mtd: nand: Sync with Linux v4.6

Updates the NAND code to match Linux v4.6.  The previous sync was from
Linux v4.1 in commit d3963721d93fafa.

Note that none of the individual NAND drivers tracked Linux closely
enough to be synced themselves, other than manually applying a few
cross-tree changes.

Signed-off-by: Scott Wood <oss@buserror.net>
Tested-by: Heiko Schocher <hs@denx.de>
diff --git a/drivers/mtd/nand/nand_bch.c b/drivers/mtd/nand/nand_bch.c
index d7f6ce0..c145203 100644
--- a/drivers/mtd/nand/nand_bch.c
+++ b/drivers/mtd/nand/nand_bch.c
@@ -86,7 +86,7 @@
 		}
 	} else if (count < 0) {
 		printk(KERN_ERR "ecc unrecoverable error\n");
-		count = -1;
+		count = -EBADMSG;
 	}
 	return count;
 }
@@ -94,9 +94,6 @@
 /**
  * nand_bch_init - [NAND Interface] Initialize NAND BCH error correction
  * @mtd:	MTD block structure
- * @eccsize:	ecc block size in bytes
- * @eccbytes:	ecc length in bytes
- * @ecclayout:	output default layout
  *
  * Returns:
  *  a pointer to a new NAND BCH control structure, or NULL upon failure
@@ -110,14 +107,21 @@
  * @eccsize = 512  (thus, m=13 is the smallest integer such that 2^m-1 > 512*8)
  * @eccbytes = 7   (7 bytes are required to store m*t = 13*4 = 52 bits)
  */
-struct nand_bch_control *
-nand_bch_init(struct mtd_info *mtd, unsigned int eccsize, unsigned int eccbytes,
-	      struct nand_ecclayout **ecclayout)
+struct nand_bch_control *nand_bch_init(struct mtd_info *mtd)
 {
+	struct nand_chip *nand = mtd_to_nand(mtd);
 	unsigned int m, t, eccsteps, i;
-	struct nand_ecclayout *layout;
+	struct nand_ecclayout *layout = nand->ecc.layout;
 	struct nand_bch_control *nbc = NULL;
 	unsigned char *erased_page;
+	unsigned int eccsize = nand->ecc.size;
+	unsigned int eccbytes = nand->ecc.bytes;
+	unsigned int eccstrength = nand->ecc.strength;
+
+	if (!eccbytes && eccstrength) {
+		eccbytes = DIV_ROUND_UP(eccstrength * fls(8 * eccsize), 8);
+		nand->ecc.bytes = eccbytes;
+	}
 
 	if (!eccsize || !eccbytes) {
 		printk(KERN_WARNING "ecc parameters not supplied\n");
@@ -145,7 +149,7 @@
 	eccsteps = mtd->writesize/eccsize;
 
 	/* if no ecc placement scheme was provided, build one */
-	if (!*ecclayout) {
+	if (!layout) {
 
 		/* handle large page devices only */
 		if (mtd->oobsize < 64) {
@@ -171,7 +175,7 @@
 		layout->oobfree[0].offset = 2;
 		layout->oobfree[0].length = mtd->oobsize-2-layout->eccbytes;
 
-		*ecclayout = layout;
+		nand->ecc.layout = layout;
 	}
 
 	/* sanity checks */
@@ -179,7 +183,7 @@
 		printk(KERN_WARNING "eccsize %u is too large\n", eccsize);
 		goto fail;
 	}
-	if ((*ecclayout)->eccbytes != (eccsteps*eccbytes)) {
+	if (layout->eccbytes != (eccsteps*eccbytes)) {
 		printk(KERN_WARNING "invalid ecc layout\n");
 		goto fail;
 	}
@@ -203,6 +207,9 @@
 	for (i = 0; i < eccbytes; i++)
 		nbc->eccmask[i] ^= 0xff;
 
+	if (!eccstrength)
+		nand->ecc.strength = (eccbytes * 8) / fls(8 * eccsize);
+
 	return nbc;
 fail:
 	nand_bch_free(nbc);