S3C24XX large page NAND support

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

The basic stratergy is to maintain 3 bytes of ECC for each 256 byte block read from the NAND which is similar to the default kernel layout (altough we are using the hardware ECC generator to make our ECC calculations).

Signed-off-by Ben Dooks <[email protected]>

Index: linux-2.6.21-tmp/drivers/mtd/nand/s3c2410.c
===================================================================

drivers/mtd/nand/s3c2410.c +29 -4

@@ -473,7 +473,7 @@ static int s3c2440_nand_calculate_ecc(st
 	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;
 }

@@ -630,9 +630,6 @@ static void s3c2410_nand_init_chip(struc
 		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:

@@ -656,6 +653,34 @@ static void s3c2410_nand_init_chip(struc
 	}
 }
 
+/* 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

@@ -762,9 +787,12 @@ static int s3c24xx_nand_probe(struct pla
 
 		s3c2410_nand_init_chip(info, nmtd, sets);

Quoted 12 lines · Ben Dooks

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

The basic stratergy is to maintain 3 bytes of ECC for each 256 byte block read from the NAND which is similar to the default kernel layout (altough we are using the hardware ECC generator to make our ECC calculations).

Signed-off-by Ben Dooks <[email protected]>

drivers/mtd/nand/s3c2410.c static int s3c24xx_nand_probe(struct pla · line 797

Quoted 10 lines

drivers/mtd/nand/s3c2410.c +4 -1

-		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);
 		}

Shouldn't nand_scan_ident and nand_scan_tail be used here ?

On Thu, Jul 12, 2007 at 12:04:03PM +0200, Matthieu CASTET wrote:
[snip]

Quoted 11 lines

drivers/mtd/nand/s3c2410.c static int s3c24xx_nand_probe(struct pla · line 797

Quoted 10 lines

drivers/mtd/nand/s3c2410.c +4 -1

-		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);
 		}

Shouldn't nand_scan_ident and nand_scan_tail be used here ?

Sorry, do you mean that they should be used here (and they are being used in this code) or do you mean that you do not think that these two are to be used here?