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

[Lee Jones]

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 at linaro.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