linux-kernel - [RFC] mtd: fsl_elbc_nand Add ECC mode selection in DT

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Message-Id: <1429690690-15057-1-git-send-email-tmshlvck@gmail.com>
Date:	Wed, 22 Apr 2015 10:18:10 +0200
From:	Tomas Hlavacek <tmshlvck@...il.com>
To:	dwmw2@...radead.org
Cc:	computersforpeace@...il.com, scottwood@...escale.com,
	linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [RFC] mtd: fsl_elbc_nand Add ECC mode selection in DT

Add device tree parameters to turn off the HW ECC and force own ECC mode
and ECC parameters. New entries are: nand-ecc-mode, nand-ecc-step-size
and nand-ecc-strength.

Add RNDOUT operation which is required for SOFT and SOFT_BCH modes.

Do not set write_subpage function pointer from the driver when it initializes
in SOFT and SOFT_BCH modes.

Signed-off-by: Tomas Hlavacek <tmshlvck@...il.com>
---
 drivers/mtd/nand/fsl_elbc_nand.c | 47 +++++++++++++++++++++++++++++++++++++---
 1 file changed, 44 insertions(+), 3 deletions(-)

diff --git a/drivers/mtd/nand/fsl_elbc_nand.c b/drivers/mtd/nand/fsl_elbc_nand.c
index 04b22fd..76ab2e2 100644
--- a/drivers/mtd/nand/fsl_elbc_nand.c
+++ b/drivers/mtd/nand/fsl_elbc_nand.c
@@ -335,6 +335,14 @@ static void fsl_elbc_cmdfunc(struct mtd_info *mtd, unsigned int command,
 		fsl_elbc_run_command(mtd);
 		return;
 
+	case NAND_CMD_RNDOUT:
+		dev_vdbg(priv->dev,
+			 "fsl_elbc_cmdfunc: NAND_CMD_RNDOUT, column: 0x%x.\n",
+			 column);
+
+		elbc_fcm_ctrl->index = column;
+		return;
+
 	/* READOOB reads only the OOB because no ECC is performed. */
 	case NAND_CMD_READOOB:
 		dev_vdbg(priv->dev,
@@ -656,6 +664,10 @@ static int fsl_elbc_chip_init_tail(struct mtd_info *mtd)
 	        chip->ecc.steps);
 	dev_dbg(priv->dev, "fsl_elbc_init: nand->ecc.bytes = %d\n",
 	        chip->ecc.bytes);
+	dev_dbg(priv->dev, "fsl_elbc_init: nand->ecc.size = %d\n",
+		chip->ecc.size);
+	dev_dbg(priv->dev, "fsl_elbc_init: nand->ecc.strength = %d\n",
+		chip->ecc.strength);
 	dev_dbg(priv->dev, "fsl_elbc_init: nand->ecc.total = %d\n",
 	        chip->ecc.total);
 	dev_dbg(priv->dev, "fsl_elbc_init: nand->ecc.layout = %p\n",
@@ -677,8 +689,8 @@ static int fsl_elbc_chip_init_tail(struct mtd_info *mtd)
 		priv->page_size = 1;
 		setbits32(&lbc->bank[priv->bank].or, OR_FCM_PGS);
 		/* adjust ecc setup if needed */
-		if ((in_be32(&lbc->bank[priv->bank].br) & BR_DECC) ==
-		    BR_DECC_CHK_GEN) {
+		if (((in_be32(&lbc->bank[priv->bank].br) & BR_DECC) ==
+		    BR_DECC_CHK_GEN) && (chip->ecc.mode == NAND_ECC_HW)) {
 			chip->ecc.size = 512;
 			chip->ecc.layout = (priv->fmr & FMR_ECCM) ?
 			                   &fsl_elbc_oob_lp_eccm1 :
@@ -742,6 +754,8 @@ static int fsl_elbc_chip_init(struct fsl_elbc_mtd *priv)
 	struct fsl_lbc_regs __iomem *lbc = ctrl->regs;
 	struct fsl_elbc_fcm_ctrl *elbc_fcm_ctrl = ctrl->nand;
 	struct nand_chip *chip = &priv->chip;
+	struct device_node *node = priv->dev->of_node;
+	const char *ecc_mode;
 
 	dev_dbg(priv->dev, "eLBC Set Information for bank %d\n", priv->bank);
 
@@ -774,11 +788,38 @@ static int fsl_elbc_chip_init(struct fsl_elbc_mtd *priv)
 
 	chip->ecc.read_page = fsl_elbc_read_page;
 	chip->ecc.write_page = fsl_elbc_write_page;
-	chip->ecc.write_subpage = fsl_elbc_write_subpage;
+
+	/* Override default HW ECC according to settings in DT */
+	if (!of_property_read_string(node, "nand-ecc-mode", &ecc_mode)) {
+		if (!strncmp("none", ecc_mode, 4)) {
+			chip->ecc.mode = NAND_ECC_NONE;
+			return 0;
+		}
+
+		if (!strncmp("soft_bch", ecc_mode, 8)) {
+			chip->ecc.mode = NAND_ECC_SOFT_BCH;
+			chip->ecc.size = 512;
+			chip->ecc.strength = 4;
+
+			of_property_read_u32(node, "nand-ecc-step-size",
+						&chip->ecc.size);
+			of_property_read_u32(node, "nand-ecc-strength",
+						&chip->ecc.strength);
+			chip->ecc.bytes = ((fls(1+8*chip->ecc.size)*
+				chip->ecc.strength)/8);
+			return 0;
+		}
+
+		if (!strncmp("soft", ecc_mode, 4)) {
+			chip->ecc.mode = NAND_ECC_SOFT;
+			return 0;
+		}
+	}
 
 	/* If CS Base Register selects full hardware ECC then use it */
 	if ((in_be32(&lbc->bank[priv->bank].br) & BR_DECC) ==
 	    BR_DECC_CHK_GEN) {
+		chip->ecc.write_subpage = fsl_elbc_write_subpage;
 		chip->ecc.mode = NAND_ECC_HW;
 		/* put in small page settings and adjust later if needed */
 		chip->ecc.layout = (priv->fmr & FMR_ECCM) ?
-- 
2.1.4

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