mxc_nand: support 8bit ecc

[Linux-MTD Mailing List]

Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=6e85dfdc19ef526edec285aed47c83934882e9bd
Commit:     6e85dfdc19ef526edec285aed47c83934882e9bd
Parent:     94f77e50d658be1d3ff23fb65e4d075a6f4ebee3
Author:     Sascha Hauer <s.hauer at pengutronix.de>
AuthorDate: Fri Aug 6 15:53:10 2010 +0200
Committer:  David Woodhouse <David.Woodhouse at intel.com>
CommitDate: Fri Aug 6 16:38:03 2010 +0100

    mxc_nand: support 8bit ecc
    
    Nand devices with at least 26 bytes of oob data per 512 byte block
    can have 8bit ecc on v2 type controllers. This is currently not tested,
    but at least this patch puts the ECC_MODE bit into a well defined state.
    
    Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
    Signed-off-by: David Woodhouse <David.Woodhouse at intel.com>
---
 drivers/mtd/nand/mxc_nand.c |   30 ++++++++++++++++++++++++++++++
 1 files changed, 30 insertions(+), 0 deletions(-)

diff --git a/drivers/mtd/nand/mxc_nand.c b/drivers/mtd/nand/mxc_nand.c
index f5fd254..1433a83 100644
--- a/drivers/mtd/nand/mxc_nand.c
+++ b/drivers/mtd/nand/mxc_nand.c
@@ -58,6 +58,7 @@
 #define NFC_V1_V2_CONFIG1		(host->regs + 0x1a)
 #define NFC_V1_V2_CONFIG2		(host->regs + 0x1c)
 
+#define NFC_V2_CONFIG1_ECC_MODE_4	(1 << 0)
 #define NFC_V1_V2_CONFIG1_SP_EN		(1 << 2)
 #define NFC_V1_V2_CONFIG1_ECC_EN	(1 << 3)
 #define NFC_V1_V2_CONFIG1_INT_MSK	(1 << 4)
@@ -581,6 +582,23 @@ static void mxc_do_addr_cycle(struct mtd_info *mtd, int column, int page_addr)
 	}
 }
 
+/*
+ * v2 and v3 type controllers can do 4bit or 8bit ecc depending
+ * on how much oob the nand chip has. For 8bit ecc we need at least
+ * 26 bytes of oob data per 512 byte block.
+ */
+static int get_eccsize(struct mtd_info *mtd)
+{
+	int oobbytes_per_512 = 0;
+
+	oobbytes_per_512 = mtd->oobsize * 512 / mtd->writesize;
+
+	if (oobbytes_per_512 < 26)
+		return 4;
+	else
+		return 8;
+}
+
 static void preset_v1_v2(struct mtd_info *mtd)
 {
 	struct nand_chip *nand_chip = mtd->priv;
@@ -596,6 +614,15 @@ static void preset_v1_v2(struct mtd_info *mtd)
 	} else {
 		tmp &= ~NFC_V1_V2_CONFIG1_ECC_EN;
 	}
+
+	if (nfc_is_v21() && mtd->writesize) {
+		host->eccsize = get_eccsize(mtd);
+		if (host->eccsize == 4)
+			tmp |= NFC_V2_CONFIG1_ECC_MODE_4;
+	} else {
+		host->eccsize = 1;
+	}
+
 	writew(tmp, NFC_V1_V2_CONFIG1);
 	/* preset operation */
 
@@ -859,6 +886,9 @@ static int __init mxcnd_probe(struct platform_device *pdev)
 		goto escan;
 	}
 
+	/* Call preset again, with correct writesize this time */
+	host->preset(mtd);
+
 	if (mtd->writesize == 2048)
 		this->ecc.layout = oob_largepage;