mtd: rawnand: Add a NAND_NO_BBM_QUIRK flag

Some controllers with embedded ECC engines override the BBM marker with
data or ECC bytes, thus making bad block detection through bad block
marker impossible. Let's flag those chips so the core knows it shouldn't
check the BBM and consider all blocks good.

This should allow us to get rid of two implementers of the
legacy.block_bad() hook.
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20200511064917.6255-1-boris.brezillon@collabora.com

drivers/mtd/nand/raw/nand_base.c

@@ -395,6 +395,9 @@ static int nand_block_bad(struct nand_chip *chip, loff_t ofs)
 
 static int nand_isbad_bbm(struct nand_chip *chip, loff_t ofs)
 {
+	if (chip->options & NAND_NO_BBM_QUIRK)
+		return 0;
+
 	if (chip->legacy.block_bad)
 		return chip->legacy.block_bad(chip, ofs);
 

include/linux/mtd/rawnand.h

@@ -221,6 +221,14 @@ enum nand_ecc_algo {
 #define NAND_BBM_SECONDPAGE	BIT(25)
 #define NAND_BBM_LASTPAGE	BIT(26)
 
+/*
+ * Some controllers with pipelined ECC engines override the BBM marker with
+ * data or ECC bytes, thus making bad block detection through bad block marker
+ * impossible. Let's flag those chips so the core knows it shouldn't check the
+ * BBM and consider all blocks good.
+ */
+#define NAND_NO_BBM_QUIRK	BIT(27)
+
 /* Cell info constants */
 #define NAND_CI_CHIPNR_MSK	0x03
 #define NAND_CI_CELLTYPE_MSK	0x0C