linux-kernel - [RFC 18/47] mtd: nand: stm_nand_bch: ensure configuration is compatible with this driver

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Date:	Tue, 25 Mar 2014 08:19:35 +0000
From:	Lee Jones <lee.jones@...aro.org>
To:	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:	lee.jones@...aro.org, kernel@...inux.com,
	computersforpeace@...il.com, linux-mtd@...ts.infradead.org,
	dwmw2@...radead.org, angus.clark@...com, pekon@...com
Subject: [RFC 18/47] mtd: nand: stm_nand_bch: ensure configuration is compatible with this driver

Some chip characteristics have known incompatibilities with the function
of this driver. Here we check for this characteristics and refuse to run
if they are present.

Signed-off-by: Lee Jones <lee.jones@...aro.org>
---
 drivers/mtd/nand/stm_nand_bch.c | 39 ++++++++++++++++++++++++++++++++++++++-
 1 file changed, 38 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/nand/stm_nand_bch.c b/drivers/mtd/nand/stm_nand_bch.c
index 60a7800..365a73b 100644
--- a/drivers/mtd/nand/stm_nand_bch.c
+++ b/drivers/mtd/nand/stm_nand_bch.c
@@ -142,6 +142,36 @@ static void nandi_disable_interrupts(struct nandi_controller *nandi,
 	writel(val, nandi->base + NANDBCH_INT_EN);
 }
 
+/*
+ * Initialisation
+ */
+static int bch_check_compatibility(struct nandi_controller *nandi,
+				   struct mtd_info *mtd,
+				   struct nand_chip *chip)
+{
+	if (chip->bits_per_cell > 1)
+		dev_warn(nandi->dev, "MLC NAND not fully supported\n");
+
+	if (chip->options & NAND_BUSWIDTH_16) {
+		dev_err(nandi->dev, "x16 NAND not supported\n");
+		return false;
+	}
+
+	if (nandi->blocks_per_device / 4 > mtd->writesize) {
+		/* Need to implement multi-page BBT support... */
+		dev_err(nandi->dev, "BBT too big to fit in single page\n");
+		return false;
+	}
+
+	if (bch_ecc_sizes[nandi->bch_ecc_mode] * nandi->sectors_per_page >
+	    mtd->oobsize) {
+		dev_err(nandi->dev, "insufficient OOB for selected ECC\n");
+		return false;
+	}
+
+	return true;
+}
+
 /* Select strongest ECC scheme compatible with OOB size */
 static int bch_set_ecc_auto(struct nandi_controller *nandi,
 			    struct mtd_info *mtd)
@@ -737,7 +767,7 @@ static int stm_nand_bch_probe(struct platform_device *pdev)
 	struct nandi_info *info;
 	struct nand_chip *chip;
 	struct mtd_info *mtd;
-	int err;
+	int compatible, err;
 
 	if (!pdata) {
 		if (!np) {
@@ -832,6 +862,13 @@ static int stm_nand_bch_probe(struct platform_device *pdev)
 	info->ecclayout.eccbytes =
 		nandi->sectors_per_page * bch_ecc_sizes[nandi->bch_ecc_mode];
 
+	compatible = bch_check_compatibility(nandi, mtd, chip);
+	if (!compatible) {
+		dev_err(nandi->dev,
+			"NAND device incompatible with NANDi/BCH Controller\n");
+		return -EINVAL;
+	}
+
 	return 0;
 }
 
-- 
1.8.3.2

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