip(info, nmtd, sets);
 
-		nmtd->scan_res = nand_scan(&nmtd->mtd, (sets) ? sets->nr_chips : 1);
+		nmtd->scan_res = nand_scan_ident(&nmtd->mtd,
+						 (sets) ? sets->nr_chips : 1);
 
 		if (nmtd->scan_res == 0) {
+			s3c2410_nand_update_chip(info, nmtd);
+			nand_scan_tail(&nmtd->mtd);
 			s3c2410_nand_add_partition(info, nmtd, sets);
 		}
 
Index: linux-2.6.21.3-moko/Documentation/arm/Samsung-S3C24XX/NAND.txt
===================================================================
--- /dev/null
+++ linux-2.6.21.3-moko/Documentation/arm/Samsung-S3C24XX/NAND.txt
@@ -0,0 +1,30 @@
+			S3C24XX NAND Support
+			====================
+
+Introduction
+------------
+
+Small Page NAND
+---------------
+
+The driver uses a 512 byte (1 page) ECC code for this setup. The
+ECC code is not directly compatible with the default kernel ECC
+code, so the driver enforces its own OOB layout and ECC parameters
+
+Large Page NAND
+---------------
+
+The driver is capable of handling NAND flash with a 2KiB page
+size, with support for hardware ECC generation and correction.
+
+Unlike the 512byte page mode, the driver generates ECC data for
+each 256 byte block in an 2KiB page. This means that more than
+one error in a page can be rectified. It also means that the
+OOB layout remains the default kernel layout for these flashes.
+
+
+Document Author
+---------------
+
+Ben Dooks, Copyright 2007 Simtec Electronics
+
Index: linux-2.6.21.3-moko/Documentation/arm/Samsung-S3C24XX/Overview.txt
===================================================================
--- linux-2.6.21.3-moko.orig/Documentation/arm/Samsung-S3C24XX/Overview.txt
+++ linux-2.6.21.3-moko/Documentation/arm/Samsung-S3C24XX/Overview.txt
@@ -156,6 +156,8 @@
   controller. If there are any problems the latest linux-mtd
   code can be found from http://www.linux-mtd.infradead.org/
 
+  For more information see Documentation/arm/Samsung-S3C24XX/NAND.txt
+
 
 Serial
 ------